Electrophotographic photoreceptor, image-forming apparatus, and electrophotographic cartridge

1. An electrophotographic photoreceptor comprising a photosensitive layer containing at least one charge transport material represented by the following formula (1) or (2) and a copolymerized polycarbonate resin having repeating units represented by the following formulae (3) and (4):

wherein each of R 1 to R 7 independently represents a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, n represents an integer of 1 to 3, each of k, l, q and r independently represents an integer of 1 to 5, and each of m, o and p independently represents an integer of 1 to 4;

wherein each of R 8 to R 12 independently represents a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, each of s, t and u represents an integer of 1 to 5, and eachof v and w represents an integer of 1 to 4;

wherein Z forms a cyclic saturated aliphatic alkyl group having a carbon number of 5 to 8 including the carbon atom bonded thereto, and the cyclic saturated aliphatic alkyl group has from 1 to 3 methyl groups as the substituent;

wherein each of R 13 to R 16 independently represents a hydrogen atom or a methyl group.

2. The electrophotographic photoreceptor as claimed in claim 1 , wherein said copolymerized polycarbonate resin is represented by the following structural formula (5):

wherein m and n represent a molar ratio, and m:n =from 90:10 to 10:90.

3. The electrophotographic photoreceptor as claimed in claim 1 , wherein the amount of said charge transport material used is from 20 to 70 parts by mass per 100 parts by mass of said copolymerized polycarbonate resin.

4. An image-forming apparatus forming an image by using the electrophotographic photoreceptor claimed in claim 1 , the image-forming apparatus comprising: a charging portion of charging the electrophotographic photoreceptor; an exposure portion of exposing said charged electrophotographic photoreceptor to light to form an electrostatic latent image; a development portion of developing said electrostatic latent image with a toner; a transfer portion of transferring said toner to a receiving object; and a cleaning portion.

5. An electrophotographic cartridge comprising the electrophotographic photoreceptor claimed in claim 1 .

6. The electrophotographic photoreceptor as claimed in claim 1 , wherein the charge transport material represented by formula (1) is present.

7. The electrophotographic photoreceptor as claimed in claim 1 , wherein the charge transport material represented by formula (2) is present.

8. The electrophotographic photoreceptor as claimed in claim 1 , wherein the copolymerization ratio between formula (3) and formula (4) is, in terms of (3):(4), 10:90 to 90:10.

9. The electrophotographic photoreceptor as claimed in claim 1 , wherein the copolymerization ratio between formula (3) and formula (4) is, in terms of (3):(4), 10:90 to 50:50.

10. The electrophotographic photoreceptor as claimed in claim 1 , wherein the copolymerization ratio between formula (3) and formula (4) is, in terms of (3):(4), 15:85 to 40:60.

11. The electrophotographic photoreceptor as claimed in claim 1 , wherein formula (3) is formula (3)-5 or formula (3)-6:

12. The electrophotographic photoreceptor as claimed in claim 1 , wherein formula (4) is formula (4)-1 or formula (4)-4:

13. The electrophotographic photoreceptor as claimed in claim 11 , wherein formula (4) is formula (4)-1 or formula (4)-4:

14. The electrophotographic photoreceptor as claimed in claim 1 , wherein formula (3) is formula (3)-6, and formula (4) is formula (4)-1: