Applications of nonwoven in Medical Textile

Introduction The term medical textile literally means textile used for medical purposes Textile apart from being a vital part human life is long since been used in medical field though the term has been coined very recently Textile materials have wide range properties such as flexibility elasticity strength etc Textiles used for medical purposes should be non-allergic noncarcenogenic non-toxic and antistatic in nature optimum fatigue endurance biocompatibility flame proof dyes must be non-irritant An important and growing part of the textile industry is the medical and related health care and hygiene sectors The extent of the growth is due to the constant improvements and innovations in both textile technology and medical procedures They are used in a number of separate and specialized applications which can be categorized as follows

In the present scenario Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Nonwovens are developed to impart special properties to product In order to be competitive today nonwovens producers must show high productivity at low cost At the same time the market demands higher quality In the medical and sanitary domain the use of appropriate fibers is an important condition for obtaining the required properties The Medical Textiles includes vast range of applications viz adhesive tapes bandages beddings blankets castings diapers dressings eye pads gauzes protective clothings sutures surgical covers surgical clothings swabs supports sanitary products hospital gowns

etc It also finds application in extra-corporeal devices like artificial kidney liver heart amp mechanical lung ligaments vascular grafts heart valves blood vessels artificial skins etc Range of natural fibers and biodegradable polymers with non-biodegradable synthetic polymers is being utilized for developing new products in medical textiles Since the medical textile applications are directly related to the life of human being those are required to undergo stringent testing and hygienic criteria which led to innovative use of variety of fibers and lot of developments took place in this areaThe article will discuss the development in Medical Textiles field which will continue to help to improve the life of human being considerably with the aid of non-woven textiles

Medical Textiles

Based on applications the medical textile can be broadly categorized as follows

Personal health carehygienic products Bedding clothing surgical gowns Cloths wipes surgical curves surgical hosiery diapers etc

Non-implantable material or medical dressings amp auxiliaries wound dressing bandage plasters gauge lint wadding etc

Implantable materials sutures vascular grafts artificial ligaments and artificial joints

Extra corporal devices Artificial kidneys liver amp lungs etc

The nonwovens are used for the given applications in different forms Wound care was and still is the primary use for medical and surgical nonwovens Nonwovens find applications in a variety of products viz absorbent pads incontinence products apparel for patients and staff Baby diapers bed linen and blankets burn dressings gowns disposable underwear dressings drug delivery devices face masks filter media nasal strips pillows shoe covers sponges sutures tissue scaffolds towels wraps etc

Categories of medical textilesBased on applications the medical textile can be broadly categorised as follows

Personal health carehygienic products Bedding clothing surgical gowns cloths wipes surgical curves surgical hosiery diapers etc

Non-implantable material or medical dressings amp auxiliaries Wound dressing bandage plasters gauge lint wadding etc

Implantable materials Sutures vascular grafts artificial ligaments and artificial joints

Extra corporal devices Artificial kidneys liver amp lungs etc The nonwovens are used for the given applications in different forms

Implantable Medical TextilesThe materials are used in effecting repair to the body whether it is wound closure (sutures) or replacements Surgery like vascular grafts artificial ligaments etc) There are of many shapes and sizes for duplications as found in human body Filament texturised yarns used nowadays which are coated to prevent leakage of blood while tissue is forming on the inner walls

1048766 Carbon fiber is a popular material for tissue repair

1048766 Suspensory and reinforcing surgical meshes are used in plastic surgery for repairing defects of the abdominal wall Surgical treatments of hernia in Urology etchellip

1048766 Hydrophobic sanavel felt dressings are high porosity textiles made from man- made fibers designed for treatment of bums and different dermatological defects

Generally the following boding processes are used for nonwovens made of pulp fibres thermal bonding binder bonding combined bonding spunlace bonding

Non ndash implantable materialsThese materials are used for external applications on the body and may or may contact with skin They are made form co-polymer of two amino acids They are employed as covering absorbent protective and supports for injured or diseased part They are different types

