Zeon Corporation

Junichi Takashima

Takashi Iga

Fuminari Oyama

Keita Sensui

Kojiro Akazaki

Ryo Tsumura

A toner which is less likely to cause toner leakage and which is less likely to cause aggregation after being left to stand under a high temperature condition. A toner for developing electrostatic images, comprising colored resin particles comprising a binder resin and a colorant, and an external additive, wherein a conditioned bulk density obtained by a powder flowability analyzing device is from 0.525 g/mL to 0.565 g/mL.

Toner for developing electrostatic images

The present invention is to provide a toner production method configured to prevent scale formation, be resistant to pipe clogging, and realize stable and efficient toner production, even in the case of long-term continuous production. Disclosed is a toner production method comprising: a dispersing step for obtaining a colorant dispersion by, in a stirring tank, (a) dispersing or dissolving a colorant and a charge control agent in a polymerizable monomer, or (b) dispersing or dissolving a binder resin, a colorant and a charge control agent in an organic solvent, and a droplets forming step by suspending the colorant dispersion in an aqueous dispersion medium, wherein, in the dispersing step, the binder resin, colorant or charge control agent is added to the polymerizable monomer or organic solvent in the stirring tank, from a hopper, through a pipe heated by a heating device.

Toner production method

A method for producing a polymerized toner comprising a step of polymerizing a polymerizable monomer composition in an aqueous dispersion medium in the presence of a polymerization initiator to obtain a dispersion liquid of colored polymer particles and a stripping step of injecting a gas comprised of air or an inert gas into the dispersion liquid of the colored polymer particles while stirring the dispersion liquid in an evaporator and the flow rate of the gas injected per weight of the colored polymer particles being 0.05 to 4 L/(hr&#xb7;kg), the pressure of the vapor phase of the evaporator being 5 to 80 kPa.

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Tokyo, Japan

Junichi Takashima