Aqueous polymer dispersion comprising a) 10 to 55 % by weight based on the dispersion of at least one polymer P obtainable by the reaction of reactive monomers M, wherein the reactive monomers M comprise - 50 to 100 % by weight of at least one monomer M1 of the general formula H 2 C=CH-C OR wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms; and - 0 to 50 % by weight of at least one monomer M2, which is different from monomer M1; wherein the amounts of the monomers M1 and M2 are each based on the total amount of all reactive monomers M used in the reaction, wherein the polymer P has a weight-average molecular weight M w of 20,000 to 150,000 g/mol according to DIN 55672-1:1995-02; and wherein the polymer P is present in the form of particles having an average particle size d 50 of from 75 nm to 400 nm effected by Column Hydrodynamic Chromatography; b) 0 to 24.5 % by weight based on the total amount of the aqueous polymer dispersion of at least one with water miscible solvent, c) 0 to 30 % by weight based on the total amount of the aqueous polymer dispersion of at least one hydrophobic organic solvent, d) 10 to 30 % by weight based on the total amount of monomers M of at least one protective colloid, wherein the at least one protective colloid is a polymer obtained by the reaction of - 15 to 40 % by weight of acrylic acid, methacrylic acid, or a mixture thereof; and - 60 to 85 % by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or a mixture of two or more thereof, in polymerized form, wherein the given amounts are each based on the total amount of the at least one protective colloid; and e) 0 to 5 % by weight based on the total amount of the aqueous polymer dispersion of at least one surfactant. a) 10 to 55 % by weight based on the dispersion of at least one polymer P obtainable by the reaction of reactive monomers M, wherein the reactive monomers M comprise - 50 to 100 % by weight of at least one monomer M1 of the general formula H 2 C=CH-C OR wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms; and - 0 to 50 % by weight of at least one monomer M2, which is different from monomer M1; wherein the amounts of the monomers M1 and M2 are each based on the total amount of all reactive monomers M used in the reaction, wherein the polymer P has a weight-average molecular weight M w of 20,000 to 150,000 g/mol according to DIN 55672-1:1995-02; and wherein the polymer P is present in the form of particles having an average particle size d 50 of from 75 nm to 400 nm effected by Column Hydrodynamic Chromatography; - 50 to 100 % by weight of at least one monomer M1 of the general formula H 2 C=CH-C OR wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms; and - 0 to 50 % by weight of at least one monomer M2, which is different from monomer M1; b) 0 to 24.5 % by weight based on the total amount of the aqueous polymer dispersion of at least one with water miscible solvent, c) 0 to 30 % by weight based on the total amount of the aqueous polymer dispersion of at least one hydrophobic organic solvent, d) 10 to 30 % by weight based on the total amount of monomers M of at least one protective colloid, wherein the at least one protective colloid is a polymer obtained by the reaction of - 15 to 40 % by weight of acrylic acid, methacrylic acid, or a mixture thereof; and - 60 to 85 % by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or a mixture of two or more thereof, in polymerized form, wherein the given amounts are each based on the total amount of the at least one protective colloid; and - 15 to 40 % by weight of acrylic acid, methacrylic acid, or a mixture thereof; and - 60 to 85 % by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or a mixture of two or more thereof, in polymerized form, e) 0 to 5 % by weight based on the total amount of the aqueous polymer dispersion of at least one surfactant.