A process for preparing an aqueous dispersion of a polymer P, which comprises the steps of - providing the monomers (a) vinyl acetate, (b) at least one acrylate monomer, which is a C 1 -C 10 alkyl acrylate or a C 1 -C 10 alkyl methacrylate, (c) at least one α,β-ethylenically unsaturated C 3 -C 6 carboxylic acid, (d) glycidyl methacrylate, glycidyl acrylate, allyl methacrylate or allyl acrylate, (e) optionally at least one ethylenically unsaturated sulfonic acid, and (f) optionally at least one ethylenically unsaturated other monomer, which is different to the monomers (a), (b), (c), (d) or (e), - emulsifying the monomers in an aqueous medium, and - polymerizing the monomers in the presence of a free-radical initiator and a starch derivative, wherein - the content of vinyl acetate is from 70 to 94.7 parts by weight of the monomers, - the content of the at least one acrylate monomer is from 5 to 25 parts by weight of the monomers, - the content of the at least one α,β-ethylenically unsaturated C 3 -C 6 carboxylic acid is from 0.1 to 10 parts by weight of the monomers, - the content of glycidyl methacrylate, glycidyl acrylate, allyl methacrylate or allyl acrylate is from 0.1 to 10 parts by weight of the monomers, - the optional content of the at least one ethylenically unsaturated sulfonic acid is from 0.1 to 5 parts by weight of the monomers, - the optional content of the at least one other ethylenically unsaturated monomer is from 0.1 to 15 parts by weight of the monomers, and the sum total of the parts by weight of the monomers (a), (b), (c), (d), (e) and (f) is 100 and wherein the content of the starch derivative is from 10 to 65 parts by weight of the sum total parts by weight of the monomers (a), (b), (c), (d), (e) and (f). - providing the monomers (a) vinyl acetate, (b) at least one acrylate monomer, which is a C 1 -C 10 alkyl acrylate or a C 1 -C 10 alkyl methacrylate, (c) at least one α,β-ethylenically unsaturated C 3 -C 6 carboxylic acid, (d) glycidyl methacrylate, glycidyl acrylate, allyl methacrylate or allyl acrylate, (e) optionally at least one ethylenically unsaturated sulfonic acid, and (f) optionally at least one ethylenically unsaturated other monomer, which is different to the monomers (a), (b), (c), (d) or (e), (a) vinyl acetate, (b) at least one acrylate monomer, which is a C 1 -C 10 alkyl acrylate or a C 1 -C 10 alkyl methacrylate, (c) at least one α,β-ethylenically unsaturated C 3 -C 6 carboxylic acid, (d) glycidyl methacrylate, glycidyl acrylate, allyl methacrylate or allyl acrylate, (e) optionally at least one ethylenically unsaturated sulfonic acid, and (f) optionally at least one ethylenically unsaturated other monomer, which is different to the monomers (a), (b), (c), (d) or (e), - emulsifying the monomers in an aqueous medium, and - polymerizing the monomers in the presence of a free-radical initiator and a starch derivative, - the content of vinyl acetate is from 70 to 94.7 parts by weight of the monomers, - the content of the at least one acrylate monomer is from 5 to 25 parts by weight of the monomers, - the content of the at least one α,β-ethylenically unsaturated C 3 -C 6 carboxylic acid is from 0.1 to 10 parts by weight of the monomers, - the content of glycidyl methacrylate, glycidyl acrylate, allyl methacrylate or allyl acrylate is from 0.1 to 10 parts by weight of the monomers, - the optional content of the at least one ethylenically unsaturated sulfonic acid is from 0.1 to 5 parts by weight of the monomers, - the optional content of the at least one other ethylenically unsaturated monomer is from 0.1 to 15 parts by weight of the monomers, and