Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor, process cartridge, and image forming apparatus with excellent electrical properties. [Solution] The electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The photosensitive layer is provided on the conductive substrate. The photosensitive layer contains a substrate, a charge generating agent, a dispersion aid, a hole transporter, and an electron transporter. The substrate is a polyarate resin having repeating units represented by formulas (1), (2), (3), and (4), wherein the content of the repeating units 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 20%. The charge generating agent is titanylphthalocyanine. The dispersion aid is a compound represented by formula (5) or (6). The hole transporter is a compound represented by formula (7) or (8).

Description

[Technical Field]

[0001] This technology relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus used in electrophotographic printing. [Background technology]

[0002] Electrophotographic photoreceptors are used as image carriers in electrophotographic image forming devices such as printers. An electrophotographic photoreceptor has a photosensitive layer laminated on a conductive substrate, with the photosensitive layer comprising a functional material dispersed in a thermoplastic binder resin. The surface of the photoreceptor is used in a pre-charged state (positive or negative), and when the surface is exposed, the charge in the exposed area decreases. When toner charged with the same polarity as the surface is supplied to the photoreceptor, the toner adheres only to the exposed area, forming a toner image. This toner image is transferred to a printing object such as printing paper, and printing is performed.

[0003] In electrophotographic image forming apparatuses, printing is performed by controlling the charge on the surface of the photoreceptor, as described above. Therefore, the electrical characteristics of the electrophotographic photoreceptor are important for printing performance. For example, Patent Documents 1 and 2 disclose electrophotographic photoreceptors that suppress transfer memory (uneven charge on the surface of the photoreceptor). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-181418 [Patent Document 2] Japanese Patent Publication No. 2022-181419 [Overview of the project] [Problems that the invention aims to solve]

[0005] The inventors further investigated the configuration of the photosensitive layer in electrophotographic photoreceptors and found a configuration that enables the realization of an electrophotographic photoreceptor with excellent electrical properties such as charge potential, charge stability, and transfer memory suppression.

[0006] In light of the above circumstances, the objective of this technology is to provide an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus that have excellent electrical properties. [Means for solving the problem]

[0007] To achieve the above objective, an electrophotographic photoreceptor according to one embodiment of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer is provided on the conductive substrate. Furthermore, the photosensitive layer contains a substrate, a charge generating agent, a dispersion aid, a hole transporter, and an electron transporter, wherein the substrate is a polyarate resin having repeating units represented by the following formulas (1), (2), (3), and (4), and the content of the repeating units 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 20%. The charge generating agent is titanylphthalocyanine. The aforementioned dispersing agent consists of a compound represented by the following formula (5) or formula (6): The hole transporter consists of a compound represented by the following formula (7) or formula (8).

[0008] [ka]

[0009] [ka]

[0010] [ka]

[0011] [ka]

[0012] (In the above formula (1), R 1 and R 2 Each of the following independently represents a hydrogen atom or a methyl group, X represents a divalent group represented by the following formula (X1) or formula (X2), and in formula (2), W represents a divalent group represented by the following formula (W1) or formula (W2).

[0013] [ka]

[0014] [ka]

[0015] (In the above equation (X1), t represents an integer between 1 and 3, * represents a bond, and in the above equation (X2), R 3 and R 4 (where * represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and * represents a bond.)

[0016] [ka]

[0017] [ka] (In formulas (W1) and (W2) above, * represents a coupling.)

[0018] [ka]

[0019] [ka]

[0020] (In the above formula (5), R 11 represents a phenylene group optionally substituted with an alkyl group or a biphenyldiyl group optionally substituted with an alkyl group, and R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 and R 19 each independently represent a hydrogen atom or a halogen atom. In the above formula (6), R 20 , and R 21 each independently represent an alkyl group or a halogen atom. R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 and R 31 each independently represent a hydrogen atom, a halogen atom, a trifluoromethyl group or a phenoxy group.)

[0021] [Chemical formula]

[0022] [Chemical formula]

[0023] (In the above formula (7) and the above formula (8), R 41 represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms, and R 42 , R 43 , R 46 , R 47 , R 48 , R 50 and R 51 each independently represent an alkyl group having 1 to 8 carbon atoms, R 44 represents an aryl group or a hydrogen atom, and R 45 and R 49(where v1 represents an alkyl group or hydrogen atom with 1 to 8 carbon atoms, and v1, v2, v3, v4, v5, v6, v7, and v8 each independently represent an integer between 0 and 5.)

[0024] According to the above configuration, the surface potential in the exposure area of ​​the electrophotographic photoreceptor can be reduced, allowing for a larger amount of toner to be printed. Furthermore, the change in surface potential during continuous printing can be reduced, preventing fogging (a phenomenon where toner adheres to areas other than the exposure area) during printing. In addition, the transfer memory potential can be suppressed, preventing printing errors due to uneven charging. Thus, according to the above configuration, it is possible to realize an electrophotographic photoreceptor with excellent electrical properties.

[0025] The electron transport agent may consist of a compound represented by the following formulas (9), (10), (11), (12), (13), (14), or (15).

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] (In formulas (9), (10), (11), (12), (13), (14), and (15) above, R 61 , R 62 , R 63 , R 64 , R 65 , R 66 , R 67 , R 68 , R 69 , R 70 , R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 , R 78 , R 79 , R 80 , R 81 , R 82 and R 83 Each of these independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an allyl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms, or an aryl halide group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms.

[0034] To achieve the above objective, a process cartridge according to one embodiment of the present invention comprises the electrophotographic photoreceptor.

[0035] To achieve the above objective, an image forming apparatus according to one embodiment of the present invention comprises an electrophotographic photoreceptor, a charging device, an exposure device, a developing device, and a transfer device. The electrophotographic photoreceptor has the above-described configuration. The charging device charges the surface of the electrophotographic photoreceptor. The exposure apparatus exposes the charged surface to form an electrostatic latent image on the surface. The developing apparatus develops the electrostatic latent image as a toner image. The transfer device transfers the toner image from the electrophotographic photoreceptor to the transfer target.

[0036] The charging device may include a charging roller.

[0037] The developing apparatus may be a two-component developing system. [Effects of the Invention]

[0038] As described above, the present invention can provide an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus that have excellent electrical properties. [Brief explanation of the drawing]

[0039] [Figure 1] This is a schematic diagram of an electrophotographic photoreceptor according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 3] This is a schematic diagram showing the configuration of the image forming unit included in the image forming apparatus described above. [Modes for carrying out the invention]

[0040] An electrophotographic photoreceptor according to an embodiment of the present invention will be described.

[0041] <Configuration of the electrophotographic photoreceptor> Figure 1 is a schematic diagram of an electrophotographic photoreceptor 1 according to one embodiment of the present invention. As shown in the figure, the electrophotographic photoreceptor 1 comprises a conductive substrate 2 and a photosensitive layer 3. The conductive substrate 2 is a cylindrical or cylindrical member made of a conductive material such as metal. The photosensitive layer 3 is provided on the conductive substrate 2. The electrophotographic photoreceptor 1 is a single-layer electrophotographic photoreceptor comprising a single-layer photosensitive layer 3.

[0042] [Composition of the photosensitive layer] The photosensitive layer 3 generates electrons by absorbing light and transports the generated electrons to the surface of the electrophotographic photoreceptor 1 (hereinafter referred to as the photoreceptor surface). The photosensitive layer 3 contains a substrate, a charge generating agent, a dispersion aid, a hole transporter, and an electron transporter, and has a structure in which the charge generating agent, dispersion aid, hole transporter, and electron transporter are dispersed in the substrate. The thickness of the photosensitive layer 3 is not particularly limited, but 5 μm to 100 μm is preferred.

[0043] (base material) The base material is a polyalate resin having repeating units represented by the following formulas (1), (2), (3), and (4), wherein 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 20%.

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] In equation (1), R 1 and R 2 Each of these independently represents a hydrogen atom or a methyl group, X represents a divalent group represented by the following formula (X1) or formula (X2), and in formula (2), W represents a divalent group represented by the following formula (W1) or formula (W2). [ka]

[0049] [ka]

[0050] In equation (X1), t represents an integer between 1 and 3, * represents a combination, and in equation (X2), R 3 and R 4 (where * represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and * represents a bond.)

[0051] [ka]

[0052] [ka]

[0053] In equations (W1) and (W2), * represents a combination.

[0054] Specifically, one or more of the following repeating units can be used as the repeating unit for equation (1): equations (1-1), (1-2), and (1-3).

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] Furthermore, either or both of the following repeating units, (2-1) and (2-2), can be used as the repeating unit for equation (2).

[0059] [ka]

[0060] [ka]

[0061] The above polyalate resin can be produced by condensation polymerization of bisphenol and dicarboxylic acid. Of the repeating units represented by formulas (1), (2), (3), and (4), the repeating units represented by formulas (1) and (3) are derived from bisphenol, and the repeating units represented by formulas (2) and (4) are derived from dicarboxylic acid.

[0062] Specifically, formula (1-1) above is a repeating unit derived from bisphenol CZ shown in formula (1-1a) below, and formula (1-2) above is a repeating unit derived from bisphenol B shown in formula (1-2a) below. Formula (1-3) above is a repeating unit derived from bisphenol Z shown in formula (1-3a) below. In addition, formula (3) above is a repeating unit derived from BP shown in formula (3a) below.

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] Furthermore, formula (2-1) above is a repeating unit derived from 26NACC (2,6-Naphthalenedicarboxylic Acid) shown in formula (2-1a) below, and formula (2-2) above is a repeating unit derived from DCDE (Dicarboxydiphenyl Ether) shown in formula (2-2a) below. Formula (4) above is a repeating unit derived from 14NACC (1,4-Naphthalenedicarboxylic Acid) shown in formula (4a) below.

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] In the polyarate resin, repeating units derived from bisphenol (formulas (1) and (3)) and repeating units derived from dicarboxylic acid (formulas (2) and (4)) are adjacent to each other and bonded together. The repeating unit of formula (1) may be bonded to the repeating unit of formula (2) or to the repeating unit of formula (4). The repeating unit of formula (3) may be bonded to the repeating unit of formula (2) or to the repeating unit of formula (4). The polyarate resin may be a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0072] In polyalate resins, the content (mole fraction; the same applies to content hereafter) of bisphenol and dicarboxylic acid is preferably equal. Of these, the content of bisphenol represented by formula (1) relative to the total number of repeating units represented by formula (1) and formula (3) is preferably 81% to 95%. Furthermore, the content of repeating units represented by formula (3) relative to the total number of repeating units represented by formula (1) and formula (3) is preferably greater than 0% and 20% or less, and more preferably 5% to 19%.

[0073] Furthermore, with respect to dicarboxylic acids, the content of repeating units represented by formula (2) relative to the total number of repeating units represented by formula (2) and formula (4) is preferably 35% to 65%, and the content of repeating units represented by formula (4) relative to the total number of repeating units represented by formula (2) and formula (4) is preferably 35% to 65%.

[0074] The content of each repeating unit in the polyalate resin is determined using a proton nuclear magnetic resonance spectrometer. 1 The H-NMR (Nuclear Magnetic Resonance) spectrum was measured and obtained 1 This can be calculated from the ratio of characteristic peaks for each repeating unit in the H-NMR spectrum.

[0075] The polyalate resin may have end groups. The end groups can be groups derived from DMP (Dimethylphenol) represented by formula (M-1) or groups derived from PFH (Perfluoroheptanol) represented by formula (M-2).

[0076] [ka]

[0077] [ka]

[0078] (Charge-generating agent) The charge-generating agent is titanylphthalocyanine, as shown in the following formula (CG-1).

[0079] [ka]

[0080] The charge generating agent content is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the base material, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0081] (Dispersing agent) The dispersing agent consists of a compound represented by the following formula (5) or formula (6).

[0082] [ka]

[0083] [ka] In equation (5), R 11 R represents a phenylene group which may be substituted with an alkyl group or a biphenyldiyl group which may be substituted with an alkyl group, 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 and R 19 Each of these independently represents a halogen atom. Note that "phenylene group which may be substituted with an alkyl group" means a phenylene group or a phenylene group substituted with one or more alkyl groups. Also, "biphenyldiyl group which may be substituted with an alkyl group" means a biphenyldiyl group or a biphenyldiyl group substituted with one or more alkyl groups. In formula (6), R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R26 , R 27 , R 28 , R 29 , R 30 and R 31 Each of these independently represents a hydrogen atom, a halogen atom, a trifluoromethyl group, or a phenoxy group.

[0084] Specifically, the compound shown in formula (P-1) can be used as the compound shown in formula (5).

[0085] [ka]

[0086] Furthermore, the compounds shown in formula (6) may include the compounds shown in formulas (P-2) and (P-3).

[0087] [ka]

[0088] [ka]

[0089] The content of the dispersing agent is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the base material, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0090] (Hole transport agent) The hole transporter consists of a compound represented by the following formula (7) or formula (8).

[0091] [ka]

[0092] [ka]

[0093] In Formula (7) and the aforementioned Formula (8), R 41 represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms, and R 42 , R 43 , R 46 , R 47 , R 48 , R 50 and R 51 each independently represent an alkyl group having 1 to 8 carbon atoms, R 44 represents an aryl group or a hydrogen atom, and R 45 and R 49 represent an alkyl group having 1 to 8 carbon atoms or a hydrogen atom, and v1, v2, v3, v4, v5, v6, v7, and v8 each independently represent an integer of 0 or more and 5 or less.

[0094] Specifically, as the compound represented by Formula (7), the compounds represented by the following Formula (H-1), Formula (H-2), Formula (H-4), or Formula (H-5) can be used.

[0095]

Chemical formula

[0096]

Chemical formula

[0097]

Chemical formula

[0098]

Chemical formula

[0099] Also, as the compound represented by Formula (8), the compound represented by the following Formula (H-3) can be used.

[0100]

Chemical formula

[0101] The hole transporter content is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the base material, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0102] (Electron transport agent) Examples of electron transport agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. The photosensitive layer 3 may contain only one electron transport agent or two or more electron transport agents.

[0103] Specifically, compounds represented by the following formulas (9), (10), (11), (12), (13), (14), or (15) can be used as electron transport agents.

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] In equations (9), (10), (11), (12), (13), (14), and the previous equation (15), R 61 , R 62 , R 63 , R 64 , R 65 , R 66 , R 67 , R 68 , R 69 , R 70 , R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 , R 78 , R 79 , R 80 , R 81 , R 82 and R 83Each of these independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an allyl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms, or an aryl halide group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms. Note that "an allyl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms" means an allyl group having 6 to 14 carbon atoms or an allyl group having 6 to 14 carbon atoms which is substituted with one or more alkyl groups having 1 to 6 carbon atoms. Also, "an aryl halide group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms" means an aryl halide group having 6 to 14 carbon atoms or an aryl halide group having 6 to 14 carbon atoms which is substituted with one or more alkyl groups having 1 to 6 carbon atoms.

[0112] Specifically, the compound shown in formula (E-1) can be used as the compound shown in formula (9).

[0113] [ka]

[0114] Furthermore, the compound shown in formula (E-7) can be used as the compound shown in formula (10).

[0115] [ka]

[0116] Furthermore, the compound shown in formula (E-6) can be used as the compound shown in formula (11).

[0117] [ka]

[0118] Furthermore, the compound shown in formula (E-5) can be used as the compound shown in formula (12).

[0119] [ka]

[0120] Furthermore, the compound shown in formula (E-8) can be used as the compound shown in formula (13).

[0121] [ka]

[0122] Furthermore, the compound shown in formula (E-3) can be used as the compound shown in formula (14).

[0123] [ka]

[0124] Furthermore, as the compound shown in formula (15), the compounds shown in formula (E-2) or formula (E-4) can be used.

[0125] [ka]

[0126] [ka]

[0127] The electron transport agent content is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the base material, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.

[0128] The photosensitive layer 3 has the above-described structure. In addition to the materials described above, the photosensitive layer 3 may also contain additives. Examples of additives include ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, bulking agents, thickening agents, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, and leveling agents. The photosensitive layer 3 may contain one or more of these additives.

[0129] The electrophotographic photoreceptor 1 only needs to have at least a photosensitive layer 3, and may also have other layers. For example, the electrophotographic photoreceptor 1 may have an undercoat layer provided between the conductive substrate 2 and the photosensitive layer 3, or a protective layer covering the photosensitive layer 3.

[0130] <Manufacturing method for electrophotographic photoreceptors> As a method for manufacturing the electrophotographic photoreceptor 1, the method for manufacturing the substrate will first be described. As mentioned above, the substrate is a polyalate resin, which can be produced by condensation polymerization of bisphenol and dicarboxylic acid. For condensation polymerization, known polymerization methods such as solution polymerization, melt polymerization, or interfacial polymerization can be used.

[0131] In this case, the amounts (mole fractions) of bisphenol and dicarboxylic acid can be equal. Furthermore, the amount of bisphenol in the resulting polyalate resin should be such that the content of the repeating units represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3) described above is greater than 0% and 20% or less.

[0132] Specifically, the bisphenol used is one or more of the following: bisphenol CZ shown in (1-1a) above, bisphenol B shown in formula (1-2a) above, and bisphenol Z shown in formula (1-3a) above, along with BP shown in formula (3a) above. Therefore, the amount (mole fraction) of BP is greater than 0% and 20% or less relative to the total amount of bisphenol CZ, bisphenol B, and bisphenol Z.

