The Preparation Of Cotton Canvas With Low Temperature And Without Alkali

Enzyme scouring and low-temperature bleaching meet the requirements of green production and sustainable development in the pretreatment of cotton fabric, which go with the time's request of high efficiency, environmental protection and water & power saving, so they have a bright future. This research mainly studied on the pretreatment of cotton canvas with enzymes and bleaching without alkali, and preliminary probed into the mechanism of enzymatic scouring. It has practical significance in promoting the implementation of pretreatment of cotton fabric in the process of "energy-saving, consumption and emission reduction".Alkaline pectinase and neutral cellulose were used as the scouring agents. The scouring process of each single enzyme was studied firstly, then the compound of these two kinds of enzyme was investigated using their biocompatibility and cooperativity. Through single-factor and orthogonal methods the optimal enzyme souring process was obtained. The scouring process was done through 60min in the condition of 50-60℃and near neutral pH, which was energy-saving and comprehensive low-cost. Compared with traditional alkali scouring, the enzymatic souring cotton fabrics had less strength loss and had smooth surface and soft handle with a considerable wetting and dyeing properties, superior to the traditional alkaline scouring, only the whiteness was a little lower.The removal of impurities and the morphological changes of cotton fiber through bioenzyme scouring were analysed by FT-IR ATR spectroscopy and scanning electron microscopy separately. Alkaline pectinase could effectively remove pectin, but the wax removal effect was poor, even with the emulsification of the surfactant. Neutral cellulase etched the primary cell wall of cotton fiber, and the wax removal effect was obvious, with the removal of pectin partly. Compound enzyme souring did better in the removal of pectin and wax, and the surface of the treated fiber was smooth.Through single-factor and orthogonal experiments studying on the concentration of H₂O₂ , stabilizing agent and pH value, the optimal combination of the peroxide bleaching without alkali after the compound enzyme souring was obtained. Trough discussing the factors of H₂O₂/TAED system, such as H₂O₂ concentration, TAED concentration, tempreture, time, pH value and stabilizing agent, the optimal low-temperature bleaching system of H₂O₂/TAED after the compound enzyme souring was obtained. The removal of impurities, whiteness and wetting property of the treated cotton fabric were good. High temperature non-alkali peroxide bleaching process was higher in H₂O₂ concentration (8g/L) and tempreture (98℃), and the strength loss of the bleached fabric was a little higher and small cracks appeared on the fiber surface. While low-temperature bleaching process (H₂O₂ 4g/L, temperature 70℃, pH value 8, time 40-60min) had an obvious effect on energy-saving and emission reduction, and the bleached fabric had better dyeing performance and less strength loss, and there was no obvious damage on the fiber surface.The feasibility of one-bath pretreatment of cotton fabric with enzymes and peroxide was analyzed , the optimal one-bath low-temperature pretreatement process was obtained as follows: pretreatment with hot water of 95℃for 10min, alkaline pectinase 1.5g/L, neutral cellulase 0.8gL, H₂O₂ 4.0g/L, TAED 13.4g/L, sodium pyrophosphate 3.0g/L, NW800 1.0g/L, liquor ratio 1:20, pH value 8.0, firstly treated in 55℃for 60min and then warming to 65℃and dealing with 20-30min. The process was water and energy saving. The whiteness, wetting and dyeing properties, the removal of impurities of the treated fabric were good, and the strength loss was smaller, the fiber surface was smooth.