Multilayer electrophotographic photoconductor and image-forming apparatus

1. An electrophotographic photoconductor comprising:

an electrically conductive base; and

a photosensitive layer disposed on the electrically conductive base,

wherein the photosensitive layer has

a structure 1) in which a charge-generation layer including at least a charge-generating material and a charge-transport layer including at least a charge-transporting material and a binder resin are stacked in that order, or

a structure 2) in which at least the charge-generating material, the charge-transporting material, and the binder resin are included in the same layer; and

wherein the binder resin is a terpolymer polycarbonate resin represented by general formula (I) shown below:

wherein, in general formula (I),

k+m+n=1 and 0.4≦k+m≦0.8;

W 1 represents —O— or —CO—;

W 2 represents a single bond;

R 1 represents a hydrogen atom or a methyl group;

R 2 to R 8 and R a each independently represents a hydrogen atom;

K represents 0; and

X represents a cycloalkylidene group.

2. The electrophotographic photoconductor according to claim 1 , wherein the charge-transporting material includes, as a hole-transporting material, a compound represented by general formula (II) or (III) shown below:

wherein, in general formula (II),

R 9 to R 15 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group;

two adjacent groups selected from R 11 to R 15 may bind to each other to form a ring; and

a represents an integer of 0 to 5, and

wherein, in general formula (III),

R 16 to R 23 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group;

b represents an integer of 0 to 5;

c represents an integer of 0 to 4; and

d represents 0 or 1.

3. The electrophotographic photoconductor according to claim 1 , wherein the content of the charge-transporting material is in the range of about 30 parts by mass to about 50 parts by mass relative to 100 parts by mass of the binder resin.

4. The electrophotographic photoconductor according to claim 1 , wherein the charge-transport layer has a thickness of about 5 to about 50 μm.

5. The electrophotographic photoconductor according to claim 1 , wherein the photosensitive layer having a structure in which at least the charge-generating material, the charge-transporting material, and the binder resin are included in the same layer has a thickness of about 10 to about 50 μm.

6. The electrophotographic photoconductor according to claim 1 , wherein the charge-generating material is X-form metal-free phthalocyanine or titanyl phthalocyanine.

7. An image-forming apparatus having an image-bearing member comprising the electrophotographic photoconductor according to claim 1 , the image-forming apparatus comprising:

the image-bearing member;

a charging portion operable for charging the surface of the image-bearing member;

an exposing portion operable for exposing the surface of the image-bearing member and forming an electrostatic latent image;

a developing portion operable for developing the electrostatic latent image to form a toner image; and

a transferring portion operable for transferring the toner image from the image-bearing member to a recording member,

wherein the charging portion is of contact charging type.

8. An image-forming apparatus comprising:

an image-bearing member;

a charging portion operable for charging the surface of the image-bearing member;

an exposing portion operable for exposing the surface of the image-bearing member and forming an electrostatic latent image;

a developing portion operable for developing the electrostatic latent image to form a toner image; and

a transferring portion operable for transferring the toner image from the image-bearing member to a recording media,

wherein the image-bearing member comprises the electrophotographic photoconductor according to claim 1 .

9. The image-forming apparatus according to claim 8 , wherein the charge-transporting material includes, as a hole-transporting material, a compound represented by general formula (II) or (III) shown below:

wherein, in general formula (II),

R 9 to R 15 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group;

two adjacent groups selected from R 11 to R 15 may bind to each other to form a ring; and

a represents an integer of 0 to 5, and

wherein, in general formula (III),

R 16 to R 23 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group;

b represents an integer of 0 to 5;

c represents an integer of 0 to 4; and

d represents 0 or 1.

10. The image-forming apparatus according to claim 8 , wherein the content of the charge-transporting material is about 30 to about 50 parts by mass relative to 100 parts by mass of the binder resin.

11. The image-forming apparatus according to claim 8 , wherein the charge-transport layer has a thickness of about 5 to about 50 μm.

12. The image-forming apparatus according to claim 8 , wherein the photosensitive layer having a structure in which at least the charge-generating material, the charge-transporting material, and the binder resin are included in the same layer has a thickness of about 10 to about 50 μm.

13. The image-forming apparatus according to claim 8 , wherein the charge-generating material is X-form metal-free phthalocyanine or titanyl phthalocyanine.

14. The image-forming apparatus according to claim 8 , wherein the charging portion is of contact charging type.

15. The image-forming apparatus according to claim 14 , wherein the charging portion is a charging roller of contact charging type.

16. The image-forming apparatus according to claim 15 , wherein in the charging portion, a DC voltage only is applied to the charging roller.