PROCESS FOR PRODUCING POLYMER-COATED FERROMAGNETIC PARTICLE, AND POLYMER-COATED FERROMAGNETIC PARTICLE

摘要

Polymer-coated ferromagnetism attained through solving of the problem that because ferromagnetic fine particles tend to aggregate, it is difficult to obtain polymer-coated ferromagnetism resulting from dispersion to a state close to monodispersion and polymer coating. A hydrophobizing substance is adsorbed on hydrophilic ferromagnetic particles to thereby attain hydrophobization. By the use of a surfactant having a nonionic hydrophilic group therein, the ionic strength is suppressed to thereby attain hydrophilization and obtain a dispersion. In the emulsification of monomer liquid, use is made of a nonionic surfactant and an ionic surfactant. The dispersion and the emulsion are mixed together, and an emulsion polymerization is carried out. Thus, a homogeneous stable polymer coating is provided on the well dispersed ferromagnetic particles, thereby obtaining polymer-coated ferromagnetic particles that excel in response to any magnetic field.