As a fundamental study of production of magnetic paint film for high density recording, dispersion of magnetic powder was performed by Bead Mill under various operating conditions, and magnetic paint films were coated with the paint. The dispersibility was evaluated as a coated videotape by glossiness and surface condition. Besides, the electric-power comsumption of agitator was continuously measured during the dispersion operation, and viscosity of the paint was measured.
It was found that high-grade vigeotape is produced by using magnetic paint made around steady power comsumption in dispersion operation. From the results, it was indicated that granulation end-point is around steady power comsumption. And it clarified that in order to obtain well-dispersed metal paint for high-grade videotape at high recording density, dispersion operation should be performed around filling rate of media = 46.3%, peripheral speed of agitator U = 12m/sec.