Coating liquid and electrophotographic photoreceptor prepared using the coating liquid

• US 20060134540A1
• Filed: 12/16/2005
• Published: 06/22/2006
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Niimi, Tatsuya, Orito, Takeshi, Toda, Naohiro, Ohta, Katsuichi, Tamoto, Nozomu, Kondo, Maiko
• Granted Patent: US 7,824,830 B2
• Time in Patent Office: Days
• US Class Current: 430/59.500
• CPC Class Codes: C08G 69/50 with aldehydes

Abstract

A coating liquid including an N-alkoxymethylated nylon and a solvent, wherein the N-alkoxymethylated nylon includes one or more ions in an amount of from 200 to 500 ppm based on a weight of the N-alkoxymethylated nylon or one or more alkylamines in an amount of from 15 to 100 ppm based on a weight of the N-alkoxymethylated nylon. A photoreceptor including an electroconductive substrate; a charge blocking layer located overlying the substrate; a moiré preventing layer located overlying the charge blocking layer; and a photosensitive layer located overlying the moiré preventing layer, wherein the charge blocking layer is formed using the coating liquid.

Claims

1. A coating liquid comprising an N-alkoxymethylated nylon and a solvent, wherein the N-alkoxymethylated nylon includes one or more ions in an amount of from 200 to 500 ppm based on a weight of the N-alkoxymethylated nylon.

3. A photoreceptor comprising:

an electroconductive substrate;

a charge blocking layer located overlying the substrate;

a moiré

preventing layer located overlying the charge blocking layer; and

a photosensitive layer located overlying the moiré

preventing layer,

wherein the charge blocking layer is formed by a method comprising;

coating the coating liquid according to claim 1 overlying the substrate; and

drying the coated liquid to form the charge blocking layer.

4. The photoreceptor according to claim 3, wherein the charge blocking layer has a thickness of not less than 0.1 μ

m and less than 2.0 μ

m.

5. The photoreceptor according to claim 3, wherein the moiré

preventing layer comprises a binder resin and an inorganic pigment, wherein a volume ratio of the inorganic pigment to the binder resin is from 1/1 to 3/1.

6. The photoreceptor according to claim 5, wherein the binder resin comprises a thermally crosslinked resin.

7. The photoreceptor according to claim 5, wherein the inorganic pigment comprises titanium oxide.

8. The photoreceptor according to claim 3, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer, and wherein the charge generation layer comprises a titanyl phthalocyanine.

9. The photoreceptor according to claim 8, wherein the titanyl phthalocyanine is a titanyl phthalocyanine crystal having an average primary particle diameter not greater than 0.25 μ

m and an X-ray diffraction spectrum such that a maximum peak is observed at a Bragg (2 θ

) angle of 27.2°

±

0.2°

;

a peak is observed at each of Bragg (2 θ

) angles of 9.4°

±

0.2°

, 9.6±

0.2° and

24.0±

0.2°

;

a lowest angle peak is observed at an angle of 7.3°

±

0.2°

;

no peak is observed between the lowest angle peak and the 9.4°

peak; and

no peak is observed at a Bragg (2 θ

) angle of 26.3±

0.2°

, when a Cu—

Kα

X-ray having a wavelength of 1.542 Å

is used.

10. The photoreceptor according to claim 8, wherein the charge generation layer is prepared using a coating liquid prepared by a method comprising:

dispersing the titanyl phthalocyanine crystal in a solvent such that the titanyl phthalocyanine crystal therein has a particle diameter distribution such that an average particle diameter is not greater than 0.3 μ

m and a standard deviation is not greater than 0.2 μ

m to prepare a dispersion; and

filtering the dispersion using a filter having an effective pore diameter of not greater than 3 μ

m.

