Patent ID: 6627293
Filing Date: 2003-09-30
Classification: G11B,Y10T

Abstract:
A magnetic recording medium comprising:a non-magnetic support body; a lower undercoat layer coating said non-magnetic support body and comprising a non-magnetic paint which comprises a binder and a non-magnetic powder; and an upper magnetic layer formed on the lower undercoat layer wherein, said non-magnetic powder includes a needle-shaped non-magnetic pigment whose surface has an area coated with graphite-shaped crystals of carbon black; and said non-magnetic powder is prepared by mechanochemical processing of said carbon black in an amount of 10 wt % to 40 wt % with respect to said non-magnetic pigment; wherein said lower undercoat layer has a thickness in a range of 0.2 &mgr;m to 3.0 &mgr;m; wherein said non-magnetic pigment is hematite (a -Fe203); wherein said carbon black has an average primary particle diameter not exceeding 80 nm and a DBP oil absorption amount not exceeding 180 ml/100 cc wherein said undercoat layer has centerline average surface roughness of 4.2 nm or less; and wherein said lower undercoat layer and said upper magnetic layer together have a Young's modulus of 5.0 GPa to 15.0 GPa at room temperature.