Primary wound dressingsPlaced next to the wound surface Nonwoven with a binder content of 60 and made from cellulose fabrics are being used

AbsorbentSimilar to wound pads used in surgery Manufactured from well-bleached carded and cleaned cotton fabrics

BandagesThese are narrow cotton or linen plain weave cloth of low texture either woven or knittedEx Plaster of Paris Bandage orthopaedic bandage crepe Bandage

Protective eye paidScientifically shaped 2 frac34rdquo x2 frac34 x to lit over the eye used in outpatient clinic and industrial medical department

Adhesive tapesIt is narrow plain weave fabric having a coating of adhesive paste It is used with other pads to conform them to the injury

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

etc It also finds application in extra-corporeal devices like artificial kidney liver heart amp mechanical lung ligaments vascular grafts heart valves blood vessels artificial skins etc Range of natural fibers and biodegradable polymers with non-biodegradable synthetic polymers is being utilized for developing new products in medical textiles Since the medical textile applications are directly related to the life of human being those are required to undergo stringent testing and hygienic criteria which led to innovative use of variety of fibers and lot of developments took place in this areaThe article will discuss the development in Medical Textiles field which will continue to help to improve the life of human being considerably with the aid of non-woven textiles

Medical Textiles

Based on applications the medical textile can be broadly categorized as follows

Personal health carehygienic products Bedding clothing surgical gowns Cloths wipes surgical curves surgical hosiery diapers etc

Non-implantable material or medical dressings amp auxiliaries wound dressing bandage plasters gauge lint wadding etc

Implantable materials sutures vascular grafts artificial ligaments and artificial joints

Extra corporal devices Artificial kidneys liver amp lungs etc

The nonwovens are used for the given applications in different forms Wound care was and still is the primary use for medical and surgical nonwovens Nonwovens find applications in a variety of products viz absorbent pads incontinence products apparel for patients and staff Baby diapers bed linen and blankets burn dressings gowns disposable underwear dressings drug delivery devices face masks filter media nasal strips pillows shoe covers sponges sutures tissue scaffolds towels wraps etc

Categories of medical textilesBased on applications the medical textile can be broadly categorised as follows

Personal health carehygienic products Bedding clothing surgical gowns cloths wipes surgical curves surgical hosiery diapers etc

Non-implantable material or medical dressings amp auxiliaries Wound dressing bandage plasters gauge lint wadding etc

Implantable materials Sutures vascular grafts artificial ligaments and artificial joints

Extra corporal devices Artificial kidneys liver amp lungs etc The nonwovens are used for the given applications in different forms

Implantable Medical TextilesThe materials are used in effecting repair to the body whether it is wound closure (sutures) or replacements Surgery like vascular grafts artificial ligaments etc) There are of many shapes and sizes for duplications as found in human body Filament texturised yarns used nowadays which are coated to prevent leakage of blood while tissue is forming on the inner walls

1048766 Carbon fiber is a popular material for tissue repair

1048766 Suspensory and reinforcing surgical meshes are used in plastic surgery for repairing defects of the abdominal wall Surgical treatments of hernia in Urology etchellip

1048766 Hydrophobic sanavel felt dressings are high porosity textiles made from man- made fibers designed for treatment of bums and different dermatological defects

Generally the following boding processes are used for nonwovens made of pulp fibres thermal bonding binder bonding combined bonding spunlace bonding

Non ndash implantable materialsThese materials are used for external applications on the body and may or may contact with skin They are made form co-polymer of two amino acids They are employed as covering absorbent protective and supports for injured or diseased part They are different types

Primary wound dressingsPlaced next to the wound surface Nonwoven with a binder content of 60 and made from cellulose fabrics are being used

AbsorbentSimilar to wound pads used in surgery Manufactured from well-bleached carded and cleaned cotton fabrics

BandagesThese are narrow cotton or linen plain weave cloth of low texture either woven or knittedEx Plaster of Paris Bandage orthopaedic bandage crepe Bandage

