Views: 0 Author: Site Editor Publish Time: 2021-09-25 Origin: Site
Fixing agent is a non-formaldehyde base dye fixing agent for direct and reactive dyes, with excellent light resistance, chlorine resistance, etc. It prevents dye bleeding during the washing process.
This passage is going to talk about the followings of fixing agent:
(1) Why using fixing agent - problems and solutions?
(2) What is fixing agent used for?
(3) Precautions for storage and handling of fixing agent
Reactive dyes always have some defects. The utilization rate is not high enough, generally 60% to 70%, and a large amount of colored sewage is produced, the chroma of which is more than several thousand times, the COD value is generally 8,000 to 30,000 ppm, and the COD value of concentrated wastewater exceeds 50,000 ppm. In order to suppress the charge on the fiber surface, the reactive dyes need to consume a considerable amount of electrolyte when using, which not only increases labor intensity, but also causes the chloride ion concentration in the wastewater to reach more than 100,000 ppm, which greatly increases the difficulty of treating reactive dye wastewater. .
Certain color fastnesses cannot meet market requirements, such as light fastness to perspiration, wet rubbing fastness, and light fastness of azo red dyes and azo blue dyes in light colors. There are fewer dark varieties that can replace vulcanizates and vat dyes.
At present, the way to solve the technical problems of reactive dyes is mainly to increase the absorption rate and fixation rate. The most effective method is to introduce two different or the same active groups into the reactive dye molecule, especially the former is to introduce two active groups. ―Chlorine triazinyl and vinyl sulfone group.
For the new reactive dyes composed of these two heterogeneous reactive groups and suitable parent dyes and linking groups, in addition to the characteristics of each constituent reactive group, low alkaline hydrolysis rate, high acidic hydrolysis and bond breaking stability, excellent In addition to its washability, good various fastnesses and a small difference between the absorption rate and the fixation rate, it also has new characteristics generated by the addition and interaction between two different active groups, and better acid resistance Hydrolysis and peroxide washing ability, higher fixation rate, wider dyeing temperature range, better dyeing reproducibility and suitable for medium temperature dyeing, low temperature dyeing, short-term dyeing, high first-time success rate (RFT), etc. Therefore, the output of such reactive dyes has accounted for two-thirds of all dyeing dyes, and has become the main dye for pad dyeing and dip dyeing of cotton fabrics.
Reactive dyes are composed of parent dyes, linking groups and active groups, so that they can form a firm covalent bond with fibers during use. When dyeing, the dye can be dyed directly on the cloth. At the same time, because of its good diffusion ability, it is easy to diffuse the dye into the fiber, but because it has not chemically reacted with the fiber at this time, it is easy to wash most of the dye with water. Therefore, an alkaline agent must be used to promote a chemical reaction between the dye and the fiber to fix the dye on the fiber. The former is called dyeing and the latter is called fixation. Fixing agent is used at this stage.
Fixing agent should be stored in a cool place and avoid storing in direct sunlight. Should be stored at room temperature and ambient temperature. If the temperature is too high or too low, it may fail. Fixing agents are chemicals, and you should follow the usual precautions to keep them away from your eyes and skin. Keep out of children's reach.
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