Waterless and water-less textile pre-treatment technology
Waterless and water-less textile pre-treatment technology
(1)Low temperature plasma technology
Plasma treatment of fabrics has many advantages, such as improving wettability, improving the adhesion of coating, dipping, and gluing condensation treated fabrics, improving fiber dyeing yield, color fastness and printed fabric quality, and No water or chemicals required.
The DPR plasma equipment launched by Italy’s H.T.PUNITEX has been successfully used in the desizing process of open-width fabrics. The nominal width of the equipment is 500-3500mm, and the nominal speed is 5-5Om/min. The basic principle is to use the plasma (temperature: 50°C) generated by the electrode in a vacuum (20-200Pa), nitrogen-filled container to desize the fabric. Plasma can effectively cut off the molecular chains of the sizing on the fabric, which not only improves the dyeing rate and color fastness, but also greatly shortens the process of pre-treatment washing equipment, saves ice and air, and reduces waste liquid discharge. The Textile Engineering Department of Minho University in Portugal conducts plasma corona discharge treatment and then mercerization before mercerizing cotton fabrics. Using the corona discharge device used in Softal electronic laboratory, in the air system, the frequency is 40kHz, the voltage between the two electrodes is 10,000V, and the dry cotton fabric is subjected to plasma corona discharge treatment at normal temperature and pressure, and then Under tension-controlled conditions, cotton fabrics were mercerized with a NaOH concentration of 300g/L. The time for cotton fabrics treated with corona discharge to absorb NaOH is significantly shortened, and the stronger the discharge, the faster the fabric absorbs NaOH. This is attributed to the increase in oxidation potential and the grooves created by the cotton fiber skin layer. Likewise, the mercerized barium value of plasma-treated fabrics is higher than that of gray fabrics or desized and bleached cotton fabrics. After corona discharge pretreatment, no wetting agent is needed during mercerization, so it is easier to recycle NaOH, the cost is lower, and it has little impact on the environment.
The biggest advantage of the APPS plasma treatment prototype jointly developed by the Shanghai Institute of Textile Science and Pacific Printing and Dyeing Machinery Co., Ltd. is that it can perform continuous plasma treatment under normal pressure conditions, which reduces the difficulty of manufacturing and control. At present, gratifying progress has been made in wool processing, and continuous plasma desizing equipment suitable for large-volume and wide-area open-width fabrics is being developed.
(2) Ultrasonic pre-treatment technology
Ultrasound is a vibration wave that cannot be detected by human hearing, with a frequency of 2×104-2×108Hz. The application of ultrasonic waves in pre-processing can increase the processing speed.
During the desizing and scouring process, the dispersion caused by the cavitation of ultrasonic waves causes separation between macromolecules, promoting the loosening of the adhesion between slurry, impurities and fibers, and the emulsification of ultrasonic waves can improve the separation of slurry and impurities. solubility. Due to the endothermic effect of ultrasonic waves, energy can be provided for reactions maintained at a certain temperature. The use of ultrasonic desizing can reduce fiber degradation, and the whiteness and wettability are equivalent to traditional alkali treatment. Using ultrasonic waves to bleach cotton fabrics with hydrogen peroxide, it was found that the bleaching speed was increased, the bleaching time was shortened, and the fabric whiteness was also better than traditional bleaching methods. Bleached cotton fabrics treated with ultrasonic waves are also very effective for dyeing direct dyes and reactive dyes.
Although ultrasonic pretreatment has the advantages of saving water, energy, and time, there are still many problems that need to be solved if it is to be used in industrial production, such as processing costs, ultrasonic directionality, noise, and other issues. 4xkrb6Z4X
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