| abstract |
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 (1) n nin 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 , —N(R 3 ) 2 or —O—R 3 , wherein R 3 is aryl substituted by —CO—X—R 5 , wherein X is O or NH and R 5 is optionally substituted C 1 -C 4 -alkyl, R 2 is a group of formula —O—R 4 wherein R 4 is hydroxy alkyl, alkoxy alkyl or hydroxy alkoxy alkyl,n nand R 2 ′ has the meaning of R 1 or R 2 . |