Patent ID: 7344752
Filing Date: 2008-03-18
Classification: C08F

Abstract:
1. A process for producing a core-shell polymer that comprises: (1) preparing a monomer solution which is comprised of (a) a first monomer, (b) a conjugate acid of a surfactant with a pKa of less than 14, and (c) a controlled free radical polymerization agent; (2) preparing an aqueous medium which is comprised of (a) water, and (b) a conjugate base of a weak acid wherein the pKb of the base is less than 14, and (3) mixing the monomer solution with the aqueous medium under conditions that result in the in-situ formation of an emulsifier to produce a polymerization medium, (4) initiating free radical polymerization within the polymerization medium in the presence of a free radical control agents to produce a solution of polymeric particles, (5) adding a second monomer to the solution of polymeric particles, and (6) allowing polymerization to proceed in the presence of the free radical control agent to produce the polymer, wherein the core-shell polymer includes a core which is comprised of repeat units of the first monomer and a shell which is comprised of repeat units of the second monomer, wherein the core is at least partially engulfed by the shell, wherein the core is a crosslinked polymer core, wherein the crosslinked polymer core has a glass transition temperature such that the crosslinked polymer core does not soften at service temperatures up to about 150° C., and wherein the core is incompatible with the shell.