Patent ID: 8227542
Filing Date: 2012-07-24
Classification: C08F,C08J,C08L,C09D,Y10T

Abstract:
1. An aqueous dispersion comprising polymeric particles, the particles comprising: a core stage polymer comprising, as polymerized units, from 5-100% by weight, based on the weight of the core, of at least one hydrophilic mono-ethylenically unsaturated monomer and from 0 to 95% by weight of at least one nonionic mono-ethylenically unsaturated monomer; from 10-80% by weight, based on total polymeric weight of the particles when dry, of a first shell stage polymer having a Tg of 50° C. or greater, the first shell stage polymer comprising when dry, at least one void, the void having a diameter of from 100 to 1200 nanometers, wherein the first shell stage polymer is formed by a polymerization of at least one mono-ethylenically unsaturated monomer and from 0.05 to 50% by weight, based on the total weight of the first shell stage polymer, of at least one multi-ethylenically unsaturated monomer; and from 20% to 90% by weight, based on the weight of the polymeric particles, of at least one second shell stage polymer comprising, as polymerized units, at least one mono-ethylenically unsaturated monomer, the second shell stage polymer substantially encapsulating the first shell stage polymer and having a Tg of from −60° C. to 50° C., wherein the second shell stage polymer is formed by a polymerization of the at least one mono-ethylenically unsaturated monomer in the presence of the first shell stage polymer, and further wherein at least 10% of the second shell stage polymer is formed by polymerization at a temperature of from 5° C. to 65° C., the temperature being at least 30° C. below the calculated Tg of the first shell stage polymer; wherein the aqueous dispersion has a monomodal particle size distribution; and wherein the aqueous dispersion has a BCOP hiding factor of at least 0.1.