Electrophotographic photoreceptor, method for manufacturing the same, and electrophotographic apparatus

Abstract

The present invention provides an electrophotographic photoreceptor, a method for manufacturing the same, and an electrophotographic apparatus which have less wear during long-term use, can maintain a high holding rate with high sensitivity in terms of electrical characteristics, and can achieve a stable image without film formation. The photoreceptor includes a conductive substrate (1), a charge generation layer (3), and a charge transport layer (4). The charge transport layer contains a hole transport material, a resin binder, an electron transport material, and an inorganic oxide. The charge generation layer contains a charge generation material. The masses a to d of the hole transport material, the resin binder, the electron transport material, and the inorganic oxide in the charge transport layer satisfy 1.5 ≤ b / a ≤ 5.7, 0.005 ≤ c / a ≤ 0.35, 0.05 ≤ d / a ≤ 0.70, a ≥ c + d, and c / d ≥ 0.01. The hole transport material contains a compound of formula (A-1). The charge generation material contains oxytitanium phthalocyanine having an exothermic peak at 251 °C ± 5 °C, a half-peak width of 15 °C or less, a calorific value of 1.0 mJ / mg or more, and an X-ray diffraction peak at 27.2° ± 0.3° when the temperature rising condition in differential scanning calorimetry is 20 °C / minute.

Description

Technical Field

[0001] The present invention relates to an electrophotographic photosensitive member (hereinafter also simply referred to as "photosensitive member") used in an electrophotographic printer, copier, fax machine, etc., a method for manufacturing the same, and an electrophotographic apparatus. The present invention particularly relates to an electrophotographic photosensitive member capable of achieving excellent abrasion resistance and stability of electrical characteristics by containing specific charge transport materials and charge generation materials in a photosensitive layer, a method for manufacturing the same, and an electrophotographic apparatus. Background Art

[0002] An electrophotographic photosensitive member has a basic structure in which a photosensitive layer having a photoconductive function is provided on a conductive substrate. In recent years, regarding an organic electrophotographic photosensitive member using an organic compound as a functional component responsible for charge generation and transport, research and development have been actively carried out due to advantages such as material diversity, high productivity, and safety, and its application in copiers and printers has also been progressing.

[0003] Generally, a photosensitive member must have a function of maintaining surface charges in the dark, a function of receiving light and generating charges, and a function of transporting the generated charges. The photosensitive layer plays these roles. The photosensitive member is classified into a so-called single-layer type photosensitive member and a laminated type (function-separated type) photosensitive member according to the form of the photosensitive layer. The single-layer type photosensitive member has a single photosensitive layer having both a charge generation function and a charge transport function. The laminated type photosensitive member has a photosensitive layer formed by laminating a charge generation layer and a charge transport layer. The charge generation layer mainly plays a role of generating charges when receiving light. The charge transport layer plays a role of maintaining surface charges in the dark and transporting charges generated in the charge generation layer when receiving light.

[0004] The above photosensitive layer is usually formed by coating a coating liquid in which a charge generation material, a charge transport material, and a resin binder are dissolved or dispersed in an organic solvent on a conductive substrate. In these organic electrophotographic photosensitive members, particularly in the outermost surface layer, polycarbonate having strong friction with paper or a doctor blade for removing toner, excellent flexibility, and good transmittance of exposure is mostly used as the resin binder. Among them, bisphenol Z type polycarbonate is widely used as the resin binder. A technique using this polycarbonate as the resin binder is described, for example, in Patent Document 1 and the like.

[0005] In addition, in recent years, with the increase in the number of printed sheets due to the networking in offices and the rapid development of portable printers due to electrophotography, etc., electrophotographic printing apparatuses are increasingly required to have high abrasion resistance, that is, high durability, high sensitivity, and high-speed response.

[0006] In addition, with the recent development and increase in popularity of color printers, the printing speed is increasing, the device is becoming smaller and the components are being saved, and it is also required to cope with various usage environments. Under such circumstances, the demand for photoreceptors with small changes in image characteristics or electrical characteristics due to repeated use or changes in the usage environment (room temperature and environment) is significantly increasing, and the previous technology cannot fully meet these requirements at the same time.

[0007] In order to solve these problems, various methods for improving the outermost surface layer of the photoreceptor have been proposed.

