PRODUCTION OF MAGNETIC METALLIC POWDER SUBJECTED TO SURFACE TREATMENT

摘要

PURPOSE:To produce magnetic metallic powder having excellent dispersibility under hydrophobic conditions by dispersing the magnetic metallic powder having a specific differential thermal curve with an electrolyte soln. having specific pH and treating the powder with a surface active agent soln. having a reversed polarity. CONSTITUTION:This invention relates to magnetic metallic powder to be used for a magnetic recording medium. The outside surface of magnetic metallic powder (Fe-Ni-Co alloy, etc.) is coated with a thermally stable hydrophilic high polymer and the magnetic metallic powder of which the differential thermal curve does not change at least up to 80 deg.C is thus obtd. Such magnetic metallic powder is dispersed into an electrolyte soln. (NaOH, etc.) having 3.5-13.0pH value. The electrolyte soln. is used at about 20-5,000ml by 100g the magnetic powder. The magnetic powder is then treated with a surface active agent having the electric charge reverse to the electric charge of the magnetic powder. The surface active powder is used at about 0.05-50pts.wt. by 100pts.wt. the magnetic powder and is used by being mixed with water or hydrophilic solvent.