US4726990A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1986-11-06
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Granted: 1988-02-23
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Expires: 2006-11-06
Abstract
Abstract A coating type magnetic recording medium particuarly suitable as a mangetic disk is provided, which comprises a substrate and a magnetic layer of a plate magnetic powder and a binder on the substrate. Selection is made such that the plate magnetic powder has an average particle diameter of up to 0.2 μm and an average flakiness of at least 2, the magnetic layer is up to 1.8 μm thick, and the magnetic recording medium has a coercive force of a value x in Oe and a rectangular ratio Br/Bm of a value y both in a direction perpendicular to the magnetic layer surface, which fall in the range defined by the following equations: 400≦x≦800, y≦1, and 0.5≦y≦0.75 where 750≦x≦800, and 0.5≦y≦-0.001x+1.5 where 400≦x<750.
Inventors
- 👤 Toru Shimozawa
- 👤 Shigeyo Miyamori
- 👤 Masaharu Nishimatsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:28
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
122 words
A magnetic recording medium comprising a substrate having opposing major surfaces and a single magnetic layer on at least one major surface of the substrate consisting essentially of a plate magnetic powder having an average particle diameter of up to 0.2 μm and an average flakiness of at least 2 and a binder, the magnetic layer having a thickness of up to 1.8 μm, wherein the magnetic recording medium has a coercive force having a value x as expressed in oersted and a rectangular ratio having a value y both in a direction perpendicular to the surface of the magnetic layer, which fall in the range defined by the following equations: 400≦x≦800, y≦1, and 0.5≦y≦0.75 where 750≦x≦800, and 0.5≦y≦-0.001x +1.5 where 400≦x≦750.
Claim 2
Dependent Claim
122 words
A magnetic recording medium comprising a substrate having opposing major surfaces and a single magnetic layer on at least one major surface of the substrate consisting essentially of a plate magnetic powder having an average particle diameter of up to 0.2 μm and an average flakiness of at least 2 and a binder, the magnetic layer having a thickness of up to 1.8 μm, wherein the magnetic recording medium has a coercive force having a value x as expressed in oersted and a rectangular ratio having a value y both in a direction perpendicular to the surface of the magnetic layer, which fall in the range defined by the following equations: 400≦x≦800, y≦1, and 0.5≦y≦0.75 where 750≦x≦800, and 0.5≦y≦-0.001x +1.5 where 400≦x≦750.
Claim 3
Dependent Claim
29 words
The magnetic recording medium of claim 1 wherein the range of x and y is defined by the equations: 500≦x≦780, and 0.5≦y≦0.75 where 750≦x≦780, and 0.5≦y≦-0.001x +1.5 where 500≦x≦750.
Claim 4
Dependent Claim
14 words
The magnetic recording medium of claim 1 wherein the flakiness is at least 6.
Claim 5
Dependent Claim
16 words
The magnetic recording medium of claim 1 wherein the binder is comprised of a radiation-curable resin.
Claim 6
Dependent Claim
20 words
The magnetic recording medium of claim 1 wherein the single magnetic layer is on each major surface of the substrate.
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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) | 1991-02-22 | 1991-08-24 | 1992-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-22 | 1995-08-24 | 1996-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-22 | 1999-08-24 | 2000-02-23 | $7700.00 | Window Closed / Lapsed |