PURPOSE: To prevent the formation of latex during a polymn. reaction, to enhance work efficiency and to increase the blackening density of a toner by suspension-polymerizing a monomer dispersed in an aqueous medium contg. a water-soluble mercaptan compound and by adding the resulting polymer particles.
CONSTITUTION: This toner contains polymer particles obtd. by polymerizing a 3W25C monomer having a polymerizable unsatd. group in an aqueous medium in the presence of a water-soluble mercaptan compound and a water-soluble high-molecular compound and/or a slightly water-soluble inorg. salt. The water- soluble mercaptan compound is used so as to inhibit emulsion polymn. in the aqueous phase, and the amount of the compound added is 0.001W10wt%, preferably 0.05W5wt% of the amount of water as the dispersion medium. Styrene, a styrene deriv. such as o-methylstyrene, an acrylic acid deriv. such as methyl acrylate, a methacrylic acid deriv. such as ethyl methacrylate or a vinyl ester such as vinyl acetate may be used as the monomer having a polymerizable unsatd. group.
TAKEMURA KAZUNARI
FUKUYAMA YUKIHIRO
