Use of a coating layer on a paper substrate for blocking oxygen transfer through the coated paper substrate; wherein the coating layer on the paper substrate is obtainable by a process, which comprises the steps of: (a) providing a paper substrate with a surface; (b) applying onto the surface of the provided paper substrate an aqueous coating mass; and (c) drying of the paper substrate with the applied aqueous coating mass to obtain the coated paper substrate; wherein the aqueous coating mass contains an aqueous dispersion of a polymer P, which is obtainable by radically initiated emulsion polymerization of: (i) at least 25 parts by weight of an acrylate monomer, which is a C 1 -C 12 alkyl acrylate or a C 1 -C 12 alkyl methacrylate; (ii) 0 to 70 parts by weight of styrene; (iii) 0 to 5 parts by weight of an acidic monomer, which contains one ethylenically unsaturated group and at least one acid group; (iv) 0 to 3 parts by weight of a crosslinking monomer, which contains at least two non-conjugated ethylenically unsaturated groups; (v) 0 to 2 parts by weight of butadiene; (vi) 0 to 20 parts by weight of a further monomer, which contains an ethylenically unsaturated group and which is different to the acrylate monomer, styrene, the acidic monomer, the crosslinking monomer or butadiene; wherein the sum total of the parts by weight of the monomers (i), (ii), (iii), (iv), (v) and (vi) is always 100; in the presence of a first degraded starch. (a) providing a paper substrate with a surface; (b) applying onto the surface of the provided paper substrate an aqueous coating mass; and (c) drying of the paper substrate with the applied aqueous coating mass to obtain the coated paper substrate; wherein the aqueous coating mass contains an aqueous dispersion of a polymer P, which is obtainable by radically initiated emulsion polymerization of: (i) at least 25 parts by weight of an acrylate monomer, which is a C 1 -C 12 alkyl acrylate or a C 1 -C 12 alkyl methacrylate; (ii) 0 to 70 parts by weight of styrene; (iii) 0 to 5 parts by weight of an acidic monomer, which contains one ethylenically unsaturated group and at least one acid group; (iv) 0 to 3 parts by weight of a crosslinking monomer, which contains at least two non-conjugated ethylenically unsaturated groups; (v) 0 to 2 parts by weight of butadiene; (vi) 0 to 20 parts by weight of a further monomer, which contains an ethylenically unsaturated group and which is different to the acrylate monomer, styrene, the acidic monomer, the crosslinking monomer or butadiene; wherein the sum total of the parts by weight of the monomers (i), (ii), (iii), (iv), (v) and (vi) is always 100; in the presence of a first degraded starch. (i) at least 25 parts by weight of an acrylate monomer, which is a C 1 -C 12 alkyl acrylate or a C 1 -C 12 alkyl methacrylate; (ii) 0 to 70 parts by weight of styrene; (iii) 0 to 5 parts by weight of an acidic monomer, which contains one ethylenically unsaturated group and at least one acid group; (iv) 0 to 3 parts by weight of a crosslinking monomer, which contains at least two non-conjugated ethylenically unsaturated groups; (v) 0 to 2 parts by weight of butadiene; (vi) 0 to 20 parts by weight of a further monomer, which contains an ethylenically unsaturated group and which is different to the acrylate monomer, styrene, the acidic monomer, the crosslinking monomer or butadiene; wherein the sum total of the parts by weight of the monomers (i), (ii), (iii), (iv), (v) and (vi) is always 100; in the presence of a first degraded starch.