Process for making terpolymers of vinyl chloride, vinyl acetate, and vinyl alcohol

A terpolymer containing 40-93% of vinyl alcohol and the remainder vinyl acetate is obtained by reacting vinyl chloride and vinyl acetate in proportions to yield a vinyl chloride-vinyl acetate copolymer resin containing between 7 and 60% of vinyl acetate, in solution in the presence of a polymerization catalyst, stripping unreacted monomers from the resultant resin solution, heating the stripped solution of the resin with an alkaline alcoholysis catalyst and precipitating and recovering from the resin solution the required terpolymer. The solvent is preferably a lower alkoxyalkanol such as methoxyethanol, ethoxyethanol, p methoxy isopropanol, or a mixture of ethoxyethanol with dioxane or methoxyethyl acetate. The polymerization catalyst may be diacetyl peroxide in an amount not exceeding 0.30% by weight. The alcoholysis catalyst may be an alkali metal methylate or an alkali metal 2-methoxyethylate and the heating with the catalyst may be effected at 20-60 DEG C. The resultant dilute solution may be bleached by bubbling chlorine through. The terpolymer is then precipitated using a 65-80% solution of the lower alkoxy ethanol containing solvent in water as thex precipitant, and is washed, centrifuged with further washing and flash dried.