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AssigneeToda Kogyo Corporation
InventorsKazuyuki Hayashi, Yasuyuki Tanaka, Keisuke Iwasaki, Hiroko Morii
Estimating the term…
Acicular hematite particles of the present invention comprise an average major axis diameter of 0.004 to 0.295 μm, a geometrical standard deviation of minor axis diameter of not more than 1.35 and a pH value of not less than 8, and containing not more than 300 ppm of soluble sodium salt, calculated as Na and not more than 150 ppm of soluble sulfate, calculated as SO4. Such acicular hematite particles are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which exhibits a low light transmittance, an excellent smooth surface and a high strength, and can be prevented from being deteriorated in magnetic properties due to the corrosion of magnetic acicular metal particles containing iron as a main component which are dispersed in a magnetic recording layer thereof.
Acicular hematite particles comprising an average major axis diameter of 0.004 to 0.295 μm, a geometrical standard deviation of minor axis diameter of not more than 1.35 and a pH value of not less than 8, and containing not more than 300 ppm of soluble sodium salt, calculated as Na and not more than 150 ppm of soluble sulfate, calculated as SO4.
A magnetic recording medium comprising:
A non-magnetic substrate comprising:
Dependencies are inferred from the claim text.