Photosensitive resin composition

1. A photosensitive composition comprising,

(A) an oligomer or polymer containing at least one carboxylic acid group in the molecule and having a molecular weight of 200,000 or less selected from the group consisting of copolymers of (meth)acrylic acid with ethylenically unsaturated compounds,

(B) at least one photoinitiator compound of formula I

R 1 is linear or branched C 1 -C 12 alkyl;

R 2 is linear or branched C 1 -C 4 alkyl;

R 3 and R 4 independently of one another are linear or branched C 1 -C 8 alkyl; and

(C) an ester of a polyol, wherein the polyol is partially or fully esterified with an ethylenically unsaturated carboxylic acid.

2. A photosensitive composition according to claim 1 , wherein

R 1 is linear or branched C 1 -C 4 alkyl,

R 2 is methyl, ethyl or propyl and

R 3 and R 4 independently of one another are linear or branched C 1 -C 4 alkyl.

3. A photosensitive composition according to claim 1 , wherein the compound of formula I is

1-[4-morpholinophenyl]-2-dimethylamino-2-(4-methylbenzyl)-butane-1-one,

1-[4-morpholinophenyl]-2-dimethylamino-2-(4-ethylbenzyl)-butane-1-one,

1-[4-morpholinophenyl]-2-dimethylamino-2-(4-isopropylbenzyl)-butane-1-one,

1-[4-morpholinophenyl]-2-dimethylamino-2-(4-n-propylbenzyl)-butane-1-one,

1-[4-morpholinophenyl]-2-dimethylamino-2-[4-(2-methylprop-1-yl)-benzyl]-butane-1-one, or

1-[4-morpholinophenyl]-2-dimethylamino-2-(4-n-butylbenzyl)-butane-1-one.

4. A photosensitive composition according to claim 1 , wherein component (A) has a molecular weight of 2,000-150,000.

5. A photosensitive composition according to claim 1 , comprising in addition to the components (A), (B) and (C), at least one benzophenone, thioxanthone, anthraquinone or coumarin photosensitizer compound (E).

6. A photosensitive composition according to claim 1 , comprising in addition to the components (A), (B) and (C), at least one compound having epoxy groups as thermosetting component (F) and one epoxy curing promoter (G2).

7. A photosensitive composition according to claim 1 , comprising in addition to the components (A), (B) and (C), at least one ultraviolet-absorber or light stabilizer compound (G3).

8. A photosensitive composition according to claim 1 , comprising further additives (G), which are selected from the group consisting of colorants, dispersants, thermal polymerization inhibitors, thickeners, antifoaming agents, leveling agents and inorganic fillers.

9. A photosensitive composition according to claim 1 , comprising 0.015 to 100 parts by weight, based on 100 parts by weight of component (A), of the photoinitiator (B).

10. A photosensitive composition according to claim 1 , wherein component (A) is a coplymer comprising as monomers acrylic or methacrylic acid and one or more monomers selected from esters of methacrylic, acrylic, maleic and fumaric acid.

11. A photosensitive composition according to claim 1 , wherein component (C) comprises an acrylate or methacrylate ester of a polyol selected from the group consisting of aliphatic and cycloaliphatic alkylenediols having 2 to 12 carbon atoms, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, hydroquinone, 4,4′-dihydroxydiphenyl and 2,2-di(4-hydroxyphenyl)propane.

12. A photopolymerization process which comprises irradiating a composition according to claim 1 with electromagnetic radiation in the range from 190 to 600 nm, or with electron beam or with X-rays.

13. A process according to claim 12 for producing pigmented and non-pigmented paints or varnishes, powder coatings, optical fiber coatings, printing inks, printing plates, adhesives, dental compositions, photoresists for electronics, electroplating resist, etch resist, solder resist, resists for color filters, structures of plasma-display panels, electroluminescence displays, liquid crystal displays, composite compositions, color filter materials, encapsulated electrical or electronic components, magnetic recording materials, micromechanical parts, waveguides, optical switches, plating masks, etch masks, colour proofing systems, glass fibre cable coatings, screen printing stencils, three-dimensional objects prepared by means of microlithography, plating, stereolithography, image recording materials, holographic recordings, microelectronic circuits, decolorizing materials, dielectric layers in a sequential build-up layer of a printed circuit board or a process using ultraviolet and visible laser as a light source of a direct imaging technique.

14. A coated substrate which is coated on at least one surface with a composition according to claim 1 .