US4565726A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording media having ferromagnetic and ferrite particles in the magnetic layer thereof
Assignee: Toshiba Corp
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Filing: 1983-04-26
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Granted: 1986-01-21
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Expires: 2003-04-26
Abstract
Abstract Disclosed is a magnetic recording medium, characterized in that 5 to 100 parts by weight of hexagonal ferrite particles having an average particle diameter of 0.01 to 0.2 μm and 100 parts by weight of ferromagnetic particles having a saturation magnetization of 72 to 220 emu/g and an average particle diameter larger than that of the hexagonal ferrite particles are dispersed in a resinous binder.
Inventors
- 👤 Toshihiko Oguchi
- 👤 Hirohisa Kato
- 👤 Moriyasu Wada
- 👤 Toshimitsu Asano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:14
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/258
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
106 words
A magnetic recording medium comprising 5 to 100 parts by weight of hexagonal ferrite particles having an average particle diameter of 0.01 to 0.2 microns, and 100 parts by weight of ferromagnetic particles having a saturation magnetization of 70 to 220 emu/g and an average particle diameter within the range of 0.05 to 1 microns, said hexagonal ferrite particles and said ferromagnetic particles being dispersed in a single layer comprised of a resinous binder, wherein the said hexagonal ferrite particles have a coercive force (iHc) of from 600 to 2000 Oe, and said ferromagnetic particles have a coercive force (iHc) of from 300 to 2000 Oe.
Claim 2
Dependent Claim
106 words
A magnetic recording medium comprising 5 to 100 parts by weight of hexagonal ferrite particles having an average particle diameter of 0.01 to 0.2 microns, and 100 parts by weight of ferromagnetic particles having a saturation magnetization of 70 to 220 emu/g and an average particle diameter within the range of 0.05 to 1 microns, said hexagonal ferrite particles and said ferromagnetic particles being dispersed in a single layer comprised of a resinous binder, wherein the said hexagonal ferrite particles have a coercive force (iHc) of from 600 to 2000 Oe, and said ferromagnetic particles have a coercive force (iHc) of from 300 to 2000 Oe.
Claim 3
Dependent Claim
24 words
The magnetic recording medium according to claim 1, wherein the average particle diameter of said hexagonal ferrite particles ranges from 0.05 to 0.1 μm.
Claim 4
Dependent Claim
23 words
The magnetic recording medium according to claim 1, wherein said hexagonal ferrite has a coercive force (iHc) of from 700 to 1500 Oe.
Claim 5
Dependent Claim
16 words
The magnetic recording medium according to claim 1, wherein said ferromagnetic particles are particles of γ-ferrite.
Claim 6
Dependent Claim
24 words
The magnetic recording medium according to claim 1, wherein the amount of said hexagonal ferrite particles ranges from 10 to 50 parts by weight.
Claim 7
Dependent Claim
74 words
The magnetic recording medium according to claim 1, wherein said hexagonal ferrite is selected from the group consisting of Ba-ferrite, Sr-ferrite, Ca-ferrite, Pb-ferrite and substituted Ba-ferrite represented by the following formula: BaO.n[(Fe.sub.1-m M.sub.m).sub.2 O.sub.3 ] wherein, M denotes at least one element selected from the group consisting of Co, Ti, Zn, Ni, Mn, In, Cu, Ge and Nb, and m and n stand respectively for values of 0 to 0.2 and 5.4 to 6.0.
Claim 8
Dependent Claim
17 words
The magnetic recording medium according to claim 6, wherein said hexagonal ferrite is Ba-ferrite or substituted Ba-ferrite.
Claim 9
Dependent Claim
53 words
The magnetic recording medium according to claim 1, wherein said ferromagnetic particles are particles of a metal selected from the group consisting of Fe, Ni, Co and Cr; particles of alloys made of two or more of Fe, Ni, Co and Cr; magnetite particles; γ-ferrite particles; Co-modified magnetite particles; and Co-modified γ-ferrite particles.
Claim 10
Dependent Claim
21 words
The magnetic recording medium according to claim 8, wherein said ferromagnetic particles have a saturation magnetization of 75 to 150 emu/g.
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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) | 1989-01-20 | 1989-07-22 | 1990-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-20 | 1993-07-22 | 1994-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-20 | 1997-07-22 | 1998-01-21 | $7700.00 | Window Closed / Lapsed |