Mercaptophenyl ketones as initiators for the photopolymerization of

Abstract

Mixtures of (A) a mercaptophenyl ketone of the formula I ##STR1## in which n is 1 or 2, Ar is an unsubstituted or substituted aryl radical or a hetero-aromatic radical, R.sup.1 is hydrogen, alkyl or, if n is 1, also --SCH.sub.2 X and X, if n is 1, is one of the groups --CH(R.sup.2)--OH, --CH(R.sup.2)--O--CO--R.sup.5, --CH.sub.2 SH or --(CH.sub.2).sub.1-3 --NR.sup.3 R.sup.4, in which R.sup.2 is hydrogen, methyl, phenyl or one of the groups --CH.sub.2 OH, --CH.sub.2 --NR.sup.3 R.sup.4 or --CH.sub.2 --OR.sup.6, R.sup.3 and R.sup.4 independently of one another are hydrogen, alkyl or hydroxyalkyl, or R.sup.3 and R.sup.4 together are 1,4-butylene, 1,5-pentylene or 3-oxa-1,5-pentylene, and R.sup.5 and R.sup.6 are monovalent hydrocarbon radicals, and X, if n is 2, is alkylene, vinylene, phenylene or one of the divalent groups --CH.sub.2 S--SCH.sub.2 --, --CH(R.sup.2)--O--CO--O--CH(R.sup.2)--, --CH(R.sup.2)--O--CO--R.sup.7 --CO-- OCH(R.sup.2)--, --CO--O--R.sup.8 --O--CO--, --CH.sub.2 COO--R.sup.8 --OOCCH.sub.2 -- or --CH(OH)--CH.sub.2 --O--R.sup.8 --O--CH.sub.2 --CH(OH)--, in which R.sup.7 is a divalent hydrocarbon radical or --NH--R.sup.9 --NH--and R.sup.8 and R.sup.9 are divalent hydrocarbon radicals, and (B) an organic amine are effective initiators for the photopolymerization of ethylenically unsaturated compounds or for the photochemical crosslinking of polyolefins.