Method for dyeing fibrous materials and dye assistant relating to the same

摘要

A method for dyeing fibrous material is provided. The method includes contacting a fibrous material with a dyebath comprising a mixture of a dye assistant and a dye soluble or dispersed with the dye assistant in the dyebath. The dye assistant comprises a N-alkyl substituted aromatic sulfonamide. The dye assistant of the present invention can be advantageously utilized for dyeing difficult to dye fibers such as aromatic polyamide fibers, polybenzimidazole fibers and aromatic polyimide fibers.