PURPOSE: To improve the magnetic characteristics, electromagnetic conversion characteristics, surface smoothness and durability of a magnetic layer by incorporating magnetic powder treated with a specified surface treating agent and a specified binder into the magnetic layer.
CONSTITUTION: The magnetic powder is treated with a surface treating agent comprising a silane coupling agent having polar groups and another silane coupling agent having no polar group, by the amt. of 0.1-5.0pts.wt. of the treating agent to 100pts.wt. of the powder. The treated magnetic powder and the binder having polar groups are incorporated by the ratio of 90:10-5:95 into the magnetic layer. By this method, the number of the polar groups in the coupling agent can be controlled to avoid an excess state and the surface energy of the magnetic powder can be reduced. This prevents flocculation of the magnetic powder and enhances the affinity to the binder, which enhances the dispersion effect of the powder in the binder. Thus, the magnetic layer has improved magnetic characteristics, electromagnetic conversion characteristics, surface smoothness and durability.
UEHARA TAKAYUKI
SASAZAWA KAZUO
Next Patent: POLARIZATION MULTIPLEX RECORDING METHOD