LAMINATED PACKAGING FILM HAVING LOW WATER VAPOR AND GAS PERMEABILITY

摘要

1348660 Laminates CONTINENTAL CAN CO Inc 5 Oct 1971 [19 Oct 1970] 46283/71 Headings B5A and B5N A laminated heat sealable film comprises an olefin polymer base layer with a continuous coating of a vinylidene chloride polymer bonded to one surface thereof, a continuous intermediate layer of a first ethylene/vinyl acetate copolymer containing not less than 10% by weight of vinyl acetate bonded to the vinylidene chloride polymer and a top layer of a second ethylene/vinyl acetate copolymer containing not more than 10% vinyl acetate bonded to the intermediate layer. The intermediate layer is extruded between the coated surface of the base layer and the film forming the top layer and laminated thereto in passage between rolls, at least one of which is below the fusion temperature of the ethylene/vinyl acetate copolymer. The base layer may be an ethylene/vinyl acetate copolymer containing between 1 and 10% of vinyl acetate, polyethylene or an oriented polypropylene. The coating may be a vinylidene chloride polymer containing a copolymerizable ethylenically unsaturated monomer and may be applied to the base layer as a solution and dried. The coated base layer is stored on rolls and then unwound, exposed to a jet of air on its uncoated surface before being used to form the laminate, to remove solvent.