High solids urethane coatings prepared from a polylisocyanate _ and a polyhydroxy oligmer

A high solids thermosetting coating composition which contains greater than about 60 percent by weight of nonvolatile solids, and which exclusive of pigments, solvents, and other nonreactive components consists essentially of:

• (A) a polyhydroxy oligomer having a number average (M.sub.n) molecular weight of between about 300-2000 and comprising the reaction product of
• (i) an acid ester made by reacting:
• (a) a C.sub.3 -C.sub.10 aliphatic branched diol, and
• (b) an alkyl hexahydrophthalic anhydride,
• wherein (a) and (b) are combined in the reaction mixture in amounts sufficient to result in reaction in a molar ratio of greater than 1:1 up to 1:2;
• and
• (ii) a monoepoxide C.sub.2 -C.sub.10 monomer, wherein said monomer is included in an amount sufficient to provide reaction of about 1.0 epoxide group for each acid group of said acid ester;
• (B) a polyisocyanate crosslinking agent;
• (C) 0-50 weight percent based on the total weight of (A), (B), (C), and (D) of a hydroxy functional additive having a number average molecular weight (M.sub.n) of between about 150-6000;
• (D) up to 15 weight percent based on the total weight of (A), (B), (C) and (D) of a flow control additive;
• said polyisocyanate crosslinking agent having two or more reactive isocyanate groups per molecule and being included in said composition in an amount sufficient to provide between about 0.50 and about 1.6 reactive isocyanate groups per hydroxyl group present in said composition either on said polyhydroxy oligomer or as a hydroxyl group of said hydroxy functional additive.