Protective eye paidScientifically shaped 2 frac34rdquo x2 frac34 x to lit over the eye used in outpatient clinic and industrial medical department

Adhesive tapesIt is narrow plain weave fabric having a coating of adhesive paste It is used with other pads to conform them to the injury

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Implantable Medical TextilesThe materials are used in effecting repair to the body whether it is wound closure (sutures) or replacements Surgery like vascular grafts artificial ligaments etc) There are of many shapes and sizes for duplications as found in human body Filament texturised yarns used nowadays which are coated to prevent leakage of blood while tissue is forming on the inner walls

1048766 Carbon fiber is a popular material for tissue repair

1048766 Suspensory and reinforcing surgical meshes are used in plastic surgery for repairing defects of the abdominal wall Surgical treatments of hernia in Urology etchellip

1048766 Hydrophobic sanavel felt dressings are high porosity textiles made from man- made fibers designed for treatment of bums and different dermatological defects

Generally the following boding processes are used for nonwovens made of pulp fibres thermal bonding binder bonding combined bonding spunlace bonding

Non ndash implantable materialsThese materials are used for external applications on the body and may or may contact with skin They are made form co-polymer of two amino acids They are employed as covering absorbent protective and supports for injured or diseased part They are different types

Primary wound dressingsPlaced next to the wound surface Nonwoven with a binder content of 60 and made from cellulose fabrics are being used

AbsorbentSimilar to wound pads used in surgery Manufactured from well-bleached carded and cleaned cotton fabrics

BandagesThese are narrow cotton or linen plain weave cloth of low texture either woven or knittedEx Plaster of Paris Bandage orthopaedic bandage crepe Bandage

Protective eye paidScientifically shaped 2 frac34rdquo x2 frac34 x to lit over the eye used in outpatient clinic and industrial medical department

Adhesive tapesIt is narrow plain weave fabric having a coating of adhesive paste It is used with other pads to conform them to the injury

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Non ndash implantable materialsThese materials are used for external applications on the body and may or may contact with skin They are made form co-polymer of two amino acids They are employed as covering absorbent protective and supports for injured or diseased part They are different types

Primary wound dressingsPlaced next to the wound surface Nonwoven with a binder content of 60 and made from cellulose fabrics are being used

AbsorbentSimilar to wound pads used in surgery Manufactured from well-bleached carded and cleaned cotton fabrics

BandagesThese are narrow cotton or linen plain weave cloth of low texture either woven or knittedEx Plaster of Paris Bandage orthopaedic bandage crepe Bandage

Protective eye paidScientifically shaped 2 frac34rdquo x2 frac34 x to lit over the eye used in outpatient clinic and industrial medical department

Adhesive tapesIt is narrow plain weave fabric having a coating of adhesive paste It is used with other pads to conform them to the injury

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

BandagesThese are narrow cotton or linen plain weave cloth of low texture either woven or knittedEx Plaster of Paris Bandage orthopaedic bandage crepe Bandage

Protective eye paidScientifically shaped 2 frac34rdquo x2 frac34 x to lit over the eye used in outpatient clinic and industrial medical department

Adhesive tapesIt is narrow plain weave fabric having a coating of adhesive paste It is used with other pads to conform them to the injury

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Extra corporeal devicesExtra corporal devices are mechanical organs that are used for blood purification and include the artificial kidney the artificial liver and the mechanical lung

Artificial kidney1048766 Tiny instrument about the size of a two ndash cell flashlight1048766 Made with hollow hair sized cellulose fibres or hollow polyester fibre slightly latest than capillary vessels1048766 Fabric which is used to remove waste products from patientrsquos blood

Artificial liverMade with hollow viscose to separate and dispose patients plasma and supply fresh plasma

Artificial heart1048766 An 8 ndash ounce plastic pump lined with dacom velour to reduce damage to blood and is a chambered apparatus about the size of a human heart1048766 Silastic backing makes the fabric imperious to emerging gas that is not desirable in the blood

