US4683167A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic iron oxide pigment and recording media
Assignee: QUANTEGY MEDIA Corp
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Filing: 1984-06-25
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Granted: 1987-07-28
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Expires: 2004-06-25
Abstract
Abstract An improved magnetic particulate pigment suitable for use in recording media and media employing it are disclosed. The particles of the pigment comprise a magnetic core with an epitaxial layer containing approximately 0.05-2.0% of the total pigment as zinc ion. A process for preparing such particles is also disclosed.
Inventors
- 👤 Lawrence M. Scott
- 👤 Gary D. Rexroat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:12
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70657; G11B5/712; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
60 words
A magnetic recording medium having superior saturation magnetization properties comprising: a magnetic particulate pigment, with superior saturation magnetization, comprising a magnetic core and an epitaxial coating, wherein said coating comprises an inner layer of cobalt(II) hydroxide enveloped by an outer layer of iron(II) hydroxide, at least one of said layers impregnated with a saturation magnetization enhancing amount of zinc ion.
Claim 2
Dependent Claim
60 words
A magnetic recording medium having superior saturation magnetization properties comprising: a magnetic particulate pigment, with superior saturation magnetization, comprising a magnetic core and an epitaxial coating, wherein said coating comprises an inner layer of cobalt(II) hydroxide enveloped by an outer layer of iron(II) hydroxide, at least one of said layers impregnated with a saturation magnetization enhancing amount of zinc ion.
Claim 3
Dependent Claim
21 words
The medium of claim 1 wherein the saturation enhancing amount of zinc ion is between about 0.05 At% and 2 At%.
Claim 4
Dependent Claim
21 words
The medium of claim 2 wherein the saturation enhancing amount of zinc ion is between about 0.25 At% and 1 At%.
Claim 5
Dependent Claim
17 words
The medium of claim 3 wherein the saturation enhancing amount of zinc ion is about 0.5 At%.
Claim 6
Dependent Claim
16 words
The medium of claim 1 wherein the core is an acicular γ-Fe 2 O 3 .
Claim 7
Dependent Claim
24 words
The medium of claim 1 wherein the epitaxial cobalt and iron ion is each between about 2 At% and 10 At% of the pigment.
Claim 8
Dependent Claim
50 words
A magnetic particulate pigment with superior saturation magnetization comprising: a magnetic core, and an epitaxial coating, wherein said coating comprises an inner layer of cobalt(II) hydroxide enveloped by an outer layer of iron(II) hydroxide, at least one of said layers impregnated with a saturation magnetization enhancing amount of zinc ion.
Claim 9
Dependent Claim
50 words
A magnetic particulate pigment with superior saturation magnetization comprising: a magnetic core, and an epitaxial coating, wherein said coating comprises an inner layer of cobalt(II) hydroxide enveloped by an outer layer of iron(II) hydroxide, at least one of said layers impregnated with a saturation magnetization enhancing amount of zinc ion.
Claim 10
Dependent Claim
18 words
A process for preparing a magnetic medium which comprises coating a support with the pigment of claim 7.
Claim 11
Dependent Claim
64 words
A process for enhancing the saturation magnetization of a magnetic particulate pigment which process comprises (a) suspending magnetic particles in aqueous medium: (b) precipitating cobalt(II) hydroxide onto the particles, followed by (c) precipitating iron(II) hydroxide onto the particles, wherein the improvement comprises conducting at least one of step (b) or step (c) in the presence of a saturation magnetization enhancing amount of zinc ion.
Claim 12
Dependent Claim
64 words
A process for enhancing the saturation magnetization of a magnetic particulate pigment which process comprises (a) suspending magnetic particles in aqueous medium: (b) precipitating cobalt(II) hydroxide onto the particles, followed by (c) precipitating iron(II) hydroxide onto the particles, wherein the improvement comprises conducting at least one of step (b) or step (c) in the presence of a saturation magnetization enhancing amount of zinc ion.
Claim 13
Dependent Claim
18 words
The process of claim 9 wherein the step conducted in the presence of zinc ion is step (c).
Claim 14
Dependent Claim
16 words
The process of claim 9 wherein the magnetic particles are acicular γ-Fe 2 O 3 .
Claim 15
Dependent Claim
21 words
The process of claim 9 which further includes curing the particles with heat, recovering the particles from the slurry and drying.
Claim 16
Dependent Claim
24 words
The process of claim 9 wherein the saturation magnetization enhancing amount of zinc ion is between about 0.05% and 2.0 At% of the pigment.
Claim 17
Dependent Claim
23 words
The process of claim 9 wherein the saturation enhancing amount of zinc ion is between about 0.25% and 1 At% of the pigment.
Claim 18
Dependent Claim
20 words
The process of claim 9 wherein the saturation enhancing amount of zinc ion is approximately 0.5 At% of the pigment.
Claim 19
Dependent Claim
26 words
The process of claim 9 wherein the cobalt(II) and iron(II) are each provided in an amount between about 2 At% and 10 At% of the pigment.
Claim 20
Dependent Claim
10 words
A magnetic pigment prepared by the process of claim 9.
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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) | 1990-07-27 | 1991-01-26 | 1991-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-27 | 1995-01-26 | 1995-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-27 | 1999-01-26 | 1999-07-28 | $7700.00 | Window Closed / Lapsed |