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US 4,391,862 AGranted
Pasteurizable thermoplastic film and receptacle therefrom
AssigneeW. R. Grace & Co., Cryovac Division
InventorsNorman D. Bornstein, Johnnie J. Walters
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AssigneeW. R. Grace & Co., Cryovac Division
InventorsNorman D. Bornstein, Johnnie J. Walters
Estimating the term…
Disclosed is a multi-layer, heat shrinkable, thermoplastic packaging film which can be heat sealed to itself to provide strong seals at pasteurizing temperatures. The preferred film has four layers including, in order, a sealing surface layer comprising a blend of propylene-ethylene copolymer and (butene-1)-ethylene copolymer, a layer comprising ethylene-vinyl acetate copolymer which may be cross-linked to further increase high temperature strength of the film as desired; a relatively gas impermeable layer comprising a copolymer of vinylidene chloride; and, a surface layer of the same blend as the sealing layer. Receptacles such as end seal and side seal bags can be made from the film at a faster rate than with prior art films and these receptacles have the high temperature seal qualities of propylene polymers and the hot water shrink capabilities of ethylene polymers.
A multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat selas having improved seal strength immediately after initially being heat sealed to itself comprising:
A process for making a multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat seals having improved seal strength immediately after being heat sealed to itself comprising the steps of:
Dependencies are inferred from the claim text.