US4515745A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modification of ethylene vinyl acetate copolymer
Assignee: Curwood Inc
•
Filing: 1983-05-18
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Granted: 1985-05-07
•
Expires: 2003-05-18
Abstract
Abstract The melt index is reduced and the rheology is modified in ethylene-vinyl acetate copolymers used in the manufacture of films, by the addition of a crosslinking agent to the copolymer. This allows the use of more readily available raw materials and improves the stability of the bubble during stretching of tubular films.
Inventors
- 👤 Theodore Churma
- 👤 Elwood D. Latimer, Jr.
- 👤 Stephen J. Vicik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:07
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; C08K; C08K5/00; C08K5/04; C08K5/14; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/08
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
79 words
In a process for manufacturing an extruded film having at least one layer of ethylene vinyl acetate copolymer, wherein the copolymer is melted, extruded through a die, and stretched; the improvement comprising the presence of an effective amount sufficient to lower the melt index and modify the rheology of the ethylene vinyl acetate copolymer, and insufficient to crosslink the ethylene vinyl acetate copolymer, of a crosslinking agent in the melted copolymer during extrusion of the ethylene vinyl acetate copolymer.
Claim 2
Dependent Claim
79 words
In a process for manufacturing an extruded film having at least one layer of ethylene vinyl acetate copolymer, wherein the copolymer is melted, extruded through a die, and stretched; the improvement comprising the presence of an effective amount sufficient to lower the melt index and modify the rheology of the ethylene vinyl acetate copolymer, and insufficient to crosslink the ethylene vinyl acetate copolymer, of a crosslinking agent in the melted copolymer during extrusion of the ethylene vinyl acetate copolymer.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein the melt index of the ethylene vinyl acetate copolymer before addition of the crosslinking agent is less than about 0.75.
Claim 4
Dependent Claim
13 words
The process of claim 1 wherein the crosslinking agent is an organic peroxide.
Claim 5
Dependent Claim
11 words
The process of claim 1 wherein the crosslinking agent is 2,5-dimethyl-2,5-bis-(t-butylperoxy)hexane.
Claim 6
Dependent Claim
35 words
The process of claim 4 wherein the crosslinking agent is present in an amount of from about 0.006 to about 0.015 weight percent, based on the combined weight of the copolymer and the crosslinking agent.
Claim 7
Dependent Claim
31 words
The process of claim 5 wherein the crosslinking agent is present in an amount of about 0.00625 weight percent, based on the combined weight of the copolymer and the crosslinking agent.
Claim 8
Dependent Claim
24 words
The process of claim 1, wherein the ethylene vinyl acetate copolymer is melted and extruded at a temperature between 150° C. and 200° C.
Claim 9
Dependent Claim
40 words
The process of claim 1, wherein the crosslinking agent is reactive with the ethylene vinyl acetate copolymer between about 150° C. and 200° C. and essentially unreactive with the ethylene vinyl acetate copolymer between about 93° C. and 107° C.
Claim 10
Dependent Claim
44 words
The process of claim 1 wherein the presence of the crosslinking agent in the copolymer is by a process that comprises providing a concentrate comprising a crosslinking agent dispersed in a polymer compatible with the copolymer, and extruding together the concentrate and the copolymer.
Claim 11
Dependent Claim
23 words
The process of claim 9 wherein the crosslinking agent is dispersed in the polymer by first dissolving the crosslinking agent in a solvent.
Claim 12
Dependent Claim
11 words
The process of claim 10 wherein the solvent is an alcohol.
Claim 13
Dependent Claim
14 words
The process of claim 9 wherein the polymer compatible with the copolymer is polyethylene.
Claim 14
Dependent Claim
20 words
The process of claim 9 wherein the polymer compatible with the copolymer is a copolymer of ethylene and vinyl acetate.
References Cited (Backward Citations)
US2919474A
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US3086966A
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US3968091A
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US3898209A
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US4221699A
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US4171338A
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US4214030A
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US4342844A
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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) | 1988-05-06 | 1988-11-05 | 1989-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-06 | 1992-11-05 | 1993-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-06 | 1996-11-05 | 1997-05-07 | $7700.00 | Window Closed / Lapsed |