US4439478A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat sealable, multi-ply polypropylene film
Assignee: Cryovac LLC
•
Filing: 1982-04-15
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Granted: 1984-03-27
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Expires: 2002-04-15
Abstract
Abstract A heat sealable and shrinkable, coextruded, multi-layer packaging film having a propylene homopolymer base layer and a skin layer of a preferred blend of 60% to 80% propylene-ethylene copolymer with propylene homopolymer provides a sealing temperature range of up to 30 DEG C.
Inventors
- 👤 Daniel F. Ferguson
- 👤 Frederick D. Stringer
- 👤 Michael D. Esakov
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:27
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24273; Y10T428/24322; Y10T428/24942; Y10T428/2495; Y10T428/28; Y10T428/2813; Y10T428/2817; Y10T428/2826; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
66 words
A heat-sealable, multi-layer film for packaging comprising: (a) a base layer comprising propylene homopolymer; and, (b) a skin layer affixed to one surface of said base layer comprising a blend of 60% to 80% by weight of film grade, thermoplastic propylene-ethylene copolymer with 40% to 20% by weight of propylene homopolymer, the ratio of thickness of the base layer to skin layer being at least 4:1.
Claim 2
Dependent Claim
66 words
A heat-sealable, multi-layer film for packaging comprising: (a) a base layer comprising propylene homopolymer; and, (b) a skin layer affixed to one surface of said base layer comprising a blend of 60% to 80% by weight of film grade, thermoplastic propylene-ethylene copolymer with 40% to 20% by weight of propylene homopolymer, the ratio of thickness of the base layer to skin layer being at least 4:1.
Claim 3
Dependent Claim
61 words
The heat sealable film of claim 1 wherein said film is heat shrinkable, the ratio of the thickness of the base layer to the skin layer is at least 4:1, and said blend comprises 60% to 80% by weight of propylene-ethylene copolymer with 40% to 20% by weight of propylene homopolymer, said copolymer comprising 2% to 6% by weight of ethylene.
Claim 4
Dependent Claim
19 words
The heat sealable film of claim 1 wherein said film has a sealing range of at least 20° C.
Claim 5
Dependent Claim
12 words
The heat sealable film of claim 1 wherein said film is perforated.
Claim 6
Dependent Claim
24 words
The heat sealable film of claim 1 having a skin layer affixed to both sides of the base layer to structurally balance said film.
Claim 7
Dependent Claim
31 words
The heat sealable film of claim 1 wherein said film will produce a film having a seal strength of at least 300 gms/inch at a temperature as low as 135° C.
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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) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |