Abstract: A heat-curable resin composition obtained by mixing (A) a polyester resulting from the depolymerization of a polyester of a high degree of polymerization comprising an aromatic dicarboxylic acid and an aliphatic dialcohol using a compound containing about 2 to about 12 carboxyl groups per molecule with (B) a polyoxirane compound containing about 2 to about 100 oxirane groups per molecule. A heat-curable resin composition obtained by adding to the above resin composition a salt formed between an aliphatic monocarboxylic acid containing 2 to 20 carbon atoms and an element of Group II of the Periodic Table as a curing accelerator is an especially superior material for powder paints. Powder paints prepared from these heat-curable resin compositions provide coatings having superior appearance and properties upon baking after coating by a method such as an electrostatic spray coating method or a fluidized dip coating method.

Abstract: A polyester resin composition suitable for preparing a powder paint, obtained by mixing a polyester, which is obtained by depolymerizing a polyester having a high degree of polymerization with an intrinsic viscosity of about 0.4 or more with at least one of a substantially nonvolatile alcohol and an ester having at least one alcoholic hydroxyl group in the same molecule, melts at a temperature between about 45.degree. C and about 120.degree. C and has terminal hydroxyl groups and an average degree of polymerization ranging from about 5 to about 50, with a polyisocyanate blocked with an alkyl p-hydroxybenzoate by melting. The polyester resin composition can be readily pulverized, has no blocking property and has the fluidity at relatively low temperatures sufficient to facilitate pigmentation, and can form beautiful coatings. The coatings have good resistance to weathering, solvents, humidity and fouling, and excellent adhesion to a metal.