11. The photoreceptor according to claim 8, wherein the titanyl phthalocyanine crystal is prepared by a method comprising:

providing a titanyl phthalocyanine pigment having an amorphous state or a low crystallinity, which has an average particle diameter not greater than 0.1 μ

m and has a second X-ray diffraction spectrum such that a maximum peak having a half width not less than 1°

is observed at a Bragg (2 θ

) angle of from 7.0°

to 7.5°

with a tolerance of ±

0.2°

;

changing the crystal form of the titanyl phthalocyanine having an amorphous state or a low crystallinity in an organic solvent in the presence of water so that the resultant titanyl phthalocyanine crystal has an X-ray diffraction spectrum such that a maximum peak is observed at a Bragg (2 θ

) angle of 27.2°

±

0.2°

;

a peak is observed at each of Bragg (2 θ

) angles of 9.4°

±

0.2°

, 9.6±

0.2° and

24.0±

0.2°

;

a lowest angle peak is observed at an angle of 7.3°

±

0.2°

;

no peak is observed between the lowest angle peak and the 9.4°

peak; and

no peak is observed at a Bragg (2 θ

) angle of 26.3°

±

0.2°

, when a Cu—

K α

X-ray having a wavelength of 1.542 Å

is used; and

filtering the dispersion including the titanyl phthalocyanine crystal before the average primary particle diameter thereof exceeds 0.25 μ

m, to prepare the titanyl phthalocyanine crystal.

12. The photoreceptor according to claim 11, wherein the titanyl phthalocyanine having an amorphous state or a low crystallinity is prepared by an acid paste method, and then washed using ion-exchanged water to an extent such that the ion-exchange water used for washing has a pH of from 6 to 8 and/or a specific conductivity not greater than 8 μ

S/cm after the washing.

13. The photoreceptor according to claim 11, wherein an amount of the organic solvent is not less than 30 times that of the titanyl phthalocyanine having an amorphous state or a low crystallinity.

14. The photoreceptor according to claim 8, wherein the titanyl phthalocyanine crystal is synthesized using raw materials including no halogen atom.

15. The photoreceptor according to claim 3, further comprising a protective layer located overlying the photosensitive layer.

16. The photoreceptor according to claim 15, wherein the protective layer comprises an inorganic pigment having a resistivity not less than 10¹⁰ Ω

·

cm.

17. The photoreceptor according to claim 15, wherein the protective layer comprises a crosslinked resin.

18. The photoreceptor according to claim 17, wherein the crosslinked resin is prepared by reacting and crosslinking a radical polymerizable polyfunctional monomer having three or more functional groups and no charge transport structure and a radical polymerizable monofunctional monomer having a charge transport structure.

2. A coating liquid comprising an N-alkoxymethylated nylon, wherein the N-alkoxymethylated nylon includes one or more alkylamines in an amount of from 15 to 100 ppm based on a weight of the N-alkoxymethylated nylon.

19. A photoreceptor comprising:

an electroconductive substrate;

a charge blocking layer located overlying the substrate;

a moiré

preventing layer located overlying the charge blocking layer; and

a photosensitive layer located overlying the moiré

preventing layer,

wherein the charge blocking layer is formed by a method comprising;

coating the coating liquid according to claim 2 overlying the substrate; and

drying the coated liquid to form the charge blocking layer.

20. The photoreceptor according to claim 19, wherein the one or more alkylamines include a primary alkylamine.

21. The photoreceptor according to claim 19, wherein the charge blocking layer has a thickness of not less than 0.1 μ

m and less than 2.0 μ

m.

22. The photoreceptor according to claim 19, wherein the moiré

preventing layer comprises a binder resin and an inorganic pigment, wherein a volume ratio of the inorganic pigment to the binder resin is from 1/1 to 3/1.

23. The photoreceptor according to claim 22, wherein the binder resin comprises a thermally crosslinked resin.

24. The photoreceptor according to claim 22, wherein the inorganic pigment comprises titanium oxide.

25. The photoreceptor according to claim 19, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer, and wherein the charge generation layer comprises a titanyl phthalocyanine.

