1 Choose the right dye
The color fastness is closely related to the structure of the dye, and the selection of the dye should consider:
① Strong reactivity between dyes and fibers;
②High fixation rate;
③It has better acid-base stability;
④ The bond energy of the covalent bond of the dye-fiber is high, the chemical stability is better, and the bond is not easy to break;
⑤ The ability of antioxidants and reducing agents is better;
⑥ The compatibility and compatibility of color matching dyes are better.
2 Choose the right dyeing process
The dyeing process has a great influence on the color fastness. The selection of the dyeing process can be considered from the following aspects:
a. ① Try to use higher temperature dyeing, such as using medium temperature dye (KN type) dyeing, the dyeing temperature can be increased from 60~65℃ to 75~80℃, and then reduced to 60~65℃, and then add alkali to fix the color;
②Using low temperature weak alkali to fix color;
③The fixing temperature is generally 60~65℃;
④The fixing agent adopts a single soda ash;
⑤ pH is stable at around 11;
⑥ Soda ash is added in stages;
⑦ Use the correct water washing and soaping process. The purpose of soaping is to remove floating color, and the purpose of water washing is to remove the residual alkali agent on the fiber. Washing and soaping should prevent the bonded dyes from breaking, hydrolyzing, and falling off the fibers.
To this end, pay attention to the following points: wash with water before soaping, choose a soaping agent with good washing ability, dispersing ability, emulsifying ability and dirt-carrying ability, must be at a higher temperature (90 ℃) under neutral conditions Soap.
b. For the special reactive green blue dyes, the hydrolysis is accelerated under the condition of salt. R blue blue has high directness and is very sensitive to alkali. A special dyeing process is given for these two special dyes, which is different from the conventional KN type dyes. , for the special Cuilan and Yanlan, different dyeing heating curves and the process of adding saline and alkali are introduced to avoid the generation of colored flowers and to improve the reproducibility.