Process for preparing blends of polyesters and acrylic polymers

Claim 1

A process comprising the steps of: (A) contacting substantially dry acrylic polymer with a solubilizing amount of an alkaline solution comprising an amine or ammonium compound dissolved in water so as to achieve an acrylic polymer solution having a pH of at least about 10, (B) heating the acrylic polymer solution formed by step (A) at a sufficient temperature to result in an acrylic polymer solution having a pH of less than about 9, (C) contacting the acrylic polymer solution formed by step (B) with a water dispersible polyester material having carbonyloxy linking groups in the linear molecular structure wherein up to 80% of the linking groups may be carboxylamido linking groups, said water-dispersible polyester material having an inherent viscosity of from about 0.1 to about 0.5 measured in a 60/40 parts by weight solution of phenol/tetrachloroethane at 25° C. and at a concentration of 0.25 grams of polymer in 100 mL of the solvent, said water-dispersible polyester material containing substantially equimolar proportions of acid equivalents (100 mol %) to hydroxy and amino equivalents (100 mol %), the polymer comprising the reaction products of (a), (b), (c) and (d) from the following components or ester forming or ester-amide forming derivatives thereof: (a) at least one dicarboxylic acid; (b) from about 12 to about 25 mol %, based on a total of all acid, hydroxyl and amino equivalents being equal to 200 mol %, of at least one difunctional sulfomonomer containing at least one metal cationic group attached to aromatic nucleus wherein the functional groups are hydroxy, carboxyl, or amino; (c) at least one difunctional reactant selected from a glycol or a mixture of a glycol and diamine having two --NRH groups, the glycol containing two --CH 2 --OH groups; and (d) from none to at least one difunctional reactant selected from a hydroxycarboxylic acid having one --CR 2 --OH group, an aminocarboxylic acid having one --NHR group, and an amino-alcohol having one --CH 2 --OH group and one --NHR group, or mixtures of said difunctional reactants, wherein each R is an H atom or an alkyl group of 1 to 4 carbon atoms, said contacting occurring under agitation and at a sufficient temperature of about 80° C. to about 99° C. to result in a polymer blend wherein the polyester is substantially completely dispersed in the acrylic polymer solution, and the weight ratio of acrylic polymer:polyester is about 1:99 to about 50:50, (D) cooling the polymer blend composition of step (C) to a temperature range of about 45° C. to less than about 80° C., wherein a C 1 -C 4 alcohol or a mixture of a C 1 -C 4 alcohol and propylene glycol is added at a concentration of about 2 to about 10% of the total polymer blend composition, (E) further cooling the polymer blend composition of step (C) to less than about 45° C., wherein the acrylic polymer is compatible with the polyester.