[0133] Furthermore, the dicarboxylic acid used is either 26NACC as shown in formula (2-1a) above, or DCDE as shown in formula (2-2a) above and 14NACC as shown in formula (4a) above. By mixing these dicarboxylic acids with the bisphenol prepared as described above and inducing condensation polymerization, a polyalate resin can be produced in which 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 20% or less.

[0134] Furthermore, bisphenol and dicarboxylic acid may be used in derivatized form. End-terminating agents may also be added during condensation polymerization. DMP or PFH can be used as end-terminating agents.

[0135] Next, a method for manufacturing the electrophotographic photoreceptor 1 using the polyalate resin described above will be explained. The electrophotographic photoreceptor 1 can be manufactured by laminating a photosensitive layer 3 on a conductive substrate 2 (see Figure 1). The photosensitive layer 3 can be formed on the conductive substrate 2 by preparing a coating solution by mixing a substrate made of the polyalate resin described above, a charge generating agent, a dispersion aid, a hole transporter, and an electron transporter with a solvent, applying this coating solution to the conductive substrate 2, and removing the solvent. The materials can be mixed using, for example, a bead mill, roll mill, ball mill, attritor, paint shaker, rod-shaped ultrasonic oscillator, or ultrasonic disperser.

[0136] Any solvent capable of dissolving the polyalate resin is acceptable, and examples include alcohols (specifically methanol, ethanol, isopropanol, and butanol), aliphatic hydrocarbons (specifically n-hexane, octane, and cyclohexane), aromatic hydrocarbons (specifically benzene, toluene, and xylene), halogenated hydrocarbons (specifically dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene), ethers (specifically dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether), ketones (specifically acetone, methyl ethyl ketone, and cyclohexanone), esters (specifically ethyl acetate and methyl acetate), dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

[0137] The coating solution can be applied using a method that allows for uniform application, and one of the following methods can be used: dip coating, spray coating, spin coating, or bar coating. The solvent can be removed by heating, reduced pressure, or a combination of heating and reduced pressure, specifically using a high-temperature dryer or a reduced-pressure dryer. The electrophotographic photoreceptor 1 can be manufactured in the manner described above.

[0138] <Effects of electrophotographic photoconductors> The effect of the electrophotographic photoreceptor 1 is explained below. The electrophotographic photoreceptor 1 functions as an image carrier in an image forming device such as a printer. Specifically, the surface of the electrophotographic photoreceptor 1 (hereinafter referred to as the photoreceptor surface) is used in a positively charged state beforehand. When the photoreceptor surface is exposed by an exposure device, electrons generated in the photosensitive layer 3 are transported to the photoreceptor surface, and the positive charge is attenuated. As a result, an electrostatic latent image, which is a region where the charge has been attenuated, is formed in the exposed region (hereinafter referred to as the exposed region) of the photoreceptor surface. When positively charged toner is supplied to the photoreceptor surface, the toner adheres to the electrostatic latent image, and a toner image matching the electrostatic latent image is formed. This toner image is transferred to a printing material such as printing paper, and printing is performed.

[0139] Here, in the electrophotographic photoreceptor 1, the photosensitive layer 3 has the above-described configuration, and therefore has excellent electrical properties for such a printing process. Specifically, in the electrophotographic photoreceptor 1, the surface potential (V) of the exposure region L ) can be reduced. The same surface potential (V L If the surface potential (V) is large, the amount of toner adhering to the electrostatic latent image decreases, and the amount of toner printed also decreases, but if L By reducing the size of the toner used, the amount of toner printed can be increased.

[0140] Furthermore, the electrophotographic photoreceptor 1 can minimize the change in surface potential (ΔV0) during continuous printing. If the change in surface potential (ΔV0) is large, the surface potential decreases with printing, causing "fogging" where toner adheres to areas other than the electrostatic latent image. However, if the change in surface potential (ΔV0) is small, fogging can be prevented. In addition, the electrophotographic photoreceptor 1 can suppress the transfer memory potential. The transfer memory potential is the difference between the surface potential (V3) of an unexposed area (hereinafter referred to as the non-exposed area) and the surface potential (V4) of the non-exposed area to which a transfer bias (2.5kV) is applied. If the transfer memory potential is large, charging unevenness occurs on the photoreceptor surface, but if the transfer memory potential is small, charging unevenness can be prevented. As described above, the electrophotographic photoreceptor 1 can achieve excellent electrical characteristics.

[0141] [Configuration of the image forming apparatus] An image forming apparatus 100 according to an embodiment of the present invention will now be described. Figure 2 is a schematic diagram showing the configuration of the image forming apparatus 100. The image forming apparatus 100 is, for example, a tandem-type color printer.

[0142] As shown in Figure 2, the image forming apparatus 100 comprises a control unit 10, an operation unit 20, a paper feeding unit 30, a transport unit 40, a toner supply unit 50, an image forming unit 60, a transfer device 70, a fixing device 80, and a discharge unit 90.

[0143] The control unit 10 controls the operation of each part of the image forming apparatus 100. The control unit 10 includes an arithmetic processing unit and a storage unit (not shown). The arithmetic processing unit is, for example, a CPU (central processing unit), and the storage unit is, for example, semiconductor memory or an HDD (hard disk drive). The arithmetic processing unit controls the operation of the image forming apparatus 100 by executing a control program. The storage unit stores the control program.

[0144] The control unit 20 receives instructions from the user. Upon receiving instructions from the user, the control unit 20 transmits a signal indicating the user's instructions to the control unit 10. This initiates the image forming operation by the image forming apparatus 100.

[0145] The paper feeding unit 30 includes a paper feeding cassette 31 and a group of paper feeding rollers 32. The paper feeding cassette 31 can accommodate several recording media P. The recording media P is, for example, printing paper. The group of paper feeding rollers 32 feeds the recording media P contained in the paper feeding cassette 31 one sheet at a time to the transport unit 40.

[0146] The transport unit 40 is equipped with rollers and guide members. The transport unit 40 extends from the paper feeding unit 30 to the discharge unit 90. The transport unit 40 transports the recording medium P from the paper feeding unit 30 to the discharge unit 90, passing through the image forming unit 60 and the fixing device 80.

[0147] The toner supply unit 50 supplies toner to the image forming unit 60. The toner supply unit 50 comprises a first mounting unit 51Y, a second mounting unit 51C, a third mounting unit 51M, and a fourth mounting unit 51K. The first mounting unit 51Y is fitted with a first toner container 52Y. The second mounting unit 51C is fitted with a second toner container 52C, the third mounting unit 51M is fitted with a third toner container 52M, and the fourth mounting unit 51K is fitted with a fourth toner container 52K.

[0148] The first toner container 52Y contains yellow toner, and the second toner container 52C contains cyan toner. The third toner container 52M contains magenta toner, and the fourth toner container 52K contains black toner. Note that the color of each toner is not limited to those shown here, and other colors may be used. The number of colors may be one or more.

[0149] The image forming unit 60 includes an exposure device 61, a first image forming unit 62Y, a second image forming unit 62C, a third image forming unit 62M, and a fourth image forming unit 62K. FIG. 3 is a schematic diagram of the image forming unit 62. The first image forming unit 62Y, the second image forming unit 62C, the third image forming unit 62M, and the fourth image forming unit 62K each have the configuration of the image forming unit 62 shown in FIG. 3. The image forming unit 62 has a charging device 63, a developing device 64, a photoreceptor 65, a cleaning device 66, and a discharging device 67. The charging device 63, the developing device 64, the cleaning device 66, and the discharging device 67 are arranged along the surface 65a of the photoreceptor 65.

[0150] The exposure device 61 (see FIG. 2) irradiates light (dashed line in the figure) onto the surface 65a of the photoreceptor 65 included in each image forming unit 62 to expose the surface 65a. Based on the supplied image data, the exposure device 61 irradiates each image forming unit 62 with light for each color to perform exposure. The exposure device 61 can perform exposure using laser light.

[0151] The photoreceptor 65 forms an electrostatic latent image when exposed by the exposure device 61. As the photoreceptor 65, the electrophotographic photoreceptor 1 described above can be used. The surface of the photosensitive layer 3 included in the electrophotographic photoreceptor 1 is used as the surface 65a of the photoreceptor 65. The surface 65a is positively charged in advance. When this surface 65a is exposed by the exposure device 61, the charge decays in the irradiated area, and an electrostatic latent image is formed. The photoreceptor 65 rotates in the direction indicated by the arrow in FIG. 3 (clockwise direction).

[0152] The charging device 63 positively charges the surface 65a. The charging device 63 comprises a charging roller 631, a charging voltage power supply 632, and a cleaning brush 633. The charging roller 631 contacts the surface 65a to uniformly charge the surface 65a. The charging voltage power supply 632 applies a charging voltage to the charging roller. A DC voltage is preferred for this charging voltage. The cleaning brush 633 contacts the charging roller 631 to clean it.

[0153] The developing device 64 supplies toner supplied from the toner supply unit 50 to the surface 65a. As shown in Figure 3, the developing device 64 is equipped with a developing roller 641. The toner supplied from the toner container is mixed with a magnetic carrier to form a two-component developer. At this time, the toner becomes charged with the same polarity (positive) as the surface 65a due to friction with the carrier.

[0154] The two-component developer is attracted to the developing roller 641 by magnetic force and transported to a position opposite the photoreceptor 65. A voltage is applied between the developing roller 641 and the photoreceptor 65, causing the toner in the two-component developer to adhere to the electrostatic latent image on the surface 65a. This forms a toner image on the surface 65a that matches the electrostatic latent image.

[0155] The developing device 64 of the first image forming unit 62Y is connected to the first toner container 52Y, and yellow toner is supplied. As a result, a yellow toner image is formed on the surface of the photoreceptor 65 of the first image forming unit 62Y. Similarly, the developing device 64 of the second image forming unit 62C is connected to the second toner container 52C, and a cyan toner image is formed on the surface of the photoreceptor 65 of the second image forming unit 62C.

[0156] Furthermore, the developing device 64 of the third image forming unit 62M is connected to the third toner container 52M, and a magenta toner image is formed on the surface of the photoreceptor 65 of the third image forming unit 62M. The developing device 64 of the fourth image forming unit 62K is connected to the fourth toner container 52K, and a black toner image is formed on the surface of the photoreceptor 65 of the fourth image forming unit 62K.

[0157] The cleaning device 66 recovers toner adhering to the surface 65a after transfer by the primary transfer roller 71, which will be described later. Specifically, the cleaning device 66 includes a cleaning blade 661 and a static elimination device 67. The cleaning blade 661 is pressed against the surface 65a and cleans the surface 65a by recovering the toner adhering to it. The static elimination device 67 removes static electricity from the surface 65a by irradiating it with static elimination light.

[0158] The transfer device 70 (see Figure 2) transfers the toner image from the photoreceptor 65 to the recording medium P, which is the object to be transferred. Specifically, the transfer device 70 transfers the toner images of each color formed on the surface 65a of the photoreceptor 65 of each image forming unit 62 onto the recording medium P. The transfer device 70 can transfer each toner image onto the recording medium P by a secondary transfer method (intermediate transfer method). For the secondary transfer method, the transfer device 70 has four primary transfer rollers 71, an intermediate transfer belt 72, a drive roller 73, a driven roller 74, and a secondary transfer roller 75.

[0159] The intermediate transfer belt 72 is an endless belt stretched over four primary transfer rollers 71, a drive roller 73, and a driven roller 74. The intermediate transfer belt 72 is driven in accordance with the rotation of the drive roller 73. In Figure 2, the intermediate transfer belt 72 rotates in the direction indicated by the arrow in Figure 2 (counterclockwise). The driven roller 74 is rotationally driven in accordance with the driving of the intermediate transfer belt 72.

