ELECTROPHOTOGRAPHIC TONER AND METHOD FOR PRODUCING THE SAME

摘要

Disclosed is a decolorizable electrophotographic toner, including: a binder resin; and a colorant which contains at least a color developable compound and a color developing agent and is covered with an outer shell so as to have a capsule structure, wherein the number ratio of particles having an equivalent circle diameter of 0.6 μm or more and 2.5 μm or less of the toner when measured using a flow particle image analyzer after the toner is dispersed in an aqueous medium at a ratio of 0.08% by weight and the resulting dispersion is subjected to a stirring treatment in which stirring is performed at 5000 rpm for 30 minutes using a homogenizer (T-25 digital ULTRA-TURRAX (manufactured by IKA Japan K.K., provided with a shaft generator S25N-10G)) is 30% by number or less.

主权项

1. A method for producing a decolorizable electrophotographic toner, comprising:
mixing a first dispersion liquid in which a colorant is dispersed in an amount such that the content of the colorant in the toner is from 5% to 35% by weight, with a second dispersion liquid in which particles containing at least a binder resin and having a volume average particle diameter of 500 nm or less are dispersed, wherein the colorant contains at least a color developable compound and a color developing agent and is covered with an outer shell so as to have a capsule structure and has a volume average particle diameter of from 0.5 to 3.5 μm, and the binder resin is a polyester-based resin having a weight average molecular weight Mw of 5000 or more and 30000 or less and a glass transition temperature of 52° C. or higher and 80° C. or lower, aggregating the colorant and the particles containing at least the binder resin, thereby obtaining aggregated particles, fusing the aggregated particles at a temperature lower than a completely decolorizing temperature of the colorant, and producing toner particles having a circularity of from 0.88 to 0.95, wherein the toner has the number ratio of particles having an equivalent circle diameter of 0.6 μm or more and 2.5 μm or less of the toner when measured using a flow particle image analyzer after the toner is dispersed in an aqueous medium at a ratio of 0.08% by weight and the resulting dispersion is subjected to a stirring treatment in which stirring is performed at 5000 rpm for 30 minutes using a homogenizer (T-25 digital ULTRA-TURRAX (manufactured by IKA Japan K.K., provided with a shaft generator S25N-10G)) is 30% by number or less.