Peelable thermoplastic film

Abstract

Heat-sealable thermoplastic elastomeric films comprise from approximately 35% to about 65% of an A-B-A block copolymer wherein "A" blocks are derived from polystrene or a polystrene homolog and said "B" blocks being derived from lower alkenes and from about 25% to about 55% of an ethylene vinyl acetate copolymer, the ethylene vinyl acetate copolymer comprising approximately 28% vinyl acetate. The films are heat-sealable to various substrates including polyvinyl chloride. Once sealed to the substrate, the film may be readily peeled from the substrate by the application of a low and relatively constant peel force. A method for measuring the peel strengths of the film is disclosed. The films are especially adapted to being heat-sealed to a substrate which forms, together with the substrate a package, or multiple serially connected packages. Since the films may be peeled from such a substrate by the application of a low and relatively constant peel force, the films may be peeled from the substrate and the packaged articles extracted from the compartments in a controlled manner. Shear forces generated by flexing or winding the substrate are absorbed by the films without affecting the seal formed with the substrate.

Dependencies are inferred from the claim text.