US4352849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coextruded, heat-shrinkable, multi-layer, polyolefin packaging film
Assignee: Cryovac LLC
•
Filing: 1981-03-26
•
Granted: 1982-10-05
•
Expires: 2001-03-26
Abstract
Abstract The multi-layer polyolefin shrink film of this invention provides a unique combination of shrink tension, optical clarity, cuttability, sealability, shrink temperature range, and tear resistance which is highly desirable for many packaging applications. The preferred film has three layers in which the core layer comprises an ethylene-vinyl acetate copolymer blended with an ethylene-propylene copolymer and each surface layer comprises an ethylene-propylene copolymer.
Inventors
- 👤 Walter B. Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:41
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; B29; B29C; B29C61/00; B29C61/06; B29C61/0608; B29C61/0616; B32B17/00; B32B17/06; B32B17/10; B32B17/10005; B32B17/1055; B32B17/10788; B32B27/06; B32B27/08; B32B2307/00; B32B2307/40; B32B2307/412; B32B2307/50; B32B2307/582; B32B2307/5825; B32B2307/70; B32B2307/732; B32B2307/734; B32B2307/736; B32B2553/00; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/31928
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
90 words
A multilayer, heat shrinkable packaging film comprising: (a) a core layer consisting essentially of from 5% to 50% by weight of an ethylene-propylene copolymer blended with 95% to 50% by weight of an ethylene-vinyl acetate copolymer wherein the vinyl acetate content of the ethylene-vinyl acetate copolymer is in the range of 4% to 18%; and (b) skin or surface layers comprising an ethylene-propylene copolymer, wherein the ethylene content of the ethylene-propylene copolymer in the core blend and the surface layer is in the range of 1% to 6% by weight.
Claim 2
Dependent Claim
90 words
A multilayer, heat shrinkable packaging film comprising: (a) a core layer consisting essentially of from 5% to 50% by weight of an ethylene-propylene copolymer blended with 95% to 50% by weight of an ethylene-vinyl acetate copolymer wherein the vinyl acetate content of the ethylene-vinyl acetate copolymer is in the range of 4% to 18%; and (b) skin or surface layers comprising an ethylene-propylene copolymer, wherein the ethylene content of the ethylene-propylene copolymer in the core blend and the surface layer is in the range of 1% to 6% by weight.
Claim 3
Dependent Claim
17 words
The film of claim 1 wherein said layers are melt joined without an adhesive material interposed therebetween.
Claim 4
Dependent Claim
23 words
The film of claim 1 wherein the thickness of the core material comprises 80% to 30% of the total thickness of the film.
Claim 5
Dependent Claim
72 words
The film of claim 1 wherein: (i) the core layer comprises about 60% of the total film thickness; (ii) the vinyl acetate content of the ethylene-vinyl acetate copolymer is approximately 12% by weight; (iii) the ethylene content of the ethylene-propylene copolymer is 2.7% to 4% by weight; (iv) the ethylene-vinyl acetate content of the core layer is about 90% by weight; and (v) the layers are melt joined without adhesive interposed therebetween.
Claim 6
Dependent Claim
19 words
The film of claim 4 wherein the skin layers are biaxially oriented and the core layer is substantially unoriented.
Claim 7
Dependent Claim
15 words
The film of claim 4 wherein the shrink tension range is 215 to 285 p.s.i.
Claim 8
Dependent Claim
24 words
The film of claim 1 wherein the ethylene content of the ethylene-propylene copolymer in the core is the same as in the skin layers.
Claim 9
Dependent Claim
30 words
The film of claim 1 wherein the ethylene content of the ethylene-propylene copolymer in the core is higher than the ethylene content of the ethylene-propylene copolymer in the skin layers.
References Cited (Backward Citations)
US4277578A
Cited
US4194039A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-04 | 1986-04-05 | 1986-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-04 | 1990-04-05 | 1990-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-04 | 1994-04-05 | 1994-10-05 | $7700.00 | Window Closed / Lapsed |