Dyed antistain nylon with cationic dye modifier

摘要

Shaped articles, such as fibers, formed of a polyamide formed by salt- blending the polyamide precursor salt with a cationic dye modifier, such as the dimethyl ester of 5-sulfoisophthalic acid, followed by polymerization, are rendered resistant to staining by acid dyes at ambient conditions either by adding an acid dye to the polymer melt or by dyeing with an acid dye from an acid dyebath at pH 2 to 7 and 60° to 100° C. so that the shaped article contains from at least 0. 0048 and preferably at least 0.0096 wt % of an acid dyestuff. In a preferred aspect of the invention, the shaped articles are oriented, crimped, heat- set fibers for use as the facing in carpets.