[0008] In order to improve the durability of the photoreceptor surface, various polycarbonate resin structures have been proposed. For example, in Patent Documents 2 to 4, schemes containing polycarbonate resins with specific structures are proposed, but the compatibility with various charge transport agents or additives and the solubility of the resin are not sufficiently studied, and there is also a problem that stable electrical properties are difficult to maintain during long-term use. In addition, in Patent Document 5, a scheme containing polycarbonate resins with specific structures is proposed, but in a resin with a large structure, the space between polymers is large, and discharge materials, contact components, foreign matter, etc. when charged can easily penetrate into the photosensitive layer, so that the filming phenomenon (Japanese: フィィルミング phenomenon) of toner adhering to the photosensitive layer occurs, and it is difficult to obtain sufficient durability. In addition, in order to improve the wear resistance, Patent Document 6 proposes a scheme in which the photosensitive layer contains filler particles. However, the influence of the agglomeration of particles on the photosensitive body characteristics when preparing the photosensitive layer coating liquid, and the influence of the film-forming phenomenon in which the toner components adhere to the photosensitive body due to the affinity between the agglomerates and the toner components have not been fully verified.

[0009] In order to solve these technical problems, it has been proposed to use a combination of materials with specific structures as described in Patent Documents 7 to 9 in the photosensitive layer.

[0010] On the other hand, Patent Document 10 proposes a method of forming a surface layer containing a curable resin on the outermost surface of a photosensitive layer, wherein the curable resin is a cured product containing a compound having a cross-linked structure and a charge transporting structure. However, in this case, since a surface layer is additionally provided on the photosensitive layer, the number of production steps increases and the number of interfaces increases, which may cause a decrease in charge transporting properties and make it difficult to obtain sufficient sensitivity.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Publication No. 61-62040

[0014] Patent Document 2: Japanese Patent Application Publication No. 2004-354759

[0015] Patent Document 3: Japanese Patent Laid-Open No. 4-179961

[0016] Patent Document 4: Japanese Patent Laid-Open No. 3-273256

[0017] Patent Document 5: Japanese Patent Laid-Open No. 2004-85644

[0018] Patent Document 6: Japanese Patent Laid-Open No. 2008-176054

[0019] Patent Document 7: International Publication No. 2018 / 003229

[0020] Patent Document 8: International Publication No. 2019 / 159342

[0021] Patent Document 9: International Publication No. 2018 / 150693

[0022] Patent Document 10: Japanese Patent Laid-Open No. 2016-9066 Summary of the Invention

[0023] Technical Problem to be Solved by the Invention

[0024] As described above, various technical solutions have been proposed regarding the improvement of the outermost surface layer of the photoreceptor. However, the technologies described in these patent documents are insufficient for durability, electrical properties, abrasion resistance, image defects caused by film formation, etc. during long-term actual use.

[0025] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor, a manufacturing method thereof, and an electrophotographic apparatus that have little wear during long-term use, can maintain a high holding rate of electrical properties with high sensitivity, and can achieve a stable image without film formation.

[0026] Technical Solution for Solving the Technical Problem

[0027] As a result of in-depth research on the materials of the photosensitive layer by the present inventor to solve the above technical problems, a photoreceptor with improved abrasion resistance and film formation resistance, high sensitivity, and little reduction in potential holding rate even when repeatedly used, and excellent stability is provided. Specifically, the present inventor found that by adopting the following configuration, a good electrophotographic photoreceptor can be obtained, and finally completed the present invention.

[0028] That is, the first form of the present invention is an electrophotographic photoreceptor comprising at least a conductive substrate and a photosensitive layer provided on the conductive substrate and sequentially having a charge generation layer and a charge transport layer, wherein the charge transport layer contains a hole transport material, a resin binder, an electron transport material, and an inorganic oxide, the charge generation layer contains a charge generation material, and when the mass of the hole transport material contained in the charge transport layer is denoted as a, the mass of the resin binder is denoted as b, the mass of the electron transport material is denoted as c, and the mass of the inorganic oxide is denoted as d, a, b, c, and d satisfy the conditions shown in the following formulas 1 to 5:

[0029] Formula 1: 1.5 ≤ b / a ≤ 5.7

[0030] Formula 2: 0.005 ≤ c / a ≤ 0.35

[0031] Formula 3: 0.05 ≤ d / a ≤ 0.70

[0032] Formula 4: a ≥ c + d

[0033] Formula 5: c / d ≥ 0.01

[0034] The hole transport material contains a compound having a structure represented by the following general formula (A-1), and the charge generation material contains oxytitanium phthalocyanine having an exothermic peak at 251 °C ± 5 °C when the temperature increase condition in differential scanning calorimetry is 20 °C / minute, the half-width at half-maximum of the exothermic peak is 15 °C or less, the calorific value is 1.0 mJ / mg or more, and having a diffraction peak at 27.2 ° ± 0.3 ° in X-ray diffraction.

