US4496626A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1982-02-23
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Granted: 1985-01-29
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Expires: 2002-02-23
Abstract
Abstract A magnetic recording medium for high-density recording, which comprises a non-magnetic substrate and a magnetic layer provided on the non-magnetic substrate and containing, as main constituents, ferromagnetic grains and a binder, wherein the non-magnetic substrate surface on the side adjoining the magnetic layer has a surface roughness higher than that of the back surface of the non-magnetic substrate. The substrate surface adjoining the magnetic layer has a surface roughness of 0.007μ or more, while the back surface has a surface roughness of 0.02μ or less, but in each particular application the roughness of the surface adjoining the magnetic layer is selected to be higher than that of the back surface.
Inventors
- 👤 Akira Kasuga
- 👤 Noburo Hibino
- 👤 Hajime Miyatsuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:21
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
68 words
A magnetic recording medium which comprises a non-magnetic substrate and a magnetic layer provided on said non-magnetic substrate and containing, as main constituents, ferromagnetic grains and a binder, wherein the surface roughness of the non-magnetic substrate surface on the side adjoining said magnetic layer is 0.007μ or more and is higher than the surface roughness of the back surface of said non-magnetic substrate which is 0.02μ or less.
Claim 2
Dependent Claim
68 words
A magnetic recording medium which comprises a non-magnetic substrate and a magnetic layer provided on said non-magnetic substrate and containing, as main constituents, ferromagnetic grains and a binder, wherein the surface roughness of the non-magnetic substrate surface on the side adjoining said magnetic layer is 0.007μ or more and is higher than the surface roughness of the back surface of said non-magnetic substrate which is 0.02μ or less.
Claim 3
Dependent Claim
27 words
A magnetic recording medium as defined in claim 1 wherein said ferromagnetic grains are metal or alloy fine grains, and said non-magnetic substrate is a plastic film.
Claim 4
Dependent Claim
44 words
A magnetic recording medium as defined in claim 1 wherein said ferromagnetic grains essentially consist of about 75 wt. % or more of metal content, and about 25 wt. % or less of hydrogen or oxygen in the form of water, hydroxide or oxide.
Claim 5
Dependent Claim
26 words
A magnetic recording medium as defined in claim 3 wherein said metal content includes about 80 wt. % or more of at least one ferromagnetic metal.
Claim 6
Dependent Claim
39 words
A magnetic recording medium as defined in claim 4 wherein said at least one ferromagnetic metal essentially consists of about 50 wt. % or more of Fe, and about 50 wt. % or less of Co, Ni or Co-Ni.
Claim 7
Dependent Claim
27 words
A magnetic recording medium as defined in claim 1 wherein the surfaces of said ferromagnetic grains are oxidized to obtain an oxygen content of 5% or more.
Claim 8
Dependent Claim
32 words
A magnetic recording medium as defined in claim 1 wherein said binder is a thermoplastic resin, a thermosetting resin, a reactive resin, or a mixture of two or more of these resins.
Claim 9
Dependent Claim
38 words
A magnetic recording medium as defined in claim 1 wherein said magnetic layer contains a binder in a proportion within the range of 8 to 25 parts by weight per 100 parts by weight of said ferromagnetic grains.
Claim 10
Dependent Claim
26 words
A magnetic recording medium as defined in claim 1 wherein said magnetic layer has a thickness within the range of 0.5μ to 6μ in dry state.
References Cited (Backward Citations)
US3967025A
Cited
US4071654A
Cited
US4153920A
Cited
US4202927A
Cited
US4348446A
Cited
JPS54143111A
Cited
US4461797A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-29 | 1988-07-30 | 1989-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-29 | 1992-07-30 | 1993-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-29 | 1996-07-30 | 1997-01-29 | $7700.00 | Window Closed / Lapsed |