PURPOSE: To decrease the yellowing of polyamide fiber with sunlight, etc., by applying a white ultraviolet absorber to a polyamide fiber, subjecting the fiber to fluorescent whitening treatment and sealing the amino terminal group of the polyamide fiber with an amino terminal sealing agent.
CONSTITUTION: A polyamide fiber is treated with a white ultraviolet absorber [preferably e.g. a combination of 2-ethoxy-2'-ethyloxalic acid bisanilide and 2-(3',5'-di-t-butyl-2'hydroxyphenyl-5-chlorobenzotriazole] and subjected to fluorescent whitening dyeing. The dyed fiber is uniformly impregnated with an amino terminal sealing agent (e.g. phthalic anhydride aliphatic carboxylic acid salt) to the core part of the fiber to uniformly seal the amino terminal group. Yellowing of the polyamide fiber caused by sunlight (ultraviolet ray), nitrogen oxide gas, vanillin, etc., can be decreased by this process.
KASHI TERUO
KIJIMA YOSHIAKI
Next Patent: TREATING AGENT FOR COLOR-PROCESSING OF INDIGO-DYED MATERIAL AND COLOR-PROCESSING METHOD