Magnetic particles for magnetic recording medium and process for producing the same

摘要

Magnetic particles suitable for magnetic recording which comprise acicular or plate-like magnetic particles and not less than 0.01 wt% (calculated as Al, SiO2 or Al and SiO2 based on the acicular or plate-like magnetic particles) of an oxide or hydroxide containing Al, Si or both Al and Si adhered to the surfaces of the acicular or plate-like magnetic particles, and which have a value of the molecular-weight-dependent parameter alpha of not less than 0.50, wherein alpha is defined by formula (I) : $wherein:\; M\; is\; the\; number-average\; molecular\; weight\; of\; a\; binder;\; As\; is\; the\; saturation\; adsorption\; of\; the\; binder;\; and\; K1\; is\; a\; constant\; dependent\; on\; the\; binder\; and\; the\; solvent\; used\; for\; measuring\; As.$