Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, image forming apparatus, and polyarylate resin

1. An electrophotographic photoreceptor, comprising:

a conductive support; and

at least a photosensitive layer on the conductive support,

wherein the photosensitive layer comprises a polyarylate resin and the polyarylate resin has a repeating structure represented by formula (1), a repeating structure represented by formula (3)′, and a repeating structure represented by formula (4)′,

wherein the polyarylate resin contains the repeating structure represented by formula (3)′ in an amount of 0.2% to 1%, based on the total amount of the repeating structures represented by formula (2)′ and formula (3)′, which are each partial structures of formula (1), and

wherein the polyarylate resin contains the repeating structure represented by formula (4)′ in an amount of 15 ppm or less, based on a total amount of the repeating structures represented by formula (2)′, formula (3)′, and formula (4)′:

wherein formula (1):

each Y independently represents at least one divalent group selected from the group consisting of an m-phenylene group, a p-phenylene group, and a divalent group configured of two p-phenylene groups bonded to each other by an oxygen atom;

n indicates the number of repetitions;

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other, and

wherein in formula (2)′, formula (3)′, and formula (4)′:

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other.

2. The electrophotographic photoreceptor according to claim 1 , wherein the amount of the repeating structure represented by formula (3)′ is 0.3% to 0.8%, based on the total amount of repeating structures represented by formula (2)′ and formula (3)′.

3. The electrophotographic photoreceptor according to claim 1 , wherein the amount of the repeating structure represented by formula (3)′ is 0.4% to 0.8%, based on the total amount of the repeating structures represented by formula (2)′ and formula (3)′.

4. An electrophotographic photoreceptor, comprising:

a conductive support; and

at least a photosensitive layer on the conductive support, wherein the photosensitive layer comprises a polyarylate resin and the polyarylate resin has a repeating structure represented by formula (1), a repeating structure represented by formula (3)′, and a repeating structure represented by formula (4)′,

wherein the polyarylate resin contains the repeating structure represented by formula (4)′ in an amount of 10 ppm or less, based on the total amount of the repeating structures represented by formula (2)′, formula (3)′, and formula (4)′:

wherein in formula (1):

each Y independently represents at least one divalent group selected from the group consisting of an m-phenylene group, a p-phenylene group, and a divalent group configured of two p-phenylene groups bonded to each other by an oxygen atom;

n indicates the number of repetitions;

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other, and

wherein in formula (2)′, formula (3)′, and formula (4)′:

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other.

5. The electrophotographic photoreceptor according to claim 1 , wherein the photosensitive layer is a laminate of a charge transport layer and a charge generation layer.

6. The electrophotographic photoreceptor according to claim 5 , wherein the charge transport layer comprises at least one charge transport substance selected from the compounds represented by the following formulae (CT-1) to (CT-3):

7. The electrophotographic photoreceptor according to claim 5 , wherein the charge generation layer comprises hydroxygallium phthalocyanine, the hydroxygallium phthalocyanine being hydroxygallium phthalocyanine crystals which, in analysis by X-ray diffractometry using a CuKα line, has an intense diffraction peak at a Bragg angle (2θ±0.2) of 28.3°.

8. The electrophotographic photoreceptor according to claim 7 , wherein the hydroxygallium phthalocyanine is synthesized using a non-halogen solvent.

9. The electrophotographic photoreceptor according to claim 7 , wherein the hydroxygallium phthalocyanine pigment isolated from the charge generation layer has an α-chloronaphthalene content of 0.1 ng/cm 2 or less.

10. An image forming apparatus, comprising the electrophotographic photoreceptor according to claim 1 .

11. The image forming apparatus according to claim 10 , wherein in an electrophotographic process, a toner developed on the photoreceptor is directly transferred to a printing medium without via an intermediate transfer body.

12. A cartridge comprising the electrophotographic photoreceptor according to claim 1 .

13. A polyarylate resin having repeating structures represented by the formula (1), formula (3)′, and formula (4)′, and containing the repeating structure represented by the formula (4)′ in an amount of 10 ppm or less based on the total amount of the repeating structures represented by formula (2)′, formula (3)′, and formula (4)′, which are each partial structures of formula (1):

wherein in formula (1):

each Y independently represents at least one divalent group selected from the group consisting of an m-phenylene group, a p-phenylene group, and a divalent group configured of two p-phenylene groups bonded to each other by an oxygen atom;

n indicates the number of repetitions;

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other, and

wherein in formula (2)′, formula (3)′, and formula (4)′:

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other.

14. The polyarylate resin according to claim 13 , wherein the repeating structure represented by formula (3)′ is a repeating structure represented by formula (3a)′:

wherein in formula (3a)′:

each X independently represents a single bond, —CR 1 R 2 —, O, CO, or S; and

R 1 and R 2 each independently represent a hydrogen atom, a methyl group, or an ethyl group, or R 1 and R 2 represent a cyclohexylidene group formed by the R 1 and R 2 bonded to each other.