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US4828916A
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Plate-like magnetoplumbite type ferrite particles for magnetic recording and magnetic recording media using the same
Assignee: Toda Kogyo Corp
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Filing: 1987-12-09
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Granted: 1989-05-09
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Expires: 2007-12-09
Abstract
Abstract Disclosed herein are Ba-containing plate like magnetoplumbite type ferrite particles for magnetic recording having the composition of AO.n{(Fe 1-X M X ) 2 O 3 } (wherein A represents Ba or Ba and Sr, M represents Zn and Ti, or Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25) and the change of coercive force of said particles at a temperature of 20°-120° C. in the range of -2.0 Oe/°C. to +2.0 Oe/°C., and magnetic recording media using the same.
Inventors
- 👤 Shigehisa Yamamoto
- 👤 Ryuji Fujita
- 👤 Kazutoshi Sanada
- 👤 Nanao Horiishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:15
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
83 words
Ba-containing plate-like magnetoplumbite type ferrite particles for magnetic recording having a composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn and Ti, or Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, said particles having an average particle diameter of 0.05 to 0.3 μm and a change of coercive force (temperature stability) of said particles at a temperature of 20°-120° C. in the range of -2.0 Oe/° C. to +2.0 Oe/° C.
Claim 2
Dependent Claim
83 words
Ba-containing plate-like magnetoplumbite type ferrite particles for magnetic recording having a composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn and Ti, or Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, said particles having an average particle diameter of 0.05 to 0.3 μm and a change of coercive force (temperature stability) of said particles at a temperature of 20°-120° C. in the range of -2.0 Oe/° C. to +2.0 Oe/° C.
Claim 3
Dependent Claim
72 words
Ba-containing plate-like magnetoplumbite type ferrite particles according to claim 1, wherein said particles have the composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, and the change of coercive force (temperature stability) of said particles at a temperature of 20°-120° C. is in the range of -1.5 Oe/° C. to +1.5 Oe/° C.
Claim 4
Dependent Claim
33 words
Ba-containing plate-like magnetoplumbite type ferrite particles according to claim 1, wherein a coercive force of said particles is 300 to 2,000 Oe and a magnetization of said particles is 45 to 60 emu/g.
Claim 5
Dependent Claim
95 words
Magnetic recording media obtained by coating on a substrate a resin composition containing Ba-containing plate-like magnetoplumbite type ferrite particles having the composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn and Ti, or Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, said particles having an average particle diameter of 0.05 to 0.3 μm, the change of coercive force (temperature stability) of said magnetic recording media at a temperature of 20°-90° C. being in the range of -2.0 Oe/° C. to +2.0 Oe/° C.
Claim 6
Dependent Claim
95 words
Magnetic recording media obtained by coating on a substrate a resin composition containing Ba-containing plate-like magnetoplumbite type ferrite particles having the composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn and Ti, or Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, said particles having an average particle diameter of 0.05 to 0.3 μm, the change of coercive force (temperature stability) of said magnetic recording media at a temperature of 20°-90° C. being in the range of -2.0 Oe/° C. to +2.0 Oe/° C.
Claim 7
Dependent Claim
71 words
Magnetic recording media according to claim 4, wherein said particles have the composition of AO.n{(Fe 1-x M x ) 2 O 3 }, wherein A represents Ba or Ba and Sr, M represents Zn, Co and Ti, n=6.5-11.0, and x=0.05-0.25, and the change of coercive force (temperature stability) of said magnetic recording media at a temperature of 20°-90° C. is in the range of -1.5 Oe/° C. to +1.5 OE/° C.
Claim 8
Dependent Claim
21 words
Magnetic recording media according to claim 4, wherein a coercive force of said magnetic recording media is 300 to 2,000 Oe.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
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