US4812358A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Konica Minolta Inc
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Filing: 1987-08-21
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Granted: 1989-03-14
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Expires: 2007-08-21
Abstract
Abstract A magnetic recording medium is described which comprises a magnetic layer containing a magnetic powder, a first carbon black having a BET specific surface value of 80 m 2 /g to 900 m 2 /g and a DBP oil absorption value of less than 110 ml/100 g. The second carbon black is present in an amount of 3 to 15 parts by weight per 100 parts by weight of magnetic powder.
Inventors
- 👤 Toru Miyake
- 👤 Yasushi Nakano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:54
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; Y10T428/30
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
145 words
A magnetic recording medium comprising a magnetic layer, said magnetic layer comprising a magnetic powdery material, a first carbon black having a specific surface in terms of a BET value of from 80 m 2 /g to 900 m 2 /g and an oil absorption in terms of DBP value of not less than 110ml/200 g, said first carbon black being present in a quantity of 0.1 to 10 parts by weight per 100 parts by weight of said magnetic powdery material, and a second carbon black having a specific surface in terms of BET value of not less than 50 m 2 /g and an oil absorption in terms of DBP value of less than 110 ml/100 g, said second carbon black being present in a quantity of 3 to 15 parts by weight per 100 parts by weight of said magnetic powdery material.
Claim 2
Dependent Claim
145 words
A magnetic recording medium comprising a magnetic layer, said magnetic layer comprising a magnetic powdery material, a first carbon black having a specific surface in terms of a BET value of from 80 m 2 /g to 900 m 2 /g and an oil absorption in terms of DBP value of not less than 110ml/200 g, said first carbon black being present in a quantity of 0.1 to 10 parts by weight per 100 parts by weight of said magnetic powdery material, and a second carbon black having a specific surface in terms of BET value of not less than 50 m 2 /g and an oil absorption in terms of DBP value of less than 110 ml/100 g, said second carbon black being present in a quantity of 3 to 15 parts by weight per 100 parts by weight of said magnetic powdery material.
Claim 3
Dependent Claim
34 words
The magnetic recording medium of claim 1, wherein said specific surface of said first carbon black is in terms of a BET value of from 80 m 2 /g to 400 m 2 /g.
Claim 4
Dependent Claim
34 words
The magnetic recording medium of claim 2, wherein said specific surface of said first carbon black is in terms of a BET value of from 80 m 2 /g to 200 m 2 /g.
Claim 5
Dependent Claim
32 words
The magnetic recording medium of claim 1, wherein said oil absorption of said first carbon black is in terms of a DBP value of from 110 ml/100 g to 200 ml/100 g.
Claim 6
Dependent Claim
32 words
The magnetic recording medium of claim 4, wherein said oil absorption of said first carbon black is in terms of a DBP value of from 110 ml/100 g to 160 ml/100 g.
Claim 7
Dependent Claim
34 words
The magnetic recording medium of claim 1, wherein said specific surface of said second carbon black is in terms of a BET value of from 50 m 2 /g to 400 m 2 /g.
Claim 8
Dependent Claim
34 words
The magnetic recording medium of claim 6, wherein said specific surface of said second carbon black is in terms of a BET value of from 50 m 2 /g to 200 m 2 /g.
Claim 9
Dependent Claim
41 words
The magnetic recording medium of claim 1, wherein said first carbon black and said second carbon black are added in a total amount there of 3.1 to 20 parts by weight to 100 parts by weight of said magnetic powdery material.
Claim 10
Dependent Claim
38 words
The magnetic recording medium of claim 8, wherein said total amount of said first carbon black and said second carbon black is 3.1 to 15 parts by weight to 100 parts by weight of said magnetic powdery material.
Claim 11
Dependent Claim
34 words
The magnetic recording medium of claim 1, wherein said first carbon black is present in an amount of 0.1 to 5 parts by weight to 100 parts by weight of said magnetic powdery material.
Claim 12
Dependent Claim
34 words
The magnetic recording medium of claim 1, wherein said second carbon black is present in an amount of 5 to 12 parts by weight to 100 parts by weight of said magnetic powdery material.
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) | 1992-03-13 | 1992-09-12 | 1993-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-13 | 1996-09-12 | 1997-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-13 | 2000-09-12 | 2001-03-14 | $7700.00 | Window Closed / Lapsed |