Toner, developer, toner storage unit, image forming apparatus, and image forming method

Patent metadata

Field	Value
Publication number	US-12529975-B2
Application number	US-202218084579-A
Country	US
Kind code	B2
Filing date	Dec 20, 2022
Priority date	Dec 22, 2021
Publication date	Jan 20, 2026
Grant date	Jan 20, 2026

Abstract

A toner includes toner particles. Each of the toner particles includes a toner base particle including a binder resin, resin particles covering the toner base particle, and zinc stearate particles serving as an external additive. In each of the toner particles, a coverage rate of the toner base particle with the resin particles is 30% or greater and 70% or less. The zinc stearate particles have a volume average particle diameter of 3 μm or greater and 20 μm or less.

First claim

What is claimed is:

1 . A toner comprising:
toner particles, each of the toner particles including:
a toner base particle including a binder resin;
resin particles covering the toner base particle; and
zinc stearate particles serving as an external additive,
wherein, in each of the toner particles, a coverage rate of the toner base particle with the resin particles is 30% or greater and 70% or less, wherein the zinc stearate particles have a volume average particle diameter of 3 μm or greater and 20 μm or less, and wherein an amount of zinc released from the toner is 0.005% by mass or greater and 0.06% by mass or less, where the zinc is derived from the zinc stearate particles.

2 . The toner according to claim 1 ,
wherein the volume average particle diameter of the zinc stearate particles is 5 μm or greater and 15 μm or less.

3 . The toner according to claim 1 ,
wherein the coverage rate of the toner base particle with the resin particles is 40% or greater and 60% or less.

4 . A developer comprising:
a carrier; and the toner according to claim 1 .

5 . A toner storage unit comprising:
the toner according to claim 1 ; and a unit in which the toner is stored.

6 . An image forming apparatus comprising:
an electrostatic latent image bearer; an electrostatic latent image forming unit configured to form an electrostatic latent image on the electrostatic latent image bearer; a developing unit that stores the toner according to claim 1 and is configured to develop the electrostatic latent image with the toner or the developer to form a visible image; a transferring unit configured to transfer the visible image to a recording medium; and a fixing unit configured to fix the visible image transferred to the recording medium.

7 . An image forming method comprising:
forming an electrostatic latent image on an electrostatic latent image bearer; developing the electrostatic latent image with the toner according to claim 1 to form a visible image; transferring the visible image to a recording medium; and fixing the visible image transferred to the recording medium.

8 . The toner according to claim 1 , wherein the toner is negatively charged.

9 . The toner according to claim 1 , wherein the volume average particle diameter of the zinc stearate particles is greater than 10 μm and 20 μm or less.

Assignees

• Yamashita Taishi
• Kitagawa Yohichi
• Takahashi Tsukiko
• Hirose Mitsuaki
• Inoue Daisuke
• Ricoh Co Ltd

Inventors

• Yamashita Taishi
• Kitagawa Yohichi
• Takahashi Tsukiko
• Hirose Mitsuaki
• Inoue Daisuke

Classifications

• G03G9/08711

  with esters of acrylic or methacrylic acid · CPC title

• G03G9/0819

  characterised by the dimensions of the particles · CPC title

• G03G15/0865

  Arrangements for supplying new developer · CPC title

• G03G9/09791 Primary

  Metallic soaps of higher carboxylic acids · CPC title

• G03G15/0168 Primary

  single rotation of recording member to produce multicoloured copy (G03G15/0163 takes precedence) · CPC title