| 摘要 |
PURPOSE:To improve the dispersibility of powdery magnetic substances, by using an aqueous solution containing at least one of a phosphoric monoester compound, a phosphoric diester compound and their derivatives having specified structures. CONSTITUTION:Powdery magnetic substances such as gamma-Fe2O3, magnetite or bertholide oxide are soaked in an aqueous solution of a surface active agent containing at least one of a phosphoric monoester compound and a phosphoric diester compound shown by the formulae and their derivatives. The solution is agitated for one hour and filtered, and the filtered substances are dried at 110 deg.C for 24hr to obtain magnetic powder for a magnetic recording medium. Since the surface active agent used improves the dispersibility of the powdery magnetic substances and offers excellent thermal stability and low foaming properties, the magnetic characteristics of the magnetic recording medium is also improved. |
