Compounds represented by the following Formula I:

##STR00001##

wherein:
R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are the same or different and are selected from the group consisting of SIL.sub.1-X, hydrogen, C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.5-C.sub.8 cycloalkyl, phenyl C.sub.1-C.sub.3 alkyl, and fluorine; X is optional, and if present is C.sub.1-C.sub.12 alkyl; SIL.sub.1 has the general formula:

(R.sup.7SiO.sub.3/2).sub.a(R.sup.7.sub.2SiO.sub.2/2).sub.b(R.sup.7.sub.3SiO.sub.1/2).sub.c wherein: R.sup.7 is selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.5-C.sub.8 cycloalkyl, alkoxyl, phenyl, and phenyl C.sub.1-C.sub.3 alkyl; a is a positive number, b is 0 or a positive number, c is 0 or a positive number, b/a is from 0 to 100, and c/a is from 0 to 10, wherein at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is SIL.sub.1-X; and
R.sup.6 is selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.5-C.sub.8 cycloalkyl, phenyl, phenyl C.sub.1-C.sub.3 alkyl, trimethylphenol, and fluorine,
a method to produce these compounds, and the use thereof as a photoinitiator.

The present invention relates to a series of novel multifunctional mono- and bis-acylphosphine oxides, which are useful as photoinitiators, and to photocurable compositions comprising said photoinitiators.

An acyl phosphine oxide initiator wherein the acyl group is selected from the group consisting of a benzoyl group substituted by an urea group or an oxalylamide group; a 2,6-dimethyl benzoyl group substituted in position 3 by an urea group or an oxalylamide group; a 2,6-dimethoxy benzoyl group substituted in position 3 by an urea group or an oxalylamide group; a 2,4,6-trimethyl benzoyl group substituted in position 3 by an urea group or an oxalylamide group; and a 2,4,6-trimethoxybenzoyl group substituted in position 3 by an urea group or an oxalylamide group.