| abstract |
Compounds of the formula I, II, III and IIIa <IMAGE> I <IMAGE> II <IMAGE> III <IMAGE> IIIa in which Ar1 is an unsubstituted or substituted aromatic radical and at least one of the radicals R1 and R2 is an alkenyl, cycloalkenyl or arylmethyl group, are effective photoinitiators for photopolymerization of unsaturated compounds. They are particularly suitable for photocuring of pigmented systems. |