Barrier film and process for making

摘要

The present invention is directed toward a film comprising a vinylidene chloride interpolymer, wherein the vinylidene chloride interpolymer having polymerized herein vinylidene chloride in an amount of from about 75 to about 95 percent by weight of interpolymer and from about 25 to about 5 percent by weight of interpolymer of at least one monomer copolymerized therewith, is prepared by extruding said interpolymer through an extrusion die to form an extrudate; passing the extrudate through a cooling means; blowing a blown tubular bubble by expanding the cooled extrudate sheet around a trapped gaseous medium, said bubble having an effective blow-up ratio before deflation such that the bubble after deflation has a desired final blow-up ratio; and conveying the tubular bubble through a deflator means to collapse the bubble into a two-layer film, wherein the film has a final blow-up ratio of between about 2.5 to about 3.5 said film having an amorphous phase and a crystalline phase with vinylidene chloride crystalline units, said crystalline units and amorphous units being positioned such that the film has a machine direction Elmendorf tear strength of at least 1.5 times the transverse direction percent elongation of at least 1.5 times machine direction percent elongation. The film and the process of making the film of the present invention is thought to improve handling of consumer films.