| 摘要 |
PURPOSE:To surely produce the toner which is small in grain size and has a sharp grain size distribution by decreasing the circumferential speed of the rotating body of a dispersing machine to <=40% of an initial circumferential speed when a polymn. conversion rate attains 40 to 80%. CONSTITUTION:A polymn. monomer contg. at least a polymerizable monomer, coloring agent and polymn. initiator is first prepd. This polymn. monomer is then added into a dispersion medium contg. magnetic powder as a dispersion stabilizer. While the temp. of this mixture system is risen up to a polymn. temp., the rotating body of the dispersing machine is rotated to start a polymn. reaction while the polymn. monomer is dispersed in the dispersion medium. Further, the circumferential speed (secondary circumferential speed) V2 of the rotating body of the dispersing machine is lowered down to <=40%, more preferably <=30% of the initial circumferential speed (primary circumferential speed) V1 and the polymn. reaction is further continued when the polymn. conversion rate attains 40 to 80%, more preferably 40 to 60%. Then, the collision probability of liquid drops decreases and the coalescence of the liquid drops is suppressed to decrease the appearance of the maximal particles. Since the shearing force by the rotating body decreases, the fission of the liquid drops is suppressed and the appearance of the minimal particles decreases. The grain size distribution is eventually sharpened. |
