Patent US4526837A successfully refreshed from Google Patents.
US4526837A
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1981-08-28
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Granted: 1985-07-02
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Expires: 2001-08-28
Abstract
Abstract PCT No. PCT/JP81/00204 Sec. 371 Date Apr. 23, 1982 Sec. 102(e) Date Apr. 23, 1982 PCT Filed Aug. 28, 1981 PCT Pub. No. WO82/00914 PCT Pub. Date Mar. 18, 1982.This invention provides a magnetic recording medium with excellent electromagnetic characteristics and running durability. According to the invention, a magnetic powder is kneaded with a cross-linkable or polymerizable resin binder, together with a phosphoric ester having a polymerizable, unsaturated double bond or bonds, the resulting coating material is applied to a substrate, and then the coating is cross-linked or polymerized. The addition of the phosphoric ester in place of an ordinary dispersing agent improves the mechanical properties of the magnetic coating and the durability and running quality of the magnetic recording medium.
Inventors
- 👤 Akira Ohtsuki
- 👤 Ryozo Konno
- 👤 Makio Sugai
- 👤 Masaharu Nishimatsu
- 👤 Yuichi Kubota
- 👤 Kazushi Tanaka
- 👤 Osamu Shinoura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/7013; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
63 words
A magnetic recording medium comprising a substrate and a magnetic recording layer, said magnetic recording layer comprising a coating material containing a magnetic powder dispersed in a radiation cross-linked or radiation polymerized mixture of a resin binder, together with from 0.5 to 10 wt% based on the weight of magnetic powder, of a phosphoric ester having at least one polymerizable, unsaturated double bond.
Claim 2
Dependent Claim
63 words
A magnetic recording medium comprising a substrate and a magnetic recording layer, said magnetic recording layer comprising a coating material containing a magnetic powder dispersed in a radiation cross-linked or radiation polymerized mixture of a resin binder, together with from 0.5 to 10 wt% based on the weight of magnetic powder, of a phosphoric ester having at least one polymerizable, unsaturated double bond.
Claim 3
Dependent Claim
59 words
A magnetic recording medium according to claim 1, wherein said phosphoric ester having at least one polymerizable, unsaturated double bond is a product obtained by reacting a phosphoric ester of a compound having two or more hydroxyl groups with an acrylic or methacrylic compound having a functional group reactive with an isocyanate group and also with a polyisocyanate compound.
Claim 4
Dependent Claim
105 words
A magnetic recording medium according to claim 1, wherein said cross-linked or polymerized resin binder is a mixture of (A) a compound prepared by reacting a partly saponified vinyl chloride-vinyl acetate copolymer with a polyisocyanate compound and then reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group and (B) a compound prepared by reacting a polyol with a polyisocyanate compound and then reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group, in a mixing ratio of 20-95 wt% (A), to 5-80 wt% (B).
Claim 5
Dependent Claim
25 words
A magnetic recording medium according to claim 1, 2, or 3, wherein said magnetic powder consists of an acicular cobalt-modified iron oxide and/or alloy particles.
Claim 6
Dependent Claim
25 words
A magnetic recording medium according to claim 1, wherein said cross-linking or polymerization by exposure to radiation is carried on in an inert gas stream.
Claim 7
Dependent Claim
26 words
A magnetic recording medium according to claim 3, wherein the mixing ratio of A to B is 50 to 90 wt% (A) to 10-50 wt% (B).
References Cited (Backward Citations)
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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) | 1988-07-01 | 1988-12-31 | 1989-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-01 | 1992-12-31 | 1993-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-01 | 1996-12-31 | 1997-07-02 | $7700.00 | Window Closed / Lapsed |