Process cartridge

Patent metadata

Field	Value
Publication number	US-12529971-B2
Application number	US-202217936104-A
Country	US
Kind code	B2
Filing date	Sep 28, 2022
Priority date	Oct 8, 2021
Publication date	Jan 20, 2026
Grant date	Jan 20, 2026

Abstract

Provided is a process cartridge that is excellent in initial charge rising performance, and in charge uniformity of a halftone image throughout a long period of time from the start of use until after endurance. Specifically, provided is a process cartridge including: an electrophotographic photosensitive member; a toner; and a developing unit, wherein the toner contains toner particles and an external additive A, the external additive A, and wherein the electrophotographic photosensitive member includes an electroconductive support, a photosensitive layer, and a surface protective layer, wherein the surface protective layer contains electroconductive particles.

First claim

What is claimed is:

1 . A process cartridge that is detachable from a main body of an electrophotographic image forming apparatus, the process cartridge comprising:
an electrophotographic photosensitive member; a toner; and a developing unit; the electrophotographic photosensitive member comprising an electroconductive support, a photosensitive layer formed on the electroconductive support, and a surface protective layer formed on the surface of the electrophotographic photosensitive member; the surface protective layer containing electroconductive titanium oxide particles each containing a niobium atom; the developing unit being configured to accommodate the toner, and to supply the toner to a surface of the electrophotographic photosensitive member; and the toner comprising toner particles and an external additive A, external additive A having (i) a long diameter of 100 to 3,000 nm, (ii) an aspect ratio of 5.0 or more, and (iii) a specific resistance of 1×10 5 to 1×10 8 Ω·cm or less, wherein a ratio of a number of the toner particle having the external additive A on surface thereof to a number of the toner particle is 30 number % or more when observed by using a scanning electron microscope, in each of the electroconductive titanium oxide particles, a concentration ratio calculated as niobium atom concentration/titanium atom concentration at an inside portion at 5% of a maximum diameter of a measurement particle from a surface of the particle is 2.0 or more times as high as a concentration ratio calculated as niobium atom concentration/titanium atom concentration at a central portion of the particle, a content of the electroconductive titanium oxide particles in the surface protective layer is 5 to 70 vol %, and the surface protective layer has a volume resistivity of 1.0×10 9 to 1.0×10 14 Ω·cm.

2 . The process cartridge according to claim 1 , wherein the external additive A is titanium oxide particles.

3 . The process cartridge according to claim 1 , wherein the external additive A is rutile-type titanium oxide particles.

4 . The process cartridge according to claim 1 , wherein the toner particles each contain boric acid.

5 . The process cartridge according to claim 1 , wherein the electroconductive titanium oxide particles each contain 2.6 to 10.0 mass % niobium .

6 . The process cartridge according to claim 5 , wherein a ratio of the electroconductive titanium oxide particles in the surface protective layer is 40 to 70 vol %, and
the volume resistivity of the surface protective layer is 1.0×10 10 to 1.0×10 14 Ω·cm.

7 . The process cartridge according to claim 1 , wherein the external additive A has a long diameter of 500 to 2,000 nm.

8 . The process cartridge according to claim 1 , wherein the surface protective layer has a volume resistivity of 1.0×10 9 to 7.2×10 13 Ω·cm.

9 . An electrophotographic image forming apparatus, comprising:
an electrophotographic photosensitive member; a toner; and a developing unit; the electrophotographic photosensitive member comprising an electroconductive support, a photosensitive layer formed on the electroconductive support, and a surface protective layer formed on the surface of the electrophotographic photosensitive member; the protective layer comprises electroconductive titanium oxide particles each containing a niobium atom; the developing unit being configured to accommodate the toner, and to supply the toner to a surface of the electrophotographic photosensitive member; and the toner contains toner particles and an external additive A, external additive A having (i) a long diameter of 100 to 3,000 nm, (ii) an aspect ratio of 5.0 or more, and (iii) a specific resistance of 1×10 5 to 1×10 8 Ω·cm, wherein a ratio of a number of the toner particle having the external additive A on surface thereof to a number of the toner particle is 30 number % or more when observed by using a scanning electron microscope, in each of the electroconductive titanium oxide particles, a concentration ratio calculated as niobium atom concentration/titanium atom concentration at an inside portion at 5% of a maximum diameter of a measurement particle from a surface of the particle is 2.0 or more times as high as a concentration ratio calculated as niobium atom concentration/titanium atom concentration at a central portion of the particle, a content of the electroconductive particles in the surface protective layer is 5 to 70 vol %, and the surface protective layer has a volume resistivity of 1.0×10 9 to 1.0×10 14 Ω·cm.

10 . The electrophotographic image forming apparatus according to claim 9 , wherein the external additive A is titanium oxide particles.

11 . The electrophotographic image forming apparatus according to claim 9 , wherein the external additive A is rutile-type titanium oxide particles.

12 . The electrophotographic image forming apparatus according to claim 9 , wherein the toner particles each contain boric acid.

13 . The electrophotographic image forming apparatus according to claim 9 , wherein the electroconductive titanium oxide particles each contain 2.6 to 10.0 mass % niobium.

14 . The electrophotographic image forming apparatus according to claim 13 , wherein a ratio of the electroconductive particles in the surface protective layer is 40 to 70 vol %, and the volume resistivity of the surface protective layer is 1.0×10 10 to 1.0×10 14 Ω·cm.

15 . The electrophotographic image forming apparatus according to claim 9 , wherein the external additive A has a long diameter of 500 to 2,000 nm.

16 . The electrophotographic image forming apparatus according to claim 9 , wherein the surface protective layer has a volume resistivity of 1.0×10 9 to 7.2×10 13 Ω·cm.

Assignees

• Canon Kk

Inventors

• Saeki Tatsuya
• Kenmoku Takashi
• Uratani Kozue
• Inoue Koki
• Sekido Kunihiko

Classifications

• G03G9/0819

  characterised by the dimensions of the particles · CPC title

• G03G9/0823

  Electric parameters · CPC title

• G03G9/09708 Primary

  Inorganic compounds · CPC title

• G03G2215/00957

  Compositions · CPC title

• G03G5/14795

  Macromolecular compounds characterised by their physical properties · CPC title