ACTIVE ESTER RESIN, METHOD FOR PRODUCING SAME, THERMOSETTING RESIN COMPOSITION, CURED PRODUCT THEREOF, SEMICONDUCTOR SEALING MATERIAL, PREPREG, CIRCUIT BOARD, AND BUILD-UP FILM

摘要

A low dielectric constant, a low dielectric loss tangent, and heat resistance are achieved. An active ester resin that has 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 the amount of the component (a2) is 0.4 to 0.95 moles and the amount of the component (a3) is 0.3 to 0.025 moles per mole of phenolic hydroxyl groups of the component (a1) is used as a curing agent for epoxy resin. The polyfunctional phenolic compound (a1) is represented by structural formula (1) below:
(where 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 the average thereof is in a range of 0.5 to 10).