Process for improving the sun protection factor of cellulosic fibre material

1 1332 33 55 142 4 4 21 2A 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) in which M is hydrogen, an alkali metal atom, ammonium or a cation formed from an amine; Rand R′ independently of each other are -NH-R, -N(R)or -O-R, wherein Ris aryl substituted by -CO-X-R, wherein X is O or NH and Ris optionally substituted C-C-alkyl, Ris a group of formula -O-Rwherein Ris hydroxy alkyl, alkoxy alkyl or hydroxy alkoxy alkyl, and R′ has the meaning of Ror R.