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US4617241A
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Linear polyethylene stretch/shrink films
Assignee: Cryovac LLC
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Filing: 1984-01-23
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Granted: 1986-10-14
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Expires: 2004-01-23
Abstract
Abstract A multi-layered thermoplastic polyolefin film having an improved combination of physical characteristics is disclosed. In particular, the multi-layered film evidences an improved combination of elongation, elastic memory, tear resistance and heat shrinkability. Preferred five layer embodiments of the film comprise (1) a core layer of either a low density polyethylene homopolymer or an ethylene vinyl acetate copolymer or a blend of an ethylene vinyl acetate copolymer with a linear low density polyethylene; (2) two adjacent intermediate layers of a linear low density polyethylene and (3) two surface layers of an ethylene vinyl acetate copolymer.
Inventors
- 👤 Walter B. Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:15
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; B32B27/06; B32B27/08; B32B27/16; B32B27/30; B32B27/306; B32B27/322; B32B2250/00; B32B2250/05; B32B2250/24; B32B2250/246; B32B2250/40; B32B2305/00; B32B2305/72; B32B2310/00; B32B2310/08; B32B2310/0875; B32B2310/0887; B32B2323/00; B32B2323/04; B32B2323/046; B32B2331/00; B32B2331/04; Y; Y10; Y10T; Y10T428/00; Y10T428/28; Y10T428/2813; Y10T428/2817; Y10T428/2826; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/31928; Y10T428/31935
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
140 words
In a multilayer, thermoplastic packaging film having a layer of ethylene-vinyl acetate copolymer and a layer of linear low density polyethylene, the improvement wherein: (a) said film comprises at least five layers; (b) the material of the central or core layer is selected from the group consisting of: (1) ethylene-vinyl acetate copolymers, and (2) blends of ethylene-vinyl acetate copolymer with linear low density polyethylene; (c) intermediate layers adjacent each side of the core layer, said intermediate layers consisting essentially a linear low density polyethylene; (d) two surface layers consisting essentially of a copolymer of ethylene-vinyl-acetate; (e) said film having a shrink tension at 205° F. in the transverse and longitudinal directions of approximately 400 p.s.i. or greater; and, (f) said film having an elongation at break at 73° F. in both transverse and longitudinal directions of at least approximately 200%.
Claim 2
Dependent Claim
140 words
In a multilayer, thermoplastic packaging film having a layer of ethylene-vinyl acetate copolymer and a layer of linear low density polyethylene, the improvement wherein: (a) said film comprises at least five layers; (b) the material of the central or core layer is selected from the group consisting of: (1) ethylene-vinyl acetate copolymers, and (2) blends of ethylene-vinyl acetate copolymer with linear low density polyethylene; (c) intermediate layers adjacent each side of the core layer, said intermediate layers consisting essentially a linear low density polyethylene; (d) two surface layers consisting essentially of a copolymer of ethylene-vinyl-acetate; (e) said film having a shrink tension at 205° F. in the transverse and longitudinal directions of approximately 400 p.s.i. or greater; and, (f) said film having an elongation at break at 73° F. in both transverse and longitudinal directions of at least approximately 200%.
Claim 3
Dependent Claim
21 words
The film of claim 1 wherein each layer is cross-linked to the equivalent of a dosage of about 4MR to 8MR.
Claim 4
Dependent Claim
85 words
A multilayer, thermoplastic film consisting of: (a) a core layer consisting essentially of a polymer selected from the group consisting of (i) ethylene-vinyl-acetate copolymers and (ii) blends ethylene-vinyl-acetate copolymers with linear low density polyethylene; (b) two intermediate layers, each intermediate layer being adjacent an opposed side of said core layer and each intermediate layer consisting essentially of linear low density polyethylene; and, (c) two surface layers, each surface layer being adjacent a respective intermediate layer and each surface layer consisting essentially of an ethylene-vinyl-acetate copolymer.
Claim 5
Dependent Claim
85 words
A multilayer, thermoplastic film consisting of: (a) a core layer consisting essentially of a polymer selected from the group consisting of (i) ethylene-vinyl-acetate copolymers and (ii) blends ethylene-vinyl-acetate copolymers with linear low density polyethylene; (b) two intermediate layers, each intermediate layer being adjacent an opposed side of said core layer and each intermediate layer consisting essentially of linear low density polyethylene; and, (c) two surface layers, each surface layer being adjacent a respective intermediate layer and each surface layer consisting essentially of an ethylene-vinyl-acetate copolymer.
Claim 6
Dependent Claim
25 words
The multilayer film of claim 3 wherein the layers of the film have been cross-linked to the equivalent of dosage of about 4MR to 8MR.
Claim 7
Dependent Claim
25 words
The film of claim 3 wherein the ethylene vinyl-acetate copolymer in the core and surface layers has from 8.4% to 9.4% by weight of vinyl-acetate.
Claim 8
Dependent Claim
35 words
The film of claim 5 wherein the core layer consists of blend (ii) and the blend has about 60% by weight of ethylene-vinyl acetate copolymer and about 40% by weight of linear low density polyethylene.
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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) | 1989-10-13 | 1990-04-14 | 1990-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-13 | 1994-04-14 | 1994-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-13 | 1998-04-14 | 1998-10-14 | $7700.00 | Window Closed / Lapsed |