CURING AGENT FOR EPOXY RESIN, RESIN COMPOSITION, PRODUCTION OF CURED MATERIAL AND CURED MATERIAL

PROBLEM TO BE SOLVED: To obtain the subject curing agent maintaining low-temperature curing properties and high-speed curing properties in a level equal to or higher than those of conventional curing agents, capable of improving mechanical strength, chemical resistance and water resistance of a cured material, by using a mercapto compound having a specific structure. SOLUTION: This curing agent comprises a compound of formula I ((n) is an integer of >=5; X is the residue after removal of (n) active hydrogen atoms from a compound containing (n) or more active hydrogen atoms). Among the compounds of the formula I, a compound of formula II (Q is CH2 CHCH2 SH; a group of formula III is a group in which the residue X is the residue of a compound having a chain structure and/or a repeated unit structure and (s)Q groups ((s) is 1 or 2) are present in each of both the end organic groups Z and one Q is present in (r) organic groups Z ; (n), (r) and (s) satisfy n=r+2s) is preferable. The compound of formula I is obtained, for example, by adding a compound of formula I (n) or more epichlorohydrin molecules to an active hydrogen compounds such a saccharide, dehydrochlorinating to give a polyepoxy compound and subjecting the hydrogen sulfide to addition reaction to the compound.