US4474848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1982-04-13
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Granted: 1984-10-02
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Expires: 2002-04-13
Abstract
Abstract This invention relates to an improved magnetic recording medium having an increased durability as well as a decreased head abrasion, which comprises a magnetic recording layer on the surface of a non-magnetic support, the magnetic recording layer containing a ferromagnetic powder, an abrasive having a Mohs' hardness of at least 6, a non-magnetic powder which is granular alpha -Fe2O3 and a fatty acid and fatty acid ester.
Inventors
- 👤 Nobutaka Yamaguchi
- 👤 Masaaki Fujiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:10
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; G11B5/71; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
143 words
A magnetic recording medium comprising a magnetic recording layer on the surface of a non-magnetic support, the magnetic recording layer comprising (i) a ferromagnetic powder, (ii) 1-10% by weight based on the weight of the ferromagnetic powder of an abrasive having a Mohs' hardness of at least 6 and a mean particle size of 0.05 to 5 microns (iii) 5-30% by weight based on the weight of the ferromagnetic powder of a non-magnetic powder which is granular α-Fe 2 O 3 having a mean particle size of 0.2 to 1 micron and (iv) 0.1-2% by weight based on the weight of the ferromagnetic powder of a saturated or unsaturated fatty acid having 6 to 22 carbon atoms and 0.1-2% by weight based on the weight of the ferromagnetic powder of a fatty acid ester having a melting point of at most 60° C.
Claim 2
Dependent Claim
143 words
A magnetic recording medium comprising a magnetic recording layer on the surface of a non-magnetic support, the magnetic recording layer comprising (i) a ferromagnetic powder, (ii) 1-10% by weight based on the weight of the ferromagnetic powder of an abrasive having a Mohs' hardness of at least 6 and a mean particle size of 0.05 to 5 microns (iii) 5-30% by weight based on the weight of the ferromagnetic powder of a non-magnetic powder which is granular α-Fe 2 O 3 having a mean particle size of 0.2 to 1 micron and (iv) 0.1-2% by weight based on the weight of the ferromagnetic powder of a saturated or unsaturated fatty acid having 6 to 22 carbon atoms and 0.1-2% by weight based on the weight of the ferromagnetic powder of a fatty acid ester having a melting point of at most 60° C.
Claim 3
Dependent Claim
88 words
The magnetic recording medium of claim 1, wherein the ferromagnetic powder is selected from the group consisting of fine powders of γ-Fe 2 O 3 , Co-doped γ-Fe 2 O 3 , Fe 3 O 4 , Co-doped Fe 3 O 4 , Berthollide compounds of γ-Fe 2 O 3 and Fe 3 O 4 , Co-doped Berthollide compounds of γ-Fe 2 O 3 and Fe 3 O 4 , CrO 2 , Co-Ni-P alloys, Co-Ni-Fe alloys, Co-Ni-Fe-B alloys, Fe-Ni-Zn alloys, Fe-Mn-Zn alloys, Fe-Co-Ni-P alloys and Ni-Co alloys.
Claim 4
Dependent Claim
40 words
The magnetic recording medium of claim 1, wherein the abrasive having a Mohs' hardness of at least 6 is selected from the group consisting of fused alumina, silicon carbide, chromium oxide, corundum, synthetic corundum, diamond, synthetic diamond, garnet and emery.
Claim 5
Dependent Claim
36 words
The magnetic recording medium of claim 1, wherein the saturated or unsaturated fatty acid is selected from the group consisting of capric acid, lauric acid, myristic acid, oleic acid, stearic acid, erucic acid and behenic acid.
Claim 6
Dependent Claim
44 words
The magnetic recording medium of claim 1, wherein the fatty acid having a melting point of at most 60° C. is selected from the group consisting of methyl stearate, ethyl stearate, butyl stearate, amyl stearate, butyl palmitate, butyl myristate, oleyl oleate and butyl laurate.
References Cited (Backward Citations)
US3833412A
Cited
US3959553A
Cited
US4110503A
Cited
US4172176A
Cited
US4275115A
Cited
US4322474A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-02 | 1988-04-02 | 1988-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-02 | 1992-04-02 | 1992-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-02 | 1996-04-02 | 1996-10-02 | $7700.00 | Window Closed / Lapsed |