Patent ID: 6139961
Filing Date: 2000-10-31
Classification: C08F,C09D,D21H,Y10T

Abstract:
A hollow sphere organic pigment formed by(a) forming emulsion-polymerized multistaged polymer particles comprising(1) a hydrophilic core polymer formed from 5% to 100% by weight, based on the total weight of said core polymer, of a hydrophilic monoethylenically unsaturated monomer and from 0% to 95% by weight, based on the total weight of said core polymer, of at least one nonionic monoethylenically unsaturated monomer;(2) a first shell polymer formed from 90% to 99.9% by weight, based on the total weight of said first shell polymer, of at least one nonionic monoethylenically unsaturated monomer and from 0.1% to 10% by weight, based on the total weight of said first shell polymer, of an acid functional monoethylenically unsaturated monomer, wherein said first shell polymer fully encapsulates said core polymer, wherein the ratio of the weight of said core polymer to the weight of said first shell polymer is from 1:2 to 1:100, and wherein said first shell polymer has a glass transition temperature greater than 50.degree. C.; and(3) a second shell polymer formed from 93% to 99.9% by weight, based on the total weight of said second shell polymer, of at least one nonionic monoethylenically unsaturated monomer and from 0.1% to 7% by weight, based on the total weight of said second shell polymer, of an acid functional monoethylenically unsaturated monomer, wherein said second shell polymer is formed in the presence of said first shell polymer, and wherein said second shell polymer has a glass transition temperature from -15.degree. C. to -50.degree. C., and wherein said second shell polymer is at least 15% by weight of the total weight of said first shell polymer and said second shell polymer; and(b) neutralizing said particles formed with a base so as to swell said core and form particles containing a void.