DESIZING
- 1. ALLPPT.com _ Free PowerPoint Templates, Diagrams and Charts WELCOME TO MY PRESENTATIO N ABOUT DESIZING NAME:NITHAI PAUL ID:105/18 LEVEL-2,TERM-2
- 2. Desizing: It is the process of removing the Size material from the warp yarns in woven fabrics to facilitate the process of weaving. Sizing agents are selected on the basic of type of fabrics.. Desizing is an essential stage of all textile processing, in which ‘size’ is removed from fabric before completing the pre-treatment process, which is necessary before dyeing, printing and finishing.
- 4. Where does the size come from? Before yarn is converted into fabric, the ‘Warp’ yarns are coated with sizing agents which decreasing breakages on the loom and improves productivity. However the sizing agents often resist the dyes and chemicals commonly used in textile processing, so they have to be thoroughly removed before any wet processing can take place.
- 7. Acid Desizing: Cold solutions of dilute sulfuric or hydrochloric acid s are used to hydrolyze the starch. however, this h as the disadvantage of affecting the cellulose fiber in cotton fabrics
- 8. Enzymatic Desizing: Enzymatic desizing is the classical desizing process of degrading starc h size on cotton fabrics using enzymes. Enzymes are complex organic bio-catalysts, formed by living organisms, that catalyze chemical reacti on in biological processes. A small quantity of enzyme is able to decom pose a large quantity of the substance it acts upon. Enzymes are usuall y named by the kind of substance. Amylases is the enzyme that hydrol yses and reduces the molecular weight of amylose and amylopectin in starch.
- 9. Desizing on a jigger: It is a simple method where the fabric from one roll is processed in a bath and rewound on another roll. Fir st, the sized fabric is washed in hot water (80-95°C). The desizing liquor is then adjusted to pH 5.5-7.5 . The amylase is added in an impregnation stage and degraded the starch in the form of dextrin's. Then re moved by washing two minutes. The jigger process i s a batch process. In the reaction time for the enzym e may be as little as 15 seconds.
- 10. Oxidative Desizing: In oxidative desizing, the risk of damage to the cellulose fib er is very high, and its use for desizing is increasingly rare. Oxidative desizing uses sodium or potassium sulphates or sodium bromite as an oxidizing agent.
- 11. Factors of Size Removal Efficiency: The factors on the efficiency of size removal depe nds, are as follows: 1.Type and amount of size applied 2.Viscosity of the size in the solution 3.Nature and the amount of the plasticizers 4.Fabric construction 5.Method of desizing 6.Method of washing.
- 12. Method of testing: 1.The more scientific method is One or two drops of the solution are put on the desized fabric and rubbed gently. In a s hort time the color of the spotted area changes. The change in color is assessed visually. 2.The weight loss can be used as criteria for testing of desizin g efficiency. The weight loss is of the order of 7-10%.