US4277594A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat shrinkable polyethylene film and method for its manufacture
Assignee: Reynolds Metals Co
•
Filing: 1979-05-23
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Granted: 1981-07-07
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Expires: 1999-05-23
Abstract
Abstract Described is a mildly biaxially oriented, blown polyethylene film characterized by a cross directional (CD) shrink force in the range of about 60 to 300 psi, an average heat seal energy of at least about 2.0 in - lbs., an average internal tear resistance of at least about 30 gms/ply, and a minimum shrink temperature no higher than 220° F. and which is less than crystalline melt point (or points) of polyethylene material. This film also has a shrink force in the machine direction (MD) which is typically in the range of about 200 to 300 psi. Also described is the process by which this film is produced.
Inventors
- 👤 Stephen B. Matthews
- 👤 Tomas A. Loredo
- 👤 Walter H. Knox, III
- 👤 Herman F. Simmons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 00:24
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C55/143; C; C08; C08F; C08F110/00; C08F110/02; B29C61/00; B29C61/003; B29C48/00; B29C48/001; B29C48/0018; B29C48/0019; B29C48/03; B29C48/09; B29C48/10; B29K; B29K2023/00; B29K2023/04; B29K2023/06; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31855; Y10T428/31938
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
69 words
A mildly biaxially oriented, blown polyethylene film characterized by a cross directional shrink force in the range of about 60 to 300 psi, an average heat seal energy of at least about 2.0 in-lbs., an average internal tear resistance of at least about 30 gms/ply, and a minimum shrink temperature no higher than 200° F. and which is less than the crystalline melt point (or points) of the polyethylene.
Claim 2
Dependent Claim
69 words
A mildly biaxially oriented, blown polyethylene film characterized by a cross directional shrink force in the range of about 60 to 300 psi, an average heat seal energy of at least about 2.0 in-lbs., an average internal tear resistance of at least about 30 gms/ply, and a minimum shrink temperature no higher than 200° F. and which is less than the crystalline melt point (or points) of the polyethylene.
Claim 3
Dependent Claim
23 words
The film of claim 1 wherein the shrink force in the machine direction is in the range of about 200 to 300 psi.
Claim 4
Dependent Claim
192 words
A process for producing a heat shrinkable biaxially oriented polyethylene film having a CD shrink force between about 60 and 300 psi and a MD shrink force of 200-300 psi, in accordance with a blown bubble method which comprises the sequential steps of (1) extruding as a continuous tube, molten polyethylene which has a crystalline melt point (or points) between about 220° F. and 270° F., (2) expanding the polyethylene tube cross-directionally at a blow ratio between about 3:1 and 8:1, (3) drawing the polyethylene film machine-directionally at a draw ratio between about 1.2:1 and 2.8:1 at a temperature between about 160° F. and 230° F., (4) drawing the polyethylene film cross-directionally at a draw ratio between about 1.2:1 and 2.5:1 at a temperature between about 160° F. and 230° F. but without applying additional heat, (5) relaxing the film so as to allow an MD shrink back between about 0.7:1 and 1.0:1, (6) heating the polyethylene film to a temperature between about 120° F. and 230° F. and (7) then drawing the polyethylene film machine directionally at a ratio between about 1.1:1 and 1.4:1 to achieve the desired finished film properties.
Claim 5
Dependent Claim
192 words
A process for producing a heat shrinkable biaxially oriented polyethylene film having a CD shrink force between about 60 and 300 psi and a MD shrink force of 200-300 psi, in accordance with a blown bubble method which comprises the sequential steps of (1) extruding as a continuous tube, molten polyethylene which has a crystalline melt point (or points) between about 220° F. and 270° F., (2) expanding the polyethylene tube cross-directionally at a blow ratio between about 3:1 and 8:1, (3) drawing the polyethylene film machine-directionally at a draw ratio between about 1.2:1 and 2.8:1 at a temperature between about 160° F. and 230° F., (4) drawing the polyethylene film cross-directionally at a draw ratio between about 1.2:1 and 2.5:1 at a temperature between about 160° F. and 230° F. but without applying additional heat, (5) relaxing the film so as to allow an MD shrink back between about 0.7:1 and 1.0:1, (6) heating the polyethylene film to a temperature between about 120° F. and 230° F. and (7) then drawing the polyethylene film machine directionally at a ratio between about 1.1:1 and 1.4:1 to achieve the desired finished film properties.
Claim 6
Dependent Claim
29 words
A process in accordance with claim 3 wherein the expanded polyethylene tube from step (2) is converted into layflat dimensions for drawing steps (3) through (7) of the process.
References Cited (Backward Citations)
US3361861A
Cited
US2034716A
Cited
US2334022A
Cited
US2412187A
Cited
US2597877A
Cited
US2618012A
Cited
US2582165A
Cited
US3177277A
Cited
US3022543A
Cited
US3144399A
Cited
US3137746A
Cited
US3248753A
Cited
US3091807A
Cited
US3076232A
Cited
US3296351A
Cited
US3248463A
Cited
US3307218A
Cited
US3261903A
Cited
US3383445A
Cited
US3299194A
Cited
US3471606A
Cited
US3231642A
Cited
US3445886A
Cited
US3634553A
Cited
US3548042A
Cited
US3465072A
Cited
US3568252A
Cited
US3494993A
Cited
US3577497A
Cited
US3659000A
Cited
US3676539A
Cited
US3723583A
Cited
US3944644A
Cited
US3891737A
Cited
US3981149A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-06 | 1985-01-05 | 1985-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-06 | 1989-01-05 | 1989-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-06 | 1993-01-05 | 1993-07-07 | $7700.00 | Window Closed / Lapsed |