Patent ID: 8372573
Filing Date: 2013-02-12
Classification: G03G

Abstract:
1. A process for preparing a toner comprising the steps of: forming a first liquid dispersion by dispersing a colored particle into an aqueous medium containing a sparingly water-soluble inorganic dispersant, the colored particle comprising a binder resin, a colorant and a wax, in which a surface of the colored particle is coated with the sparingly water-soluble inorganic dispersant; adding an elastic material particle to the first liquid dispersion, and forming a second liquid dispersion in which the colored particle whose surface is coated with the elastic material particle is dispersed, the sparingly water-soluble inorganic dispersant existing between the surface of the colored particle and the elastic material particle; heating the second liquid dispersion to soften the colored particle and the elastic material particle; and removing the sparingly water-soluble inorganic dispersant by dissolving into the aqueous medium while maintaining softened state of the colored particle and the elastic material particle and forming a coat layer made from the elastic material particle coating the colored particle directly, wherein the colored particle has a glass transition point (Tt) from 25.0° C. to 60.0° C. and the elastic material particles has a glass transition point (Ts) from 40.0° C. to 90.0° C., wherein Ts−Tt is from 5.0° C. to 50.0° C., wherein the elastic material particle has a zeta potential (Z1p) of from −110.0 mV to −35.0 mV; a dispersoid which has the colored particle and the sparingly water-soluble inorganic dispersant in the step of forming the first liquid dispersion, having a zeta potential Z2t (mV) of −15.0 mV or less; and a difference between the Z2t and the Z1p, Z2t−Z1p, of from 5.0 mV to 50.0 mV, wherein the toner comprises (a) a toner base particle containing at least the binder resin, the colorant and the wax, and an elastic material with which the toner base particle is coated on its surface and which is made from the elastic material particle, and (b) an inorganic fine powder, wherein in a loss tangent (tan δ) curve obtained by a dynamic viscoelasticity test of the toner, the tan δ showing a maximal value δa in the temperature region of from 28.0° C. to 60.0° C., which maximal value δa is 0.50 or more, and showing a minimal value δb in the temperature region of from 45.0° C. to 85.0° C., which minimal value δb is 0.60 or less, where the difference between the maximal value δa and the minimal value δb, δa−δb, is 0.20 or more; and, where the temperature that affords the maximal value δa is represented by Ta (° C.) and the temperature that affords the minimal value δb is represented by Tb (° C.), the difference between the Ta and the Tb, Tb−Ta, being from 5.0° C. to 45.0° C., and wherein the toner has, in a storage elastic modulus (G′) curve obtained by the dynamic viscoelasticity test, a value G′a of a storage elastic modulus at the Ta, of from 1.00×106 Pa to 5.00×10