LOW MOLECULAR WEIGHT HYDROXY FUNCTIONAL POLYESTERS FOR COATINGS

摘要

The polyester composition of this invention comprises a polyester oligomer having a number average molecular weight of from about 650 to about 950, a weight average molecular weight of from about 950 to about 1900, and a polydispersity of from about 1.45 to about 2. The hydroxyl value is from about 150 to about 275, and the acid number is less than about 7. Substantially all of the hydroxy groups are primary and from 0 to about 5% of the hydroxy groups are present as pendant hydroxy-alkyl groups. The polyester is formed by a two-stage reaction of monomers consisting of carboxylic anhydrides having from 4 to 34 carbon atoms and polyols having from 2 to 20 carbon atoms. From about 10 to about 50 % by weight of the monomers are anhydrides having the formula: <IMG> where R1 is a non-aromatic hydrocarbon radical having from 6 to 30 carbon atoms, R2 is hydrogen or a non-aromatic hydrocarbon radical having from 1 to 8 carbon atoms. The total number of carbon atoms in R1 and R2 is from 8 to 30 carbon atoms. The polyester in conjunction with a hydroxyl-reactive curative provides a coating composition.