PURPOSE: A photosetting resin composition, capable of forming a coat with excellent adhesion to a base material, which is prepared by compounding a mixture of an unsaturated polyester, a polymerizable monomer and a photosensitizer with a mixture of an epoxy resin and a photosensitive aromatic onium salt.
CONSTITUTION: An unsaturated polyester (or unsaturated epoxy ester) of average MW 300W1,500 per α,β-unsaturated double bond is diluted with a monomer (e.g., styrene) having 1W4 unsaturated double bonds to obtain a mixture about 1W5 times as heavy as the polyester, and then about 0.5W10wt% radical photosensitizer (e.g., benzoin) is added, to prepare component (A). On the other hand, about 0.5W10wt% photosensitive aromatic onium salt of a Group VIa or Group Va element (e.g., triphenylsulfonium tetrafluoro borate) is added to an epoxy resin (e.g., a bisphenol A-type epoxy resin) having at least two oxirane rings, to prepare component (B). Then the both components are compounded in a proportion of A/B of 90/10W10/90, in weight.
ISOBE ASAO
KOIBUCHI SHIGERU
