Imaging members

• US 20050136349A1
• Filed: 12/23/2003
• Published: 06/23/2005
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Yu, Robert C.U., Mishra, Satchidanand, Horgan, Anthony M., Ahuja, Suresh K., Murti, Dasarao K.
• Granted Patent: US 7,166,397 B2
• Time in Patent Office: Days
• US Class Current: 430/58.50
• CPC Class Codes: G03G 5/0525 Coating methods
• CPC Class Codes: G03G 5/0528 Macromolecular bonding materials
• CPC Class Codes: Y10S 430/103 Radiation sensitive composition or product containing specified antioxidant

Abstract

An electrophotographic imaging member having a charge generating layer and a charge transport layer overlayed thereon is provided. The charge transport layer has a lower surface and an upper surface, wherein the lower surface is in contiguous contact with the charge generating layer. The charge transport layer comprises a film forming polymer binder and a charge transport compound molecularly dispersed or dissolved therein to form a solid solution. The concentration of the charge transport compound in the charge transport layer decreases from the lower surface to the upper surface. In such a construction, the resulting charge transport layer exhibits enhanced cracking suppression, improved wear resistance, excellent imaging member electrical performance, and improved copy print out quality.

Claims

1. An imaging member comprising:

an optional supporting substrate;

a charge generating layer; and

,

a charge transport layer deposited on the charge generating layer, wherein the charge transport layer comprises a lower surface in contact with the charge generating layer and an upper surface, and wherein the charge transport layer comprises a film forming polymer binder and a charge transport compound dispersed therein, wherein the concentration of the charge transport compound in the charge transport layer decreases from the lower surface to the upper surface.

2. The imaging member of claim 1, wherein the concentration of the charge transport compound in the upper surface is about 10% to about 90% less than the concentration of the charge transport compound in the lower surface.

3. The imaging member of claim 1, wherein the concentration of the charge transport compound in the upper surface is about 20% to about 80% less than the concentration of the charge transport compound in the lower surface.

4. The imaging member of claim 1, wherein the concentration of the charge transport compound in the upper surface is about 30% to about 70% less than the concentration of the charge transport compound in the lower surface.

5. The imaging member of claim 1, wherein the concentration of the charge transport compound in the upper surface is about 40% to about 60% less than the concentration of the charge transport compound in the lower surface.

6. The imaging member of claim 1, wherein the charge transport layer further comprises a stabilizing hindered phenol and wherein the concentration of the hindered phenol increases from the lower surface to the upper surface of the charge transport layer.

7. The imaging member of claim 1, wherein the charge transport compound progressively decreases in concentration from the lower surface to the upper surface of the charge transport layer.

8. The imaging member of claim 1, wherein the charge transport compound is molecularly dispersed in the film forming polymer to form a solid solution.

9. The imaging member of claim 1, wherein the lower surface comprises from about 50 to about 90 weight percent of charge transport compound based on the total weight of the lower surface region and the upper surface comprises from about 5 to about 10 weight percent of the charge transport compound based on the total weight of the upper surface region.

10. The imaging member of claim 9, wherein the amount of charge transport compound in the lower surface region comprises from about 40 to about 80 weight percent based on the total weight of the region.

11. The imaging member of claim 9, wherein the amount of charge transport compound in the upper surface region comprises from about 2 to about 8 weight percent based on the total weight of the region.

12. The imaging member of claim 1, wherein the charge transport compound is an aryl amine.

13. The imaging member of claim 12, wherein the aryl amine is of the formula

14. The imaging member of claim 1, wherein the charge transport compound is selected from the group consisting of triphenylmethane, bis(4-diethylamine-2-methylphenyl) phenylmethane, stylbene, hydrozone, tritolylamine;

arylamine;

enamine phenanthrene diamine;

N,N′

-bis-(3,4-dimethylphenyl)-4-biphenyl amine;

N,N′

,bis-(4-methylphenyl)-N,N′

-bis(4-ethylphenyl)-1,1′

-3,3′

-dimethylbiphenyl)-4,4′

diamine;

4-4′

-bis(diethylamino)-2,2′

-dimethylriphenylethane;

N,N′

-diphenyl-N,N′

-bis(3-methylphenyl)-[1,1′

-biphenyl]-,4′

diamine;

N,N′

-diphenyl-N,N′

-bis(4-methylphenyl)-1,1′

-biphenyl-4,4′

diamine;

N,N′

-diphenyl-N,N′

-bis (alkylphenyl)-1,1′

-biphenyl-4,4-diamine; and

, N,N′

-diphenyl-N,N′

-bis(chlorophenyl)-1,1′

-biphenyl-4,4′

-diamine.

