Patent US4647503A successfully refreshed from Google Patents.
US4647503A
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US
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Magnetic recording medium including magnetic layer with carbon black particles and a fatty acid ester
Assignee: Fujifilm Holdings Corp
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Filing: 1985-11-25
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Granted: 1987-03-03
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Expires: 2005-11-25
Abstract
Abstract A magnetic recording medium is disclosed. The medium is comprised of a non-magnetic support base having a surface with a center line average loughness (Ra) of not more then 0.035 μm, having coated thereon a magnetic layer. The magnetic layer is comprised of a ferromagnetic powder, a fatty acid ester and two types of carbon black dispersed in a binder. The first type of carbon black has an average primary particles sizes of 10 to 30 mμ. The second type of carbon black has an average primary particle size of 60 to 120 mμ. The first type of carbon black and second type of carbon black are present in a mixing weight ratio in the range of 60/40 to 95/5. The magnetic recording medium has excellent electromagnetic properties and provides a tape having good running property and durability.
Inventors
- 👤 Nobutaka Yamaguchi
- 👤 Masaaki Fujiyama
- 👤 Kazuo Kato
- 👤 Akira Kashiwagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:23
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/71; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
115 words
A magnetic recording medium comprising a non-magnetic support base having a surface which has a center line average roughness (Ra) of not more than 0.035 μm, and a magnetic layer coated on the surface of the support base, the magnetic layer comprising a binder and: (1) carbon black particles having an average primary particle size within the range of 10 to 30 mμ; (2) carbon black particles having an average primary particle size within the range of 60 to 120 mμ, wherein the mixing weight ratio of (1)/(2) is in the range of 70/30 to 90/10; (3) a fatty acid ester having a melting point of 70° C. or less; and (4) a ferromagnetic powder.
Claim 2
Dependent Claim
115 words
A magnetic recording medium comprising a non-magnetic support base having a surface which has a center line average roughness (Ra) of not more than 0.035 μm, and a magnetic layer coated on the surface of the support base, the magnetic layer comprising a binder and: (1) carbon black particles having an average primary particle size within the range of 10 to 30 mμ; (2) carbon black particles having an average primary particle size within the range of 60 to 120 mμ, wherein the mixing weight ratio of (1)/(2) is in the range of 70/30 to 90/10; (3) a fatty acid ester having a melting point of 70° C. or less; and (4) a ferromagnetic powder.
Claim 3
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black particles (1) have an average primary particle size in the range of 15 to 25 mμ.
Claim 4
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black particles (2) have an average primary particle size within the range of 70 to 100 mμ.
Claim 5
Dependent Claim
45 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black particles (1) and carbon black particles (2) are present in a total amount within the range of 1 to 20 parts by weight per 100 parts by weight of the ferromagnetic powder.
Claim 6
Dependent Claim
45 words
A magnetic recording medium as claimed in claim 4, wherein the carbon black particles (1) and carbon black particles (2) are present in a total amount within the range of 3 to 15 parts by weight per 100 parts by weight of the ferromagnetic powder.
Claim 7
Dependent Claim
35 words
A magnetic recording medium as claimed in claim 1, wherein the fatty acid ester is comprised of a fatty acid containing 6 to 32 carbon atoms and an alcohol containing 1 to 20 carbon atoms.
Claim 8
Dependent Claim
28 words
A magnetic recording medium as claimed in claim 6, wherein the fatty acid contains 8 to 22 carbon atoms and the alcohol contains 2 to 10 carbon atoms.
Claim 9
Dependent Claim
23 words
A magnetic recording medium as claimed in claim 1, wherein the fatty acid ester has a melting point of 50° C. or less.
Claim 10
Dependent Claim
38 words
A magnetic recording medium as claimed in claim 8, wherein the fatty acid ester is present in an amount within the range of 0.05 to 5 parts by weight per 100 parts by weight of the ferromagnetic powder.
Claim 11
Dependent Claim
38 words
A magnetic recording medium as claimed in claim 9, wherein the fatty acid ester is present in an amount within the range of 0.1 to 3 parts by weight per 100 parts by weight of the ferromagnetic powder.
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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) | 1990-03-02 | 1990-09-01 | 1991-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-02 | 1994-09-01 | 1995-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-02 | 1998-09-01 | 1999-03-03 | $7700.00 | Window Closed / Lapsed |