Process for preparing sulfo-polyester/acrylic resin blends without volatile organic compounds
AssigneeEastman Chemical Company
InventorMahendra K. Sharma
Life of this patent
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Abstract
This invention relates to a process for preparing aqueous blends of sulfo-polyesters and solid acrylic resins without volatile organic compounds (VOC's) and surfactants. More specifically, the acrylic resins are characterized by an inverse relationship between the molecular weight and acid number of the resin, and the sulfo-polyesters contain at least 12 mole percent of a difunctional sulfomonomer. The aqueous sulfo-polyester/acrylic resin blends of the present invention are useful in inks, overprint varnishes, primers, paints, and coatings.
Claims19
A process for preparing aqueous sulfo-polyester/acrylic resin blends without volatile organic compounds, said process comprising the following steps:
- (A) contacting a solid acrylic resin having a weight average molecular weight of 1,000 to 9,000 and an acid number of 140 to 250 with a solubilizing amount of an alkaline solution comprising an amine or ammonium compound dissolved in water so as to achieve an acrylic resin solution having a pH of at least 8, said acrylic resin comprising repeating units of the formula ##STR3## wherein R is selected from the group consisting of hydrogen and an alkyl group having 1 to 20 carbon atoms, and R.sup.1 is selected from the group consisting of hydrogen and methyl, provided that the molecular weight and acid number of the acrylic resin is inversely related;
- (B) heating the acrylic resin solution of step (A) at a temperature of 60.degree. C. to 99.degree. C. to result in an acrylic resin solution having a pH of 7.5 to 9;
- (C) contacting the acrylic resin solution of step (B) with a water dispersible polyester consisting essentially of repeat units from:
- (a) a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and combinations thereof;
- (b) a diol;
- and
- (c) a difunctional sulfomonomer containing at least one sulfonate group attached to an aromatic nucleus wherein the functional groups are hydroxy, carboxy or amino, provided the difunctional sulfomonomer is present in an amount from 12 to 25 mole percent based on 100 mole percent dicarboxylic acid and 100 mole percent diol;
- said contacting occurring under agitation and at a temperature of 60.degree. C. to 99.degree. C. to result in a polymer blend wherein the sulfo-polyester is dispersed in the acrylic resin solution, and the weight ratio of acrylic resin to sulfo-polyester is 10:90 to 90:10;
- and
- (D) cooling the polymer blend while applying agitation.
Dependencies are inferred from the claim text.