15. The imaging member of claim 13, wherein the charge transport compound is selected from the group consisting of N,N′

-diphenyl-N,N′

-bis (3-methylphenyl)-[1,1′

-biphenyl]-4,4′

diamine or N,N′

-diphenyl-N,N′

-bis(4-methylphenyl)-1,1′

-biphenyl-4,4′

diamine.

16. The imaging member of claim 1, wherein the charge transport compound is a terphenyl diamine.

17. The imaging member of claim 16, wherein the terphenyl diamine is of the formula

18. The imaging member of claim 17, wherein the terphyl diamine is selected from the group consisting of N,N′

-bis(4-methylphenyl)-N,N′

-bis[4-(1-butyl)-phenyl]-[p-terphenyl]-4,4″

-diamine, N,N′

-bis(3-methylphenyl)-N,N′

-bis[4-(1-butyl)-phenyl]-[p-terphenyl]-4,4″

-diamine, N,N′

-bis(4-t-butylphenyl)-N,N′

-bis[4-(1-butyl)-phenyl]-[p-terphenyl]-4,4″

-diamine, N,N′

,N″

,N′

″

-tetra[4-(1-butyl)-phenyl]-p-terphenyl]-4,4″

-diamine, and N,N′

,N″

, N′

″

-tetra[4-t-butyl-phenyl]-[p-terphenyl]-4,4″

-diamine.

19. The imaging member of claim 1, wherein the binder is selected from the group consisting of polyesters, polyvinyl butyrals, polycarbonates, polystyrene, and polyvinyl formats.

20. The imaging member of claim 19, wherein the binder is a polycarbonate having a weight average molecular weight of from about 20,000 to about 100,000.

21. The imaging member of claim 19, wherein the polycarbonate is selected from the group consisting of poly(4,4′

-isopropylidene diphenyl carbonate), poly(4,4′

-diphenyl-1,1′

-cyclohexane carbonate), or a polymer blend of both.

22. The imaging member of claim 1, wherein the total thickness of the layers of the charge transport layer is from about 10 micrometers to about 110 micrometers.

23. The imaging member of claim 1, wherein the upper surface of the charge transport layer further comprises a nano particle dispersion wherein the particles are selected from the group consisting of silica, metal oxides, wax, polyethylene, and PTFE particles.

24. An imaging member comprising:

an optional supporting substrate;

a photogenerating layer; and

,

a charge transport layer deposited on the charge generating layer, wherein the charge transport layer comprises a first charge transport layer comprised of a charge transport component and a film forming polymer binder, and thereover and in contact with the first charge transport layer, a plurality of additional charge transport layers, each comprised of a charge transport component and a film forming polymer binder, wherein the amount of charge transport component in said layers of the charge transport layer is the greatest in said first charge transport layer and progressively decreases to the upper layer of the additional charge transport layers.

25. An imaging member in accordance with claim 24, wherein said first charge transport layer contains from about 50 to about 90 weight percent of a charge transport component.

26. An imaging member in accordance with claim 24, wherein said first charge transport layer contains from about 60 to about 70 weight percent of a charge transport component.

27. An imaging member in accordance with claim 24, wherein said plurality of additional charge transport layers is from about 2 to about 15 layers.

28. An imaging member in accordance with claim 24, wherein said plurality of additional charge transport layers is from about 2 to about 7 layers.

29. An imaging member in accordance with claim 24, wherein said plurality of additional charge transport layers is from about 2 to about 3 layers.

30. An imaging member in accordance with claim 24, wherein the upper layer of the additional charge transport layers contain from about 10 to about 30 weight percent of said charge transport components.

31. An imaging member in accordance with claim 29, wherein the upper layer of the additional charge transport layers contain from about 5 to about 25 weight percent of said charge transport components.

32. An imaging member in accordance with claim 29, wherein the base layer of the additional charge transport layers contains from about 40 to about 60 weight percent of said charge transport components.

33. An imaging member in accordance with claim 29, wherein the base layer of the additional charge transport layers contains from about 30 to about 50 weight percent of said charge transport components.

34. An imaging member in accordance with claim 29, wherein the second layer of the additional charge transport layers contains from about 25 to about 45 weight percent of said charge transport components.

35. An imaging member in accordance with claim 29, wherein the third layer of the additional charge transport layers contains from about 20 to about 40 percent of said charge transport components.

36. An imaging member in accordance with claim 29, wherein the fourth layer of the additional charge transport layers contains from about 15 to about 35 percent of said charge transport components.

