Abstract: Low temperature curable unsaturated polyester powder coatings suited for heat sensitive substrates with improved surface cure through incorporation of active hydrogen groups into the unsaturated polyester molecule. The unsaturated polyesters containing active hydrogens are derived from ethylenically unsaturated polyfunctional carboxylic acids and active hydrogen containing polyols. Full cure on the surface is obtained without the need for polyethylene waxes or oxygen-reactive curative resins that are commonly employed in order to prevent atmospheric oxygen from inhibiting the free-radical induced cure at the surface of the coating.

Abstract: Filiform corrosion of aluminum and of chrome-plated steel is prevented by covering the surface of the bare metal with a powder coating containing a major amount of a thermosetting resin selected from the group consisting of polyurethanes, polyesters, and acrylics; a minor, adhesion promoting amount of an epoxy resin; and either an ultra-violet light absorber or a hindered amine light stabilizer or a mixture of both, and baking the coated article to give a clear coating on the metal.

Abstract: A filiform corrosion resistant aluminum automotive road wheel has a bare aluminum surface, optionally having a chromate conversion coating, which is covered with a thermoset clear coating. The thermoset clear coating is the thermally cured product of a powder coating composition consisting essentially of (1) a major amount of a thermosetting resin selected from the group consisting of polyurethanes, hydroxy functional polyesters, and glycidyl functional acrylic resins, (2) a curing agent, (3) from about 1% to about 5% by weight of the coating powder of an epoxy resin as an adhesion promoting additive, and (4) either an ultra-violet light absorber or a hindered amine light stabilizer or a mixture of both.