In the current printing and dyeing process, reactive dyes are one of the most widely used dyes. This is because reactive dyes are reactive dyes. The macromolecules of the dye contain reactive groups, which can react with the hydroxyl (-OH) or amino (-NH2) of the fiber during the dyeing process to form a covalent bond and fix it on the fiber. , So as to ensure that the dyed products have good fastness, and have the characteristics of bright color, complete chromatogram, safety and environmental protection, etc., and are widely used for dyeing and printing of cellulose fibers.
The traditional reactive dyes in the dyeing of cellulose fibers are generally composed of reactive dyes, dye promoters (usually sodium sulfate), and fixing alkali agents (usually soda ash). The dyeing process is generally: fabric pre-treatment → dyeing → washing → peracid neutralization → soaping → washing → post-treatment.
During the entire dyeing process, a large amount of sewage will be generated, and a large amount of sodium sulfate, fixing alkali and neutralizing acid will be consumed, which puts huge pressure on the environmental protection treatment of printing and dyeing enterprises; at the same time, due to the long time of traditional reactive dyeing process, a large amount of waste is consumed. The cost of water, electricity, gas, machinery and labor is too high, resulting in high overall dyeing costs. In recent years, the national environmental protection policy has become more and more stringent, and environmental protection governance has become more and more intense, which has severely restricted the development of printing and dyeing enterprises.
Features of alkali-free reactive dyes:
(1) The dyeing process does not need to add alkali-neutral dyeing, only need to add a small amount of sodium sulfate;
(2) No pickling or soaping is required after dyeing;
(3) Shorten the dyeing process time;
(4) Excellent compatibility and levelness, and extremely high lifting power;
(5) All indexes of dyeing products meet the salt-alkali requirements of traditional reactive dyes.