7. Environmentally-friendly cationic dyes
Cationic dyes are special dyes for polyacrylonitrile fibers. Cationic dyes usually use zinc chloride to precipitate complex salts during the manufacturing process. The commercial zinc content is high, generally 15% to 20%. ETAD clearly stipulates that zinc is one of the heavy metals that need to be controlled in dyes. Therefore, the development of environmental-friendly cationic dyes is mainly a problem of zinc in dyes. Through technological transformation, the new manufacturing technology no longer uses zinc chloride, but instead uses other environmentally and ecologically harmless precipitants. The resulting cationic dyes meet the requirements of environmentally friendly dyes, such as Viocryl Red GRLS from D&G Dyes in the United Kingdom. ZF 200%, Viocryl Navy FBL ZF, Viocryl Black FL ZF 2 00% and the like are all zinc-free cationic dyes.
Problems with environmentally friendly dyes There is currently a misconception among many manufacturers, especially dye users, that azo dyes are both non-environmental dyes. This is not actually the case. Instead, azo dyes containing 22 dye intermediates that are carcinogenic or cleave carcinogenic substances are non-environmental dyes.