Carboxy resins of low equivalent weight per carboxyl group are synthesized
by reacting a compound having two or more isocyanate groups with a compound having
one hydroxyl group and two or more carboxyl groups. In a preferred embodiment,
the compound having isocyanate groups is an isocyanurate derivative of a diisocyanate.
The compound having isocyanate groups and the compound having one hydroxyl group
and two or more carboxyl groups are reacted under conditions where reaction of
carboxyl groups with isocyanate is substantially avoided. In another aspect of
the invention, coating compositions are provided that contain in addition to the
carboxy resin, a second component having a number of functional groups that are
reactive with the carboxyl groups on the carboxy resin.