ELECTROPHOTOGRAPHIC PHOTORECEPTORS HAVING REDUCED TORQUE AND IMPROVED MECHANICAL ROBUSTNESS

• US 20080166643A1
• Filed: 12/13/2006
• Published: 07/10/2008
• Est. Priority Date: 11/01/2006
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Gagnon, Yvan, Bender, Timothy P., Hu, Nan-Xing, De Jong, Kathy L., Gardner, Sandra J., Graham, John F., Markovics, James M., Hsiao, Cheng-Kuo
• Granted Patent: US 7,851,113 B2
• Time in Patent Office: Days
• US Class Current: 430/66
• CPC Class Codes: G03G 2215/00957 Compositions
• CPC Class Codes: G03G 5/14704 comprising inorganic material
• CPC Class Codes: G03G 5/14726 Halogenated polymers
• CPC Class Codes: G03G 5/14773 Polycondensates comprising silicon atoms in the main chain
• 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
• CPC Class Codes: G03G 5/14795 Macromolecular compounds characterised by their physical properties

Abstract

Overcoat layers, which may be useful for reducing torque in electrophotographic photoreceptors, are provided. The overcoat layers include a polymer matrix having a particulate inorganic lubricant and a particulate fluoropolymer uniformly dispersed therein. Also provided are electrophotographic photoreceptors that include a substrate and the overcoat layers, electrophotographic imaging apparatuses that include such photoreceptors, and methods for forming the photoreceptors.

Claims

1. An overcoat layer for electrophotographic imaging members, comprising:

a polymer matrix;

a particulate inorganic lubricant; and

a particulate fluoropolymer;

wherein the particulate inorganic lubricant and the particulate fluoropolymer are uniformly dispersed throughout the matrix.

2. The overcoat layer according to claim 1, wherein said particulate inorganic lubricant is selected from the group consisting of boron nitride, graphite, fluorinated graphite, oxidized graphite, molybdenum sulfide, and mixtures thereof.

3. The overcoat layer according to claim 1, wherein said particulate fluoropolymer is selected from the group consisting of poly(tetrafluoroethylene) (PTFE), poly(vinylidene fluoride), poly(vinylidene fluoride co-hexafluoropropylene), and mixtures thereof.

4. The overcoat layer according to claim 1, wherein said particulate inorganic lubricant comprises plurality of particles ranging in size of from about 0.05 to about 5 μ

m, and said particulate fluoropolymer comprises a plurality of particles ranging in size of from about 0.05 to about 5 μ

m.

5. The overcoat layer according to claim 1, wherein said particulate inorganic lubricant comprises a plurality of boron nitride particles ranging in size of from about 0.05 to about 5 μ

m, and said particulate fluoropolymer comprises a plurality of poly(tetrafluoroethylene) particles ranging in size of from about 0.05 to about 5 μ

m.

6. The overcoat layer according to claim 1, wherein said particulate inorganic lubricant is present at from about 0.5 to about 10% by weight, relative to a total weight of the overcoat layer, and said particulate fluoropolymer is present at from about 1 to about 20% by weight, relative to a total weight of the overcoat layer.

7. The overcoat layer according to claim 1, further comprising a charge-transport component.

8. The overcoat layer according to claim 7, wherein said charge-transport component is present at from about 25 to about 60% by weight, relative to a total weight of the overcoat layer.

9. The overcoat layer according to claim 1, wherein said polymer matrix comprises a polymer selected from the group consisting of polycarbonates, aromatic polyesters, polyurethanes, polyimides, and mixtures thereof.

10. The overcoat layer according to claim 1, wherein said polymer matrix comprises a cross-linked polymer selected from the group consisting of melamine-formaldehyde resins, phenol-formaldehyde resins, melamine-phenol-formaldehyde resins, polysiloxanes, and mixtures thereof.

11. The overcoat layer according to claim 1, wherein polymer matrix comprises a cross-linked polysiloxane, wherein the cross-linked polysiloxane is produced by hydrolysis and condensation of a coating formulation that comprises an aromatic silicon-containing compound of Formula (I) and a silicon-containing hole-transport compound of Formula (II):

A-[-L-SiR_nX_3-n]_m  

 

(I)

B-[-L-SiR_nX_3-n]_m  

 

(II)

wherein A is a multiple-valent organic group;

B is a hole-transport moiety;

L is a divalent linkage;

R is a hydrocarbon group selected from the group consisting of alkyl groups, arylalkyl groups, aryl groups, and alkylaryl groups;

X is a hydrolytic group;

m is an integer from 1 to 6;

n is an integer from 0 to 2; and

the m, n, L, R, and X of Formulas (I) and (II) are independently selected.

