GB575626A - Improvements in or relating to the production of polyvinyl ethers - Google Patents

Abstract

A polyvinyl cyanoethyl ether is made by reacting a solid polyvinyl compound having a plurality of -CH2-CH (OH)- groups with vinyl cyanide in the liquid phase in the presence of a water-soluble alkali and water. The amount of alkali is 0.01 per cent to 10 per cent and the water 1 per cent to 50 per cent of the polyvinyl compound. Alkalis specified are sodium and barium hydroxides, quaternary ammonium bases, alkali metal cyanides, carbonates and acetates. A solvent for the product, e.g. excess of vinyl cyanide, acetone, methyl acetate or dioxane may be present. The degree of conversion may be regulated by stopping the reaction by addition of hydrochloric, sulphuric or acetic acids or zinc or ammonium chloride, or by using the calculated amount of vinyl cyanide. Suitable polyvinyl compounds are polyvinyl alcohol, partially hydrolysed polyvinyl acetate, partial ethers of polyvinyl alcohol, partial acetals, hydrolysed copolymers of vinyl esters with acrylic acids and their esters, nitriles, amides and imides, styrene, vinyl halides or other esters. The product may be recovered by evaporation of the solvent or by precipitation with a non-solvent, e.g. aqueous alcohol. It may contain from 20 per cent to 100 per cent of converted hydroxyl groups. The ethers may be used as adhesives alone or admixed with plasticisers, solvents or other adhesives. Films cast from acetone solution may be used as pressure sensitive adhesives. French Specification 830,863 is referred to.