PHOSPHORUS ACID FUNCTIONALIZED OPAQUE POLYMER

摘要

The present invention relates to opaque polymers functionalized with phosphorus acid groups, composites of TiO2 particles and the opaque polymers, and methods for their preparation. The composites are useful in coatings formulations and have been shown to exhibit improved hiding benefits in coated substrates over compositions containing non-functionalized opaque polymer and TiO2.

主权项

1. A method for preparing an aqueous dispersion of phosphorus acid functionalized core-shell polymer particles comprising the steps of a) contacting under emulsion polymerization conditions i) a first monomer emulsion with ii) an aqueous dispersion of carboxylic acid functionalized polymer particles having an average particle size of from 80 to 180 nm to form an aqueous dispersion of core-shell polymer particles; then b) plasticizing the shell portion of the core-shell polymer particles with a polymerizable plasticizing agent; then c) contacting the core-shell polymer particles with an aqueous base to swell the core without substantially polymerizing the plasticizing agent; then d) polymerizing the plasticizing agent;
wherein the first monomer emulsion comprises a) from 0.1 to 5 weight percent of a phosphorus acid monomer, based on the weight of the monomers in the first monomer emulsion; and b) from 50 to 99.8 weight percent of a first nonionic ethylenically unsaturated monomer which, when polymerized, has a Tg of at least 50° C. and a refractive index of at least 1.4; and c) from 0.1 to 15 weight percent of a carboxylic acid functionalized monomer; wherein the acid functionalized polymer particles comprise from 20 to 50 weight percent structural units of a carboxylic acid monomer, based on the weight of the polymer particles; and 50 to 80 weight percent of structural units of a second nonionic ethylenically unsaturated monomer; wherein the plasticizing agent comprises from 7 to 30 percent of a third nonionic ethylenically unsaturated monomer based on the weight of the polymer particles; wherein the phosphorus acid functionalized core-shell polymer particles have a average particle size after step d) in the range of 250 nm to 1.6 μm.