Patent ID: 8399579

Claim:
A process for preparing an aqueous composite-particle dispersion comprising an addition polymer and finely divided inorganic solid particles, the process comprising: distributing at least one ethylenically unsaturated monomer dispersely in aqueous medium; and polymerizing the at least one monomer by free-radical aqueous emulsion polymerization with at least one free-radical polymerization initiator in the presence of at least one dispersely distributed, finely divided inorganic solid and at least one dispersant, a) wherein 1% to 1000% by weight of an inorganic solid having an average particle size ≦100 nm and 0.05% to 2% by weight of a free-radical polymerization initiator, based on a total amount of ethylenically unsaturated monomers, are employed, b) wherein at least a portion of the inorganic solid is comprised in an initial charge into the aqueous medium polymerization form in the form of an aqueous dispersion of solids, subsequently wherein, after the initial charge, the polymerizing comprises c) metering a total of ≧0.01% and ≦20% by weight of the total monomer amount while metering ≧60% by weight of a total amount of the free-radical polymerization initiator into the aqueous dispersion of solids resulting after the initial charge, and polymerizing the at least one ethylenically unsaturated monomer metered in, under polymerization conditions, up to a monomer conversion of ≧80% by weight, and subsequently d) metering any remainder of the inorganic solid, any remainder of the free-radical polymerization initiator, and the remainder of the at least one ethylenically unsaturated monomer into a resultant polymerization mixture under polymerization conditions, and carrying out polymerization to a monomer conversion of ≦90% by weight, and wherein the polymerizing steps c) and d) generate the aqueous composite-particle dispersion having a coagulum content of ≦0.5% by weight.