37. An imaging member in accordance with claim 24, wherein said plurality of additional charge transport layers represent 3 layers and wherein the base layer of the additional charge transport layers contains from about 40 to about 60 weight percent of said charge transport components, the second layer of the additional charge transport layers contains from about 30 to about 50 weight percent of said charge transport components, and the third layer of the additional charge transport layers contains from about 10 to about 30 weight percent by weight of said charge transport components and wherein said first charge transport layer contains from about 50 to about 90 weight percent of said charge transport components.

38. An imaging member in accordance with claim 24, wherein said plurality of additional charge transport layers represent 3 layers and wherein the base layer of the additional charge transport layers contains from about 30 to about 50 weight percent of said charge transport components, the second layer of the additional charge transport layers contains from about 10 to about 35 weight percent of said charge transport components, and the third layer of the additional charge transport layers contains from about 5 to about 25 weight percent by weight of said charge transport components and wherein said first charge transport layer contains from about 40 to about 80 weight percent of said charge transport components.

39. An imaging member in accordance with claim 24, wherein each of the layers of the multiple charge transport layer is of a thickness of from about 5 to about 10 micrometers.

40. An imaging member in accordance with claim 24, wherein each of the layers of the multiple charge transport layer is of the same thickness.

41. An imaging member in accordance with claim 24, wherein each of the layers of the multiple charge transport layer is of different thickness.

42. An imaging member in accordance with claim 24, wherein each of said charge transport layers contain N,N′

-diphenyl-N,N′

-bis(3-methylphenyl)-[1,1′

-biphenyl]-4,4′

diamine.

43. An imaging member in accordance with claim 24, wherein each of said charge transport layers contain N,N′

-diphenyl-N,N′

-bis(4-methylphenyl)-[1,1′

-biphenyl]-4,4′

diamine.

44. An imaging member in accordance with claim 24, further comprising an adhesive layer and an overcoat layer.

45. An imaging member in accordance with claim 24, further comprising a substrate with a thickness of from about 50 micrometers to about 300 micrometers.

46. An imaging member in accordance with claim 24, wherein said substrate has a thickness of from about 80 to about 120 micrometers.

47. An imaging member in accordance with claim 24, further comprising a hole blocking layer of gamma amino silane, zinc oxide, titanium oxide, silica, polyvinyl butyral, and phenolic resins.

48. An imaging member in accordance with claim 47, wherein said hole blocking layer has a thickness of from 0.2 micrometers to about 2 micrometers.

49. An imaging member in accordance with claim 24, wherein said charge generating layer comprises metal free phthalocyanines, metal phthalocyanines, vandyl phthalocyanines, perylenes, titanyl phthalocyanines, hydroxy gallium phthalocyanines, selenium, selenium alloys, or mixtures thereof.

50. The imaging member of claim 24, wherein the charge transport layer further comprises a stabilizing hindered phenol and wherein the concentration of the hindered phenol increases from the first charge transport layer to the layer of the additional charge transport layers.

51. The imaging member of claim 24, wherein the upper layer of the additional charge transport layers further comprises a nano particle dispersion wherein the particles are selected from the group consisting of silica, metal oxides, waxy polyethylene, and PTFE particles.

52. An imaging member comprising:

an optional supporting substrate;

a photogenerating layer; and

a charge transport layer, wherein the charge transport layer comprises;

a first charge transport layer deposited on the charge generating layer comprised of a charge transport component molecularly dispersed in a film forming polymer resin binder, and thereover and in contact with the first charge transport layer;

a plurality of additional charge transport layers comprised of a charge transport component and a resin binder and wherein the amount of charge transport component in said layers is the greatest in said first charge transport layer and the least in the upper layer of the additional charge transport layers, and wherein the multiple charge transport layer further contains a hindered phenol in said additional charge transport layers, wherein the amount of said hindered phenol is the least in the layer of the additional charge transport layers in contact with said first charge transport layer and the greatest in said upper layer of the additional charge transport layers.

53. An imaging member comprising:

a supporting substrate;

an optional electrically conductive layer;

an optional hole blocking layer;

a photogenerating layer; and

,

a first charge transport layer in contact with said photogenerating layer and wherein said first charge transport layer is comprised of a charge transport component molecularly dispersed in a film forming polymer resin binder, and thereover and in contact with said first charge transport layer, a plurality of additional charge transport layers, each comprised of a charge transport component and a hinder phenol molecularly dispersed in a resin binder, and wherein the amount of charge transport component in said layers decreases in sequence from the first charge transport layer to the upper layer of the additional charge transport layers; and

wherein the amount of hinder phenol increases in sequence from the first charge transport layer to the upper layer of the additional charge transport layers.