Patent ID: 6930141

Claim:
An aqueous polymer blend composition comprising: i) from 2 to 30 weight % of hard polymer particles; and ii) from 70 to 98 weight % of soft polymer particles; based on the total weight of said hard polymer particles and said soft polymer particles; wherein said soft polymer particles have a glass transition temperature (T g ) in the range of from −20° C. to 25° C., and said hard polymer particles have a T g of greater than 25° C. and at least 10° C. greater than said T g of said soft polymer particles; wherein said soft polymer particles comprise as copolymerized units, from 70 to 99.7 weight % monoethylenically unsaturated (meth)acrylic monomer, from 0.3 to 10 weight % monoethylenically unsaturated acid monomer; and from 0 to 29.7 weight % third monomer, based on weight of said soft polymer particles; wherein said hard polymer particles have a weight average molecular weight of at least 100,000; and wherein: a) at least 40 weight % of each of said soft polymer particles, based on weight of said soft polymer particles, is formed by redox polymerization; or b) at least 40 weight % of each of said soft polymer particles is polymerized in the presence of at least 5 weight % of added monomer that remains unreacted, based on accumulated weight of said added monomer, said added monomer being selected from said monoethylenically unsaturated (meth)acrylic monomer, said monoethylenically unsaturated acid monomer, said third monomer, and mixtures thereof.