Mono- and di-acylphosphine oxides

摘要

Compounds of the formula I <IMAGE> I in which at least one of the radicals R1, R2 and R3 is a substituted alkyl radical or cycloalkyl radical, or R1 and R2 together with the phosphorus atom form a monocyclic or tricyclic ring, are effective photoinitiators for the photopolymerization of ethylenically unsaturated compounds.