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Mechanical lung1048766 Made with hollow polypropylene fibre or a hollow silicone membrane1048766 Used to remove carbon-di-oxide from patientrsquos blood and supply fresh oxygen

Health care textilesAn important area of the textiles is the health care and hygiene sector among other medical applications The range of products available for health care and hygiene is vast but they are typically used either in the operation theatre or in the hospital wards for hygiene care and safety of the staff and patients

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Application of non woven in medical The properties of non-woven fabrics are determined by those of the constituent polymer or fiber and by the bonding process For instance expanded PTFE products can be formed to meet varying porosity requirements Because of the expanded nature of their microstructure these materials compress easily and then expand-a suture for example can expand to fill the needle hole made in a tissue-allowing for tissue in growth in applications such as arterial and patch grafts Polyurethane-based nonwovens produce a product that resembles collagen us material in both structure and mechanical properties particularly compliance (extension per unit pressure or stress) The porosity of both PTFE- and polyurethane-derived nonwovens can be effectively manipulated through control of the manufacturing processes Hence by controlling the various parameter of non-woven they can utilize effectively in different applications of medical

Reasons due to which Nonwovens became famous in medical field

Nonwoven possesses following properties due to which they became famous in medical field

Better performance wrt comfort thickness and weight water vapor transmission and air permeability

Increased protection for user better physical properties like tensile tear resistance abrasion resistance etc Various parameters can be controlled easily like Porosity Weight of fabric

and Thickness Nonwovens are easy to sterilize Various manufacturing technique options according to applications Economical manufacturing process etc Excellent barrier properties Superior efficiency Less potential for cross contamination

Fibers used in manufacturing of Nonwovens for medical applications

Cotton Polyester Polypropylene Viscose Glass Fiber Wood fluff amp Polyamide Chitin Layocell

Developments in medical nonwoven

Advanced cellulosic nonwovens Previously regenerated cellulosic fibers enjoyed half century of rapid expansion Since then synthetics have grown to dominate the market Cotton for centuries the most important of all fibers is taking second place to the combined weight of synthetics and viscose rayon Rayon now appears relegated to little more than a niche in a global fiber market driven by the ready availability of cheap fossil fuels and the demand for commodity textiles and nonwovens Nonwoven production

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

was founded on the ready availability of low-cost viscose rayon fibers and these continued to dominate the industry until the mid seventies Since then the reducing cost of synthetics coupled with their easy conversion into binder-free spun-laid and melt-blown fabrics caused a steady decline in rayons nonwoven market share

Previously when disposable diapers came in two pieces (reusable plastic pant with rectangular absorbent pad) latex bonded rayon was the cover of choice At this time flush ability was becoming a key development issue The rectangular inserts with their heat-sealed latex-bonded rayon covers were too stable to be disposed of in the toilet even after tearing in half New wet-laid nonwovens made from the specially developed self-bonding collapsed-tube rayon fibers had no wet-strength at all and dispersed easily in flowing water However when treated with the standard wet-strength agents used in the paper industry it became strong enough in use and remained disintegratable in toilet turbulence The introduction of the more convenient one-piece diaper pushed mothers concerns about flush ability into the background Latex-bonded 100 rayon continued as the leading cover on one-piece diapers but in 1974 coverstocks containing 50 polyester were market-tested for the first time Consumers found they could not really spot the difference from the 100 rayon fibre versions so in a second test the latex bonded rayonpolyester blend was put through a point embossing calendar to give it a textured surface This time the mothers could express a preference for the patterned over the plain and a unique new product was born This first use of synthetic fibre in what had been regarded as an absorbent fibre fortress appeared to be driven by nothing more than the concern over the escalating price of rayon

