| 摘要 |
PURPOSE:To improve water resistance and moisture resistance and to eliminate hindrance to the storage of records by specifying the pH of a magnetic layer which contains hexagonal system ferrite magnetic powder containing a substituent element within a certain range. CONSTITUTION:When a recording medium is formed, proper amounts of additive, such as magnetic powder, a binder, a dispersant, and a lubricant are scaled and added to a proper solvent to prepare a magnetic paint. The pH of this magnetic paint is measured; when the pH is <=3, an alkaline material is added so that the pH is 3-7 and when >=7, an acidic material is added. Thus, the pH of the magnetic layer is held <=7->=3 to obtain sufficiently satisfactory water resistance and moisture resistance, thereby obtaining the recording medium which has superior running ability and durability. |
