Patent US4226826A successfully refreshed from Google Patents.
US4226826A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacturing polyester films
Assignee: Toray Industries Inc
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Filing: 1979-08-07
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Granted: 1980-10-07
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Expires: 1999-08-07
Abstract
Abstract The present invention relates to a process for preparing a polyester film which has not only uniaxially enhanced mechanical properties but also biaxially enhanced mechanical properties. The process involves heat-setting a biaxially oriented polyester film at a temperature above that used for the machine and transverse direction stretching and above that used for the machine direction re-stretching, but at least 10° C. below the melting point of the polyester, then re-stretching the film in both the machine and transverse directions, and re-heat-setting the film.
Inventors
- 👤 Masahiko Motegi
- 👤 Kazuhiro Tanaka
- 👤 Saburo Fujita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:05
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/10; B29C55/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
129 words
In a process for preparing a polyester film having an F-5 value in the TD which is above 14 kg/mm 2 , the steps which comprise heat-setting a biaxially oriented polyester film obtained by stretching the film at a ratio of more than 2.0 in both the MD and TD, at a temperature above the MD-, TD-, and re-MD stretching temperature but below T m (the melting point of the polyester) -10° C., then restretching the film at a ratio of 1.05-2.5 in MD and then at a ratio of 1.05-2.5 in TD at a temperature between T g (glass transition temperature of the polyester) +10° C. and T m -40° C., and reheat-setting the film at a temperature between T g +50° C. and T m -10° C.
Claim 2
Dependent Claim
129 words
In a process for preparing a polyester film having an F-5 value in the TD which is above 14 kg/mm 2 , the steps which comprise heat-setting a biaxially oriented polyester film obtained by stretching the film at a ratio of more than 2.0 in both the MD and TD, at a temperature above the MD-, TD-, and re-MD stretching temperature but below T m (the melting point of the polyester) -10° C., then restretching the film at a ratio of 1.05-2.5 in MD and then at a ratio of 1.05-2.5 in TD at a temperature between T g (glass transition temperature of the polyester) +10° C. and T m -40° C., and reheat-setting the film at a temperature between T g +50° C. and T m -10° C.
Claim 3
Dependent Claim
58 words
A process as recited in claim 1, in which the biaxially oriented polyester film is obtained by stretching the substantially amorphous polyester sheet 2.0-6.0 times in one direction at a temperature between T g and T g +60° C., and then 2.0-6.0 times in the perpendicular direction at a temperature between T g and T g +80° C.
Claim 4
Dependent Claim
42 words
A process as recited in claim 1, in which the biaxially oriented polyester film is obtained by stretching the substantially amorphous polyester sheet in both MD and TD simultaneously 2.0-5.0 times at a temperature between T g and T g +80° C.
Claim 5
Dependent Claim
30 words
A process as recited in claim 1, in which the product of the first stretching ratio and the second stretching ratio are more than 4.0 in both MD and TD.
Claim 6
Dependent Claim
17 words
A process as recited in claim 1, in which the re-TD-stretching temperature is above the re-MD-stretching temperature.
Claim 7
Dependent Claim
16 words
A process as recited in claim 1, in which the polyester is polyethylene terephthalate or polyethylene-2,6-naphthalate.
Claim 8
Dependent Claim
17 words
A process as recited in claim 6, in which the intrinsic viscosity of the polyester is 0.5-1.0.
Claim 9
Dependent Claim
37 words
A process as recited in claim 1, which further contains a step of heat-setting of the re-MD-stretched film before the re-TD-stretching process at a temperature above re-MD- and re-TD stretching temperature but below T m -10° C.
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) | 1983-10-07 | 1984-04-07 | 1984-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-07 | 1988-04-07 | 1988-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-07 | 1992-04-07 | 1992-10-07 | $7700.00 | Window Closed / Lapsed |