Patent ID: 7629414

Claim:
An aqueous dispersion of polymeric particles, the particles comprising: a core stage polymer comprising, as polymerized units, from 5 to 100% by weight, based on the weight of the core, of at least one hydrophilic monoethylenically unsaturated monomer and from 0 to 95% by weight of at least one nonionic monoethylenically unsaturated monomer; from 25% to 33% by weight, based on the weight of the polymeric particles, of a first shell stage polymer comprising, as polymerized units, at least one monoethylenically unsaturated monomer and at least one multi-ethylenically unsaturated monomer present in an amount of from 0.05% to 90% by weight, based on the total weight of the first shell stage polymer, and when dry, at least one void, the void having a diameter of from 100 to 1200 nanometers; and from 67% to 75% 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 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., the second shell stage polymer formed in a presence of the first shell stage polymer.