Patent US4673612A successfully refreshed from Google Patents.
US4673612A
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Magnetic recording medium
Assignee: Canon Inc
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Filing: 1985-12-27
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Granted: 1987-06-16
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Expires: 2005-12-27
Abstract
Abstract A magnetic recording medium, comprising an aromatic polyimide film and a magnetic layer of a ferromagnetic material provided on the aromatic polyimide film. The aromatic polyimide film is prepared by imidation of a film formed from a solution of a polyamic acid solution obtained by copolymerization of an aromatic amine component comprising at least 30 mole % of p-phenylene diamine and 0 to 70 mole % of diaminodiphenylether, respectively based on the total amount of the aromatic amine component, and a tetracarboxylic acid dianhydride.
Inventors
- 👤 Hiroshi Takagi
- 👤 Akira Shinmi
- 👤 Kenji Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:18
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7373; G11B5/739; G11B5/73923; G11B5/73937; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31721
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
98 words
A magnetic recording medium comprising an aromatic polyimide film and a magnetic layer of a ferromagnetic metal provided on said aromatic polyamide film; said aromatic polyimide film being prepared by imidation of a film formed from a solution of an aromatic polyamic acid which has been obtained by copolymerization of aromatic diamine components comprising 40-95 mole % of a p-phenylenediamine and 5-60 mole % of diaminodiphenyl ether, respectively based on the total amount of the aromatic diamine components, and tetracarboxylic acid components comprising 15-85 mole % of biphenyltetracarboxylic acid dianhydride and 15-85 mole % of pyromellitic acid dianhydride.
Claim 2
Dependent Claim
98 words
A magnetic recording medium comprising an aromatic polyimide film and a magnetic layer of a ferromagnetic metal provided on said aromatic polyamide film; said aromatic polyimide film being prepared by imidation of a film formed from a solution of an aromatic polyamic acid which has been obtained by copolymerization of aromatic diamine components comprising 40-95 mole % of a p-phenylenediamine and 5-60 mole % of diaminodiphenyl ether, respectively based on the total amount of the aromatic diamine components, and tetracarboxylic acid components comprising 15-85 mole % of biphenyltetracarboxylic acid dianhydride and 15-85 mole % of pyromellitic acid dianhydride.
Claim 3
Dependent Claim
21 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is a Co layer formed by oblique vapor deposition.
Claim 4
Dependent Claim
29 words
A magnetic recording medium according to claim 1, wherein said aromatic diamine component comprises 45 to 90 mole % of p-phenylenediamine and 10 to 55 mole % of diaminodiphenylether.
Claim 5
Dependent Claim
16 words
A magnetic recording medium according to claim 1, wherein said magnetic layer comprises a Co-Cr alloy.
Claim 6
Dependent Claim
28 words
A magnetic recording medium according to claim 4, wherein said magnetic layer of a Co-Cr alloy is formed on said aromatic polyimide film through a Fe-Ni alloy layer.
Claim 7
Dependent Claim
21 words
A magnetic recording medium according to claim 1, wherein said aromatic polyimide film layer has a thickness of 50μ or less.
Claim 8
Dependent Claim
21 words
A magnetic recording medium according to claim 6, wherein said aromatic polyimide film layer has a thickness of 10μ or less.
Claim 9
Dependent Claim
19 words
A magnetic recording medium according to claim 1, wherein said magnetic layer has a thickness of 0.1 to 1.0μ.
Claim 10
Dependent Claim
21 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is provided directly on said aromatic polyimide film layer.
Claim 11
Dependent Claim
25 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is provided through an intermediary non-magnetic film on said aromatic polyimide film layer.
Claim 12
Dependent Claim
28 words
A magnetic recording medium according to claim 10, wherein said non-magnetic film is either one of Al, Ti, Cr, Ge, SiO 2 and Al 2 O 3 .
Claim 13
Dependent Claim
21 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is provided through an intermediary film with high permeability.
Claim 14
Dependent Claim
17 words
A magnetic recording medium according to claim 12, wherein said intermediary film is a Fe-Ni alloy film.
Claim 15
Dependent Claim
25 words
A magnetic recording medium according to claim 12, wherein said intermediary film is an amorphous film of the group consisting of Co-Zr, Fe-P-C and Fe-Co-Si-B.
Claim 16
Dependent Claim
22 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is a Co-Ni alloy layer formed by oblique vapor deposition.
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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) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |