US4671978A
Expired / Lapsed
US
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Flexible magnetic disc sheet
Assignee: Fujifilm Holdings Corp
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Filing: 1985-05-07
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Granted: 1987-06-09
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Expires: 2005-05-07
Abstract
Abstract A flexible magnetic disc sheet is described, which has a central circular hole therein and has a protective layer only on a surface portion surrounding the edge of the central circular hole, the protective layer comprising (a) a radiation polymerized polymer of a compound which is polymerizable and hardenable by radiation and (b) a matting agent.
Inventors
- 👤 Mikihiko Kato
- 👤 Shigeo Komine
- 👤 Katsumi Koyota
- 👤 Kouji Nakata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:50
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; G11B5/825; G11B23/00; G11B23/0014; G11B23/0021; G11B23/0028; G11B23/0035; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/251; Y10T428/252; Y10T428/254; Y10T428/256; Y10T428/257; Y10T428/27; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
83 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 comprising (a) a radiation polymerized polymer of a compound which is polymerizable and hardenable by exposure to radiation and (b) a matting agent, wherein the thickness of the protective layer is from 1 to 30 μm and wherein the matting agent has an average particle diameter of 1 to 10 μm.
Claim 2
Dependent Claim
83 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 comprising (a) a radiation polymerized polymer of a compound which is polymerizable and hardenable by exposure to radiation and (b) a matting agent, wherein the thickness of the protective layer is from 1 to 30 μm and wherein the matting agent has an average particle diameter of 1 to 10 μm.
Claim 3
Dependent Claim
35 words
A flexible magnetic disc sheet as in claim 1, wherein said protective layer being formed by exposing to radiation a layer containing a compound which is polymerizable and hardenable by radiation and a matting agent.
Claim 4
Dependent Claim
50 words
A flexible magnetic disc sheet as in claim 1, wherein said protective layer is formed by providing a coating layer comprising a compound which is polymerizable and hardenable by radiation on said surface portion, scattering said matting agent onto said coating layer and exposing to radiation the resultant composition layer.
Claim 5
Dependent Claim
66 words
A flexible magnetic disc sheet as in claim 1, wherein said compound which is polymerizable and hardenable by exposure to radiation is selected from the group consisting of a compound having one or more unsaturated carbon-to-carbon bonds, containing an acryloyl group, an acrylamido group or an allyl group, a compound having an ether bond with a vinyl compound or a thiovinyl compound, and an unsaturated polyester.
Claim 6
Dependent Claim
47 words
A flexible magnetic disc sheet as in claim 4, wherein said compound which is polymerizable and hardenable by exposure to radiation is selected from the group consisting of methyl acrylate, an ester of alkyl acrylate, styrene, α-methylstyrene, β-chlorostyrene, acrylonitrile, vinyl acetate, and vinyl propionate, and mixtures thereof.
Claim 7
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 5, wherein said compound which is polymerizable and hardenable by exposure to radiation is selected from the group consisting of methyl acrylate and methyl methacrylate.
Claim 8
Dependent Claim
34 words
A flexible magnetic disc sheet as in claim 4, wherein said compound which is polymerizable and hardenable by exposure to radiation is a compound having two or more of unsaturated bond in a molecule.
Claim 9
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 7, wherein said compound having two or more of unsaturated bond in the molecule is selected from the group consisting of unsaturated esters of polyol.
Claim 10
Dependent Claim
40 words
A flexible magnetic disc sheet as in claim 8, wherein said ester is selected from the group consisting of ethylene diacrylate, diethylene glycol diacrylate, glycerol triacrylate, ethylene diacrylate, pentaerythritol tetraacrylate and glycidyl acrylate having an epoxy ring, and mixtures thereof.
Claim 11
Dependent Claim
36 words
A flexible magnetic disc sheet as in claim 4, wherein said compound which is polymerizable and hardenable by exposure to radiation is a compound represented by formula ##STR2## wherein n is 0 or a positive integer.
Claim 12
Dependent Claim
38 words
A flexible magnetic disc sheet as in claim 10, wherein said compound has a skeleton selected from the group consisting of a polyurethane skeleton, an epoxy resin skeleton, a polyethylene skeleton, and a polycarbonate skeleton and mixtures thereof.
