Toner, developing device, and process cartridge

Patent metadata

Field	Value
Publication number	US-9971260-B2
Application number	US-201615270655-A
Country	US
Kind code	B2
Filing date	Sep 20, 2016
Priority date	Jan 15, 2014
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

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 formula (1) and (2):

2/3≤ T/Dv ≤1.5  (1)

1/3≤ 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.

First claim

What is claimed is:

1. A toner, comprising:
an external additive; and
mother toner particles, comprising:
a binder resin;
a release agent; and
a plurality of fine resin particles on the mother toner particle surface, each fine resin particle composed of a vinyl polymeric resin;
wherein when a plurality of the toner particles are observed in a scanning transmission electron microscope a first amount by number of the toner particles satisfy formula (1) and a second amount by number of the toner particles satisfying formula (1) also satisfy formula (2) and a number % of the amount of second toner particles of the first amount of toner particles is from 20% to 80%:
2/3 ≤T/Dv≤ 1.5  (1)

1/3 ≤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, and
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.

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 fine resin particle is half embedded in the surface of the mother particle to form surface asperity thereon.

5. The toner according to claim 1 , wherein the binder resin comprises a polyester-vinyl hybrid resin.

6. A developing device, comprising:
a developer bearer having a surface in contact with the toner according to claim 1 to be supplied to a latent image bearer; and
a developer supply member to supply the toner to the surface of the developer bearer.

7. A process cartridge detachably mountable on an image forming apparatus, comprising:
a latent image bearer to bear a latent image; and
the developing device according to claim 6 to develop the latent image with the toner.

Assignees

• Nozaki Tsuyoshi
• Ishikawa Yoshimichi
• Miki Tomoharu
• Takeuchi Yuta
• Ricoh Co Ltd

Inventors

• Nozaki Tsuyoshi
• Ishikawa Yoshimichi
• Miki Tomoharu
• Takeuchi Yuta

Classifications

• G03G9/08724

  Polyvinylesters · CPC title

• G03G9/0804

  whereby the components are brought together in a liquid dispersing medium · CPC title

• G03G15/08

  using a solid developer, e.g. powder developer · CPC title

• G03G9/08755

  Polyesters · CPC title

• G03G9/09733

  Organic compounds (G03G9/08782 takes precedence) · CPC title