US4582754A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1984-07-26
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Granted: 1986-04-15
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Expires: 2004-07-26
Abstract
Abstract A magnetic recording medium comprising a support having provided thereon a magnetic recording layer containing (1) a cobalt-containing iron oxide, (2) graphite, and (3) a copolymer of vinyl chloride, vinyl acetate and maleic acid.
Inventors
- 👤 Katsumi Ryoke
- 👤 Shinobu Iida
- 👤 Masaaki Fujiyama
- 👤 Eiichi Tadokoro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:13
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7023; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70668; G11B5/70673; G11B5/708; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
80 words
A magnetic recording medium comprising a support having provided thereon a magnetic recording layer containing (1) a cobalt-containing iron oxide, (2) 0.1 to 20 parts by weight per 100 parts by weight of the cobalt-containing iron oxide of graphite having a specific surface area of about 100 to 800 m 2 /g, and (3) a copolymer comprising at least about 70 mol% of vinyl chloride, 1 to 30 mol% of vinyl acetate and about 0.5 to 10 mol% maleic acid.
Claim 2
Dependent Claim
80 words
A magnetic recording medium comprising a support having provided thereon a magnetic recording layer containing (1) a cobalt-containing iron oxide, (2) 0.1 to 20 parts by weight per 100 parts by weight of the cobalt-containing iron oxide of graphite having a specific surface area of about 100 to 800 m 2 /g, and (3) a copolymer comprising at least about 70 mol% of vinyl chloride, 1 to 30 mol% of vinyl acetate and about 0.5 to 10 mol% maleic acid.
Claim 3
Dependent Claim
47 words
The magnetic recording medium as claimed in claim 1, wherein the cobalt-containing iron oxide is cobalt-containing γ-Fe 2 O 3 , cobalt-containing γ-Fe 3 O 4 or a cobalt-containing iron oxide having a degree of oxidation between γ-Fe 2 O 3 and γ-Fe 3 O 4 .
Claim 4
Dependent Claim
29 words
The magnetic recording medium as claimed in claim 1, wherein the cobalt containing iron oxide has a specific surface area of from about 10 to 50 m 2 /g.
Claim 5
Dependent Claim
27 words
The magnetic recording medium as claimed in claim 1, wherein cobalt containing iron oxide has a specific surface area of from 20 to 40 m 2 /g.
Claim 6
Dependent Claim
27 words
The magnetic recording medium as claimed in claim 1, wherein the amount of cobalt-containing iron oxide is 0.5 to 10 weight% per 100 weight% of iron oxide.
Claim 7
Dependent Claim
25 words
The magnetic recording medium as claimed in claim 1, wherein the average particle size of the graphite is not more than about 5 microns (μm).
Claim 8
Dependent Claim
28 words
The magnetic recording medium as claimed in claim 1, wherein the graphite has at least about 92% fixed carbon and not more than about 3% of ash content.
Claim 9
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1 wherein the average polymerization degree of the copolymer is about 200 to 600.
Claim 10
Dependent Claim
17 words
The magnetic recording medium as claimed in claim 1, wherein said magnetic recording layer contains an abrasive.
Claim 11
Dependent Claim
18 words
The magnetic recording medium as claimed in claim 9 wherein said abrasive is α-Al 2 O 3 .
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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) | 1989-04-14 | 1989-10-14 | 1990-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-14 | 1993-10-14 | 1994-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-14 | 1997-10-14 | 1998-04-15 | $7700.00 | Window Closed / Lapsed |