Photopolymerizable epoxy resin composition

Claim 1

A photopolyermizable epoxy resin composition comprising (A) an epoxy resin having more than one oxirane group and (B) a salt comprised of an anion of a heteropoly acid and an aromatic sulfonium or an aromatic iodonium cation, wherein (i) said anion is selected from the group consisting of a phosphotungstate anion, a phosphomolybdate anion, a tungstogermanate anion, silicotungstate anion and a silicomolybdate anion, and (ii) said salt is selected from the group consisting of (a) a compound represented by the formula: ##STR8## wherein Ar 1 to Ar 3 are the same or different from each other, and each represents an aromatic group which is unsubstituted or substituted with at least one substituent selected from the group consisting of a halogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryloxy group, an arylthio group and a nitro group; X m ⊖ represents said anion; and m is an integer of 3 to 5, and (b) a compound represented by the formula ##STR9## wherein Ar 4 and Ar 5 are the same or different from each other, and each represents a substituted or unsubstituted aromatic group or heterocyclic group having 6 to 20 carbon atoms; Z represents the optional presence of an oxygen atom, a sulfur atom, ##STR10## where R 1 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an acyl group having 1 to 5 carbon atoms, and R 2 and R 3 are the same or different from each other, and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms; X m ⊖ represents said anion; m is the same as defined above; n is an integer of 0 or 1; and the dotted line represents the optional presence of bonding when n=1.