[0160] Each image forming unit 62 faces the lower surface of the intermediate transfer belt 72 and is arranged in the order of the first image forming unit 62Y to the fourth image forming unit 62K, from the upstream side to the downstream side in the driving direction of the lower surface of the intermediate transfer belt 72.

[0161] Each primary transfer roller 71 is positioned opposite each photoreceptor 65 via an intermediate transfer belt 72 and is pressed toward each photoreceptor 65. As a result, the toner image formed on the surface 65a of each photoreceptor 65 is sequentially transferred to the intermediate transfer belt 72 by each primary transfer roller 71. In the configuration shown in Figure 2, the yellow toner image, cyan toner image, magenta toner image, and black toner image are transferred to the intermediate transfer belt 72 in this order, but the order of the toner images is not limited to this. Hereinafter, the toner image formed by stacking the yellow toner image, cyan toner image, magenta toner image, and black toner image will be referred to as the "stacked toner image".

[0162] The secondary transfer roller 75 is positioned opposite the drive roller 73 via the intermediate transfer belt 72. The secondary transfer roller 75 is pressed toward the drive roller 73. This forms a transfer nip (contact area) between the secondary transfer roller 75 and the drive roller 73, and as the recording medium P passes through the transfer nip, the secondary transfer roller 75 transfers the layered toner image on the intermediate transfer belt 72 to the recording medium P. The layering order of the layered toner image on the recording medium P is the opposite of the layering order of the layered toner image on the intermediate transfer belt 72. The recording medium P on which the layered toner image has been transferred is transported toward the fuser 80 by the transport unit 40.

[0163] The fuser unit 80 fixes the stacked toner image onto the recording medium P. The fuser unit 80 includes a heating member 81 and a pressurizing member 82. The heating member 81 and the pressurizing member 82 are arranged facing each other to form a fuser nip. The recording medium P, transported from the image forming unit 60, is heated and pressurized at a predetermined fixing temperature as it passes through the fuser nip, and the stacked toner image is fixed onto the recording medium P. The recording medium P is transported from the fuser unit 80 to the discharge unit 90 by the transport unit 40.

[0164] The discharge unit 90 discharges the recording medium P on which the stacked toner image has been fixed. The discharge unit 90 has a pair of discharge rollers 91, a discharge port 92, and a discharge tray 93. The pair of discharge rollers 91 transports the recording medium P to the discharge tray 93 via the discharge port 92.

[0165] The image forming method using the image forming apparatus 100 will now be described. When the control unit 10 acquires image data and the operation unit 20 receives a user instruction to start the image forming operation, the photoreceptor 65 in each image forming unit 62 is rotated, and the charging roller 631 uniformly positively charges the surface 65a. Next, the exposure apparatus 61 exposes the surface 65a of each image forming unit 62 according to the image data, forming electrostatic latent images for each color on the surface 65a. Specifically, electrons generated by exposure are transported to the surface 65a, and the positive charge is attenuated by these electrons, thereby forming the electrostatic latent image.

[0166] Each image forming unit's developing device 64 supplies toner of each color to the surface 65a, which then electrostatically adheres to the electrostatic latent image for each color. This forms a toner image of each color on the surface 65a of each photoreceptor 65. If the amount of toner filled in each developing device 64 falls below a specified value due to the formation of the toner image, toner is replenished to each developing device 64 from the first toner container 52Y to the fourth toner container 52K.

[0167] An electric field is applied between the primary transfer roller 71 and the photoreceptor 65 at a predetermined transfer voltage by the primary transfer roller 71. As a result, the toner images of each color on the surface 65a are primary transferred onto the intermediate transfer belt 72. The toner images of each color are stacked, and a stacked toner image is formed on the intermediate transfer belt 72. Subsequently, in preparation for the formation of a new electrostatic latent image, any toner remaining on the surface 65a after the primary transfer is removed by the cleaning device 66.

[0168] When the intermediate transfer belt 72 rotates counterclockwise as the driving roller 73 rotates, the recording medium P is conveyed to the transfer nip between the secondary transfer roller 75 and the driving roller 73 at a predetermined timing by the conveying unit 40, and the laminated toner image on the intermediate transfer belt 72 is secondarily transferred onto the recording medium P. The recording medium P onto which the laminated toner image has been secondarily transferred is conveyed to the fixing device 80 by the conveying unit 40.

[0169] The recording medium P conveyed to the fixing device 80 is heated and pressurized by the heating member 81 and the pressurizing member 82, so that the laminated toner image is fixed on the surface of the recording medium P, and a color image is formed on the recording medium P. The recording medium P on which the color image has been formed is discharged to the discharge tray 93 at the discharge unit 90.

[0170] The image forming apparatus 100 has the above-described configuration. The configuration of the image forming apparatus according to the present invention is not limited to the above, and any apparatus may be used as long as it includes a photoreceptor 65 having the configuration of the electrophotographic photoreceptor 1. For example, although the image forming apparatus 100 is an image forming apparatus capable of forming a color image, the image forming apparatus according to the present invention may be an image forming apparatus capable of forming a monochrome image. In this case, the image forming apparatus may be provided with only one image forming unit.

[0171] Further, although the developing device 64 has been described as a two-component developing system that supplies a two-component developer to the surface 65a, it may be a one-component developing system that supplies a one-component developer to the surface 65a. The one-component developer is a developer composed only of toner without being mixed with a carrier. Furthermore, the developing device 64 may be a rubbing roller system including a roller that rubs the surface 65a.

[0172] Also, although the image forming apparatus 100 is a tandem-type image forming apparatus, the image forming apparatus according to the present invention may be a rotary-type image forming apparatus. Furthermore, although the image forming apparatus 100 is an image forming apparatus using a touch-down developing method, the image forming apparatus according to the present invention may be an image forming apparatus using a developing method other than the touch-down developing method.

[0173] Furthermore, although the image forming apparatus 100 is an intermediate transfer type image forming apparatus, the image forming apparatus according to the present invention may be a direct transfer type image forming apparatus. In this case, the toner image is directly transferred from the photoreceptor 65 to the recording medium P while the photoreceptor 65 is in contact with the recording medium P.