[0035]

[0036] (In formula (A-1), Re, Rf, Rg, and Ri each independently represent a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted styryl group, Rh represents a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted styryl group, or a structural unit represented by the following general formula (Rh1) or (Rh2), x and z represent integers from 0 to 4, j and y represent integers from 0 to 5, n represents an integer from 1 to 2, q represents an integer from 0 to 2, and r represents an integer from 0 to 1.)

[0037]

[0038] (In formulas (Rh1) and (Rh2), Rj, Rk, and Rm each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, t represents an integer from 0 to 5, s represents an integer from 0 to 1, and * represents a bonding site.)

[0039] By containing the above-mentioned specific hole transporting material, resin binder, electron transporting material, and inorganic oxide in the charge transporting layer that constitutes the outermost surface layer in the photosensitive layer at a specified mass ratio, the mechanical strength of the photosensitive layer can be improved, and the occurrence of film formation can be suppressed. Further, by using a charge generating material having specific thermal characteristics in the charge generating layer, a high-quality electrophotographic photoreceptor that can maintain high sensitivity and high holding ratio even during rubbing can be provided.

[0040] The above-mentioned electron transporting material preferably contains any one of the compounds represented by the following structural formulas (E-1) to (E-5), and may also contain a plurality of them.

[0041]

[0042] (In formulas (E-1), (E-2), (E-3), and (E-4), R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 16 、R 17 、R 18 、R 19 each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 or more and 6 or less carbon atoms that may have a substituent, an alkenyl group having 2 or more and 6 or less carbon atoms that may have a substituent, an alkoxy group having 1 or more and 6 or less carbon atoms that may have a substituent, an aryl group having 6 or more and 14 or less carbon atoms that may have a substituent, or a cycloalkyl group having 3 or more and 8 or less carbon atoms that may have a substituent, and u represents an integer of 0 to 5;

[0043] In formula (E-5), R 14 and R 15 each independently represents an aryl group having 6 or more and 14 or less carbon atoms that may have at least 1 alkyl group having 1 or more and 6 or less carbon atoms, an aryl group having 6 or more and 14 or less carbon atoms that may have a phenylcarbonyl group, an aralkyl group having 7 or more and 20 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, an alkyl group having 1 or more and 8 or less carbon atoms that may have an alkylamino group, or a cycloalkyl group having 3 or more and 10 or less carbon atoms;

[0044] The above-mentioned selected groups may be substituted by 1 or more halogen atoms.

[0045] In addition, the above-mentioned resin binder preferably contains a resin having a viscosity-reduced molecular weight of 15,000 or more and having a repeating unit represented by the following structural formula (BD-1).

[0046]

[0047] (In formula (BD-1), R1 and R2 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, W represents a single bond, an oxygen atom, a sulfur atom or CR3R4, R3 and R4 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R3 and R4 may combine with each other to form a substituted or unsubstituted cycloalkyl group having 5 to 6 carbon atoms.)

[0048] In addition, it is preferable that the above inorganic oxide has silica as a main component, contains 1 ppm or more and 2000 ppm or less of aluminum element, and is surface-treated with a silane coupling agent having a structure represented by the following general formula (1).

[0049] (R 21 ) n -Si-(OR 22 ) 4-n (1)

[0050] (In the formula, Si represents a silicon atom, R 21 represents an organic group in a form where carbon is directly bonded to the silicon atom, R 22 represents an organic group, and n represents an integer of 0 to 3.)

[0051] In this case, the above silane coupling agent preferably contains at least one selected from phenyltrimethoxysilane, vinyltrimethoxysilane, epoxytrimethoxysilane, methacrylic acid trimethoxysilane, aminotrimethoxysilane, ureidotrimethoxysilane, mercaptopropyltrimethoxysilane, isocyanatopropyltrimethoxysilane, phenylaminotrimethoxysilane, acrylic acid trimethoxysilane, p-styryltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0052] In addition, it is preferable that the above inorganic oxide is surface-treated with a plurality of the above silane coupling agents, and the silane coupling agent initially used in the surface treatment has a structure represented by the above general formula (1).

[0053] The second aspect of the present invention is a method for manufacturing an electrophotographic photoreceptor, which includes: when manufacturing the above electrophotographic photoreceptor, using a coating liquid for a charge generation layer for forming the above charge generation layer and a coating liquid for a charge transport layer for forming the above charge transport layer, and forming the above charge generation layer and charge transport layer by dip coating method.

[0054] The third aspect of the present invention is an electrophotographic apparatus formed by mounting the above electrophotographic photoreceptor.

[0055] Advantages of the Invention

[0056] According to the present invention, by forming a photosensitive layer that satisfies the above conditions, the mechanical strength of the photosensitive layer can be improved, and high sensitivity and high holding ratio during brushing can be maintained. Furthermore, a high-quality electrophotographic photoreceptor without film formation can be obtained.

[0057] It is considered that this is due to the following reasons. In the present invention, by including a resin binder and an inorganic oxide having a specific structure in the charge transport layer that forms the outermost layer in the photosensitive layer, the mechanical strength of the photosensitive layer can be improved. However, when more than a certain amount of inorganic oxide is added to the photosensitive layer, the aggregates of the inorganic oxide increase, which may cause a decrease in sensitivity due to a reduction in film permeability, or the occurrence of minute defects in the image, or a film formation phenomenon in which the toner components adhere to the photosensitive layer starting from the aggregates of the inorganic oxide, thereby causing image failure. In addition, by adding more than a certain amount of resin, it is also possible to reduce the sensitivity and fail to obtain sufficient characteristics.

[0058] In contrast, in the present invention, by using a hole transport material having a specific structure that exhibits high mobility by increasing the resin amount in the charge transport layer that forms the outermost surface layer in the photosensitive layer, and setting the blending amounts of the respective components in the charge transport layer to a specified ratio, an effect of having abrasion resistance during brushing and not undergoing film formation can be obtained. Furthermore, by including a charge generation material having specific thermal characteristics in the photosensitive layer, an electrophotographic photoreceptor having stable electrical characteristics relative to the initial state even after brushing can be provided. In addition, a certain range of inorganic oxide that can impart mechanical strength to the charge transport layer and does not increase the aggregates can be included. In addition, as the resin binder in the charge transport layer, by using a resin binder having a resin skeleton with a specific structure, higher durability can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 FIG. is a schematic cross-sectional view showing an example of an electrophotographic photoreceptor according to an embodiment of the present invention.

[0060] Figure 2 FIG. is a simplified configuration diagram showing an example of an electrophotographic apparatus according to an embodiment of the present invention.

[0061] Figure 3 FIG. is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM1 used in the examples.

[0062] Figure 4 FIG. is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM2 used in the examples.

[0063] Figure 5 It is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM3 used in the examples.

[0064] Figure 6 It is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM4 used in the examples.

[0065] Figure 7 It is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM5 used in the examples.

[0066] Figure 8 It is a DSC curve showing the results of differential scanning calorimetry of titanium oxyphthalocyanine CGM6 used in the examples.

[0067] Figure 9 It is a figure showing the measurement results of the X-ray diffraction spectrum of titanium oxyphthalocyanine CGM1 used in the examples.

[0068] Figure 10 It is a figure showing the calculation method of the calorific value and the full width at half maximum in the DSC curve. Detailed Embodiments

[0069] Hereinafter, the detailed embodiments of the electrophotographic photoreceptor according to the embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited by any of the following descriptions.

[0070] Figure 1 It is a schematic cross-sectional view showing an example of the electrophotographic photoreceptor according to the embodiments of the present invention, representing a negative charge type laminated electrophotographic photoreceptor.

[0071] As shown in the figure, in the negative charge type laminated photoreceptor, a base layer 2 and a photosensitive layer 5 having a charge generation layer 3 and a charge transport layer 4 are sequentially laminated on a conductive substrate 1, wherein the charge generation layer 3 has a charge generation function and the charge transport layer 4 has a charge transport function. In addition, the base layer 2 can also be provided as needed.

[0072] The photoreceptor according to the embodiments of the present invention at least includes a conductive substrate 1, a charge generation layer 3 provided on the conductive substrate 1 and containing a charge generation material, and a charge transport layer 4 containing a hole transport material, a resin binder, an electron transport material, and an inorganic oxide.

[0073] In the photoreceptor according to the embodiments of the present invention, the hole transport material contained in the charge transport layer 4 includes a compound having a structure represented by the following general formula (A-1). By using such a hole transport material, the photosensitive layer can obtain the effect of maintaining high sensitivity after rubbing resistance.

[0074]

[0075] (In formula (A-1), Re, Rf, Rg, and Ri each independently represent a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted styryl group; Rh represents a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted styryl group, or a structural unit represented by the following general formula (Rh1) or (Rh2); x and z represent integers from 0 to 4; j and y represent integers from 0 to 5; n represents an integer from 1 to 2; q represents an integer from 0 to 2; and r represents an integer from 0 to 1.)

