Latent curing agents for epoxy resins

A latent curing agent for epoxy resins which comprises an addition compound obtained by reacting (a) a polyfunctional epoxy compound, (b) a compound having at least one functional group of OH group, SH group, COOH group and CONHNH.sub.2 group together with a tertiary amino group in the molecule, and (c) an organic compound having two or more active hydrogen atoms in the molecule (excluding a compound having an epoxy group or tertiary amino group) in a ratio of 0.8 to 2.5 equivalent in component (a) for 1 equivalent of the total active hydrogen in components (b) and (c), the molar ratio of (c) to (b) being 0.2:1 to 1:1, and said addition product having a softening point of 60.degree. to 180.degree. C.

A curable epoxy resin composition comprising (1) an epoxy resin having an average of more than one epoxy group per molecule and (2) an addition product obtained by reacting (a) a polyfunctional epoxy compound and (b) a compound having at least one functional group of OH group, SH group, COOH group and CONHNH.sub.2 group together with a tertiary amino group in the molecule in a ratio of 0.8 to 2.5 equivalent of epoxy group in compound (a) for 1 equivalent of active hydrogen in compound (b), said addition product having a softening point of 60.degree. to 180.degree. C.

A curable epoxy resin composition comprising (1) an epoxy resin having an average of more than one epoxy group per molecule and (2) an addition compound obtained by reacting (a) a polyfunctional epoxy compound, (b) a compound having at least one functional group of OH group, SH group, COOH group and CONHNH.sub.2 group together with a tertiary amino group in the molecule, and (c) an organic compound having two or more active hydrogen atoms in the molecule (excluding a compound having an epoxy group or tertiary amino group) in a ratio of 0.8 to 2.5 equivalent in component (a) for 1 equivalent of the total active hydrogen in components (b) and (c), the molar ratio of (c) to (b) being 0.2:1 to 1:1, and said addition product having a softening point of 60.degree. to 180.degree. C.

A cured epoxy resin composition comprising (1) an epoxy resin having an average of more than one epoxy group per molecule and (2) an addition product obtained by reacting (a) a polyfunctional epoxy compound and (b) a compound having at least one functional group of OH group, SH group, COOH group and CONHNH.sub.2 group together with a tertiary amino group in the molecule in a ratio of 0.8 to 2.5 equivalent of epoxy group in compound (a) for 1 equivalent of active hydrogen in compound (b), said addition product having a softening point of 60.degree. to 180.degree. C.

A cured epoxy resin composition comprising (1) an epoxy resin having an average of more than one epoxy group per molecule and (2) an addition compound obtained by reacting (a) a polyfunctional epoxy compound, (b) a compound having at least one functional group of OH group, SH group, COOH group and CONHNH.sub.2 group together with a tertiary amino group in the molecule, and (c) an organic compound having two or more active hydrogen atoms in the molecule (excluding a compound having an epoxy group or tertiary amino group) in a ratio of 0.8 to 2.5 equivalent in component (a) for 1 equivalent of the total active hydrogen in components (b) and (c), the molar ratio of (c) to (b) being 0.2:1 to 1:1, and said addition product having a softening point of 60.degree. to 180.degree. C.