Polymer obtainable by radical emulsion polymerization of (A) at least one acidic vinyl monomer or salt thereof； (B) at least one nonionic vinyl monomer, particularly preferably a hydrophobic nonionic vinyl monomer； (C) at least one monomer containing an unsaturated end group and a polyoxyalkylene part； (D) at least one crosslinking monomer； and (E) optionally, a protective colloid, characterized in that the polymerization is controlled such that (F) the gel effect occurs, at least at times, achieved by adding monomers of type (A), (B), and (C) (dosing time) during 120 minutes； and such that (G) the crosslinking monomer (D) is added, at the very earliest, 10 minutes after the first addition of the monomers (A), (B), and (C).
