Abstract: Polymers with polyvinyl acetal groups, which contain acetalized polyvinyl alcohol groups on polyurethane grafting substrates and which are prepared from graft polymers, containing vinyl alcohol groups on polyurethane grafting substrates, by reaction with aldehydes according to known methods. The aldehydes used can be any known aldehydes capable of acetalization reactions.The polyurethane grafting substrates contain at least 2 urethane groups in the molecule and units from diisocyanates and diols, and polymer radicals of units of vinyl carboxylates having 3 to 20 carbon atoms and/or hydrolysis products thereof and, if appropriate, further monomer units are grafted onto the polyurethane grafting subtrates. The proportion of vinyl alcohol units in the hydrolyzed or partially hydrolyzed graft polymers before the acetalization is >10% by weight.In the acetalized polymer, the content of residual unacetalized vinyl alcohol units is >7.

Abstract: Polymers with polyvinyl acetal groups, which contain acetalized polyvinyl alcohol groups on polyurethane grafting substrates and which are prepared from graft polymers, containing vinyl alcohol groups on polyurethane grafting substrates, by reaction with aldehydes according to known methods. The aldehydes used can be any known aldehydes capable of acetalization reactions.The polyurethane grafting substrates contain at least 2 urethane groups in the molecule and units from diisocyanates and diols, and polymer radicals of units of vinyl carboxylates having 3 to 20 carbon atoms and/or hydrolysis products thereof and, if appropriate, further monomer units are grafted onto the polyurethane grafting substrates. The proportion of vinyl alcohol units in the hydrolyzed or partially hydrolyzed graft polymers before the acetalization is >10% by weight.In the acetalized polymer, the content of residual unacetalized vinyl alcohol units is >7.

Abstract: 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.

Abstract: Mixtures of two distinct polyvinyl butyral grades, viz., one high viscosity and one low viscosity grade, both having a narrow molecular weight distribution exhibit good processing characteristics which nearly reach the performance of the high viscosity grades hitherto used.