Fluoro-alkyl ester-terminated linear aromatic polyester of enhanced hydrolytic stability

A linear aromatic polyester consisting of monomer residues of bisphenol A and a dicarboxylic acid selected from isophthalic acid, terephthalic acid and mixtures thereof containing about 5 to 100 mole percent, based on the total end groups in the polyester, of carboxylate ester end groups of monofunctional saturated acyclic aliphatic alcohol, the aliphatic residue of which contains only fluorine substituents or only fluorine and hydrogen substituents and 3 to 20 carbon atoms.

In the process of preparing a linear aromatic polyester which comprises monomer residues of a bisphenol and a dicarboxylic acid by the polymerization esterification reaction of said bisphenol and a diacyl halide of said dicarboxylic acid, the improvement wherein a minor molar proportion, based on the molar proportion of the diacyl halide, of a fluorine-substituted saturated monofunctional aliphatic alcohol of 1 to 45 carbon atoms is reacted into the polyester.