Patent ID: 7763408

Claim:
A method for producing a developing agent comprises: applying a radical polymerizable monomer as a binder resin material in a dispersion medium containing a dispersant selected from the group consisting of an anionic surfactant, a nonionic surfactant and a cationic surfactant and a polymerization initiator to prepare a dispersion of the radical polymerizable monomer; mixing a dispersion containing a coloring agent particle with the dispersion of the radical polymerizable monomer to form a mixture, and adding a reducing agent selected from iron(II) sulfate and iron(II) chloride to the mixture to polymerize the dispersed radical polymerizable monomer by the action of a generated radical, thereby not only forming a binder resin fine particle but coagulating the binder resin fine particle and the coloring agent particle to form a coagulated particle.