12. The overcoat layer according to claim 11, wherein, in each of Formulas (I) and (II):

L is an independently selected divalent linkage selected from the group consisting of;

13. The overcoat layer according to claim 11, wherein the aromatic silicon-containing compound of Formula (I) is selected from the group consisting of compounds of Formulas (I-A), (I-B) and (I-C):

14. The overcoat layer according to claim 11, wherein the silicon-containing hole-transport compound of Formula (II) is selected from the group consisting of compounds of Formulas (II-A) through (II-N):

15. An electrophotographic imaging member comprising:

a substrate,

a charge-generating layer,

a charge-transporting layer, and

an overcoat layer;

wherein said overcoat layer comprises;

a polymer matrix;

a particulate inorganic lubricant; and

a particulate fluoropolymer;

wherein the particulate inorganic lubricant and the particulate fluoropolymer are uniformly dispersed throughout the matrix.

16. The electrophotographic imaging member according to claim 15, wherein said particulate inorganic lubricant is selected from the group consisting of boron nitride, graphite, fluorinated graphite, oxidized graphite, molybdenum sulfide, and mixtures thereof.

17. The electrophotographic imaging member according to claim 15, wherein said particulate fluoropolymer is selected from the group consisting of poly(tetrafluoroethylene) (PTFE), poly(vinylidene fluoride), poly(vinylidene fluoride co-hexafluoropropylene), and mixtures thereof.

18. The electrophotographic imaging member according to claim 15, wherein said particulate inorganic lubricant comprises plurality of particles ranging in size of from about 0.05 to about 5 μ

m, and wherein said particulate fluoropolymer comprises a plurality of particles ranging in size of from about 0.05 to about 5 μ

m.

19. The electrophotographic imaging member according to claim 15, wherein said particulate inorganic lubricant comprises a plurality of boron nitride particles ranging in size of from about 0.05 to about 5 μ

m, and said particulate fluoropolymer comprises a plurality of poly(tetrafluoroethylene) particles ranging in size of from about 0.05 to about 5 μ

m.

20. The electrophotographic imaging member according to claim 15, wherein said particulate inorganic lubricant is present at from about 0.5 to about 10% by weight, relative to a total weight of the overcoat layer, and said particulate fluoropolymer is present at from about 1 to about 20% by weight, relative to a total weight of the overcoat layer.

21. The electrophotographic imaging member according to claim 15, wherein said overcoat layer further comprises a charge-transport component.

22. The electrophotographic imaging member according to claim 21, wherein said charge-transport component is present at from about 25 to about 60% by weight, relative to a total weight of the overcoat layer.

23. The electrophotographic imaging member according to claim 15, wherein said polymer matrix comprises a polymer selected from the group consisting of polycarbonates, aromatic polyesters, polyurethanes, polyimides, and mixtures thereof.

24. The electrophotographic imaging member according to claim 15, wherein said polymer matrix comprises a cross-linked polymer selected from the group consisting of melamine-formaldehyde resins, phenol-formaldehyde resins, melamine-phenol-formaldehyde resins, polysiloxanes, and mixtures thereof.

25. The electrophotographic imaging member according to claim 15, wherein polymer matrix comprises a cross-linked polysiloxane, wherein the cross-linked polysiloxane is produced by hydrolysis and condensation of a coating formulation that comprises an aromatic silicon-containing compound of Formula (I) and a silicon-containing hole-transport compound of Formula (II):

A-[-L-SiR_nX_3-n]_m  

 

(I)

B-[-L-SiR_nX_3-n]_m  

 

(II)

wherein A is a multiple-valent organic group;

B is a hole-transport moiety;

L is a divalent linkage;

R is a hydrocarbon group selected from the group consisting of alkyl groups, arylalkyl groups, aryl groups, and alkylaryl groups;

X is a hydrolytic group;

m is an integer from 1 to 6;

n is an integer from 0 to 2; and

the m, n, L, R, and X of Formulas (I) and (II) are independently selected.

26. The electrophotographic imaging member according to claim 25, wherein, in each of Formulas (I) and (II):

L is an independently selected divalent linkage selected from the group consisting of;

27. The electrophotographic imaging member according to claim 25, wherein the aromatic silicon-containing compound of Formula (I) is selected from the group consisting of compounds of Formulas (I-A), (I-B) and (I-C):

28. The electrophotographic imaging member according to claim 25, wherein the silicon-containing hole-transport compound of Formula (II) is selected from the group consisting of compounds of Formulas (II-A) through (II-N):

29. An electrophotographic imaging apparatus comprising:

a charging unit;

a cleaning unit; and

an electrophotographic imaging member;

wherein said electrophotographic imaging member comprises;

a substrate;

an optional hole-blocking layer;

a charge-generating layer comprising a photosensitive pigment;

a charge-transporting layer comprising a polycarbonate polymer binder and at least one charge-transport material; and

an overcoat layer;

wherein said overcoat layer comprises;

a polymer matrix;

a particulate inorganic lubricant; and

a particulate fluoropolymer;

wherein the particulate inorganic lubricant and the particulate fluoropolymer are uniformly dispersed throughout the matrix.

30. The electrophotographic imaging apparatus according to claim 29, wherein said charging unit comprises an AC bias charging roil that contacts and charges the electrophotographic imaging member.