US3903294A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of forming heat shrinkable polyethylene terephalate film
Assignee: Celanese Corp
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Filing: 1973-09-13
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Granted: 1975-09-02
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Expires: 1993-09-13
Abstract
Abstract A biaxially oriented polyethylene terephthalate film having balanced shrinkage of at least 40 percent in both longitudinal and transverse directions and the process for forming the film. The biaxially oriented polyethylene terephthalate film is formed in a process where a cast sheet of polyethylene terephthalate is stretched in a first and a second direction, the second direction being perpendicular to the first direction. The ratio of the degree of stretching in the first and second directions is in the range of between about 0.8 and 1.2. The biaxially stretched film is thereafter heat set at a temperature in the range of between about 40*and 80*C.
Inventors
- 👤 Richard M Abella
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:21
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C71/00; B29K; B29K2067/00; B29K2995/00; B29K2995/0037; B29K2995/0049
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
159 words
A PROCESS FOR FORMING BIAXIALLY ORIENTED, HEAT SHRINK ABLE FILM HAVING BALANCED PROPERTIES WHICH COMPRISES STRETCHING A CAST SHEET OF POLYETHYLENE TERESPHTHALATE IN A FIRST DIRECTIN, SAID CAST SHEET STRETCHED AT A DRAW RATIO IN THE RANGE OF BETWEEN ABOUT 2.5:1 AND 3.5:1 AND AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 65* AND 75*C., TO FORM A UNIAXIALLY DRAWN SHEET, THEREAFTER STRECHING SAID UNIAXIALLY DRAWN SHEET IN SECOND DIRECTION, PERPENDICULAR TO THE FIRST DIRECTION, SAID UNIAXIALLY DRAWN SHEET STRETCHED AT A DRAW RATO IN THE RANGE OF BETWEEN ABOUT 2.5:1 AND 3.5:1 AND AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 70* AND 85*C, TO FORM A POLYETHYLENE TERESPHTHALATE FILM, THE RATIO OF THE DEGREE OF STRECTHING IN SA ID FIRST DIRECTION TO THE DEGREE IN SAID SECOND DIRECTION BEING IN THE RANGE OF BETWEEN ABOUT 0.8 AND 1.2, SAID FILM THEREAFTER HEAT SET AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 40* AND 80*C.
Claim 2
Dependent Claim
159 words
A PROCESS FOR FORMING BIAXIALLY ORIENTED, HEAT SHRINK ABLE FILM HAVING BALANCED PROPERTIES WHICH COMPRISES STRETCHING A CAST SHEET OF POLYETHYLENE TERESPHTHALATE IN A FIRST DIRECTIN, SAID CAST SHEET STRETCHED AT A DRAW RATIO IN THE RANGE OF BETWEEN ABOUT 2.5:1 AND 3.5:1 AND AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 65* AND 75*C., TO FORM A UNIAXIALLY DRAWN SHEET, THEREAFTER STRECHING SAID UNIAXIALLY DRAWN SHEET IN SECOND DIRECTION, PERPENDICULAR TO THE FIRST DIRECTION, SAID UNIAXIALLY DRAWN SHEET STRETCHED AT A DRAW RATO IN THE RANGE OF BETWEEN ABOUT 2.5:1 AND 3.5:1 AND AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 70* AND 85*C, TO FORM A POLYETHYLENE TERESPHTHALATE FILM, THE RATIO OF THE DEGREE OF STRECTHING IN SA ID FIRST DIRECTION TO THE DEGREE IN SAID SECOND DIRECTION BEING IN THE RANGE OF BETWEEN ABOUT 0.8 AND 1.2, SAID FILM THEREAFTER HEAT SET AT A TEMPERATURE IN THE RANGE OF BETWEEN ABOUT 40* AND 80*C.
Claim 3
Dependent Claim
37 words
A process in accordance with claim 1 wherein said ratio of the degree stretching in said first direction to the degree of stretching in said second direction is in the range of between about 0.9 and 1.1.
Claim 4
Dependent Claim
23 words
A process in accordance with claim 1 wherein said first direction is the longitudinal direction and said second direction is the transverse direction.
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) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |