Desizing process

The choice and combinations of different size components must take account of many factors if optimum results are to be obtained. Much has been published regarding the optimisation of size formulations in relation to desizing processes [177-183]. Cotton warp yarns sized with starch are normally woven at high humidity (80% and above) to keep yarn breakages low, as the starch film is brittle at low humidity. It has been shown [183], however, that improved weavability at moderate relative humidity (e.g. 65%) can be obtained using (a) starch/acrylamide or hydroxyethyl starch at not less than 15% add-on or (b) poly(vinyl alcohol), which gave excellent results even at a low add-on of 5-6%. 

Analysis and monitoring of size polymers and desizing processes... 

If LEONIL EB is used, a separate enzymatic desizing process can usually be omitted, thus effecting considerable savings in time, energy and water. 

Recently a cold desizing process using sodium sulphide in a weakly alkaline solution is reported [23]. The rate of desizing is increased 5-fold compared with alkali alone. A mechanism involving a catalytic effect of the sodium sulphide in the hydrolysis of glucoside bonds in the polysaccharide is proposed. 

Figure 3-14. Continuous solvent desizing process (Courtesy of ICI Mond Division, England).

ScrviUte. [Cheidoid] Dyebath bleaching agentsandstatMlizersftM-hydrogenper-( ide bleac g and desizing processes. 

ServiUte. [Chendoid] Dyebadi bleaching agentsandstabilizetsftirhydrogenper-coide Ueachti and desizing processes. 

The cotton yarns sized with various polymeric sizing agents were provided by Southern Regional Research Center, U.S. Department of Agriculture. These yarns had been sized on a laboratory single-end-slasher. Portions of the sized yarns also had been subjected to a desizing process involving a boil-off with 0.5 sodium hydroxide. 

Enzymatic methods Many research organizations and scientists are working to improve the environment-friendly processing of cotton fabrics with enzymes. The many enzymes are today available for the removal of Impurities in the cotton fibers. For example, alpha amylase is enzyme used for cotton desizing process, pectlnase for pectin removal in cotton fiber and lipase, and protease for fatty substance removal in the cotton fiber treatments. Typical textile wet processing of cotton materials is shown in Fig. 4.6. 

The application of enzymes in food processing, in the paper and leather industries, as additives in washing powders, and in the desizing process of cotton is well established. However, biocatalysis has also entered textile processing. Enzymes, biocatalysts with specific and selective activity, are today produced by biotechnological processes in great amounts and constant quality, and are therefore applicable to large-scale processes. 

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