Electrophotographic photoreceptor, and image forming apparatus and process cartridge therefor using the electrophotographic photoreceptor

• US 20070042281A1
• Filed: 08/18/2006
• Published: 02/22/2007
• Est. Priority Date: 08/18/2005
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Yamashita, Yasuyuki, Orito, Takeshi, Toda, Naohiro
• Granted Patent: US 7,960,081 B2
• Time in Patent Office: Days
• US Class Current: 430/59.500
• CPC Class Codes: G03G 5/0696 Phthalocyanines
• CPC Class Codes: G03G 5/142 Inert intermediate layers
• CPC Class Codes: G03G 5/14704 comprising inorganic material
• CPC Class Codes: G03G 5/14786 Macromolecular compounds characterised by specific side-chain substituents or end groups
• CPC Class Codes: G03G 5/14791 Macromolecular compounds characterised by their structure, e.g. block polymers, reticulated polymers, or by their chemical properties, e.g. by molecular weight or acidity

Abstract

An electrophotographic photoreceptor, including an electroconductive substrate; an intermediate layer, located overlying the electroconductive substrate; and a photosensitive layer, located overlying the intermediate layer, wherein the intermediate layer includes a N-alkoxymethylated nylon including a component having a molecular weight not greater than 5,000 in an amount of from 3 to 10% by weight.

Claims

1. An electrophotographic photoreceptor, comprising:

an electroconductive substrate;

an intermediate layer, located overlying the electroconductive substrate; and

a photosensitive layer, located overlying the intermediate layer,

wherein the intermediate layer comprises a N-alkoxymethylated nylon comprising a component having a molecular weight not greater than 5,000 in an amount of from 3 to 10% by weight.

2. The electrophotographic photoreceptor of claim 1, wherein the N-alkoxymethylated nylon comprises a component having a molecular weight not greater than 1,000 in an amount of from 0.3 to 5% by weight.

3. The electrophotographic photoreceptor of claim 1, wherein the N-alkoxymethylated nylon has a conductivity of from 1.5 to 15 μ

S/cm.

4. The electrophotographic photoreceptor of claim 1, wherein the intermediate layer comprises a resin layer comprising the N-alkoxymethylated nylon.

5. The electrophotographic photoreceptor of claim 4, wherein the resin layer comprises:

a first resin layer (antimoire layer) comprising a dispersed filler; and

a second resin layer (charge blocking layer) comprising the N-alkoxymethylated nylon and not containing a dispersed filler.

6. The electrophotographic photoreceptor of claim 5, wherein the antimoire layer overlies the charge blocking layer.

7. The electrophotographic photoreceptor of claim 5, wherein the charge blocking layer has a thickness not greater than 2.0 μ

m.

8. The electrophotographic photoreceptor of claim 1, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer.

9. The electrophotographic photoreceptor of claim 8, wherein the charge generation layer comprises a titanylphthalocyanine as a charge generation material.

10. The electrophotographic photoreceptor of claim 9, wherein the titanylphthalocyanine has a CuKα

1.542 Å

X-ray diffraction spectrum comprising plural diffraction peaks, wherein a maximum diffraction peak is observed at a Bragg (2θ

) angle of 27.2°

;

main peaks are observed at 9.4°

, 9.6° and

24.0°

; and

a minimum diffraction peak is observed at 7.3°

; and

no diffraction peak is observed at an angle greater than 7.3° and

less than 9.4° and

at 26.3°

, wherein said angles may vary by ±

0.2°

, and has an average primary particle diameter not greater than 0.25 μ

m.

11. The electrophotographic photoreceptor of claim 9, wherein at least one of the photosensitive layer or the charge generation layer is formed by a method comprising:

dispersing the titanylphthalocyanine in a solvent until having an average particle size not greater than 0.3 μ

m and a standard deviation thereof not greater than 0.2 μ

m to prepare a dispersion;

filtering the dispersion with a filter having an effective pore size not greater than 3 μ

m to prepare a filtered dispersion; and

coating the filtered dispersion on the intermediate layer.

12. The electrophotographic photoreceptor of claim 9, wherein the titanylphthalocyanine is prepared by a method comprising:

subjecting a titanylphthalocyanine, which is either amorphous or low-crystalline, and which has a maximum diffraction peak having a half width not less than 1°

at a Bragg (2θ

) angle of from 7.0 to 7.5°

±

0.2°

when a specific X-ray of CuKα

having a wavelength of 1.542 Å

irradiates the titanylphthalocyanine and an average primary particle diameter not greater than 0.1 μ

m, to crystal conversion using an organic solvent in the presence of water; and

separating the titanylphthalocyanine from the organic solvent before the titanylphthalocyanine shows crystal growth such that the average primary particle diameter becomes not less than 0.25 μ

m.

13. The electrophotographic photoreceptor of claim 9, wherein the titanylphthalocyanine does not contain a halogenated material.

14. The electrophotographic photoreceptor of claim 12, wherein the amorphous titanylphthalocyanine is prepared by an acid paste method, and wherein the amorphous titanylphthalocyanine is washed with ion-exchanged water until the ion-exchanged water has at least one of a pH of from 6 to 8 or a specific conductivity not greater than 8.

15. The electrophotographic photoreceptor of claim 12, wherein the organic solvent weighs not less than 30 times as much as the amorphous titanylphthalocyanine.

16. The electrophotographic photoreceptor of claim 1, further comprising a protection layer, located overlying the photosensitive layer.

17. The electrophotographic photoreceptor of claim 16, wherein the protection layer comprises an inorganic pigment or a metal oxide having a specific resistivity not less than 10¹⁰ Ω

·

cm.

18. The electrophotographic photoreceptor of claim 17, wherein the metal oxide is at least one member selected from the group consisting of alumina, titanium oxide and silica.

19. The electrophotographic photoreceptor of claim 17, wherein the metal oxide is α

-alumina.

20. The electrophotographic photoreceptor of claim 16, wherein the protection layer further comprises a charge transport polymer material.

21. The electrophotographic photoreceptor of claim 16, wherein the protection layer further comprises a binder resin having a crosslinked structure.

22. The electrophotographic photoreceptor of claim 21, wherein the binder resin has a charge transport site.

23. The electrophotographic photoreceptor of claim 21, wherein the protection layer further comprises a tri- or more functional radical polymerizing monomer having at least one of an acryloyloxy group and a methacryloyloxy group.

24. An image forming apparatus, comprising:

at least one image forming unit comprising;

the electrophotographic photoreceptor according to claim 1;

a charger configured to charge the electrophotographic photoreceptor;

an irradiator configured to irradiate the electrophotographic photoreceptor to form an electrostatic latent image thereon;

an image developer configured to develop the electrostatic latent image with a developer comprising a toner to form a toner image on the electrophotographic photoreceptor; and

a transferer configured to transfer the toner image onto a transfer material.

25. The image forming apparatus of claim 24, further comprising a plurality of the image forming units.

26. The image forming apparatus of claim 24, further comprising a process cartridge including:

the electrophotographic photoreceptor according to claim 1;

and

at least one of the charger, the irradiator, the image developer and a cleaner configured to clean the surface of the electrophotographic photoreceptor,

wherein the process cartridge is detachable from the image forming apparatus.