The invention relates to a polymer which can be obtained by radical emulsion polymerization of at least one acidic vinyl monomer or salt thereof, at least one non-ionic vinyl monomer, in particular preferably a hydrophobic non-ionic vinyl monomer, at least one monomer containing an unsaturated terminal group and a polyoxyalkyene portion, at least one crosslinking monomer, optionally a protective colloid, and is characterized in that the polymerization is controlled such that the gelling effect occurs at least at times, which is achieved by the monomer addition (dosing time) taking place for 40 minutes, particularly preferably for 30 minutes.
