Chemical Finishing and Washing of Knit Wear
Chemical Finishing and Washing of Knit Wear
Chemical Finishing and Washing of Knit Wear
By: Dr. N. Gokarneshan, Prof. Durairaj, C. Krishnamurthy, P. Shanmugasundaram, S. Subhash, R. P. Subasree & E. Saranya
For reactive softer, put the fabric into water bath for 2 mins pad the sample with 5 bar pressure. Put the sample into the softening bath for 3 mins. After the duration of 3 mins, pad the sample with 3 bar pressure and then dry. Silicon Softening Silicone may be applied to various types of fibre materials. Silicones emulsions are one of the versatile chemicals for different fibres. They impart water repellency, soft handle and improved draping qualities to acetate rayon, viscose rayon, and nylon fabrics, some of them make the treated fabric stain resistance too. Fabrics are treated with them to give longer life, better abrasion resistance and a softening effect, all of which are durable to laundering and dry cleaning some of them have been successfully applied to texturised 100% polyester, and polyester blend knits, textures polyesters woven fabrics, durable press - finished woven fabrics of polyester cellulosic blends. The finish is applied by the pad-dry-cure technique, either alone or in conjunction with resin pre-condensates and cross linking agents. Improved dry and wet wrinkle recovery, improved hand, which can be varied from dry and crisp to soft and luxurious, durable stain resistance and improved tear strength are claimed. Since most silicones are oily in nature and are not soluble in water, emulsion techniques are employed to prepare a suitable aqueous system. This is readily accomplished by use of employed to prepare a suitable aqueous system. This is readily accomplished by use of emulsifying agents. In selecting a suitable emulsifier, it must be kept in mind that any compound having high wetting and rewetting properties, must be avoided since such an agent will tend to nuIIify the water - repellent characteristics of the finish. Generally, silicones oils which are used in the form of 30% or 40% emulsion are used extensively in textile processing. These, emulsion should be suitably diluted depending on the original concentration before using on the padding mangle. The squeezing ratio or the expression of the mangle should also be considered in calculating the final deposit of silicones on the fabric. Important factors in the application of silicones are as follows 1. Fabric to be processed must be thoroughly cleaned and should contain no residual agents from the scouring or dyeing operations. The ph of the cloth to be treated is preferably in the range of 6-7. 2. The fabric must be processed in such a way as to obtain through and uniform impregnation in order to pick up the required amount of silicones from the treating bath. This is usually done on conventional mill equipment such as a padder equipped with squeeze rolls.
3. Following impregnation, the fabric is dried and then subjected to high temperature curing. Under the influence of curing temperature, some of the silicone linkages. The silicone "skin" thus formed then becomes insoluble in both water and the common dry- cleaning solvents. In order to develop satisfactory durability, it is essential to introduce a catalyst in the silicones emulsion system. Generally, salts of zinc, tin and zirconium are used as catalysts. 4. The general recommended temperature are as follows 8-1 minutesat130c Or 3-5 minutes at 150 c Or 1-2 minutes at 170 c The padding the fabric is dried at 100-120 c and then it is cured at recommended temperature as above. Properties imparted to textiles 1) 2) 3) 4) 5) 6) 7) It gives water-repellency effect Improved in abrasion or wear resistance, tear strength and sewing qualities It produces soft and smooth feel The fabric attains more flexibility It is resistance to solvent and washing The treated fabric does not wrinkles or shrinks as badly
Use of silicones in finishing (Special finish) Silicones are one of the most important organic polymers which play a major role in textile industry. Without silicones, fabric finishing wiII be incomplete. 1. Silicones are used in all textiles processes from spinners to finishing sewing thread and from foam control to finishing of the fabric. 2. Silicones are used as softeners in the finishing stage of textiles processing. Softening agents are applied to improve softness, lasting elasticity, body, soft handle sewing qualities of the fabric. 3. Silicones are used in any type of finishing processes like padding, exhaustion, spraying etc.; they are suitable with other agents like resins, optical brighteners, binders, catalysts etc 4. It must impart softeners, lubricity to the treated cloth and reduce static buildup, especially in the case of hydrophobic fibers like nylon, polyesters, acetate and acrylic. Subsequently the fiber must not loss its brightness or its quality. 5. Silicone based softeners impart softeners and fullness to he woven fabrics, manufactured from ring or open end spun yarns. Softening and fabric enhancement effect of silicones is maintained even after multiple launderings and dry cleaning unlike other softeners whose effect is temporary. 6. Silicones, as antifoams, destroy foam formed in all the processing, bleaching, mercerizing, dyeing, finishing and even in the waste water treatment.
