| 摘要 |
PURPOSE:To obtain surface treated ferromagnetic powder having good dispersibility and to obtain a magnetic recording medium having good abrasion resistance by dispersing the ferromagnetic powder in an electrolyte soln. and treating the surface with a surface active agent having the electric charge reversed from the electric surface on the powder surface. CONSTITUTION:Ferromagnetic powder is dispersed by a ball mill or the like in a soln. of an electrolyte such as NaOH, Na3Po4 or the like, which electries the surface thereof negative or an electrolyte such as AlCl3, FeCl3 or the like, which electrifies the same positive. The concn. of the electrolyte soln. varies with the kinds of the electrolytes and the isoelectric points of the ferromagnetic powder to be used, and is set at such concn. at which the high pH lower than the isoelectric point of the ferromagnetic powder is attained in order to electrify the ferromagnetic powder positive and negative. After the dispersion, the ferromagnetic powder is treated with the electric charge reversed from the electric charge on the surface thereof, that is, cationic and anionic surface active agents when the surface of the powder is electrified negative and positive. The resulted surface treated ferromagnetic powder exhibits excellent dispersibility, and when the powder is contained in a magnetic powder, a magnetic recording medium having good abrasion resistance is obtd. |
