METHOD FOR PRODUCING POLYVINYLACETALS

摘要

A process for preparation of polyvinyl acetals (PVA) obtainable by saponification of a vinylester polymerisate and final acetalization of the polyvinyl alcohol obtained with one or more aldehydes where:the PVA is in aqueous medium, the pH is adjusted to less than 1, acetalization is achieved by addition of aldehyde, the precipitated PVA is filtered off, and a filtrate from a previous deposit is used as aqueous medium is new. A process for preparation of polyvinyl acetals (PVA) obtainable by saponification of a vinylester polymerisate (VEP) and final acetalization of the polyvinyl alcohol obtained with one or more aldehydes selected from 1-15C aliphatic and aromatic aldehdyes, where:(a) the PVA is in aqueous medium, ( b) optionally a pH of less than 1 is established by acid addition, (c) acetalization is achieved by addition of aldehyde component, and (d) separation of the precipitated PVA by filtration, and use of a filtrate from a previous deposit containing 10-100 wt.% of filtrate as aqueous medium.