Dyeing Of Blends

Submitted To- Submitted By-Mrs. Mehakdeep Duggal BSC F.D. 2Dyeing Of Blends

IntroductionBlending:

Blending is the combining of different fibres together intimately to achieve a desired product characteristic. Blends can influence colouring, strength, softness, absorbency, ease of washing, resistance to wrinkling, ease of spinning, cost, etc.Advantages of Blending: When two different types of fibres are blended, the properties of these two different fibres are synergised. For instance, in the blend of cotton and polyester, cotton provides the absorbency and polyester provides the strength.Blending is done to produce a fabric, which is economical by combining the aesthetic comfort properties of the natural fibres with the easy care and strength properties of synthetic fibers.Blending also helps to provide the fabrics light weight with all desirable characteristics.Improving spinning, weaving and finishing efficiency and the uniformity of product.

There are different types of dyes for dyeing textile goods. These dyes have different nature in fiber. It depends on fiber characteristics. Application of dyes in different fibers are given below:

Name of DyesApplicationAcid dyeMan made fiber(Nylon),Natural fiber (Silk, Wool)Direct DyeMan made fiber (Viscose),Natural fiber(Cotton)Vat dyeMan made fiber (Viscose),Natural fiber (Cotton, Silk, Wool)Disperse dyeNylon, Polyester, Acrylic, Tri-acetate, Di-acetateBasic dyeJute,AcrylicReactive dyeCotton, Wool, Silk, Viscose, NylonSulfur dyeCotton, ViscoseMordant dyeCotton, Wool, SilkPigmentCotton, Man made fiberMineralCotton, Wool, SilkAzoic dyeCotton, ViscoseAniline BlackCottonRapid and Rapidson dyeCottonOnium dyeCotton, JuteFibers are mixed together to generate a fabric with improved properties or to blend a less expensive fiber with a more expensive one to obtain a compromise between price and performance.When more than two or more different fibers are mixed intimately in a yarn and that yarn is used to make a fabric, the resulting mixture is referred to as a blend.Blends of polyester and cotton fibres have become very important to the textile industry.

When fabrics are made from mixtures of fibers, four different types of dyeing effects may be achieved :- Solid dyeing - both fibers are dyed the same hue and to the same depth. Reservation - one fiber remains undyed.3. Tone-on-tone - one fiber is dyed a deeper shade than the other.4. Cross dyeing - each fiber is dyed a different and contrasting hue.

Cotton gives the aesthetic and comfort properties demanded by consumers, while the polyester component adds to performance properties. Each fiber may be dyed the same colour, or they may be dyed different hues. Polyester has no affinity for most of the classes of dyes used to colour cotton, the cellulose being only stained by disperse dyes.

A. TO FACILITATE PROCESSINGB. TO IMPROVE PROPERTIES1. ABRASIVE RESISTANCE2. STRENGTH3. ABSQRBENCY - COMFORT4. ADD BULK AND WARMTH5. HAND6. DIMENSIONAL STABILITY7. RESISTANCE TO WRINKLING8. PERMANENT PLEATS OR CREASESC . TO PRODUCE MULT I -COLORED FABR I CSD. TO REDUCE COST I TO INCREASE COST SOME REASONS FOR BLENDING OF FIBERS

