US3943012A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1974-08-19
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Granted: 1976-03-09
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Expires: 1994-08-19
Abstract
Abstract A magnetic recording medium for high density recording comprising a support having thereon a magnetic recording layer comprising a ferromagnetic metal powder of the Fe-Co-Cr-B system and having a coercive force of about 700 to 500 oersteds in the oriented direction of the magnetic substance and a residual magnetic flux density of about 1500 gausses or more, the residual magnetic flux density of which after storage for 160 hours under the conditions of a temperature of 60°C and 90%RH is 85% or more of the initial value thereof before storage under these conditions in a binder. The magnetic recording medium is especially suitable for high density recording, having sufficient sensitivity and excellent resistance.
Inventors
- 👤 Yasuo Tamai
- 👤 Masashi Aonuma
- 👤 Matsuaki Nakamura
- 👤 Hiroshi Agawa
- 👤 Goro Akashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:08
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70615; G11B5/70621
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
156 words
A magnetic recording medium comprising a support having thereon a magnetic recording layer comprising a binder and a ferromagnetic alloy powder, said magnetic recording layer having a coercive force of about 700 to 1500 oersteds in the oriented direction of the ferromagnetic powder and a residual magnetic flux density of about 1500 gausses or higher, the residual magnetic flux density of which after storage for 160 hours in an atomosphere of 60° C and 90% RH is 85% or higher of the initial value thereof before said storage, and said ferromagnetic alloy powder comprising the reaction product of reducing a mixed solution containing Fe, Co and Cr ions with a borohydride compound reducing agent, said mixed solution containing metal ions ranging from 0.01 to 0.5 mole/liter in concentration, such that said ferromagnetic alloy powder comprises about 65 to 89% Fe, about 7 to 34% Co, and about 0.5 to 5% Cr, said percentages being by weight.
Claim 2
Dependent Claim
156 words
A magnetic recording medium comprising a support having thereon a magnetic recording layer comprising a binder and a ferromagnetic alloy powder, said magnetic recording layer having a coercive force of about 700 to 1500 oersteds in the oriented direction of the ferromagnetic powder and a residual magnetic flux density of about 1500 gausses or higher, the residual magnetic flux density of which after storage for 160 hours in an atomosphere of 60° C and 90% RH is 85% or higher of the initial value thereof before said storage, and said ferromagnetic alloy powder comprising the reaction product of reducing a mixed solution containing Fe, Co and Cr ions with a borohydride compound reducing agent, said mixed solution containing metal ions ranging from 0.01 to 0.5 mole/liter in concentration, such that said ferromagnetic alloy powder comprises about 65 to 89% Fe, about 7 to 34% Co, and about 0.5 to 5% Cr, said percentages being by weight.
Claim 3
Dependent Claim
26 words
The magnetic recording medium claimed in claim 1, wherein the borohydride compound is in a solution having a hydroxide ion concentration of about 0.001N to 0.6N.
Claim 4
Dependent Claim
40 words
The magnetic recording medium as claimed in claim 1, wherein Br/Hc of the ferromagnetic metal powder is about 1.5 to 4.5, in which Hc is the coercive force in oersteds and Br is the residual magnetic flux density in gausses.
Claim 5
Dependent Claim
16 words
The magnetic recording medium as claimed in claim 3, wherein the Br/Hc is 3.8 to 2.0.
Claim 6
Dependent Claim
28 words
The magnetic recording medium as claimed in claim 1 wherein the proportion of the respective metal components is within the range of the cross-hatched portion in FIG. 1.
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) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |