Patent ID: 8003738

Claim:
A method of producing aqueous secondary dispersions of water-insoluble copolymers, comprising a) polymerization of ethylenically unsaturated monomers M by a free-radical solution polymerization in an organic, water-miscible solvent or in a mixture of water with an organic, water miscible solvent as polymerization medium, wherein the fraction of water in the mixture with the organic, water miscible solvent is not more than 30% by weight, where the monomers M comprise: i. 10 to 60% by weight, based on the total amount of monomers M, of at least one monoethylenically unsaturated monomer M1 with a solubility in water of not more than 10 g/l at 25° C. and 1 bar and ii. 40 to 90% by weight, based on the total amount of monomers M, of at least one hydrophilic, monoethylenically unsaturated, nonionic monomer M2 with a solubility in water of at least 80 g/l at 25° C. and 1 bar; and b) removing the organic solvent and adding water, wherein 1 to 20% by weight of the monomers M, based on the total amount of the monomers M, is a monomer composition M′ comprising more than 90% by weight of the at least one hydrophilic, monoethylenically unsaturated, nonionic monomer M2 with a solubility in water of at least 80 g/l at 25° C. and 1 bar, and wherein the monomer composition M′ is added to the polymerization medium after at least 80% of that fraction of monomers M which does not belong to the monomer composition M′ has been added to the polymerization vessel under polymerization conditions.