US4675364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modification of ethylene vinyl acetate copolymer
Assignee: Viskase Corp
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Filing: 1985-02-13
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Granted: 1987-06-23
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Expires: 2005-02-13
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
2026-11-05 10:27
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: 2
Claim 1
Independent Claim
116 words
An extrudable mixture for manufacturing of extruded film having at least one layer of eithylene vinyl acetate copolymer, wherein the copolymer is melted, extruded through an annular die to form a tube, and stretched by radially expanding the tube by forming a bubble in the tube by gas inflation; which mixture comprisess a melted ethylene vinyl acetate copolymer having a melt index less than about 0.75, and a effective amount of 2.5-dimethyl-2,5-bis-t-butylperoxy hexane sufficent to lower the melt index of the mixture to less than about 0.4 and to modify the rheology of the ethylene vinyl acetate copolymer so as to improve the stability of the bubble, and insufficent to crosslink the ethylene vinyl acetate copolymer.
Claim 2
Dependent Claim
116 words
An extrudable mixture for manufacturing of extruded film having at least one layer of eithylene vinyl acetate copolymer, wherein the copolymer is melted, extruded through an annular die to form a tube, and stretched by radially expanding the tube by forming a bubble in the tube by gas inflation; which mixture comprisess a melted ethylene vinyl acetate copolymer having a melt index less than about 0.75, and a effective amount of 2.5-dimethyl-2,5-bis-t-butylperoxy hexane sufficent to lower the melt index of the mixture to less than about 0.4 and to modify the rheology of the ethylene vinyl acetate copolymer so as to improve the stability of the bubble, and insufficent to crosslink the ethylene vinyl acetate copolymer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |