Textile Chemicals

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Looking at the overwhelming responseand the tremendous amount ofinterest evoked by our earlier article(International Dyer, January 2006),

we were encouraged to work further on thisconcept and to concentrate more and moreproducts for the textile-processing field (punintended). Also, a large number oftechnicians and purchasers, who found thatby using concentrated products for captiveconsumption, their costs could be reduced,have started hounding us to offer concen-trated products wherever possible. Someeven jokingly said that if we can offer saltand water in concentrated form, they areready to buy it.

Human need or greed is really insatiable!The faith of this tribe, as well as newbusiness opportunities, has forced us tosharpen our technical skills to add somemore concentrated products to our portfolio.

PretreatmentSarapol-AIO (Conc) is a unique all-in-onespeciality product for pretreatment of cottonyarn, knits, terry towels and fabrics, havingmultifaceted properties of wetting, peroxidestabilization, detergency; allowing combinedscouring and bleaching to take place indiscontinuous machines. This product isnow available in 70% strength, which notonly offers a cost advantage but also easeof operation with dosing equipments as wellas with unskilled workers.

Silicone-based defoamers have beenalways treated with a jaundiced view due tothe continuous fear of the emulsion splittingand creating silicone oil spots. Sarex hasdeveloped two very robust siliconedefoamers, which can take care of foamcontrol in all types of textile-processingoperations, such as sizing, scouring, dyeing,etc. Sarasil-D (Conc) is available as a 70%

concentrate emulsion (Fig.1). This product isapplicable in neutral to acidic pH on jet andoverflow machines for dyeing of polyester,wool, nylon and their blends.

In order to overcome the limitation of pH

suitability, Sarex has also developed a jet-stable, pH-stable, high-temperature-stablesilicone defoamer, Sarasil-JS (Conc) (Fig.2).This product is available in 40% strengthand can be diluted with the help ofXanthane gum as a viscosity modifier foreasy use as a stock solution to avoid lossesdue to overweighing or spillage. The 100%active is ready in the lab and awaiting bulktrials.

Formulators of textile auxiliaries foreverhave a challenge to incorporate defoamersin their detergents to provide foam-freedetergents used in high-turbulenceequipment (Fig3). Conventional foam-controlagents tend to be incompatible withsurfactant-rich systems, leading to turbidappearance and phase separation. OurSarasil-DET (Conc), on the other hand,allows formulation of highly concentrateddetergents to be uniform and clear inappearance and exhibit excellent storagestability. This allows a formulator to develop80-90% active detergent systems with 10-20% max. water content. Sarasil-DET (Conc)is available as a 100% active, jet-stable, pH-stable, surfactant-stable, high efficiencyanti-foaming agent.Organic Peroxide Stabilizer: Conventionallyavailable in 20-30% aqueous formulation,based on mixtures of sequestrants (ex-amino polycarboxylic acids), iron chelatingagents (ex-phosphonates), dispersants andperoxide activators (Fig4). We havedeveloped a 100% active product in a stablepowder form, ie. Sarastabil (Conc). Thisproduct can be readily diluted to make astock solution for use in textile processing.

DyeingLubricating Agents: Friction marks orcrease marks constantly plague processorsin all wet processing machines. The role oflubricant is to reduce the extent of frictionencountered by the fabric when processedin rope form in high-turbulence equipment.This mechanism leads to reduction inrunning creases in natural and manmadefabrics during the wet processing.

Three categories of lubricants areavailable: (a) self-dispersible oils or fats;(b) surfactant-based; and (c) polymers.Self Dispersible Oils or Fats: Sarex has developed two unique lubricants, viz. Saracrease-HG (Conc) and Saracrease-AS (Conc). Saracrease-HG (Conc): A sulphonatedtriglyceride available in an 80% active,slightly viscous, anionic, pourable paste. It

Concentratingon mmoorreeConcentratesBy Dr Naresh M. Saraf and Deepak V Alat,of Sarex Overseas, India

Fig 1: Defoaming action of Sarasil-D (Conc)

Fig 4: Mechanism of Peroxide Bleaching

Fig 3: Mechanism of defoaming

Fig 2: Action of alkaline stable defoamerSarasil-JS (Conc)

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Textile Chemicals

prevents the formation of running creasesduring pretreatment and dyeing and in theafter-soaping of knitted and woven goods inrope form (Fig.5). It is used for cellulosics,wool, polyamide, polyester and blends ofthese fibres.Saracrease-AS (Conc): A nonionic, self-dispersible, fatty acid ester, available in100% active, viscous liquid. It resists theformation of creases in natural and man-made fibres during wet processing of wovenand knitted fabrics in rope form. It can beapplied on high-turbulence equipment. Thisproduct, being nonionic, is suitable fordyeing of cationic dyeablepolyester/polyester, polyester/polyacry-lonitrile and polyacrylic, since it does notinteract with cationic dyes.

Both Saracrease-HG (Conc) andSaracrease-AS (Conc) can be used forcorrection to minimise creases formedearlier due to poor working conditions.Polymers: We have already described thesein our last article. Saracrease (Conc) is a100% product made up of polyacrylates.From 1 kg Saracrease (Conc), the end usercan make 50-60 kg of ready-to-use product,offering substantial saving of money andspace.Multifunctional Dye Bath Auxiliary: One ofthe main problems faced by a dyer is batch-to-batch variation and, in the case ofpackage dyeing, variation in the largepackages (> 1.2 kg) or MIMO differences.The variations are associated with poor

solubility of dyestuffs in the presence ofsalt, alkali and hardness, high strike rateand poor dye-bath stability.

Traditionally urea is used as a solublisingaid but it increases BOD value. Normalpolymeric dye-bath conditioners are notmuch help in controlling strike rate. Toovercome this problem, we have developedSarakol-RDL, which increases the solubilityof dyestuffs under adverse dyeingconditions, maintains dye-bath stabilitythroughout dyeing and prevents precipi-tation, particularly in package dyeing. It hasa sequestering action on calcium but doesnot have a demetalising action on metal-containing reactive dyes and reduces strikerate, leading to a level dyeing (Fig.6).Unfortunately the product has no

comparison!We have successfully been able

concentrate this product to 60%, calledSarakol-RDL (Conc), thus resulting in lot ofsaving of freight and packing cost. It wasinitially available as a 30% product.Buffered Alkali: Saradye-R was introducedas a liquid buffered alkali for exhaust dyeingof cotton with reactive dyes, as it maintainsthe required pH during the fixation phase,thereby improving consistency andreproducibility of shade. The quantity ofSaradye-R required for fixation is much lessthan conventional alkali and therebyreduces TDS in the effluent stream (Fig7).Also it negates the ill influences ofhardness-causing substances in thedyebath.

Fig.5: Crease prevention by lubricants likeSaracrease HG (Conc)

Fig. 6: Effect of Sarakol-RDL (Conc) on thesolubility of reactive dyes Recipe I

Yellow CA 0.375%Red CA 0.018%Blue CA 0.138%

Recipe IIYellow CA 0.22%Red CA 0.16%Blue CA 0.01%

Recipe IIIYellow CA 0.06%Red CA 0.90%Blue CA 2.4%

Recipe IVYellow CA 2.6%Red CA 1.7%Blue CA 1.5%

With Sumifix SupraRecipe ISFS Yellow EXF 2%SFS Blue EXF 2.4%

Recipe IISF Supra Yellow EXF 2.65 %SF Supra Red EXF 1.08 %SF Supra Navy Blue EXF 1.95 %

