Abstract: Polyvinylbutyral of reduced tackiness and improved tensile strength is prepared by acetalization of polyvinyl alcohol, which is capable of association, in the associated state with n-butyraldehyde in aqueous phase in the presence of an acid catalyst. In the process for its preparation from more highly saponified, associated polyvinyl alcohol having a vinyl acetate unit content of less than 1% by weight, the acetalization is started preferably at temperatures below 20.degree. C. and the temperature is raised to above 40.degree. C. in the course of the reaction. Use for the production of plasticized thermoplastic polyvinylbutyral films and use of the latter as the joining layer in laminated glass.

Abstract: The invention relates to finely divided polyvinyl acetal which is prepared in the form of an aqueous suspension or, if desired, in powder form, preferably having average particle sizes from 0.5 to 10 .mu.m, from polyvinyl alcohol and at least one aliphatic aldehyde having at least 3 carbon atoms, and which contains 0.1 to 10% by weight, based on polyvinyl acetal, of a completely or partially hydrolyzed vinyl ester copolymer grafted onto polyethylene oxide or polyethylene oxide derivatives and acetalized in the mixture with the polyvinyl alcohol.The invention further relates to a process for preparing finely divided polyvinyl acetals having an average particle size between 0.5 and 10 .mu.

Abstract: The preparation of polyvinylbutyral is commonly effected by the acetalization of polyvinyl alcohol with n-butyraldehyde, either in an organic solvent or in water. By varying the reaction conditions it is possible to obtain the polyvinylbutyral in a coarse-grain or fine-grained form. The production of polyvinylbutyral having improved properties is possible by using a polyvinylbutyral having a content of from 17 to 24% by weight of vinyl alcohol units as starting material for an after-treatment in the presence of an organic sulfonic acid having an emulsifying effect. The polyvinylbutyral obtained is particularly suitable for the manufacture of compound sheets.