Aq. polymer dispersions, obtd. by radical polymerisation of monomers in aq. emulsion in presence of a polymeric protective colloid (A) with an average mol. wt. (Mw) of >20,000. Colloid (A) is a copolymer of 5-50 wt. % unsatd. monomer(s) with acid or acid anhydride gp(s). (monomers I), 0.1-80 wt.% (meth)acrylate ester(s) of at least 10C aliphatic alcohols (monomers II), 0-94.9 wt.% "principal monomers", comprising 1-9C alkyl (meth)acrylates, vinyl esters of 1-20C carboxylic acids, up to 20C vinylaromatics, unsatd. nitriles, vinyl halides and/or 2-8C aliphatic hydrocarbons with 1 or 2 double bonds (monomers III) and 0-60 wt.% other monomers (IV). Also claimed is the above process for the prodn. of aq. polymer dispersions.