Patent US4745017A successfully refreshed from Google Patents.
US4745017A
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US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1984-06-04
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Granted: 1988-05-17
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Expires: 2004-06-04
Abstract
Abstract A magnetic recording medium which comprises a non-magnetic support having on the surface side thereof a magnetic recording layer and on the opposite side thereof a backing layer is disclosed. The backing layer contains carbon black and a binder and has a thickness of 2 μm or less. The carbon black is composed of fine-grained carbon black having a mean grain size of 10 to 30 mμ and coarse-grained carbon black having a mean grain size of 100 to 150 mμ. In the backing layer the ratio of the content of carbon black to the binder ranges from 1:0.5 to 1:3.5 by weight.
Inventors
- 👤 Takahito Miyoshi
- 👤 Masahiro Utumi
- 👤 Kenichi Masuyama
- 👤 Toshimitu Okutu
- 👤 Masaaki Fujiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/735; G11B5/7356; G11B5/7358; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/25; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/30
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
149 words
A magnetic recording medium comprising a non-magnetic support base; a magnetic recording layer on the surface side thereof; and a backing layer on the opposite side of the support containing carbon black and a binder, the backing layer having a thickness of 2 μm or less, the carbon black being composed of fine-grained carbon black having a mean grain size of 10 to 30 mμ and coarse-grained carbon black having a mean grain size of 100 to 150 mμ, the backing layer having a ratio of the content of the carbon black to that of the binder ranging from 1:0.5 to 1:3.5 by weight, wherein the ratio of the fine-grained carbon black to the coarse-grained carbon black is in the range og 99.5:0.5 to 50:50, and wherein the backing layer has a center line average roughness Ra of 0.024 μm or less under a cut-off condition of 0.08 mm.
Claim 2
Dependent Claim
149 words
A magnetic recording medium comprising a non-magnetic support base; a magnetic recording layer on the surface side thereof; and a backing layer on the opposite side of the support containing carbon black and a binder, the backing layer having a thickness of 2 μm or less, the carbon black being composed of fine-grained carbon black having a mean grain size of 10 to 30 mμ and coarse-grained carbon black having a mean grain size of 100 to 150 mμ, the backing layer having a ratio of the content of the carbon black to that of the binder ranging from 1:0.5 to 1:3.5 by weight, wherein the ratio of the fine-grained carbon black to the coarse-grained carbon black is in the range og 99.5:0.5 to 50:50, and wherein the backing layer has a center line average roughness Ra of 0.024 μm or less under a cut-off condition of 0.08 mm.
Claim 3
Dependent Claim
30 words
A magnetic recording medium as claimed in claim 1, wherein the ratio of the fine-grained carbon black to the coarse-grained carbon black is in the range of 99:1 to 60:40.
Claim 4
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 1, wherein the binder in the backing layer has a glass transition temperature (Tg) of 40° C. or more.
Claim 5
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 3 wherein the binder in the backing layer has a glass transition temperature (Tg) of 60° C. or more.
Claim 6
Dependent Claim
31 words
A magnetic recording medium as claimed in claim 1, wherein the ratio of the content of the carbon black to that of the binder ranges from 1/0.8 to 1/3.0 by weight.
Claim 7
Dependent Claim
21 words
A magnetic recording medium as claimed in claim 1, wherein the thickness of the backing layer is 0.5 to 1.5 μm.
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) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |