Abstract: To provide a polycarboxylic acid resin which is obtained by reacting an epoxy resin (a) having two glycidyl groups with, e.g. itaconic acid (b) and ethylenic monocarboxylic acid (c) to obtain linear adduct polymer (A); and by reacting linear adduct polymer (A) with polybasic acid anhydride (d). According to the present invention, there are provided a polycarboxylic acid resin, its composition, and its cured product. The composition can facilely be dried upon preliminary heating and show an improved tack-free property, an excellent photo-curing property, an excellent development property in an aqueous alkali solution, and excellent physical properties such as electrical, mechanical, heat resistance, solvent resistance, adhesiveness, flexibility, etc.

Abstract: To provide a polycarboxylic acid resin which is obtained by reacting an epoxy resin (a) having two glycidyl groups with, e.g. itaconic acid (b) and ethylenic monocarboxylic acid (c) to obtain linear adduct polymer (A); and by reacting linear adduct polymer (A) with polybasic acid anhydride (d). According to the present invention, there are provided a polycarboxylic acid resin, its composition, and its cured product. The composition can facilely be dried upon preliminary heating and show an improved tack-free property, an excellent photo-curing property, an excellent development property in an aqueous alkali solution, and excellent physical properties such as electrical, mechanical, heat resistance, solvent resistance, adhesiveness, flexibility, etc.