Patent ID: 8227529

Claim:
An aqueous slurry comprising a finely divided filler which is at least partly coated with a composition comprising at least one water-soluble amphoteric copolymer and at least one latex wherein the aqueous slurry is obtained by a process comprising treating an aqueous slurry of a finely divided filler with at least one water-soluble amphoteric copolymer and at least one latex, wherein the water-soluble amphoteric copolymer is obtained by a process comprising copolymerizing a monomer mixture comprising (a) at least one N-vinylcarboxamide represented by formula (I) where R 1 and R 2 , independently of one another, are H or C 1 - to C 6 -alkyl, (b) at least one monomer which is selected from the group consisting of (b 1 ) monoethylenically unsaturated sulfonic acid, phosphonic acid, phosphoric acid ester, and derivatives thereof and (b 2 ) monoethylenically unsaturated monocarboxylic acid, monoethylenically unsaturated dicarboxylic acid, salts thereof and dicarboxylic anhydride, (c) optionally at least one monoethylenically unsaturated monomer differing from the components (a) and (b), and (d) optionally at least one compound which has at least two ethylenically unsaturated double bonds in the molecule, with the proviso that the monomer mixture comprises at least one monomer (b) having at least one free acid group or an acid group in salt form, or both, and subsequent partial or complete hydrolysis of the groups —CO—R 1 from the monomers (a) incorporated in the form of polymerized units in the copolymer.