US4551386A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording materials
Assignee: Fujifilm Holdings Corp
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Filing: 1984-04-04
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Granted: 1985-11-05
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Expires: 2004-04-04
Abstract
Abstract A magnetic recording material comprised of a non-magnetic support base having provided thereon a magnetic recording layer on one side and the back layer on the other side is disclosed. The magnetic recording layer is comprised of ferromagnetic particles dispersed in a binder in combination with carbon black particles having an average primary particle size of 30 μm or less. The back layer is comprised of a binder having dispersed therein carbon black having an average primary particle size in the range of 50 to 150 mμ. The magnetic recording material has improved electromagnetic properties and improved durability, particularly with respect to video S/N and dropout.
Inventors
- 👤 Nobutaka Yamaguchi
- 👤 Shinobu Iida
- 👤 Masahiro Utsumi
- 👤 Toshimitu Okutu
- 👤 Kenichi Masuyama
- 👤 Eiichi Tadokoro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:35
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/735; G11B5/7356; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/30
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
121 words
A magnetic recording material, comprising: a non-magnetic support having provided on one side thereof; a magnetic recording layer comprised of ferromagnetic particles dispersed in a binder with carbon black particles having an average primary particle size of 30 mμ or less; and a back layer provided on the other side of the support, the back layer being comprised of a binder having dispersed therein carbon black having an average primary particle size in the range of 50 to 150 mμ, wherein the magnetic recording layer includes the carbon black having an average particle size of 30 mμ or less in an amount in the range of 1 to 20 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 2
Dependent Claim
121 words
A magnetic recording material, comprising: a non-magnetic support having provided on one side thereof; a magnetic recording layer comprised of ferromagnetic particles dispersed in a binder with carbon black particles having an average primary particle size of 30 mμ or less; and a back layer provided on the other side of the support, the back layer being comprised of a binder having dispersed therein carbon black having an average primary particle size in the range of 50 to 150 mμ, wherein the magnetic recording layer includes the carbon black having an average particle size of 30 mμ or less in an amount in the range of 1 to 20 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 3
Dependent Claim
32 words
A magnetic recording material as claimed in claim 1, wherein the carbon black in the magnetic recording layer has an average primary particle size in the range of 5 to 25 mμ.
Claim 4
Dependent Claim
31 words
A magnetic recording material as claimed in claim 2, wherein the magnetic recording layer includes carbon black having an average primary particle size in the range of 10 to 20 mμ.
Claim 5
Dependent Claim
32 words
A magnetic recording material as claimed in claim 2, where in the carbon black in the back layer has an average primary particle size in the range of 70 to 120 mμ.
Claim 6
Dependent Claim
31 words
A magnetic recording material as claimed in claim 3, wherein the carbon black in the back layer has an average primary particle size in the range of 80 to 110 mμ.
Claim 7
Dependent Claim
42 words
A magnetic recording material as claimed in claim 1, wherein the carbon black in the magnetic recording layer is present in an amount in the range of 3 to 15 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 8
Dependent Claim
54 words
A magnetic recording material as claimed in claim 1, wherein the back layer includes a carbon black having a particle size in the range of 50 to 150 mμ in an amount in the range of 5 to 500 parts by weight per 100 parts by weight of the binder in the back layer.
Claim 9
Dependent Claim
55 words
A magnetic recording material as claimed in claim 6, wherein the back layer includes carbon black having an average primary particle size in the range of 50 to 150 mμ in an amount in the range of 10 to 200 parts by weight per 100 parts by weight of the binder in the back layer.
Claim 10
Dependent Claim
21 words
A magnetic recording material as claimed in claim 1, wherein the back layer has a thickness of 0.01 to 3 μm.
Claim 11
Dependent Claim
21 words
A magnetic recording material as claimed in claim 9, wherein the back layer has a thickness of 0.1 to 2 μm.
Claim 12
Dependent Claim
24 words
A magnetic recording material as claimed in claim 10, wherein the back layer has a thickness in the range of 0.3 to 1.5 μm.
Claim 13
Dependent Claim
26 words
A magnetic recording material as claimed in claim 1, wherein the ferromagnetic particles have the BET specific surface area of 20 m 2 /g or more.
Claim 14
Dependent Claim
26 words
A magnetic recording material as claimed in claim 12, wherein the ferromagnetic particles have the BET specific surface area of 20 to 70 m 2 /g.
Claim 15
Dependent Claim
26 words
A magnetic recording material as claimed in claim 13, wherein the ferromagnetic particles have the BET specific surface area of 30 to 70 m 2 /g.
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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) | 1988-11-04 | 1989-05-06 | 1989-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-04 | 1993-05-06 | 1993-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-04 | 1997-05-06 | 1997-11-05 | $7700.00 | Window Closed / Lapsed |