Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that can satisfactorily form a photosensitive layer, and is excellent in fogging resistance.SOLUTION: An electrophotographic photoreceptor includes a conductive substrate, and one or more photosensitive layers including a first photosensitive layer. The first photosensitive layer contains a charge generator, a binder resin, a specific electron transport agent, and a hole transport agent. The binder resin includes polyarylate resin. The polyarylate resin has repeating units (1), (2), (3), and (4).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Electrophotographic photoreceptors are used as image carriers in electrophotographic image forming apparatuses (e.g., printers or multifunction machines). Electrophotographic photoreceptors include a photosensitive layer. As electrophotographic photoreceptors, for example, single-layer electrophotographic photoreceptors and multi-layer electrophotographic photoreceptors are used. The single-layer electrophotographic photoreceptor includes a single photosensitive layer having a charge generation function and a charge transport function. The multi-layer electrophotographic photoreceptor includes a photosensitive layer including a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

[0003] Patent Document 1 describes an electrophotographic photoreceptor having a surface layer containing a polyarylate resin obtained from a divalent carboxylic acid component and a dihydric phenol component, as shown in the following formula.

[0004] [ka] [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-20514 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the present inventors have found through their studies that the electrophotographic photoreceptor described in Patent Document 1 is insufficient in terms of increasing the solubility of the binder resin in a solvent to form a good photosensitive layer, and further, the present inventors have found through their studies that the electrophotographic photoreceptor described in Patent Document 1 is also insufficient in terms of fogging resistance.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor capable of forming a good photosensitive layer and having excellent fogging resistance. Another object of the present invention is to provide a process cartridge and an image forming apparatus capable of forming an image with less fogging. [Means for solving the problem]

[0008] The electrophotographic photoreceptor of the present invention comprises a conductive substrate and at least one photosensitive layer. The at least one photosensitive layer includes a first photosensitive layer. The first photosensitive layer is provided on the outermost side of the at least one photosensitive layer. The first photosensitive layer contains a charge generating agent, a binder resin, an electron transport agent, and a hole transport agent. The binder resin contains a polyarylate resin. The polyarylate resin has repeating units represented by formulas (1), (2), (3), and (4). A third content, which is the content of the repeating unit represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3), is greater than 0% and less than 50%. A fourth content, which is the content of the repeating unit represented by formula (4) relative to the total number of repeating units represented by formulas (2) and (4), is 35% or more and less than 70%. The electron transport agent includes a compound represented by formula (11), (12), (13), (14), (15), (16), or (17).

[0009] [ka]

[0010] In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1). 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2).

[0011] [ka]

[0012] In the formulae (X1) and (X2), * represents a bond.

[0013] [ka]

[0014] Q in the formula (11) 1 and Q 2 , Q in the formula (12) 21 , Q 22 , Q 23 , and Q 24 , Q in the formula (13) 31 and Q 32 , Q in the formula (14) 41 , Q 42 , and Q 43 , Q in the formula (15) 51 , Q 52 , Q 53 , and Q 54 , Q in the formula (16) 61 and Q 62 and Q in the formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 each independently represents an oxygen atom or a sulfur atom.

[0015] The process cartridge of the present invention includes at least one selected from the group consisting of a charging device, an exposure device, a developing device, and a transfer device, and the above-mentioned electrophotographic photoreceptor.

[0016] The image forming apparatus of the present invention includes an image carrier, a charging device that charges the surface of the image carrier to a positive polarity, an exposure device that exposes the charged surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier, a developing device that supplies toner to the surface of the image carrier to develop the electrostatic latent image into a toner image, and a transfer device that transfers the toner image from the image carrier to a transferee. The image carrier is the electrophotographic photoreceptor described above. Effect of the Invention

[0017] The electrophotographic photoreceptor of the present invention can form a good photosensitive layer and has excellent fogging resistance. The process cartridge and image forming apparatus of the present invention can form an image with little fogging. [Brief description of the drawings]

[0018] [Figure 1] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Diagram 2] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Diagram 3] 1 is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Figure 4] 1 is a partial cross-sectional view of a positively charged multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Diagram 5] 1 is a partial cross-sectional view of a positively charged multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Figure 6] 1 is a partial cross-sectional view of a positively charged multi-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to a first embodiment of the present invention. [Figure 7] FIG. 11 is a diagram illustrating an example of an image forming apparatus according to a second embodiment of the present invention. [Figure 8] 1 is a 1H-NMR spectrum of polyarylate resin (R-1). [Figure 9]FIG. 2 is a diagram illustrating an example of the configuration of a scratching device. [Figure 10] 10 is a cross-sectional view taken along line XX in FIG. 9. [Figure 11] 10 is a side view of the fixing base, scratching needle, and electrophotographic photosensitive member shown in FIG. 9. [Figure 12] FIG. 2 shows scratches formed on the surface of a photosensitive layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be practiced by making appropriate modifications within the scope of the object of the present invention. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. In addition, when the compound name is followed by "system" to represent the name of a polymer, it means that the repeating unit of the polymer is derived from the compound or its derivative. In addition, "general formula" and "chemical formula" are collectively described as "formula". In the explanation of the formula, "independently" means that it may represent the same group or different groups. Each component described in this specification may be used alone or in combination of two or more types, unless otherwise specified.

[0020] First, the substituents used in this specification will be described. Examples of halogen atoms (halogen groups) include fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodo groups).

[0021] Unless otherwise specified, the alkyl groups having 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 5 carbon atoms, 1 to 4 carbon atoms, and 1 to 3 carbon atoms are each linear or branched and unsubstituted. Examples of the alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 2-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2 ... Examples of alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 5 carbon atoms, alkyl groups having 1 to 4 carbon atoms, and alkyl groups having 1 to 3 carbon atoms are the groups having the corresponding number of carbon atoms among the groups mentioned as examples of alkyl groups having 1 to 8 carbon atoms.

[0022] Perfluoroalkyl groups having 1 to 10 carbon atoms, perfluoroalkyl groups having 3 to 10 carbon atoms, perfluoroalkyl groups having 5 to 7 carbon atoms, and perfluoroalkyl groups having 6 carbon atoms are linear or branched and unsubstituted, unless otherwise specified. Examples of perfluoroalkyl groups having 1 to 10 carbon atoms include trifluoromethyl, perfluoroethyl, perfluoro-n-propyl, perfluoroisopropyl, perfluoro-n-butyl, perfluoro-sec-butyl, perfluoro-tert-butyl, perfluoro-n-pentyl, perfluoro-1-methylbutyl, perfluoro-2-methylbutyl, perfluoro-3-methylbutyl, perfluoro-1-ethylpropyl, perfluoro-2-ethylpropyl, perfluoro-1,1-dimethylpropyl, perfluoro-1,2-dimethylpropyl, perfluoro-2,2-dimethylpropyl, perfluoro-n-hexyl, perfluoro-1-methylpentyl, perfluoro-2-methylpent ... Examples of perfluoroalkyl groups include fluoro-3-methylpentyl, perfluoro-4-methylpentyl, perfluoro-1,1-dimethylbutyl, perfluoro-1,2-dimethylbutyl, perfluoro-1,3-dimethylbutyl, perfluoro-2,2-dimethylbutyl, perfluoro-2,3-dimethylbutyl, perfluoro-3,3-dimethylbutyl, perfluoro-1,1,2-trimethylpropyl, perfluoro-1,2,2-trimethylpropyl, perfluoro-1-ethylbutyl, perfluoro-2-ethylbutyl, and perfluoro-3-ethylbutyl groups, linear and branched perfluoroheptyl groups, linear and branched perfluorooctyl groups, linear and branched perfluorononyl groups, and linear and branched perfluorodecyl groups. Examples of perfluoroalkyl groups having 3 to 10 carbon atoms, perfluoroalkyl groups having 5 to 7 carbon atoms, and perfluoroalkyl groups having 6 carbon atoms are groups having the corresponding numbers of carbon atoms among the groups mentioned as examples of perfluoroalkyl groups having 1 to 10 carbon atoms.

[0023] The alkanediyl group having 1 to 6 carbon atoms and the alkanediyl group having 1 to 3 carbon atoms are each linear or branched and unsubstituted, unless otherwise specified. Examples of the alkanediyl group having 1 to 6 carbon atoms include a methanediyl group (methylene group), an ethanediyl group, an n-propanediyl group, an isopropanediyl group, an n-butanediyl group, a sec-butanediyl group, a tert-butanediyl group, an n-pentanediyl group, a 1-methylbutanediyl group, a 2-methylbutanediyl group, a 3-methylbutanediyl group, a 1-ethylpropanediyl group, a 2-ethylpropanediyl group, a 1,1-dimethylpropanediyl group, a 1,2-dimethylpropanediyl group, a 2,2-dimethylpropanediyl group, an n-hexane group, and the like. Examples of the alkanediyl group having 1 to 3 carbon atoms include a diyl group, a 1-methylpentanediyl group, a 2-methylpentanediyl group, a 3-methylpentanediyl group, a 4-methylpentanediyl group, a 1,1-dimethylbutanediyl group, a 1,2-dimethylbutanediyl group, a 1,3-dimethylbutanediyl group, a 2,2-dimethylbutanediyl group, a 2,3-dimethylbutanediyl group, a 3,3-dimethylbutanediyl group, a 1,1,2-trimethylpropanediyl group, a 1,2,2-trimethylpropanediyl group, a 1-ethylbutanediyl group, a 2-ethylbutanediyl group, and a 3-ethylbutanediyl group. Examples of the alkanediyl group having 1 to 3 carbon atoms are groups having the corresponding number of carbon atoms among the groups mentioned as examples of the alkanediyl group having 1 to 6 carbon atoms.

[0024] The alkoxy group having 1 to 8 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the alkoxy group having 1 to 3 carbon atoms are each linear or branched and unsubstituted unless otherwise specified. Examples of the alkoxy group having 1 to 8 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, a 1-methylbutoxy group, a 2-methylbutoxy group, a 3-methylbutoxy group, a 1-ethylpropoxy group, a 2-ethylpropoxy group, a 1,1-dimethylpropoxy group, a 1,2-dimethylpropoxy group, a 2,2-dimethylpropoxy group, an n-hexyloxy group, a 1-methylpentyloxy group, a 2 ... Examples of alkoxy groups having 1 to 6 carbon atoms and alkoxy groups having 1 to 3 carbon atoms are the groups having the corresponding carbon atoms among the groups mentioned as examples of alkoxy groups having 1 to 8 carbon atoms.

[0025] Unless otherwise specified, alkenyl groups having 2 to 6 carbon atoms are linear or branched and unsubstituted. Alkenyl groups having 2 to 6 carbon atoms have one to three double bonds. Examples of alkenyl groups having 2 to 6 carbon atoms include ethenyl, propenyl, butenyl, butadienyl, pentenyl, hexenyl, hexadienyl, and hexatriyl groups.

[0026] Each of the aryl group having 6 to 14 carbon atoms and the aryl group having 6 to 10 carbon atoms is unsubstituted unless otherwise specified. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an indacenyl group, a biphenylenyl group, an acenaphthylenyl group, an anthryl group, and a phenanthryl group. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group. The substituents used in this specification have been described above.

[0027] <First embodiment: electrophotographic photoreceptor> The first embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter, sometimes referred to as photoreceptor). The photoreceptor of the first embodiment includes a conductive substrate and at least one photosensitive layer. The at least one photosensitive layer includes a first photosensitive layer. The first photosensitive layer is provided on the outermost surface side of the at least one photosensitive layer. The surface side is the outer surface side of the photoreceptor (for example, the surface side on which exposure light is incident), and is the opposite side to the side of the photoreceptor on which the conductive substrate is provided.

[0028] The photoreceptor of the first embodiment is, for example, a single-layer electrophotographic photoreceptor (hereinafter, may be referred to as a single-layer photoreceptor) and a positively charged multilayer electrophotographic photoreceptor (hereinafter, may be referred to as a positively charged multilayer photoreceptor).

[0029] (single-layer photoreceptor) A single-layer photoreceptor 1, which is an example of the photoreceptor of the first embodiment, will be described below with reference to Figures 1 to 3. Each of Figures 1 to 3 shows a partial cross-sectional view of the single-layer photoreceptor 1.

[0030] 1, the single-layer photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 included in the single-layer photoreceptor 1 is a single layer (one layer). The single photosensitive layer 3 is a single-layer photosensitive layer 3s that is a first photosensitive layer.

[0031] As shown in Fig. 2, the single-layer photoreceptor 1 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the single-layer photosensitive layer 3s. The intermediate layer 4 is provided between the conductive substrate 2 and the single-layer photosensitive layer 3s. As shown in Fig. 1, the single-layer photosensitive layer 3s may be provided directly on the conductive substrate 2. Alternatively, as shown in Fig. 2, the single-layer photosensitive layer 3s may be provided on the conductive substrate 2 via the intermediate layer 4.

[0032] As shown in FIG. 3, the single-layer photoreceptor 1 may further include a protective layer 5 in addition to the conductive substrate 2 and the single-layer photoreceptor layer 3s. The protective layer 5 is provided on the single-layer photoreceptor layer 3s. As shown in FIGS. 1 and 2, the single-layer photoreceptor layer 3s is preferably provided as the outermost layer of the single-layer photoreceptor 1. By providing the single-layer photoreceptor layer 3s containing a polyarylate resin (PA) described later and a specific electron transport agent described later as the outermost layer, the fogging resistance of the single-layer photoreceptor 1 is easily improved. Note that, as shown in FIG. 3, the protective layer 5 may be provided as the outermost layer of the single-layer photoreceptor 1.

[0033] The thickness of the single-layer type photosensitive layer 3s is not particularly limited, but is preferably from 5 μm to 100 μm, and more preferably from 10 μm to 50 μm.

[0034] The single-layer photosensitive layer 3s, which is the first photosensitive layer, contains a charge generating agent, a binder resin, an electron transport agent, and a hole transport agent. Hereinafter, the "hole transport agent contained in the single-layer photosensitive layer 3s" may be referred to as the "hole transport agent (SL)". The "binder resin contained in the single-layer photosensitive layer 3s" may be referred to as the "binder resin (SL)". The single-layer photosensitive layer 3s may contain additives as necessary. The single-layer photoreceptor 1 has been described above with reference to Figs. 1 to 3.

[0035] (Positively charged laminated photoconductor) A positively charged multi-layer photoreceptor 10, which is an example of the photoreceptor of the first embodiment, will be described below with reference to Figures 4 to 6. Figures 4 to 6 each show a partial cross-sectional view of the positively charged multi-layer photoreceptor 10.

[0036] As shown in FIG. 4, the positively charged laminated photoreceptor 10 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 of the positively charged laminated photoreceptor 10 is two layers. The two photosensitive layers 3 are a charge generating layer 12 and a charge transport layer 11. The charge generating layer 12 is a first photosensitive layer. The charge transport layer 11 is a second photosensitive layer. The charge generating layer 12, which is the first photosensitive layer, is provided on the most surface side of the two photosensitive layers 3 (the charge generating layer 12 and the charge transport layer 11). The charge transport layer 11 is provided on the conductive substrate 2 side of the charge generating layer 12. Since the charge generating layer 12 is located on the most surface side (the side opposite to the side where the conductive substrate 2 of the positively charged laminated photoreceptor 10 is provided), for example, the charge transport layer 11 is provided on the conductive substrate 2, and the charge generating layer 12 is provided on the charge transport layer 11. When the positively charged multi-layer photoconductor 10 is provided in an image forming apparatus 100 (see FIG. 7), the positively charged multi-layer photoconductor 10 is positively charged by a charging device 42 (see FIG. 7).

[0037] As shown in Fig. 5, the positively charged laminated photoreceptor 10 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3 (e.g., charge transport layer 11). As shown in Fig. 4, the photosensitive layer 3 (e.g., charge transport layer 11) may be provided directly on the conductive substrate 2. Alternatively, as shown in Fig. 5, the photosensitive layer 3 (e.g., charge transport layer 11) may be provided on the conductive substrate 2 via the intermediate layer 4.

[0038] As shown in FIG. 6, the positively charged laminated photoreceptor 10 may further include a protective layer 5 in addition to the conductive substrate 2 and the photosensitive layer 3. The protective layer 5 is provided on the photosensitive layer 3 (e.g., charge generating layer 12). As shown in FIGS. 4 and 5, the photosensitive layer 3 is preferably provided as the outermost layer of the positively charged laminated photoreceptor 10. By providing the photosensitive layer 3 (e.g., charge generating layer 12) containing a polyarylate resin (PA) described later and a specific electron transport agent described later as the outermost layer, the fogging resistance of the positively charged laminated photoreceptor 10 is easily improved. Note that, as shown in FIG. 6, the protective layer 5 may be provided as the outermost layer of the positively charged laminated photoreceptor 10.

[0039] The thickness of the charge generating layer 12 is preferably from 2 μm to 100 μm, more preferably from 15 μm to 30 μm, and the thickness of the charge transport layer 11 is preferably from 2 μm to 100 μm, more preferably from 3 μm to 20 μm, and even more preferably from 5 μm to 15 μm.

[0040] The charge generation layer 12, which is the first photosensitive layer, contains a charge generation material, a binder resin, an electron transport material, and a hole transport material. Hereinafter, the "hole transport material contained in the charge generation layer 12" may be referred to as the "hole transport material (CG)". Also, the "binder resin contained in the charge generation layer 12" may be referred to as the "binder resin (CG)". The charge generation layer 12 may contain additives as necessary.

[0041] The charge transport layer 11, which is the second photosensitive layer, contains a hole transport agent and a binder resin. Hereinafter, the "hole transport agent contained in the charge transport layer 11" may be referred to as the "hole transport agent (CT)". Also, the "binder resin contained in the charge transport layer 11" may be referred to as the "binder resin (CT)". The charge transport layer 11 may contain additives as necessary. The positively charged multilayer photoreceptor 10 has been described above with reference to Figs. 4 to 6.

[0042] The photoreceptor will be described in more detail below. When it is not necessary to distinguish between the binder resin (SL), the binder resin (CG), and the binder resin (CL), they will be simply referred to as "binder resin". When it is not necessary to distinguish between the hole transport material (SL), the hole transport material (CG), and the hole transport material (CL), they will be simply referred to as "hole transport material".

[0043] (binder resin) The binder resin (specifically, binder resins (SL) and (CG)) contained in the first photosensitive layer includes a polyarylate resin. The polyarylate resin has repeating units represented by formulas (1), (2), (3), and (4). In the polyarylate resin, the third content is greater than 0% and less than 50%. The third content is the content of the repeating unit represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3). In the polyarylate resin, the fourth content is greater than or equal to 35% and less than 70%. The fourth content is the content of the repeating unit represented by formula (4) relative to the total number of repeating units represented by formulas (2) and (4).

[0044] [ka]

[0045] In formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1). 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2).

[0046] [ka]

[0047] In formulae (X1) and (X2), * represents a bond. The bond represented by * in formulae (X1) and (X2) is bonded to the carbon atom to which X in formula (1) is bonded.

[0048] Hereinafter, "repeating units represented by formulas (1), (2), (3), and (4)" may be referred to as "repeating units (1), (2), (3), and (4)," respectively. Also, "a polyarylate resin having repeating units (1), (2), (3), and (4), in which the third content is greater than 0% and less than 50%, and the fourth content is 35% or more and less than 70%" may be referred to as "polyarylate resin (PA)."

[0049] As already mentioned, the binder resins (SL) and (CG) contained in the first photosensitive layer each essentially contain a polyarylate resin (PA). The binder resin (CL) contained in the charge transport layer is not particularly limited, and may contain a polyarylate resin (PA) or other binder resins described later. The binder resins (CG) and (CL) may be the same or different from each other.

[0050] Photosensitive layers (particularly the first photosensitive layer) containing polyarylate resin (PA) are less susceptible to fine scratches. This prevents toner from penetrating into fine scratches, improving the fogging resistance of the photoreceptor. In addition, polyarylate resin (PA) has excellent solubility in solvents, allowing the photosensitive layer (particularly the first photosensitive layer) to be formed well.

[0051] In formula (1), R 1 and R 2 When R represents a methyl group and X represents a divalent group represented by formula (X1), the repeating unit (1) is a repeating unit represented by formula (1-1) (hereinafter, sometimes referred to as repeating unit (1-1)). 1 and R 2 When represents a hydrogen atom and X represents a divalent group represented by formula (X2), the repeating unit (1) is a repeating unit represented by formula (1-2) (hereinafter, may be referred to as repeating unit (1-2)). The polyarylate resin (PA) may have only one type of repeating unit (1), or may have two types of repeating units (1).

[0052] [ka]

[0053] The content of the repeating unit (1) relative to the total number of the repeating units (1) and (3) is referred to as the first content. The first content is the number M of the repeating units (1) contained in the polyarylate resin (PA). 1 and the number M of repeating units (3) 3The number of repeating units (1) M 1 Percentage of (i.e., 100 × M 1 / (M 1 +M 3 In addition, when the polyarylate resin (PA) has two kinds of repeating units (1), the number M of repeating units (1) corresponds to 1 is the total number of two types of repeating units (1).

[0054] The first content is preferably less than 100%, more preferably 99% or less, even more preferably 90% or less, even more preferably 80% or less, even more preferably 70% or less, even more preferably less than 70%, and particularly preferably 65% ​​or less. The first content is preferably greater than 50%, more preferably 51% or more, and even more preferably 55% or more. In order to improve the fogging resistance of the photoreceptor, the first content is preferably greater than 50% and less than 70%, and more preferably greater than 50% and less than 70%.

[0055] The content of the repeating unit (2) relative to the total number of the repeating units (2) and (4) is referred to as the second content. The second content is the number M of the repeating units (2) contained in the polyarylate resin (PA). 2 and the number M of repeating units (4) 4 The number of repeating units (2) M 2 Percentage of (i.e., 100 × M 2 / (M 2 +M 4 )).

[0056] The second content is preferably 65% ​​or less, more preferably 60% or less. The second content is preferably greater than 30%, more preferably 31% or more, even more preferably 35% or more, even more preferably 40% or more, and particularly preferably 55% or more. The fogging resistance of the photoreceptor, the second content is preferably greater than 30% and less than 60%. In order to improve the wear resistance of the photoreceptor when the photosensitive layer contains polyarylate resin (PA), the second content is preferably 55% or more and less than 65%.

[0057] As already described, the third content is greater than 0% and less than 50%. The third content is determined by the number M of repeating units (1) contained in the polyarylate resin (PA). 1 and the number M of repeating units (3) 3 The number of repeating units (3) M 3 Percentage of (i.e., 100 × M 3 / (M 1 +M 3 )).

[0058] When the third content is less than 50%, the solubility of the polyarylate resin (PA) in a solvent is improved, and the photosensitive layer can be formed well. When the third content is greater than 0%, that is, the third content is not 0%, the abrasion resistance of the photoreceptor when the polyarylate resin (PA) is contained in the photosensitive layer can be improved. The third content is preferably 1% or more, more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, still more preferably greater than 30%, and particularly preferably 35% or more. In addition, the third content is preferably 49% or less, and more preferably 45% or less.

[0059] In order to improve the fogging resistance of the photoreceptor, the third content is preferably 30% or more and less than 50%, and more preferably more than 30% and less than 50%.

[0060] As already described, the fourth content is 35% or more and less than 70%. The fourth content is determined by the number M of the repeating units (2) contained in the polyarylate resin (PA). 2 and the number M of repeating units (4) 4 The number of repeating units (4) M 4 Percentage of (i.e., 100 × M 4 / (M 2 +M 4 )).

[0061] When the fourth content is 35% or more, the fogging resistance of the photoreceptor is improved. When the fourth content is 35% or more, the solubility of the polyarylate resin (PA) in a solvent is improved, and the photosensitive layer can be formed satisfactorily. On the other hand, when the fourth content is less than 70%, the abrasion resistance and fogging resistance of the photoreceptor are improved. The fourth content is preferably 40% or more. Furthermore, the fourth content is preferably 69% or less, more preferably 65% ​​or less, even more preferably 60% or less, and even more preferably 45% or less.

[0062] In order to improve the fogging resistance of the photoconductor, the fourth content is preferably 40% or more and less than 70%. In order to improve the abrasion resistance of the photoconductor when the photosensitive layer contains a polyarylate resin (PA), the fourth content is preferably 35% or more and 45% or less.

[0063] The first content, the second content, the third content, and the fourth content are each determined by measuring the amount of the polyarylate resin (PA) using a proton nuclear magnetic resonance spectrometer. 1 The H-NMR spectrum was measured and 1 It can be calculated from the ratio of peaks characteristic of each repeating unit in the H-NMR spectrum.

[0064] In order to improve the solubility in a solvent and the fogging resistance and abrasion resistance of the photoreceptor, it is preferable that the first content is different from the second content and different from the fourth content. For the same reason, it is preferable that the third content is different from the second content and different from the fourth content.

[0065] In order to further improve the fogging resistance of the photoconductor, R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), and the fourth content is preferably 40% or more and less than 70%.

[0066] In order to improve the fogging resistance and abrasion resistance of the photoconductor in a well-balanced manner, R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), and the third content is preferably 30% or more and less than 50%.

[0067] In order to further improve the wear resistance of the photoconductor, R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2), and the fourth content is preferably 35% or more and 45% or less.

[0068] In order to improve the fogging resistance and abrasion resistance of the photoconductor without impairing the sensitivity characteristics of the photoconductor, it is preferable that the polyarylate resin (PA) does not have a repeating unit having a biphenyl structure. Examples of the repeating unit having a biphenyl structure include a repeating unit represented by formula (5). Examples of the repeating unit represented by formula (5) include a repeating unit represented by formula (5-1) and (5-2).

[0069] [ka]

[0070] [ka]

[0071] In order to further improve the abrasion resistance of the photoreceptor when contained in the photosensitive layer, the polyarylate resin (PA) preferably does not have a repeating unit derived from isophthalic acid.

[0072] The polyarylate resin (PA) may have a terminal group. Examples of the terminal group of the polyarylate resin (PA) include terminal groups represented by formulas (T-1) and (T-2). The terminal group represented by formula (T-1) is preferably a terminal group represented by formula (T-DMP) (hereinafter, may be referred to as terminal group (T-DMP)). The terminal group represented by formula (T-2) is preferably a terminal group represented by formula (T-PFH) (hereinafter, may be referred to as terminal group (T-PFH)).

[0073] [ka]

[0074] In formula (T-1), R 11 represents an alkyl group having 1 to 6 carbon atoms or a halogen atom, and p represents an integer of 0 to 5. 11 preferably represents an alkyl group having 1 to 6 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and even more preferably represents a methyl group. p preferably represents an integer of 1 to 3, and more preferably represents 2.

[0075] In formula (T-2), R 12 represents an alkanediyl group having 1 to 6 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. 12 Rf preferably represents an alkanediyl group having from 1 to 3 carbon atoms, and more preferably represents a methylene group. Rf preferably represents a perfluoroalkyl group having from 3 to 10 carbon atoms, more preferably a perfluoroalkyl group having from 5 to 7 carbon atoms, and even more preferably a perfluoroalkyl group having 6 carbon atoms.

[0076] The * in the formulae (T-1), (T-2), (T-DMP), and (T-PFH) represents a bond. The bond represented by the * in the formulae (T-1), (T-2), (T-DMP), and (T-PFH) is bonded to a repeating unit derived from a dicarboxylic acid (more specifically, repeating unit (2) or (4)) located at the end of the polyarylate resin (PA).

[0077] In order to further improve the fogging resistance and abrasion resistance of the photoreceptor, it is preferable that the polyarylate resin (PA) has a terminal group having a halogen atom. For the same reason, in formula (1), R 1 and R 2 It is more preferable that X represents a divalent group represented by the formula (X1), and the polyarylate resin (PA) has a terminal group having a halogen atom.

[0078] An example of a terminal group having a halogen atom is R 11 represents a halogen atom. Another example of an end group having a halogen atom is the end group (T-2).

[0079] Suitable examples of the polyarylate resin (PA) include polyarylate resins (PA-1) to (PA-2) shown in Table 1. The polyarylate resins (PA-1) to (PA-2) each have the repeating units (1) to (4) shown in Table 1. More suitable examples of the polyarylate resin (PA) include polyarylate resins (PA-a) to (PA-d) shown in Table 2. The polyarylate resins (PA-a) to (PA-d) each have the repeating units (1) to (4) shown in Table 2 and the terminal groups shown in Table 2. In Tables 1 and 2, "units (1) to (4)" respectively refer to "repeating units (1) to (4)".

[0080] [Table 1]

[0081] [Table 2]

[0082] In the polyarylate resin (PA), the repeating unit derived from bisphenol (more specifically, the repeating unit (1) or (3)) and the repeating unit derived from dicarboxylic acid (more specifically, the repeating unit (2) or (4)) are adjacent to each other and bonded to each other. That is, the repeating unit (1) may be bonded to the repeating unit (2) or to the repeating unit (4). The repeating unit (3) may be bonded to the repeating unit (2) or to the repeating unit (4). The number of the repeating units derived from bisphenol is approximately the same as the number of the repeating units derived from dicarboxylic acid, and satisfies the formula "the number of repeating units derived from dicarboxylic acid = the number of repeating units derived from bisphenol + 1". The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0083] The polyarylate resin (PA) may further have repeating units other than the repeating units (1) to (4) as repeating units. However, in order to improve the solubility in a solvent and improve the fogging resistance and abrasion resistance of the photoreceptor, the content of the repeating units (1) to (4) in the total number of repeating units contained in the polyarylate resin (PA) is preferably 80% or more, more preferably 90% or more, even more preferably 95% or more, even more preferably 99% or more, and particularly preferably 100%. That is, it is particularly preferable that the polyarylate resin (PA) has only the repeating units (1) to (4) as repeating units.

[0084] The content of repeating unit (1) relative to the total number of repeating units derived from bisphenol contained in the polyarylate resin (PA) is preferably greater than 50% and less than 100%, more preferably 55% to 90%, even more preferably 60% to 80%, even more preferably 60% to 70%, and even more preferably 60% to 70%. The content of repeating unit (3) relative to the total number of repeating units derived from bisphenol contained in the polyarylate resin (PA) is preferably greater than 0% and less than 50%, more preferably 10% to 45%, even more preferably 20% to 40%, even more preferably 30% to 40%, and even more preferably more than 30% to 40%.

[0085] The content of the repeating unit (2) relative to the total number of repeating units derived from dicarboxylic acid contained in the polyarylate resin (PA) is preferably more than 30% and not more than 65%, more preferably 35% or more and not more than 65%, and even more preferably 40% or more and not more than 60%. The content of the repeating unit (4) relative to the total number of repeating units derived from dicarboxylic acid contained in the polyarylate resin (PA) is preferably 35% or more and less than 70%, more preferably 35% or more and not more than 65%, and even more preferably 40% or more and not more than 60%.

[0086] The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 30,000 or more, even more preferably 35,000 or more, even more preferably 50,000 or more, and particularly preferably 55,000 or more. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the wear resistance of the photoconductor is improved when the polyarylate resin (PA) is contained in the photosensitive layer of the photoconductor. When the viscosity average molecular weight of the polyarylate resin (PA) is 35,000 or more, the breaking strain becomes a desired value or more, and the wear resistance of the photoconductor is improved. In addition, when the viscosity average molecular weight of the polyarylate resin (PA) is 35,000 or more, the fogging resistance of the photoconductor is further improved. On the other hand, the viscosity average molecular weight of the polyarylate resin (PA) is preferably 80,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. When the viscosity average molecular weight of the polyarylate resin (PA) is 80,000 or less, the fogging resistance of the photoreceptor is further improved. In addition, the solubility of the polyarylate resin (PA) in a solvent is also improved. The viscosity average molecular weight of the polyarylate resin (PA) is measured according to JIS (Japanese Industrial Standards) K7252-1:2016.

[0087] The ratio of the mass of the binder resin to the mass of the first photosensitive layer is preferably 0.35 or more and 0.50 or less. When the ratio of the mass of the binder resin to the mass of the first photosensitive layer is 0.35 or more and 0.50 or less, the fogging resistance of the photoreceptor is further improved. When the ratio of the mass of the binder resin to the mass of the first photosensitive layer is 0.50 or less, the content of the electron transport agent and the hole transport agent in the first photosensitive layer is relatively high, and the sensitivity characteristic of the photoreceptor is improved. When the photoreceptor is a single-layer type photoreceptor, the ratio of the mass of the binder resin to the mass of the first photosensitive layer is the ratio of the mass of the binder resin (SL) to the mass of the single-layer type photosensitive layer that is the first photosensitive layer. When the photoreceptor is a positively charged laminated type photoreceptor, the ratio of the mass of the binder resin to the mass of the first photosensitive layer is the ratio of the mass of the binder resin (CG) to the mass of the charge generating layer that is the first photosensitive layer. When the binder resin (SL) contains other binder resins described later in addition to the polyarylate resin (PA), the mass of the binder resin (SL) is the total mass of the polyarylate resin (PA) and the other binder resins. When the binder resin (CG) contains other binder resins described later in addition to the polyarylate resin (PA), the mass of the binder resin (CG) is the total mass of the polyarylate resin (PA) and the other binder resins. When the binder resin (SL) contains two or more resins, the mass of the binder resin (SL) is the total mass of the two or more resins. When the binder resin (CG) contains two or more resins, the mass of the binder resin (CG) is the total mass of the two or more resins.

[0088] Next, the method for producing polyarylate resin (PA) will be described. For example, the method for producing polyarylate resin (PA) includes a method of polycondensing bisphenol for forming a repeating unit derived from bisphenol and dicarboxylic acid for forming a repeating unit derived from dicarboxylic acid. For polycondensation, a known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization) can be adopted.

[0089] Examples of bisphenols for constituting the repeating units derived from bisphenols include compounds represented by formulae (BP-1) and (BP-3) (hereinafter, these may be referred to as compounds (BP-1) and (BP-3), respectively). Examples of dicarboxylic acids for constituting the repeating units derived from dicarboxylic acids include compounds represented by formulae (DC-2) and (DC-4) (hereinafter, these may be referred to as compounds (DC-2) and (DC-4), respectively). R in formula (BP-1) 1 , R 2 , and X is R in formula (1). 1 , R 2 , and X.

[0090] [ka]

[0091] In the production of polyarylate resin (PA), the first content is adjusted by changing the amount of compound (BP-1) added (unit: mole) relative to the total amount of compounds (BP-1) and (BP-3) added (unit: mole). The second content is adjusted by changing the amount of compound (DC-2) added (unit: mole) relative to the total amount of compounds (DC-2) and (DC-4) added (unit: mole). The third content is adjusted by changing the amount of compound (BP-3) added (unit: mole) relative to the total amount of compounds (BP-1) and (BP-3) added (unit: mole). The fourth content is adjusted by changing the amount of compound (DC-4) added (unit: mole) relative to the total amount of compounds (DC-2) and (DC-4) added (unit: mole).

[0092] Bisphenols may be derivatized to aromatic diacetates for use. Dicarboxylic acids may be derivatized for use. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. Dicarboxylic acid dichlorides are compounds in which two "-C(=O)-OH" groups of a dicarboxylic acid are each replaced with a "-C(=O)-Cl" group.

[0093] In the polycondensation of bisphenol and dicarboxylic acid, a terminal terminator may be added. Examples of the terminal terminator include 2,6-dimethylphenol and 1H,1H-perfluoro-1-heptanol. By using 2,6-dimethylphenol as the terminal terminator, a terminal group (T-DMP) is formed. By using 1H,1H-perfluoro-1-heptanol as the terminal terminator, a terminal group (T-PFH) is formed.

[0094] In the polycondensation of bisphenol and dicarboxylic acid, a base and / or a catalyst may be added. An example of the base is sodium hydroxide. An example of the catalyst is benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salt, triethylamine, and trimethylamine.

[0095] The photosensitive layer (more specifically, each of the single-layer photosensitive layer, the charge generating layer, and the charge transport layer) may contain only one type of polyarylate resin (PA) as a binder resin, or may contain two or more types of polyarylate resin (PA). The photosensitive layer (more specifically, each of the single-layer photosensitive layer, the charge generating layer, and the charge transport layer) may contain only polyarylate resin (PA) as a binder resin, or may further contain a binder resin other than polyarylate resin (PA) (hereinafter, may be referred to as other binder resin).

[0096] Examples of other binder resins include thermoplastic resins (more specifically, polyarylate resins other than polyarylate resins (PA), polycarbonate resins, styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid-based resins, and urethane-acrylic acid-based copolymers).

[0097] (Electron transport agent) The electron transport material contains a compound represented by formula (11), (12), (13), (14), (15), (16), or (17) (hereinafter, these may be referred to as electron transport materials (11), (12), (13), (14), (15), (16), and (17), respectively). When the first photosensitive layer contains the electron transport materials (11) to (17) in addition to the polyarylate resin (PA), the fogging resistance is improved.

[0098] [ka]

[0099] Q in Equation (11) 1 and Q 2 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 , Q42 , and Q 43 , Q in Eq. (15) 51 , Q 52 , Q 53 , and Q 54 , Q in Eq. (16) 61 and Q 62 , and Q in formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 each independently represents an oxygen atom or a sulfur atom.

[0100] Q in Equation (11) 1 and Q 2 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 , Q 42 , and Q 43 , Q in Eq. (15) 51 , Q 52 , Q 53 , and Q 54 , Q in Eq. (16) 61 and Q 62 , and Q in formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76Each of Y preferably independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 preferably represents an oxygen atom.

[0101] Q in Equation (11) 1 and Q 2 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 , Q 42 , and Q 43 , Q in Eq. (15) 51 , Q 52 , Q 53 , and Q 54 , Q in Eq. (16) 61 and Q 62 , and Q in formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76 The alkyl group having 1 to 6 carbon atoms represented by is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group, and particularly preferably a methyl group, an isopropyl group, a tert-butyl group, or a 1,1-dimethylpropyl group.

[0102] Q in Equation (11) 1 and Q 2 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 , Q 42 , and Q 43 , Q in Eq. (15) 51 , Q52 , Q 53 , and Q 54 , Q in Eq. (16) 61 and Q 62 , and Q in formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76 The aryl group having 6 to 14 carbon atoms represented by is preferably an aryl group having 6 to 10 carbon atoms, more preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. The alkyl group having 1 to 6 carbon atoms as the substituent is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. The halogen atom as the substituent is preferably a fluorine atom, a chlorine atom, or a bromine atom, and particularly preferably a chlorine atom. When an aryl group having 6 to 14 carbon atoms is substituted with a substituent, the number of the substituents is preferably 1 to 5, more preferably 1 or 2. The aryl group having 6 to 14 carbon atoms substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom is preferably a chlorophenyl group, a dichlorophenyl group, or an ethylmethylphenyl group, more preferably a 4-chlorophenyl group, a 2,5-dichlorophenyl group, or a 2-ethyl-6-methylphenyl group.

[0103] More suitable examples of the electron transport agent include compounds represented by formulas (E-1) to (E-9) (hereinafter, each of which may be referred to as electron transport agents (E-1) to (E-9)).

[0104] [ka]

[0105] The content of the electron transport agent is preferably from 5 to 150 parts by mass, more preferably from 10 to 100 parts by mass, and even more preferably from 30 to 70 parts by mass, per 100 parts by mass of the binder resin (SL) (or per 100 parts by mass of the binder resin (CG)). The first photosensitive layer may contain only one type of electron transport agent, or may contain two or more types of electron transport agents.

[0106] (Hole transport agent) Examples of the hole transport agent include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthylenediamine derivatives, N,N,N',N'-tetraphenylphenanthrylenediamine derivatives, and di(aminophenylethenyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazo Examples of the hole transport agent include 9-(4-diethylaminostyryl)anthracene, ...

[0107] Suitable examples of the hole transport agent include compounds represented by formulas (20), (21), (22), (23), (24), and (25) (hereinafter, these may be referred to as hole transport agents (20), (21), (22), (23), (24), and (25), respectively). When the photosensitive layer contains the hole transport agent (20), (21), (22), (23), (24), or (25) together with the polyarylate resin (PA), the photosensitive layer can be formed in a better manner, and the fogging resistance of the photoreceptor is further improved. It is more preferable that the photosensitive layer contains the hole transport agent (20), (21), (22), (23), or (24). The hole transport agent (20), (21), (22), (23), or (24) has excellent compatibility with the polyarylate resin (PA), and therefore improves the wear resistance and sensitivity characteristics of the photoreceptor in addition to the fogging resistance.

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] In formula (20), R 16 , R 17 , R 18 , and R 19 each independently represents an alkyl group having 1 to 6 carbon atoms; a6, a7, a8, and a9 each independently represents an integer of 0 to 5.

[0113] In formula (20), when a6 represents an integer of 2 or more and 5 or less, a plurality of R 16may represent the same group or different groups. When a7 represents an integer of 2 or more and 5 or less, multiple R 17 may represent the same group or different groups. When a8 represents an integer of 2 or more and 5 or less, multiple R 18 may represent the same group or different groups. When a9 represents an integer of 2 or more and 5 or less, multiple R 19 may represent the same group or different groups.

[0114] In formula (20), R 16 , R 17 , R 18 , and R 19 each independently preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group; a6, a7, a8, and a9 each independently preferably represent an integer of 1 to 3, more preferably 1.

[0115] In formula (21), R 21 , R 22 , and R 23 R each independently represents an alkyl group having 1 to 6 carbon atoms. 24 , R 25 , and R 26 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms. 1 , b 2 , and b 3 Each independently represents 0 or 1. 4 , b 5 , and b 6 each independently represents an integer of 0 or more and 5 or less.

[0116] In formula (21), R 21 , R 22 , and R 23 R preferably each independently represents an alkyl group having 1 to 3 carbon atoms, and more preferably represents a methyl group. 21 , R 22 , and R 23is preferably bonded to the meta position of the phenyl group relative to the ethenyl group or the butadienyl group. 24 , R 25 , and R 26 Each of b preferably represents a hydrogen atom. 1 , b 2 , and b 3 It is preferable that both of them are 0 or both of them are 1. 4 , b 5 , and b 6 It is preferable that each of these represents 1.

[0117] In formula (22), R 31 , R 32 , and R 33 R each independently represents an alkyl group having 1 to 6 carbon atoms. 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. 1 , d 2 , and d 3 each independently represents an integer of 0 or more and 5 or less.

[0118] In formula (22), d 1 When represents an integer between 2 and 5, multiple R 31 may represent the same group or different groups. 2 When represents an integer between 2 and 5, multiple R 32 may represent the same group or different groups. 3 When represents an integer between 2 and 5, multiple R 33 may represent the same group or different groups.

[0119] In formula (22), R 34 preferably represents a hydrogen atom. 1 , d 2 , and d 3 Preferably, each represents 0.

[0120] In formula (23), R 50 and R 51R each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group. 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms. 1 and f 2 Each independently represents an integer of 0 to 2. 3 and f 4 each independently represents an integer of 0 or more and 5 or less.

[0121] In formula (23), f 3 When represents an integer between 2 and 5, multiple R 50 may represent the same group or different groups. 4 When represents an integer between 2 and 5, multiple R 51 may represent the same group or different groups.

[0122] In formula (23), R 50 and R 51 Each of R independently preferably represents an alkyl group having 1 to 6 carbon atoms. 52 and R 53 R preferably represents a hydrogen atom or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms. 54 ~R 58 Each of f independently preferably represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 and f 2 It is preferable that all of f represent 0, all of f represent 1, or all of f represent 2. 3 and f 4 It is preferable that each independently represents 0 or 1.

[0123] In formula (23), R50 and R 51 The alkyl group having 1 to 6 carbon atoms represented by R is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. 52 and R 53 The phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms, represented by the formula (I), is preferably a phenyl group or a phenyl group substituted with an alkyl group having 1 to 3 carbon atoms. The phenyl group substituted with an alkyl group having 1 to 3 carbon atoms is preferably a methylphenyl group, and more preferably a 4-methylphenyl group. 54 ~R 58 The alkyl group having 1 to 6 carbon atoms represented by R is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group, an ethyl group, or an n-butyl group. 54 ~R 58 The alkoxy group having 1 to 6 carbon atoms represented by the formula (I) is preferably an alkoxy group having 1 to 3 carbon atoms, and more preferably an ethoxy group.

[0124] In formula (24), R 61 , R 62 , R 63 , R 64 , R 65 , and R 66 R each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. 67 and R 68 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. e1, e2, e3, and e4 each independently represent an integer of 0 to 5. e5 and e6 each independently represent an integer of 0 to 4. e7 and e8 each independently represent 0 or 1.

[0125] In formula (24), when e1 represents an integer of 2 or more and 5 or less, a plurality of R 61 may represent the same group or different groups. When e2 represents an integer of 2 to 5, multiple R 62 may represent the same group or different groups. When e3 represents an integer of 2 to 5, multiple R 63may represent the same group or different groups. When e4 represents an integer of 2 to 5, multiple R 64 may represent the same group or different groups. When e5 represents an integer of 2 to 4, multiple R 65 may represent the same group or different groups. When e6 represents an integer of 2 to 4, multiple R 66 may represent the same group or different groups.

[0126] In formula (24), R 61 ~R 66 R each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and further preferably represents a methyl group or an ethyl group. 67 and R 68 preferably represents a hydrogen atom. e1, e2, e3, and e4 each independently preferably represent an integer of 0 or more and 2 or less. e5 and e6 preferably represent 0.

[0127] In formula (25), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. g1, g2, g4, and g5 each independently represent an integer of 0 to 5. g3 and g6 each independently represent an integer of 0 to 4.

[0128] In formula (25), when g1 represents an integer of 2 to 5, a plurality of R 41 may represent the same group or different groups. When g2 represents an integer of 2 to 5, multiple R 42 may represent the same group or different groups. When g4 represents an integer of 2 to 5, multiple R 44 may represent the same group or different groups. When g5 represents an integer of 2 to 5, multiple R45 may represent the same group or different groups. When g3 represents an integer of 2 to 4, multiple R 43 may represent the same group or different groups. When g6 represents an integer of 2 to 4, multiple R 46 may represent the same group or different groups.

[0129] In formula (25), R 41 ~R 46 Each of g1, g2, g4, and g5 independently preferably represents an integer of 0 to 2. Each of g3 and g6 preferably represents 0. R 44 , R 45 , and R 46 The diphenylaminophenylethenyl group having R 41 , R 42 , and R 43 For a diphenylaminophenylethenyl group having the formula:

[0130] More suitable examples of the hole transport agent include compounds represented by formulas (H-1) to (H-11) (hereinafter, each of which may be referred to as hole transport agents (H-1) to (H-11)).

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] The content of the hole transport agent (SL) per 100 parts by mass of the binder resin (SL), the content of the hole transport agent (CG) per 100 parts by mass of the binder resin (CG), and the content of the hole transport agent (CL) per 100 parts by mass of the binder resin (CL) are preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 50 parts by mass or more and 150 parts by mass or less, and even more preferably 70 parts by mass or more and 130 parts by mass or less.

[0138] (Charge generating material) Examples of the charge generating agent include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The single-layer photosensitive layer and the charge generating layer may each contain only one type of charge generating agent, or may contain two or more types of charge generating agents.

[0139] Phthalocyanine pigments are pigments having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanine is represented by formula (CGM-1). Titanyl phthalocyanine is represented by formula (CGM-2).

[0140] [ka]

[0141] [ka]

[0142] The phthalocyanine pigment may be crystalline or non-crystalline. Examples of the metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter, may be referred to as X-type metal-free phthalocyanine). Examples of the titanyl phthalocyanine crystals include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, may be referred to as α-type, β-type, and Y-type titanyl phthalocyanine, respectively).

[0143] For example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. As the charge generating agent, a phthalocyanine pigment is preferable because it has a high quantum yield in a wavelength region of 700 nm or more, a metal-free phthalocyanine or titanyl phthalocyanine is more preferable, titanyl phthalocyanine is further preferable, and Y-type titanyl phthalocyanine is particularly preferable.

[0144] The Y-type titanyl phthalocyanine has a main peak at, for example, 27.2° of Bragg angle (2θ±0.2°) in the CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak having the first or second largest intensity in the range of Bragg angle (2θ±0.2°) from 3° to 40°. The Y-type titanyl phthalocyanine does not have a peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0145] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (titanyl phthalocyanine) is loaded into a sample holder of an X-ray diffractometer (for example, Rigaku Corporation's "RINT (registered trademark) 1100"), and the X-ray diffraction spectrum is measured under the conditions of an X-ray tube Cu, a tube voltage of 40 kV, a tube current of 30 mA, and a wavelength of CuKα characteristic X-ray of 1.542 Å. The measurement range (2θ) is, for example, 3° to 40° (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0146] The content of the charge generating agent per 100 parts by mass of the binder resin (SL) and the content of the charge generating agent per 100 parts by mass of the binder resin (CG) are preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0147] (Additives) Examples of additives include ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents.

[0148] (Scratch Resistance Depth) The scratch resistance depth of the first photosensitive layer is preferably 0.50 μm or less. The scratch resistance depth of the first photosensitive layer is a value indicating the hardness of the first photosensitive layer. The scratch resistance depth of the first photosensitive layer being 0.50 μm or less means that the first photosensitive layer has such hardness that scratches having a scratch resistance depth of 0.50 μm or less are formed on the surface of the first photosensitive layer by a method for measuring the scratch resistance depth described later. When the scratch resistance depth of the first photosensitive layer is 0.50 μm or less, fine scratches are unlikely to occur on the surface of the photosensitive body. As a result, toner is unlikely to enter the scratches generated on the surface of the photosensitive body, and fogging is unlikely to occur on the formed image. In addition, when the scratch resistance depth of the first photosensitive layer is 0.50 μm or less, the wear resistance of the photosensitive body is improved. To improve fogging resistance, the scratch resistance depth of the first photosensitive layer is preferably 0.00 μm or more and 0.50 μm or less, more preferably 0.05 μm or more and 0.40 μm or less, and even more preferably 0.10 μm or more and 0.30 μm or less.

[0149] The scratch resistance depth of the first photosensitive layer is measured by the following method. The scratch resistance depth of the first photosensitive layer is measured by performing the first, second, third, and fourth steps using a scratching device specified in JIS (Japanese Industrial Standards) K5600-5-5. The scratching device includes a fixed base and a scratching needle. The scratching needle has a hemispherical sapphire tip with a diameter of 1 mm. In the first step, the photosensitive body is fixed to the upper surface of the fixed base so that the longitudinal direction of the photosensitive body is parallel to the longitudinal direction of the fixed base. In the second step, the scratching needle is brought into contact perpendicularly with the surface of the first photosensitive layer. In the third step, while the scratching needle is in contact perpendicularly with the surface of the first photosensitive layer, the fixed base and the photosensitive body fixed to the upper surface of the fixed base are moved 30 mm in the longitudinal direction of the fixed base at a speed of 30 mm / min while applying a load of 10 g from the scratching needle to the first photosensitive layer, and scratches are formed on the surface of the first photosensitive layer by the scratching needle. In the fourth step, the scratch resistance depth, which is the maximum depth of the scratch, is measured. The outline of the method for measuring the scratch resistance depth has been described above. The method for measuring the scratch resistance depth will be described in detail in the Examples.

[0150] The scratch resistance depth of the first photosensitive layer can be adjusted, for example, by changing the type of binder resin, and can also be changed, for example, by adjusting the ratio of the mass of the binder resin to the mass of the first photosensitive layer.

[0151] (strain at break) The breaking strain of the first photosensitive layer is preferably 7.5% or more and 21.0% or less, more preferably 14.0% or more and 21.0% or less. When the breaking strain of the first photosensitive layer is 7.5% or more, the fogging resistance and abrasion resistance of the photosensitive body are improved. When the breaking strain of the first photosensitive layer is 21.0% or less, the fogging resistance of the photosensitive body is improved. The breaking strain of the first photosensitive layer is a value obtained from a stress-strain curve obtained when the first photosensitive layer is pulled at a pulling speed of 5 mm / min using a tensile tester. The breaking strain of the first photosensitive layer is measured, for example, by the method described in the examples below. The breaking strain is adjusted, for example, by changing the type and viscosity average molecular weight of the binder resin.

[0152] (Vickers hardness) The Vickers hardness of the first photosensitive layer is preferably 19.0 HV or more, more preferably 20.0 HV or more. When the Vickers hardness of the first photosensitive layer is 19.0 HV or more, the fogging resistance of the photoreceptor is improved. The upper limit of the Vickers hardness of the first photosensitive layer is not particularly limited, but is, for example, 25.0 HV or less. The Vickers hardness of the first photosensitive layer is measured by a method conforming to JIS (Japanese Industrial Standards) Z2244. The Vickers hardness of the first photosensitive layer is adjusted, for example, by changing the type of binder resin and the type of hole transport agent.

[0153] (Conductive substrate) The conductive substrate is not particularly limited, and at least the surface portion may be made of a material having electrical conductivity. An example of the conductive substrate is a conductive substrate made of a material having electrical conductivity. Another example of the conductive substrate is a conductive substrate coated with a material having electrical conductivity. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Among these conductive materials, aluminum and aluminum alloys are preferred because they have good charge transfer from the photosensitive layer to the conductive substrate.

[0154] The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. The shape of the conductive substrate may be, for example, a sheet or a drum. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[0155] (Middle class) The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used in the intermediate layer. The presence of the intermediate layer makes it possible to maintain an insulating state sufficient to suppress leakage, while facilitating the flow of current generated when the photoreceptor is exposed to light, thereby suppressing an increase in resistance.

[0156] Inorganic particles include, for example, particles of metals (e.g., aluminum, iron, and copper), particles of metal oxides (e.g., titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide), and particles of non-metal oxides (e.g., silica).

[0157] Examples of the resin for the intermediate layer are the same as the examples of other binder resins already described. In order to form the intermediate layer and the photosensitive layer well, it is preferable that the resin for the intermediate layer is different from the binder resin contained in the photosensitive layer. The intermediate layer may contain an additive. Examples of the additive contained in the intermediate layer are the same as the examples of the additive contained in the photosensitive layer.

[0158] (Photoreceptor manufacturing method) As a method for producing a photoreceptor, an example of a method for producing a single-layer type photoreceptor and an example of a method for producing a positively charged multi-layer type photoreceptor will be described.

