Patent US4721640A successfully refreshed from Google Patents.
US4721640A
Expired / Lapsed
US
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Flexible magnetic disk sheet
Assignee: Fujifilm Holdings Corp
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Filing: 1984-11-21
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Granted: 1988-01-26
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Expires: 2004-11-21
Abstract
Abstract A flexible magnetic disk sheet including a central circular hole is described, having a protective layer on a surface portion surrounding the edge of the central circular hole, comprising the protective layer prepared by coating (a) a compound having an acrylate bond or a methacrylate bond at the end of at least one of a main chain and a side chain of molecules thereof, and (b) a solid lubricating agent, and exposing to radiation thereon for polymerizing and hardening it.
Inventors
- 👤 Mikihiko Kato
- 👤 Shigeo Komine
- 👤 Kazuhiko Morita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:34
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/725; G11B5/74; G11B5/82; G11B5/825; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24273; Y10T428/24322; Y10T428/25; Y10T428/254; Y10T428/259; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
99 words
A flexible magnetic disc sheet having a central circular hole therein and having a protective layer only on a surface portion surrounding the edge of the central circular hole, said protective layer being prepared by coating (a) a compound having an acrylate bond or a methacrylate bond at the end of at least one of a main chain and a side chain of molecules thereof, and (b) a solid lubricating agent, and exposing the coated layer to radiation for polymerizing and hardening, wherein the thickness of the coated layer after polymerization and hardening is from 1 to 50 μm.
Claim 2
Dependent Claim
99 words
A flexible magnetic disc sheet having a central circular hole therein and having a protective layer only on a surface portion surrounding the edge of the central circular hole, said protective layer being prepared by coating (a) a compound having an acrylate bond or a methacrylate bond at the end of at least one of a main chain and a side chain of molecules thereof, and (b) a solid lubricating agent, and exposing the coated layer to radiation for polymerizing and hardening, wherein the thickness of the coated layer after polymerization and hardening is from 1 to 50 μm.
Claim 3
Dependent Claim
28 words
A flexible magnetic disc sheet as in claim 1, wherein the compound (a) has from 1 to 10 acrylate or methacrylate bonds per 1000 units of molecular weight.
Claim 4
Dependent Claim
28 words
A flexible magnetic disc sheet as in claim 2, wherein the compound (a) has from 1 to 6 acrylate or methacrylate bonds per 1000 units of molecular weight.
Claim 5
Dependent Claim
28 words
A flexible magnetic disc sheet as in claim 3, wherein the compound (a) has from 2 to 4 acrylate or methacrylate bonds per 1000 units of molecular weight.
Claim 6
Dependent Claim
19 words
A flexible magnetic disc sheet as in claim 1, wherein the rays for polymerizing and hardening are ultraviolet rays.
Claim 7
Dependent Claim
38 words
A flexible magnetic disc sheet as in claim 1, wherein the solid lubricating agent (b) is selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, boron nitride, graphite fluoride, metal oxides, silicon nitride, plastic, and metal.
Claim 8
Dependent Claim
48 words
A flexible magnetic disc sheet as in claim 6, wherein the solid lubricating agent (b) is selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, boron nitride, graphite fluoride, lead monooxide, molybdenum trioxide, silicon dioxide, silicon nitride, polytetrafluoroethylene, polyamides, polyacetal, polyethylene, polyimides, lead, copper and zinc.
Claim 9
Dependent Claim
29 words
A flexible magnetic disc sheet as in claim 7, wherein the solid lubricating agent (b) is selected from the group consisting of molybdenum disulfide, tungsten disulfide, and graphite fluoride.
Claim 10
Dependent Claim
32 words
A flexible magnetic disc sheet as in claim 1, wherein the content of the compound (b) is from 1 to 50 parts by weight per 100 parts by weight of compound (a).
Claim 11
Dependent Claim
32 words
A flexible magnetic disk sheet as in claim 9, wherein the content of the compound (b) is from 5 to 10 parts by weight per 100 parts by weight of compound (a).
Claim 12
Dependent Claim
26 words
A flexible magnetic disc sheet as in claim 1, wherein the thickness of the coated layer after polymerization and hardening is from 5 to 30 μm.
Claim 13
Dependent Claim
26 words
A flexible magnetic disc sheet as in claim 11, wherein the thickness of the coated layer after polymerization and hardening is from 10 to 20 μm.
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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) | 1991-01-25 | 1991-07-27 | 1992-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-25 | 1995-07-27 | 1996-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-25 | 1999-07-27 | 2000-01-26 | $7700.00 | Window Closed / Lapsed |