Patent ID: 7220815

Claim:
A sulfonated aliphatic-aromatic copolyester having a crystalline melting temperature T m and comprising an acid component, a glycol component and 0 to about 5.0 mole percent based on 100 mole % acid component of a polyfunctional branching agent selected from polyfunctional acid, glycol or mixtures thereof, wherein the acid component comprises a. about 94.9 to about 40.0 mole percent of an aromatic dicarboxylic acid component based on 100 mole percent total acid component, and b. about 5.0 to about 50.0 mole percent of an aliphatic dicarboxylic acid component based on 100 mole percent total acid component, and c. about 0.1 to about 5.0 mole percent of a sulfonate component based on 100 mole percent total acid component, and wherein the glycol component consists essentially of 1,4-butanediol.