Heat-curable resin composition

1. A resin composition comprising:

(i) an at least bifunctional prepolymer (A) curable under the action of heat selected from the group consisting of an epoxy compound having more than one epoxide group per molecule, an acrylate resin, a polyurethane resin, a cyanate ester resin, a benzoxazine resin, a polyphenylene resin, a polyimide resin and mixtures thereof;

(ii) a telechelic elastomer;

(iii) a particulate material having an elastomeric core and a thermoplastic shell; and

(iv) a photocurable prepolymer (B) selected from the group consisting of: a photocurable prepolymer having an acid value of from 40 to 250 mg KOH/g obtained by the reaction of an unsaturated monobasic acid copolymer resin with a compound which contains an alicyclic epoxy group; a photocurable prepolymer obtained by complete esterification of epoxy groups of an epoxy resin with an α,β-unsaturated carboxylic acid with formation of a first product and subsequent reaction of the first product thus obtained with a saturated or an unsaturated polybasic acid anhydride; a photocurable prepolymer obtained by the reaction of a bisphenol A epoxy resin with epichlorohydrin with formation of a postglycidylated epoxy resin, subsequent complete esterification of the epoxy groups of the postglycidylated epoxy resin with an α,β-unsaturated carboxylic acid with formation of a second product and subsequent reaction of the second product thus obtained with a saturated or an unsaturated polybasic anhydride; and a photocurable prepolymer obtained by the reaction of a bisphenol A epoxy resin with epichlorohydrin with formation of a postglycidylated epoxy resin, mixing of the postglycidylated epoxy resin with a novolak epoxy resin, complete esterification of the mixture with an α,β-unsaturated carboxylic acid with formation of a third product and subsequent reaction of the third product thus obtained with a saturated or unsaturated polybasic acid anhydride.

2. A resin composition according to claim 1 , which additionally comprises a photopolymerization initiator.

3. A resin composition according to claim 1 , which additionally comprises an epoxide curing agent.

4. A resin composition according to claim 1 , which additionally comprises fillers.

5. A resin composition according to claim 1 , in which the prepolymer (A) curable by the action of heat is an epoxy compound having more than one epoxide group per molecule.

6. A resin composition according to claim 1 , in which the telechelic elastomer contains a hetero atom.

7. A resin composition according to claim 1 , in which the telechelic elastomer has the formula I

in which g is a number from 1 to 20 and h a number from 1 to 400.

8. A resin composition according to claim 1 , in which the particulate material has a core comprising a silicone resin and shell comprising an acrylate resin.

9. A resin composition according to claim 1 , in which the weight ratio of (ii) the telechelic elastomer to (iii) the particulate material is from 1:5 to 5:1.

10. A resin composition according to claim 1 , in which the photocurable prepolymer (B) is a compound of the formula

in which

R 1 is hydrogen or a methyl group;

R 2 is a divalent aliphatic saturated hydrocarbon group having 1-14 carbon atoms,

R 10 , R 11 and R 12 , independently of one another, are hydrogen or a methyl group,

Z is a direct bond or a divalent cycloalkane having 5 to 10 carbon atoms,

a is a number from 1 to 10, and

b and c are, independently numbers from 0 to 10.

11. A resin composition according to claim 1 , additionally comprising a compound of the formula (III)

in which A is a mono- to tetravalent, saturated or unsaturated alkyl group having 1 to 60 carbon atoms or aryl group, a dialkylamino group (q =0) or a bivalent monoalkylamino group (q =1) having 1 to 4 carbon atoms, carboxyalkylene groups or alkoxycarbonylalkylene groups having 1 to 4 carbon atoms,

n is 1 or 2, m is 2−n and q is a number from 0 to 3,

X is a radical of the formula

in which R 3 and R 4 are identical or different and each radical, independently of one another, is hydrogen, a straight-chain or branched alkyl group or hydroxyalkyl group having 1 to 5 carbon atoms, or R 3 and R 4 together may form an aliphatic ring and

R 5 is hydrogen or an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 1 to 5 carbon atoms.

12. A resin composition according to claim 1 , further comprising a compound of the formula (IV)

in which R 4 is hydrogen or a methyl group.

13. A printed circuit comprising a layer produced by curing a resin composition according to claim 1 .

14. A printed circuit according to claim 13 in the form of a circuit board.

15. A packaging unit comprising two containers A and B, wherein container A comprises an at least bifunctional prepolymer (A) curable by the action of heat selected from the group consisting of an epoxy compound having more than one epoxide group per molecule, an acrylate resin, a polyurethane resin, a cyanate ester resin, a benzoxazine resin, a polyphenylene resin, a polyimide resin and mixtures thereof and container B comprises the remaining ingredients of the resin composition of claim 1 .

16. A process for the production of a circuit board comprising the steps of forming a layer of the composition of claim 1 on the circuit board and curing the layer.

17. The process of claim 16 , further comprising after formation of the layer, the step of drying the layer.

18. The process of claim 17 , wherein the drying step is carried out at 60 to 90° C. and from 15 to 60 minutes.

19. The process of claim 16 , in which, before the curing step, a photopolymerization is carried out through a photomask, and the unexposed composition is developed with a developing liquid with formation of a pattern.