26. The photoreceptor according to claim 25, wherein the titanyl phthalocyanine is a titanyl phthalocyanine crystal having an average primary particle diameter of not greater than 0.25 μ

m and an X-ray diffraction spectrum such that a maximum peak is observed at a Bragg (2 θ

) angle of 27.2°

±

0.2°

;

a peak is observed at each of Bragg (2 θ

) angles of 9.4°

±

0.2°

, 9.6±

0.2° and

24.0±

0.2°

;

a lowest angle peak is observed at an angle of 7.3°

±

0.2°

;

no peak is observed between the lowest angle peak and the 9.4°

peak; and

no peak is observed at a Bragg (2 θ

) angle of 26.30 ±

0.2°

, when a Cu—

Kα

X-ray having a wavelength of 1.542 Å

is used.

27. The photoreceptor according to claim 25, wherein the charge generation layer is prepared using a coating liquid prepared by a method comprising:

dispersing the titanyl phthalocyanine crystal in a solvent such that the titanyl phthalocyanine crystal therein has a particle diameter distribution such that an average particle diameter is not greater than 0.3 μ

m and a standard deviation is not greater than 0.2 μ

m to prepare a dispersion; and

filtering the dispersion using a filter having an effective pore diameter not greater than 3 μ

m.

28. The photoreceptor according to claim 25, wherein the titanyl phthalocyanine crystal is prepared by a method comprising:

providing a titanyl phthalocyanine pigment having an amorphous state or a low crystallinity, which has an average particle diameter not greater than 0.1 μ

m and has a second X-ray diffraction spectrum such that a maximum peak having a half width not less than 1°

is observed at a Bragg (2 θ

) angle of from 7.0°

to 7.5°

with a tolerance of ±

0.2°

;

changing the crystal form of the titanyl phthalocyanine having an amorphous state or a low crystallinity in an organic solvent in the presence of water so that the resultant titanyl phthalocyanine crystal has an X-ray diffraction spectrum such that a maximum peak is observed at a Bragg (2 θ

) angle of 27.2°

±

0.2°

;

a peak is observed at each of Bragg (2 θ

) angles of 9.4°

±

0.2°

, 9.6±

0.2° and

24.0±

0.2°

;

a lowest angle peak is observed at an angle of 7.3°

±

0.2°

;

no peak is observed between the lowest angle peak and the 9.4°

peak; and

no peak is observed at a Bragg (2 θ

) angle of 26.3°

±

0.2°

, when a Cu—

Kα

X-ray having a wavelength of 1.542 Å

is used; and

filtering the dispersion including the titanyl phthalocyanine crystal before the average primary particle diameter thereof exceeds 0.25 μ

m, to prepare the titanyl phthalocyanine crystal.

29. The photoreceptor according to claim 28, wherein the titanyl phthalocyanine having an amorphous state or a low crystallinity is prepared by an acid paste method, and then washed using ion-exchanged water to an extent such that the ion-exchange water used for washing have a pH of from 6 to 8 and/or a specific conductivity not greater than 8 μ

S/cm after the washing.

30. The photoreceptor according to claim 28, wherein an amount of the organic solvent is not less than 30 times that of the titanyl phthalocyanine having an amorphous state or a low crystallinity.

31. The photoreceptor according to claim 25, wherein the titanyl phthalocyanine crystal is synthesized using raw materials including no halogen atom.

32. The photoreceptor according to claim 19, further comprising a protective layer located overlying the photosensitive layer.

33. The photoreceptor according to claim 32, wherein the protective layer comprises an inorganic pigment having a resistivity not less than 10¹⁰ Ω

·

cm.

34. The photoreceptor according to claim 32, wherein the protective layer comprises a crosslinked resin.

35. The photoreceptor according to claim 34, wherein the crosslinked resin is prepared by reacting and crosslinking a radical polymerizable polyfunctional monomer having three or more functional groups and no charge transport structure and a radical polymerizable monofunctional monomer having a charge transport structure.