A process for the preparation of a copolymer composition CP) by free-radical copolymerization of a monomer composition comprising a) 70 to 100% by weight, based on the total weight of the monomers used for the polymerization, of acrylic acid, b) 0 to 30% by weight, based on the total weight of the monomers used for the polymerization, of at least one hydrophilic nonionic compound, different from a), having a free-radically polymerizable, α,β-ethylenically unsaturated double bond, c) 0 to 1% by weight, based on the total weight of the monomers used for the polymerization, of at least one free-radically polymerizable crosslinking compound which comprises at least two α,β-ethylenically unsaturated double bonds per molecule, by the method of precipitation polymerization in the presence of an auxiliary composition H) comprising H1) at least one compound with a block structure which comprises at least one hydrophobic group and at least one hydrophilic group, where the compound with a block structure H1) is selected from - polyisobutenyl alcohol alkoxylates, - polyisobutenyl amine alkoxylates, - reaction products of at least one polyisobutene with at least one carboxylic acid end group or a derivative thereof and at least one polyalkylene oxide with a terminal group reactive towards anhydride groups, - silicone compounds which have at least one polyether group, - reaction products of at least one compound which comprises at least one hydrophobic group and at least one group reactive towards isocyanate groups, at least one compound which comprises at least one hydrophilic group and at least one group reactive towards isocyanate groups, and at least one polyisocyanate, and H2) at least one basic compound different from H1), where the component H2) is selected from NH 3. 2 CO 3. NH 4 HCO 3. monoalkylamines, dialkylamines, trialkylamines, amino alcohols, nitrogen-containing heterocycles and mixtures thereof. a) 70 to 100% by weight, based on the total weight of the monomers used for the polymerization, of acrylic acid, b) 0 to 30% by weight, based on the total weight of the monomers used for the polymerization, of at least one hydrophilic nonionic compound, different from a), having a free-radically polymerizable, α,β-ethylenically unsaturated double bond, c) 0 to 1% by weight, based on the total weight of the monomers used for the polymerization, of at least one free-radically polymerizable crosslinking compound which comprises at least two α,β-ethylenically unsaturated double bonds per molecule, by the method of precipitation polymerization in the presence of an auxiliary composition H) comprising H1) at least one compound with a block structure which comprises at least one hydrophobic group and at least one hydrophilic group, where the compound with a block structure H1) is selected from - polyisobutenyl alcohol alkoxylates, - polyisobutenyl amine alkoxylates, - reaction products of at least one polyisobutene with at least one carboxylic acid end group or a derivative thereof and at least one polyalkylene oxide with a terminal group reactive towards anhydride groups, - silicone compounds which have at least one polyether group, - reaction products of at least one compound which comprises at least one hydrophobic group and at least one group reactive towards isocyanate groups, at least one compound which comprises at least one hydrophilic group and at least one group reactive towards isocyanate groups, and at least one polyisocyanate, and H2) at least one basic compound different from H1), where the component H2) is selected from NH 3. 2 CO 3. NH 4 HCO 3. monoalkylamines, dialkylamines, trialkylamines, amino alcohols, nitrogen-containing heterocycles and mixtures thereof. H1) at least one compound with a block structure which comprises at least one hydrophobic group and at least one hydrophilic group, where the compound with a block structure H1) is selected from - polyisobutenyl alcohol alkoxylates, - polyisobutenyl amine alkoxylates, - reaction products of at least one polyisobutene with at least one carboxylic acid end group or a derivative thereof and at least one polyalkylene oxide with a terminal group reactive towards anhydride groups, - silicone compounds which have at least one polyether group, - reaction products of at least one compound which comprises at least one hydrophobic group and at least one group reactive towards isocyanate groups, at least one compound which comprises at least one hydrophilic group and at least one group reactive towards isocyanate groups, and at least one polyisocyanate, and - polyisobutenyl alcohol alkoxylates, - polyisobutenyl amine alkoxylates, - reaction products of at least one polyisobutene with at least one carboxylic acid end group or a derivative thereof and at least one polyalkylene oxide with a terminal group reactive towards anhydride groups, - silicone compounds which have at least one polyether group, - reaction products of at least one compound which comprises at least one hydrophobic group and at least one group reactive towards isocyanate groups, at least one compound which comprises at least one hydrophilic group and at least one group reactive towards isocyanate groups, and at least one polyisocyanate, H2) at least one basic compound different from H1), where the component H2) is selected from NH 3. 2 CO 3. NH 4 HCO 3. monoalkylamines, dialkylamines, trialkylamines, amino alcohols, nitrogen-containing heterocycles and mixtures thereof.