Patent US4239637A successfully refreshed from Google Patents.
US4239637A
Expired / Lapsed
US
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Magnetic material for recording media
Assignee: Victor Company of Japan Ltd
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Filing: 1979-02-07
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Granted: 1980-12-16
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Expires: 1999-02-07
Abstract
Abstract A magnetic material for magnetic recording media, comprising acicular particles of a conventional magnetic material and a ferrite powder amounting to about 0.5-20 Wt% of the acicular particles. Preferably the ferrite powder has a roundish particle shape. The use of this magnetic material in the form of a dispersion of the acicular magnetic particles and the ferrite particles in a usual binder makes it possible to afford improved rectangular ratio to the recording media by a conventional orientation process.
Inventors
- 👤 Tunehide Naruse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:51
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
116 words
A magnetic material for magnetic recording media, comprising: acicular particles of a magnetic substance selected from the group consisting of γ--Fe 2 O 3 , Co-containing γ--Fe 2 O 3 , and Co-containing Fe 3 O 4 , said acicular particles having a mean length in the range of from about 0.3 μm to about 2.0 μm; and particles of a ferrite selected from the group consisting of Mn-ferrite, Zn-ferrite and Mn--Zn ferrite, said particles of said ferrite amounting to from about 0.5% to about 20% by weight of said acicular particles and having a generally spherical particle shape and a mean particle size in the range of from about 0.2 μm to about 2.0 μm.
Claim 2
Dependent Claim
116 words
A magnetic material for magnetic recording media, comprising: acicular particles of a magnetic substance selected from the group consisting of γ--Fe 2 O 3 , Co-containing γ--Fe 2 O 3 , and Co-containing Fe 3 O 4 , said acicular particles having a mean length in the range of from about 0.3 μm to about 2.0 μm; and particles of a ferrite selected from the group consisting of Mn-ferrite, Zn-ferrite and Mn--Zn ferrite, said particles of said ferrite amounting to from about 0.5% to about 20% by weight of said acicular particles and having a generally spherical particle shape and a mean particle size in the range of from about 0.2 μm to about 2.0 μm.
Claim 3
Dependent Claim
115 words
A magnetic material for magnetic recording media, comprising: acicular particles of a magnetic substance selected from the group consisting of γ--Fe 2 O 3 , Co-containing γ--Fe 2 O 3 , and Co-containing Fe 3 O 4 , said acicular particles having a mean length in the range of from about 0.3 μm to about 2.0 μm; and particles of a ferrite selected from the group consisting Mn-ferrite, Zn-ferrite and Mn--Zn ferrite, said particles of said ferrite amounting to from about 0.5% to about 20% by weight of said acicular particles and having a generally ellipsoidal particle shape and a mean particle size in the range of from about 0.2 μm to about 2.0 μm.
Claim 4
Dependent Claim
115 words
A magnetic material for magnetic recording media, comprising: acicular particles of a magnetic substance selected from the group consisting of γ--Fe 2 O 3 , Co-containing γ--Fe 2 O 3 , and Co-containing Fe 3 O 4 , said acicular particles having a mean length in the range of from about 0.3 μm to about 2.0 μm; and particles of a ferrite selected from the group consisting Mn-ferrite, Zn-ferrite and Mn--Zn ferrite, said particles of said ferrite amounting to from about 0.5% to about 20% by weight of said acicular particles and having a generally ellipsoidal particle shape and a mean particle size in the range of from about 0.2 μm to about 2.0 μm.
Claim 5
Dependent Claim
32 words
A magnetic material according to claim 1, or 2, further comprising a high polymer as a binder, said acicular particles and said particles of said ferrite being uniformly dispersed in said binder.
References Cited (Backward Citations)
US3740266A
Cited
US4002804A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-16 | 1984-06-16 | 1984-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-16 | 1988-06-16 | 1988-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-16 | 1992-06-16 | 1992-12-16 | $7700.00 | Window Closed / Lapsed |