Patent ID: 8791214

Claim:
A active ester resin comprising a resin structure produced by reacting a polyfunctional phenolic compound (a1) with a monofunctional aromatic carboxylic acid or its chloride (a2) and an aromatic dicarboxylic acid or its chloride (a3) in such a manner that an amount of the monofunctional aromatic carboxylic acid or its chloride (a2) is 0.46 to 0.95 moles and an amount of the aromatic dicarboxylic acid or its chloride (a3) is 0.27 to 0.025 moles per mole of phenolic hydroxyl groups of the polyfunctional phenolic compound (a1), the polyfunctional phenolic compound (a1) being represented by structural formula (1) below: (wherein Ar represents a benzene ring, a naphthalene ring, a benzene ring nuclear-substituted by an alkyl group having 1 to 4 carbon atoms, or a naphthalene ring nuclear-substituted by an alkyl group having 1 to 4 carbon atoms; X represents a methylene group, a divalent cyclic aliphatic hydrocarbon group, a phenylene dimethylene group, or a biphenylene-dimethylene group; and n represents the number of repeating units and an average thereof is in a range of 0.5 to 10).