NEWS

23

2024

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01

The whole process of textile printing and dyeing processing technology

1) Original cloth preparation: Original cloth preparation includes original cloth inspection, cloth turning (batching, boxing, printing) and sewing heads. The purpose of raw fabric inspection is to check the quality of grey fabric, and find that problems can be solved in time. The inspection content includes physical indicators and appearance defects. The former includes the length, amplitude, weight, warp and weft yarn density and density, strength, etc


1) Original cloth preparation: Original cloth preparation includes original cloth inspection, cloth turning (batching, boxing, printing) and sewing heads. The purpose of raw fabric inspection is to check the quality of grey fabric, and find that problems can be solved in time. The inspection content includes physical indicators and appearance defects. The former includes the length, amplitude, weight, warp and weft yarn density and density, strength, etc., while the latter includes spinning defects, weaving defects, various class stains and damages. Usually about 10% of the total number of random inspections. After the original cloth is inspected, the original cloth must be divided into batches and boxes, and printed on the cloth head, indicating the variety, processing technology, batch number, box number, release date and cloth turning person code for easy management. In order to ensure continuous batch processing, the raw fabric must be sewn.

2) Singeing: The purpose of singeing is to burn off the fluff on the cloth surface, make the cloth surface smooth and beautiful, and prevent uneven dyeing and printing defects due to the presence of fluff during dyeing and printing. Fabric singeing is to quickly pass the flat width of the fabric through the high-temperature flame, or rub the red-hot metal surface, then the fluff existing on the cloth surface quickly heats up, and burns, and the cloth body is relatively tight, the temperature rises slowly, and when it does not rise to the ignition point, it has left the flame or red-hot metal surface, so as to achieve the purpose of burning off the fluff and not operating the fabric.

3) Sizing: In order to weave the fabric smoothly, textile mills often sizing the warp yarn to improve the strength and wear resistance. The slurry on the grey cloth affects the water absorption performance of the fabric, and also affects the quality of dyeing and finishing products, and will increase the consumption of dyeing and chemical drugs, so the slurry should be removed before scouring, and this process is called desizing. The slurry on the cotton fabric can be removed from the fabric by alkali desizing, enzymatic desizing, acid desizing and oxidant desizing. Alkali desizing puffs the slurry, reduces the adhesion with the fiber, and is removed from the fabric after washing. Enzymes, acids, and oxidants degrade starch, increase solubility in water, and are washed away by water. Due to the great damage of acid and oxidant to cotton fiber, it is rarely used alone, and is often used in combination with enzyme desizing and alkali desizing

4) Scouring: When cotton fibers are grown, they are accompanied by natural impurities (pectin, waxy substances, nitrogenous substances, etc.). After desizing the cotton fabric, most of the slurry and some natural impurities have been removed, but there are still a small amount of slurry and most of the natural impurities still remain on the fabric. The presence of these impurities makes the cloth surface of the cotton fabric yellow and the permeability is poor. At the same time, due to the presence of cottonseed husks, the appearance quality of cotton cloth is greatly affected. Therefore, it is necessary to quench the fabric in a concentrated lye at high temperature for a long time to remove residual impurities. Scouring is the use of caustic soda and other scouring additives and pectin, waxy substances, nitrogen-containing substances, cottonseed husks to undergo chemical degradation reactions or emulsification, puffing, etc., after washing to remove impurities from the fabric

5) Bleaching: After the cotton fabric is scoured, due to the presence of natural pigments on the fibers, its appearance is not white enough, and it will be used for dyeing or printing, which will affect the brightness of the color. The purpose of bleaching is to remove the pigment and give the fabric the necessary and stable whiteness without significant damage to the fibers themselves. The commonly used bleaching methods for cotton fabrics include sodium hyponitrite, hydrogen peroxide and sodium chlorite. The PH value of the bleaching liquid of sodium hypochlorite bleaching is about 10, which is carried out at room temperature, the equipment is simple, the operation is convenient, and the cost is low, but the strength of the fabric is damaged greatly and the whiteness is low. The pH value of the bleaching liquid of hydrogen peroxide bleaching is 10, and the bleaching is carried out at high temperature, the bleached fabric has high and stable whiteness, good hand feel, and can also remove slurry and natural impurities. The disadvantage is that the equipment is demanding and the cost is higher. Under appropriate conditions, combined with caustic soda, it can make desizing, scouring and bleaching complete at one time. The PH value of the bleaching liquid of sodium chlorite bleaching is 4~4.5, which is carried out at high temperature, which has the advantages of good whiteness and small damage to the fiber, but it is easy to produce toxic gases during bleaching, pollute the environment, and corrode equipment. Both sodium hypochlorite and sodium chlorite are dechlorinated after bleaching to prevent damage to the fabric due to the presence of residual chlorine during the present process

6) dyeing dyeing is a more complex process, different quality of cloth dyeing process is different, cotton, polyester cotton, linen cotton, woolen wool, silk products, chemical fiber products, blended products, and so on, some use pad dyeing, roll dyeing, some must use high temperature and high pressure dyeing, some only dyeing once, some to color many times. There are also different processes for using different dyes, just take the basic cotton cloth as an example: Although dyeing can be done through a rolling car, it is also the most difficult process, because in addition to the known color control of dyeing, there are many unknown things in it, such as the stability of the dye at different temperatures, the control of steam, the control of rolling pressure, etc., are all very delicate work. 。 The dyed long car is divided into two parts, the front car is dyed and the rear car is fixed. The dyeing method is different according to the different types of dyes selected, and the dyes are generally active, Shilin, vulcanization, and coatings. They have their own advantages and disadvantages, generally depending on the required color, and can not be replaced with each other, among them, the color fastness of Shilin is the best, but the price is expensive, not suitable for dyeing dark colors, light colors are not bright enough. In addition to the cost of dyeing dark colors, there are also relatively reactive dyes that dye dark colors are difficult to control, and they are prone to cloth flowers. The color fastness of the activity is worse than that of Shilin, but the light color is more gorgeous, the dark color is easy to control, and the cost is correspondingly less. The vulcanization is the worst, the color fastness is not very good, and the forbidden AZO is not up to standard, but now there is a liquid vulcanization (also called water vulcanization) forbidden AZO can meet the standard, but the price is close to Shilin, the dyeing is not easy to control and can not be popularized, only a few people pursue its fading effect and use. The paint is not comparable, and its fading is very serious, which is the best choice for the pursuit of fading effect after washing the garment. It can be flexibly applied with Shilin and active to obtain different washing effects (general Shilin or active primer, paint cover surface color, can solve the problem of white spots in single-dye paint, and the cost increases accordingly). The activity, Shilin and vulcanized dyeing front car are basically the same, to say the difference, is that the infrared pre-baking open one group, two groups or no open. The rear car is completely different. The active one uses salt and soda ash to fix the color, the one of Shilin uses hydrogen peroxide to reduce the color (so Shilin is also called vat dye), and the vulcanized one needs to be cooked at high temperature to fix the color, and the water temperature must be above 95 degrees. After the dyeing of the paint, it is decided whether to bake and fix the color according to the fading requirements of the color fastness. The baking temperature is about 195-210 degrees. Dyeing can not be 100% good, color repair, color peeling is inevitable. Slight adjustments such as a shallow set of paint, deep wash with soda ash.