[0076]

[0077] (In formulas (Rh1) and (Rh2), Rj, Rk, and Rm each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; t represents an integer from 0 to 5; s represents an integer from 0 to 1; and * represents a bonding site.)

[0078] As the hole transport material having the structure represented by the above general formula (A-1), the hole transport materials described in Tables 1 to 8 below can be preferably used, for example.

[0079] [Table 1]

[0080] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM1-1 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-2 - 0 - Me 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-3 - 0 - Me 1 m- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-4 - 0 - Me 1 o- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-5 - 0 - Et 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-6 - 0 - Et 1 m- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-7 - 0 - Et 1 o- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-8 - 0 - OMe 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-9 - 0 - OMe 1 m- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-10 - 0 - OMe 1 o- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-11 - 0 - OEt 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-12 - 0 - - - - - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-13 - 0 - - - - Me 1 o- 1 1 p- 0 Rh1 1 p- H HTM1-14 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-15 - 0 - Me 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-16 - 0 - Me 1 m- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-17 - 0 - Me 1 o- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-18 - 0 - Et 1 o- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-19 - 0 - OMe 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-20 - 0 - OEt 1 p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-21 - 0 - - - - - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-22 - 0 - - - - Me 1 o- 1 1 p- 0 Rh1 1 p- H HTM1-23 - 0 - Me 2 o-, p- - 0 - 1 1 m- 0 Rh1 1 p- H HTM1-24 - 0 - Me 2 o-, p- - 0 - 1 1 o- 0 Rh1 1 p- H HTM1-25 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Rh2 1 p- H HTM1-26 - 0 - Me 1 p- - 0 - 1 1 p- 0 Rh2 1 p- H

[0081] [Table 2]

[0082] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM1-27 - 0 - Et 1 o- - 0 - 1 1 p- 0 Rh2 1 p- H HTM1-28 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Rh2 1 p- H HTM1-29 - 0 - Me 1 p- - 0 - 1 1 p- 0 Rh2 1 p- H HTM1-30 - 0 - Et 1 o- - 0 - 1 1 p- 0 Rh2 1 p- H HTM1-31 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 Rh1 1 p- H HTM1-32 - 0 - - - - - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-33 - 0 - Me 2 o-, p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-34 - 0 - Me 1 p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-35 - 0 - Me 1 m- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-36 - 0 - Me 1 o- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-37 - 0 - Et 1 p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-38 - 0 - Et 1 m- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-39 - 0 - Et 1 o- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-40 - 0 - OMe 1 p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-41 - 0 - OMe 1 m- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-42 - 0 - OMe 1 o- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-43 - 0 - OEt 1 p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-44 - 0 - Me 2 o-, p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-45 - 0 - Me 1 p- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-46 - 0 - Me 1 m- - 0 - 1 2 p-, p- 0 Rh1 1 p- H HTM1-47 - 0 - Me 1 o- - 0 - 1 2 p-, p- 0 Rh1 1 p- H

[0083] [Table 3]

[0084] Number s Rj t Position Rk t Position Rm HTM1-1 1 - - - - - - - HTM1-2 1 - - - - - - - HTM1-3 1 - - - - - - - HTM1-4 1 - - - - - - - HTM1-5 1 - - - - - - - HTM1-6 1 - - - - - - - HTM1-7 1 - - - - - - - HTM1-8 1 - - - - - - - HTM1-9 1 - - - - - - - HTM1-10 1 - - - - - - - HTM1-11 1 - - - - - - - HTM1-12 1 - - - - - - - HTM1-13 1 - - - - - - - HTM1-14 1 Me 1 p- Me 1 p- - HTM1-15 1 Me 1 p- Me 1 p- - HTM1-16 1 Me 1 p- Me 1 p- - HTM1-17 1 Me 1 p- Me 1 p- - HTM1-18 1 Me 1 p- Me 1 p- - HTM1-19 1 Me 1 p- Me 1 p- - HTM1-20 1 Me 1 p- Me 1 p- - HTM1-21 1 Me 1 p- Me 1 p- - HTM1-22 1 Me 1 p- Me 1 p- - HTM1-23 1 - - - - - - - HTM1-24 1 - - - - - - - HTM1-25 1 - - - - - - H HTM1-26 1 - - - - - - H

[0085] [Table 4]

[0086] Number s Rj t Position Rk t Position Rm HTM1-27 1 - - - - - - H HTM1-28 1 - - - Me 1 p- - HTM1-29 1 - - - Me 1 p- - HTM1-30 1 - - - Me 1 p- - HTM1-31 1 - - - - - - - HTM1-32 1 - - - - - - - HTM1-33 1 - - - - - - - HTM1-34 1 - - - - - - - HTM1-35 1 - - - - - - - HTM1-36 1 - - - - - - - HTM1-37 1 - - - - - - - HTM1-38 1 - - - - - - - HTM1-39 1 - - - - - - - HTM1-40 1 - - - - - - - HTM1-41 1 - - - - - - - HTM1-42 1 - - - - - - - HTM1-43 1 - - - - - - - HTM1-44 1 Me 1 p- Me 1 p- - HTM1-45 1 Me 1 p- Me 1 p- - HTM1-46 1 Me 1 p- Me 1 p- - HTM1-47 1 Me 1 p- Me 1 p- -

[0087] [Table 5]

[0088] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM2-1 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 - - - ph HTM2-2 - 0 - Me 1 o- - 0 - 1 1 p- 0 - - - ph HTM2-3 - 0 - Me 1 m- - 0 - 1 1 p- 0 - - - ph HTM2-4 - 0 - Me 1 p- - 0 - 1 1 p- 0 - - - ph HTM2-5 - 0 - Et 1 o- - 0 - 1 1 p- 0 - - - ph HTM2-6 - 0 - Et 1 m- - 0 - 1 1 p- 0 - - - ph HTM2-7 - 0 - Et 1 p- - 0 - 1 1 p- 0 - - - ph HTM2-8 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 - - - ph HTM2-9 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 - - - ph HTM2-10 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 - - - ph HTM2-11 - 0 - Me 2 o-, p- Me 1 o- 1 1 p- 0 - - - ph HTM2-12 - 0 - Me 1 o- Me 1 o- 1 1 p- 0 - - - ph HTM2-13 - 0 - Me 1 p- Me 1 o- 1 1 p- 0 - - - ph HTM2-14 - 0 - - - - - 0 - 1 1 p- 0 - - - ph HTM2-15 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-16 - 0 - Me 1 o- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-17 - 0 - Me 1 m- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-18 - 0 - Me 1 p- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-19 - 0 - Et 1 o- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-20 - 0 - Et 1 m- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-21 - 0 - Et 1 p- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-22 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-23 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-24 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-25 - 0 - - - - - 0 - 1 1 p- 0 Me 1 p- -p-tolyl HTM2-26 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 m- -m-toly

[0089] [Table 6]

[0090] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM2-27 - 0 - Me 1 o- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-28 - 0 - Me 1 m- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-29 - 0 - Me 1 p- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-30 - 0 - Et 1 o- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-31 - 0 - Et 1 m- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-32 - 0 - Et 1 p- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-33 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-34 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-35 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-36 - 0 - - - - - 0 - 1 1 p- 0 Me 1 m- -m-tolyl HTM2-37 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 - - - H HTM2-38 - 0 - Me 1 o- - 0 - 1 1 p- 0 - - - H HTM2-39 - 0 - Me 1 m- - 0 - 1 1 p- 0 - - - H HTM2-40 - 0 - Me 1 p- - 0 - 1 1 p- 0 - - - H HTM2-41 - 0 - Et 1 o- - 0 - 1 1 p- 0 - - - H HTM2-42 - 0 - Et 1 m- - 0 - 1 1 p- 0 - - - H HTM2-43 - 0 - Et 1 p- - 0 - 1 1 p- 0 - - - H HTM2-44 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 - - - H HTM2-45 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 - - - H HTM2-46 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 - - - H HTM2-47 - 0 - Me 2 o-, p- Me 1 o- 1 1 p- 0 - - - H HTM2-48 - 0 - Me 1 o- Me 1 o- 1 1 p- 0 - - - H HTM2-49 - 0 - Me 1 p- Me 1 o- 1 1 p- 0 - - - H HTM2-50 - 0 - - - - - 0 - 1 1 p- 0 - - - H

[0091] [Table 7]