TYPES OF BLENDSFIBER BLENDSDIFFERENT FIBER TYPES BLENDED INTO A SINGLE YARNCOMBINATION FIBER BLENDS A. YARNS OF DIFFERENT FIBER TYPES WOVEN, KNITTED, OR BONDED INTO FABRIC B. SINGLE YARNS COMPOSED OFBLENDED FIBERS PLIED TOGETHER OPENING - CARDING - DRAWING COMBING SLIVER RING SPINNING PLYING YARNS CORE-SPUN YARNS FIBER MATS (NON-WOVENS) Filament Yarns vs. Staple YarnsWAYS TO BLEND FIBERS:CROSS-DYEINGYARN DYED FABRICSUNION DYEING A. DIFFERENT FIBER TYPES B. DIFFERENT BRAND NAME FIBERSRESERVE DYEING A. ONE BATH DYEINGS B. MULTIPLE BATH DYEINGSTONE ON TONE DYEINGMULTI-LEVEL DYEINGSTAINING DYEING OF BLENDSDYE SELECTIVITYDYEBATH CONDITIONS A. DYE AUXILLARIES B. DYEBATH TEMPERATURE C. STRESS ON FABRICDYESTUFF BLOCKAGE A. RETARDING AGENTS B. DYE'- MOLECULE BLOCKAGEDETERMINATION OF DYEING ON VARIOUS FIBERS % A. LEACH OUTS B. RIDERS IMPORTANT FACTORS IN DYEING BLENDSIMPORTANT CONSIDERATIONS IN DYEING BLENDSPREPARATION -EFFECT EACH OPERATION COULD HAVE ON THEDIFFERENT FIBERS IN THE BLEND.A. SINGEING - NATURAL FIBERS vs, SYNTHETICSB. DESIZING - SIZES NORMALLY USED CAN'DIFFERC. SCOURING - EFFECTS OF DETERGENT AND ALKALID. BLEACHING - CHOICE OF BLEACH ADVERSE EFFECTS OF BLEACHINGE. MERCERIZATION CAUSTIZATION EFFECTS OF SODIUM HYDROXIDEF. HEAT SETTING - EFFECTS OF HIGH TEMPERATURE DRY OR WET HEAT Classification of the methods for dyeing of P/C blendExhaust dyeing method or batch dyeing method- This is again classified in the following three groups- a. Two bath dyeing b. One bath one step dyeing c. One bath two step dyeing method Thermosol Dyeing method - It is again classified in to two groups- a. Continuous dyeing- b. Pad batch process (semi-continuous)

DYEING OF POLYESTER BLENDSLimited manufacture in IndiaMost popular blend :55/45 PET/WoolOther blend ratios : 70/30 , 20/80 55:45 blend warp and weft blended yarnPolyester Rich Blend: 70/30 (textured 100% PET warp & 55:45 blended weft)Wool Rich Blend : 20/80 (with 55:45 blended weft and 100% wool weft)

PRETREATMENT:Typical process sequence:Grey inspectionScouring

DryDye Singeing 11)Decatising and PressingStain removalWool presetting(crabbing)Heat setBrushing, CroppingSteam or DampDyeing methodsOne bath method : * simultaneous dyeing of PET and wool with disperse and wool dyes * common method for pale and medium depths of shade* economical, * minimum tendering of wool Two bath method: * mainly for navy and black shades * no particular advantage over one-bath method Dyeing of a Cotton/polyester Blend with Reactive and DisperseDyes:-The Thermosol process for dyeing polyester was developed by the DuPont companyfor the continuous dyeing of polyester fabrics. This single development allowed the rapidgrowth of polyester fabrics in the early to mid-fifties. The process involves padding onthe disperse dye together with auxiliaries that minimize migration, drying, then fixing thedye in the polyester by dry heating to a high temperatures about 190 205C. Duringthis process the fibre molecular chains open up at these elevated temperatures and thedispersed dyes vaporize and diffuse into the polymer. On cooling, the dyes are trappedwithin the fibre yielding coloured fibres that have good fastness properties.Proper preparation of the fabric is important in a continuous dyeing operation. Forcotton/polyester, the fabric must be absolutely clean, since residual oils or dirt will be setinto the fabric during the Thermosol treatment. The fabric must also wet outinstantaneously and uniformly to insure adequate absorption during the paddingoperation.Dyes for PET and WoolDisperse dyes (DD):

High temperature not suitableLow energy DDs-low sublimation fastnessMedium energy dyes pale shades or dyeing at 1060CHigh energy dyes- not suitable but can be used for max. colour yield and fastness is required applied to 1300C prior to PET/wool blending pH : 4.5 5.5.

