Patent US4846815A successfully refreshed from Google Patents.
US4152485A
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US
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Magnetic recording medium
Assignee: Toyobo Co Ltd
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Filing: 1978-07-27
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Granted: 1979-05-01
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Expires: 1998-07-27
Abstract
Abstract A magnetic recording medium having a high ratio of the residual magnetization (Br) to the saturation magnetization (Bm) and decreased voids, which has a magnetizable layer of magnetic particles which are dispersed in a binder: a polyester or polyurethane having a metal sulfonate group of 10 to 1,000 equivalents/106 g of the polymer, preferably a polyester having a reduced viscosity of 0.2 or more and having a metal sulfonate group of 20 to 300 equivalents/106 g of the polyester; a polyester having a reduced viscosity of less than 0.2 and having a metal sulfonate group of 20 to 500 equivalents/106 g of the polyester; or a polyurethane having a metal sulfonate group of 20 to 400 equivalents/106 g of the polyurethane. Said magnetic recording medium is particularly suitable for an electronic computer tape and video tape.
Inventors
- 👤 Yutaka Mizumura
- 👤 Nobuyuki Hiura
- 👤 Hideo Miyake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:21
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7021; C; C08; C08G; C08G18/00; C08G18/06; C08G18/08; C08G18/0804; C08G18/0819; C08G18/0828; C08G18/28; C08G18/40; C08G18/42; C08G18/46; C08G18/4676; G11B5/7022; G11B5/7023; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31551; Y10T428/31565; Y10T428/31573; Y10T428/31576; Y10T428/3158; Y10T428/31609; Y10T428/31786
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
43 words
A magnetic recording medium having a magnetizable layer of fine magnetic particles which are dispersed in a binder selected from the group consisting of a polyester and polyurethane having a metal sulfonate group of 10 to 1000 equivalents/10 6 g of the polymer.
Claim 2
Dependent Claim
43 words
A magnetic recording medium having a magnetizable layer of fine magnetic particles which are dispersed in a binder selected from the group consisting of a polyester and polyurethane having a metal sulfonate group of 10 to 1000 equivalents/10 6 g of the polymer.
Claim 3
Dependent Claim
48 words
A magnetic recording medium according to claim 1, wherein the binder is a polyester having a reduced viscosity of 0.2 or more which is copolymerized with a dicarboxylic acid component having a metal sulfonate group of 0.3 to 7.0% by mol based on the total carboxylic acid components.
Claim 4
Dependent Claim
34 words
A magnetic recording medium according to claim 2, wherein the polyester having a reduced viscosity of 0.2 or more has a metal sulfonate group of 20 to 300 equivalents/10 6 g of the polyester.
Claim 5
Dependent Claim
57 words
A magnetic recording medium according to claim 1, wherein the binder is a mixture of a polyester having a reduced viscosity of less than 0.2 which is copolymerized with a dicarboxylic acid component having a metal sulfonate group of at least 0.5% by mol based on the total carboxylic acid components and other thermoplastic and/or thermosetting resin.
Claim 6
Dependent Claim
34 words
A magnetic recording medium according to claim 4, wherein the polyester having a reduced viscosity of less than 0.2 has a metal sulfonate group of 20 to 500 equivalents/10 6 g of the polyester.
Claim 7
Dependent Claim
29 words
A magnetic recording medium according to claim 1, wherein the binder is a polyurethane having a metal sulfonate group of 20 to 400 equivalents/10 6 g of the polyurethane.
Claim 8
Dependent Claim
26 words
A magnetic recording medium according to claim 6, wherein the polyurethane is prepared by reacting a polyester polyol having a metal sulfonate group and a polyisocyanate.
Claim 9
Dependent Claim
47 words
A magnetic recording medium according to claim 1, wherein the polyester and polyurethane contain a dicarboxylic acid component having an alkali metal sulfonate group selected from the group consisting of alkali metal salts of 4-sulfophthalic acid, 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, and 5-(4-sulphenoxy)terephthalic acid.
Claim 10
Dependent Claim
41 words
A magnetic recording medium according to claim 8, wherein the dicarboxylic acid component having an alkali metal sulfonate group is a member selected from the group consisting of 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, sodium sulfoterephthalic acid, and potassium sulfoterephthalic acid.
Claim 11
Dependent Claim
17 words
A magnetic recording medium according to claim 1, wherein an isocyanate compound is incorporated into the binder.
Claim 12
Dependent Claim
31 words
A magnetic recording medium according to claim 1, wherein both the polyester having a metal sulfonate group and the polyurethane having a metal sulfonate group are used together as the binder.
Claim 13
Dependent Claim
21 words
A magnetic recording medium according to claim 1 or 11, wherein a vinyl chloride-vinyl acetate copolymer is incorporated into the binder.
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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) | 1982-04-30 | 1982-10-30 | 1983-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-30 | 1986-10-30 | 1987-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-30 | 1990-10-30 | 1991-05-01 | $7700.00 | Window Closed / Lapsed |