Wool fabric Jingxi it, the vast majority of impurities have been removed, but often with a little wool and natural pigments, even if it is white wool, also with a pale yellow. To obtain pure white fabric, must be bleached to remove these pigments. Fabric bleached, except requires a certain white-givers, also called application easy storage yellowing, fabric whiteness and stability should be the second set. In order to improve the whiteness of some products need to be brightening. Wool and wool fabrics are oxidation products of bleaching bleaching, reduction bleaching. Oxidation can use hydrogen peroxide bleaching, sodium hypochlorite, potassium permanganate and other oxidizing bleach. Commonly used for hydrogen peroxide, the mechanism of hydrogen peroxide decomposition by the oxygen out of the new organic pigments containing wool damage. With hydrogen peroxide bleaching characteristics: good whiteness, more durable, easy to yellow; but wool has some damage. Hydrogen peroxide with the excessive, over-oxidation of the fiber, easy to make fabric feel rough, strong decrease. Bleaching methods are dipping method and the steam drift drift and French. Baptist bleaching method is to dip the wool hydrogen peroxide solution, temperature 50 ℃, dipped drift time 10 ~ l5h, pH = 7.5 ~ 8, bleach pigment concentration as the fiber content may be. Bleach solution or ammonia additive sodium silicate and acid. Bleach solution on certain metal ions such as copper, iron, manganese, etc., or metal shavings are a catalyst, easy to make holes in the fabric occurs. Sodium silicate is generally added as stabilizer. Steam bleaching wool padding method is the concentration of 0.3% ~ 0.9% hydrogen peroxide solution, pH = 3 ~ 5, and then drying in the 95C of the chamber in, you can achieve the purpose of bleaching. Reduction is the use of reductive bleaching of wool in the color of the pigment reduction Ershi disappear. This bleaching effect on wool damage, but after a long period after bleaching susceptible to oxidation in contact with air, and yellow. Reduction of cold white agents are sulfur dioxide, sodium hydrosulfite, sodium bisulfite, hair bleaching powder, carved white block and so on. Industry hair bleaching powder is used, its main component is 60% and 40% sodium hydrosulfite mixture of sodium pyrophosphate, water-decomposition of new eco-hydrogen, since [H] has a strong reducing power, the natural pigment can reduced to leuco Ershi become white wool. This bleaching method for wool less damage, but poor light fastness. Hair bleach powder, it will enlarge to 40 ℃ 309 wool drift a few hair powder solution, turned over once every 0.5 ~ lh to function fully. Treated with water wash, and then drop off immediately by the sulfuric acid washing, dehydration, and dry. If used for wool fabric bleaching, thin wool fabric with the bleaching powder 19, a few, some 59 heavy fabric, bleaching liquid temperature does not exceed 45 ℃. Require high whiteness can be used twice bleached wool fabric, this method is first bleached by oxidation and then reduction by random drift it is known as double. Wool fabric after bleaching by the two-lasting whiteness of white, shiny looking, easy to yellow, feel good, less strength loss for worsted wool fabric bleach. Some examples are as follows: pure wool worsted fabrics.
① prescription bleaching oxide: hydrogen peroxide (30%) 15mol / L, ammonia 0.3% 1 0.5% operation: 30C when adding hydrogen peroxide, after 20min heating up to 50C, heat l0min, joined ammonia to continue holding 90min, floating completion, cool wash to free up the residual hydrogen peroxide.
② Reduction of bleaching Prescription: Bleaching powder 12% Wool 18%, brightener WG0.2% 1 0.7%. Operation: 30 ℃ hair bleaching powder when joined, brightener solution, in 45 ~ 5Omin heated to 75 ℃ in a 80 ℃, thermal bleaching 60min, float finished cleaning out the machine cool.
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