| 摘要 |
PROBLEM TO BE SOLVED: To enable high density recording and to improve electromagnetic conversion characteristics by adding carbon black as a solid lubricant, specifying the average particle diameter of the carbon black and its add amt. to specified ranges. SOLUTION: This magnetic recording medium is provided with a magnetic layer 2 on a nonmagnetic supporting body 1 and forming a back coating layer on the back surface of the nonmagnetic supporting body 1. The magnetic powder included in the magnetic layer 2 has <=0.1μm major axial length. Carbon black added as a solid lubricant to the magnetic layer 2 has 200 to 400nm average particle diameter and is added by 0.5 to 4 pts.wt. to 100 pts.wt. of the magnetic powder. The surface roughness SRa of the nonmagnetic supporting body where the magnetic layer 2 is formed is about 10nm measured by critical angle focus error detection method. Therefore, the frictional coefft. can be controlled to a range which does not cause any problems for practical use without decreasing the electromagnetic conversion characteristics.
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