US4546038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1983-04-29
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Granted: 1985-10-08
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Expires: 2003-04-29
Abstract
Abstract A magnetic recording medium is disclosed which is comprised of a non-magnetic support having a magnetic layer provided thereon. The magnetic layer is comprised of two different types of carbon black having different particle sizes, a lubricant which is liquid at room temperature, a ferromagnetic powder all dispersed in a binder. A carbon black (1) has an average particle size smaller than 50 mμ and a carbon black (2) has an average particle size of larger than 120 mμ. The carbon black is present in a weight ratio of (1)/(2) within the range of 50/50 to 97/3. The magnetic recording medium has improved electromagnetic properties and running durability. In addition, the material provides an improved S/N ratio and an improved coefficient of friction.
Inventors
- 👤 Nobutaka Yamaguchi
- 👤 Masaaki Fujiyama
- 👤 Katsumi Ryoke
- 👤 Eiichi Tadokoro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:32
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
96 words
A magnetic recording medium, having improved running durability, an improved S/N ratio and an improved coefficient of friction comprising: a non-magnetic support having provided thereon; a magnetic layer, wherein the magnetic layer is comprised of: (1) a carbon black having an average primary particle size of smaller than 50 mμ; (2) a carbon black having an average primary particle size of larger than 150 mμ wherein the weight ratio of (1)/(2) is within the range of 60/40 to 90/10; (3) a lubricant which is in a liquid state at normal temperature; ferromagnetic particles; and a binder.
Claim 2
Dependent Claim
96 words
A magnetic recording medium, having improved running durability, an improved S/N ratio and an improved coefficient of friction comprising: a non-magnetic support having provided thereon; a magnetic layer, wherein the magnetic layer is comprised of: (1) a carbon black having an average primary particle size of smaller than 50 mμ; (2) a carbon black having an average primary particle size of larger than 150 mμ wherein the weight ratio of (1)/(2) is within the range of 60/40 to 90/10; (3) a lubricant which is in a liquid state at normal temperature; ferromagnetic particles; and a binder.
Claim 3
Dependent Claim
28 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black (2) has an average primary particle size within the range of 200 to 1,000 mμ.
Claim 4
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 1, wherein the ferromagnetic particles have a surface area measured by BET method of not smaller than 30 m 2 /g.
Claim 5
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 3, wherein the ferromagnetic particles have a surface area measured by BET method of not smaller than 35 m 2 /g.
Claim 6
Dependent Claim
28 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black (1) has an average primary particle size within the range of 5 to 35 mμ.
Claim 7
Dependent Claim
18 words
A magnetic recording medium as claimed in claim 5, wherein the carbon black (1) has an average primary
Claim 8
Dependent Claim
38 words
A magnetic recording medium as claimed in claim 1, wherein the carbon blacks (1) and (2) are present in a total amount of 1 to 20 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 9
Dependent Claim
38 words
A magnetic recording medium as claimed in claim 7, wherein the carbon blacks (1) and (2) are present in a total amount of 3 to 15 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 10
Dependent Claim
34 words
A magnetic recording medium as claimed in claim 1, wherein the lubricant is present in an amount of 10 to 1000 parts by weight per 100 parts by weight of the carbon black (2).
Claim 11
Dependent Claim
37 words
A magnetic recording medium as claimed in claim 9, wherein the lubricant is present in an amount within the range of 20 to 750 parts by weight per 100 parts by weight of the carbon black (2).
Claim 12
Dependent Claim
37 words
A magnetic recording medium as claimed in claim 10, wherein the lubricant is present in an amount within the range of 50 to 500 parts by weight per 100 parts by weight of the carbon black (2).
Claim 13
Dependent Claim
113 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black (1) has an average primary particle size within the range of 5 to 30 mμ, the carbon black (2) has an average primary particle size within the range of 200 to 1000 mμ, the weight ratio of carbon blacks (1)/(2) is within the range of 60/40 to 90/10, carbon blacks (1) and (2) are present in a total amount of 1 to 20 parts by weight per 100 parts by weight of the ferromagnetic particles, and wherein the lubricant is present in an amount of 10 to 1000 parts by weight per 100 parts by weight of carbon black (2).
Claim 14
Dependent Claim
31 words
A magnetic recording medium as claimed in claim 12, wherein said lubricant is selected from the group consisting of silicon oils, liquid paraffins, fatty acids, fatty acid esters and fluorine-containing oils.
Claim 15
Dependent Claim
32 words
A magnetic recording medium as claimed in claim 13, wherein said binder is selected from the group consisting of cellulose derivatives, vinyl chloride-vinyl acetate resins, polyurethanes, epoxy resins, polyamides, polyisocyanates or polyesters.
Claim 16
Dependent Claim
113 words
A magnetic recording medium as claimed in claim 1, wherein the carbon black (1) has an average primary particle size within the range of 10 to 30 mμ, the carbon black (2) has an average primary particle size within the range of 200 to 1000 mμ, the weight ratio of carbon blacks (1)/(2) is within the range of 60/40 to 90/10, carbon blacks (1) and (2) are present in a total amount of 3 to 15 parts by weight per 100 parts by weight of the ferromagnetic particles, and wherein the lubricant is present in an amount of 20 to 750 parts by weight per 100 parts by weight of carbon black (2).
Claim 17
Dependent Claim
31 words
A magnetic recording medium as claimed in claim 15, wherein said lubricant is selected from the group consisting of silicon oils, liquid paraffins, fatty acids, fatty acid esters and fluorine-containing oils.
Claim 18
Dependent Claim
32 words
A magnetic recording medium as claimed in claim 16, wherein said binder is selected from the group consisting of cellulose derivatives, vinyl chloride-vinyl acetate resins, polyurethanes, epoxy resins, polyamides, polyisocyanates or polyesters.
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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) | 1988-10-07 | 1989-04-08 | 1989-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-07 | 1993-04-08 | 1993-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-07 | 1997-04-08 | 1997-10-08 | $7700.00 | Window Closed / Lapsed |