[0159] The method for producing a single-layer photoreceptor includes, for example, a single-layer photosensitive layer forming step. In the single-layer photosensitive layer forming step, a coating liquid for forming a single-layer photosensitive layer (hereinafter, sometimes referred to as a coating liquid for a single-layer photosensitive layer) is prepared. The coating liquid for a single-layer photosensitive layer is applied onto a conductive substrate. Then, at least a part of the solvent contained in the applied coating liquid for a single-layer photosensitive layer is removed to form a single-layer photosensitive layer. The coating liquid for a single-layer photosensitive layer contains, for example, a charge generating agent, a binder resin (SL), an electron transport agent, a hole transport agent (SL), and a solvent. The coating liquid for a single-layer photosensitive layer is prepared by dissolving or dispersing a charge generating agent, a binder resin (SL), an electron transport agent, and a hole transport agent (SL) in a solvent. The coating liquid for a single-layer photosensitive layer may further contain an additive as necessary.

[0160] The method for producing a positively charged multi-layer photoreceptor includes, for example, a charge transport layer forming step and a charge generation layer forming step.

[0161] In the charge transport layer forming step, the coating liquid for the charge transport layer is applied onto a conductive substrate. Then, at least a part of the solvent contained in the applied coating liquid for the charge transport layer is removed to form a charge transport layer. The coating liquid for the charge transport layer contains a hole transport agent (CT), a binder resin (CT), and a solvent. The coating liquid for the charge transport layer can be prepared by dissolving or dispersing the hole transport agent (CT) and the binder resin (CT) in a solvent. The coating liquid for the charge transport layer may further contain an additive, if necessary.

[0162] In the charge generation layer forming step, the charge generation layer coating liquid is applied onto the charge transport layer. Then, at least a part of the solvent contained in the applied charge generation layer coating liquid is removed to form the charge generation layer. The charge generation layer coating liquid contains, for example, a charge generation agent, a binder resin (CG), an electron transport agent, a hole transport agent (CG), and a solvent. The charge generation layer coating liquid is prepared by dissolving or dispersing the charge generation agent, the binder resin (CG), the electron transport agent, and the hole transport agent (CG) in a solvent. The charge generation layer coating liquid may further contain an additive as necessary.

[0163] The solvent contained in the coating liquid for the single-layer photosensitive layer, the coating liquid for the charge generating layer, and the coating liquid for the charge transport layer (hereinafter, these may be collectively referred to as coating liquids) is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid. Examples of the solvent include alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), dimethylformaldehyde, dimethylformamide, and dimethylsulfoxide.

[0164] The solvent contained in the coating liquid for the charge transport layer is preferably different from the solvent contained in the coating liquid for the charge generation layer, because when the coating liquid for the charge generation layer is applied onto the charge transport layer, it is preferable that the charge transport layer is not dissolved in the solvent of the coating liquid for the charge generation layer.

[0165] The coating liquid is prepared by mixing the respective components and dispersing them in a solvent. For example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used for mixing or dispersing.

[0166] The method for applying the coating liquid is not particularly limited as long as the coating liquid can be uniformly applied, and examples of the coating method include dip coating, spray coating, spin coating, and bar coating.

[0167] Methods for removing at least a part of the solvent contained in the coating liquid include, for example, heating, reducing pressure, or a combination of heating and reducing pressure. More specifically, a method for heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer can be mentioned. The temperature for heat treatment is, for example, 40°C or higher and 150°C or lower. The time for heat treatment is, for example, 3 minutes or higher and 120 minutes or lower.

[0168] The method for producing a photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer, if necessary. The step of forming an intermediate layer and the step of forming a protective layer can be appropriately selected from known methods.

[0169] <Second embodiment: Image forming apparatus> An image forming apparatus according to a second embodiment of the present invention will be described below. A tandem type color image forming apparatus will be described as an example with reference to Fig. 7. Fig. 7 is a cross-sectional view showing an example of an image forming apparatus.

[0170] 7 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing device 54. Hereinafter, when there is no need to distinguish between the image forming units 40a, 40b, 40c, and 40d, each of them will be referred to as an image forming unit 40.

[0171] The image forming unit 40 includes an image carrier 30, a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The image carrier 30 is the photoreceptor of the first embodiment (specifically, the single-layer photoreceptor 1 and the positively charged multilayer photoreceptor 10).

[0172] As already described, the photoconductor of the first embodiment can improve fogging resistance. Therefore, by providing the photoconductor of the first embodiment as the image carrier 30, the image forming apparatus 100 can form an image with less fogging on the recording medium P.

[0173] An image carrier 30 is provided at the center of the image forming unit 40. The image carrier 30 is provided so as to be rotatable in the direction of the arrow (counterclockwise in FIG. 7). A charging device 42, an exposure device 44, a developing device 46, and a transfer device 48 are provided around the image carrier 30 in this order from the upstream side in the rotation direction of the image carrier 30.

[0174] A plurality of color (for example, four colors: black, cyan, magenta, and yellow) toner images are sequentially superimposed on the recording medium P on the transfer belt 50 by each of the image forming units 40a to 40d.

[0175] The charging device 42 positively charges the surface (e.g., the peripheral surface) of the image carrier 30. In both cases where the image carrier 30 is a single-layer type photoreceptor 1 and where the image carrier 30 is a positively charged multi-layer type photoreceptor 10, the surface of the image carrier 30 is positively charged. The charging device 42 is, for example, a charging roller.

[0176] The exposure device 44 irradiates the charged surface of the image carrier 30 with exposure light. That is, the exposure device 44 exposes the charged surface of the image carrier 30. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

[0177] The developing device 46 supplies toner to the surface of the image carrier 30 and develops the electrostatic latent image into a toner image. The developing device 46 (for example, the surface of the developing device 46, more specifically, the peripheral surface of the developing device 46) is in contact with the surface of the image carrier 30. That is, the image forming apparatus 100 employs a contact development method. The developing device 46 is, for example, a developing roller. When the developer is a one-component developer, the developing device 46 supplies toner, which is a one-component developer, to the electrostatic latent image formed on the image carrier 30. When the developer is a two-component developer, the developing device 46 supplies toner, which is a toner and a carrier contained in the two-component developer, to the electrostatic latent image formed on the image carrier 30. In this way, the image carrier 30 carries the toner image.

[0178] The transfer belt 50 conveys the recording medium P between the image carrier 30 and the transfer device 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided rotatably in the direction of the arrow (clockwise in FIG. 7).

[0179] The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image carrier 30 to a receiving body. The receiving body is a recording medium P. When the toner image is transferred, the image carrier 30 is in contact with the recording medium P. That is, the image forming apparatus 100 employs a direct transfer method. The transfer device 48 is, for example, a transfer roller.

[0180] The recording medium P onto which the toner image has been transferred by the transfer device 48 is transported by the transfer belt 50 to the fixing device 54. The fixing device 54 is, for example, a heating roller and / or a pressure roller. The unfixed toner image transferred by the transfer device 48 is heated and / or pressurized by the fixing device 54. The toner image is fixed to the recording medium P by heating and / or pressing the toner image. As a result, an image is formed on the recording medium P.

[0181] Although an example of an image forming apparatus has been described above, the image forming apparatus is not limited to the image forming apparatus 100 already described. Although the image forming apparatus 100 already described is a color image forming apparatus, the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus may have only one image forming unit, for example. Furthermore, although the image forming apparatus 100 already described employs a tandem system, the image forming apparatus may employ, for example, a rotary system. Although the charging roller has been described as an example of the charging device 42, the charging device may be a charging device other than a charging roller (for example, a scorotron charger, a charging brush, or a corotron charger). Although the image forming apparatus 100 already described employs a contact development system, the image forming apparatus may employ a non-contact development system. Although the image forming apparatus 100 already described employs a direct transfer system, the image forming apparatus may employ an intermediate transfer system. When the image forming apparatus employs an intermediate transfer system, the transferred body corresponds to an intermediate transfer belt. In the image forming apparatus, the image forming unit 40 described above does not include a cleaning member, but the image forming unit may further include a cleaning member (e.g., a cleaning blade). In addition, the image forming unit 40 described above does not include a static eliminator, but the image forming unit may further include a static eliminator.

[0182] <Third embodiment: Process cartridge> Next, with continued reference to FIG. 7, an example of a process cartridge according to a third embodiment of the present invention will be described. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes an image carrier 30. The image carrier 30 is the photoreceptor of the first embodiment. As already described, the photoreceptor of the first embodiment can improve fogging resistance. Therefore, by including the photoreceptor of the first embodiment as the image carrier 30, the process cartridge can form an image with less fogging on the recording medium P. In addition to the image carrier 30, the process cartridge further includes at least one selected from the group consisting of a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The process cartridge may further include a cleaning member (not shown) and a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics or the like of the image carrier 30 deteriorates, it is possible to easily and quickly replace the image carrier 30 as well. The process cartridge including the photoconductor of the first embodiment has been described above with reference to FIG. EXAMPLES

[0183] The present invention will be described in more detail below using examples, but the present invention is not limited to the scope of the examples.

[0184] <Preparation of Polyarylate Resins (R-1) to (R-7) and (R-12) to (R-24)> Polyarylate resins (R-1) to (R-7) according to the examples and polyarylate resins (R-12) to (R-24) according to the comparative examples were synthesized by the methods shown below. Hereinafter, "polyarylate resins (R-1) to (R-7) and (R-12) to (R-24)" will be referred to as "resins (R-1) to (R-7) and (R-12) to (R-24)", respectively. The compositions of resins (R-1) to (R-7) and (R-12) to (R-24) are shown in Table 3 below. Resin (R-21) had the same repeating units in the same ratio as the resin used in Example 4 of Patent Document 1 (JP Patent Publication 10-20514 A).

[0185] [Table 3]

[0186] In Table 3, "BisCZ," "BisB," "BisC," "BisZ," "BisCE," "DHPE," "DPEC," "TPC," and "IPC" respectively represent compounds represented by the following formulas (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC), and (IPC) (hereinafter, these may be referred to as compounds (BisCZ), (BisB), (BisC), (BisZ), (BisCE), (DHPE), (DPEC), (TPC), and (IPC), respectively).

[0187] [ka]

[0188] Furthermore, the meanings of the terms in Table 3 are as follows: Monomer: Monomer used in the synthesis of polyarylate resin Resin: Polyarylate resin Bisphenol addition rate: The percentage (unit: %) of the amount of the corresponding bisphenol monomer (unit: mole) to the total amount (unit: mole) of bisphenol monomer added in the synthesis of polyarylate resin Dicarboxylic acid addition rate: The percentage (unit: %) of the amount (unit: mole) of the corresponding dicarboxylic acid monomer to the total amount (unit: mole) of dicarboxylic acid monomer added in the synthesis of polyarylate resin Unit: repeating unit. The repeating units shown in Table 3 are formed from the corresponding monomers shown in Table 3. Unit (BisC): A repeating unit derived from the compound (BisC) Unit (BisZ): A repeating unit derived from the compound (BisZ). Unit (BisCE): A repeating unit derived from the compound (BisCE) Unit (IPC): Repeating unit derived from compound (IPC) DMP: 2,6-dimethylphenol PFH: 1H,1H-perfluoro-1-heptanol -: No corresponding monomer is used

[0189] (Synthesis of resin (R-1)) A three-neck flask equipped with a thermometer, a three-way cock, and a dropping funnel was used as the reaction vessel. The monomer compound (BisCZ) (32.8 mmol), the monomer compound (DHPE) (8.2 mmol), the end terminator 2,6-dimethylphenol (0.413 mmol), sodium hydroxide (98 mmol), and benzyltributylammonium chloride (0.384 mmol) were placed in the reaction vessel. The air in the reaction vessel was replaced with argon gas. Water (300 mL) was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50° C. for 1 hour. The contents of the reaction vessel were cooled to 10° C. to obtain an alkaline aqueous solution SA.

[0190] Next, the dicarboxylic acid dichloride (20.8 mmol) of the monomer compound (DPEC) and the dicarboxylic acid dichloride (11.2 mmol) of the monomer compound (TPC) were dissolved in chloroform (150 mL), thereby obtaining a chloroform solution SB.

[0191] The chloroform solution SB was slowly dropped into the alkaline aqueous solution SA over 110 minutes using a dropping funnel. The contents of the reaction vessel were stirred for 4 hours while controlling the temperature (liquid temperature) of the contents of the reaction vessel to 15±5°C to allow the polymerization reaction to proceed. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decant to obtain an organic layer. Next, ion-exchanged water (400 mL) was added to the Erlenmeyer flask. The obtained organic layer was further added to the Erlenmeyer flask. Chloroform (400 mL) and acetic acid (2 mL) were further added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25°C) for 30 minutes. The upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed using a decant to obtain an organic layer. The obtained organic layer was washed with ion-exchanged water (1 L) using a separating funnel. Washing with ion-exchanged water was repeated five times to obtain a water-washed organic layer. Next, the water-washed organic layer was filtered to obtain a filtrate. The obtained filtrate was slowly dropped into methanol (1 L) to obtain a precipitate. The precipitate was collected by filtration and then vacuum-dried for 12 hours at 70° C. As a result, a resin (R-1) having a viscosity average molecular weight of 56,000 was obtained.

[0192] Resins (R-1) having the viscosity average molecular weights shown in Tables 4 to 8 and Tables 15 to 21 were obtained by the same method as used for synthesizing resin (R-1) having a viscosity average molecular weight of 56,000, except that the amount of end terminator added was changed so that the viscosity average molecular weight of resin (R-1) would be as shown in these tables. Note that the smaller the amount of end terminator added, the larger the viscosity average molecular weight of resin (R-1).

[0193] (Synthesis of Resins (R-2) to (R-7) and (R-12) to (R-24)) Resins (R-2) to (R-7) and (R-12) to (R-24) were each synthesized in the same manner as in the synthesis of resin (R-1), except that the monomers shown in Table 3 were used at the addition rates shown in Table 3. The amount of each bisphenol monomer added was set so that the total amount of bisphenol monomers was 41.0 millimoles and the bisphenol addition rate shown in Table 3 was achieved. For example, in the synthesis of resin (R-5), the amount of compound (BisB) added was 32.8 millimoles (= 41.0 × 80 / 100), and the amount of compound (DHPE) added was 8.2 millimoles (= 41.0 × 20 / 100). The amount of each dicarboxylic acid monomer added was set so that the total amount of dicarboxylic acid monomers was 32.0 millimoles and the dicarboxylic acid addition rate shown in Table 3 was achieved. For example, in the synthesis of resin (R-5), the amount of compound (DPEC) added was 16.0 mmol (=32.0×50 / 100), and the amount of compound (TPC) added was 16.0 mmol (=32.0×50 / 100).

