| 摘要 |
PROBLEM TO BE SOLVED: To obtain a magnetic recording medium small in light transmittance, smooth in surface state, high in strength and excellent in durability, and to industrially obtain an acicular hematite particle powder, which is capable of suppressing the corrosion of magnetic metallic particle powder consisting essentially of iron in a magnetic layer and is adequate for the nonmagnetic ground layer of the magnetic recording medium. SOLUTION: The hematite particle power for the nonmagnetic ground surface layer of the magnetic recording medium formed by using the magnetic metallic particle power consisting essentially of the iron is the acicular hematite particle power which consists of the acicular hematite particles uniformly contg. aluminum in the particles and in which the pH value of the powder is >=8, the content of a soluble sodium salt is <=300ppm in terms of Na and the content of soluble sulfate is <=150ppm in terms of So4 . |
