PURPOSE: The titled composition excellent in cracking resistance and thermal shock resistance and stable to heat, oxidative degradation and photodegradation, prepared by mixing a specified polyepoxyurethane compound with a dicarboxylic acid anhydride and a dihydrazide compound.

CONSTITUTION: A polyepoxyurethane compound (A) is obtained by reacting 0.2W 4 equivalent of the alcoholic hydroxyl groups of an alcoholic hydroxyl group- containing polyepoxy compound such as a diglycidyl ether of average MW ≥400, obtained by reacting disphenol A with epichlorohydrin with 1 equivalent of the isocyanato groups of a 4,4'-alkylidenedicyclohexyl diisocyanate compound of the formula (wherein R is H or CH3). Component a is mixed with (B) such an amount of a curing agent comprising 100pts.wt. dicarboxylic acid anhydride (e.g., phthalic anhydride) and 0.5W50pts.wt. dihydrazide compound (e.g., succinic acid dihydrazide) that the total number of acid anhydride groups and dihydrazide groups per epoxy group is 0.3W1.5.