Carrier, two-component developer, supplemental developer, image forming method, process cartridge and image forming apparatus

Patent metadata

Field	Value
Publication number	US-9519234-B2
Application number	US-201314410711-A
Country	US
Kind code	B2
Filing date	Jun 26, 2013
Priority date	Jun 27, 2012
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

There is provided a carrier including magnetic core particles; and a coating layer on a surface of each of the magnetic core particles, wherein the coating layer contains electroconductive particles; wherein the electroconductive particles are electroconductive particles in which white inorganic pigments are coated with phosphorus-doped tin or tungsten-doped tin; and wherein a dope ratio of phosphorus or tungsten to tin in the phosphorus-doped tin or tungsten-doped tin is 0.010 to 0.100.

First claim

The invention claimed is:

1. A carrier comprising:
magnetic core particles; and
a coating layer on a surface of each of the magnetic core particles,
wherein the coating layer comprises electroconductive particles,
wherein the electroconductive particles are electroconductive particles in which a white inorganic pigment is coated with phosphorus-doped tin or tungsten-doped tin,
wherein a dope ratio of phosphorus or tungsten to tin in the phosphorus-doped tin or the tungsten-doped tin is 0.010 to 0.100, and
wherein a particle diameter of the white inorganic pigment in the electroconductive particles R1 (μm) and a particle diameter of the electroconductive particles R2 (μm) satisfy the following expression: 1.4≦R2/R1≦2.6.

2. The carrier according to claim 1 , wherein the white inorganic pigment is aluminum oxide, titanium dioxide, or barium sulfate.

3. The carrier according to claim 1 , wherein a powder specific resistivity of the electroconductive particles is 3 Ω·cm to 20 Ω·cm.

4. The carrier according to claim 1 , wherein a volume average particle diameter of the electroconductive particles is 0.35 μm to 0.65 μm.

5. The carrier according to claim 1 , wherein a volume average particle diameter of the carrier is 32 μm to 40 μm.

6. The carrier according to claim 1 , wherein a volume resistivity of the carrier is 8 Log Ω·cm to 14 Log Ω·cm.

7. A two-component developer comprising:
the carrier according to claim 1 ; and
a toner.

8. The two-component developer according to claim 7 , wherein the toner is a color-toner.

9. A supplemental developer comprising:
a carrier; and
a toner,
wherein 2 parts by mass to 50 parts by mass of the toner is contained relative to 1 part by mass of the carrier, and
wherein the carrier is the carrier according to claim 1 .

10. A process cartridge comprising:
a developer being the two-component developer according to claim 7 ;
an electrostatic latent image bearing member; and
a developing unit configured to develop with a developer an electrostatic latent image formed on the electrostatic latent image bearing member to thereby form a visible image.

11. An image forming method comprising:
forming an electrostatic latent image on an electrostatic latent image bearing member;
developing the electrostatic latent image with a developer to thereby form a visible image;
transferring the visible image to a recording medium; and
fixing the visible image transferred to the recording medium,
wherein the developer is the two-component developer according to claim 7 .

12. A process cartridge comprising:
a developer being the supplemental developer according to claim 9 ;
an electrostatic latent image bearing member; and
a developing unit configured to develop with a developer an electrostatic latent image formed on the electrostatic latent image bearing member to thereby form a visible image.

13. An image forming method comprising:
forming an electrostatic latent image on an electrostatic latent image bearing member;
developing the electrostatic latent image with a developer to thereby form a visible image;
transferring the visible image to a recording medium; and
fixing the visible image transferred to the recording medium,
wherein the developer is the supplemental developer according to claim 9 .

Assignees

• Kishida Hiroyuki
• Yaguchi Shigenori
• Tohmatsu Hiroshi
• Sakata Koichi
• Iwatsuki Hitoshi
• Tano Toyoaki
• Ricoh Co Ltd

Inventors

• Kishida Hiroyuki
• Yaguchi Shigenori
• Tohmatsu Hiroshi
• Sakata Koichi
• Iwatsuki Hitoshi
• Tano Toyoaki

Classifications

• G03G9/1075

  Structural characteristics of the carrier particles, e.g. shape or crystallographic structure · CPC title

• G03G21/18 Primary

  using a processing cartridge {, whereby the process cartridge comprises at least two image processing means in a single unit} · CPC title

• H01F1/01

  of inorganic materials (H01F1/44 takes precedence) · CPC title

• G03G9/1139 Primary

  Inorganic components of coatings · CPC title

• G03G9/0839 Primary

  Treatment of the magnetic components; Combination of the magnetic components with non-magnetic materials (G03G9/0834 takes precedence) · CPC title