Patent US4015042A successfully refreshed from Google Patents.
US4015042A
Expired / Lapsed
US
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Materials for magnetic recording having high resistance to wear and reduced abrasion on magnetic heads
Assignee: Eastman Kodak Co
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Filing: 1974-12-23
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Granted: 1977-03-29
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Expires: 1994-12-23
Abstract
Abstract Magnetic recording elements comprising a magnetic layer containing dispersed particles which improve the wear resistance of the layer are disclosed. Such elements comprise a non-magnetic support and a magnetic recording layer that contains dispersed in a binder, ferromagnetic particles for recording and non-ferromagnetic particles of different average particle size. These non-ferromagnetic particles of different particle size have a Mohs Hardness above that of the ferromagnetic particles. These non-ferromagnetic particles consist essentially of (a) particles having an average particle size similar to or larger than that of the ferromagnetic particles, of about 0.3 to about 2 microns, present at a concentration of about 0.005 to about 0.025 parts, by weight, based on the weight of the ferromagnetic particles, and (b) smaller particles having an average particle size up to about 0.1 micron, present at a concentration of about 0.02 to about 0.06 parts, by weight, based on the weight of the ferromagnetic particles. Suitable ferromagnetic particles include acicular iron oxides, chromium dioxide and the like. The magnetic recording elements disclosed herein, particularly the magnetic tapes, exhibit high resistance to wear and tear and low abrasiveness.
Inventors
- 👤 Yves Gilbert Chassaigne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:40
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/252; Y10T428/256; Y10T428/257; Y10T428/259; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
155 words
In an element comprising a non-magnetic support and a magnetic recording layer having dispersed in a binder, (1) ferromagnetic particles and (2) non-ferromagnetic particles that improve the wear resistance of said layer and have a Mohs Hardness above that of said ferromagnetic particles, the improvement wherein said non-ferromagnetic particles consist essentially of a bimodal distribution of (a) particles and (b) particles, said (a) particles having an average particle size similar to or larger than that of the ferromagnetic particles in the range of about 0.3 to about 2 microns and being present in a concentration in the range of about 0.005 to about 0.025 parts, by weight, based on the weight of said ferromagnetic particles and said (b) particles having an average particle size up to about 0.1 micron and being present in a concentration in the range of about 0.02 to about 0.06 parts, by weight, based on the weight of said ferromagnetic particles.
Claim 2
Dependent Claim
155 words
In an element comprising a non-magnetic support and a magnetic recording layer having dispersed in a binder, (1) ferromagnetic particles and (2) non-ferromagnetic particles that improve the wear resistance of said layer and have a Mohs Hardness above that of said ferromagnetic particles, the improvement wherein said non-ferromagnetic particles consist essentially of a bimodal distribution of (a) particles and (b) particles, said (a) particles having an average particle size similar to or larger than that of the ferromagnetic particles in the range of about 0.3 to about 2 microns and being present in a concentration in the range of about 0.005 to about 0.025 parts, by weight, based on the weight of said ferromagnetic particles and said (b) particles having an average particle size up to about 0.1 micron and being present in a concentration in the range of about 0.02 to about 0.06 parts, by weight, based on the weight of said ferromagnetic particles.
Claim 3
Dependent Claim
47 words
The invention according to claim 1 in which the concentration of said (a) particles is in the range of about 0.01 to about 0.02 parts, by weight, and the concentration of said (b) particles is in the range of about 0.02 to about 0.04 parts, by weight.
Claim 4
Dependent Claim
45 words
The invention according to claim 2 in which said (a) particles have an average particle size in the range of about 0.3 to about 0.8 micron and said (b) particles have an average particle size in the range of about 0.001 to about 0.1 micron.
Claim 5
Dependent Claim
24 words
The invention according to claim 3 in which said ferromagnetic particles are acicular gamma ferric oxide particles and said non-ferromagnetic particles are alumina particles.
Claim 6
Dependent Claim
21 words
The invention according to claim 1 in which said Mohs Hardness is in the range of about 5.5 to about 10.
Claim 7
Dependent Claim
32 words
The invention according to claim 1 in which said ferromagnetic particles are iron oxide particles and said non-ferromagnetic particles have a Mohs Hardness in the range of about 7 to about 9.3.
Claim 8
Dependent Claim
18 words
The invention according to claim 6 in which said iron oxide particles are acicular gamma ferric oxide particles.
Claim 9
Dependent Claim
27 words
The invention according to claim 1 in which said (a) particles are alumina, silicon, silicon carbide, silicon nitride, boron carbide, boron nitride or chromium (III) oxide particles.
Claim 10
Dependent Claim
14 words
The invention according to claim 8 in which said (a) particles are alumina particles.
Claim 11
Dependent Claim
14 words
The invention according to claim 9 in which said (b) particles are alumina particles.
Claim 12
Dependent Claim
15 words
The invention according to claim 8 in which said (a) particles are silicon carbide particles.
Claim 13
Dependent Claim
14 words
The invention according to claim 8 in which said (b) particles are alumina particles.
Claim 14
Dependent Claim
17 words
The invention according to claim 12 in which said ferromagnetic particles are acicular gamma ferric oxide particles.
Claim 15
Dependent Claim
26 words
The invention according to claim 1 in which said ferromagnetic particles have an average particle size in the range of about 0.3 to about 0.7 micron.
Claim 16
Dependent Claim
17 words
The invention according to claim 14 in which said ferromagnetic particles are acicular gamma ferric oxide particles.
Claim 17
Dependent Claim
34 words
The invention according to claim 15 in which said (a) particles are alumina, silicon, silicon carbide, silicon nitride, boron carbide, boron nitride or chromium (III) oxide particles and said (b) particles are alumina particles.
Claim 18
Dependent Claim
38 words
The invention according to claim 1 in which said element comprises at least two superimposed magnetic recording layers and said magnetic recording layer of claim 1 is the outermost magnetic recording layer with respect to said non-magnetic support.
Claim 19
Dependent Claim
18 words
The invention of claim 1 in which said magnetic recording layer also comprises a carbonic acid ester lubricant.
Claim 20
Dependent Claim
14 words
The invention according to claim 18 in which said lubricant is ethyl cetyl carbonate.
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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) | 1980-03-28 | 1980-09-27 | 1981-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-28 | 1984-09-27 | 1985-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-28 | 1988-09-27 | 1989-03-29 | $7700.00 | Window Closed / Lapsed |