Patent US4844978A successfully refreshed from Google Patents.
US4844978A
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US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1985-11-06
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Granted: 1989-07-04
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Expires: 2005-11-06
Abstract
Abstract In a magnetic recording medium comprising a substrate, a ferromagnetic metal thin film formed on the substrate, and a topcoat formed on the thin film, the topcoat is a plasma-polymerized film containing carbon and hydrogen in an atomic ratio of C/H of from 1 to 6, and having a thickness of 10 to 40 angstroms and a contact angle with water in the range of from 60° to 130°.
Inventors
- 👤 Masatoshi Nakayama
- 👤 Yasufumi Takasugi
- 👤 Kunihiro Ueda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:33
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/3154; Y10T428/31544; Y10T428/31678; Y10T428/31692; Y10T428/31699; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
160 words
In a magnetic recording medium comprising a substrate, a ferromagnetic metal thin film formed on the substrate, and a topcoat formed on the thin film, the improvement wherein the topcoat comprises a plasma-polymerized film consisting of essentially of carbon, hydrogen, and fluorine, the atomic ratio of carbon to hydrogen being from 2:1 to 8:1 and the atomic ratio of fluorine to hydrogen being from 1.0:1.0 to 3.0:1.0 and said plasma-polymerized film being prepared by activating a gaseous reactant to a plasma to generate active species thereof while feeding the reactant into a plasma zone with W/F·M set to 10 7 to 10 12 joule/kg wherein W is an input power applied for plasma generation, F is the flow rate of the gas reactant, and M is the molecular weight of the gas reactant, whereby the polymerized film has a thickness of from 10 to 40 angstrom and a contact angle with water in the range of from 100° to 130°.
Claim 2
Dependent Claim
160 words
In a magnetic recording medium comprising a substrate, a ferromagnetic metal thin film formed on the substrate, and a topcoat formed on the thin film, the improvement wherein the topcoat comprises a plasma-polymerized film consisting of essentially of carbon, hydrogen, and fluorine, the atomic ratio of carbon to hydrogen being from 2:1 to 8:1 and the atomic ratio of fluorine to hydrogen being from 1.0:1.0 to 3.0:1.0 and said plasma-polymerized film being prepared by activating a gaseous reactant to a plasma to generate active species thereof while feeding the reactant into a plasma zone with W/F·M set to 10 7 to 10 12 joule/kg wherein W is an input power applied for plasma generation, F is the flow rate of the gas reactant, and M is the molecular weight of the gas reactant, whereby the polymerized film has a thickness of from 10 to 40 angstrom and a contact angle with water in the range of from 100° to 130°.
Claim 3
Dependent Claim
56 words
The magnetic recording medium of claim 1, wherein the atomic ratio of fluorine to hydrogen measured at the top surface of the topcoat is higher than that measured at a level in the topcoat spaced one-third of its total thickness from its surface adjacent the ferromagnetic metal thin film by a factor of at least 1.5.
Claim 4
Dependent Claim
20 words
The magnetic recording medium of claim 1, wherein the ferromagnetic metal thin film is a cobalt base metal thin film.
Claim 5
Dependent Claim
15 words
The magnetic recording medium of claim 3, wherein the ferromagnetic metal thin film contains oxygen.
Claim 6
Dependent Claim
20 words
The magnetic recording medium of claim 1, wherein the said polymerized film has a thickness of 15 to 30 Å.
Claim 7
Dependent Claim
21 words
The magnetic recording medium of claim 1, wherein the said atomic ratio of carbon to hydrogen is from 3:1.0 to 5:1.0.
Claim 8
Dependent Claim
20 words
The magnetic recording medium of claim 1, wherein the atomic ratio of fluorine to hydrogen is from 1.11:1.0 to 2.0:1.0.
Claim 9
Dependent Claim
17 words
The magnetic recording medium of claim 2, wherein the said factor is from 1.5:1.0 to 3.0:1 0.
Claim 10
Dependent Claim
26 words
The magnetic recording medium of claim 1, wherein the said polymerized film has a contact angle with water in the range of from 110° to 120°.
Claim 11
Dependent Claim
17 words
The magnetic recording medium of claim 1, wherein the ferromagnetic metal thin film comprises cobalt and nickel.
Claim 12
Dependent Claim
18 words
The magnetic recording medium of claim 1, wherein the ferromagnetic metal thin film comprises cobalt, nickel, and oxygen.
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) | 1992-07-03 | 1993-01-02 | 1993-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-03 | 1997-01-02 | 1997-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-03 | 2001-01-02 | 2001-07-04 | $7700.00 | Window Closed / Lapsed |