Oxime ester photoinitiators

1. A photopolymerizable composition comprising,

(a) at least one ethylenically unsaturated photopolymerizable compound and

(b) at least one compound of formula I

wherein

Q is a direct bond or phenylene;

n is an integer 2; wherein the multiple radicals R 1 , R 2 , Y and Z in the compound of formula I are identical or different;

Z is C 1 -C 6 -alkylene;

Y is phenyl which is substituted by C 1 -C 4 -alkyl or OR 6 ;

R 1 is C 1 -C 4 -alkyl;

R 2 is C 1 -C 4 -alkyl;

R 6 is C 1 -C 4 -alkyl;

and

(c) at least one colorant selected from the group consisting of pigments and dyes.

2. The photopolymerizable composition according to claim 1 , comprising as component

(c) at least one colorant selected from the group consisting of black pigments and black dyes.

3. The photopolymerizable composition according to claim 1 , wherein the component (a) is a resin obtained by the reaction of a saturated or unsaturated polybasic acid anhydride with a product of the reaction of an epoxy resin and an unsaturated monocarboxylic acid.

4. The photopolymerizable composition according to claim 1 , wherein additionally to the photoinitiator (b) comprising at least one further component selected from the group consisting of photoinitiator (d) and other additives (e).

5. The photopolymerizable composition according to claim 4 wherein further additive (e) comprises a dispersant or a mixture of dispersants.

6. The photopolymerizable composition according to claim 4 , comprising 0.05 to 25% by weight of the photoinitiator (b), or the photoinitiators (b) and (d), based on the composition.

7. The photopolymerizable composition according to claim 4 , wherein as further additive (e) comprising a photo sensitizer selected from the group consisting of benzophenone and its derivatives, thioxanthone and its derivatives, anthraquinone and its derivatives and coumarin and its derivatives.

8. The photopolymerizable composition according to claim 1 , wherein component (c) comprises a pigment or a mixture of pigments or dyes or a mixture of dyes or a mixture of one or more pigments with one or more dyes.

9. The photopolymerizable composition according to claim 1 which further comprises a binder polymer (f).

10. A process for the photopolymerization of compounds containing ethylenically unsaturated double bonds, which comprises irradiating the photopolymerizable composition according to claim 1 with electromagnetic radiation in the range from 150 to 600 nm, or with electron beam or with X-rays.

11. A process according to claim 10 , for producing paints, powder coatings, printing inks, printing plates, adhesives, dental compositions, gel coats, photoresists for electronics, for encapsulating electrical and electronic components, for producing magnetic recording materials, micromechanical parts, waveguides, optical switches, plating masks, colour proofing systems, glass fibre cable coatings, screen printing stencils, three-dimensional objects by means of stereolithography, microelectronic circuits, decolorizing materials or formulations containing microcapsules.

12. A color filter prepared by providing red, green and blue picture elements and optionally a black matrix, all comprising a photosensitive resin and a pigment on a transparent substrate and providing a transparent electrode either on the surface of the substrate or on the surface of the color filter layer, wherein said photosensitive resin is the photopolymerizable composition according to claim 1 .

13. A coated substrate which is coated on at least one surface with the photopolymerizable composition according to claim 1 .

14. A process for the photographic production of relief images, in which a coated substrate according to claim 13 is subjected to image-wise exposure and then the unexposed portions are removed with a developer.

15. A process for the preparation of a compound of the formula I

wherein

n is an integer 2; wherein the multiple radicals R 1 , R 2 , Y and Z in the compound of formula I are identical or different;

R 1 is C 1 -C 4 -alkyl;

which comprises reacting the corresponding oxime compound of formula IA,

wherein

wherein

Q is a direct bond or phenylene;

n is an integer 2; wherein the multiple radicals, R 2 , Y and Z in the compound of formula IA are identical or different;

Z is C 1 -C 6 -alkylene;

Y is phenyl which is substituted by C 1 -C 4 -alkyl or OR 6 ;

R 2 is C 1 -C 4 -alkyl;

R 6 is C 1 -C 4 -alkyl;

R 15 , R 16 , R 17 , R 18 , R 19 and R 20 are hydrogen;

with an acyl halide of the formula II or an anhydride of the formula III

wherein Hal is a halogen, and R 1 is as defined above,

in the presence of a base or a mixture of bases.

16. The process as claimed in claim 15 , wherein Hal is Cl.

17. A free oxime compound of the (IA)

wherein

Q is a direct bond or phenylene;

n is an integer 2; wherein the multiple radicals R 2 , Y and Z in the compound of formula IA are identical or different;

Z is C 1 -C 6 -alkylene;

Y is phenyl which is substituted by C 1 -C 4 -alkyl or OR 6 ;

R 2 is C 1 -C 4 -alkyl;

R 15 , R 16 , R 17 , R 18 , R 19 and R 20 are hydrogen.

18. A photopolymerizable composition comprising,

(a) at least one ethylenically unsaturated photopolymerizable compound and

(b) at least one compound of formula I

wherein

Q phenylene;

n is an integer 2; wherein the multiple radicals R 1 , R 2 , Y and Z in the compound of formula I are identical or different;

Z is C 1 -C 6 -alkylene;

Y is phenyl which is substituted by C 1 -C 4 -alkyl or OR 6 or

Y is C 3 -C 5 -heteroaryl;

R 1 is C 1 -C 4 -alkyl;

R 2 is C 1 -C 4 -alkyl;

R 6 is C 1 -C 4 -alkyl;

and

(c) at least one colorant selected from the group consisting of pigments and dyes.