Three bleaching methods for high-grade knitted spandex cotton fabric

2019.09.25SOURCE:

Three bleaching methods for high-grade knitted spandex cotton fabric
After the cotton fabric is scoured, the impurities are obviously reduced, and the water absorption is greatly improved. However, due to the presence of natural pigments on the fibers, the appearance is not white, in addition to dyeing dark varieties, bleaching is also required to improve the uniformity of dyeing and the vividness of color, especially for white fabrics.
(1)Bleaching purpose: The purpose of bleaching is to destroy the pigment, improve the whiteness, and further remove residual cottonseed shell, pectin and other impurities to improve the water absorption of the fabric.
(2)Bleaching agent The oxidizing agent used for cotton fabric bleaching mainly includes sodium hypochlorite, hydrogen peroxide and sodium chlorite. The processes are called chlorine bleaching, oxygen bleaching and sub-bleaching, respectively.
Sodium hypochlorite bleaching is low in cost and simple in equipment, and has been widely used for bleaching cotton knitwear. However, the bleaching effect of sodium hypochlorite is generally lower than that of bleaching fabrics. The whiteness and whiteness of the bleaching fabric are less than that of hydrogen peroxide and sodium chlorite, and the fiber damage is large. Dechlorination after bleaching will not affect the dyeing of dyes, especially for reactive dyes. Large, bleaching waste liquid is very polluting to the environment, so sodium hypochlorite bleaching is gradually being replaced by chlorine bleaching.
The bleaching effect of hydrogen peroxide is good for fiber damage, wide variety adaptability, small environmental pollution, and good removal ability for other natural impurities. It is currently the most important bleaching method.
Although there are many advantages of sodium chlorite bleaching, the whiteness of bleaching is good, durable, non-yellowing, less damage to fiber, strong ability to remove impurities, can dissolve lignin and pectin, can be directly bleached without scouring, and can be better preserved. The waxy substance on the cotton fiber is soft to the touch, has good elasticity, and has wide adaptability to the variety, and has a good bleaching effect on the synthetic fiber.we are spandex cotton fabric manufacturers and  spandex cotton wholesale,we can guarantee quality.
However, sodium chlorite bleaching has high cost and is highly corrosive to equipment. The chlorine dioxide toxicity conference caused by bleaching seriously damages workers' health and seriously pollutes the ecological environment. So sodium chlorite bleaching will gradually be banned.
The process conditions must be strictly controlled during the bleaching of the cotton knit fabric, otherwise the fibers will be oxidized and damaged.

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