[0194] The obtained resins (R-1) to (R-7) and (R-12) to (R-24) were analyzed using a proton nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., 600 MHz). 1 H-NMR spectrum was measured. Deuterated chloroform was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. As a representative example of resins (R-1) to (R-7) and (R-12) to (R-24), 1 The H-NMR spectrum is shown in FIG. 1 It was confirmed that resin (R-1) was obtained from the chemical shifts read from the H-NMR spectrum. It was also confirmed that resins (R-2) to (R-7) and (R-12) to (R-24) were obtained by the same method.

[0195] <Polycarbonate resins (R-8) to (R-10) and polyarylate resins (R-11)> As binder resins used in the manufacture of a photoreceptor according to a comparative example, polycarbonate resins represented by formulas (R-8) to (R-10) and polyarylate resins represented by formula (R-11) were prepared. Hereinafter, "polycarbonate resins represented by formulas (R-8) to (R-10) and polyarylate resins represented by formula (R-11)" may be referred to as "resins (R-8) to (R-11)", respectively. m1 and m2 in formula (R-10), and n1, n2, n3, and n4 in formula (R-11) each indicate the content (unit: mol%) of the corresponding repeating unit relative to the total number of repeating units contained in the resin. m1 and m2 in formula (R-10) were 50 mol% and 50 mol%, respectively. In the formula (R-11), n1, n2, n3, and n4 were 25 mol%, 25 mol%, 25 mol%, and 25 mol%, respectively. The viscosity average molecular weights of the resins (R-8) to (R-11) were 65,000, 58,000, 51,000, and 55,000, respectively.

[0196] [ka]

[0197] <Manufacturing of single-layer photoreceptor> (Production of single-layer photoreceptor (A-1)) 2 parts by mass of Y-type titanyl phthalocyanine as a charge generating agent, 70 parts by mass of hole transport agent (H-1) as a hole transport agent (SL), 50 parts by mass of electron transport agent (E-1), 100 parts by mass of resin (R-1) (viscosity average molecular weight 35200) as a binder resin (SL), and 500 parts by mass of tetrahydrofuran as a solvent were mixed for 20 minutes using a rod-shaped ultrasonic oscillator to obtain a dispersion. The dispersion was filtered using a filter with a mesh size of 5 μm to obtain a coating liquid for a single-layer type photosensitive layer. The coating liquid for a single-layer type photosensitive layer was applied onto a conductive substrate (aluminum drum-shaped support) by a dip coating method, and dried with hot air at 120° C. for 50 minutes. In this way, a single-layer type photosensitive layer (film thickness 30 μm) was formed on the conductive substrate to obtain a single-layer type photoreceptor (A-1). In the single-layer type photoreceptor (A-1), a single-layer type photosensitive layer was provided directly on the conductive substrate.

[0198] (Production of Single-Layer Photoreceptors (A-2) to (A-70) and (B-1) to (B-25)) Each of the single-layer photoreceptors (A-2) to (A-70) and (B-1) to (B-25) was produced in the same manner as in the production of the single-layer photoreceptor (A-1), except that resins of the types and viscosity average molecular weights shown in Tables 4 to 10 were used in the amounts shown in Tables 4 to 10, hole transport agents of the types shown in Tables 4 to 10 were used in the amounts shown in Tables 4 to 10, and electron transport agents of the types shown in Tables 4 to 10 were used in the amounts shown in Tables 4 to 10.

[0199] <Manufacture of positively charged laminated photoreceptor> (Manufacture of positively charged laminated photoreceptor (C-1)) First, a charge transport layer was formed. In detail, 100 parts by mass of a hole transport agent (H-10) as a hole transport agent (CT), 100 parts by mass of a resin (R-1) (viscosity average molecular weight 62000) as a binder resin (CT), and 500 parts by mass of tetrahydrofuran as a solvent were mixed for 20 minutes using a rod-shaped ultrasonic oscillator to obtain a dispersion liquid. The dispersion liquid was filtered using a filter with an opening of 5 μm to obtain a coating liquid for a charge transport layer. The coating liquid for a charge transport layer was applied onto a conductive substrate (aluminum drum-shaped support) by a dip coating method, and was dried with hot air at 120° C. for 50 minutes. In this way, a charge transport layer (film thickness 15 μm) was formed on the conductive substrate.

[0200] Next, a charge generation layer was formed. In detail, 2 parts by mass of Y-type titanyl phthalocyanine as a charge generation agent, 70 parts by mass of hole transport agent (H-1) as a hole transport agent (CG), 50 parts by mass of electron transport agent (E-1), 100 parts by mass of resin (R-1) (viscosity average molecular weight 35200) as a binder resin (CG), and 500 parts by mass of 1,2-dichloroethane as a solvent were mixed for 20 minutes using a rod-shaped ultrasonic oscillator to obtain a dispersion liquid. The dispersion liquid was filtered using a filter with a mesh size of 5 μm to obtain a coating liquid for a charge generation layer. The coating liquid for a charge generation layer was applied on the formed charge transport layer by a dip coating method, and the coating was dried with hot air at 120° C. for 50 minutes. In this way, a charge generation layer (film thickness 15 μm) was formed on the charge transport layer to obtain a positively charged laminated photoreceptor (C-1). In the positively charged laminated photoreceptor (C-1), a charge transport layer was provided directly on the conductive substrate, and a charge generation layer was provided directly on the charge transport layer.

[0201] (Manufacture of positively charged laminated photoreceptors (C-2) to (C-75) and (D-1) to (D-25)) The positively charged multi-layer photoreceptors (C-2) to (C-75) and (D-1) to (D-25) were each produced in the same manner as in the production of the positively charged multi-layer photoreceptor (C-1), except that a resin of the type and viscosity average molecular weight shown in the "charge transport layer" column of Tables 15 to 21 was used as the binder resin (CT), a resin of the type and viscosity average molecular weight shown in the "charge generation layer" column of Tables 15 to 21 was used in the amount shown in the same column as the binder resin (CT), a hole transport agent of the type shown in the "charge generation layer" column of Tables 15 to 21 was used in the amount shown in the same column as the binder resin (CG), a charge transport agent of the type shown in the "charge generation layer" column of Tables 15 to 21 was used in the amount shown in the same column as the binder resin (CT), a charge transport agent of the type shown in the "charge generation layer" column of Tables 15 to 21 was used in the amount shown in the same column as the binder resin (CG), and a charge generation layer was formed to have a thickness shown in the "charge generation layer" column of Tables 15 to 21. The amounts of binder resin (CT) and hole transport agent (CT) added in the manufacture of the positively charged multilayer photoreceptors (C-2) to (C-75) and (D-1) to (D-25) were the same as those in the manufacture of the positively charged multilayer photoreceptor (C-1). The thickness of the charge generation layer was changed by changing the speed at which the conductive substrate was lifted from the charge generation layer coating liquid when the charge generation layer coating liquid was applied. The faster the lifting speed, the thicker the charge generation layer.

[0202] <Measurement of Viscosity Average Molecular Weight> The viscosity average molecular weight of the resin was measured according to JIS (Japanese Industrial Standards) K7252-1: 2016. The measured viscosity average molecular weights are shown in Tables 4 to 10 and Tables 15 to 21.

[0203] <Film thickness measurement> The film thickness was measured using an eddy current film thickness meter ("LH-373" manufactured by Kett Electric Laboratory Co., Ltd.) The measured film thicknesses are shown in Tables 4 to 10 and Tables 15 to 21.

[0204] <Measurement of scratch resistance depth> The scratch resistance depth was measured using a scratching device 200 specified in JIS K5600-5-5 (Japanese Industrial Standard K5600: General test methods for paints, Part 5: Mechanical properties of coatings, Section 5: Scratch hardness (loading needle method)).

[0205] The object of measurement of the scratch resistance depth is a photoreceptor (single-layer type photoreceptor 1 or positively charged multi-layer type photoreceptor 10). The following describes an example in which the object of measurement is the single-layer type photoreceptor 1. When the object of measurement is the positively charged multi-layer type photoreceptor 10, the scratch resistance depth can be measured in the same manner as in the measurement of the single-layer type photoreceptor 1, except that the single-layer type photoreceptor 1 is changed to the positively charged multi-layer type photoreceptor 10.

[0206] First, the scratching device 200 will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of the configuration of the scratching device 200. The scratching device 200 includes a fixed base 201, a fixture 202, a scratching needle 203, a support arm 204, two shaft support parts 205, a base 206, two rail parts 207, a weight plate 208, and a constant-speed motor (not shown).

[0207] 9, the X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The X-axis direction indicates the longitudinal direction of the fixed base 201. The Y-axis direction indicates a direction perpendicular to the X-axis direction in a plane parallel to the upper surface 201a (mounting surface) of the fixed base 201. The X-axis, Y-axis, and Z-axis directions in FIGS. 10 to 12 described later have the same meanings as those in FIG. 9.

[0208] The fixing base 201 corresponds to the test plate fixing base in JIS (Japanese Industrial Standards) K5600-5-5. The fixing base 201 has an upper surface 201a, one end 201b, and the other end 201c. The one end 201b faces two shaft supports 205.

[0209] Fixture 202 is provided on the other end 201c side of upper surface 201a of fixing base 201. Fixture 202 fixes a measurement target (single-layer type photoreceptor 1 or positively charged multi-layer type photoreceptor 10) to upper surface 201a of fixing base 201. Upper surface 201a of fixing base 201 is a horizontal plane.

[0210] The scratching needle 203 has a tip 203b (see FIG. 10). The tip 203b has a hemispherical structure with a diameter of 1 mm. The material of the tip 203b is sapphire.

[0211] The support arm 204 supports the scratching needle 203. The support arm 204 rotates about a support shaft 204a in a direction in which the scratching needle 203 approaches the single-layer photoreceptor 1 and in a direction in which the scratching needle 203 moves away from the single-layer photoreceptor 1.

[0212] The two shaft support portions 205 rotatably support the support arm portion 204 .

[0213] The base 206 has an upper surface 206a. Two shaft supports 205 are provided on one end side of the upper surface 206a.

[0214] The two rail portions 207 are provided on the other end side of the upper surface 206a. The two rail portions 207 are provided parallel to each other and facing each other. The two rail portions 207 are each provided parallel to the longitudinal direction (X-axis direction) of the fixed base 201. The fixed base 201 is attached between the two rail portions 207. The fixed base 201 is horizontally movable along the rail portions 207 in the longitudinal direction (X-axis direction) of the fixed base 201.

[0215] The weight plate 208 is provided on the scratching needle 203 via the support arm 204. A weight 209 is placed on the weight plate 208.

[0216] The constant speed motor moves the fixed base 201 in the longitudinal direction (X-axis direction) along the rail portion 207 .

[0217] The method for measuring the scratch resistance depth is described below. The method for measuring the scratch resistance depth included a first step, a second step, a third step, and a fourth step. The scratch resistance depth was measured using a scratching device 200 specified in JIS (Japanese Industrial Standards) K5600-5-5. A surface property measuring instrument ("HEIDON TYPE14" manufactured by Shinto Scientific Co., Ltd.) was used as the scratching device 200. The measurement of the scratch resistance depth was performed in an environment with a temperature of 23°C and a relative humidity of 50% RH. The photoconductor had a drum (cylindrical) shape. By adopting the following method for measuring the scratch depth, it was possible to accurately measure the characteristics of the photosensitive layer that affect the occurrence of fog in the formed image.

[0218] (First Step) In the first step, the single-layer photoreceptor 1 was fixed to the upper surface 201a of the fixing base 201 so that the longitudinal direction of the single-layer photoreceptor 1 was parallel to the longitudinal direction of the fixing base 201. 2 The (rotation axis) direction corresponded to the longitudinal direction of the single-layer photoreceptor 1. When the single-layer photoreceptor 1 is in a sheet form, the long side direction of the single-layer photoreceptor 1 corresponds to the longitudinal direction of the single-layer photoreceptor 1.

[0219] (Second step) In the second step, the scratch needle 203 was brought into vertical contact with the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1. A method for bringing the scratch needle 203 into vertical contact with the surface 3a of the photosensitive layer 3 of the drum-shaped single-layer photoreceptor 1 will be described with reference to Figs. 10 and 11 in addition to Fig. 9. Fig. 10 is a cross-sectional view taken along line XX shown in Fig. 9. Fig. 10 is a cross-sectional view of the scratch needle 203 brought into contact with the single-layer photoreceptor 1. Fig. 11 is a side view of the fixed base 201, the scratch needle 203, and the single-layer photoreceptor 1 shown in Fig. 9.

[0220] Center axis A of the scratching needle 203 1 The scratching needle 203 was brought close to the single-layer photoreceptor 1 so that the extension line of the scratching needle 203 was perpendicular to the upper surface 201a of the fixed base 201. Then, the tip 203b of the scratching needle 203 was abutted against the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1 at a point furthest from the upper surface 201a of the fixed base 201 in the vertical direction (Z-axis direction). As a result, the tip 203b of the scratching needle 203 was brought into contact with the abutment point P 3 The scratch needle 203 abutted against the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1. 1 is the tangent A 2 The tip 203b of the scratch needle 203 was brought into contact with the single-layer photoconductor 1 so as to be perpendicular to the tangent line A. 2 is the central axis L of the single-layer photoconductor 1. 2 The contact point P of the outer circumference formed by the cross section of the single-layer photoconductor 1 perpendicular to 3As a result, the scratch needle 203 is brought into contact perpendicularly with the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1. When the single-layer photoreceptor 1 is in the form of a sheet, the central axis A of the scratch needle 203 is aligned parallel to the surface 3a (plane) of the photosensitive layer 3 of the single-layer photoreceptor 1. 1 The scratch needle 203 is brought into contact with the surface 3a of the photosensitive layer 3 so that the extension line of the scratch needle 203 is vertical.