Lyocell nonwovens Lyocell makes excellent nonwovens especially in those processes that allow its superior aesthetics shine through like needle punching and HE Its high strength is of little intrinsic value in disposables but enables the nonwoven producer to reduce basis weight while meeting targets Its freedom from shrinkage and high wet stability allows higher area yields in HE processes and its high modulus prevents it from collapsing in the wet to the same extent as viscose rayon Fibrillation the development of surface micro fiber on wet abrasion or in high-pressure entanglement adds an additional dimension for the nonwoven development Unfortunately while it has established itself in several profitable niches its premium positioning has so far prevented its use in mainstream disposables

Spun-laid lyocell Most fiber-forming polymer solutions can also be converted into continuous yarns film sponges or indeed nonwoven fabrics Lyocell dope is no exception and many of the characteristics of the lyocell process make it a better basis for spun-laid nonwovens than the viscose process ever was Technically speaking the challenges is not great In nonwoven industry the leading product are nearly always with those the lowest cost and justification of spun laid cellulosic on added value alone has failed several times already The ultimate in economy is arises from inherently low cost raw material converted on state of the art machinery at the largest possible

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

scale The nonwoven industry enjoys the economies of (say) polypropylene because PP is a byproduct of the worlds largest industry energy Viscose rayon a premium product of the timber industry requires the most costly grades of wood pulp Lyocell is currently similar but its simple production process has the so far unexplored potential to use cheaper pulps It also have potential to achieve very high level of scale in textile and hence the economies of scale that may ultimately interest the major nonwoven converters

New development in biodegradable nonwovensOver the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger In fact in the largest and most potentially environmentally-sensitive market cover stock for disposal diapers and biodegradable products are non-existent An expressed consumer preference for ldquoenvironmentally friendlyrdquo products in the disposables area at least appears to meet an unmet need

How the nonwovens are manufactured

Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the medical applications point of view are asfollows

Needle punched nonwoven blanketsTraditionally woven blankets where used in the Far East and Middle East countries These methods are not economical and for that purpose a special technique has been developed known as needle punching This process consists of three main stages

Predatory process Web formation Needling the fibres web

The various particulars areas as follows

Variables ParticularsFabric weight (gsq metre) 350

Needling density (psq metre) 250Depth of penetration (mm) 9

It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling densityAir permeability value reduces as there is increase in the nonwoven bulk density

Application development foam substitutionThe objective for research is to develop a suitable nonwoven for the medical applications

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Web forming process developmentForming a random nonwoven webs with the static methodThis development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer or the panel with the circular holes is electrified with 20kv and placed over conveyor belts

This process becomes very usefuli) To maintain the uniformity of webii) Iin manufacturing hybrid and composite products which are used for implantation purpose effectively

Wet-laid nonwovensi) Borrowedrdquo technology from the paper industryii)Fibres 03 mm ndash 25 mm amp 60 dtex maxiii)Fibres are dispersed and suspended in water at 005 concentration

Cross-lapped nonwovensCross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight Here the delivery belt is doubled ie batt of several layers are being formed the card web enters the lappers with constant speed the layering carriage has to perform an oscillating movement as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area

Needle loom for nonwovenIn recent years development has taken place for manufacturing all types of needle loom of nonwoven having thefollowing advantages-I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machineII) Superior web properties can be obtained with fewer needle preparationIII)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications

Manufacturing processes for medical nonwovens

Web Formation The most popular techniques for medical nonwovens are spunbonding meltblowing and their composites (SMS) in specific end uses Spunbonding is used when more strong webs are needed Spunbonded webs are strong in both machine direction (MD) and cross direction (CD) They are soft porous

