US4654258A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1986-02-04
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Granted: 1987-03-31
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Expires: 2006-02-04
Abstract
Abstract A magnetic recording medium is described, comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles, a binder, non-magnetic particles, and lubricating agents, wherein said magnetic layer contains (i) carbon black (A) having an average particle size of 25 mμ or less and a BET specific surface area of from 150 to 250 m 2 /g and carbon black (B) having an average particle size of from 10 to 30 mμ and a BET specific surface area of 700 m 2 /g or more, and (ii) a fatty acid ester and a fatty acid amide in a total amount of 7 wt % or more based on the weight of the ferromagnetic particles.
Inventors
- 👤 Toshio Kawamata
- 👤 Yasuo Nishikawa
- 👤 Kazuhiko Morita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/71; G11B5/708; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
106 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles, a binder, non-magnetic particles, and lubricating agents, and wherein said magnetic layer contains additionally (i) carbon black (A) having an average from 150 to 250 m 2 /g and carbon black (B) having an average particle size of from 10 to 30 mμ and a BET specific surface area of 700 m 2 /g or more, and including as said lubricating agents (ii) a fatty acid ester and a fatty acid amide in a total amount of 7 wt% or more based on the weight of the ferromagnetic particles.
Claim 2
Dependent Claim
106 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles, a binder, non-magnetic particles, and lubricating agents, and wherein said magnetic layer contains additionally (i) carbon black (A) having an average from 150 to 250 m 2 /g and carbon black (B) having an average particle size of from 10 to 30 mμ and a BET specific surface area of 700 m 2 /g or more, and including as said lubricating agents (ii) a fatty acid ester and a fatty acid amide in a total amount of 7 wt% or more based on the weight of the ferromagnetic particles.
Claim 3
Dependent Claim
25 words
A magnetic recording medium as claimed in claim 1, wherein the non-magnetic particles in the magnetic layer have a Mohs' hardness of 6 or more.
Claim 4
Dependent Claim
36 words
A magnetic recording medium as in claim 1, wherein the total amount of the carbon black (A) and the carbon black (B) is from 1 to 25 wt% based on the weight of the ferromagnetic particles.
Claim 5
Dependent Claim
29 words
A magnetic recording medium as in claim 1, wherein the mixing ratio by weight of the carbon black (A) to the carbon black (B) is from 1/5 to 20/1.
Claim 6
Dependent Claim
29 words
A magnetic recording medium as in claim 2, wherein the particle size of the non-magnetic particles having a Mohs' hardness of 6 or more is 1 μm or less.
Claim 7
Dependent Claim
26 words
A magnetic recording medium as in claim 2, wherein the amount of the non-magnetic particles is 3 wt% based on the weight of the ferromagnetic particles.
Claim 8
Dependent Claim
44 words
A magnetic recording medium as in claim 1, wherein the fatty acid ester is selected from the group consisting of butyl stearate and butyl palmitate and the fatty acid amide is selected from the group consisting of oleyl amide, stearyl amide, and palmityl amide.
Claim 9
Dependent Claim
122 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles, a binder, non-magnetic particles, and lubricating agents, and wherein said magnetic layer contains additionally (i) carbon black (A) having an average particle size of from 16 to 20 mμ and a BET specific surface area of from 180 to 230 m 2 /g and carbon black (B) having an average particle size of from 20 to 30 mμ and a BET specific surface area of from 900 to 1,100 m 2 /g, and including as said lubricating agents (ii) a fatty acid ester and a fatty acid amide in a total amount of 7 wt% or more based on the weight of the ferromagnetic particles.
Claim 10
Dependent Claim
122 words
A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles, a binder, non-magnetic particles, and lubricating agents, and wherein said magnetic layer contains additionally (i) carbon black (A) having an average particle size of from 16 to 20 mμ and a BET specific surface area of from 180 to 230 m 2 /g and carbon black (B) having an average particle size of from 20 to 30 mμ and a BET specific surface area of from 900 to 1,100 m 2 /g, and including as said lubricating agents (ii) a fatty acid ester and a fatty acid amide in a total amount of 7 wt% or more based on the weight of the ferromagnetic particles.
Claim 11
Dependent Claim
25 words
A magnetic recording medium as claimed in claim 8, wherein the non-magnetic particles in the magnetic layer have a Mohs' hardness of 6 or more.
Claim 12
Dependent Claim
36 words
A magnetic recording medium as in claim 8, wherein the total amount of the carbon black (A) and the carbon black (B) is from 5 to 15 wt% based on the weight of the ferromagnetic particles.
Claim 13
Dependent Claim
29 words
A magnetic recording medium as in claim 8, wherein the mixing ratio by weight of the carbon black (A) to the carbon black (B) is from 1/3 to 10/1.
Claim 14
Dependent Claim
42 words
A magnetic recording medium as in claim 8, wherein the fatty acid ester is selected from the group consisting of butylstearate and butylpalmitate and the fatty acid amide is selected from the group consisting of oleyl amide, stearyl amide, and palmityl amide.
Claim 15
Dependent Claim
30 words
A magnetic recording medium as in claim 9, wherein the particle size of the non-magnetic particles having a Mohs' hardness of 6 or more is from 0.2 to 0.7 μm.
Claim 16
Dependent Claim
29 words
A magnetic recording medium as in claim 9, wherein the amount of the non-magnetic particles is from 6 to 15 wt% based on the weight of the ferromagnetic particles.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-30 | 1990-09-29 | 1991-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-30 | 1994-09-29 | 1995-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-30 | 1998-09-29 | 1999-03-31 | $7700.00 | Window Closed / Lapsed |