| 摘要 |
PROBLEM TO BE SOLVED: To provide an epoxy resin cured product that is superior in heat-resistance, is small in a change of heat-resistance after thermal hysteresis, and is low in a dielectric constant and dielectric loss tangent, and provide an active ester resin curing agent that provides the cured product.SOLUTION: This invention provides: an active ester resin curing agent that is a reactant of polycondensate (a) of α-naphthol compound, &bgr;-naphthol compound, and formaldehyde, and monocarboxylic acid compound or its halide (b), wherein the percentage of content of trimer is 15-35% and the percentage of content of dimer is 1-25% (both are area ratios based on GPC measurements), and at least one phenolic hydroxyl group included in the trimer and/or dimer is substituted by an ester forming structural moiety selected from the group consisting of benzoyl group, benzoyl group ring-substituted by 1-4C alkyl group, naphthoyl group, naphthoyl group ring-substituted by 1-4C alkyl group, and 2-6C acyl group; and an epoxy resin containing the curing agent. |
