| 摘要 |
1. A process for the preparation of thermoplastic plasticized polyvinyl butyral molding compositions by acetalization of polyvinyl alcohol with n-butyraldehyde in aqueous phase in the presence of an acid catalyst and, if appropriate, an organic sulfonic acid having an emulsifying action, and aftertreatment of the polyvinyl butyral under acetalization conditions at an elevated temperature in the presence of a compound having an emulsifying action, isolation an/or purification of the polyvinyl butyral 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, which comprises using a polyvinyl alcohol, which contains less than 1% by weight of vinyl acetate units and is capable of association, in the associated state in aqueous flowable solution for the acetalization and performing the acetalization in the presence of 0.1 to 5% by weight, relative to the aqueous phase, of a mineral acid, initially at a temperature below 20 degrees C and later at a temperature from 20 to 70 degrees C, performing the subsequent aftertreatment of the polyvinyl butyral in the presence of an organic sulfonic acid having 8 to 30 carbon atoms and having an emulsifying action, or one of its salts, at 50 to 70 degrees C for 0.5 to 10 hours, and employing as the plasticizer a) an ester of phtalic acid with a linear or branched C6 -C10 -alcohol or mixtures of these alcohols and/or b) an ester of adipic acid with a linear or branched C6 -C10 -alcohol or mixtures of these alcohols in a total quantity of 20 to 40% by weight, relative to the mixture. |
