US4592942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1984-09-20
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Granted: 1986-06-03
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Expires: 2004-09-20
Abstract
Abstract A magnetic recording medium comprising a non-magnetic substrate, a magnetic recording layer formed on one side of the substrate and a back coating layer on the other side of the substrate, characterized in that the back coating layer is a coating composed essentially of carbon black, a resin binder and a lubricant, the weight ratio of the carbon black to the binder being from 1:1 to 1:4, and the carbon black having a particle size of from 10 to less than 100 mμm.
Inventors
- 👤 Masaharu Nishimatsu
- 👤 Toshiaki Ide
- 👤 Hiroyuki Arioka
- 👤 Yuichi Kubota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/735; G11B5/7356; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24372; Y10T428/24413; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
83 words
A magnetic recording medium comprising a non-magnetic substrate, a magnetic recording layer formed on one side of the substrate and a back coating layer on the other side of the substrate, characterized in that the back coating layer is a coating composed essentially of carbon black, a resin binder and a lubricant, the weight ratio of the carbon black to the binder being from 1:1 to 1:4, and the carbon black having a particle size of from 10 to less than 100 mμm.
Claim 2
Dependent Claim
83 words
A magnetic recording medium comprising a non-magnetic substrate, a magnetic recording layer formed on one side of the substrate and a back coating layer on the other side of the substrate, characterized in that the back coating layer is a coating composed essentially of carbon black, a resin binder and a lubricant, the weight ratio of the carbon black to the binder being from 1:1 to 1:4, and the carbon black having a particle size of from 10 to less than 100 mμm.
Claim 3
Dependent Claim
66 words
The magnetic recording medium according to claim 1, wherein the magnetic recording layer is composed essentially of a ferromagnetic alloy powder dispersed in a resin binder and having a specific surface area of at least 48 m 2 /g as measured by BET method, said magnetic recording layer having a coercive force of at least 1,000 Oe and a surface roughness of at most 0.08 μm.
Claim 4
Dependent Claim
20 words
The magnetic recording medium according to claim 1, wherein the magnetic recording layer is composed of a thin ferromagnetic layer.
Claim 5
Dependent Claim
22 words
The magnetic recording medium according to claim 1, wherein the carbon black has a particle size of from 20 to 80 mμm.
Claim 6
Dependent Claim
23 words
The magnetic recording medium according to claim 1, wherein the lubricant is a fatty acid, a fatty acid ester or a mixture thereof.
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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) | 1989-06-02 | 1989-12-02 | 1990-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-02 | 1993-12-02 | 1994-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-02 | 1997-12-02 | 1998-06-03 | $7700.00 | Window Closed / Lapsed |