Patent US4407901A successfully refreshed from Google Patents.
US4407901A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1981-09-10
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Granted: 1983-10-04
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Expires: 2001-09-10
Abstract
Abstract A magnetic recording medium is disclosed comprising a non-magnetic base bearing a magnetic layer mainly consisting of ferromagnetic particles and a binder wherein the magnetic layer contains a polymer having a polar functional group and a degree of polymerization of not more than 100.
Inventors
- 👤 Hajime Miyatsuka
- 👤 Akira Kasuga
- 👤 Yasuyuki Yamada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2998
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
53 words
A magnetic recording medium, comprising: a non-magnetic base; and a magnetic layer on said base consisting mainly of ferromagnetic metal particles and a binder, said ferromagnetic particles are surface-treated with a polymer having a polar functional group and a degree of polymerization of not more than 100 and then dispersed in said binder.
Claim 2
Dependent Claim
53 words
A magnetic recording medium, comprising: a non-magnetic base; and a magnetic layer on said base consisting mainly of ferromagnetic metal particles and a binder, said ferromagnetic particles are surface-treated with a polymer having a polar functional group and a degree of polymerization of not more than 100 and then dispersed in said binder.
Claim 3
Dependent Claim
22 words
A magnetic recording medium as claimed in claim 1 wherein said polymer has a degree of polymerization of not more than 70.
Claim 4
Dependent Claim
22 words
A magnetic recording medium as claimed in claim 2, wherein said polymer has a degree of polymerization of not more than 50.
Claim 5
Dependent Claim
42 words
A magnetic recording medium as claimed in claim 1 wherein said polar functional group is selected from the groups consisting of carboxyl, hydroxyl, phenolic-hydroxyl, and sufonic and further wherein said groups are contained in an amount of 1 to 30 mol %.
Claim 6
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 4, wherein said polymer is contained in an amount of 0.1 to 10 wt % of the ferromagnetic particles.
Claim 7
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 5, wherein said polymer is contained in an amount of 0.3 to 7 wt % of the ferromagnetic particles.
Claim 8
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 6, wherein said polymer is contained in an amount of 0.5 to 5 wt % of the ferromagnetic particles.
Claim 9
Dependent Claim
108 words
A magnetic recording medium as claimed in claim 1 or 4, wherein said polymer is selected from the group consisting of (a) a copolymer with a backbone of acrylic acid ester or methacrylic acid ester and acrylic acid, methacrylic acid, crotonic acid or 2-hydroxymethyl acrylate as a functional moiety thereon, (b) a copolymer of vinyl chloride or vinyl acetate and maleic anhydride or vinyl alcohol, (c) a copolymer of styrene and a polymerizable unsaturated monomer having polar functional groups, (d) polyvinyl phenol, (e) polyvinyl alcohol, (f) polyvinyl acetal, (g) polystyrene sulfonic acid and (h) a copolymer of vinylidene chloride and a polymerizable unsaturated monomer having polar functional groups.
Claim 10
Dependent Claim
32 words
A magnetic recording medium as claimed in claim 8, wherein said polymer is selected from the group consisting of a butyl acrylate-acrylic acid copolymer, polyvinyl phenol and a lauryl methacrylate-acrylic acid copolymer.
Claim 11
Dependent Claim
26 words
A magnetic recording medium as in claim 8, wherein said polymer is selected from the group consisting of a butyl acrylate-acrylic acid copolymer and polyvinyl phenol.
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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) | 1986-10-03 | 1987-04-04 | 1987-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-03 | 1991-04-04 | 1991-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-03 | 1995-04-04 | 1995-10-04 | $7700.00 | Window Closed / Lapsed |