Patent ID: 7407519

Claim:
A process for improving the sun protection factor (SPF) of cellulosic fibre materials and blends thereof, which comprises contacting said materials with at least one compound of the formula in which M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; R 1 and R 1 ′ independently of each other are —NH—R 3 , wherein R 3 is phenyl substituted by —CO—X—R 5 , wherein X is O or NH and R 5 is 2-hydroxyethyl, R 2 is a group of formula —O—R 4 wherein R 4 is alkoxy alkyl or hydroxy alkoxy alkyl, and R 2 ′ has the meaning of R 1 or R 2 and additionally contacting said materials with at least one UV absorber selected from the group consisting of o-hydroxybenzophenone, o-hydroxyphenylbenzotriazole, 2-aryl-2H-benzotriazole, salicylic acid ester, substituted acrylonitrile, substituted acrylaminoethylene, nitrilohydrazone, o-hydroxyaryl-1,3,5-triazine, sulphonated 1,3,5-triazine and oxalic anilide UV absorbers and where the SPF achieved is between 16.0 and 24.2.