Patent US4584243A successfully refreshed from Google Patents.
US4584243A
Expired / Lapsed
US
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Abrasive, production thereof and use thereof in magnetic recording medium
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1983-10-25
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Granted: 1986-04-22
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Expires: 2003-10-25
Abstract
Abstract When an abrasive having an oleophilic surface used in a magnetic recording medium obtained by subjecting an inorganic powder having a Mohs hardness of 5 or above and an average particle size of 2 mu m across or below to a dry contact treatment with a dispersing agent having an oleophilic group under grinding conditions giving an impact value of 1 G or greater is used in combination with a magnetic powder as a magnetic recording layer of magnetic recording medium, the wear at a magnetic head can be prevented and still characteristics can be improved.
Inventors
- 👤 Hidekimi Kadokura
- 👤 Hiroshi Umezaki
- 👤 Hideaki Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:10
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; C; C09; C09K; C09K3/00; C09K3/14; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993; Y10T428/2995; Y10T428/2996; Y10T428/2998
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
114 words
In a magnetic recording medium comprising a support and a magnetic recording layer coated thereon, the improvement wherein the magnetic recording layer comprises, per 100 parts by weight of a magnetic powder, 0.1 to 15 parts by weight of an abrasive having an oleophilic surface obtained by subjecting 100 parts by weight of an inorganic powder having a Mohs hardness of 5 or above and an average particle size of 0.1 to 2 μm across to a dry contact treatment with 0.01 to 20 parts by weight of a dispersing agent having an olephilic group under grinding conditions imparting an impact value of IG or greater prior to the mixing with the magnetic powder.
Claim 2
Dependent Claim
114 words
In a magnetic recording medium comprising a support and a magnetic recording layer coated thereon, the improvement wherein the magnetic recording layer comprises, per 100 parts by weight of a magnetic powder, 0.1 to 15 parts by weight of an abrasive having an oleophilic surface obtained by subjecting 100 parts by weight of an inorganic powder having a Mohs hardness of 5 or above and an average particle size of 0.1 to 2 μm across to a dry contact treatment with 0.01 to 20 parts by weight of a dispersing agent having an olephilic group under grinding conditions imparting an impact value of IG or greater prior to the mixing with the magnetic powder.
Claim 3
Dependent Claim
50 words
A magnetic recording medium according to claim 1, wherein the inorganic powder is a compound selected from the group consisting of metal oxides and metal double oxides, including γ-alumina, α-alumina, silica, iron oxide, chromium oxide, titanium oxide, zirconium oxide, cerium oxide, tin oxide, silicon carbide, spinel, zinc aluminate and aluminosilicate.
Claim 4
Dependent Claim
60 words
A magnetic recording medium according to claim 1, wherein the dispersing agent is sodium octandeconate, aluminum dodecanoate, aluminum octadeconate, sodium dodecylsulfate, sodium dodecylbenzenesulfonate, sodium octadecylbenzenesulfonate, D-2-ethylhexyl sodium sulfosuccinate, sodium polyoxyethylene dodecyl ether sulfate, polyoxyethylene dodecyl ether, sorbitan monododecanoate, dodecylamine acetate, soybean lecithin, sodium dodecanoate, γ-aminopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dodecanoic acid, ammonium dodecanoate, ammonium octadecanoate, ocatadecanoic acid, oleic acid, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-mercaptopropropyltrimethoxysilane.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-04-21 | 1989-10-21 | 1990-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-21 | 1993-10-21 | 1994-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-21 | 1997-10-21 | 1998-04-22 | $7700.00 | Window Closed / Lapsed |