US4643941A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1985-04-18
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Granted: 1987-02-17
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Expires: 2005-04-18
Abstract
Abstract A magnetic recording medium is disclosed which comprises a non-magnetic support having provided thereon a magnetic layer, the magnetic layer comprising a first magnetic layer provided on the non-magnetic support containing ferromagnetic alloy particles and a second magnetic layer provided on the first magnetic layer containing hexagonal crystallized ferrite type magnetic particles, wherein the second magnetic layer has a thickness of 0.5 μm or less.
Inventors
- 👤 Takahito Miyoshi
- 👤 Masaaki Fujiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 02:03
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
99 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer, the magnetic layer comprising a first magnetic layer provided on the non-magnetic support containing ferromagnetic alloy particles having a specific surface area of 35 m 2 /g (S BET ) or more, and a second magnetic layer provided on the first magnetic layer containing hexagonal crystallized ferrite magnetic particles, wherein the second magnetic layer has a thickness of 0.5 μm or less, and the ratio of the thickness of said second magnetic layer to the thickness of said first magnetic layer is 1/10 or less.
Claim 2
Dependent Claim
99 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer, the magnetic layer comprising a first magnetic layer provided on the non-magnetic support containing ferromagnetic alloy particles having a specific surface area of 35 m 2 /g (S BET ) or more, and a second magnetic layer provided on the first magnetic layer containing hexagonal crystallized ferrite magnetic particles, wherein the second magnetic layer has a thickness of 0.5 μm or less, and the ratio of the thickness of said second magnetic layer to the thickness of said first magnetic layer is 1/10 or less.
Claim 3
Dependent Claim
29 words
The magnetic recording medium as claimed in claim 1, wherein the ferromagnetic alloy particles has a specific surface area of 45 m 2 /g (S BET ) or more.
Claim 4
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1, wherein the thickness of the first magnetic layer is 10 μm or less.
Claim 5
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1, wherein the thickness of the first magnetic layer is 5 μm or less.
Claim 6
Dependent Claim
40 words
The magnetic recording medium as claimed in claim 1, wherein said hexagonal crystallized ferrite particles are selected from the group consisting of berium ferrite, strontium ferrite, lead ferrite, substituted calcium ferrites, manganese bismuth or a hexagonal crystallized cobalt alloy thereof.
Claim 7
Dependent Claim
29 words
The magnetic recording medium as claimed in claim 1, wherein said hexagonal crystallized ferrite particles are selected from the group consisting of cobalt-substituted berium ferrite and cobalt-substituted strontium ferrite.
Claim 8
Dependent Claim
24 words
The magnetic recording medium as claimed in claim 1, wherein said hexagonal crystallized ferrite particles have a tabular diameter of 0.01 to 10 μm.
Claim 9
Dependent Claim
24 words
The magnetic recording medium as claimed in claim 7, wherein said hexagonal crystallized ferrite particles have a tabular diameter of 0.03 to 10 μm.
Claim 10
Dependent Claim
24 words
The magnetic recording medium as claimed in claim 1, wherein said hexagonal crystallized ferrite particles have a tabular thickness of 0.005 to 5 μm.
Claim 11
Dependent Claim
24 words
The magnetic recording medium as claimed in claim 9, wherein said hexagonal crystallized ferrite particles have a tabular thickness of 0.015 to 5 μm.
Claim 12
Dependent Claim
23 words
The magnetic recording medium as claimed in claim 1, wherein said hexagonal crystallized ferrite particles have a tabular ratio of 2 or more.
Claim 13
Dependent Claim
23 words
The magnetic recording medium as claimed in claim 11, wherein said hexagonal crystallized ferrite particles have a tabular ratio of 3 to 10.
Claim 14
Dependent Claim
32 words
The magnetic recording medium as claimed in claim 1, wherein the ratio of the thickness of said second magnetic layer to the thickness of said first magnetic layer is 1/20 or less.
Claim 15
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1, wherein the thickness of the second magnetic layer is 0.1 μm or less.
Claim 16
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 14, wherein the thickness of the second magnetic layer is 0.03 μm or less.
Claim 17
Dependent Claim
40 words
The magnetic recording medium as claimed in claim 1, wherein the proportion of the binder to the ferromagnetic alloy particles is 8 to 400 parts by weight of the binder per 100 parts by weight of the ferromagnetic alloy particles.
Claim 18
Dependent Claim
40 words
The magnetic recording medium as claimed in claim 16, wherein the proportion of the binder to the ferromagnetic alloy particles is 10 to 200 parts by weight of the binder per 100 parts by weight of the ferromagnetic alloy particles.
Claim 19
Dependent Claim
42 words
The magnetic recording medium as claimed in claim 1, wherein the proportion of the binder to the hexagonal crystallized ferrite particles is 8 to 400 parts by weight of the binder per 100 parts by weight of the hexagonal crystallized ferrite particles.
Claim 20
Dependent Claim
42 words
The magnetic recording medium as claimed in claim 1, wherein the proportion of the binder to the hexagonal crystallized ferrite particles is 10 to 200 parts by weight of the binder per 100 parts by weight of the hexagonal crystallized ferrite particles.
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) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |