US3607218A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of magnetic substances
Assignee: Fujifilm Holdings Corp
•
Filing: 1969-08-28
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Granted: 1971-09-21
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Expires: 1989-08-28
Abstract
Abstract Producing ferromagnetic metal powders by the reduction of a ferromagnetic metal salt using hypophosphite ions can be improved by adding a viscosity increasing material to the aqueous reaction system.
Inventors
- 👤 Goro Akashi
- 👤 Masaaki Fujiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:46
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/065; B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
34 words
The process as claimed in claim 1 wherein said viscosity increasing agent is selected from the group consisting of gelatin, a maleic anhydride-vinyl acetate copolymer, water glass, polyvinyl alcohol, carboxymethylcellulose, glycerine, and polyethylene glycol.
Claim 2
Dependent Claim
62 words
In a process for producing ferromagnetic metal powders by reducing at least one salt of a ferromagnetic metal in an aqueous solution in the presence of hypophosphite ions, the improvement which comprises adding a viscosity increasing agent to said aqueous solution preliminary to reaction to increase the viscosity of said solution and carrying out said reducing reaction while applying a magnetic field.
Claim 3
Dependent Claim
34 words
The process as claimed in claim 3 wherein said viscosity increasing agent is selected from the group consisting of gelatin, a maleic anhydride-vinyl acetate copolymer, water glass, polyvinyl alcohol, carboxymethylcellulose, glycerine, and polyethylene glycol.
Claim 4
Dependent Claim
23 words
The process of claim 3 wherein said reducing reaction is further carried out under the application of ultrasonic vibrations to the reacTion system.
Claim 5
Dependent Claim
19 words
The process of claim 1 wherein the viscosity of said aqueous solution is at least greater than 2 centipoises.
Claim 6
Dependent Claim
19 words
The process of claim 3 wherein the viscosity of said aqueous solution is at least greater than 2 centipoises.
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) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |