The present invention relates to a polymer dispersion wherein the components of a physical mixture comprising (i) at least one unsaturated silane of the general formula (I): [H2C═CX(Y)n]Si(CH3)p(R)3-p in which X is a hydrogen atom or a methyl group, Y is a divalent group selected from —CH2— and —C(O)O—(CH2)3—, n is 0 or 1, R is an alkoxy group selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, and 2-methoxyethoxy, and p is 0 or 1, and (ii) at least one organosilane of the general formula (II): R1Si(CH3)q(R2)3-q in which R1 is a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms or is an aryl group or is a polyether group, R2 is an alkoxy group selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy and 2-methoxyethoxy, and q is 0 or 1, and/or at least one silicic ester of the general formula (III): Si(R3)4, in which groups R3 are identical or different and R3 is an alkoxy group selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy and isobutoxy, are incorporated into the framework of the polymer, a process for preparing such a polymer dispersion, and its use.