INTERACTION BETWEEN POLYMERS AND MAGNETIC PARTICLES - EFFECT ON THE PROPERTIES OF PARTICULATE MAGNETIC RECORDING MEDIA

The interaction between vinyl chloride-vinyl acetate-vinyl alcohol copolymers and cobalt-modified gamma-Fe2O3 (Co-gamma-Fe2O3) magnetic particles has been studied. Adsorption isotherms and heats of adsorption were measured for polymers with various kinds and concentrations of functional groups. The interaction of the polymer with Co-gamma-Fe2O3, and the amount of polymer adsorbed, increased in proportion to the hydroxy-group concentration of the polymer. Introducing a few carboxy groups into the polymer also produced stronger interaction. This interaction affected the properties of particulate magnetic recording media considerably. The interaction strength of the polymer with Co-gamma-Fe2O3 has been shown to determine the Young's modulus of a magnetic coating layer. Stronger interaction led to higher dispersibility of Co-gamma-Fe2O3 in the magnetic coating layer.