US4002804A
Expired / Lapsed
US
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Magnetic recording material
Assignee: Fujifilm Holdings Corp
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Filing: 1975-07-31
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Granted: 1977-01-11
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Expires: 1995-07-31
Abstract
Abstract A magnetic recording material which comprises a support having thereon a magnetic recording layer comprising a ferromagnetic substance and a binder, wherein the ferromagnetic substance comprises a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5 mu or larger and a degree of oxidation represented by the value of x in FeOx of 1.33<x</=1.45 and (2) a Berthollide iron oxide having a particle size of about 0.4 mu or smaller and a degree of oxidation represented by the value of x in FeOx of 1.43</= x< 1.50, in which the weight ratio of Berthollide iron oxide (1) to Berthollide iron oxide (2) ranges from about 1:4 to 4:1.
Inventors
- 👤 Goro Akashi
- 👤 Masaaki Fujiyama
- 👤 Nobutaka Yamaguchi
- 👤 Satoru Takayama
- 👤 Koji Sasazawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:28
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/70684; G11B5/70694; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
122 words
A magnetic recording material which comprises a support having thereon a magnetic recording layer consisting essentially of a ferromagnetic material and a binder, wherein the ferromagnetic material is a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5 μ or larger and a degree of oxidation represented by the value of x in FeO x of 1.33 < x ≦ 1.45 and (2) a Berthollide iron oxide having a particle size of about 0.4 μ or smaller and a degree of oxidation represented by the value of x in FeO x of 1.43 ≦ x < 1.50, where the weight ratio of Berthollide iron oxide (1) to Berthollide iron oxide (2) ranges from about 1:4 to 4:1.
Claim 2
Dependent Claim
122 words
A magnetic recording material which comprises a support having thereon a magnetic recording layer consisting essentially of a ferromagnetic material and a binder, wherein the ferromagnetic material is a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5 μ or larger and a degree of oxidation represented by the value of x in FeO x of 1.33 < x ≦ 1.45 and (2) a Berthollide iron oxide having a particle size of about 0.4 μ or smaller and a degree of oxidation represented by the value of x in FeO x of 1.43 ≦ x < 1.50, where the weight ratio of Berthollide iron oxide (1) to Berthollide iron oxide (2) ranges from about 1:4 to 4:1.
Claim 3
Dependent Claim
44 words
The magnetic recording material as described in claim 1, wherein said iron oxide contains a divalent metal element other than iron to adjust the coercive force of the iron oxide and the content of said metal element is about 0.5 to 15 atom %.
Claim 4
Dependent Claim
34 words
The magnetic recording material of claim 2, wherein said metal element is at least one of cobalt, magnesium, copper, chromium, manganese, nickel, zinc, molybdenum, tin, antimony, tellurium, rhodium, barium, lanthanum, cerium, tungsten or bismuth.
Claim 5
Dependent Claim
30 words
The magnetic recording material of claim 1, wherein the difference in coercive force of said Berthollide iron oxide (1) and said Berthollide iron oxide (2) is less than about 15%.
Claim 6
Dependent Claim
19 words
The magnetic recording material of claim 1, wherein the envelope wave form fluctuation factor is about 12% or less.
Claim 7
Dependent Claim
32 words
The magnetic recording material of claim 1, wherein the magnetic recording layer further contains about 0.5 to 20 parts by weight of dispersing agent based on 100 parts by weight of binder.
Claim 8
Dependent Claim
31 words
The magnetic recording material of claim 1, wherein the magnetic recording layer further contains about 0.2 to 20 parts by weight of lubricant based on 100 parts by weight of binder.
Claim 9
Dependent Claim
44 words
The magnetic recording material of claim 1, wherein the magnetic recording layer further contains about 0.5 to 20 parts by weight of abrasives based on 100 parts by weight of binder, and said abrasives have a particle size of about 0.05 to 2 microns.
Claim 10
Dependent Claim
33 words
The magnetic recording material of claim 1, wherein the magnetic recording layer further contains about 0.5 to 1% by weight of an organic anti-static agent based on the weight of the ferromagnetic material.
Claim 11
Dependent Claim
30 words
The magnetic recording material of claim 1, wherein the magnetic recording layer further contains about 5% by weight of inorganic anti-static agent based on the weight of the ferromagnetic material.
Claim 12
Dependent Claim
21 words
The magnetic recording material of claim 1, wherein the thickness of the magnetic recording layer is about 0.5 to 20 microns.
Claim 13
Dependent Claim
24 words
The magnetic recording material of claim 1, wherein the support is non-magnetic and the thickness of the support is about 10 to 125 microns.
Claim 14
Dependent Claim
116 words
In a magnetic recording material which comprises a support having thereon a magnetic recording layer, the improvement which comprises a ferromagnetic material which is a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5μ or larger and a degree of oxidation represented by the value of x in FeO x of 1.33 < x ≦ 1.45 and (2) a Berthollide iron oxide having a particle size of about 0.4μ or smaller and a degree of oxidation represented by the value of x in FeO x of 1.43 ≦ x < 1.50, where the weight ratio of Berthollide iron oxide (1) to Berthollide iron oxide (2) ranges from about 1:4 to 4:1.
Claim 15
Dependent Claim
116 words
In a magnetic recording material which comprises a support having thereon a magnetic recording layer, the improvement which comprises a ferromagnetic material which is a mixture of (1) a Berthollide iron oxide having a particle size of about 0.5μ or larger and a degree of oxidation represented by the value of x in FeO x of 1.33 < x ≦ 1.45 and (2) a Berthollide iron oxide having a particle size of about 0.4μ or smaller and a degree of oxidation represented by the value of x in FeO x of 1.43 ≦ x < 1.50, where the weight ratio of Berthollide iron oxide (1) to Berthollide iron oxide (2) ranges from about 1:4 to 4:1.
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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) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |