Resinous composition of phosphatized polyester polymers and coating compositions for improved adhesion

Abstract

An adherent coating composition and method has a resin composition that is the polymerization reaction product of one or more polyhydric alcohols and two polybasic carboxylic acids and salt forming compounds of phosphorus. The carboxylic acid is comprised of at least adipic acid and phthalic anhydride in a mole ratio in the range of about 0.6:1 to about 3:1, and the phosphorus compound is present in the range of about 1 to about 5 weight percent of the resin composition. The resin composition can have a weight average molecular weight in the range of about 1100 to about 4000 and an acid value in the range of about 5 to about 40. Optionally, the resin can have up to about 35 weight percent of tetrahydrophthlic anhydride. The resin composition is ungelled and curable with crosslinking agents in an amount of about 30 to about 90 weight percent of resin to about 10 to about 45 weight percent of the crosslinking agent. These weight percents are based on the resin solids of the coating composition which is useful as a primer coating for substrates such as metal.

Dependencies are inferred from the claim text.