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

Patent metadata

Field	Value
Publication number	US-10599059-B2
Application number	US-201916293691-A
Country	US
Kind code	B2
Filing date	Mar 6, 2019
Priority date	Mar 12, 2018
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

A toner is provided. The toner comprises mother particles and an external additive covering the mother particles. The mother particles comprise a binder resin, and the external additive comprises inorganic particles. The inorganic particles comprise small-size inorganic particles having an equivalent circle diameter of from 30 to 70 nm and large-size inorganic particles having an equivalent circle diameter of from 150 to 200 nm and a circularity of 0.85 or more. The large-size inorganic particles are 20 to 70 in number per 100 μm2 image area of the toner observed with a field-emission scanning electron microscope.

First claim

The invention claimed is:

1. A toner, comprising:
mother particles comprising a binder resin; and
an external additive covering the mother particles, comprising inorganic particles comprising:
small-size inorganic particles having an equivalent circle diameter of from 30 to 70 nm; and
large-size inorganic particles having an equivalent circle diameter of from 150 to 200 nm and a circularity of 0.85 or more, the large-size inorganic particles being 20 to 70 in number per 100 μm 2 image area of the toner observed with a field-emission scanning electron microscope,

wherein a liberation ratio of the external additive from the toner is less than 35%.

2. The toner of claim 1 , wherein a coverage rate of the mother particles with the inorganic particles having an equivalent circle diameter of 10 nm or more is from 30% to 80%.

3. The toner of claim 1 , wherein the small-size inorganic particles having an equivalent circle diameter of from 30 to 70 nm account for 15% by number or more of the inorganic particles having an equivalent circle diameter of 10 nm or more.

4. The toner of claim 1 , wherein the small-size inorganic particles having an equivalent circle diameter of from 30 to 70 nm account for 35% by number or more of the inorganic particles having an equivalent circle diameter of 10 nm or more.

5. An image forming apparatus, comprising:
an electrostatic latent image bearer;
an electrostatic latent image forming device configured to form an electrostatic latent image on the electrostatic latent image bearer;
a developing device comprising the toner of claim 1 , configured to develop the electrostatic latent image with the toner to form a toner image;
a transfer device configured to transfer the toner image formed on the electrostatic latent image bearer onto a surface of a recording medium; and
a fixing device configured to fix the toner image on the surface of the recording medium.

6. An image forming method, comprising:
forming an electrostatic latent image on an electrostatic latent image bearer;
developing the electrostatic latent image with the toner of claim 1 to form a toner image;
transferring the toner image formed on the electrostatic latent image bearer onto a surface of a recording medium; and
fixing the toner image on the surface of the recording medium.

7. A toner storage unit, comprising:
a container; and
the toner of claim 1 stored in the container.

Assignees

• Suzuki Namie
• Suzuki Kazumi
• Nakajima Hisashi
• Yamauchi Yoshitaka
• Ogino Kohtaroh
• Kaneko Akihiro
• Ricoh Co Ltd

Inventors

• Suzuki Namie
• Suzuki Kazumi
• Nakajima Hisashi
• Yamauchi Yoshitaka
• Ogino Kohtaroh
• Kaneko Akihiro

Classifications

• G03G9/08755

  Polyesters · CPC title

• G03G9/08782

  Waxes · CPC title

• G03G9/08797

  characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature · CPC title

• G03G15/09

  using magnetic brush · CPC title

• G03G15/0806 Primary

  on a donor element, e.g. belt, roller (complete developer unit G03G15/0896) · CPC title