Patent ID: 6248437
Filing Date: 2001-06-19
Classification: B82Y,C01G,C01P,G11B,Y10S,Y10T

Abstract:
A magnetic recording medium comprising: a non-magnetic substrate; a non-magnetic undercoat layer comprising a coating film composition comprising non-magnetic acicular hematite particles and a binder resin, which is formed on said non-magnetic substrate; and a magnetic recording layer comprising a coating film composition comprising magnetic particles containing iron as a main ingredient and a binder resin, which is formed on said non-magnetic undercoat layer,wherein said non-magnetic acicular hematite particles contain 0.05 to 50 wt % of aluminum, calculated as Al, approximately uniformly within the particles, have an average major axial diameter of not more than 0.3 .mu.m, a pH value of said particles of not less than 8, and contain soluble sodium salts of not more than 300 ppm soluble sodium, calculated as Na, and soluble sulfates of not more than 150 ppm soluble sulfate, calculated as SO.sub.4 ; and wherein said magnetic particles containing iron as a main ingredient comprising iron and aluminum of 0.05 to 10% by weight, calculated as Al.