The silicones, as deformer, added to the jet dyeing both for effective deforming enable the fabric to be dyed uniformly. Paraffin wax, vegetable wax, silicon emuIsionete. Recipe and process details CERALVBE INF Padding pressure Padding pressure : 70gpl : Water pading : Softening padding
: 5 hour : 3 hour
For silicon softer, put the fabric into water bath for 2 mins pad the sample with 5 bar pressure. Put the sample into the softening bath for 3 mins. After the duration of 3 mins, pad the sample with 3 bar pressure and then dry. Acid wash It is produced by washing with chemically treated pumice stones. It is also known as Ice Washed (or) chemical wash. Chemicals used Potassium permanganate - 1.5-5% Conc. (1-2hrs.) Sodium hydrochloride - 2 gpl avl. C12, pH-l 0 (60-90min) The following problems are encountered With KmN04 Method It is done by tumbling the garments with pumice stones presoaked in a solution of sodium hypochlorite or potassium permanganate for localized bleaching resulting in a non uniform sharp blue/white contrast. In this wash the color contrast of the denim fabric can be enhanced by optical brightening. The advantage of this process is that it saves water as addition of water is not required. Tonal changes Residual manganese 1 00 ppm) Dingy garments - Red Brown spots Cleaning the machine with NaOCI Difficult to standardize process Varies with soaking time, concentration, pH, moisture content, time of treatment.
Acid wash is a cool and pretty way of making a fabric different from average jeans. It was started in the mid'80's by the Italian company Rifle Jeans, and it has grown and sunk in popularity over time. It remains an active style for jean designers and purchasers. This should be done in a professional setting, and the following procedure needs to be followed 1) Buy porous pumice stones. These will play an important part of the dying process so you want to make sure that you get ones that wiII be effec1ive. Beauty stores, as well as sites like ebay, carry pumice stones regularly. 2) Soak the pumice stones in chlorine. See the link below for the complete safety instructions on handling chlorine. 3) Get access to two industrial washing machines. This can present quite a challenge. By looking in the yellow pages and calling around, you can find a facility that will assist you in this. I have included a couple of links below to help in your search as well. Never, under any circumstances, do you want to perform this process in a regular washing machine designed for home use. 4) Load the jeans and the stones into an industrial washer. You also want to avoid the fumes, and warn others of the same, when acid washing jeans. Leave the premises momentarily. 5) Check on the jeans after 15 minutes. The typical time it takes is 25 minutes, but you want to check to make sure. You don't want to go too far in either direction with acid washing. Too little can make a fabric look awful, and over-doing it can destroy a great pair of jeans! 6) Keep checking every ten minutes after that for just the right look! 7) Once the jeans are dyed to perfection, they should be transferred to another machine, and have "antichlor", sodium bisulfite, added to water they are washed with. Only a tablespoon of sodium bisulfite is necessary. Leave them washing for five minutes in this process. This will remove any remaining chlorine. 8) Wash jeans in water for five minutes more to remove any grit from the stones and any possible remaining chlorine. 9) Put the jeans in a high-powered drier until all dry! You now have completed the process of acid washing. 10) Try an easier approach if you are not in the garment industry. Experiment with your clothes by spraying beach in patches on a pair of jeans (not your good ones, these are for experimenting). Leave on for five minutes, then wash. This creates a unique look. Perhaps that sort of thing is what you are craving with the "acid wash" look. Precautionary measures Try on a pair of jeans before and after they are acid washed. You'll find the jeans will likely to be more comfortable after the wash, and they will feel more broken in. Ask for the opinion of others when deciding on how much on acid wash look you'd like for your jeans. Never instruct or let a child do this! Beware of all chemicals in your household, and ask your city how to properly dispose of them in your area. Don't try this in a home machine or at a laundry mat. The machines can get seriously damaged by the stones or chemicals Never use a chemical without thoroughly research the hazards and safety for your personal use.
Enzyme wash It is environmentally friendly wash. It involves the application of organic enzymes that eat away at the fabric, i.e. the cellulose. When the desired color is achieved, the enzymes can be stopped by changing the alkalinity of the bath or its temperature. Post treatment includes final rinsing and softening cycle. The effects produced by the cellulose enzyme are: 1. Use of cellulase making the seams, hems, and pockets more noticeable 2. Salt pepper effect is color contrast effect. 3. Faded garment with acid cellulase enzyme provides less color contrast in proportion to garment washed with neutral cellulase enzymes. 4. Garment load size of the machine is 35-40 jeans per machine and it cannot be overloaded.
Conclusion This article highlights the different types of softening and washing treatments suitable for knit goods. The merits and limitations of the various softeners are discussed herein. Reactive softeners are not easily applicable to cellulosic materials while silicone softeners are versatile and also have marked positive effects on the knit materials. Acid washes though suitable for knit garments, need to be done with precautions. Enzymatic washes are more advantageous as they are eco friendly and eliminate the risk of water pollution and also enhance the garment appearance in certain ways. References 1) Effect of enzyme softening of cotton hosiery yarns on knittability and dimensional properties of weft knitted fabrics, Bhaarathi durai and v. Natarajan, Indian journal of fibres and textile research, June 2007, p.241. 2) Effects of biofinishing on cotton/wool blended fabrics, S. V. Chikodi, S. Khan, & R. Mehta, Textile research journal, p.264. 3) New developments in the chemical finishing of textiles, Holmes, Journal of the textile institute, 1993. 4) Influence of household fabric softeners and laundry enzymes on pilling and breaking Strength, A. Chiweshe & P.Cox crews, AATCC review, September 2000, pAl. 5) Knitters review forums, October 2005. 6) Method for enzymatic treatment of wool, USP 6051 033. About the Authors The authors are associated with NIFT TEA College of Knitwear Fashion, Tiruppur Originally published in Textile Review; July 2009