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US4529524A
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Process for producing plate-like barium ferrite particles for magnetic recording
Assignee: Toda Kogyo Corp
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Filing: 1984-10-29
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Granted: 1985-07-16
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Expires: 2004-10-29
Abstract
Abstract Disclosed herein is a process for producing plate-like barium ferrite particles for magnetic recording, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and a divalent metal other than Co as M(II), and autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200° to 330° C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III).
Inventors
- 👤 Norimichi Nagai
- 👤 Nanao Horiishi
- 👤 Masao Kiyama
- 👤 Toshio Takada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:16
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; C; C01; C01G; C01G49/00; C01G49/0018; C01G49/0036; B; B82; B82Y; B82Y30/00; C01G49/0063; C01G49/0072; C01G49/009; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/20; C01P2004/60; C01P2004/62; C01P2004/64; C01P2006/00; C01P2006/12; C01P2006/42; C01P2006/60; C01P2006/80
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
A process for producing plate-like barium ferrite particles for magnetic recording exhibiting an H c of 500 to 1,000 Oe, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, said divalent metal being Zn(II) or Mn(II), which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and the divalent metal other than Co as M(II), in such an amount that the atomic ratio of Si(IV) to Fe(III) is in the range of 0.0025 to 0.036, and autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200° to 330° C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III).
Claim 2
Dependent Claim
150 words
A process for producing plate-like barium ferrite particles for magnetic recording exhibiting an H c of 500 to 1,000 Oe, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, said divalent metal being Zn(II) or Mn(II), which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and the divalent metal other than Co as M(II), in such an amount that the atomic ratio of Si(IV) to Fe(III) is in the range of 0.0025 to 0.036, and autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200° to 330° C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III).
Claim 3
Dependent Claim
29 words
A process according to claim 1, wherein in the aqueous highly alkaline suspension the atomic ratio of total sum of M(II) and Ti(IV) to Fe(III) is 0.01:1 to 0.25:1.
Claim 4
Dependent Claim
20 words
A process according to claim 1, wherein the source of Fe(III) is ferric chloride, ferric nitrate or powdery ferric oxyhydroxide.
Claim 5
Dependent Claim
19 words
A process according to claim 1, wherein the source of Ba(II) is barium hydroxide, barium nitrate or barium chloride.
Claim 6
Dependent Claim
17 words
A process according to claim 1, wherein the source of Co(II) is cobalt nitrate or cobalt chloride.
Claim 7
Dependent Claim
17 words
A process according to claim 1, wherein the source of Ti(IV) is titanium chloride or alkali titanate.
Claim 8
Dependent Claim
12 words
A process according to claim 1, wherein x is equal to y.
Claim 9
Dependent Claim
174 words
A process for producing plate-like barium ferrite particles for magnetic recording exhibiting an H c of 500 to 1,000 Oe, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, said divalent metal being Zn(II) or Mn(II), which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and the divalent metal other than Co as M(II), in such an amount that the atomic ratio of Si(IV) to Fe(III) is in the range of 0.0025 to 0.036, autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200° to 300° C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III), and subjecting the thus obtained particles to thermal treatment at a temperature of not more than 900° C. to improve the magnetization of said particles.
Claim 10
Dependent Claim
174 words
A process for producing plate-like barium ferrite particles for magnetic recording exhibiting an H c of 500 to 1,000 Oe, represented by the formula: BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 wherein x and y are independently not more than 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, said divalent metal being Zn(II) or Mn(II), which comprises adding a compound of Si(IV) to an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and the divalent metal other than Co as M(II), in such an amount that the atomic ratio of Si(IV) to Fe(III) is in the range of 0.0025 to 0.036, autoclaving the resultant aqueous highly alkaline suspension of ferric hydroxide at the temperature of 200° to 300° C., thereby obtaining the plate-like barium ferrite particles having the thickness thereof controlled according to the atomic ratio of Si(IV) to Fe(III), and subjecting the thus obtained particles to thermal treatment at a temperature of not more than 900° C. to improve the magnetization of said particles.
Claim 11
Dependent Claim
29 words
A process according to claim 8, wherein in the aqueous highly alkaline suspension the atomic ratio of total sum of M(II) and Ti(IV) to Fe(III) is 0.01:1 to 0.25:1.
Claim 12
Dependent Claim
20 words
A process according to claim 8, wherein the source of Fe(III) is ferric chloride, ferric nitrate or powdery ferric oxyhydroxide.
Claim 13
Dependent Claim
19 words
A process according to claim 8, wherein the source of Ba(II) is barium hydroxide, barium nitrate or barium chloride.
Claim 14
Dependent Claim
17 words
A process according to claim 8, wherein the source of Co(II) is cobalt nitrate or cobalt chloride.
Claim 15
Dependent Claim
17 words
A process according to claim 8, wherein the source of Ti(IV) is titanium chloride or alkali titanate.
Claim 16
Dependent Claim
12 words
A process according to claim 8, wherein x is equal to y.
References Cited (Backward Citations)
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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) | 1988-07-15 | 1989-01-14 | 1989-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-15 | 1993-01-14 | 1993-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-15 | 1997-01-14 | 1997-07-16 | $7700.00 | Window Closed / Lapsed |