US4069073A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of a ferromagnetic metal powder
Assignee: Fujifilm Holdings Corp
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Filing: 1975-10-02
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Granted: 1978-01-17
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Expires: 1995-10-02
Abstract
Abstract A ferromagnetic metal powder obtained by a reducing reaction of wet process or dry process is brought into contact with a solution containing phosphate ion. The ferromagnetic metal powder treated in this way is favorably used for magnetic recording media, in particular, suitable for high density recording.
Inventors
- 👤 Eiichi Tadokoro
- 👤 Masashi Aonuma
- 👤 Yasuo Tamai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:01
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70615; G11B5/70621; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
In a process for the production of a ferromagnetic metal powder containing at least 75% by weight of at least one metal selected from the group consisting of Fe, Co, Ni, Fe--Co, Fe--Ni, Co--Ni and Fe--Co--Ni by reducing a metal salt capable of forming the ferromagnetic metal powder with a reducing agent by a wet or dry process in the presence of a non-magnetic element or an organic compound, thus obtaining an oxidation resistant ferromagnetic metal powder, the improvement which comprises treating further the ferromagnetic metal powder separated from the reducing reaction system with a solution containing phosphate ions with a concentration of 0.00001 to 10 mols/liter at a temperature of from -10° to +120° C.
Claim 2
Dependent Claim
116 words
In a process for the production of a ferromagnetic metal powder containing at least 75% by weight of at least one metal selected from the group consisting of Fe, Co, Ni, Fe--Co, Fe--Ni, Co--Ni and Fe--Co--Ni by reducing a metal salt capable of forming the ferromagnetic metal powder with a reducing agent by a wet or dry process in the presence of a non-magnetic element or an organic compound, thus obtaining an oxidation resistant ferromagnetic metal powder, the improvement which comprises treating further the ferromagnetic metal powder separated from the reducing reaction system with a solution containing phosphate ions with a concentration of 0.00001 to 10 mols/liter at a temperature of from -10° to +120° C.
Claim 3
Dependent Claim
73 words
The process as claimed in claim 1, wherein the phosphate ion is formed from at least one source selected from the group consisting of phosphoric acid, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, ammonium phosphate, ammonium hydrogen phosphate, aluminum hydrogen phosphate, aluminum dihydrogen phosphate, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, ammonium sodium hydrogen phosphate, calcium dihydrogen phosphate, strontium hydrogen phosphate, manganous dihydrogen phosphate and magnesium hydrogen phosphate and mixtures thereof.
Claim 4
Dependent Claim
32 words
The process as claimed in claim 1, wherein the solution is a solution in at least one solvent selected from the group consisting of water, water-miscible organic polar solvents and mixtures thereof.
Claim 5
Dependent Claim
34 words
The process as claimed in claim 3, wherein the solvent is a mixture of the organic solvent and water in a proportion of 0 to 90% by weight of the organic solvent to water.
Claim 6
Dependent Claim
30 words
The process as claimed in claim 3, wherein the water-miscible organic polar solvents are methyl alchol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, dimethyl sulfoxide, dimethylformamide, tetahydrofuran and dioxane.
Claim 7
Dependent Claim
55 words
The process as claimed in claim 1, wherein the reducing reaction is carried out using a reducing agent selected from the group consisting of phosphinate ion-containing acids and salts, borohydride compounds and derivatives thereof such as sodium borohydride, diethylaminoborane and methylborante, hydrazine and derivatives thereof, and metallic powders such as magnesium, calcium and aluminum powders.
Claim 8
Dependent Claim
64 words
The process as claimed in claim 1, wherein the ferromagnetic metal powder further contains 20% by weight or less of at least one metal selected from the group consisting of Al, Si, S, Sc, Ti, V, Cr, Mn, An, Y, Mo, Rh, Pd, Ag, Sn, Sb, Te, Ba, Ta, W, Re, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, B, P and mixtures thereof.
Claim 9
Dependent Claim
30 words
The process as claimed in claim 1, wherein the ferromagnetic powder is subjected to an after-treatment comprising heating in an inert atmosphere or in the presence of water or oxygen.
Claim 10
Dependent Claim
20 words
A magnetic recording medium obtained by the use of the ferromagnetic metal powder produced by the process of claim 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) | 1981-01-16 | 1981-07-18 | 1982-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-16 | 1985-07-18 | 1986-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-16 | 1989-07-18 | 1990-01-17 | $7700.00 | Window Closed / Lapsed |