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

and dimensionally stable Spunbonding is mostly used for products like face masks head wears shoe covers bed linens and disposable clothing etc Dry laying wet laying and carding are used for different web properties depending on web thickness required speed of bonding technique to be used etc Carding is adapted for lightweight web production for technical and hygienic products Carding produces very high quality webs at very high speedsBonding is carried out by many methods including thermal bonding for synthetic fibers and their blends Hydroentangling as the fastest growing bonding technique is used explicitly in medical nonwovens for that textile-like hand and feel thats desirable in products like gauzes dressings hospital apparel etcNeedlepunching finds application in bonding various fibers or webs of medium thickness Needlepunching is fast effective and often chosen technique for varied applications It is also cost effective Apart from all these techniques stitchbonding is also used Chemical bonding is often used for making elastic nonwovensPost process for medical nonwovens is to give the product a suitable finish for its specific end use The different types of finishes used in medical nonwovens are

Soil Release Agents for bed linens gowns and apparel which are designed for multiple usages May also be used on curtains blankets etc

Softeners to make the webs feel soft against the skin May be used for disposable undergarments pillows bed sheets etc

Water repellents used for bed sheets for kids barrier apparel etc Flame Retardant Finishes used for bed linens curtains apparel lab coats etc Antibacterial Finish very commonly applied to gauzes dressings and sutures

The most popular one is silver nanocrystal finish Resin and Hand Builders used for apparel gowns bed linens etc

Nonwovens in disposable applications Disposable literally means designed for or capable of being thrown away after being used or used up Disposable textiles are textiles used in or as apparel for functional applications designed to be disposed off after use They are bound by ldquouse and throwrdquo concept Disposable nonwovens are those nonwovens for short life applications in single use including hygiene medical consumer wipes industrial wipes and others Hygiene nonwovens include baby diapers training pants adult diapers (adult incontinence) and feminine care products (external and internal) The external feminine care products include sanitary napkins and pads The internal feminine care products refer to tampons Medical nonwovens include drapes and gowns sterile wrap swabs and dressings Among them surgical gowns drapes and drape pack parts account for almost two third Following are the advantages of nonwovens in medical textiles

Excellent barrier

Low linting

Tear resistant

Single use

Always available

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

No repair

Decreased storage space

No hidden costs

Cost effective to use

Some application of nonwovens in medical textiles

Products used for medical surgical dressings

Wound care productsA wound dressing is used for many purposes including protection against infection absorption and exudation of blood and excess fluids healing and application of medication ideally a wound dressing should be soft pliable pad the wound to protect it from further injury be easily applied and removed be sterile lint free and non ndash toxic The wound dressing should not adhere to the wound allowing easy removal without disturbing new tissue growth An absorbent cotton swab placed at the wound and tied with gauze forms the oldest form of wound dressing However this traditional method of wound covering is found to stick to the wound and does not provide a moist microclimate to the wound conducive to its faster healing

The modern wound dressing is usually made of three layers-(a) Wound contact layer - It should not stick to the wound or cause maceration of the skin if the dressing is not changed It can be woven knitted or non-woven made from silk viscose polyamide or polyethylene(b) Middle absorbing layer - If has to absorb blood or liquids while providing a cushioning effect to protect the wound It is generally a non-woven composed of cotton or viscose(c) Base Material It provides a means by which the dressing is applied to the wound The material is coated with acrylic adhesive to hold the dressing in place eliminates the need for bandage

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Because sterilization is a major concern for surgical dressings nonwovens are considered Nonwovens can be smooth and lint-free for the most part This allows lesser chance for debris to be left at the wound Nonwoven can be made softer and more absorbent by latex or thermal calendaringFor postndashoperative dressing sophisticated nonwoven structures such as perforated films on absorbent base polymersnonwoven welded laminate and metalised nonwoven are used Polypropylene is promoted as most unwettable fibre but it can also be quite wettable if converted to a fibrous web by melt blowing In melt blowing a stream of molten polymer is subjected to blasts of air which form tiny fibrils that fall randomly as a web This gives polypropylene a role of absorbable dressingrsquos material Traditionally polypropylene is used in wound dressings in fibre or fabric form coupled with absorbent materialPolysaccharide based dressings have increasingly become viable alternative to biologically incompatible and often problematic cotton and viscose gauzes used for wound dressings Abundantly available alginates and their relatively ease of solubility in particular have been instrumental in developing these fibres and their applications as vehicles for drug delivering The other polysaccharide is Branan ferulate that is gel spun It is extracted from corn bran and has water soluble properties This polysaccharide can infiltrate the biological activities in the body and hence accelerate wound healing

BandagesBandages are designed to perform a whole variety of specific functions depending upon the final medical requirement They can be woven knitted non ndash woven or composite in structure They can be classified into various classes depending upon the function they serve as(a) Simple bandages ndash These are fixation bandages that can be elastic or inelastic in nature Adhesive bandage cohesive bandages and tubular bandages belong to this class A simple non ndash elastic bandage is required to the dressing in proper place over the wound One such bandage is simple open weave cotton or viscose fabric cut into strips which have been scoured bleached and sterilized The problems of fraying in the plain woven bandage are overcome by use of non-fraying cotton leno bandage The structure of bandage is more stable with crossing warp threads in the leno woven structures These can be further coated with paraffin to prevent sticking of the bandage to the wound Further some ointment dressing can also be given along with paraffin to aid faster healing of the wound Elasticated yarns are incorporated into bandages to form elastic bandage for providing support and comfort(b) Light support bandages ndash Woven light support bandages are used for sprains or strains Elastic crepe bandages are used for sprained wrist or ankle support The elasticated properties of these bandages are obtained by weaving cotton crepe yarns that have twist content Similar properties can also be achieved by combination of two warp sets with normal and high tension Stretch and recovery properties of these bandages apply sufficient tension to support the sprained limb(c) Compression bandages ndash Compression bandages are used to exert a certain compression for the treatment and prevention of deep vein thrombosis leg ulceration and varicose veins Depending upon the compression they provide compression

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

bandages are classified as light moderate high and extra ndash high compression bandages They can be woven warp or weft knitted from cotton and elastomeric yarns(d) Orthopaedic bandages ndash These bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort Non ndash woven orthopaedic cushion bandages are made from polyester or polypropylene and blends of natural and synthetic fibres Polyurethane foam can also be used Light needle punching gives bulk and left to the structure for greater cushioning effectKnitting is commonly used for manufacture of bandages in tubular form with varying diametersThe weft knitting machine is chiefly used for production of two classes of medical textiles Viz support bandages and elastic bandages Tubigrip is an example of circular weft knitted cotton fabric with rubber yarn laid ndash in manufactured in tubular lengths of different diameters Since these garments are to be continuously worn the seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movement Similarity the warp knitting machines is used to manufacture mainly the wound dressings bandages and vascular grafts The tubular structures can best be produced on circular warp knitting machines However these are traditionally produced on double bar Rachel machines due to thelimitation of patterning on these machines With the new developments of electronically controlled flexibility in production of various tubular medical devices has been achievedFabric shaping can be controlled by modifying the structure of fabric within the garment or altering the stitch length In bandage applications control of elasticized yarn can be made using such electronically controlled pattern ring to alter the underlap or the stitch length being knitted Circular warp knitting machines can be used for making stockings that can be sued provide pressure gradients along the leg after surgery aiding blood circulation Electronic speed monitoring and variable speed drive to the let ndash off for the feed packages have helped to obtain consistent yarn quality Spacer knitted fabrics can be used as bandages in normal or composite form

Pressure garments for hypertrophic skinThis is a special class of bandages used for healing wounds caused by burns Pressuregarments are made by using a variety of elastic fabrics and can be simple tubes to fit individual limbs or full garments if the burn area is large These garments are useful for the care of burnt skin area for cuing of scars The generated pressure on the affected area should help alleviate the itching of the scars The average pressure to be applied to the treated tissue area is about 25 mm of Hg During this burns rehabilitation process the pressure garment has to be worn continuously may be for periods as long as 12 months There is a wide range of pressure garments due to the varying size of the patients and the different methods of fitting the garments by the therapists So it is best for the hospitals to buy the pressure fabrics and make garments to suit the patientrsquos needsTwo main types of fabrics are currently used for making pressure garments1048766 Firm elastic fabric containing elastane yarns is used for making pressure garments This fabric is usually warp knitted1048766 Tubigrip is a circular weft knitted cotton fabric with rubber yarn laid ndash in tubular lengths of different diameters Since these garments are to be continuously worn the

