Storage stable, one package, heat curable polyurea/urethane coating compositions and method of preparation

A method for preparing a one package, storage stable, heat-curable poly urea/urethane coating composition, said method comprising:

• (a) forming a liquid mixture of a poly aliphatic isocyanate compound of the formula:
• ##STR8## wherein R and R' are each, independently, selected from hydrogen, alkyl and substituted alkyl and X is a bridging means selected from divalent aliphatic, cyclo-aliphatic or aromatic groups, or a polymeric adduct of said aliphatic isocyanate compound possessing poly aliphatic isocyanate functionality in a suitable solvent;
• (b) cooling liquid mixture (a) to a temperature of from about 0.degree. C. to about 10.degree. C.;
• (c) forming a liquid mixture of at least one monomeric or polymeric compound containing a plurality of isocyanate-reactive hydrogens in a suitable solvent;
• (d) adding the mixture of step (c) to the cooled mixture of step (b) to form a reaction mixture;
• (e) permitting the reaction mixture of step (d) to come to room temperature and allowing the reaction to continue at room temperature for a time sufficient to provide a prepolymer solution containing about 30% to about 80% by weight solids;
• and
• (f) thereafter, adding to said prepolymer solution formed in step (e), a minor effective amount of a polymerization catalyst to provide a storage stable, one package, heat-curable poly urea/urethane coating composition.