Patent US4414245A successfully refreshed from Google Patents.
US4414245A
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Process for producing cobalt containing ferromagnetic iron oxides
Assignee: Ishihara Sangyo Kaisha Ltd
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Filing: 1982-07-23
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Granted: 1983-11-08
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Expires: 2002-07-23
Abstract
Abstract A process which comprises coating a cobalt compound or a combination of a cobalt compound and a ferrous compound on the surface of magnetic iron oxide particles and then heating the coated particles in the presence of water vapor. The cobalt containing ferromagnetic iron oxide produced by this process is excellent in coercivity and thermal stability. Further, magnetic tape produced from this iron oxide has a high coercivity and is excellent in squareness, orientability and remanent induction.
Inventors
- 👤 Kokichi Miyazawa
- 👤 Kazuo Nakata
- 👤 Tsuneo Ishikawa
- 👤 Ichiro Honma
- 👤 Arata Koyama
- 👤 Masatoshi Amano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:08
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/70684; G11B5/70652; G11B5/70668; G11B5/70673
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
199 words
A process for producing a cobalt containing ferromagnetic iron oxide, which comprises treating magnetic iron oxide particles with a cobalt salt solution and an alkali or with a cobalt salt solution, a ferrous salt solution and an aklali to coat a cobalt compound or a cobalt compound and a ferrous compound on the surface of the particles the alkali being present at least in an amount equivalent to the cobalt salt or the cobalt and ferrous salts, the amount of cobalt coated being about 0.5-30% by weight based on the iron oxide, the amount of ferrous iron coated being about 1-30% by weight based on the iron oxide and said treating being effected in a non-oxidative atmosphere; separating the coated particles from the dispersion containing them and then heating the coated particles at a temperature of 60°-300° C. in an atmosphere in which the partial pressure of water vapor is at least 0.2 atm., said cobalt containing ferromagnetic iron oxide exhibiting a higher coercivity than a cobalt containing ferromagnetic iron oxide prepared as above absent said heating at a temperature of 60°-300° C. in an atmosphere in which the partial pressure of water vapor is at least 0.2 atm.
Claim 2
Dependent Claim
199 words
A process for producing a cobalt containing ferromagnetic iron oxide, which comprises treating magnetic iron oxide particles with a cobalt salt solution and an alkali or with a cobalt salt solution, a ferrous salt solution and an aklali to coat a cobalt compound or a cobalt compound and a ferrous compound on the surface of the particles the alkali being present at least in an amount equivalent to the cobalt salt or the cobalt and ferrous salts, the amount of cobalt coated being about 0.5-30% by weight based on the iron oxide, the amount of ferrous iron coated being about 1-30% by weight based on the iron oxide and said treating being effected in a non-oxidative atmosphere; separating the coated particles from the dispersion containing them and then heating the coated particles at a temperature of 60°-300° C. in an atmosphere in which the partial pressure of water vapor is at least 0.2 atm., said cobalt containing ferromagnetic iron oxide exhibiting a higher coercivity than a cobalt containing ferromagnetic iron oxide prepared as above absent said heating at a temperature of 60°-300° C. in an atmosphere in which the partial pressure of water vapor is at least 0.2 atm.
Claim 3
Dependent Claim
24 words
The process according to claim 1, wherein an additional heating is carried out at a temperature of 100°-300° C. in an inert gas atmosphere.
Claim 4
Dependent Claim
24 words
The process according to claim 1, wherein an additional heating is carried out at a temperature of 130°-250° C. in an inert gas atmosphere.
Claim 5
Dependent Claim
18 words
The process according to claim 1, wherein the heating is carried out at a temperature of 60°-250° C.
Claim 6
Dependent Claim
18 words
The process according to claim 1, wherein the heating is carried out at a temperature of 80°-180° C.
Claim 7
Dependent Claim
18 words
The process according to claim 1, wherein the heating is carried out at a temperature of 80°-150° C.
Claim 8
Dependent Claim
28 words
The process according to claim 1, wherein the heating is carried out in an atmosphere in which the partial pressure of water vapor is 0.4 atm. or more.
Claim 9
Dependent Claim
21 words
The process according to claim 1, wherein the heating is carried out at said temperature under a saturated water vapor pressure.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |