| 摘要 |
PURPOSE:To obtain powder of magnetic particles having excellent dispersibility by sticking oxides or hydroxide containing Al or Si or Al and Si to the surface of magnetic particles. CONSTITUTION:These are powder magnetic particles for magnetic recording wherein an oxide or hydroxide containing Al or Si or Al and Si is stuck to the surface of magnetic particles having more than 0.50 of molecular weight dependent parameter alpha in As=K1M<alpha> which is valid from the relation between the molecular weight (M) and saturated amount of absorption (As) of high polymer. In the manufacture of the above, an alkali solution is added to an aqueous suspension of magnetic particles, pH value is made higher than 10, an aqueous solution containing Al or an aqueous solution containing Si or a mixed aqueous solution containing At and Si is added to the suspension, pH value is adjusted to almost neutral, and the hydroxide of Al or Si or both of them is quickly settled. Then, a mixture obtained by screening the magnetic particles and hydroxide by filter is washed with water and dried and treated by consolidation crushing by edge runner, and magnetic power having a high dispersibility can be obtained. |