[0092] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM2-51 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 p- H HTM2-52 - 0 - Me 1 o- - 0 - 1 1 p- 0 Me 1 p- H HTM2-53 - 0 - Me 1 m- - 0 - 1 1 p- 0 Me 1 p- H HTM2-54 - 0 - Me 1 p- - 0 - 1 1 p- 0 Me 1 p- H HTM2-55 - 0 - Et 1 o- - 0 - 1 1 p- 0 Me 1 p- H HTM2-56 - 0 - Et 1 m- - 0 - 1 1 p- 0 Me 1 p- H HTM2-57 - 0 - Et 1 p- - 0 - 1 1 p- 0 Me 1 p- H HTM2-58 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 p- H HTM2-59 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 Me 1 p- H HTM2-60 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 Me 1 p- H HTM2-61 - 0 - - - - - 0 - 1 1 p- 0 Me 1 p- H HTM2-62 - 0 - Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 m- H HTM2-63 - 0 - Me 1 o- - 0 - 1 1 p- 0 Me 1 m- H HTM2-64 - 0 - Me 1 m- - 0 - 1 1 p- 0 Me 1 m- H HTM2-65 - 0 - Me 1 p- - 0 - 1 1 p- 0 Me 1 m- H HTM2-66 - 0 - Et 1 o- - 0 - 1 1 p- 0 Me 1 m- H HTM2-67 - 0 - Et 1 m- - 0 - 1 1 p- 0 Me 1 m- H HTM2-68 - 0 - Et 1 p- - 0 - 1 1 p- 0 Me 1 m- H HTM2-69 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 0 Me 1 m- H HTM2-70 Me 1 o- Me 1 o- - 0 - 1 1 p- 0 Me 1 m- H HTM2-71 Me 1 o- Me 1 p- - 0 - 1 1 p- 0 Me 1 m- H HTM2-72 - 0 - - - - - 0 - 1 1 p- 0 Me 1 m- H HTM2-73 - 0 - Me 2 o-, p- - 0 - 1 2 p-, p- 0 - - - ph HTM2-74 - 0 - Me 1 o- - 0 - 1 2 p-, p- 0 - - - ph HTM2-75 - 0 - Me 1 m- - 0 - 1 2 p-, p- 0 - - - ph HTM2-76 - 0 - Me 1 p- - 0 - 1 2 p-, p- 0 - - - ph HTM2-77 - 0 - Et 1 o- - 0 - 1 2 p-, p- 0 - - - ph

[0093] [Table 8]

[0094] Number Re x Position Rf y Position Rg z Position q n Position r Rh j Position Ri HTM2-78 - 0 - Et 1 m- - 0 - 1 2 p-, p- 0 - - - ph HTM2-79 - 0 - Et 1 p- - 0 - 1 2 p-, p- 0 - - - ph HTM2-80 Me 1 o- Me 2 o-, p- - 0 - 1 2 p-, p- 0 - - - ph HTM2-81 Me 1 o- Me 1 o- - 0 - 1 2 p-, p- 0 - - - ph HTM2-82 Me 1 o- Me 1 p- - 0 - 1 2 p-, p- 0 - - - ph HTM2-83 - 0 - Me 2 o-, p- Me 1 o- 1 2 p-, p- 0 - - - ph HTM2-84 - 0 - Me 1 o- Me 1 o- 1 2 p-, p- 0 - - - ph HTM2-85 - 0 - Me 1 p- Me 1 o- 1 2 p-, p- 0 - - - ph HTM2-86 - 0 - - - - - 0 - 1 2 p-, p- 0 - - - ph HTM2-87 - 0 - Me 2 o-, p- - 0 - 1 1 p- 1 - - - ph HTM2-88 - 0 - Me 1 o- - 0 - 1 1 p- 1 - - - ph HTM2-89 - 0 - Me 1 m- - 0 - 1 1 p- 1 - - - ph HTM2-90 - 0 - Me 1 p- - 0 - 1 1 p- 1 - - - ph HTM2-91 - 0 - Et 1 o- - 0 - 1 1 p- 1 - - - ph HTM2-92 - 0 - Et 1 m- - 0 - 1 1 p- 1 - - - ph HTM2-93 - 0 - Et 1 p- - 0 - 1 1 p- 1 - - - ph HTM2-94 Me 1 o- Me 2 o-, p- - 0 - 1 1 p- 1 - - - ph HTM2-95 Me 1 o- Me 1 o- - 0 - 1 1 p- 1 - - - ph HTM2-96 Me 1 o- Me 1 p- - 0 - 1 1 p- 1 - - - ph HTM2-97 - 0 - Me 2 o-, p- Me 1 o- 1 1 p- 1 - - - ph HTM2-98 - 0 - Me 1 o- Me 1 o- 1 1 p- 1 - - - ph HTM2-99 - 0 - Me 1 p- Me 1 o- 1 1 p- 1 - - - ph HTM2-100 - 0 - - - - - 0 - 1 1 p- 1 - - - ph HTM2-101 - 0 - Me 2 o-, p- - 0 - 1 1 m- 0 - - - ph HTM2-102 - 0 - Me 2 o-, p- - 0 - 1 1 m- 0 Me 1 p- -p-tolyl HTM2-103 - 0 - Me 2 o-, p- - 0 - 1 1 m- 0 - - - H HTM2-104 - 0 - Me 2 o-, p- - 0 - 1 1 m- 1 - - - ph

[0095] As the hole transporting material having the structure represented by the above general formula (A-1), the following hole transporting materials can be specifically exemplified.

