US4521486A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Sony Corp
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Filing: 1982-07-08
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Granted: 1985-06-04
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Expires: 2002-07-08
Abstract
Abstract The magnetic recording medium comprises a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder. The binder contains a binder component having an absorbed amount of the binder component to a surface of the magnetic powder more than 1.5 mg per square meter of a surface area of the powder measured in 3 weight % solution in methyl ethyl ketone solvent, and the magnetic layer has a pigment volume concentration of the magnetic powder between 60 and 75%. The binder provides an improved strength and high pigment volume concentration of magnetic coating layer, and improved durability of the magnetic recording medium.
Inventors
- 👤 Yoshinobu Ninomiya
- 👤 Masashi Somezawa
- 👤 Akira Hashimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:29
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7021; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2998; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
82 words
A magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder, said binder containing a binder component being adsorbed on a surface of said magnetic powder in an amount more than 1.5 mg per square meter of the surface area of said powder measured in 3 weight % solution in methyl ethyl ketone solvent, and said magnetic layer having a pigment volume concentration of said magnetic powder between 60 and 75%.
Claim 2
Dependent Claim
82 words
A magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder, said binder containing a binder component being adsorbed on a surface of said magnetic powder in an amount more than 1.5 mg per square meter of the surface area of said powder measured in 3 weight % solution in methyl ethyl ketone solvent, and said magnetic layer having a pigment volume concentration of said magnetic powder between 60 and 75%.
Claim 3
Dependent Claim
25 words
A magnetic recording medium according to claim 1, in which said binder component is more than 20 weight % of total amount of said binder.
Claim 4
Dependent Claim
29 words
A magnetic recording medium according to claim 1, in which said binder component is polyurethane resin or polyurethane resin having a hydrophilic group in the molecule of said resins.
Claim 5
Dependent Claim
21 words
A magnetic recording medium according to claim 3, in which said hydrophilic group is a sulfonic group or sulfonic salt group.
Claim 6
Dependent Claim
26 words
A magnetic recording medium according to claim 3, in which said hydrophilic group is contained in said resin in an amount between 0.01 and 2.0 mmol/g.
Claim 7
Dependent Claim
25 words
A magnetic recording medium according to claim 1, in which said binder component is polyurethane resin having more than 2 hydroxy groups in one molecule.
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) | 1988-06-03 | 1988-12-03 | 1989-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-03 | 1992-12-03 | 1993-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-03 | 1996-12-03 | 1997-06-04 | $7700.00 | Window Closed / Lapsed |