Wacker Polymer Systems Gmbh & Co. Kg

Karl-Heinz Eichel

Kurt Stark

Bernhard Glaser

Peter Tschirner

Thomas Kornek

Christian Hoegl

Georg Friedl

Franz Eichberger

Polyvinyl acetals are obtained in a cost-effective and environmentally advantageous manner by employing as at least a portion of the aqueous acetalization medium, the mother liquor from a previous acetalization reaction.

Method for producing polyvinylacetals

Silane-modified polyvinyl acetals are obtained by copolymerizing a) vinyl esters of C alkylcarboxylic acids having from 1 to 15 carbon atoms, and optionally (meth)acrylates C of alcohols, olefins, dienes, vinylaromatics, or vinyl halides, with b) from 0.02 to 20.0 % by weight of an ethylenically unsaturated, hydrolyzable silicon compounds or hydrolyzable mercaptosilanes; hydrolyzing the resulting vinyl ester copolymers to 50 mol % or more of vinyl alcohol units; and acetalizing vinyl alcohol units with a C aliphatic or aromatic aldehydes, wherein from 5 to 50 % by weight of a mixture of comonomers a) and silane comonomers b), based on the total weight of comonomers a) and b), is used as an initial charge, and the remainder is metered in during polymerization, such that the ratio between the comonomers a) and silane comonomers b) remains constant throughout the polymerization, resulting in a homogeneous polymer.

Silane-modified polyvinyl acetals

The invention relates to silane-modified polyvinyl acetals obtained by acetalizing partially hydrolyzed or fully hydrolyzed vinyl ester polymers having at least 50 mol % of vinyl alcohol units with one or more aldehydes, optionally in the form of their hemiacetals or their acetals, where at least one aldehyde contains hydrolyzable silane groups.

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Burghausen, Germany

Karl-Heinz Eichel