PURPOSE: To easily obtain a coated type vertical recording medium made of particles of oxide type magnetic powder, by forming the magnetic layer of the medium in such a way that a coating material composed of magnetic powder, thermosetting or thermoplastic high-molecular compound, and solvent is applied to the surface of a base body and the coating material is dried by putting the base body coated with the coating material in a magnetic field so that the line of magnetic force of the field passes through the base body perpendicularly.
CONSTITUTION: Minute particles (particle diameter: 0.3μm) of barium ferrite are used as the magnetic powder for this purpose and the magnetic powder is applied to a base body to a film thickness of 6μm. Then the base body coated with the magnetic powder is put in a magnetic field for post treatment and a uniform magnetic field 3,000 Oe produced between two magnets or between pole pieces of two electromagnets is used as an impressing magnetic field. By increasing the intensity of the impressing magnetic field, the degree of orientation can be improved remarkably and the degree of orientation can be improved further when an AC current is superposed upon the exciting current of the electromagnets and the particles are vibrated by an AC magnetic field. The same effect can be obtained effectively, when an ultrasonic wave (20kHz) is applied.
MAEDA MIYOZOU
SHIYOUNO KEIJI
YAMAGISHI WATARU
Next Patent: JPS6063729