ABSTRACT
The magnetic materials were simply milled in the binder, but added surfactant is needed to disperse the magnetic particles. The particles are becoming smaller and the role of the surfactant is becoming more critical. Surfactants are an indispensible part of the coating formulation, and new surfactants are being sought to accommodate the new magnetic materials and the need for yet higher recording densities. The initial role of a surfactant is to deagglommerate particles in the milling process. Afterwards, the function of the surfactant is to uniformly disperse the particles in the binder/solvent matrix. Search for surfactants for use as dispersants for magnetic particles typically involves screening of hundreds of commercial samples. Surfactants presently used include certain GAFAC phosphate ester surfactants. A surfactant manufacturer would be reluctant to develop a product if the only application were in the recording media market.
