Patent US4598014A successfully refreshed from Google Patents.
US4598014A
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1984-11-16
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Granted: 1986-07-01
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Expires: 2004-11-16
Abstract
Abstract A magnetic recording medium is disclosed. The medium comprises a non-magnetic support having provided on opposite surfaces a magnetic recording layer and a backing layer containing two types of carbon black and a binder and having a thickness of 2 μm or less, one of said carbon black being fine carbon black having an average particle size of 30 to 100 mμ and the other of said carbon black being coarse carbon black having an average particle size of 150 to 500 mμ, and the mixing weight ratio of said carbon black and the binder being 1:1.5 to 1:3.5.
Inventors
- 👤 Takahito Miyoshi
- 👤 Kenichi Masuyama
- 👤 Toshimitu Okutu
- 👤 Masahiro Utumi
- 👤 Masaaki Fujiyama
- 👤 Minoru Kanazawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:48
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/735; G11B5/7356; G11B5/7358; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/258; Y10T428/30
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
95 words
A magnetic recording medium comprising a non-magnetic support having provided on opposite surfaces a magnetic recording layer and a backing layer containing two types of carbon black and a binder and having a thickness of 2 μm or less, one of said carbon black being fine carbon black having an average particle size of 30 to 100 mμ and the other of said carbon black being coarse carbon black having an average particle size of 150 to 500 mμ, and the mixing weight ratio of said carbon black and the binder being 1:0.5 to 1:3.5.
Claim 2
Dependent Claim
95 words
A magnetic recording medium comprising a non-magnetic support having provided on opposite surfaces a magnetic recording layer and a backing layer containing two types of carbon black and a binder and having a thickness of 2 μm or less, one of said carbon black being fine carbon black having an average particle size of 30 to 100 mμ and the other of said carbon black being coarse carbon black having an average particle size of 150 to 500 mμ, and the mixing weight ratio of said carbon black and the binder being 1:0.5 to 1:3.5.
Claim 3
Dependent Claim
33 words
The magnetic recording medium as claimed in claim 1, wherein said backing layer has a center line average roughness Ra of 0.01 to 0.03 μm at a cut off value of 0.08 mm.
Claim 4
Dependent Claim
27 words
The magnetic recording medium as claimed in claim 1, wherein said fine carbon black and said coarse carbon black have a mixing ratio of 99.5:0.5 to 50:50.
Claim 5
Dependent Claim
27 words
The magnetic recording medium as claimed in claim 3, wherein said fine carbon black and said coarse carbon black have a mixing ratio of 99:1 to 60:40.
Claim 6
Dependent Claim
32 words
The magnetic recording medium as claimed in claim 1, wherein said binder is selected from the group consisting of a thermoplastic resin, a thermosetting resin, a reactive type resin and mixtures thereof.
Claim 7
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1, wherein said binder has a glass transition temperature of 40° C. or more.
Claim 8
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 6, wherein said binder has a glass transition temperature of 60° C. or more.
Claim 9
Dependent Claim
23 words
The magnetic recording medium as claimed in claim 1, wherein said mixing weight ratio of carbon black and binder is 1:0.8 to 1:3.0.
Claim 10
Dependent Claim
33 words
The magnetic recording medium as claimed in claim 1, wherein said backing layer further comprises as a lubricating agent, a fatty acid or a fatty acid ester having 12 or more carbon atoms.
Claim 11
Dependent Claim
40 words
The magnetic recording medium as claimed in claim 1, wherein said magnetic recording layer contains Co-containing magnetic iron oxide having an S BET of 33 m 2 /g or more, ferromagnetic metal particles or hexagonal crystal type ferrite magnetic particles.
Claim 12
Dependent Claim
20 words
The magnetic recording medium as claimed in claim 1, wherein said magnetic recording layer is a thin ferromagnetic metal film.
Claim 13
Dependent Claim
25 words
The magnetic recording medium as claimed in claim 1, wherein said backing layer has a thickness in the range of from 0.3 to 2.0 μm.
Claim 14
Dependent Claim
25 words
The magnetic recording medium as claimed in claim 3, wherein said backing layer has a thickness in the range of from 0.3 to 2.0 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) | 1989-06-30 | 1989-12-30 | 1990-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-30 | 1993-12-30 | 1994-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-30 | 1997-12-30 | 1998-07-01 | $7700.00 | Window Closed / Lapsed |