Photoreceptor, method for preparing photoreceptor, and image forming apparatus and process cartridge using the photoreceptor

1. A photoreceptor comprising:

an electroconductive substrate;

a photosensitive layer located overlying the electroconductive substrate; and

a protective layer located overlying the photosensitive layer, wherein the protective layer includes a crosslinked resin, which is crosslinked by irradiation with ultraviolet rays and which is formed by crosslinking a coating liquid, wherein the coating liquid comprises:

(I) a radically polymerizable compound having a charge transport structure;

(II) a compound having a residual group of a polycarboxylic acid compound and a group having the following formula (10):

wherein each of R5 and R6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms; and

(III) at least one of a compound having the below-mentioned formula (2) and a compound having the below-mentioned formula (3):

wherein each of R 7 and R 8 independently represents a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and Z 1 represents a vinylene group, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a 2,5-thiophenediyl group, and

wherein each of Ar 1 and Ar 2 independently represents an aromatic group having 6 to 14 carbon atoms, Z 2 represents a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, and each of R 9 and R 10 independently represents a hydrogen atom, or a methyl group,

wherein the at least one of the compound having formula (2) and the compound having formula (3) is included in the composition in an amount of from not less than 0.5% to 3% by weight based on a weight of the radically polymerizable compound having a charge transport structure.

2. The photoreceptor according to claim 1 , wherein a group of the crosslinked resin has the following formula (11):

wherein each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and each of m and n is independently an integer of from 1 to 5.

3. The photoreceptor according to claim 2 , wherein the crosslinked resin is obtained by crosslinking a composition including:

a radically polymerizable compound having a charge transport structure;

a compound having the following formula (1):

wherein each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and each of m and n is independently an integer of from 1 to 5; and

at least one of the compound having formula (2), and the compound having formula (3).

4. The photoreceptor according to claim 3 , wherein each of m and n in formula (1) is independently 1 or 2, and wherein a total of m and n is from 2 or 3.

5. The photoreceptor according to claim 3 , wherein the composition further includes a tri- or more-functional radically polymerizable compound having no charge transport structure.

6. The photoreceptor according to claim 3 , wherein the radically polymerizable compound having a charge transport structure is a monofunctional radically polymerizable compound.

7. The photoreceptor according to claim 1 , wherein the protective layer further includes a filler.

8. The photoreceptor according to claim 7 , wherein the filler is an inorganic filler.

9. The photoreceptor according to claim 8 , wherein the inorganic filler includes at least one selected from the group consisting of silicon oxide fillers, titanium oxide fillers, and aluminum oxide fillers.

10. An image forming apparatus comprising:

the photoreceptor according to claim 1 ;

a charger to subject a surface of the photoreceptor to corona charging;

an irradiator to irradiate the charged photoreceptor with light to form an electrostatic latent image on the surface of the photoreceptor;

a developing device to develop the electrostatic latent image using a toner to form a toner image on the surface of the photoreceptor; and

a transferring device to transfer the toner image onto a recording medium.

11. A process cartridge comprising:

at least the photoreceptor according to claim 1 ; and

a charger to subject the photoreceptor to corona charging,

wherein the process cartridge is detachably attachable to an image forming apparatus as a single unit.

12. A method for preparing the photoreceptor according to claim 1 , comprising:

forming the photosensitive layer overlying the electroconductive substrate;

applying a coating liquid including a protective layer composition overlying the photosensitive layer, wherein the protective layer composition comprises:

(I) a radically polymerizable compound having a charge transport structure;

(II) a compound having formula (1); and

(III) at least one of a compound having formula (2) or a compound having formula (3); and

irradiating the applied coating liquid with ultraviolet rays to crosslink the protective layer composition to form the protective layer.

13. A photoreceptor comprising:

an electroconductive substrate;

a photosensitive layer located overlying the electroconductive substrate; and

a protective layer located overlying the photosensitive layer, wherein the protective layer includes a crosslinked resin, which is crosslinked by irradiation with ultraviolet rays and which is formed by crosslinking a coating liquid, wherein the coating liquid comprises:

(I) a radically polymerizable compound having a charge transport structure;

(II) a compound having a residual group of a polycarboxylic acid compound and a group having the following formula (10):

wherein each of R5 and R6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms; and

(III) at least one of a compound having the below-mentioned formula (2) and a compound having the below-mentioned formula (3):

wherein each of R 7 and R 8 independently represents a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and Z 1 represents a vinylene group or a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, and

wherein each of Ar 1 and Ar 2 independently represents an aromatic group having 6 to 14 carbon atoms, Z 2 represents a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, and each of R 9 and R 10 independently represents a hydrogen atom, or a methyl group.

14. The photoreceptor according to claim 13 , wherein the coating liquid comprises at least one compound of formula (2) selected from the group consisting of:

15. The photoreceptor according to claim 13 , wherein the coating liquid comprises at least one compound of formula (3) selected from the group consisting of:

16. A method for preparing a photoreceptor, comprising:

forming a photosensitive layer overlying an electroconductive substrate;

applying a coating liquid including a protective layer composition overlying the photosensitive layer; and

irradiating the applied coating liquid with ultraviolet rays to crosslink the protective layer composition,

wherein the protective layer composition includes:

(I) a radically polymerizable compound having a charge transport structure;

(II) a compound having the following formula (1):

wherein each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and each of m and n is independently an integer of from 1 to 5; and

(III) at least one of a compound having the following formula (2):

wherein each of R 7 and R 8 independently represents a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and Z 1 represents a vinylene group or a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms; and

a compound having the following formula (3):

wherein each of Ar 1 and Ar 2 independently represents an aromatic group having 6 to 14 carbon atoms, Z 2 represents a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, and each of R 9 and R 10 independently represents a hydrogen atom, or a methyl group.