Patent ID: 6821590
Filing Date: 2004-11-23
Classification: B65D,C08J,C08K,C08L,Y02W,Y10T

Abstract:
A method for preparing a water-soluble copolymer film for packaging of a non-liquid product, the method comprising the steps of:providing a vinyl acetate-methyl acrylate copolymer; hydrolyzing the vinyl acetate-methyl acrylate copolymer to form a vinyl alcohol-gamma lactone copolymer having a 4% solution viscosity in the range of from about 5 to about 50 cps at 20Â° C.; slurrying the hydrolyzed polymer with water; adding modified starch to the copolymer-water slurry in an amount of from about 8.0 to about 25.0 percent by weight; heating the vinyl alcohol-gamma lactone copolymer and starch to form a solution; treating the solution with caustic soda to create a solution of a copolymer having from about 1 to about 12 mol percent carboxylate groups, from about 0 to about 11 mol percent gamma lactone units, and from about 88 to 99 mol percent vinyl alcohol units; and casting the hot copolymer solution on a suitable surface to create a film having a thickness in the range of from about 0.1 to about 5.0 mils (about 0.0025 to about 0.127 mm).