[0174] [Process Cartridge Configuration] A process cartridge according to an embodiment of the present invention will now be described. The process cartridge according to this embodiment corresponds to part or all of the image forming unit 62 (see Figure 3) described above and comprises at least a photoreceptor 65. In addition, the process cartridge according to this embodiment may also comprise at least one of a charging device 63, a developing device 64, a cleaning device 66, and a static elimination device 67, in addition to the photoreceptor 65.

[0175] The process cartridge is configured to be detachable from the image forming apparatus 100. This allows for easy replacement of the entire process cartridge when the sensitivity characteristics of the photoreceptor 65 deteriorate, for example. [Examples]

[0176] Electrophotographic photoreceptors according to the examples and comparative examples of the present invention were prepared, and various physical properties were measured. Table 1 below shows the composition and measurement results of the electrophotographic photoreceptors according to the examples and comparative examples.

[0177] [Table 1]

[0178] <Fabrication of electrophotographic photoreceptors> The electrophotographic photoreceptors for the examples and comparative examples were prepared as follows.

[0179] First, polyalate resins were prepared to serve as the substrate for the photosensitive layer. Table 2 below shows the composition of each polyalate resin. In Table 2, notations such as (1-1) indicate the repeating units of the above formula (1-1).

[0180] [Table 2]

[0181] In Table 2, "Resin A" to "Resin J" satisfy the substrate configuration described in the above embodiment. That is, "Resin A" to "Resin J" are polyalate resins consisting of repeating units represented by the above formulas (1), (2), (3), and (4), and 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 20%.

[0182] For example, "Resin A" is formed by condensation polymerization of bisphenol containing bisphenol CZ (95% content) and BP (5% content) and dicarboxylic acid containing 14NACC (50% content) and 26NACC (50% oil content), and is a polyalate resin in which the repeating units of formula (1-1) account for 95%, the repeating units of formula (3) account for 5%, the repeating units of formula (2-1) account for 50%, and the repeating units of formula (4) account for 50%. Therefore, in "Resin A", the content of the repeating units represented by formula (3) relative to the total number of repeating units represented by formulas (1) and (3) is 5%. Similarly, in "Resin B" to "Resin J", the content of the repeating units 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 20%.

[0183] On the other hand, "Resin K" to "Resin P" are resins that do not satisfy the substrate composition described in the above embodiment. Specifically, "Resin K" does not contain the repeating unit of formula (3), and "Resin L" does not contain the repeating units of formulas (2) and (4). Instead of these, "Resin L" uses TPC (terephthalic acid) shown in formula (C-1) and IPC (isophthalic acid) shown in formula (C-2) below as dicarboxylic acids. "Resin M" also does not contain the repeating unit of formula (3).

[0184] [ka]

[0185] [ka]

[0186] "Resin N" has the structure shown in formula (S-1) below, and "Resin O" has the structure shown in formula (S-2) below. "Resin P" has the structure shown in formula (S-3) below.

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] Next, 100 parts of the base material, 2 parts of the charge generating agent, 1.3 parts of the dispersion aid, 70 parts of the hole transporter, and 50 parts of the electron transporter were dispersed in 500 parts of the solvent (tetrohydrofuran). The charge generating agent was Y-type titanyl phthalocyanine, and the other materials were those shown in Table 1. For example, in Example 1, 100 parts of resin A, 2 parts of Y-type titanyl phthalocyanine, 1.3 parts of the dispersion aid represented by formula (P-1), 70 parts of the hole transporter represented by formula (H-1), and 50 parts of the electron transporter represented by formula (E-1) were dispersed in 500 parts of the solvent (tetrohydrofuran).

[0191] Dispersion was performed using a rod-shaped ultrasonic oscillator for 20 minutes. The prepared solution was filtered using a 5 μm mesh filter to prepare a coating solution. This coating solution was applied to a conductive substrate by dip-coating and dried at 120°C for 50 minutes to form a photosensitive layer. The thickness of the photosensitive layer was 30 μm.

[0192] Note that "H-6" to "H-9" in Table 1 are hole transporters represented by the following formulas (H-6) to (H-9), and are not included in the hole transporters according to the above embodiment (hole transporters represented by formula (7) or formula (8)).

[0193] [ka]

[0194] [ka]

[0195] [ka]

[0196] [ka]

[0197] To explain the differences between the comparative examples and the examples, the electrophotographic photoreceptors in Comparative Examples 1 to 4 have hole transporters (H-6 to H-9) in the photosensitive layer that are not the hole transporters according to the above embodiment, and the electrophotographic photoreceptors in Comparative Examples 9 to 14 have polyalate resins (resins K to P) that are the substrates of the photosensitive layer that are not the polyalate resins according to the above embodiment. In addition, the electrophotographic photoreceptor in Comparative Example 15 does not contain a dispersion aid in the photosensitive layer. On the other hand, the electrophotographic photoreceptors in Examples 1 to 23 have the configuration described in the above embodiment.

[0198] The electrophotographic photoreceptors according to the examples and comparative examples prepared as described above were mounted on an evaluation machine, and printing and various measurements were performed. The evaluation machine was a "TASKalfa MA4500ci" printer (manufactured by Kyocera Document Solutions Corporation) and uses an intermediate transfer method. The evaluation machine is equipped with a charging roller made of electrostatically charged rubber (epichlorohydrin resin with conductive carbon dispersed). The charging polarity of the electrophotographic photoreceptor was set to positive electrode, and the applied voltage was a DC voltage.

[0199] For the electrophotographic photoreceptor mounted in the evaluation unit, the electrophotographic photoreceptor's charging potential was set to 470±30V in an environment of 23°C and 50% humidity, and exposure was performed on the surface of the photoreceptor. The exposure was performed with a wavelength of 780nm, a width at half maximum of 20nm, and a light intensity of 0.8μJ / m². 2 These were the conditions.

