Patent ID: 8283404

Claim:
An opacifying pigment encapsulated in polymer comprising: 1) a pigment particle having an average particle diameter of from 0.005 to 5 microns and an index of refraction of at least 1.8; 2) from 0.1% to 25% by weight, based on the weight of the pigment particle, of a water-soluble first polymer, the molecular weight of which is controlled by 0 to 10 weight percent, based on the weight of the water-soluble first polymer, of an alkyl mercaptan or an alcohol or a halogenated compound, which water-soluble first polymer consists essentially of: a) at least three moieties of a sulfur acid monomer or a salt thereof; and b) structural units of at least one other monomer selected from the group consisting of an amine functional monomer; styrene; vinyl toluene; vinyl acetate; vinyl versatate; acrylonitrile; (meth)acrylamide; C 1 -C 40 esters of (meth)acrylic acid; alcohol containing monomers; and ethylenically unsaturated mono-, di- and trialkyl esters of ethylenically unsaturated carboxylic acids and anhydrides; and 3) from 10% to 200% by weight, based on the weight of the pigment particle a second polymer that at least partially encapsulates the pigment particle.