Barrier film

Abstract

A barrier composition which is injection mouldable and able to be made into a transparent film or incorporated (by co-extrusion and/or lamination) into multi-layer film products, the composition on dry basis: a) from 45 to 90% by weight of a starch and/or a modified starch 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 plasticizer 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 C12-22 fatty acid or salt; e) from 0.25% to 3% of an emulsifier system having a hydrophilic lipophilic balance value between 2 and 10. The barrier film may be co-injection moulded with polyethylene terephthalate (PET) or polylactic acid (PLA) for blow moulding into beverage bottles, with polyethylene (PE) or polypropylene (PP) or biodegradable polymers for high gas-barrier containers or closures, or may be co-extruded with polyethylene, polypropylene or polylactic acid for thin film packaging applications or for blow-moulded containers.