Polyvinyl esters with improved melt viscosity behaviour, process for their manufacture and use thereof.

摘要

The preparation of soluble polyvinyl acetals which have a low degree of crosslinking and improved melt-viscosity behaviour by acetalisation of soluble polyvinyl alcohols with a low degree of crosslinking which have been prepared by hydrolysis or alcoholysis of soluble copolymers of vinyl esters and polyethylenically unsaturated monomers, such as, for example, glyoxal bisacrylamide, which copolymers have a low degree of crosslinking. In comparison with comparable uncrosslinked, soluble polyvinyl acetals, polyvinylacetals with a low degree of crosslinking according to the invention have greater structural viscosities and exhibit surprisingly advantageous properties during thermoplastic shaping, in particular during extrusion in plasticised form. The polyvinyl acetals with a low degree of crosslinking furthermore have improved mechanical properties compared with uncrosslinked polyvinyl acetals and are particularly advantageously suitable in plasticised film form for the production of laminated glasses.