[0221] When the scratching needle 203 was brought into contact with the base 201 by the above method, the positional relationship between the fixed base 201, the single-layer photoconductor 1, and the scratching needle 203 was as follows. 1 and the central axis L of the single-layer photoconductor 1 2 and the intersection point P 2 The photosensitive layer 3 and the upper surface 201a intersect perpendicularly at the contact point P 1 and the intersection point P 2 and the contact point P of the photosensitive layer 3 and the tip 203b of the scratch needle 203. 3 and the central axis A of the scratching needle 203 1 The scratch needle 203 was located on the extension of the central axis A 1 The extension line of the line A is the upper surface 201a of the fixed base 201. 2 were perpendicular to each other.

[0222] (Third Step) In the third step, a load W of 10 g was applied from the scratching needle 203 to the photosensitive layer 3 with the scratching needle 203 in vertical contact with the surface 3a of the photosensitive layer 3. Specifically, a weight 209 of 10 g was placed on the weight plate 208. In this state, the fixed base 201 was moved. Specifically, the constant speed motor was driven to move the fixed base 201 horizontally in the longitudinal direction (X-axis direction) along the rail portion 207. That is, one end 201b of the fixed base 201 was brought to a first position N 1 From the second position N 2 The second position N 2 is the first position N 13. The fixed table 201 was located downstream in the longitudinal direction of the fixed table 201, in the direction in which the fixed table 201 moves away from the two shaft support portions 205. As the fixed table 201 moved in the longitudinal direction, the single-layer photoreceptor 1 also moved horizontally in the longitudinal direction of the fixed table 201. The moving speed of the fixed table 201 and the single-layer photoreceptor 1 was 30 mm / min. The moving distance of the fixed table 201 and the single-layer photoreceptor 1 was 30 mm. The moving distance of the fixed table 201 and the single-layer photoreceptor 1 from the first position N 1 and second position N 2 Distance D between 1-2 As a result of the movement of the fixed base 201 and the single-layer photoreceptor 1, a scratch S was formed on the surface 3a of the photosensitive layer 3 of the single-layer photoreceptor 1 by the scratching needle 203. The scratch S will be described with reference to FIG. 12 in addition to FIGS. 9 to 11. FIG. 12 shows the scratch S formed on the surface 3a of the photosensitive layer 3. The scratch S is formed on the upper surface 201a of the fixed base 201 and the tangent line A 2 The scratch S was formed perpendicular to the line L shown in FIG. 3 The line L 3 is multiple contact points P 3 Line L is a line composed of 3 is the upper surface 201a of the fixing base 201 and the central axis L of the single-layer photoconductor 1. 2 The lines L 3 is the central axis A of the scratching needle 203 1 was perpendicular to

[0223] (Fourth step) In the fourth step, the maximum depth Ds of the scratch S is max The scratch resistance depth, which is the depth at which the scratch is resistant to the scratch, was measured. Specifically, the single-layer photoreceptor 1 was removed from the fixing stand 201. Using a three-dimensional interference microscope (Bruker's "WYKO NT-1100"), the scratch S formed on the photosensitive layer 3 of the single-layer photoreceptor 1 was observed at a magnification of 5 times, and the depth Ds of the scratch S was measured. The depth Ds of the scratch S is the depth of the tangent A 2 The maximum depth Ds of the scratch S was the distance from the depth Ds to the valley of the scratch S. maxThe measured scratch resistance depth (unit: μm) is shown in Tables 4 to 10 and Tables 15 to 21.

[0224] <Measurement of strain at break> Among the manufactured single-layer photoreceptors and positively charged multi-layer photoreceptors, the breakage strain of the first photosensitive layer was measured for the single-layer photoreceptor shown in Table 11 and the positively charged multi-layer photoreceptor shown in Table 22 as representative examples. In detail, the first photosensitive layer was peeled off from the conductive substrate of the photoreceptor (single-layer photoreceptor and positively charged multi-layer photoreceptor). Then, the first photosensitive layer was cut into a size of 3 mm in width and 30 mm in length to obtain a sample. Then, the sample was attached to a tensile tester (Shimadzu Corporation "Autograph (registered trademark) AGS-J 5kN"). When attaching the sample, the distance between the grips of the tensile tester was adjusted to 8 mm. Then, the sample was pulled at a pulling speed of 5 mm / min under an environment of a temperature of 23°C and a humidity of 50% RH to obtain a stress-strain curve. The breakage strain was obtained from the obtained stress-strain curve. The measured breakage strains are shown in Tables 11 and 22.

[0225] <Vickers hardness measurement> Among the manufactured single-layer photoreceptors and positively charged multi-layer photoreceptors, the Vickers hardness of the first photosensitive layer was measured for the single-layer photoreceptor shown in Table 12 and the positively charged multi-layer photoreceptor shown in Table 23 as representative examples. In detail, the Vickers hardness of the first photosensitive layer was measured by a method conforming to JIS (Japanese Industrial Standards) Z2244. A hardness tester (Micro Vickers Hardness Tester DMH-1 type manufactured by Matsuzawa Co., Ltd. (formerly Matsuzawa Seiki Co., Ltd.)) was used to measure the Vickers hardness. The Vickers hardness was measured under the following conditions: temperature 23°C, diamond indenter load (test force) 10gf, time required to reach test force 5 seconds, diamond indenter approach speed 2mm / sec, and test force retention time 1 second. The measured Vickers hardness is shown in Tables 12 and 23.

[0226] <Evaluation> A modified monochrome printer (Kyocera Document Solutions Inc.'s "ECOSYS (registered trademark) P2040dw") was used as an evaluation machine for evaluating fogging resistance and abrasion resistance. This evaluation machine was equipped with a charging roller as a charging device. This evaluation machine also adopted a contact development method and a direct transfer method. This evaluation machine also did not have a cleaning blade. The paper used for the evaluation was "Kyocera Document Solutions Brand Paper VM-A4" (A4 size) sold by Kyocera Document Solutions Inc. The developer used for the evaluation was a one-component developer (prototype). The evaluation machine was set under the conditions that the rotation speed of the photoconductor (specifically, the single-layer photoconductor and the positively charged laminated photoconductor) was 240 mm / sec, and the charging potential of the photoconductor was +600 V.

[0227] (Evaluation of fogging resistance) The fogging resistance of the manufactured single-layer photoreceptor and positively charged multi-layer photoreceptor was evaluated. The fogging resistance was evaluated under an environment of 32.5°C temperature and 80% RH relative humidity. Using the evaluation machine, images with a printing rate of 1% were continuously printed on 12,000 sheets of paper. Then, a blank image was printed on one sheet of paper. Using a reflection densitometer (X-rite's "RD914"), the reflection density was measured at three points in the blank image on the printed paper, and the arithmetic average value was taken as the reflection density A. In addition, the reflection density was measured at three points on a sheet of paper on which no printing was performed, and the arithmetic average value was taken as the reflection density B. Then, the fogging density (FD) was calculated based on the formula "FD = reflection density A - reflection density B". From the calculated FD, the fogging resistance was evaluated according to the following criteria. The FD and the evaluation results are shown in Tables 4 to 10 and Tables 15 to 21. Photoconductors that received ratings of A, B, and C were evaluated as having good fogging resistance, and photoconductors that received a rating of D were evaluated as having poor fogging resistance.

[0228] (Criteria for evaluating fogging resistance) Judgment A: FD is 0.010 or less. Judgment B: FD is greater than 0.010 and less than or equal to 0.020. Judgment C: FD is greater than 0.020 and less than 0.045. Judgment D (poor): FD is 0.045 or more.

[0229] (Evaluation of wear resistance) Among the manufactured single-layer photoreceptors and positively charged multi-layer photoreceptors, the single-layer photoreceptor shown in Table 13 and the positively charged multi-layer photoreceptor shown in Table 24 were evaluated for wear resistance as representative examples. The wear resistance evaluation was performed under an environment of 23°C temperature and 50% RH relative humidity. The film thickness T1 of the first photosensitive layer was measured. Next, the photoreceptor was mounted on an evaluation machine. Using the evaluation machine, images with a print rate of 1% were continuously printed on 15,000 sheets of paper. After printing, the film thickness T2 of the first photosensitive layer was measured. The film thicknesses T1 and T2 were measured by the method described in <Measurement of film thickness> above. Then, the wear amount (unit: μm) of the first photosensitive layer was calculated from the formula "wear amount = T1 - T2". The calculated wear amounts are shown in Tables 13 and 24. The smaller the wear amount, the better the wear resistance of the photoreceptor. If the wear amount is 6.0 μm or less, it is determined that the photoreceptor has sufficient wear resistance for practical use.

[0230] (Evaluation of sensitivity characteristics) Of the manufactured single-layer photoreceptors and positively charged multi-layer photoreceptors, the single-layer photoreceptor shown in Table 14 and the positively charged multi-layer photoreceptor shown in Table 25 were used as representative examples to evaluate their sensitivity characteristics. The sensitivity characteristics of the photoreceptors were evaluated using a drum sensitivity tester (manufactured by Gentec Co., Ltd.) in an environment of 23°C temperature and 50% RH relative humidity. In detail, the photoreceptor was charged using the drum sensitivity tester so that the surface potential of the photoreceptor was +600V. Next, the surface of the photoreceptor was irradiated with monochromatic light (wavelength: 780 nm, half-width: 20 nm, light energy: 1.0 μJ / cm) extracted from the light of a halogen lamp using a bandpass filter. The surface potential of the photoreceptor was measured 0.5 seconds after irradiation with the monochromatic light, and the post-exposure potential (V L The post-exposure potential of each photoconductor is shown in Tables 14 and 25. The smaller the post-exposure potential, the better the sensitivity characteristics of the photoconductor. If the post-exposure potential is +135V or less, it is considered that the sensitivity characteristics are sufficient for practical use.

[0231] Tables 4 to 25 are shown below. The meanings of the terms used in Tables 4 to 25 are as follows. ·Molecular weight: viscosity average molecular weight Ratio: Ratio of the mass of the binder resin to the mass of the first photosensitive layer -Fogging: Evaluation of fogging resistance FD: Fog density Coating solution preparation impossible: The resin did not dissolve in the solvent used to prepare the coating solution, and the coating solution could not be prepared. - Unmeasurable: The resin did not dissolve in the solvent used to measure viscosity and molecular weight, so the viscosity average molecular weight could not be measured. Hardness: Vickers hardness ·V L : Potential after exposure

[0232] [Table 4]

[0233] [Table 5]

[0234] [Table 6]

[0235] [Table 7]

[0236] [Table 8]

[0237] [Table 9]

[0238] [Table 10]

[0239]

Table 11

[0240]

Table 12

[0241]

Table 13

[0242]

Table 14

[0243]

Table 15

[0244]

Table 16

[0245]

Table 17

[0246]

Table 18

[0247]

Table 19

[0248]

Table 20

[0249]

Table 21

[0250]

Table 22

[0251]

Table 23

[0252]

Table 24

[0253]

Table 25

[0254] As can be seen from the formulas (R-8) to (R-11), the resins (R-8) to (R-11) were not included in the polyarylate resin (PA). As can be seen from Table 3, the resins (R-12) to (R-24) were not included in the polyarylate resin (PA). For this reason, as shown in Table 10, the resins (R-12), (R-14), (R-16), (R-21), and (R-24) were not dissolved in the solvent for preparing the coating solution for the single-layer photosensitive layer, and the coating solution for the single-layer photosensitive layer could not be prepared, and the photosensitive layer (more specifically, the single-layer photosensitive layer) could not be formed. In addition, as shown in Tables 9 and 10, the fogging resistance of the single-layer photoreceptors (B-1) to (B-12), (B-14), (B-16), (B-18) to (B-21), and (B-23) to (B-24) having a single-layer photosensitive layer containing the resins (R-8) to (R-11), (R-13), (R-15), (R-17) to (R-20), and (R-22) to (R-23) was poor. In addition, as shown in Table 21, the resins (R-12), (R-14), (R-16), (R-21), and (R-24) were not dissolved in the solvent for preparing the coating liquid for the charge generation layer, and the coating liquid for the charge generation layer could not be prepared, and the photosensitive layer (more specifically, the charge generation layer) could not be formed. Furthermore, as shown in Tables 20 and 21, the fogging resistance of the positively charged multilayer photoreceptors (D-1) to (D-12), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24) having charge generating layers containing the resins (R-8) to (R-11), (R-13), (R-15), (R-17) to (R-20), and (R-22) to (R-23) was poor.

[0255] On the other hand, as can be seen from Table 3, the resins (R-1) to (R-7) were resins included in the polyarylate resin (PA). Therefore, as shown in Tables 4 to 8, the fogging resistance of the single-layer photoreceptors (A-1) to (A-70) having a single-layer photosensitive layer containing the resins (R-1) to (R-7) was good. In addition, as shown in Tables 15 to 19, the fogging resistance of the positively charged multilayer photoreceptors (C-1) to (C-75) having a charge generating layer containing the resins (R-1) to (R-7) was good.

[0256] As shown in Table 11, the breaking strain of the single-layer photosensitive layer of the single-layer photosensitive member (A-21) was less than 7.5%. As shown in Table 13, the wear amounts of the single-layer photosensitive members (A-1) to (A-20) and (A-22) were smaller than that of the single-layer photosensitive member (A-21). As shown in Table 22, the breaking strain of the charge generating layer of the positively charged laminated photosensitive member (C-21) was less than 7.5%. As shown in Table 22, the wear amounts of the single-layer photosensitive members (C-1) to (C-20) and (C-22) were smaller than that of the single-layer photosensitive member (A-21). Therefore, a photosensitive member having a breaking strain of the first photosensitive layer (single-layer photosensitive layer and charge generating layer) of 7.5% or more is judged to be excellent in wear resistance as well as fogging resistance.

