Plasticized polyvinyl alcohol compositions, forming process and formed articles

Claim 1

A process for the manufacture of a formed article of polyvinyl alcohol, said article having an oxygen permeability no greater than about 1 cc. mil/100 in. 2 day atm. at 25° C. and 80% relative humidity, consisting essentially of: 1. mixing a. A polyvinyl alcohol homopolymer having a vinyl alcohol content in excess of 95%; or b. a blend of (a) with a polyvinyl alcohol/C 2-4 olefin copolymer wherein (a) is at least 25% by weight of the mixture and the olefin moiety in the copolymer is not more than about 45% by weight of the copolymer; with c. a plasticizer selected from the group consisting of N-substituted C fatty acid amides; aryl, alkaryl, N-aryl aryl, N-alkaryl aryl and N-alkyl alkaryl sulfonamides and alkaryl sulfonamides; N-alkyl pyrrolidones; sulfonated alkyl phenols; aryl and alkaryl phosphates and phosphites; alkylene carbonates and selected mixtures thereof; 2. removing the water from the mixture so that it is essentially anhydrous and forming the dry mixture into an article; 3. heating the article to a temperature of at least about 200° C., either concurrently with or after the forming step 2; and 4. slowly cooling the resulting article.