Patent US4448843A successfully refreshed from Google Patents.
US4448843A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1981-04-10
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Granted: 1984-05-15
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Expires: 2001-04-10
Abstract
Abstract A magnetic recording medium is described wherein a layer comprising mainly a polyurethane resin, vinylidene chloride copolymer, or a cellulose derivative is formed on the surface of a vapor-deposited ferromagnetic metal layer on a substrate.
Inventors
- 👤 Yasuyuki Yamada
- 👤 Ryuji Shirahata
- 👤 Akio Yanai
- 👤 Tatsuji Kitamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:32
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31551; Y10T428/31605; Y10T428/31678; Y10T428/31692; Y10T428/31699; Y10T428/31703
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
63 words
A magnetic recording medium comprising (a) a support, (b) a vapor-deposited ferromagnetic metal layer on said support(a), and (c) a protective layer comprising mainly one of (i) a polyurethane resin, (ii) a vinylidene chloride copolymer or (iii) a cellulose derivative on the surface of said vapor-deposited ferromagnetic metal layer (b), said protective layer having a thickness of from about 0.002 to 0.3 μm.
Claim 2
Dependent Claim
63 words
A magnetic recording medium comprising (a) a support, (b) a vapor-deposited ferromagnetic metal layer on said support(a), and (c) a protective layer comprising mainly one of (i) a polyurethane resin, (ii) a vinylidene chloride copolymer or (iii) a cellulose derivative on the surface of said vapor-deposited ferromagnetic metal layer (b), said protective layer having a thickness of from about 0.002 to 0.3 μm.
Claim 3
Dependent Claim
23 words
A magnetic recording medium as in claim 1, wherein the protective layer (c) has a thickness of from about 0.005 to 0.2 μm.
Claim 4
Dependent Claim
47 words
A magnetic recording medium as in claim 1, or 2, wherein the protective layer (c) comprises mainly a polyurethane, and from 0.2 to 30 wt% of a vinylidene chloride copolymer or cellulose derivative, based on the total weight of the protective layer, as an additional component thereof.
Claim 5
Dependent Claim
33 words
A magnetic recording medium as in claim 1, or 2 wherein the protective layer (c) comprises mainly a polyurethane resin having an average molecular weight in the range of from 5,000 to 500,000.
Claim 6
Dependent Claim
18 words
A magnetic recording medium as in claim 4, wherein the average molecular weight is from 10,000 to 200,000.
Claim 7
Dependent Claim
29 words
A magnetic recording medium as in claim 1, or 3, wherein the protective layer (c) comprises mainly a vinylidene chloride copolymer comprising from 98 to 60 wt% vinylidene chloride.
Claim 8
Dependent Claim
21 words
A magnetic recording medium as in claim 6, wherein the vinylidene chloride copolymer comprises from 95 to 70 wt% vinylidene chloride.
Claim 9
Dependent Claim
18 words
A magnetic recording medium as in claim 1, or 2, wherein the protective layer (c) contains a lubricant.
Claim 10
Dependent Claim
26 words
A magnetic recording medium as in claim 1, or 2, comprising a primer layer (d) between the ferromagnetic metal layer (b) and the protective layer (c).
References Cited (Backward Citations)
US4260466A
Cited
JPS5320204A
Cited
DE2915905A1
Cited
US4241139A
Cited
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Cited
US4309482A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |