US4623405A
Expired / Lapsed
US
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Metallic magnetic powder
Assignee: TDK Corp
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Filing: 1985-08-14
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Granted: 1986-11-18
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Expires: 2005-08-14
Abstract
Abstract A metallic magnetic powder treated with an alkyl group-containing dicarboxylic acid so that the acid is deposited on the particle surfaces. The amount of the acid so deposited ranges from 0.5 to 5% on the basis of the weight of the starting powder.
Inventors
- 👤 Kiminori Tamai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:11
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
21 words
A metallic magnetic powder treated with an alkyl group-containing dicarboxylic acid so that the acid is deposited on the particle surfaces.
Claim 2
Dependent Claim
21 words
A metallic magnetic powder treated with an alkyl group-containing dicarboxylic acid so that the acid is deposited on the particle surfaces.
Claim 3
Dependent Claim
39 words
A metallic magnetic powder according to claim 1 wherein the amount of the alkyl group-containing dicarboxylic acid deposited on the particle surfaces ranges from 0.1 to 10% on the basis of the weight of the starting metallic magnetic powder.
Claim 4
Dependent Claim
34 words
A metallic magnetic powder according to claim 2 wherein the amount of the alkyl group-containing dicarboxylic acid ranges from 0.5 to 5% on the basis of the weight of the starting metallic magnetic powder.
Claim 5
Dependent Claim
16 words
A metallic magnetic powder according to claim 1 wherein said powder is for magnetic recording media.
Claim 6
Dependent Claim
21 words
A metallic magnetic powder according to claim 1 wherein said metallic magnetic powder is selected from iron-cobalt, iron-nickel-cobalt and iron-cobalt-chromium alloys.
Claim 7
Dependent Claim
36 words
A metallic magnetic powder according to claim 1 wherein said alkyl group of the alkyl group-containing dicarboxylic acid is selected from the group consisting of straight-or branched chain alkyls having carbon atoms of 3 to 7.
Claim 8
Dependent Claim
39 words
A metallic magnetic powder according to claim 6 wherein the acid of the alkyl group-containing dicarboxylic acid is selected from the group consisting of malonic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid and isophthalic acid.
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) | 1989-11-17 | 1990-05-19 | 1990-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-17 | 1994-05-19 | 1994-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-17 | 1998-05-19 | 1998-11-18 | $7700.00 | Window Closed / Lapsed |