Process for preventing yellowing of polyamide fibre materials treated with stain-blocking agents by treatment with water-soluble light stabilizer having fibre affinity

DETAILED DESCRIPTION We claim: 1.
A process for preventing yellowing of a polyamide fiber material treated with a stain-blocking agent, which comprises treating the polyamide fiber material with a water-soluble light stabilizer with affinity for the fiber which is of the formula ##STR21## in which R is a radical of the formula ##STR22## in which Q is hydrogen or halogen, Q.
sub.
1 is hydrogen, halogen, C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, C.
sub.
2 -C.
sub.
9 alkoxycarbonyl, carboxyl or sulfo, Q.
sub.
2 and Q.
sub.
3 independently of one another are C.
sub.
3 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, C.
sub.
5 -C.
sub.
6 cycloalkyl, phenyl or phenyl which is substituted by C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, C.
sub.
2 -C.
sub.
5 alkanoyloxy, C.
sub.
1 -C.
sub.
4 alkylcarbamoyloxy or hydroxy, Q.
sub.
4 is phenyl or phenyl which is substituted by C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, sulfo, halogen or hydroxy and Q.
sub.
5 is C.
sub.
1 -C.
sub.
4 alkyl, phenyl or phenyl which is substituted by C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, halogen or hydroxy, and the benzen ring A corresponds to the following radicals ##STR23## in which R.
sub.
1 is hydrogen, C.
sub.
1 -C.
sub.
4 alkyl, chlorine, C.
sub.
5 -C.
sub.
6 cycloalkyl, C.
sub.
7 -C.
sub.
9 -phenylalkyl, sulfo or sulfo-C.
sub.
7 -C.
sub.
9 phenylalkyl, R.
sub.
2 is hydrogen, hydroxyl, C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, chlorine or sulfo and R.
sub.
3 is C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
3 -C.
sub.
4 -alkoxy, hydroxy, phenyl, (C.
sub.
1 -C.
sub.
8 alkyl)-phenyl, C.
sub.
5 -C.
sub.
6 cycloalkyl, C.
sub.
2 -C.
sub.
9 -alkoxycarbonyl, chlorine, carboxyethyl, C.
sub.
7 -C.
sub.
9 phenylalkyl, sulfo or sulfo-C.
sub.
7 -C.
sub.
9 phenylalkyl, if R is a radical of the formula (II); ##STR24## in which R.
sub.
4 is hydrogen, halogen, C.
sub.
1 -C.
sub.
4 alkyl or sulfo, R.
sub.
5 is hydrogen, C.
sub.
1 -C.
sub.
4 alkyl, C.
sub.
1 -C.
sub.
4 alkoxy, C.
sub.
2 -C.
sub.
5 alkanoyloxy, C.
sub.
1 -C.
sub.
4 alkylcarbomoyloxy or hydroxy and M is hydrogen or an alkali metal, if R is radical of the formula (III), and ##STR25## in which R