US4332863A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1980-08-05
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Granted: 1982-06-01
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Expires: 2000-08-05
Abstract
Abstract A magnetic recording medium comprises a substrate coated with a binder and a magnetic powder obtained by forming an oleic acid layer on a surface of a metal or alloy magnetic powder obtained by a dry reduction.
Inventors
- 👤 Akihiko Hosaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:11
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
89 words
A magnetic recording medium comprising a substrate coated with a magnetic composition, said composition having been obtained by (1) dry reducing a metal oxide powder in a hydrogen atmosphere, (2) maintaining the resulting magnetic powder in an inert medium to prevent contact with an oxidizing atmosphere, (3) dispersing the magnetic powder in an inert medium solution of oleic acid to form an oleic acid layer on the surface of the powder, (4) drying the coated magnetic powder, and (5) incorporating the dried, coated magnetic powder into the magnetic composition.
Claim 2
Dependent Claim
89 words
A magnetic recording medium comprising a substrate coated with a magnetic composition, said composition having been obtained by (1) dry reducing a metal oxide powder in a hydrogen atmosphere, (2) maintaining the resulting magnetic powder in an inert medium to prevent contact with an oxidizing atmosphere, (3) dispersing the magnetic powder in an inert medium solution of oleic acid to form an oleic acid layer on the surface of the powder, (4) drying the coated magnetic powder, and (5) incorporating the dried, coated magnetic powder into the magnetic composition.
Claim 3
Dependent Claim
30 words
The magnetic recording medium of claim 1 wherein the metal oxide powder is subjected to a heat-treatment in an inert gas prior to the dry reduction in a hydrogen atmosphere.
References Cited (Backward Citations)
US3790407A
Cited
US3900593A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-31 | 1985-11-30 | 1986-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-31 | 1989-11-30 | 1990-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-31 | 1993-11-30 | 1994-06-01 | $7700.00 | Window Closed / Lapsed |