ACICULAR HEMATITE PARTICLE POWDER FOR NONMAGNETIC BASE SURFACE LAYER OF MAGNETIC RECORDING MEDIUM USING MAGNETIC METALLIC PARTICLE POWDER CONSISTING ESSENTIALLY OF IRON, MAGNETIC RECORDING MEDIUM HAVING NONMAGNETIC BASE SURFACE LAYER USING THIS ACICULAR HEMATITE PARTICLE POWDER

摘要

PROBLEM TO BE SOLVED: To obtain a magnetic recording medium having a small light transmittance, smooth surface and high strength and having excellent durability and to industrially obtain acicular hematite particle powder adequate as the powder for the nonmagnetic base surface layer of the magnetic recording medium capable of suppressing corrosion of the magnetic metallic particle powder consisting essentially of iron in a magnetic layer. ;SOLUTION: The hematite particle powder of the nonmagnetic base surface layer of the magnetic recording medium using the magnetic metallic particle powder consisting essentially of the iron is the acicular hematite particle powder which consists of the acicular hematite particle powder uniformly contg. 0.05 to 30 wt.%, in terms of Zr, in the particles and of which the average major axis diameter is 0.3 mm, the power pH value is 8, the content of a soluble sodium salt in terms of Na is 300 ppm and the content of a soluble sulfate in terms of SO₄ is 150 ppm.;COPYRIGHT: (C)1999,JPO