US4677023A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1985-05-30
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Granted: 1987-06-30
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Expires: 2005-05-30
Abstract
Abstract A magnetic recording medium comprising a non-magnetic substrate, a ferromagnetic thin film formed on the substrate, and a top coating layer containing a fine particulate pigment, formed on the surface of the ferromagnetic thin film, wherein the top coating layer satisfies the condition of 0.3x<y<2x where x is the average particle size of the fine particulate pigment and y is the thickness of the top coating layer, and the average particle size x is less than 200 Å.
Inventors
- 👤 Hideki Ishizaki
- 👤 Osamu Hasegawa
- 👤 Masaharu Nishimatsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/259; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
90 words
A magnetic recording medium comprising a non-magnetic substrate, a ferromagnetic metal or metal alloy thin film formed on the substrate, and a top coating layer contained a fine particulate pigment, formed on the surface of the ferromagnetic thin film, the opposite surface of said top coating layer being exposed, wherein the top coating layer satisifies the condition of 0.3x<y<2x where is the average particle size of the particlate pigment and y is the thickness of the top coating layer, and the average particle size x is less than 200 Å.
Claim 2
Dependent Claim
90 words
A magnetic recording medium comprising a non-magnetic substrate, a ferromagnetic metal or metal alloy thin film formed on the substrate, and a top coating layer contained a fine particulate pigment, formed on the surface of the ferromagnetic thin film, the opposite surface of said top coating layer being exposed, wherein the top coating layer satisifies the condition of 0.3x<y<2x where is the average particle size of the particlate pigment and y is the thickness of the top coating layer, and the average particle size x is less than 200 Å.
Claim 3
Dependent Claim
22 words
The magnetic recording medium according to claim 1, wherein the top coating layer has a thickness of not greater than 450 Å.
Claim 4
Dependent Claim
65 words
The magnetic recording medium according to claim 1, wherein the fine particulate pigment is selected from the group consisting of ZrO 2 , Cr 2 O 3 , Al 2 O 3 , Y 2 O 3 , CeO 2 , Fe 3 O 4 , Fe 2 O 3 , ZrSiO 4 , Sb 2 O 5 , SnO 2 and TiO 2 .
Claim 5
Dependent Claim
24 words
The magnetic recording medium according to claim 1, wherein the average particle size of the fine particulate pigment is not larger than 150 Å.
Claim 6
Dependent Claim
32 words
The magnetic recording medium according to claim 1, wherein the top coating layer contains carbon black in a weight ratio of carbon black to fine particulate pigment of from 1/9 to 8/2.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-29 | 1990-12-29 | 1991-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-29 | 1994-12-29 | 1995-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-29 | 1998-12-29 | 1999-06-30 | $7700.00 | Window Closed / Lapsed |