Photocurable resin composition for the preparation of a printed wiring board and process for the preparation of photocurable resin

A process for the preparation of a photocurable resin which comprises the steps of:

• 1) reacting a conjugated diene polymer or copolymer having a number average molecular weight of 500 to 5000 and vinyl content of at least 50 mole % with an .alpha.,.beta.-unsaturated dicarboxylic acid anhydride to obtain an adduct, said adduct containing the acid anhydride group ##STR6## 2) reacting said adduct from step 1) with a primary amine of formula
• R.sup.1 NH.sub.2 III
• wherein R.sup.1 is a hydrocarbon residue of 1-20 carbon atoms, in the amount of 20-80 mole %, based on said acid anhydride group, whereby an imide is formed containing the group (I) together with two by-products, water and a product containing a succinic acid group in the form of a half-amide according to the reaction hereinbelow ##STR7## and some of said adduct is unreacted;
• 3) reacting said water from step 2) with the unreacted adduct to convert said adduct into a product containing the succinic acid group according to the reaction hereinbelow:
• ##STR8## 4) Thermally dehydrating said product containing the succinic acid group from step 3) to regenerate said adduct containing the acid anhydride groups according to the reaction hereinbelow:
• ##STR9## 5) and reacting said adduct containing said acid anhydride groups from step 4) with an .alpha.,.beta.-unsaturated monocarboxylic acid ester having an alcoholic hydroxyl group of formula (IV) wherein each of R.sub.2 and R.sub.3 is a hydrogen atom or a methyl group and R.sub.4 is a hydrocarbon residue having at least two carbon atoms, to cause ring opening according to the reaction shown hereinbelow:
• ##STR10## whereby said photocurable resin is obtained containing said product containing the imide group (I) and a product II containing the half-ester group.