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Patent US4701372A successfully refreshed from Google Patents.
US4701372A
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Magnetic recording medium
Assignee: Toyobo Co Ltd
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Filing: 1986-09-09
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Granted: 1987-10-20
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Expires: 2006-09-09
Abstract
Abstract A magnetic recording medium characterized by a magnetic layer comprising (A) magnetic fine particles of plate-like hexagonal ferrite having a particle size of 0.3 microns or less and an easily magnetizable axis in the direction vertical to the flat plate surface (B) a polyurethane resin having a metal sulfonate group and (C) one or more esters of C 10 -C 18 fatty acids with alcohols having not more than 15 carbon atoms.
Inventors
- 👤 Takashi Akiyama
- 👤 Yasunari Hotta
- 👤 Naonobu Oda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:11
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/71; C; C08; C08G; C08G18/00; C08G18/06; C08G18/08; C08G18/0804; C08G18/0819; C08G18/0828; G11B5/702; G11B5/7021; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
104 words
A magnetic recording medium which comprises applying a magnetic layer containing (A) magnetic fine particles of plate-like hexagonal ferrite having a particle size of 0.3 μm or less and an easy axis for magnetization in the direction vertical to the flat plate surface, (B) a polyurethane resin having a metal sulfonate group of 20 to 500 equivalents/10 6 g of the polymer and (C) one or more members selected from the esters of C 10 -C 18 fatty acids with alcohols having not more than 15 carbon atoms, the ratio of (C) to (A) being 0.1 to 20 wt. %, to a non-magnetic substrate.
Claim 2
Dependent Claim
104 words
A magnetic recording medium which comprises applying a magnetic layer containing (A) magnetic fine particles of plate-like hexagonal ferrite having a particle size of 0.3 μm or less and an easy axis for magnetization in the direction vertical to the flat plate surface, (B) a polyurethane resin having a metal sulfonate group of 20 to 500 equivalents/10 6 g of the polymer and (C) one or more members selected from the esters of C 10 -C 18 fatty acids with alcohols having not more than 15 carbon atoms, the ratio of (C) to (A) being 0.1 to 20 wt. %, to a non-magnetic substrate.
Claim 3
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 1, wherein the magnetic layer contains (C) and (A) in a (C):(A) weight ratio of from 1.0 to 7.0 wt. %.
Claim 4
Dependent Claim
46 words
A magnetic recording medium as claimed in claim 1, wherein the magnetic layer contains non-magnetic fine particles having a Mohs' hardness of 6 or more and a particle size of 1.0 μm or less in a weight ratio to (A) of 2 to 20 wt. %.
Claim 5
Dependent Claim
20 words
A magnetic recording medium as claimed in claim 1, wherein said magnetic recording medium is a flexible and disc-like one.
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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) | 1990-10-19 | 1991-04-20 | 1991-10-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-19 | 1995-04-20 | 1995-10-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-19 | 1999-04-20 | 1999-10-20 | $7700.00 | Window Closed / Lapsed |