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

seams should be strong enough to resist strong transverse forces Also the seam should have high extensibility and recovery to allow for body movementIn the various suitable fabric structures and garment constructions the following have been establishedlsquoFabrics with low coefficient of friction are more comfortable than those with high coefficient of friction and are less likely to cause maceration Hence powernet sleeknit fabrics are found to be more suitable as compared to weft or warp knit fabrics However the deviation in the coefficient of friction was found to be quite high for almost all fabrics The face side of all fabrics was rougher than the reverse side Hence an optimum construction is to be arrived at for comfort and recovery of the patient

GauzeGauze and paraffin coated gauzes are the most commonly used dressing Most gauze is made up from cotton in the form of a loose plain weave The typical yarn density per inch is 12 ndash 19 for warp and 8 ndash15 for the weft 44sNe warp and 54sNe carded weft yarn is generally used Gauze is mostly used as a direct dressing for wounds or may be used in internal pads and general swabbing applicationsThe burns and skin grafts have their dressings changed frequently and the difficulty with this gauze is that its fibres stick to the wound The removal is not only painful but also destroys the regenerating tissues This leads to delay in healing process and also leaves scars behind The problems associated with the traditional woven cotton gauze are as below1048766 A possibility of loose fibres getting caught in the wound1048766 A large adherence surface1048766 Irritation or mechanical injuring of the wound when the dressing is changed1048766 Prolonged time of wound healingParaffin ndash coated gauze is usually multi ndash layered is a little easier to remove but it does not rapidly absorb the wound liquids Also this being a petroleum based coating can liquefy at body temperature and introduced foreign matter into the wound It is used to treat burns and scalds

PlasterPlasters are made up of three layers ndash 1) Plaster fabrics 2) adhesive and 3) ndash wound pad A simple plaster cast consists of gauze impregnated with plaster of Paris The modern plaster fabric is made from spun bonded nonwovens of cotton viscose polyester or glass fibre The adhesive used for plaster fabric is acrylic that doesnrsquot stick to the skin The cushioning wound pad is made from knitted viscose fabric impregnated with an antiseptic The highly absorbent wound pad helps in rapid absorption of secretion from the wound

Others dressingsThe other surgical dressings include wadding and lint Wad ndash ding is an absorbent material to prevent adhesion to wound or fibre loss it is covered with a non ndash woven fabric Lint is a plain weave cotton fabric that is frequently used in treatment of mild burns

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use

Conclusion

Medical textile market is totally saturated with nonwoven products today Nonwovens because of their easily modifiable properties and excellent performance have become indispensable in this field Products used for medical or surgery applications may at first sight seem either very simple or complex items In reality however in-depth research is required to engineer a textile for even a simplest cleaning wipe in order to meet stringent professional specifications Advances in nonwovens have resulted in a new breed of medical textiles Advanced composite materials containing combination of fibers and fabrics have been developed for applications where biocompatibility and strength are required It is predicted that the nonwoven materials will continue to have greater impact in this sector owing to the large member of characteristics and performance criteria required from these materials

References Antimicrobial and medical use textiles Textile Asia sept 2001 Nonwovens amp Technical Textiles section published in ITJ Sept 2008 The use of innovative textile structures for medical applications ATJ Nov 2001 Nonwovens as medical textiles by Priyadarshini Malshe published in f2f in Oct

2008 Handbook of Industrial Textiles by Sabit Adanur Textile in hospital hygiene IFB Jan 2004 G Fisher Technical Textiles Int July August 2003 19 Wound Treatment Medical textiles Jan 2003 Meeting demand for cost efficient production of hollow fiber membranes for

medical use