The method of claim 24 wherein the epoxy resin is a diglycidyl ether of bisphenol A, the blocked isocyanate is an alkyl phenol blocked toluene diisocyanate, the curing agent is an alkylene amine havine the formula NH.sub.2 CH.sub.2 CH.sub.2CH.sub.2 O(CH.sub.2 CH.sub.2