Carboxylated diphenylether-formaldehyde copolymer resins and their preparation

Abstract

Novel copolymer resins having the repeating unit ##STR1## WHEREIN EACH R is independently alkyl of 1 to about 10 carbon atoms or halogen, z is oxygen or sulfur, the dashed line is an optional chemical bond, the group represented by z taken with the dashed line represents dibenzofuran and dibenzothiophene moieties, or mixtures thereof, each R" is hydrogen or ##STR2## wherein each R' is a hydrocarbon or substituted hydrocarbon radical of from 2 to about 11 carbon atoms, n averages about 3-10, each m is 0-2 and p and q are each 0 or 1 with the proviso that the sum of p and q has an average value of 0.1-1.0 and there is an average of at least one carboxyl group per polymer molecule, are prepared by reacting a mixture comprising a hydroxymethylated diphenylether-formaldehyde copolymer with an anhydride of the formula ##STR3## wherein R' is a hydrocarbon or substituted hydrocarbon radical of from 2 to about 11 carbon atoms, at a temperature between about 120.degree. and about 170.degree. C. The copolymer resins form stable aqueous solutions in the presence of base which, when heated in the presence of a water-soluble curing agent, such as hexamethoxymethylmelamine, yield glossy, flexible and impact-, solvent-, and water-resistant films.

Dependencies are inferred from the claim text.