US4504434A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and polymer blend composition for stretch wrap film
Assignee: Amcor Flexibles North America Inc
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Filing: 1982-12-01
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Granted: 1985-03-12
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Expires: 2002-12-01
Abstract
Abstract A composition adapted for processing into stretch wrap film. The composition comprises between about 40 and about 90% by weight of a high molecular weight copolymer of ethylene and vinyl acetate containing between about 4 and about 25% by weight of repeating units derived from vinyl acetate and having a melt index of between about 0.1 and about 4.0. The composition further comprises between about 8 and about 55% by weight of a linear copolymer of ethylene and a higher alkene. Such linear copolymer has a specific gravity of between about 0.917 and about 0.945. The invention further includes stretch wrap film, a method of producing stretch wrap film of differential cling properties, and a composite film constituted of a layer of the aforesaid ethylene vinyl acetate copolymer and a layer of the linear copolymer of ethylene and a higher alkene.
Inventors
- 👤 Barry A. Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:55
CPC Classifications
C; C08; C08L; C08L23/00; C08L23/02; C08L23/04; C08L23/08; C08L23/0807; C08L23/0815; B; B32; B32B; B32B27/00; B32B27/32; C08J; C08J5/00; C08J5/18; C08L23/0846; C08L23/0853; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/08; C08L2205/00; C08L2205/03; C08L23/18; C08L23/20; C08L23/22
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
137 words
A method for producing a film adapted for use in stretch wrap packaging comprising the steps of: preparing a polymer blend comprising: between about 40 and about 90% by weight of a high molecular weight copolymer of ethylene and vinyl acetate containing between about 4 and about 25% by weight of repeating units derived from vinyl acetate and having a melt index of between about 0.1 and about 4.0, between about 8 and about 55% by weight of a linear copolymer of ethylene and a higher alkene, said linear copolymer having a specific gravity of between about 0.917 and about 0.945, and between about 0.5 and about 6% by weight of a tackifier selected from a group consisting of low molecular weight polyisobutene, amorphous polypropylene, and microcrystralline wax; and extruding said blend to produce a plastic film.
Claim 2
Independent Claim
137 words
A method for producing a film adapted for use in stretch wrap packaging comprising the steps of: preparing a polymer blend comprising: between about 40 and about 90% by weight of a high molecular weight copolymer of ethylene and vinyl acetate containing between about 4 and about 25% by weight of repeating units derived from vinyl acetate and having a melt index of between about 0.1 and about 4.0, between about 8 and about 55% by weight of a linear copolymer of ethylene and a higher alkene, said linear copolymer having a specific gravity of between about 0.917 and about 0.945, and between about 0.5 and about 6% by weight of a tackifier selected from a group consisting of low molecular weight polyisobutene, amorphous polypropylene, and microcrystralline wax; and extruding said blend to produce a plastic film.
Claim 3
Dependent Claim
16 words
A method as set forth in claim 1 wherein said tackifier comprises low molecular weight polyisobutene.
Claim 4
Dependent Claim
31 words
A method as set forth in claim 2 wherein said blend further comprises between about 0.25% and about 3.0% by weight of a monoester of a fatty acid and a polyol.
Claim 5
Dependent Claim
25 words
A method as set forth in claim 3 wherein said ester is selected from the group consisting of esters of sorbitan and ester of glycerol.
Claim 6
Dependent Claim
14 words
A method as set forth in claim 4 wherein said ester comprises glycerol monooleate.
Claim 7
Dependent Claim
22 words
A method as set forth in claim 2 further comprising passing one side only of the film through a corona discharge zone.
Claim 8
Dependent Claim
32 words
A method as set forth in claim 1 wherein said blend further comprises between about 0.25 percent and 3.0 percent by weight of a monoester of a fatty acid and a polyol.
Claim 9
Dependent Claim
25 words
A method as set forth in claim 7 wherein said ester is selected from the group consisting of esters of sorbitan and esters of glycerol.
Claim 10
Dependent Claim
14 words
A method as set forth in claim 8 wherein said monoester comprises glycerol monooleate.
Claim 11
Dependent Claim
22 words
A method as set forth in claim 7 further comprising passing one side only of the film through a corona discharge zone.
Claim 12
Dependent Claim
22 words
A method as set forth in claim 1 further comprising passing one side only of the film through a corona discharge zone.
Claim 13
Independent Claim
123 words
A method for producing a film adapted for use in stretch wrap packaging comprising the steps of: preparing a polymer blend comprising: a high molecular weight copolymer of ethylene and vinyl acetate containing between about 4 and about 25% by weight of repeating units derived from vinyl acetate and having a melt index of between about 0.1 and about 4.0, and a linear low density polyethylene comprising a copolymer of ethylene and a higher alkene, said linear copolymer having a specific gravity of between about 0.917 and about 0.945, and polyisobutene as a tackifier, the proportions of the components of said blend being adapted to provide a film having stretch wrap and cling properties; and extruding said blend to produce a plastic film.
Claim 14
Independent Claim
123 words
A method for producing a film adapted for use in stretch wrap packaging comprising the steps of: preparing a polymer blend comprising: a high molecular weight copolymer of ethylene and vinyl acetate containing between about 4 and about 25% by weight of repeating units derived from vinyl acetate and having a melt index of between about 0.1 and about 4.0, and a linear low density polyethylene comprising a copolymer of ethylene and a higher alkene, said linear copolymer having a specific gravity of between about 0.917 and about 0.945, and polyisobutene as a tackifier, the proportions of the components of said blend being adapted to provide a film having stretch wrap and cling properties; and extruding said blend to produce a plastic film.
Claim 15
Dependent Claim
22 words
A method as set forth in claim 12 wherein said blend further comprises a monoester of a fatty acid and a polyol.
Claim 16
Dependent Claim
25 words
A method as set forth in claim 13 wherein said ester is selected from the group consisting of esters of sorbitan and esters of glycerol.
Claim 17
Dependent Claim
22 words
A method as set forth in claim 13 further comprising passing one side only of the film through a corona discharge zone.
Claim 18
Dependent Claim
14 words
A method as set forth in claim 14 wherein said monoester comprises glycerol monooleate.
Claim 19
Dependent Claim
21 words
A method as set forth in claim 13 further comprising one side only of the film through a corona discharge zone.
Claim 20
Dependent Claim
22 words
A method as set forth in claim 12 further comprising passing one side only of the film through a corona discharge zone.
Claim 21
Dependent Claim
37 words
A method as set forth in claim 18 wherein, after passing the film through said zone, the side of the film not subjected to corona discharge exhibits greater cling properties than the side passed through said zone.
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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) | 1988-03-11 | 1988-09-10 | 1989-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-11 | 1992-09-10 | 1993-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-11 | 1996-09-10 | 1997-03-12 | $7700.00 | Window Closed / Lapsed |