US4555431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1984-02-06
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Granted: 1985-11-26
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Expires: 2004-02-06
Abstract
Abstract The tape running property of a magnetic recording medium is improved by provision a back layer. This magnetic recording medium comprises a magnetic layer on one side of a non-magnetic support and a back layer on the other side thereof, in which the magnetic layer consists mainly of a ferromagnetic metal powder and a binder and has a coercive force of at least 1000 Oe and a surface roughness of at most 0.03 μm, the ferromagnetic metal powder having a specific surface area of at least 35 m 2 /gr and a saturation magnetization of at least 120 emu/gr, while the back layer has a surface electric resistance of at most 1×10 10 Ω and a surface roughness of at most 0.05 μm.
Inventors
- 👤 Hajime Miyatsuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/714; G11B5/73; G11B5/739; G11B5/73923; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24942; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
106 words
A magnetic recording medium comprising a magnetic layer on one side of a non-magnetic support and a back layer on the other side thereof, in which the magnetic layer consists mainly of a ferromagnetic metal powder and a binder and has a coercive force of at least 1000 Oe and a surface roughness of at most 0.03 μm, the ferromagnetic powder having a specific surface area of at least 35 m 2 /gr and a saturation magnetization of at least 120 emu/gr, while the back layer has a surface electric resistance of at most 1×10 10 Ω and a surface roughness of at most 0.05 μm.
Claim 2
Dependent Claim
106 words
A magnetic recording medium comprising a magnetic layer on one side of a non-magnetic support and a back layer on the other side thereof, in which the magnetic layer consists mainly of a ferromagnetic metal powder and a binder and has a coercive force of at least 1000 Oe and a surface roughness of at most 0.03 μm, the ferromagnetic powder having a specific surface area of at least 35 m 2 /gr and a saturation magnetization of at least 120 emu/gr, while the back layer has a surface electric resistance of at most 1×10 10 Ω and a surface roughness of at most 0.05 μm.
Claim 3
Dependent Claim
25 words
The magnetic recording medium of claim 1, wherein the ferromagnetic metal powder is selected from the group consisting of powders of Fe, Fe--Ni and Fe--Ni--Co.
Claim 4
Dependent Claim
41 words
The magnetic recording medium of claim 2, wherein the ferromagnetic metal powder contains further a small amount of at least one element selected from the group consisting of B, C, N, Al, Si, P, S, Ti, Cr, Mn Cu and Zn.
Claim 5
Dependent Claim
36 words
The magnetic recording medium of claim 1, wherein the binder is selected from the group consisting of vinyl chloride-vinyl acetate copolymers, cellulosic resins, acrylic resins, polyamide resins, butadiene resins, urethane elastomers and isocyanate hardened type resins.
Claim 6
Dependent Claim
39 words
The magnetic recording medium of claim 1, wherein the ferromagnetic metal powder and binder are mixed in a proportion of 8 to 25 parts by weight of the binder to 100 parts by weight of the ferromagnetic metal powder.
Claim 7
Dependent Claim
22 words
The magnetic recording medium of claim 1, wherein the magnetic layer further contains at least one fatty acid or fatty acid ester.
Claim 8
Dependent Claim
28 words
The magnetic recording medium of claim 1, wherein the magnetic layer further contains at least one component selected from the group consisting of lubricants, abrasives and organic solvents.
Claim 9
Dependent Claim
17 words
The magnetic recording medium of claim 1, wherein the magnetic layer is subjected to a smoothening treatment.
Claim 10
Dependent Claim
20 words
The magnetic recording medium of claim 1, wherein the non-magnetic support is of a synthetic resin, non-magnetic metal or paper.
Claim 11
Dependent Claim
21 words
The magnetic recording medium of claim 9, wherein the non-magnetic support is in the form of a film, tape or sheet.
Claim 12
Dependent Claim
19 words
The magnetic recording medium of claim 1, wherein the magnetic layer has a thickness of at most 4 μm.
Claim 13
Dependent Claim
17 words
The magnetic recording medium of claim 1, wherein the back layer comprises a pigment and a binder.
Claim 14
Dependent Claim
54 words
The magnetic recording medium of claim 12, wherein the pigment is at least one member selected from the group consisting of carbon black, graphite, WS 2 , MoS 2 , BN, SiO 2 , CaCO 3 , Al 2 O 3 , Fe 2 O 3 , TiO 2 , MnO, ZnO and CaO.
Claim 15
Dependent Claim
35 words
The magnetic recording medium of claim 12, wherein the pigment and binder are mixed in a proportion of 1 to 4 parts by weight of the pigment to one part by weight of the binder.
Claim 16
Dependent Claim
19 words
The magnetic recording medium of claim 12, wherein the pigment has a particle size of at most 100 μm.
Claim 17
Dependent Claim
36 words
The magnetic recording medium of claim 12, wherein the binder is selected from the group consisting of vinyl chloride-vinyl acetate copolymers, cellulosic resins, acrylic resins, polyamide resins, butadiene resins, urethane elastomers and isocyanate hardened type resins.
Claim 18
Dependent Claim
19 words
The magnetic recording medium of claim 1, wherein the back layer has a thickness of at most 3 μm.
Claim 19
Dependent Claim
21 words
The magnetic recording medium of claim 1, wherein an undercoated layer is provided between the magnetic layer and the non-magnetic support.
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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) | 1988-11-25 | 1989-05-27 | 1989-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-25 | 1993-05-27 | 1993-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-25 | 1997-05-27 | 1997-11-26 | $7700.00 | Window Closed / Lapsed |