Waterborne polyesters having improved saponification resistance

摘要

Substituted polycarboxylic acids or substituted anhydrides as acidifying agents stabilize a waterborne polyester from saponification, provided: (a) the acidification is carried out to an extent sufficient to provide an acid number of at least 40 milligrams KOH per gram of polyester resin; and (b) the substitution on the polycarboxylic acid or anhydride is either an alkenyl group having at least four carbon atoms or a cyclic group in which the ring is not aromatic. The relatively high acid number renders the polyester dispersible in water without the need to rely on surfactants.