To provide a high-capacity magnetic recording disk which is set with a smaller track width and a smaller sector number and is adequate for a recording and reproducing system allowing the substantial increase of a recording capacity by suppressing the anisotropy of thermal shrinkage when the magnetic recording disk is exposed to a high temp.
This magnetic recording disk is constituted by disposing a lower layer which is substantially nonmagnetic and a magnetic layer formed by dispersing ferromagnetic metallic powder or ferromagnetic hexagonal ferrite powder into a binder in this order on a base. In such a case, the magnetic recording disk is ≤0.05% in both of the thermal shrinkage rate anisotropy when the disk is placed for 30 minutes under the absolute dry environment at 80°C and the thermal shrinkage rate anisotropy when the disk is placed for 72 hours under the absolute dry environment at 80°C. In addition, the number of the servo sectors existing on one track is 80 to 150 pieces. The magnetic recording disk is used as the recording and reproducing system set at ≤10 μm in the track width.
TAKAHASHI MASATOSHI
NOGUCHI HITOSHI
SAITO SHINJI
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