Sulfonated 2-(2'-hydroxyaryl)-2H-benzotriazoles and/or sulfonated aromatic formaldehyde condensates and their use to improve stain resistance and dye lightfasteness

A method for improving resistance to staining by anionic staining compounds and improving lightfastness of dyes on nylon material which comprises treating the material at a temperature between 30.degree. and 90.degree. C. with an aqueous solution of sulfonated 2-(2'-hydroxyaryl)-2H-benzotriazole having a structure represented by the formula ##STR25## wherein x is from 6 to 30 and M is selected from the group consisting of hydrogen, ammonium, aluminum, magnesium, lithium, sodium, and zinc.

A method for improving resistance to staining by anionic staining compounds and improving lightfastness of dyes on nylon fibers which comprises treating the fiber at a temperature between 30.degree. and 90.degree. C. with an aqueous solution of sulfonated 2-(2'hydroxyaryl)-2H-benzotriazole selected from the group consisting of ##STR26## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently the same or different C.sub.1 -C.sub.30 alkyl groups and Z.sub.1 and Z.sub.2 are each a C.sub.1 -C.sub.30 alkyl or sulfonated phenyl, naphthyl, phenanthryl or anthryl group, provided at least Z.sub.1 or Z.sub.2 is a sulfonated phenyl, naphthyl, phenanthryl or anthryl group.