Multifunctional acylphosphine oxide photoinitiators

1. Photoinitiators of formula I:

wherein:

each said A represents independently of one another O, S, or NR 3 ;

said G is a residue of multifunctional compound G-(A-H) m+n , wherein each said A-H represents an alcohol, amino or thiol group;

said m and said n are both integer numbers and m+n has a value in the range of 3 to 10;

said m has a value ranging from 3 to 8;

each said R 1 represents, independently of one another, C 1 -C 18 alkyl, C 6 -C 12 aryl or C 5 -C 12 cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or is a five- to six-membered heterocyclic radical containing oxygen and/or nitrogen and/or sulfur atoms, wherein said radical may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

each said R 2 represents, independently of one another R 1 —(C═O)—, C 1 -C 18 alkyl, C 6 -C 12 aryl or C 5 -C 12 cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or is a five- to six-membered heterocyclic radical containing oxygen and/or nitrogen and/or sulfur atoms, where said radical may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

said Y is O or S; and

said R 3 is hydrogen or C 1 -C 4 alkyl;

provided that the photoinitiators of formula I do not contain photocurable ethylenically unsaturated groups.

2. The photoinitiators of claim 1 , wherein said m+n has a value within a range of 3 to 8.

3. The photoinitiators of claim 1 , wherein said m has a value within a range of 3 to 6.

4. The photoinitiators of claim 1 , wherein said R 1 is selected from the group consisting of phenyl, 2,6-dichlorophenyl, 2,4,6-trichlorophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-dimethoxyphenyl, 2,6-diethoxyphenyl, α-naphthyl, 2,6-dinitrophenyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, tert-butyl, pentyl, hexyl, heptyl, octyl and 2-ethylhexyl.

5. The photoinitiators of claim 1 , wherein said R 2 is selected from the group consisting of R 1 —(C═O)—, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, 2-ethylhexyl, phenyl, xylyl, 4-biphenylyl, 2-, 3- or 4-chlorophenyl, 2,4-dichlorophenyl, 2-, 3- or 4-methylphenyl, 2,4-dimethylphenyl, 2-, 3- or 4-ethylphenyl, 2-, 3- or 4-methoxyphenyl, 2,4-dimethoxyphenyl, 2-, 3- or 4-ethoxyphenyl, α-naphthyl, methylnaphthyl, chloronaphthyl, ethoxynaphthyl and 2- or 4-nitrophenyl.

6. The photoinitiators of claim 1 , wherein said G-(A-H) m+n is selected from the group consisting of monomeric polyols, oligomeric polyols, polymeric polyol and a mixture thereof.

7. A photocurable composition comprising:

a) from 0.05 to 20% by weight of at least one photoinitiator of formula I;

wherein said A, G, m, n, R 1 , R 2 , Y and R 3 do not contain photocurable ethylenically unsaturated groups;

each said A represents independently of one another O, S, or NR 3 ;

said G is a residue of multifunctional compound G-(A-H) m+n , wherein each said A-H represents an alcohol, amino or thiol group;

said m and said n are both integer numbers and m+n has a value in the range of 3 to 10;

said m has a value ranging from 3 to 8;

each said R 1 represents, independently of one another, C 1 -C 18 alkyl, C 6 -C 12 aryl and C 5 -C 12 cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered heterocyclic radical containing oxygen and/or nitrogen and/or sulfur atoms, wherein said radical may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

each said R 2 represents, independently of one another R 1 —(C═O)—, or one of C 1 -C 18 alkyl, C 6 -C 12 aryl and C 5 -C 12 cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or is a five- to six-membered heterocyclic radical containing oxygen and/or nitrogen and/or sulfur atoms, where said radical may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

said Y is O or S; and

said R 3 is hydrogen or C 1 -C 4 alkyl; and

b) from 30 to 99.9% by weight of at least one ethylenically unsaturated compound.

8. The photocurable composition of claim 7 , wherein said photocurable composition comprises from 0.2 to 10% by weight of said at least of said photoinitiator of formula I and from 50 to 98.9 by weight of said at least one ethylenically unsaturated compound.

9. The photocurable composition of claim 7 , further comprising c) from 0.5 to 15% by weight of a further photoinitiator.

10. The photocurable composition of claim 7 , further comprising c) from 0.05 to 12% by weight of a photosensitizer.

11. Photoinitiators of formula I:

wherein:

each said A represents independently of one another O, S, or NR 3 ;

said G is a residue of multifunctional compound G-(A-H) m+n , wherein each said A-H represents an alcohol, amino or thiol group;

said m and said n are both integer numbers and m+n has a value in the range of 3 to 10;

said m has a value ranging from 3 to 8;

each said R 1 represents, independently of one another, C 1 -C 18 alkyl, C 6 -C 12 aryl or C 5 -C 12 cycloalkyl, which may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

each said R 2 represents, independently of one another R 1 —(C═O)—, C 1 -C 18 alkyl, C 6 -C 12 aryl or C 5 -C 12 cycloalkyl, which may be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals;

said Y is O or S; and

said R 3 is hydrogen or C 1 -C 4 alkyl;

wherein the photoinitiators of formula I do not contain photocurable ethylenically unsaturated groups.