Abstract: A primer/topcoat coil coating system employs crosslinkable branched hydroxyl-functional polyester-imide resins derived or derivable from a symmetric aromatic imide trial and a diacid or acid-producing derivative. The primer resin has a hydroxyl number greater than about 90 but not more than about 215, the topcoat resin has a hydroxyl number greater than about 100 but not more than about 215, and the primer and topcoat can each be hardened in 30 seconds or less to provide a coating having at least 0T flexibility with no tape off and at least 2H pencil hardness.

Abstract: High molecular weight polyester polymers are prepared in syrup form from an ester oligomer. The oligomer is converted to the polymer by polycondensation at atmospheric pressure and elevated temperature in a nonreactive carrier capable of forming an azeotrope with water. The ester oligomerization or polycondensation reactions desirably are monitored using a non-viscometric technique. The process has a rapid cycle time. The syrup contains the polymer and the nonreactive carrier, and may more conveniently be used to make initially non-solid products such as polyester coatings than is the case when employing pelletized solid polyester resins.

Abstract: Medium and high molecular weight polyester polymers are prepared in syrup form from an ester oligomer. The oligomer is converted to the polymer by polycondensation at elevated pressure and elevated temperature in a nonreactive carrier capable of forming an azeotrope with water. The ester oligomerization or polycondensation reactions desirably are monitored using a non-viscometric technique. The process has a rapid cycle time. The syrup contains the polymer and nonreactive carrier, and may more conveniently be used to make initially non-solid products such as polyester coatings than is the case when employing pelletized solid polyester resins.

Abstract: A gel coat for a surface of a composite article contains a curable urethane acrylate resin preferably based on aliphatic polyester polyols and aliphatic polyisocyanates. The gel coat provides a surface that has high gloss and color retention after prolonged exposure to ultraviolet radiation. The gel coat composition contains resin and acrylic diluents, including optional difunctional and trifunctional diluents. The gel coat is optionally pigmented to produce an article that may be used without further surface treatment.