Patent US4632870A successfully refreshed from Google Patents.
US4632870A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1985-02-15
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Granted: 1986-12-30
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Expires: 2005-02-15
Abstract
Abstract A magnetic recording medium comprising a plastic base of polyester film or the like having a magnetic coat formed on one side, the magnetic coat consisting of a dispersion of a ferromagnetic powder in a resin binder, characterized in that the magnetic coat contains a nonmagnetic composite oxide powder of a spinel structure in an amount of 0.5 to 15% by weight on the basis of the ferromagnetic powder weight. The composite oxide in powder form ranges in particle diameter from 0.1 to 0.7 μm and has a Mohs hardness of not less than 5.
Inventors
- 👤 Shigeru Takamatsu
- 👤 Yuji Ishihara
- 👤 Masahiro Takizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:45
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
69 words
A magnetic recording medium comprising a plastic base and a magnetic coat formed thereon which comprises a ferromagnetic powder dispersed in a resin binder, said magnetic coat also containing finely divided nonmagnetic particles of the composite oxide of zinc and aluminum having a spinel structure and the general formula ZnAl 2 O 4 and having an average particle diameter of 0.1 to 0.7 μm as measured by electron microphotography.
Claim 2
Dependent Claim
69 words
A magnetic recording medium comprising a plastic base and a magnetic coat formed thereon which comprises a ferromagnetic powder dispersed in a resin binder, said magnetic coat also containing finely divided nonmagnetic particles of the composite oxide of zinc and aluminum having a spinel structure and the general formula ZnAl 2 O 4 and having an average particle diameter of 0.1 to 0.7 μm as measured by electron microphotography.
Claim 3
Dependent Claim
32 words
A magnetic recording medium according to claim 1 wherein said composite oxide of zinc and aluminum has a hardness in the range of from about 5 to 9 on the Mohs scale.
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) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |