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US4497865A
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Polyethylene terephthalate film, process for the production thereof and magnetic recording medium therefrom
Assignee: Toray Industries Inc
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Filing: 1982-09-28
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Granted: 1985-02-05
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Expires: 2002-09-28
Abstract
Abstract The present invention relates to a polyethylene terephthalate film having the sum of F-5 values in longitudinal and transverse directions of 3500 to 5000 kg/cm 2 , absolute heat shrinkages in longitudinal and transverse directions at 100° C. of up to 2.5% and amorphous orientation factor of -1.5 to 0.5, a process for the production thereof and a magnetic recording medium containing the film as a base. The polyethylene terephthalate film useful as a magnetic recording medium having super high-tensile-strength in both longitudinal and transverse directions and a low heat shrinkage is provided, while it has been considered that such properties could not be obtained in polyethylene terephthalate film.
Inventors
- 👤 Satoyuki Minami
- 👤 Kazuhiro Tanaka
- 👤 Takeshi Nishioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:08
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C55/00; B29C55/005; B29C55/02; B29C55/04; B29C55/06; B29C55/065; B29C55/10; B29C55/12; B29C55/14; B29C55/143; B29C55/16; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; B29K; B29K2067/00; C08J2367/00; C08J2367/02; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/91; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
91 words
A magnetic recording medium comprising a polyethylene terephthalate film having the sum of F-5 values in longitudinal and transverse directions of 3500 to 5000 kg/cm 2 , absolute heat shrinkage in longitudinal and transverse directions at 100° C. of up to 2.5% and an amorphous orientation factor of -1.5 to 0.5 and magnetic layer(s) formed on at least one surface of the film, said film being obtained by subjecting a polyethylene terephthalate sheet to multi-stage longitudinal stretching, transverse stretching and biaxial restretching, wherein the total stretching ratio is at least 27.
Claim 2
Dependent Claim
91 words
A magnetic recording medium comprising a polyethylene terephthalate film having the sum of F-5 values in longitudinal and transverse directions of 3500 to 5000 kg/cm 2 , absolute heat shrinkage in longitudinal and transverse directions at 100° C. of up to 2.5% and an amorphous orientation factor of -1.5 to 0.5 and magnetic layer(s) formed on at least one surface of the film, said film being obtained by subjecting a polyethylene terephthalate sheet to multi-stage longitudinal stretching, transverse stretching and biaxial restretching, wherein the total stretching ratio is at least 27.
Claim 3
Dependent Claim
22 words
A magnetic recording medium according to claim 1 wherein the magnetic recording medium is a magnetic recording tape or magnetic recording disc.
Claim 4
Dependent Claim
51 words
A magnetic recording medium according to claim 1 wherein the magnetic layer comprises at least one member of the group consisting of γ-Fe 2 O 3 , Co-doped γ-Fe 2 O 3 , CrO 2 , Fe, Co, Ni and a mixture of at least one of them with a binder.
Claim 5
Dependent Claim
32 words
A magnetic recording medium according to claim 1 wherein the magnetic layer is formed by a method selected from the group consisting of vacuum metallizing, sputtering, ion plating, electroplating and coating methods.
Claim 6
Dependent Claim
19 words
A magnetic recording medium according to claim 1 wherein the magnetic layer has a thickness of 0.05 to 5μ.
Claim 7
Dependent Claim
20 words
A magnetic recording medium according to claim 1 wherein the magnetic recording medium has a thickness of 4 to 9μ.
Claim 8
Dependent Claim
17 words
A magnetic recording medium according to claim 1 wherein the magnetic recording medium is a video tape.
Claim 9
Dependent Claim
17 words
A magnetic recording medium according to claim 1 wherein the magnetic recording medium is a computer tape.
Claim 10
Dependent Claim
17 words
A magnetic recording medium according to claim 1 wherein the magnetic recording medium is an audio tape.
References Cited (Backward Citations)
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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) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |