Abstract: A binder mixture is described comprising: an aqueous copolymer dispersion which has a glass transition temperature, Tg, of less than 10° C. and which is prepared by emulsion polymerization of a monomer mixture comprising: (i) at least 60% by weight, based on the total amount of monomers, of at least one vinyl ester; (ii) from 15 to 30% by weight, based on the total amount of monomers, of ethylene; (iii) from 0.05 to 5% by weight, based on the total amount of monomers, of an ethylenically unsaturated carboxylic acid having at least 4 carbon atoms; and (iv) from 0.05 to 5% by weight, based on the total amount of monomers, of an ethylenically unsaturated sulfonic acid or salt thereof.