Claim 13
Dependent Claim
28 words
A flexible magnetic disc sheet as in claim 11, wherein said compound has a skeleton selected from the group consisting of a polyester skeleton and a polyurethane skeleton.
Claim 14
Dependent Claim
21 words
A flexible magnetic disc sheet as in claim 10, wherein said compound has a molecular weight of from 1,000 to 20,000.
Claim 15
Dependent Claim
26 words
A flexible magnetic disc sheet as in claim 1, wherein said radiation is selected from the group consisting of ultraviolet rays, α-rays, X-rays and electron beams.
Claim 16
Dependent Claim
15 words
A flexible magnetic disc sheet as in claim 14, wherein said radiation is ultraviolet rays.
Claim 17
Dependent Claim
78 words
A flexible magnetic disc sheet as in claim 1, wherein the matting agent comprises organic or inorganic fine particles selected from inorganic fine particles of zinc oxide, nickel oxide, titanium oxide, silicon oxide, barium sulfate, talc, kaolin, chromium oxide, cadmium sulfide, goethite, alumina, and calcium carbonate, and organic fine particles selected from acetyl cellulose, polyethylene, polypropylene, polystyrene,thermoplastic polyester, polyamide, polyacrylonitrile, polyacetal resin powder, phenol resin, urea resin, triazine resin, melamine resin, epoxy resin, furan resin, and acrolein resin.
Claim 18
Dependent Claim
28 words
A flexible magnetic disc sheet as in claim 16, wherein the matting agent is selected from the group consisting of silicon oxide, alumina, urea resin, and furan resin.
Claim 19
Dependent Claim
23 words
A flexible magnetic disk sheet as in claim 1, wherein the matting agent has an average particle diameter of 2 to 8 μm.
Claim 20
Dependent Claim
22 words
A flexible magnetic disc sheet as in claim 1, wherein the width of the protective layer is from 2 to 5 mm.
Claim 21
Dependent Claim
31 words
A flexible magnetic disc sheet as in claim 19, wherein the width of the protective layer is from 2.5 to 3.5 mm in the case of a 5.25 inch disk sheet.
Claim 22
Dependent Claim
31 words
A flexible magnetic disc sheet as in claim 20, wherein the width of the protective layer is from 2.75 to 3.25 mm in the case of a 5.25 inch disk sheet.
Claim 23
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 1, wherein the clearance between the edge of the protective layer and the edge of the central circular hole is from 15 to 500 μm.
Claim 24
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 22, wherein the clearance between the edge of the protective layer and the edge of the central circular hole is from 30 to 400 μm.
Claim 25
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 23, wherein the clearance between the edge of the protective layer and the edge of the central circular hole is from 50 to 300 μm.
Claim 26
Dependent Claim
45 words
A flexible magnetic disc sheet as in claim 2, wherein the content of the matting agent in the coating composition is from 1 to 50 parts by weight per 100 parts by weight of the compound which is polymerizable and hardenable by exposure to radiation.
Claim 27
Dependent Claim
45 words
A flexible magnetic disc sheet as in claim 25, wherein the content of the matting agent in the coating composition is from 5 to 30 parts by weight per 100 parts by weight of the compound which is polymerizable and hardenable by exposure to radiation.
Claim 28
Dependent Claim
45 words
A flexible magnetic disc sheet as in claim 26, wherein the content of the matting agent in the coating composition is from 10 to 30 parts by weight per 100 parts by weight of the compound which is polymerizable and hardenable by exposure to radiation.
Claim 29
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 3, wherein the matting agent is formed of organic or inorganic fine particles sprayed in an amount of from 1 to 500 mg/m 2 .
Claim 30
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 28, wherein the matting agent is formed of organic or inorganic fine particles sprayed in an amount of from 5 to 400 mg/m 2 .
Claim 31
Dependent Claim
33 words
A flexible magnetic disc sheet as in claim 29, wherein the matting agent is formed of organic or inorganic fine particles sprayed in an amount of from 10 to 200 mg/m 2 .
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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) | 1990-06-08 | 1990-12-08 | 1991-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-08 | 1994-12-08 | 1995-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-08 | 1998-12-08 | 1999-06-09 | $7700.00 | Window Closed / Lapsed |