US4420531A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1981-09-17
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Granted: 1983-12-13
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Expires: 2001-09-17
Abstract
Abstract A magnetic recording medium is composed of a base and a magnetic coating which comprises a binder and a magnetic powder dispersed therein. The magnetic powder, in turn, contains a nonmagnetic powder having an average particle size of not more than 2 μm and a hardness of at least 6 on Mohs scale, in an amount of 1-20% on the basis of the weight of the magnetic powder, and the binder contains a resin such as polyester resin having a group expressed by the formula --SO 3 M where M is monovalent metal such as Na.
Inventors
- 👤 Fuminori Tokuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:29
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
98 words
A magnetic recording medium composed of a base and a magnetic coating formed thereon and comprising a binder and a magnetic powder dispersed in the binder, characterized in that said magnetic powder contains a nonmagnetic powder having an average particle size of not more than 2 μm and a Mohs hardness of at least 6, in an amount of 1 to 20% on the basis of the weight of the magnetic powder, and said binder contains a dispersant resin having a functional group attached thereto expressed by the formula --SO 3 M where M is a monovalent metal.
Claim 2
Dependent Claim
98 words
A magnetic recording medium composed of a base and a magnetic coating formed thereon and comprising a binder and a magnetic powder dispersed in the binder, characterized in that said magnetic powder contains a nonmagnetic powder having an average particle size of not more than 2 μm and a Mohs hardness of at least 6, in an amount of 1 to 20% on the basis of the weight of the magnetic powder, and said binder contains a dispersant resin having a functional group attached thereto expressed by the formula --SO 3 M where M is a monovalent metal.
Claim 3
Dependent Claim
15 words
A magnetic recording medium according to claim 1, wherein said group is --SO 3 Na.
Claim 4
Dependent Claim
17 words
A magnetic recording medium according to claim 1 or 2, wherein said dispersant resin is polyester resin.
Claim 5
Dependent Claim
23 words
A magnetic recording medium according to claim 1, wherein said dispersant resin is a polyester resin having a molecular weight of about 20,000.
Claim 6
Dependent Claim
100 words
A magnetic recording medium composed of a base and a magnetic coating formed thereon and comprising a binder and a magnetic powder dispersed in the binder, characterized in that said magnetic powder contains a nonmagnetic powder having an average particle size of not more than 2 μm and a Mohs hardness of at least 6, in an amount of 1 to 20% on the basis of the weight of the magnetic powder, and said binder contains a dispersant polyester resin having a molecular weight of about 20,000 and a functional group attached thereto expressed by the formula --SO 3 Na.
Claim 7
Dependent Claim
100 words
A magnetic recording medium composed of a base and a magnetic coating formed thereon and comprising a binder and a magnetic powder dispersed in the binder, characterized in that said magnetic powder contains a nonmagnetic powder having an average particle size of not more than 2 μm and a Mohs hardness of at least 6, in an amount of 1 to 20% on the basis of the weight of the magnetic powder, and said binder contains a dispersant polyester resin having a molecular weight of about 20,000 and a functional group attached thereto expressed by the formula --SO 3 Na.
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) | 1986-12-12 | 1987-06-13 | 1987-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-12 | 1991-06-13 | 1991-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-12 | 1995-06-13 | 1995-12-13 | $7700.00 | Window Closed / Lapsed |