Electrophotographic photoconductor, and process cartridge and electrophotographic apparatus using the same

• US 20030059695A1
• Filed: 06/21/2002
• Published: 03/27/2003
• Est. Priority Date: 06/21/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Tanaka, Kawori, Suzuki, Yasuo, Sasaki, Masaomi, Kawamura, Shinichi, Tamoto, Nozomu, Nagai, Kazukiyo, Li, Hongguo
• Granted Patent: US 6,939,651 B2
• Time in Patent Office: Days
• US Class Current: 430/66
• CPC Class Codes: G03G 5/0546 Polymers comprising at least one carboxyl radical, e.g. polyacrylic acid, polycrotonic acid, polymaleic acid; Derivatives thereof, e.g. their esters, salts, anhydrides, nitriles, amides
• CPC Class Codes: G03G 5/0578 Polycondensates comprising silicon atoms in the main chain
• CPC Class Codes: G03G 5/0596 Macromolecular compounds characterised by their physical properties
• CPC Class Codes: G03G 5/075 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds G03G5/078 takes precedence

Abstract

An electrophotographic photoconductor comprising at least an electroconductive support and a photoconductive layer which is formed on said electroconductive support, the outermost layer of the photoconductor contains particles comprising a polyorganosiloxane-containing phase which contains polyorganosiloxane and an organic polymer-containing phase which contains organic polymer without silicon and has a polyorganosiloxane content which is less than the polyorganosiloxane-containing phase, each phase being exposed at the top surface of the photoconductor.

Claims

1. An electrophotographic photoconductor comprising:

an electroconductive support and a photoconductive layer thereon; and

an outermost layer of the photoconductive layer comprising particles;

wherein a surface of the particles comprises;

a) a polyorganosiloxane-containing phase which contains polyorganosiloxane; and

b) an organic polymer-containing phase which contains organic polymer without silicone or having polyorganosiloxane content less than the polyorganosiloxane-containing phase.

2. An electrophotographic photoconductor according to claim 1, wherein a ratio of the polyorganosiloxane to the organic polymer (mass ratio of the polyorganosiloxane/organic polymer) is in a range of 30:

70 to 90;

10.

3. An electrophotographic photoconductor according to claim 1, wherein the particles have a cross sectional shape of circle or oval and are dispersed in the outermost surface layer of the photoconductive layer.

4. An electrophotographic photoconductor according to claim 1, wherein the organic polymer comprises one of:

1) a copolymer of a (meth) acrylic acid ester; and

2) a copolymer of a mixture of a monomer copolymerizable with the (meth) acrylic acid ester and the (meth) acrylic acid ester.

5. The electrophotographic photoconductor according to claim 1, wherein the photoconductive layer comprises an inorganic filler.

6. The electrophotographic photoconductor according to claim 1, wherein the photoconductive layer comprises a high molecular charge transport material.

7. The electrophotographic photoconductor according to claim 1, wherein the high molecular charge transport material comprises a unit represented by the following formula (A) and a unit represented by the following formula (B), in which the compositional ratio (k) of the unit represented by the formula (A) and the compositional ratio (j) of the unit represented by the formula (B) satisfy 0<

k/(k+j)≦

1;

8. The electrophotographic photoconductor according to claim 1, wherein a high molecular charge transport material comprises a unit represented by the following formula (C) and a unit represented by the following formula (B), in which the compositional ratio (k) of the unit represented by the formula (C) and the compositional ratio (j) of the unit represented by the formula (B) satisfy 0<

k/(k+j)≦

1;

9. An electrophotographic photoconductor comprising:

an electroconductive support and a photoconductive layer thereon;

wherein an outermost layer of the photoconductor comprises an organically modified polyorganosiloxane graft copolymer comprising;

a) a main chain of a polyorganosiloxane; and

b) a graft chain of an organic polymer without containing silicon.

10. The electrophotographic photoconductor according to claim 9, wherein an acryl-modified polyorganosiloxane is prepared by emulsion graft copolymerizing of a polyorganosiloxane compound represented by the following formula (I) and a (meth)acrylic acid ester represented by the following formula (II) or a mixture of the (meth) acrylic acid ester and a monomer copolymerizable with the (meth)acrylic acid ester via emulsion graft copolymerization;

11. The electrophotographic photoconductor according to claim 10, wherein the acryl-modified polyorganosiloxane is cleaned with alcohol.

