Patent US4536444A successfully refreshed from Google Patents.
US4536444A
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Magnetic recording medium
Assignee: Maxell Ltd
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Filing: 1984-11-16
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Granted: 1985-08-20
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Expires: 2004-11-16
Abstract
Abstract A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group, which has improved durability and corrosion resistivity.
Inventors
- 👤 Kenji Sumiya
- 👤 Fumio Togawa
- 👤 Osamu Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:50
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/722; G11B5/68; G11B5/70; G11B5/706; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/31504; Y10T428/3154; Y10T428/31544
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
44 words
A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group.
Claim 2
Dependent Claim
44 words
A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group.
Claim 3
Dependent Claim
82 words
A magnetic recording medium according to claim 1, wherein the perfluroalkyl polyether derivative having a phosphate terminal group is a compound of the formula: ##STR5## wherein A is a group of the formula: --[CF(CF.sub.3)--CF.sub.2 O]--, --(CF.sub.2 CF.sub.2 O)-- or --(CF.sub.2 O)-- B is a group of the formula: --(CF.sub.2 COO)-- or --[CF(CF.sub.3)--COO]-- X is hydrogen or fluorine, R is hydrogen, fluorine, methyl, trifluoromethyl or chloromethyl, n is an integer of 10 to 50 and m is an integer of 1 to 50.
Claim 4
Dependent Claim
32 words
A magnetic recording medium according to claim 1, wherein an amount of the perfluroalkyl polyether derivative having a phosphate terminal group to be coated is from 0.01 to 30 mg/m 2 .
Claim 5
Dependent Claim
14 words
A magnetic recording medium according to claim 1, wherein the substrate is a tape.
Claim 6
Dependent Claim
14 words
A magnetic recording medium according to claim 1, wherein the substrate is a disc.
Claim 7
Dependent Claim
14 words
A magnetic recording medium according to claim 1, wherein the substrate is a drum.
Claim 8
Dependent Claim
16 words
A magnetic recording medium according to claim 1, wherein the substrate is made of polyethylene terephthalate.
Claim 9
Dependent Claim
16 words
A magnetic recording medium according to claim 1, wherein the magnetic layer comprises metallic magnetic powder.
Claim 10
Dependent Claim
27 words
A magnetic recording medium according to claim 8, wherein the metallic magnetic powder is selected from the group consisting of Fe powder, Co powder and Fe-Ni powder.
Claim 11
Dependent Claim
17 words
A magnetic recording medium according to claim 1, wherein the magnetic layer comprises a ferromagnetic thin film.
Claim 12
Dependent Claim
27 words
A magnetic recording material according to claim 10, wherein the ferromagnetic material is selected from the group consisting of Co, Ni, Fe, Co-Ni, Co-Cr, Co-P and Co-Ni-P.
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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) | 1988-08-19 | 1989-02-18 | 1989-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-19 | 1993-02-18 | 1993-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-19 | 1997-02-18 | 1997-08-20 | $7700.00 | Window Closed / Lapsed |