A-aminoacetophenones as photoinitiators

A photocurable composition containing

• (A) at least one ethylenically unsaturated photopolymerizable compound,
• (B) at least one compound of the formula I ##STR123## in which Ar.sub.1 is an aromatic radical of the formula IV ##STR124## R.sub.5 is a group --N(R.sub.20)(R.sub.21) or --OR.sub.18, R.sub.1 is either (a) a radical of the formula ##STR125## or (b) a radical of the formula --CH(R.sub.13)Ar.sub.2, in which, if R.sub.5 is --OR.sub.18, Ar.sub.2 is a phenyl radical which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.8 alkylthio or --(OCH.sub.2 CH.sub.2).sub.n OCH.sub.3, or benzoyl, or in which, if R.sub.5 is --N(R.sub.20)(R.sub.21), Ar.sub.2 is a phenyl radical which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkoxy, or --(OCH.sub.2 CH.sub.2).sub.n OCH.sub.3, n being 1-10 R.sub.2, if R.sub.5 is --N(R.sub.20)(R.sub.21), has one of the meanings of R.sub.1 or is C.sub.1 -C.sub.8 alkyl, or,
• R.sub.2, if R.sub.5 is --OR.sub.18, is C.sub.1 -C.sub.18 alkyl or phenyl,
• R.sub.3 and R.sub.4 independently of one another are C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkyl, which is substituted by C.sub.1 -C.sub.4 alkoxy, --CN or --COO(C.sub.1 -C.sub.4 alkyl), or are allyl, cyclohexyl, or benzyl, or R.sub.3 and R.sub.4 together are C.sub.4 -C.sub.6 alkylene, which can be interrupted by --O-- or --N(R.sub.17)--,
• R.sub.6 is hydrogen, halogen, C.sub.1 -C.sub.4 alkyl, or has one of the meanings of R.sub.5,
• R.sub.7 and R.sub.8 are hydrogen or halogen,
• R.sub.9 is hydrogen or C.sub.1 -C.sub.4 alkyl,
• R.sub.13, R.sub.14, R.sub.15 and R.sub.16 independently of one another are hydrogen or methyl,
• R.sub.17 is hydrogen, C.sub.1 -C.sub.4 alkyl, benzyl, 2-hydroxyethyl or acetyl,
• R.sub.18 is hydrogen, C.sub.1 -C.sub.4 alkyl, benzyl, 2-hydroxyethyl, 2-methoxyethyl, 2-allyloxyethyl, allyl, cyclohexyl, phenyl, Si(CH.sub.3).sub.3 or C.sub.1 -C.sub.6 alkyl, which is substituted by --COO(C.sub.1 -C.sub.4 alkyl),
• R.sub.20 and R.sub.21 independently of one another are hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.6 alkoxyalkyl, acetyl, allyl or benzyl, or R.sub.20 and R.sub.21 together are C.sub.4 -C.sub.6 alkylene, which can be interrupted by --O-- or --N(R.sub.17)--,
• in the case where R.sub.1 is allyl and R.sub.2 is methyl, R.sub.5 is not --OCH.sub.3, and in the case where R.sub.1 is benzyl and R.sub.2 is methyl or benzyl, R.sub.5 is not OCH.sub.3.