TONER, DEVELOPING DEVICE, AND PROCESS CARTRIDGE
A toner is provided. The toner includes toner particles each including a binder resin and a release agent. From 20% to 80% by number of the toner particles satisfy the following formulae (1) and (2): ⅔≦ T/Dv≦ 1.5 (1) ⅓≦ R/Dv≦ 1.0 (2) wherein Dv represents a volume average particle diameter of the toner particles; and T and R represent the longest cross-sectional diameters of each toner particle and the release agent contained therein, respectively, measured by observing cross-sections of the toner particles with scanning transmission electron microscope.
1 . A toner, comprising:
toner particles, each including:
a binder resin; and
a release agent,
wherein from 20% to 80% by number of the toner particles satisfy the following formulae (1) and (2):
⅔≦ T/Dv≦ 1.5 (1)
⅓≦ R/Rv≦ 1.0 (2)
wherein Dv represents a volume average particle diameter of the toner particles; and T and R represent the longest cross-sectional diameters of each toner particle and the release agent contained therein, respectively, measured by observing cross-sections of the toner particles with scanning transmission electron microscope.
2 . The toner according to claim 1 , wherein the release agent contained in each cross-section of the toner particles has a shape factor SF-1 of from 100 to 140.
3 . The toner according to claim 1 , wherein the toner particles have an average circularity of 0.96 or more.
4 . The toner according to claim 1 , wherein each toner particle include:
an external additive; and
a mother particle including:
the binder resin;
the release agent; and
a plurality of fine resin particles on its surface, each fine resin particle composed of a vinyl polymeric resin,
wherein the mother particle has a sea-island structure in which the fine resin particles serve as island portions and constituents other than the fine resin particles serve as sea portions.
5 . The toner according to claim 4 , wherein each fine resin particle is half embedded in the surface of the mother particle to form surface asperity thereon.
6 . The toner according to claim 1 , wherein the binder resin includes a polyester-vinyl hybrid resin.
7 . A developing device, comprising:
a developer bearer to bear the toner according to claim 1 to be supplied to a latent image bearer; and
a developer supply member to supply the toner to a surface of the developer bearer.
8 . A process cartridge detachably mountable on image forming apparatus, comprising:
a latent image bearer to bear a latent image; and
the developing device according to claim 7 to develop the latent image with the toner.