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US 5,702,784 AGranted
Polypropylene heat shrinkable film
AssigneeGunze Limited
InventorsMasayuki Nishimura, Kiyoshi Sogabe, Hiroyuki Tanaka, Shinji Arai
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AssigneeGunze Limited
InventorsMasayuki Nishimura, Kiyoshi Sogabe, Hiroyuki Tanaka, Shinji Arai
Estimating the term…
The heat shrinkable film includes at least one of an ethylene-propylene random copolymer and an ethylene-propylene-butene random copolymer and a propylene-butene copolymer of low crystallinity, which is biaxially stretched simultaneously by a ratio of 2.0-3.5 times for each of the machine direction and the transverse direction by a wet heating method. The film preferably has a tensile elongation at breaking of more than 200%, and a heat shrinking ratio of more than 8% for each of the machine direction and the transverse direction when it is immersed in glycerine at 80.degree. C. for 30 sec. Since the file is excellent in tensile elongation and has satisfactory heat shrinkability at low temperature, it is suitable as a film for use in an automatic L-bar sealer in which a tensile elongation at breaking is an important factor.
A polypropylene heat shrinkable mono-layer film consisting essentially of a blend of propylene-butene copolymer and at least one polymer selected from the group consisting of an ethylene-propylene random copolymer and an ethylene-propylene-butene random polymer, said heat shrinkable film resulting from simultaneous biaxial stretching in a tubular state at a stretching ratio of from 2.0 to 3.5 times in each of the machine direction and the transverse direction under wet heating wherein the tensile elongation at breaking of the film is more than 200%, the tensile modulus of elasticity of the film is less than 9 kg/mm.sup.2 and the film shrinks more than 8% in both the machine and the transverse direction when said film is immersed for 30 seconds in 80.degree. C. glycerine.
Dependencies are inferred from the claim text.