Patent ID: 7425378

Claim:
A magnetic recording medium comprising: a non-magnetic support, a lower non-magnetic layer comprising at least a non-magnetic powder and a binder resin on one surface of the non-magnetic support, and a magnetic layer comprising at least a ferromagnetic powder and a binder resin on the lower non-magnetic layer, wherein wherein when the magnetic recording medium is subjected to an extraction treatment with water, 7 to 23 μg of PO 4 3− ions are extracted, and 8 to 22 μg of Mg 2+ ions are extracted into the water, per 10 mm 3 of the volume of the lower non-magnetic layer of the magnetic recording medium; and wherein the ferromagnetic powder is a planar hexagonal powder having a coercive force ranging from 79 to 237 kA/m, a saturation magnetization of 50 to 70 Am 2 /kg, an average planar particle size of 30 to 80 and a plate ratio of 3 to 7.