Practice bleaching process

(1) Desizing process: Printing and dyeing plants generally use mercerizing light alkali or biological enzyme as a desizing agent. In addition, penetrants, chelating agents and other additives shall be added to make up the desizing agent. After the gray cloth is immersed in the desizing solution, they are steamed or stacked at room temperature to ensure the required process conditions for desizing. After steaming or stacking, the puffed slurry on the fabric must be washed thoroughly with hot water to achieve the purpose of removing the slurry.

2) The scouring process: The scouring liquid formula usually contains a main agent (caustic soda) and a training aid (penetrant, emulsifier and soda ash). The fabric padding scouring liquid is usually steamed for 45-65 minutes under a saturated steam condition of 100 degrees or more, and then fully washed to remove the decomposition products in the scouring process. The current scouring enzyme has partially replaced caustic soda as a scouring agent in some printing and dyeing plants, and the scouring effect is also good. However, the cost of this new process is too high, the process is still not fully mature, the activity of biological enzymes is not stable enough, it will affect the scouring effect, so that its popularization and application are subject to certain restrictions. However, we still hope that breakthroughs will be made in the research and development of bio-enzymatic technology. This should be the development direction of the bleaching and bleaching process.

3) Bleaching process: From the 50th to 70th century in the 20th century, bleaching agents commonly used in the bleaching process belonged to sodium hypochlorite, and they were widely used in rope combined bleaching and bleaching units. The advantage of this process is that it can be bleached at room temperature. Sodium hypochlorite is simple to produce and low in cost. However, this process is not environmentally friendly and has an impact on the environment. It has now been eliminated and is now only used in a small amount for the bleaching of linen-cotton blended fabrics. At present, bleaching agents widely used in printing and dyeing plants are safe and environmentally friendly hydrogen peroxide. The formulation of bleaching liquids is mainly composed of hydrogen peroxide, stabilizers, and chelating agents. After the cotton fabric is bleached and bleached, it is usually steamed in a saturated steam of 丨001 or higher to 404050“0, and fully washed with water to remove the decomposition products generated during the bleaching reaction.

4) Cold Rolling and Stacking Process: The cold rolling and stacking process is actually a one-bath process. When fabrics are pre-treated with the cold-rolling process, the scouring agent (caustic soda), bleach (hydrogen peroxide) and the corresponding additives are mixed together, and the fabric is pad-rolled and cold-rolled. Large rolls of rolls should be wrapped in plastic film to prevent air drying. Place 20 to 24 at room temperature for "chemical reaction (when the rolls are kept on top of the stack for slow rotation to prevent sputum), and then short steam and water wash. The process of cold-rolling and stacking bleaching is completed in the drying and drying process.The short steam after the cold pile and the sufficient hot water washing are very important for removing the decomposition products and are the key to guarantee the quality of the cold-rolling pile.

The appearance and popularity of cold-rolled reactor technology is the biggest highlight of the development of bleaching and lapping process in the past 30 years. The main chemical reaction of fabric cold-rolling during bleaching is carried out at room temperature. It is vividly stated that the cold-rolling practice bleaching is “cold bleaching”, which completely breaks through the traditional concept that scouring and hydrogen peroxide bleaching must be hot, and steam consumption. Only 507 of traditional craftsmanship. At the same time, only the consumption of chemicals used in cold-rolled construction bleaching is slightly lower than that of traditional bleaching and bleaching processes.