What effect does the choice of leveling agent have on nylon dyeing?

Weak acid dyes have less water-soluble groups than strong acid dyes, have a higher affinity for nylon fibers, and have poorer solubility in aqueous solution than strong acid dyes. The dyeability and levelness are poor.

In the process of fiber spinning and weaving of nylon and its elastic fabrics, the physical and chemical structures of the fibers themselves are not uniform, including differences in fineness, internal stress, molecular structure orientation, etc., or differences in fiber chemical properties, such as fiber ends. The difference in the number of amino groups will also cause dyeing problems such as the formation of color bars and rungs during the dyeing process. In addition, operational problems in the dyeing process will affect the levelness of nylon dyeing. Therefore, the selection of a good leveling agent can effectively prevent or reduce the occurrence of the above problems.

There are many kinds of leveling agents for nylon dyeing, including fiber-friendly anionic type, dye-friendly polymer type, and amphiphilic zwitterionic type. The zwitterionic leveling agent has a large molecular weight, has excellent leveling effect on weakly acidic dyes with a large molecular weight, has a high dye migration ability, and has the ability to level the dyeing rate of different types of acid dyes.