Improvements in or relating to copolymers of vinyl compounds

摘要

Polyvinyl formal and from 5 to 40 per cent by weight (based on the product) of butadiene-acrylonitrile copolymer are heated together. The butadiene-acrylonitrile copolymer may be added during the partial hydrolysis of polyvinyl acetate in a mixture of ethylacetate and ethyl alcohol or in glacial acetic acid and its condensation with formaldehyde in the presence of sulphuric acid. Polyethylene, a polyvinyl ether and polyvinyl pyrrole may also be present. Specification 436,072 is referred to.