Patent ID: 8535817
Filing Date: 2013-09-17
Classification: G11B,Y10T

Abstract:
1. A magnetic recording medium comprising a nonmagnetic layer containing a nonmagnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the magnetic layer comprises a nonmagnetic powder of which coefficient of variation CV of a particle size distribution as denoted by the following formula (1): is less than 20 percent, the nonmagnetic powder contained in the magnetic layer is silica powder, the magnetic layer further comprises an inorganic powder other than the silica powder, with a Mohs' hardness of equal to or higher than 6, the magnetic layer contains no carbon black, and the magnetic layer has a thickness being equal to or less than 0.1 μm and falling within a range of 1.1≦φ/t≦8.0, wherein σ denotes the standard deviation of the particle diameter, φ denotes the average particle diameter of the nonmagnetic powder comprised in the magnetic layer expressed in μm, and t denotes the thickness of the magnetic layer expressed in μm.