US4275115A
Expired / Lapsed
US
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Magnetic recording composition and article coated therewith
Assignee: Victor Company of Japan Ltd
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Filing: 1979-04-27
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Granted: 1981-06-23
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Expires: 1999-04-27
Abstract
Abstract A magnetic recording composition comprising a non-aqueous dispersion, in liquid dispersion medium, of a dispersed solid phase of a major proportion of magnetic powder and minor proportions of at least two types of non-magnetic powder. One type of the non-magnetic powder has a Mohs' hardness of greater than 7, inclusive, and is contained in an amount of from 1 to 5 wt% of the magnetic powder. The other type of the non-magnetic powder has a Mohs' hardness of smaller than 7 but greater than about 3 and is contained in an amount of from 1 to 15 wt% of the magnetic powder. Either one type or the other type of the non-magnetic powder can be composed of two different kinds of non-magnetic materials whose total amount should be within the above-recited range.
Inventors
- 👤 Tunehide Naruse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:33
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; Y10T428/256; Y10T428/257; Y10T428/26; Y10T428/269
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
138 words
A magnetic recording composition comprising a non-aqueous dispersion, in a liquid dispersion medium, of a dispersed solid phase of a major proportion of a magnetic powder and a minor proportion of a three-component non-magnetic powder system comprised of two types of non-magnetic powders each having an average particle size below 2μ, one type having a Mohs' hardness greater than or equal to 7 and being contained in an amount of from 1 to 5 wt.% of said magnetic powder; and the other type having a Mohs' hardness less than 7 but greater than about 3 and being contained in an amount of from 7 to 15 wt.% of said magnetic powder; said three-component system being comprised of two kinds of said one type of the non-magnetic powders and one kind of said other type of the non-magnetic powders.
Claim 2
Dependent Claim
138 words
A magnetic recording composition comprising a non-aqueous dispersion, in a liquid dispersion medium, of a dispersed solid phase of a major proportion of a magnetic powder and a minor proportion of a three-component non-magnetic powder system comprised of two types of non-magnetic powders each having an average particle size below 2μ, one type having a Mohs' hardness greater than or equal to 7 and being contained in an amount of from 1 to 5 wt.% of said magnetic powder; and the other type having a Mohs' hardness less than 7 but greater than about 3 and being contained in an amount of from 7 to 15 wt.% of said magnetic powder; said three-component system being comprised of two kinds of said one type of the non-magnetic powders and one kind of said other type of the non-magnetic powders.
Claim 3
Dependent Claim
33 words
A magnetic recording composition according to claim 1 wherein said three-component system is comprised of alumina and Cr 2 O 3 as said one type, and of zinc ferrite as said other type.
Claim 4
Dependent Claim
32 words
A magnetic recording composition according to claim 1 wherein said three-component system is comprised of silicon carbide and titanium oxide as said one type, and of α-iron oxide as said other type.
Claim 5
Dependent Claim
27 words
A magnetic recording composition according to claim 1 wherein said one type is contained in an amount of from 3 to 5 wt.% of said magnetic powder.
Claim 6
Dependent Claim
164 words
A magnetic recording composition comprising a non-aqueous dispersion, in a liquid dispersion medium, of a dispersed solid phase of a major proportion of a magnetic powder and a minor proportion of a three-component non-magnetic powder system comprised of two types of non-magnetic powders each having an average particle size below 2μ, one type having a Mohs' hardness greater than or equal to 7 and being contained in an amount of from 2 to 5 wt.% of said magnetic powder; and the other type having a Mohs' hardness of less than 7 but greater than about 3 and being contained in an amount of from 6 to 15 wt.% of said magnetic powder; said three-component system comprised of one kind of said one type of the non-magnetic powders and two kinds of said other type of the non-magnetic powder; wherein said three-component system is comprised of Cr 2 O 3 as said one type, and of zinc ferrite and calcium carbonate as said other type.
Claim 7
Dependent Claim
164 words
A magnetic recording composition comprising a non-aqueous dispersion, in a liquid dispersion medium, of a dispersed solid phase of a major proportion of a magnetic powder and a minor proportion of a three-component non-magnetic powder system comprised of two types of non-magnetic powders each having an average particle size below 2μ, one type having a Mohs' hardness greater than or equal to 7 and being contained in an amount of from 2 to 5 wt.% of said magnetic powder; and the other type having a Mohs' hardness of less than 7 but greater than about 3 and being contained in an amount of from 6 to 15 wt.% of said magnetic powder; said three-component system comprised of one kind of said one type of the non-magnetic powders and two kinds of said other type of the non-magnetic powder; wherein said three-component system is comprised of Cr 2 O 3 as said one type, and of zinc ferrite and calcium carbonate as said other type.
Claim 8
Dependent Claim
17 words
A magnetic video recording article comprising a base coated with the composition of claim 1 or 5.
Claim 9
Dependent Claim
16 words
A magnetic video recording article according to claim 6 wherein said base is a polyester film.
References Cited (Backward Citations)
US3687725A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-22 | 1984-12-22 | 1985-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-22 | 1988-12-22 | 1989-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-22 | 1992-12-22 | 1993-06-23 | $7700.00 | Window Closed / Lapsed |