Patent US4579696A successfully refreshed from Google Patents.
US4579696A
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Process for making coextruded elastomeric films
Assignee: Bemis Clysar Inc
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Filing: 1984-11-29
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Granted: 1986-04-01
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Expires: 2004-11-29
Abstract
Abstract A transparent, elastomeric, composite film structure having a core ethylene/vinyl acetate copolymer and outer layers of a low density ethylene homopolymer or copolymer with a small amount of another α-olefin or vinyl acetate is made by coextrusion of the polymers in a three-layer combining adapter and quenching on a chill roll. This film structure is useful as a wrapping material, especially for heat-sensitive articles.
Inventors
- 👤 Robert C. Di Luccio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:29
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/32; B32B27/322
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
175 words
A process for making a transparent, elastomeric, composite film structure, wherein an ethylene/vinyl acetate copolymer containing about 30-50 weight percent of vinyl acetate is supplied to the central channel of a three layer combining adapter and a polymer selected from the class consisting of homopolyethylene and copolymers of ethylene with another α-olefin or with vinyl acetate, the comonomer being responsible for up to 10% of the copolymer weight, is supplied to the other two channels, the density of the polymer supplied to the other two channels being at most about 0.94 g/cm 3 , the temperature of the combining adapter being sufficient to maintain each polymer in molten state, and the molten polymers are extruded through said combining adapter and a die to form a molten composite structure containing a core layer and two outer layers, which is solidified by cooling and recovered, the outer layers providing about 0.5-10% of the total thickness of the composite film structure, which structure following coextrusion is exposed to high energy radiation of which it absorbs about 4-16 megarads.
Claim 2
Dependent Claim
175 words
A process for making a transparent, elastomeric, composite film structure, wherein an ethylene/vinyl acetate copolymer containing about 30-50 weight percent of vinyl acetate is supplied to the central channel of a three layer combining adapter and a polymer selected from the class consisting of homopolyethylene and copolymers of ethylene with another α-olefin or with vinyl acetate, the comonomer being responsible for up to 10% of the copolymer weight, is supplied to the other two channels, the density of the polymer supplied to the other two channels being at most about 0.94 g/cm 3 , the temperature of the combining adapter being sufficient to maintain each polymer in molten state, and the molten polymers are extruded through said combining adapter and a die to form a molten composite structure containing a core layer and two outer layers, which is solidified by cooling and recovered, the outer layers providing about 0.5-10% of the total thickness of the composite film structure, which structure following coextrusion is exposed to high energy radiation of which it absorbs about 4-16 megarads.
Claim 3
Dependent Claim
23 words
A process of claim 1 wherein the outer layers provide up to about 6% of the total thickness of the composite film structure.
Claim 4
Dependent Claim
32 words
A process of claim 1, wherein the core ethylene/vinyl acetate copolymer contains about 1-3 weight percent of a long chain aliphatic amide or diamide to improve the composite's slip and block properties.
Claim 5
Dependent Claim
32 words
A process of claim 2, wherein the core ethylene/vinyl acetate copolymer contains about 1-3 weight percent of a long chain aliphatic amide or diamide to improve the composite's slip and block properties.
Claim 6
Dependent Claim
24 words
A process of claim 3 wherein the amide or diamide is selected from the class consisting of stearamide, oleamide, erucamide, palmitamide, ethylenebis(oleamide), and ethylenebis(erucamide).
Claim 7
Dependent Claim
24 words
A process of claim 4 wherein the amide or diamide is selected from the class consisting of stearamide, oleamide, erucamide, palmitamide, ethylenebis(oleamide), and ethylenebis(erucamide).
Claim 8
Dependent Claim
25 words
A process of claim 3 wherein the thickness of at least one outer layer is less than about 1% of the total composite film structure.
Claim 9
Dependent Claim
25 words
A process of claim 4 wherein the thickness of at least one outer layer is less than about 1% of the total composite film structure.
Claim 10
Dependent Claim
20 words
A process of claim 1 wherein the outer layer polymeric material is a linear copolymer of ethylene with an α-olefin.
Claim 11
Dependent Claim
20 words
A process of claim 2 wherein the outer layer polymeric material is a linear copolymer of ethylene with an α-olefin.
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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) | 1989-03-31 | 1989-09-30 | 1990-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-31 | 1993-09-30 | 1994-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-31 | 1997-09-30 | 1998-04-01 | $7700.00 | Window Closed / Lapsed |