The present invention provides an aqueous polyurethane (PU)-polyacrylate hybrid dispersion obtainable by free radical polymerization of at least one acrylate polymer (A1) in the presence of at least one polyurethane (P1), a process for preparing these aqueous polyurethane-polyacrylate hybrid dispersions, wherein said process comprises a) preparing an aqueous polyurethane dispersion and b) using the polyurethane dispersion thus prepared as raw material for the further synthesis of a polyacrylate dispersion, and the use of the hybrid dispersion thus obtained as binder in filled coating materials, particularly as a binder for flexible roof coatings.