Magnetic recording medium
First Claim
1. A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder formed on the lower layer, which is a magnetic recording medium for recording signals having areal recording density of from 0.20 to 2 G bit/inch2, wherein the coercive force of said magnetic layer is 1,800 Oe or more, the average long axis length of said ferromagnetic metal powder is 0.15 μ
- m or less, the average particle size of said ferromagnetic hexagonal ferrite powder is 0.10 μ
m or less;
the dry thickness of said magnetic layer is from 0.05 to 0.30 μ
m, φ
m is from 10.0×
10−
3 to 1.0×
10−
3 emu/cm2, and wherein said magnetic layer has a central plane average surface roughness of 5.0 nm or less measured by a 3D-MIRAU method.
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Accused Products
Abstract
A magnetic recording medium is disclosed, which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder formed on the lower layer, which is a magnetic recording medium for recording signals having areal recording density of from 0.17 to 2 G bit/inch2, wherein the coercive force of the magnetic layer is 1,800 Oe or more, the average long axis length of the ferromagnetic metal powder is 0.15 μm or less, and the average particle size of the ferromagnetic hexagonal ferrite powder is 0.10 μm or less; or wherein the dry thickness of the magnetic layer is from 0.05 to 0.30 μm, φm is from 10.0×10−3 to 1.0×10−3 emu/cm2, and the coercive force of the magnetic layer is 1,800 Oe or more.
The object of the present invention is to provide a magnetic recording medium which is markedly improved in electromagnetic characteristics, particularly, high density recording characteristics, and is excellent in durability: and to provide a high capacity magnetic recording medium, in particular, a disc-like magnetic recording medium, having a high recording capacity of from 0.17 to 2 Gbit/inch2.
206 Citations
37 Claims
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1. A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder formed on the lower layer, which is a magnetic recording medium for recording signals having areal recording density of from 0.20 to 2 G bit/inch2, wherein the coercive force of said magnetic layer is 1,800 Oe or more, the average long axis length of said ferromagnetic metal powder is 0.15 μ
- m or less, the average particle size of said ferromagnetic hexagonal ferrite powder is 0.10 μ
m or less;
the dry thickness of said magnetic layer is from 0.05 to 0.30 μ
m, φ
m is from 10.0×
10−
3 to 1.0×
10−
3 emu/cm2, and wherein said magnetic layer has a central plane average surface roughness of 5.0 nm or less measured by a 3D-MIRAU method. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
- m or less, the average particle size of said ferromagnetic hexagonal ferrite powder is 0.10 μ
Specification