Magnetic recording medium
AssigneeFuji Photo Film Co., Ltd.
InventorsShinji Saito, Nobuo Yamazaki
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Abstract
The present invention provides a magnetic recording medium comprising a nonmagnetic layer mainly having an inorganic nonmagnetic particle dispersed in a binder provided on a nonmagnetic flexible support and a magnetic layer having a ferromagnetic particle dispersed in a binder, characterized in that the magnetic layer comprises a hexagonal ferrite magnetic material and exhibits a thickness of 1 .mu.m or less, or 2.5 .mu.m or less in total if there are a plurality of magnetic layers, a central line average surface roughness of 0.006 .mu.m or less, SFD of 0.3 or less in the longitudinal direction on the plane and Br/Hc of less than 1.5, whereby the short wavelength recording can be remarkably improved in electro-magnetic conversion characteristics, particularly 7 MHz output.
Claims19
A magnetic recording medium comprising a nonmagnetic layer having a nonmagnetic particle dispersed in a binder provided on a nonmagnetic flexible support and a magnetic recording layer having a magnetic material dispersed in a binder provided on the nonmagnetic layer, wherein the magnetic layer comprises a hexagonal ferrite magnetic material and has a thickness of 1 .mu.m or less, a central line average surface roughness at a cut off value of 0.08 mm of 0.006 .mu.m or less, a switching field distribution of 0.3 or less in the longitudinal direction, a coercive force of 1,000 to 4,000 Oe and a ratio of residual magnetic flux density to coercive force of less than 1.5.
A magnetic recording medium comprising a first magnetic layer having a ferromagnetic acicular particle dispersed in a binder provided on a nonmagnetic flexible support and a second magnetic layer having a magnetic material dispersed in a binder provided on the first magnetic layer, wherein the second magnetic layer comprises a hexagonal ferrite magnetic material, the total thickness of the magnetic layers is 2.5 .mu.m or less, and the second magnetic layer has a central line average surface roughness at a cut off value of 0.08 mm of 0.006 .mu.m or less, a switching field distribution of 0.3 or less in the longitudinal direction, a coercive force of 1,000 to 4,000 Oe and a ratio of residual magnetic flux density to coercive force of less than 1.5.
A magnetic recording medium comprising a nonmagnetic layer having a nonmagnetic particle dispersed in a binder provided on a nonmagnetic flexible support and first and second magnetic layers having a magnetic material dispersed therein provided on the nonmagnetic layer in this order, wherein the first magnetic layer comprises a ferromagnetic acicular particle, the second magnetic layer comprises a hexagonal ferrite magnetic material, the total thickness of the magnetic layers is 2.5 .mu.m or less and the second magnetic layer has a central line average surface roughness at a cut off value of 0.08 mm of 0.006 .mu.m or less, a switching field distribution of 0.3 or less in the longitudinal direction, a coercive force of 1,000 to 4,000 Oe and a ratio of residual magnetic flux density to coercive force of less than 1.5.
Dependencies are inferred from the claim text.