Gas barrier film comprising starch, a water soluble polymer, a plasticizer, a fatty acid and an emulsifier

摘要

Disclosed is a polymer composition comprising on a dry basis: a) from 45 to 90% by weight of a modified starch or a starch and a modified starch wherein the modified starch is selected from starches modified by reaction with a hydroxyl alkyl group, an acetate or a dicarboxylic acid anhydride or a grafting polymer; b) from 4 to 12% by weight of a water soluble polymer selected from polyvinyl alcohol, polyvinylacetate, and copolymers of ethylene and vinylalcohol which have a melting point compatible with the molten state of the starch components; c) from 5 to 45% by weight of a non-crystallising mixture of sorbitol and at least one other plasticiser selected from glycerol, maltitol, xylitol, mannitol, glycerol trioleate, epoxidised linseed or soybean oil, tributyl citrate, acetyl tri-ethyl citrate, glyceryl triacetate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate; polyethylene oxide or polyethylene glycol; d) from 0.3 to 2.5% by weight of a fatty acid or salt; e) from 0.25% to 3% of an emulsifier system having a hydrophilic lipophilic balance value between 2 and 10, and wherein the polymer composition is in the form of a gas barrier film. Also disclosed is a co-extruded laminate which comprises polyethylene, polypropylene or polylactic acid and the above composition for thin film packaging applications.