Jeans washing and finishing technology has developed from traditional rinsing, stone milling to enzymatic washing and stone milling. Nowadays, acid cellulase enzyme liquid
stone milling, biological polishing and non-ironing finishing of pure cotton clothing are more popular. The formulation of acid cellulase enzyme liquid is described as follows.
Acid cellulase enzyme liquid
is fermented by a single fungus strain. It can hydrolyze the surface of cellulose and partly produce water-soluble products such as short-chain polysaccharides and glucose. Because the dyeing and finishing of denim is only on the surface of fibers, cellulase partially hydrolyzes the surface of cellulose while removing the dyes attached to the surface of fibers. According to the requirement of pH value of water bath in the process of stone mill washing, cellulase was divided into acid cellulase and neutral cellulase. The optimum pH value of acid cellulase is 4.5-5.5 (sensitive to pH value, low price). The optimum pH value of neutral cellulase is 6-8 (stable for pH value and high price).
Process conditions: Acid cellulase enzyme liquid 1.0%-1.5% (for clothing weight), pH 4.5-5.5 (acidic enzyme), treatment time 45-120 min, temperature 50-60C, pumice dosage 0-0.5kg/kg clothing (depending on the old degree), bath ratio 1:10-15. Using cellulase to wash with stone mill can greatly reduce the amount of pumice (only about 25% of the original amount of pumice), or even do not need pumice. At the same time, it can increase the washing capacity of the washing machine and reduce the environmental pollution. Due to the reduction of pumice grinding on the clothes, the washing clothes feel soft, natural and bright. In the process of stone mill washing, the indigo dyestuff falling off in the water bath has obvious re-staining phenomenon below the pH of 6, which results in the blue of insertion thread and inner pocket material in jeans seam, and the blue/white contrast style decreases. When the pH is above 7 in the water bath, the phenomenon of back staining will be significantly reduced. Acid cellulase enzyme liquid can be used in low-grade and various stone mill rinsing processes.