Patent ID: 8669333

Claim:
A thermosetting resin composition comprising an active ester resin (A) and an epoxy resin (B), wherein the active ester resin (A) is produced by reacting a phenolic hydroxyl group-containing resin (a1-1) with an aromatic monofunctional carboxylic acid or its chloride (a1-3) so as to leave phenolic hydroxyl groups in the resin (a1-1), and then reacting the reaction product with an aromatic dicarboxylic acid or aromatic dicarboxylic acid chloride (a1-2), the resin (a1-1) being a phenolic hydroxyl group-containing resin having a softening point of 70° C. to 200° C., phenolic hydroxyl groups at both ends thereof, and a structural unit (1′) as a repeat unit represented by general formula (1′) below, in the general formula (1′), a position of bonding to a naphthalene skeleton may be any one of the two rings constituting a naphthalene ring, in the general formula (1′), X represents a hydrogen atom or a structural site represented by general formula (1″) below, in the general formula (1′) and general formula (1″), R represents a structural site (α′) represented by general formula (2′) below, and p is an integer of 0 to 2, and in the general formula (2′), n is 1 or 2, the phenolic hydroxyl group-containing resin (a1-1) containing, in its molecular structure, the structural site (α′) at a ratio of 0.1 to 1.0 in terms of number of sites per naphthalene ring.