Patent ID: 6576051
Filing Date: 2003-06-10
Classification: C01P,C08F,C08K,C09C,C09D

Abstract:
A composition comprising at least one composite particle;wherein said composite particle comprises: a) a titanium dioxide particle; and b) two-phase polymer particles adsorbed on the surface of said titanium dioxide particle; wherein said composite particle is formed in an aqueous mixture consisting essentially of at least one said titanium dioxide particle, a multiplicity of said two-phase polymer particles, and optionally, dispersant, and the weight ratio of said multiplicity of said two-phase polymer particles to at least one said titanium dioxide particle in said aqueous mixture is in the range of 1:20 to 1:2; wherein each of said two-phase polymer particles, which contain ethylenically unsaturated monomer as polymerized units, comprises: i) a soft polymer phase with a glass transition temperature less than or equal to 40Â° C., and ii) a hard polymer phase with a glass transition temperature greater than 40Â° C.; wherein the difference between the glass transition temperature of said hard polymer phase and said soft polymer phase is at least 10Â° C.; wherein the average weight ratio of said hard polymer phase to said soft polymer phase is in the range of 10:1 to 1:5; and wherein A) each of said two-phase polymer particles includes at least one element selected from the group consisting of: at least one phosphorus functional monomer as a polymerized group, at least 5 weight % of at least one carboxylic acid monomer as a polymerized group, based on weight of said two-phase polymer particles, at least one acid macromonomer as a polymerized group, and a water soluble polymer chemically bonded to said two-phase polymer particles wherein said water soluble polymer has a molecular weight of at least 1500 prior to bonding to said two-phase polymer particles and contains at least one moiety adsorbable to said titanium dioxide particle; or B) said two-phase polymer particles and said titanium dioxide particle have opposite charges.