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US4731278A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1986-05-13
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Granted: 1988-03-15
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Expires: 2006-05-13
Abstract
Abstract A magnetic recording medium is described, comprising a magnetic layer containing ferromagnetic fine particles and a binder coated on one side of a non-magnetic support and a backing layer coated on the opposite side of the non-magnetic support, wherein said ferromagnetic fine particles have a cobalt content of from 2 to 10 wt % with respect to the iron oxide content thereof, the content of divalent iron (Fe 2+ ) of from 1 to 10 wt % with respect to the trivalent iron (Fe 3+ ) content thereof, and the specific surface area of from 30 to 50 m 2 /g, said binder comprises a copolymer of vinyl chloride-vinyl acetate-maleic acid contained in an amount of 40 wt % or more with respect to the total binder content of the magnetic layer, an abrasive agent having a Mohs hardness of 6 or more is contained in said magnetic layer, and the resulting magnetic tape has a coercive force of from 750 to 900 Oe at 25° C.
Inventors
- 👤 Katsumi Ryoke
- 👤 Masatoshi Takahashi
- 👤 Eiichi Tadokoro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; G11B5/702; G11B5/7023; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
166 words
A magnetic digital recording medium comprising a magnetic layer containing ferromagnetic fine particles and a binder coated on one side of a non-magnetic support and a backing layer coated on the opposite side of the non-magnetic support, wherein said ferromagnetic fine particles have a cobalt content of from 2 to 10 wt % with respect to the iron oxide content thereof, the content of divalent iron (Fe 2+ ) of from 1 to 10 wt % with respect to the trivalent iron (Fe 3+ ) content thereof, and the specific surface area of from 30 to 50 m 2 /g, said binder comprises a copolymer of vinyl chloride-vinyl acetate-maleic acid contained in an amount of 40 wt % or more with respect to the total binder content of the magnetic layer, an abrasive agent having a Mohs hardness of 6 or more is contained in said magnetic layer, and the resulting magnetic tape has a coercive force of from 750 to 900 Oe at 25° C.
Claim 2
Dependent Claim
166 words
A magnetic digital recording medium comprising a magnetic layer containing ferromagnetic fine particles and a binder coated on one side of a non-magnetic support and a backing layer coated on the opposite side of the non-magnetic support, wherein said ferromagnetic fine particles have a cobalt content of from 2 to 10 wt % with respect to the iron oxide content thereof, the content of divalent iron (Fe 2+ ) of from 1 to 10 wt % with respect to the trivalent iron (Fe 3+ ) content thereof, and the specific surface area of from 30 to 50 m 2 /g, said binder comprises a copolymer of vinyl chloride-vinyl acetate-maleic acid contained in an amount of 40 wt % or more with respect to the total binder content of the magnetic layer, an abrasive agent having a Mohs hardness of 6 or more is contained in said magnetic layer, and the resulting magnetic tape has a coercive force of from 750 to 900 Oe at 25° C.
Claim 3
Dependent Claim
32 words
A magnetic digital recording medium as in claim 1, wherein the center line average roughness (Ra) of the backing layer is 0.014 μm or less at a cutoff value of 0.8 mm.
Claim 4
Dependent Claim
53 words
A magnetic digital recording medium as in claim 1, wherein the content of divalent iron (Fe 2+ ) is from 1 to 8 wt % with respect to the trivalent iron (Fe 3+ ) content, and the Co content is from 3 to 8 wt % with respect to the iron oxide content.
Claim 5
Dependent Claim
53 words
A magnetic digital recording medium as in claim 1, wherein the content of divalent iron (Fe 2+ ) is from 1 to 5 wt % with respect to the trivalent iron (Fe 3+ ) content, and the Co content is from 4 to 6 wt % with respect to the iron oxide content.
Claim 6
Dependent Claim
31 words
A magnetic digital recording medium as in claim 1, wherein the total binder content is from 5 to 300 parts by weight per 100 parts by weight of ferromagnetic fine particles.
Claim 7
Dependent Claim
47 words
A magnetic digital recording medium as in claim 1, wherein the abrasive agent has an average particle size of from 0.01 to 5 μm, and is used in an amount of from 0.01 to 20 parts by weight per 100 parts by weight of total binder content.
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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) | 1991-03-15 | 1991-09-14 | 1992-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-15 | 1995-09-14 | 1996-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-15 | 1999-09-14 | 2000-03-15 | $7700.00 | Window Closed / Lapsed |