Fixing agent for improving fastness properties of dyeings on polyamide fibers and preparation thereof

摘要

A fixing agent for improving the fastness properties of dyeings on polyamide fibers being a new condensation product of 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfonesulfonic acid and a lower aliphatic aldehyde, which has a mean molecular weight of about 5,000 to about 30,000 and a ratio of carbon atom content and sulfur atom content of 3.0:1 to 4.8:1, or its metal salt, and when polyamide fibers are treated with the condensation product or its metal salt, or the condensation product in the presence of a salt of metal, at a temperature of 95 DEG to 120 DEG C., the fastness properties, especially wet-fastness properties of dyeings on polyamide fibers are remarkably improved.