Investigations on the migration properties of acid dyes in the dyeing of polyamide microfibre

Abstract Retarding the uptake rate of dyes and enhancing the migration ability of dyes are two basic measures to be taken to improve the dyeing levelness of polyamide microfibre. In this work, the migration properties of acid dyes during the dyeing of polyamide microfibre were discussed. The effects of the category and molecular mass of dyes, and the conditions of dyeing (pH, temperature, dye concentration, and auxiliaries) on dye migration were evaluated, and the ability of dye migration on polyamide microfibre, wool, and silk was compared. Acid dyes had lower migration ability on polyamide microfibre than on wool and silk. The migration ability of different varieties of dyes displayed great differences, and decreased in the following order: acid levelling dyes > acid half‐milling/milling dyes > 1:2 metal complex dyes. The migration percentage of acid dyes increased with increasing pH, temperature and dye concentration. Various types of surfactants displayed different degrees of ability in enhancing the migration of acid half‐milling/milling dyes. Fatty amine polyoxyethylene ether (weakly cationic) had the strongest promoting effect on the migration of dyes, followed by sodium alcohol ether sulphate (anionic) and fatty alcohol polyoxyethylene ether (nonionic), while amphoteric surfactants displayed a minor promoting effect. Notably, in the migration test, the migration percentage of dyes was significantly linearly correlated with the extent of dye desorption from fibres.