Aqueous dispersion of opacifying pigment-binder hybrid polymer particles

A composition comprising an aqueous dispersion of:

• a) multistage polymer particles comprising 1) a water-occluded core comprising from 20 to 60 weight percent structural units of a salt of a carboxylic acid monomer and from 40 to 80 weight percent structural units of a nonionic monoethylenically unsaturated monomer;
• 2) a polymeric shell having a calculated Tg in the range of from 90° C. and 110° C.;
• and 3) a film-forming polymeric binder layer superposing the shell, wherein the polymeric binder layer comprises structural units of at least one monoethylenically unsaturated monomer and has a Tg of not greater than 35° C.;
• wherein:
• i) at least 95 weight percent of the shell comprises structural units of methyl methacrylate, styrene, and trimethylolpropane trimethacrylate;
• ii) the shell comprises from 0.5 to 6 weight percent structural units of trimethylolpropane trimethacrylate;
• iii) the weight-to-weight ratio of the structural units of methyl methacrylate to styrene in the shell is in the range of from 35:65 to 55:45;
• iv) the ratio of the weight of structural units of monomers of the core to the weight of the shell in the multistage polymer particles is in the range of 1:12 to 1:16;
• v) the weight-to-weight ratio of the polymer binder to the sum of the weight of the shell and the weight of the structural units of monomers in the core in the multistage polymer particles is in the range of 1:1 to 3.5:1;
• vi) the shell comprises less than 2 weight percent structural units of acrylonitrile;
• and
• vii) the z-average particle size of the multistage polymer particles is in the range of from 300 nm to 750 nm.