Patent ID: 7641991

Claim:
A magnetic recording medium comprising: a non-magnetic support; and at least one magnetic layer above the support, the magnetic layer comprising a ferromagnetic powder dispersed in a binder, the binder comprising a polyurethane resin having a weight-average molecular weight of 200,000 to 400,000, wherein the ferromagnetic powder is an acicular ferromagnetic substance having a major axis length of 20 to 50 nm, a tabular magnetic substance having a particle size of 10 to 50 nm, or a spherical or ellipsoidal magnetic substance having a diameter of 10 to 50 nm, and wherein the polyurethane resin has a weight-average molecular weight (Mw)/number-average molecular weight (Mn) ratio Mw/Mn in the range of 1.0 to 2.5.