Cationic polymerization initiator, curing agent composition and epoxy resin composition

摘要

Provided is a cationic polymerization initiator which, when used as a curing agent component of an epoxy resin composition, improves its storage stability without impairing the curability of the epoxy resin composition. This cationic polymerization initiator is a sulfonium salt compound represented by the following formula (1). (In the formula (1), R¹Represents a hydroxy group or a group represented by any one of the following formulas (2) to (5), R²Represents an alkyl group having 1 to 6 carbon atoms, and R³Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R⁴Represents an alkyl group having 1 to 6 carbon atoms, and R⁵Represents an unsaturated hydrocarbon group which may have a substituent. ) (In formulas (2) to (5), R⁶Each independently represent an aromatic or aliphatic hydrocarbon group which may have a substituent which may contain a hetero atom. )