Multiple-layer polyolefin films
AssigneeImperial Chemical Industries PLC
InventorsCharles R. Nelson, Robert E. Slater
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Abstract
A multiple-layer film comprises an oriented propylene polymer substrate having on opposed surfaces thereof, respectively, a first vinylidene halide copolymer having a Tg of up to 25.degree. C. and a molecular weight not exceeding 135,000 and a second vinylidene halide copolymer having a Tg greater than that of the first copolymer. Such films offer excellent sealing profile, blocking resistance, gas-barrier, humid ageing and printing characteristics.
Claims9
A multiple-layer film comprising a substrate layer of a polyolefin and, on at least one surface thereof, a polymeric heat-sealable layer characterised in that:
- a) the substrate, having opposed first and second surfaces, comprises a layer of an oriented propylene polymer, having
- b) associated with the first surface of the substrate, a layer of a first vinylidene halide copolymer having a glass transition temperature (Tg) of up to 25.degree. C. and a molecular weight (weight average) not exceeding 135,000 and
- c) associated with the second surface of the substrate, a layer of a second vinylidene halide copolymer having a glass transition temperature (Tg) greater than that of the first copolymer.
A method of producing a multi-layer film comprising a substrate layer of a polyolefin and, on at least one surface thereof, a polymeric heat-sealable layer by
- a) forming a substrate comprising a layer of an oriented propylene polymer having opposed first and second surfaces, and providing thereon,
- b) associated with the first surface of the substrate, a layer of a first vinylidene halide copolymer having a glass transition temperature (Tg) of up to 25.degree. C. and a molecular weight (weight average) not exceeding 135,000, and
- c) associated with the second surface of the substrate, a layer of a second vinylidene halide copolymer having a glass transition temperature (Tg) greater than that of the first copolymer.
Dependencies are inferred from the claim text.