[0200] After exposure, the post-exposure potential V, the surface potential V3 of the unexposed area, and the surface potential V4 of the unexposed area with a transfer bias (2.5kV) applied were measured. The exposed area is the area where toner adheres, and the unexposed area is the area where toner does not adhere (blank area). The post-exposure potential V is the potential at the development position measured with a surface probe after exposure.

[0201] The change in surface potential ΔV0 was calculated from the initial potential V0 (470V) and the potential V after exposure using the following equation. ΔV0 = V0 - V

[0202] Furthermore, the transfer memory potential ΔVtc was calculated from the surface potential V3 of the unexposed region and the surface potential V4 of the unexposed region to which the transfer bias was applied, using the following equation. ΔVtc = V3 - V4

[0203] Surface potential V of the exposure region L Table 1 shows the change in surface potential ΔV0 and the transfer memory potential ΔVtc. As shown in Table 1, the electrophotographic photoreceptors of Examples 1 to 23 had a surface potential change ΔV0 that was close to 0, while the electrophotographic photoreceptors of Comparative Examples 1 to 15 had a large change in surface potential ΔV0. Therefore, it can be said that the electrophotographic photoreceptors of Examples 1 to 23 have a small change in surface potential during printing, and are less prone to "fogging," where toner adheres to areas other than the electrostatic latent image.

[0204] Furthermore, the electrophotographic photoreceptors in Examples 1 to 23 had a small transfer memory potential ΔVtc, while the electrophotographic photoreceptors in Comparative Examples 1 to 15 had a large transfer memory potential ΔVtc. Therefore, it can be said that the electrophotographic photoreceptors in Examples 1 to 23 are capable of preventing printing errors due to uneven charging. [Explanation of Symbols]

[0205] 1…Electrophotographic photoreceptor 2…Conductive substrate 3…Photosensitive layer 10…Control Unit 20...Operation unit 30…Paper feed section 40…Conveyor Unit 50... Toner Refill Unit 60…Image forming unit 65...Photoreceptor 70…Transfer device 80… Fixing device 90…Discharge section 100…Image forming apparatus

Claims

1. A conductive substrate, A photosensitive layer provided on the conductive substrate, Equipped with, The photosensitive layer contains a substrate, a charge generating agent, a dispersion aid, a hole transporter, and an electron transporter. The substrate is a polyarate resin having repeating units represented by the following formulas (1), (2), (3), and (4), wherein 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 20%. The charge generating agent is titanylphthalocyanine. The aforementioned dispersing agent consists of a compound represented by the following formula (5) or formula (6): The hole transporter consists of a compound represented by the following formula (7) or formula (8). Electrophotographic photoreceptor. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 (In formula (1) above, R １ and R ２ Each of the following independently represents a hydrogen atom or a methyl group, X represents a divalent group represented by the following formula (X1) or formula (X2), and in formula (2), W represents a divalent group represented by the following formula (W1) or formula (W2). 【Transformation 5】 【Transformation 6】 (In the above formula (X1), t represents an integer between 1 and 3, * represents a bond, and in the above formula (X2), R ３ and R ４ (where * represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and * represents a bond.) 【Transformation 7】 【Transformation 8】 (In formulas (W1) and (W2) above, * represents a coupling.) 【Chemistry 9】 【Chemistry 10】 (In the above formula (5), R １１ represents a phenylene group optionally substituted with an alkyl group or a biphenyldiyl group optionally substituted with an alkyl group, and R １２ , R １３ , R １４ , R １５ , R １６ , R １７ , R １８ and R １９ each independently represent a halogen atom, and in the above formula (6), R ２０ , and R ２１ each independently represent an alkyl group or a halogen atom, and R ２２ , R ２３ , R ２４ , R ２５ , R ２６ , R ２７ , R ２８ , R ２９ , R ３０ and R ３１ each independently represent a hydrogen atom, a halogen atom, a trifluoromethyl group or a phenoxy group.) 【Chemistry 11】 【Chemistry 12】 (In formulas (7) and (8) above, R ４１ R represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms, ４２ , R ４３ , R ４６ , R ４７ , R ４８ , R ５０ and R ５１ Each of these independently represents an alkyl group having 1 to 8 carbon atoms, R ４４ R represents an aryl group or a hydrogen atom. ４５ and R ４９ (where v1 represents an alkyl group or hydrogen atom having 1 to 8 carbon atoms, and v1, v2, v3, v4, v5, v6, v7, and v8 each independently represent an integer between 0 and 5.)

2. The electrophotographic photoreceptor according to claim 1, The electron transport agent comprises a compound represented by the following formulas (9), (10), (11), (12), (13), (14), or (15). Electrophotographic photoreceptor. 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 【Chemistry 17】 [Chemistry 18] 【Chemistry 19】 (In formulas (9), (10), (11), (12), (13), (14), and (15), R ６１ , R ６２ , R ６３ , R ６４ , R ６５ , R ６６ , R ６７ , R ６８ , R ６９ , R ７０ , R ７１ , R ７２ , R ７３ , R ７４ , R ７５ , R ７６ , R ７７ , R ７８ , R ７９ , R ８０ , R ８１ , R ８２ and R ８３ Each of these independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an allyl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms, or an aryl halide group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms.

3. Electrophotographic photoreceptor according to claim 1 or 2 A process cartridge equipped with [a specific feature].

4. An electrophotographic photoreceptor according to claim 1 or 2, A charging device for charging the surface of the electrophotographic photoreceptor, An exposure apparatus that exposes the charged surface to form an electrostatic latent image on the surface, A developing apparatus that develops the electrostatic latent image as a toner image, A transfer device for transferring the toner image from the electrophotographic photoreceptor to a transfer target. An image forming apparatus comprising the following:

5. An image forming apparatus according to claim 4, The charging device comprises a charging roller. Image forming apparatus.

6. An image forming apparatus according to claim 4 or 5, The developing apparatus is a two-component developing system. Image forming apparatus.

Images