12. The electrophotographic photoconductor according to claim 10, wherein a sodium content to the acryl-modified polyorganosiloxane in the outermost surface layer of the photoconductive layer is 500 ppm or less.

13. The electrophotographic photoconductor according to claim 10, wherein a content of sulfur containing ion to the acryl-modified polyorganosiloxane in the outermost surface layer of the photoconductive layer is 800 ppm or less.

14. The electrophotographic photoconductor according to claim 10, wherein the acryl-modified polyorganosiloxane is dispersed as a particle phase and the average particle diameter of the acryl-modified polyorganosiloxane particles (volume average particle diameter(D50)) is in the range of 0.1 to 0.6 μ

m.

15. The electrophotographic photoconductor according to claim 10, wherein the acryl-modified polyorganosiloxane is subjected to a high pressure with at least one of a solvent and a binder and crushed and dispersed by liquid impact under elevated pressure, so as to be dispersed as a particle phase and the average particle diameter of the acryl-modified polyorganosiloxane particles (volume average particle diameter(D₅₀)) is in the range of 0.1 to 0.6 μ

m.

16. The electrophotographic photoconductor according to claim 9, wherein the photoconductive layer comprises an inorganic filler.

17. The electrophotographic photoconductor according to claim 9, wherein the photoconductive layer comprises a high molecular charge transport material.

18. The electrophotographic photoconductor according to claim 9, wherein the high molecular charge transport material comprises a unit represented by the following formula (A) and a unit represented by the following formula (B), in which the compositional ratio (k) of the unit represented by the formula (A) and the compositional ratio (j) of the unit represented by the formula (B) satisfy 0<

k/(k+j)≦

1;

19. The electrophotographic photoconductor according to claim 9, wherein a high molecular charge transport material comprises a unit represented by the following formula (C) and a unit represented by the following formula (B), in which the compositional ratio (k) of the unit represented by the formula (C) and the compositional ratio (j) of the unit represented by the formula (B) satisfy 0<

k/(k+j)≦

1;

20. A process cartridge comprising an electrophotographic photoconductor which comprises:

an electroconductive support and a photoconductive layer thereon; and

an outermost layer of the photoconductive layer comprising particles;

wherein a surface of the particles comprises;

a) a polyorganosiloxane-containing phase which contains polyorganosiloxane; and

b) an organic polymer-containing phase which contains organic polymer without silicone or having polyorganosiloxane content less than the polyorganosiloxane-containing phase.

21. An electrophotographic device comprising:

an electrophotographic photoconductor;

a charging unit configured to charge a latent image carrier;

a light irradiating unit configured to irradiate light imagewisely onto the latent image carrier so as to form a latent electrostatic image theron;

an image developing unit configured to develop the latent electrostatic image to a developed image; and

a transferring unit configured to transfer the developed image to a recording medium;

wherein the electrophotographic photoconductor comprises;

an electroconductive support and a photoconductive layer thereon; and

an outermost layer of the photoconductive layer comprising particles;

wherein a surface of the particles comprises;

a) a polyorganosiloxane-containing phase which contains polyorganosiloxane; and

b) an organic polymer-containing phase which contains organic polymer without silicone or having polyorganosiloxane content less than the polyorganosiloxane-containing phase.

22. A process cartridge comprising an electrophotographic photoconductor which comprises:

an electroconductive support and a photoconductive layer thereon;

an outermost layer of the photoconductive layer comprising particles;

wherein a surface of the particles comprises;

a) a polyorganosiloxane-containing phase which contains polyorganosiloxane; and

b) an organic polymer-containing phase which contains organic polymer without silicone or having polyorganosiloxane content less than the polyorganosiloxane-containing phase.

23. An electrophotographic device comprising:

an electrophotographic photoconductor;

a charging unit configured to charge a latent image carrier;

a light irradiating unit configured to irradiate light imagewisely onto the latent image carrier so as to form a latent electrostatic image theron;

an image developing unit configured to develop the latent electrostatic image to a developed image; and

a transferring unit configured to transfer the developed image to a recording medium;

wherein the electrophotographic photoconductor comprises;

an electroconductive support; and

a photoconductive layer formed on the electroconductive support;

wherein an outermost layer of the photoconductor comprises an organically modified polyorganosiloxane graft copolymer comprising;

a) a main chain of a polyorganosiloxane; and

b) a graft chain of an organic polymer without containing silicon.