Wool Dyes:Acid and premetallised dyes most suitableNo staining on PETBuild up ~40 - 500CComplete exhaustion at boil in 30 min.Dye selection is not criticalWet fastness is important : 1:2 metal complex preferredDyeing pH: 4.5 5.5Mixture dyes:

Disperse/wool dye mixture- available since 1985, suitable for 55:45 PET/woolAdvantages: *simplified selection, reduced weighing/handling of dyes * good reproducibility (from batch to batch or lab.to bulk scale) * tone and tone dyeings as a result of good compatibility of acid and disperse dyes within each mixture *suitable for computer colour matching

Single dye class: e.g. reactive disperse dyesDeveloped dyes show poor light fastness, not commercially suitable

Minimisation of damage to woolThe advantages of high temperature dyeing above 1100C areFast deep shadesShorter leveling timeBetter levellingLess staining of woolDisadvantages Wool degradation reduction in strength, elongation, abrasion resistance, yellowing Therefore, to protect the wool component during high temperature dyeing,Most common agent HCHO (5% owf) allows dyeing at1050C for 4 hrs1100C for 3 hrs1150C for2 hrs1200C for 1 hrpH: 3.5-4.5

Dyeing procedureSet bath with auxuliariesPreheat 10 20 min at 50 -700CAdd disperse and dissolved acid dyeTreat for 10 minRaise temperature to boil or 103-1060C 30-45 minDye for 1-2hrs depending on depth of shadeCool, cold and hot rinse shading 80 -1000COne-bath dyeing Improve dye exhaustionMinimise wool stainingWool protecting agent is necessaryRecipe:X% disperse dyeY% acid / metal complex dye3-5% HCHO (30%)1-2% dispersing agent , pH : 5 -6 with HAC Pretreat with auxiliary at 50-600CAdd disperse and acid dyesTreat for 10 minRaise temperature to 1100C/1200C in 45 minDye for 30 60 minAfter treatmentStaining of wool with disperse dyes cannot be avoided even if the process is carried out with most siutable dyes under the most favourable conditionsDisperse staining on wool poor fastness must be removed completelyOne-bath method reduction clear is not possibleAfter wash: 1-2 gpl non-ionic detergent, pH 5-6 with HAC, 20-30 min at 600C, good rinseWith deep shades, repeat the above process Two bath processUsed for deep shades -particularly navy and blackDye polyester component with X % disperse dyeY% carrier1 2% dispersing agentpH 5-6 with HACMaximum temperature :103 -1060C or boilCold rinseReduction clearing:3 gpl hydrose0.5- 1 ml/l ammonia(25%)0.5-1 gpl non-ionic emulsifying agentFor 30 min at 45 -500CGood rinse, acidify with HACDyeing of wool componentThermosol dyeingNot commonCan be used for coloration of PET component onlyWool component is dyed seperately (detail sin page 256-257)Dry heat treatment:190 -2000C for 45 60 secsNot harmful to wool except slight yellowingLess wool stainingCorrection of faulty dyeingsFaulty shades can be levelled or partially stripped with X gpl carrier2-4% levelling agent for wool1 2% emulsifying agentpH 5-6% with HACTreatment at boil for 1 2 hrs or 103 -1060C for 1 1 hrsIf only shade on wool is to be corrected, carrier is not necessaryConclusionsOne bath dyeing of Polyester/cotton blend fabrics with reactive disperse dyes in successful with SC-CO2 .The optimum dyeing temperature and pressure are about 393 K and 20 Mpa respectively . The dyeing behavior of Polyester/cotton blends is strongly affected by the dyeing characteristics of the cotton side.The colour fastness of dyed fabric is almost satisfactory ,but colour fastness become weak with a decrease in the dyeing temperature. In addition ,the colour fastness of fabric dyed in SC-CO2 is better than that with that the thermosol dyeing.

Treatment with chitin pretreatment give the good dry rubbing and washing fastness . The alkaline pretreatment affects the greater adhesion of chitin to the surface of polyester fibres, which is manifested by the greater colour strength .Pretreatment in an alkaline solution containing 10 g/l NAOH is permitted .The greater amount of chitin used ,the worse affects are observed .

The same effect is observed in case of azeeotropic mixture on the dyeing behaviour of 80/20 cotton blends .As the pretreatment time increased dye uptake was found increase . The slight improvement in fastness properties was also found

Dyeing of PET/COTTON blend with disperse dye containing the fluorosulfonyl group under high temp. dyeing conditions are feasible .Its decrease our labour cost, chemicals, energy.