Patent US4923722A successfully refreshed from Google Patents.
US4923722A
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Heat shrinkable composite film and packaging method using same
Assignee: Okura Industrial Co Ltd
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Filing: 1988-03-01
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Granted: 1990-05-08
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Expires: 2008-03-01
Abstract
Abstract A heat shrinkable composite film comprises a core layer formed of (a) a straight chain, low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of the core layer and each formed of (c) a crystalline polypropylene resin having a melting point of 135°-150° C., the core layer having a thickness of 30-80% of the total thickness of the outer layers and the core layer.
Inventors
- 👤 Kazuo Kondo
- 👤 Nobuya Ishiguro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:19
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; B32B27/06; B32B27/08; G; G02; G02B; G02B6/00; G02B6/44; G02B6/4439; G02B6/4471; G02B6/4476; B32B2307/00; B32B2307/70; B32B2307/732; B32B2307/734; B32B2307/736; B32B2323/00; B32B2323/04; B32B2323/046; B32B2323/10; B32B2439/00; B32B2439/40; B32B2439/46; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/13; Y10T428/1328; Y10T428/27; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
101 words
A heat shrinkable composite film comprising as a core at least one of (a) a low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer.
Claim 2
Dependent Claim
101 words
A heat shrinkable composite film comprising as a core at least one of (a) a low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer.
Claim 3
Dependent Claim
22 words
A composite film as claimed in claim 1, wherein said crystalline propylene resin (c) is an ethylene-propylene copolymer or an ethylene-propylene-butene copolymer.
Claim 4
Dependent Claim
41 words
A composite film as claimed in claim 1, and having a shrinking force of not greater than 30 g in both longitudinal and transverse directions at temperatures providing a shrinkage percentage of at least 35% in both longitudinal and transverse directions.
Claim 5
Independent Claim
201 words
A method of packaging an article which comprises the steps of: providing a heat shrinkable composite film which includes a core layer formed of (a) a straight chain, low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer and each formed of (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer, which exhibits a shrinking force of not greater than 30 g in both longitudinal and transverse direct temperatures providing a shrinkage percentage of at least 35% in both longitudinal and transverse directions and which has a size not greater than 1.6 times the exterior surface area of the article; enclosing the article with the film; and heating said enclosure at a temperature so that the film can be shrunken with a shrinkage percentage of at least 35% in both longitudinal and transverse directions.
Claim 6
Independent Claim
201 words
A method of packaging an article which comprises the steps of: providing a heat shrinkable composite film which includes a core layer formed of (a) a straight chain, low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer and each formed of (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer, which exhibits a shrinking force of not greater than 30 g in both longitudinal and transverse direct temperatures providing a shrinkage percentage of at least 35% in both longitudinal and transverse directions and which has a size not greater than 1.6 times the exterior surface area of the article; enclosing the article with the film; and heating said enclosure at a temperature so that the film can be shrunken with a shrinkage percentage of at least 35% in both longitudinal and transverse directions.
Claim 7
Dependent Claim
21 words
A composite film as claimed in claim 1 wherein said core layer comprises a copolymer of ethylene and a higher α-olefin.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-07 | 1993-11-06 | 1994-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-07 | 1997-11-06 | 1998-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-07 | 2001-11-06 | 2002-05-08 | $7700.00 | Window Closed / Lapsed |