Thermoplastic plasticized polyvinylbutyral molding compositions, in particular films of improved tensile strength and reduced tackiness are prepared by acetalization of polyvinyl alcohol, capable of association, in the associated state with n-butyraldehyde in aqueous phase in the presence of an acid catalyst and, if appropriate, of an organic sulfonic acid having an emulsifying action, after-treatment of the polyvinylbutyral under acetalization conditions at an elevated temperature in the presence of an organic sulfonic acid having 8 to 30 C atoms and having an emulsifying action, isolation and/or purification of the polyvinylbutyral and, if appropriate, admixture of conventional additives and mixing of the product, which may have been dried, with up to 40% by weight of plasticizer, relative to the polymer/plasticizer mixture, and molding, the plasticizers employed being esters of phthalic acid with C.sub.6 -C.sub.10 -alcohols and/or esters of adipic acid with C.sub.6 -C.sub.10 -alcohols.Use of the films for the manufacture of laminated glass, and laminated glass containing the films as the joining layer.