Recipe IIISFS Yellow EXF 2.35%SFS Red EXF 4.5%SFS Blue EXF 1.45%

SARADYE-R With Levafix

Fig.7 - Reactive dyeing using buffered alkali

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It is ideally available as liquid. We hadcome across many situations where peoplewould demand it in powder form, due totransportation costs and duties. Hence, wehave been able to develop this product inpowder form, ie. 100% Saradye-R (Conc),which can be very easily diluted and usedreadily.Core Alkali Neutralizer: Conventionally,acetic acid is utilised for neutralisation ofcellulosic substrates after alkalinepretreatment like bleaching, scouring,mercerising or after the dyeing stage.However, acetic acid evaporates at 100-102ºC and hence is no longer retained onthe substrate to neutralise any core alkali.This leads to a shift in pH of the substrate,thereby causing rejection of the fabric due topH of fabric extract. This shifting in pH alsoleads to several associated problems, suchas deteriorating fastness in long storage,and skin sensitisation. To overcome thelimitation of acetic acid, we have been ableto successfully develop a non-volatileproduct in stable powder from, Saracid-DV(Conc), which can be easily diluted and usedfor core alkali neutralisation in batch as wellas continuous operation. This is a non-corrosive neutralising agent, which does notaffect shade, tone or fastness properties.

FinishingPolyurethane: This is a new chemistry,based on blocked oligomeric isocyanate pre-polymers, which displays crease resistance,an anti-pilling effect and soft handle (Fig.8).We have developed Texpeach (Conc) at 60%strength and are also in the process ofdeveloping it in 80% strength. It gives a verygood handle as the product is a pre-polymer,contains no emulsifier and forms atransparent film on the fabric finished withit. Such products are normally available in30% strength. This product also improvesthe crockfastness of the fabrics finishedwith it and also imparts hydrophilic finishwith good drape. This can be added in DPfinish with resin, where resin quantity can bereduced to reduce strength loss withoutcompromising on DP rating.Hand Modifier & Sewability Improver: Thisis based on polyolefin chemistry to impartdurable soft hand, coupled with improvedsewability (Fig.9 & Fig 9(a)). Sarafinish-OE(Conc) can give open-end spun yarn the feelof ring-spun yarn (Open-end yarns aregenerally coarser and more hairy.) Suchproducts are normally available as 20%emulsions, whereas Sarex has developed

Sarafinish-OE (Conc) as a 60% emulsion.This is an ideal finishing chemical for cotton,polyester and polyester/cellulosic knits, asa softener as well as a raising or nappingassistant.Water Repellents: A 100% surfactant-freehydrophobic polyolefin self-emulsifiablesolid, Sarafinish-PH (Conc) imparts durablehydrophobicity on all types of substrates,showing excellent compatibility withstandard fluorochemicals. This can beideally used by formulators and processorswith good dilution facilities. Sarafinish-PH(Conc) gives excellent water repellency to allsubstrates as it is surfactant-free (Fig.10).Lubricant for Packages and Wet WaxingAgent for Yarns and Fibres: Generally theseare emulsions of paraffin waxes, mineraloils, silicone oil and short-chain alkyl esterswith nonionic or cationic emulsifiers, in the

form of 20-30% active emulsions. Yarnsoft-FRS (Conc) has been developed in the formof an 80% concentrate, which can be easilydispersible and can be effectively used forwet waxing of knitting, warp-knitting andweaving yarns. It can be applied by exhaustmethod or by the kiss-roll method (Fig.11).Ozone Fade Inhibitor: Indigo-dyed garmentsare affected due to atmospheric ozone andnoxious gases, leading to premature dullingor greying and yellowing of the goods, eitherin the warehouses or in the retail stores(Fig.12). This problem leads to a lot ofrejection. Generally ozone inhibitors areavailable as 20-30% emulsions. We havesuccessfully been able to develop 100%active anti-ozone fading agent and softener,Sarasoft-OZ (Conc), which can be diluted.Treated garments comply with AATCC-109 (2cycles) standard.

Fig. 8: General structure of a polyurethane

Fig.9 & Fig.9a: Performance of Sarafinish-OE (Conc) in improving sewability

Fig.10: Surfactant free water repellent

Fig.11: Treated Packaged yarn with Yarnsoft-FRS (Conc)

Fig.12: Mechanism of Ozone fading

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