[0257] As shown in Table 11, the break strain of the single-layer photosensitive layer of the single-layer photosensitive member (A-22) exceeded 21.0%. As shown in Table 5, the fogging resistance of the single-layer photosensitive member (A-22) was judged to be B. As shown in Table 22, the break strain of the charge generating layer of the positively charged multi-layer photosensitive member (C-22) exceeded 21.0%. As shown in Table 16, the fogging resistance of the positively charged multi-layer photosensitive member (C-22) was judged to be B. It is considered that the fogging resistance of the photosensitive member can be further improved than that of the judgement B by the break strain of the first photosensitive layer (single-layer photosensitive layer and charge generating layer) being 21.0% or less.

[0258] As shown in Table 12, the Vickers hardness of the single-layer photoreceptors (A-14) to (A-19), (A-52) to (A-67), and (A-70) was 19.0 HV or more. The Vickers hardness of the single-layer photoreceptors (B-5) to (B-8), (B-14), (B-16), (B-18) to (B-21), and (B-23) to (B-24) was less than 19.0 HV. As shown in Tables 4 to 10, the fogging resistance of the single-layer photoreceptors (A-14) to (A-19), (A-52) to (A-67), and (A-70) was superior to that of the single-layer photoreceptors (B-5) to (B-8), (B-14), (B-16), (B-18) to (B-21), and (B-23) to (B-24). As shown in Table 23, the Vickers hardness of the positively charged multilayer photoreceptors (C-52) to (C-75) was 19.0 HV or more. The Vickers hardness of the positively charged multilayer photoreceptors (D-5) to (D-8), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24) was less than 19.0 HV. As shown in Tables 15 to 21, the fogging resistance of the positively charged multi-layer photoreceptors (C-52) to (C-75) was superior to that of the positively charged multi-layer photoreceptors (D-5) to (D-8), (D-14), (D-16), (D-18) to (D-21), and (D-23) to (D-24). Therefore, it is considered that the fogging resistance of the photoreceptor is further improved by having the Vickers hardness of the first photosensitive layer (single-layer photosensitive layer and charge generating layer) of 19.0 HV or more.

[0259] As shown in Table 7, the single-layer photoreceptor (A-49) contained a hole transport agent (SL) represented by the formula (25) (H-11). As shown in Table 14, the post-exposure potential of the single-layer photoreceptor (A-49) exceeded +130V. As shown in Tables 5 to 7, the single-layer photoreceptors (A-23) to (A-48) and (A-50) contained a hole transport agent represented by the formula (20), (21), (22), (23), or (24). As shown in Table 14, the post-exposure potential of the single-layer photoreceptors (A-23) to (A-48) and (A-50) was +130 or less. As shown in Table 18, the positively charged multi-layer photoconductor (C-49) contained a hole transport agent (CG) represented by the formula (H-11) represented by formula (25). As shown in Table 25, the potential after exposure of the positively charged multi-layer photoconductor (C-49) exceeded +130V. As shown in Tables 16 to 18, the positively charged multi-layer photoconductors (C-23) to (C-48) and (C-50) contained a hole transport agent represented by the formula (20), (21), (22), (23), or (24). As shown in Table 25, the potential after exposure of the positively charged multi-layer photoconductors (C-23) to (C-48) and (C-50) was +130 or less. Therefore, it is considered that the inclusion of the hole transport agent (20), (21), (22), (23), or (24) in the first photosensitive layer (single-layer type photosensitive layer and charge generating layer) improves the sensitivity characteristics of the photosensitive layer as well as the fogging resistance of the photosensitive layer.

[0260] As shown in Table 7, the mass ratio of the binder resin (SL) of the single-layer photoreceptor (A-51) was more than 0.50 with respect to the mass of the single-layer photosensitive layer. As shown in Table 14, the post-exposure potential of the single-layer photoreceptor (A-51) exceeded +130V. As shown in Tables 5 to 7, the mass ratio of the binder resin (SL) of the single-layer photoreceptors (A-23) to (A-48) and (A-50) was 0.50 or less with respect to the mass of the single-layer photosensitive layer. As shown in Table 14, the post-exposure potential of the single-layer photoreceptors (A-23) to (A-48) and (A-50) was +130 or less. As shown in Table 18, the mass ratio of the binder resin (CG) of the positively charged laminated photoreceptor (C-51) was more than 0.50 with respect to the mass of the charge generating layer. As shown in Table 25, the post-exposure potential of the positively charged multi-layer photoreceptor (C-51) exceeded +130V. As shown in Tables 16 to 18, the mass ratio of the binder resin (CG) of the positively charged multi-layer photoreceptors (C-23) to (C-48) and (C-50) was 0.50 or less relative to the mass of the charge generating layer. As shown in Table 25, the post-exposure potential of the positively charged multi-layer photoreceptors (C-23) to (C-48) and (C-50) was +130 or less. Therefore, it is determined that when the mass ratio of the binder resin (specifically, the binder resin (SL) or (CG)) is 0.50 or less relative to the mass of the first photosensitive layer (specifically, the single-layer photosensitive layer or the charge generating layer), in addition to the fogging resistance of the photoreceptor, the sensitivity characteristics of the photoreceptor are improved.

[0261] From the above, it has been shown that the photoconductors of the present invention, including the single-layer type photoconductors (A-1) to (A-70) and the positively charged multi-layer type photoconductors (C-1) to (C-75), can form a photosensitive layer well and have excellent fogging resistance. It is also judged that the process cartridge and image forming apparatus of the present invention equipped with such photoconductors can form images with less fogging on a recording medium. [Industrial Applicability]

[0262] The photoconductor and the process cartridge according to the present invention can be used in an image forming apparatus, and the image forming apparatus according to the present invention can be used to form an image on a recording medium. [Explanation of symbols]

[0263] 1: Single-layer photoconductor (electrophotographic photoconductor) 2: Conductive substrate 3: Photosensitive layer 3s: Single-layer photosensitive layer 10: Positively charged laminated photoconductor (electrophotographic photoconductor) 11: Charge transport layer 12: Charge generating layer 30: Image carrier 42: Charging device 44: Exposure equipment 46: Developing device 48: Transcription device 100: Image forming apparatus P: Recording medium

Claims

1. A conductive substrate and at least one photosensitive layer are provided. The at least one photosensitive layer includes a first photosensitive layer, and the first photosensitive layer is provided on the outermost surface side of the at least one photosensitive layer; the first photosensitive layer contains a charge generating material, a binder resin, an electron transport material, and a hole transport material; The binder resin includes a polyarylate resin, The polyarylate resin has repeating units represented by formulas (1), (2), (3), and (4), a third content, which is the content of the repeating unit represented by the formula (3) relative to the total number of repeating units represented by the formulas (1) and (3), is greater than 0% and less than 50%, a fourth content, which is a content of the repeating unit represented by the formula (4) relative to the total number of the repeating units represented by the formulas (2) and (4), is 35% or more and less than 70%, The electron transport material comprises a compound represented by formula (11), (12), (13), (14), (15), (16), or (17). 【Chemistry 1】 (In the above formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), or R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2). 【Chemistry 2】 (In the formulas (X1) and (X2), * represents a bond.) 【Chemistry 3】 (Q in the above formula (11) 1 and Q. 2 , Q in the formula (12) 21 , Q 22 , Q 23 , and Q 24 , Q in the formula (13) 31 and Q. 32 , Q in the formula (14) 41 , Q 42 , and Q 43 , Q in the formula (15) 51 , Q 52 , Q 53 , and Q 54 , Q in the formula (16) 61 and Q. 62 and Q in the formula (17) 71 , Q 72 , Q 73 , Q 74 , Q 75 , and Q 76 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom; Y in the formula (17) 1 and Y 2 each independently represents an oxygen atom or a sulfur atom.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the polyarylate resin has a viscosity average molecular weight of 35,000 or more and 80,000 or less.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein a ratio of a mass of the binder resin to a mass of the first photosensitive layer is 0.35 or more and 0.50 or less.

4. 4. The electrophotographic photoreceptor according to claim 1, wherein the first photosensitive layer has a scratch resistance depth of 0.50 μm or less.

5. 5. The electrophotographic photoreceptor according to claim 1, wherein the first photosensitive layer has a breaking strain of 7.5% or more and 21.0% or less.

6. 6. The electrophotographic photoreceptor according to claim 1, wherein the first photosensitive layer has a Vickers hardness of 19.0 HV or more.

7. In the formula (1), R 1 and R 2 7. The electrophotographic photoreceptor according to claim 1, wherein X represents a divalent group represented by formula (X1).

8. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), The electrophotographic photoreceptor according to claim 1 , wherein the fourth content is equal to or greater than 40% and less than 70%.

9. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), The electrophotographic photoreceptor according to claim 1 , wherein the third content is equal to or greater than 30% and less than 50%.

10. In the formula (1), R 1 and R 2 represents a methyl group, and X represents a divalent group represented by formula (X1), 10. The electrophotographic photoreceptor according to claim 1, wherein the polyarylate resin further has a terminal group having a halogen atom.

11. In the formula (1), R 1 and R 2 represents a hydrogen atom, and X represents a divalent group represented by formula (X2), The electrophotographic photoreceptor according to claim 1 , wherein the fourth content is equal to or greater than 35% and equal to or less than 45%.

12. a content of the repeating unit represented by the formula (1) relative to the total number of the repeating units represented by the formulas (1) and (3) is a first content; a content of the repeating unit represented by the formula (2) relative to the total number of the repeating units represented by the formulas (2) and (4) is a second content; the first content rate is a value different from the second content rate and a value different from the fourth content rate, 12. The electrophotographic photoreceptor according to claim 1, wherein the third content is a value different from the second content and a value different from the fourth content.

13. The electrophotographic photoreceptor according to any one of claims 1 to 12, wherein the third content is greater than 30% and less than 50%.

14. The electrophotographic photoreceptor according to any one of claims 1 to 13, wherein the polyarylate resin does not have a repeating unit represented by formula (5). 【Chemistry 4】

15. The electrophotographic photoreceptor according to any one of claims 1 to 14, wherein the electron transport agent is a compound represented by formula (E-1), (E-2), (E-3), (E-4), (E-5), (E-6), (E-7), (E-8), or (E-9). 【Chemistry 5】

16. The electrophotographic photoreceptor according to any one of claims 1 to 15, wherein the hole transport agent comprises a compound represented by formula (20), (21), (22), (23), (24), or (25). 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】 (In the formula (20), R 16 , R 17 , R 18 , and R 19 each independently represents an alkyl group having 1 to 6 carbon atoms; a6, a7, a8, and a9 each independently represent an integer of 0 to 5; In the formula (21), R 21 , R 22 , and R 23 each independently represents an alkyl group having 1 to 6 carbon atoms; R 24 , R 25 , and R 26 each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms; 1 , b 2 , and b 3 Each independently represents 0 or 1; b 4 , b 5 , and b 6 each independently represents an integer of 0 to 5, In the formula (22), R 31 , R 32 , and R 33 each independently represents an alkyl group having 1 to 6 carbon atoms; R 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom; d 1 , d 2 , and d 3 each independently represents an integer of 0 to 5, In the formula (23), R 50 and R 51 each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group; R 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58 each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having from 1 to 6 carbon atoms; 1 and f 2 Each independently represents an integer of 0 to 2; 3 and f 4 each independently represents an integer of 0 to 5, In the formula (24), R 61 , R 62 , R 63 , R 64 , R 65 , and R 66 each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group; R 67 and R 68 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group; e1, e2, e3, and e4 each independently represent an integer of 0 to 5; e5 and e6 each independently represent an integer of 0 to 4; and e7 and e8 each independently represent 0 or 1; In the formula (25), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms; g1, g2, g4, and g5 each independently represent an integer of 0 to 5; and g3 and g6 each independently represent an integer of 0 to 4.

17. The electrophotographic photoreceptor according to claim 16, wherein the hole transport agent comprises a compound represented by formula (20), (21), (22), (23), or (24).

18. The electrophotographic photoreceptor according to any one of claims 1 to 16, wherein the hole transport agent comprises a compound represented by formula (H-1), (H-2), (H-3), (H-4), (H-5), (H-6), (H-7), (H-8), (H-9), (H-10), or (H-11). 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】

19. The electrophotographic photoreceptor according to any one of claims 1 to 18, wherein the photosensitive layer is a single-layer type photosensitive layer that is the first photosensitive layer.

20. The electrophotographic photoreceptor according to any one of claims 1 to 18, wherein the photosensitive layer is a two-layer structure, and the two photosensitive layers are a charge generating layer which is the first photosensitive layer, and a charge transport layer which is the second photosensitive layer.

21. At least one selected from the group consisting of a charging device, an exposure device, a developing device, and a transfer device; A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 20.

22. An image carrier; a charging device for charging the surface of the image carrier to a positive polarity; an exposure device that exposes the charged surface of the image carrier to light to form an electrostatic latent image on the surface of the image carrier; a developing device that supplies toner to the surface of the image carrier to develop the electrostatic latent image into a toner image; a transfer device that transfers the toner image from the image carrier to a transfer medium, An image forming apparatus, wherein the image bearing member is the electrophotographic photoreceptor according to any one of claims 1 to 20.

23. The transfer medium is a recording medium, 23. The image forming apparatus according to claim 22, wherein the image carrier is in contact with the recording medium when the toner image is transferred.

24. 24. The image forming apparatus according to claim 22, wherein the developing device is in contact with the surface of the image carrier.

25. 25. The image forming apparatus according to claim 22, wherein the charging device is a charging roller.

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