US4624892A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1985-07-01
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Granted: 1986-11-25
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Expires: 2005-07-01
Abstract
Abstract A magnetic recording medium comprising a magnetic recording layer formed on one major surface of a non-magnetic substrate and a topcoat layer formed on the magnetic layer is characterized in that the topcoat layer contains a submicron particulate pigment observable under an electron microscope to have a linear distribution density of 10 to 1,000 per linear 100 μm and a particle size of less than 200 Å whereby the topcoat layer has a surface roughness R20 of not more than 400 Å.
Inventors
- 👤 Hideki Ishizaki
- 👤 Hiroyuki Arioka
- 👤 Toshiaki Ide
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:44
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/728; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/259
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
88 words
In a magnetic recording medium comprising a non-magnetic substrate having opposed major surfaces, a magnetic recording layer formed on one major surface of the substrate, and a topcoat layer formed on the magnetic layer, the improvement wherein the topcoat layer contains a submicron particulate pigment observable under an electron microscope to have a linear distribution density of 10 to 1,000 per linear 100 μm and a particle size of less than 200 Å whereby the topcoat layer has a surface roughness R20 of not more than 400 Å.
Claim 2
Dependent Claim
88 words
In a magnetic recording medium comprising a non-magnetic substrate having opposed major surfaces, a magnetic recording layer formed on one major surface of the substrate, and a topcoat layer formed on the magnetic layer, the improvement wherein the topcoat layer contains a submicron particulate pigment observable under an electron microscope to have a linear distribution density of 10 to 1,000 per linear 100 μm and a particle size of less than 200 Å whereby the topcoat layer has a surface roughness R20 of not more than 400 Å.
Claim 3
Dependent Claim
16 words
A magnetic recording medium according to claim 1 wherein the topcoat layer contains an organic binder.
Claim 4
Dependent Claim
14 words
A magnetic recording medium according to claim 2 wherein the binder is radiation curable.
Claim 5
Dependent Claim
15 words
A magnetic recording medium according to claim 1 wherein the topcoat layer contains an antioxidant.
Claim 6
Dependent Claim
20 words
A magnetic recording medium according to claim 1 wherein the topcoat layer has a thickness of 5 to 800 Å.
Claim 7
Dependent Claim
20 words
A magnetic recording medium according to claim 5 wherein the topcoat layer has a thickness of 5 to 450 Å.
Claim 8
Dependent Claim
20 words
A magnetic recording medium according to claim 5 wherein the topcoat layer has a thickness of 10 to 300 Å.
Claim 9
Dependent Claim
21 words
A magnetic recording medium according to claim 1 wherein the pigment particulates have a particle size of 20 to 200 Å.
Claim 10
Dependent Claim
67 words
A magnetic recording medium according to claim 1 wherein the pigment is selected from the group consisting of SiO 2 , TiO 2 , 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 , and SnO 2 .
Claim 11
Dependent Claim
14 words
A magnetic recording medium according to claim 9 wherein the pigment is colloidal silica.
Claim 12
Dependent Claim
14 words
A magnetic recording medium according to claim 9 wherein the pigment is colloidal titania.
Claim 13
Dependent Claim
15 words
A magnetic recording medium according to claim 9 wherein the pigment is pyrolyzed chromium oxide.
Claim 14
Dependent Claim
14 words
A magnetic recording medium according to claim 9 wherein the pigment is pyrolyzed silica.
Claim 15
Dependent Claim
19 words
A magnetic recording medium according to claim 1 wherein the magnetic recording layer comprises ferromagnetic particles in a binder.
Claim 16
Dependent Claim
19 words
A magnetic recording medium according to claim 1 wherein the magnetic recording layer is a ferromagnetic thin metal film.
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) | 1989-11-24 | 1990-05-26 | 1990-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-24 | 1994-05-26 | 1994-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-24 | 1998-05-26 | 1998-11-25 | $7700.00 | Window Closed / Lapsed |