[0096]

[0097]

[0098]

[0099]

[0100] The compounds having these structures can be synthesized by, for example, the method described in International Publication No. 2017 / 138566 or the method described in Japanese Patent Laid-Open No. 2000-66419, but are not limited thereto.

[0101] In addition, in the above compounds, the part containing a double bond may sometimes be a geometric isomer having a cis form - trans form, but may be either one or any case of a mixture. A plurality of the above structures may also be included.

[0102] Furthermore, in the photoreceptor according to an embodiment of the present invention, the charge generation material contained in the charge generation layer 3 has an exothermic peak at 251°C ± 5°C when the temperature increase condition is set to 20°C / minute in differential scanning calorimetry (DSC), the half-width at half-maximum of the exothermic peak is 15°C or less, the calorific value is 1.0 mJ / mg or more, and has a diffraction peak at 27.2° ± 0.3° in X-ray diffraction. The above calorific value is particularly preferably 1.0 mJ / mg or more and 10 mJ / mg or less. By using the oxotitanium phthalocyanine having such thermal characteristics in combination with the composition of the above photosensitive layer, the decrease amount of the potential holding rate during brushing can be reduced. In addition, it is considered that the large half-width at half-maximum reflects the disorder of the crystal structure. Therefore, it is considered that the above phthalocyanine has a small disorder of the crystal structure due to the small half-width at half-maximum, and as a result, the stability of the electrical characteristics can be improved.

[0103] As a method for producing oxotitanium phthalocyanine having such characteristics, it is particularly preferable to use phthalonitrile and titanium alkoxide as raw materials, an O-alkylisourea derivative as a base catalyst, and not to use orthodichlorobenzene, chloronaphthalene, or quinoline as a synthesis solvent. By such a production method, oxotitanium phthalocyanine showing an X-ray diffraction structure called the Y type and having characteristic thermal properties caused by minute differences in the crystal structure that can be confirmed by differential scanning calorimetry can be obtained. It is considered that by using this oxotitanium phthalocyanine, the effects of the present invention can be obtained. Specifically, the method described in Japanese Patent Application Laid-Open No. 2008-174677 can be cited, but it is not limited thereto.

[0104] Regarding the thermal properties of oxotitanium phthalocyanine, although there are descriptions in Japanese Patent Application Laid-Open Nos. 4-221961, 4-221962, and 2007-161992, there are differences in their heat generation peak temperatures, or there is no description regarding the calorific value or peak shape. In addition, because of differences in starting materials, synthesis solvents, etc., the effects such as those of the present invention cannot be obtained.

[0105] Differential scanning calorimetry can be performed, for example, by using DSC7020 manufactured by Hitachi High-Technologies Corporation (Hitachi High-Tech Science Corporation), raising the temperature from 20°C to 420°C under the condition of a heating rate of 20°C / minute, using a dedicated aluminum pan, and using a sample amount of 5 mg to 10 mg. Based on the obtained DSC curve, the baseline of the heat generation peak is taken, and the calorific value is obtained from the area of the heat generation part.

[0106] At this time, if the half-width at half-maximum of the heat generation peak is 15°C or less, it is more preferable from the viewpoint of the stability of electrical properties. The half-width at half-maximum can be obtained based on the temperature positions of two points that are 1 / 2 the height of the peak of the heat flow rate with respect to the baseline at the temperature showing the heat generation peak, before and after the peak position.

[0107] Based on Figure 10 , the starting temperature, ending temperature, and half-width at half-maximum of the heat generation peak in the DSC curve are described.

[0108] In the DSC curve, the DSC curve in the temperature region where no heat generation peak is observed is used as the baseline, the temperature of the point where the DSC curve deviates from the baseline on the low-temperature side (Ll) is taken as the starting temperature (Ts) of the heat generation peak, and the temperature of the point where the DSC curve deviates from the baseline on the high-temperature side (Lh) is taken as the ending temperature (Te) of the heat generation peak. The absolute amount is obtained as the calorific value from the area value of the region surrounded by the straight line (La) connecting the point corresponding to the temperature (Ts) and the point corresponding to the temperature (Te) on the DSC curve and the DSC curve.

[0109] In addition, the half-width at half-maximum is defined as follows. InFigure 10 Among them, a perpendicular line (Lb) is drawn from the vertex (P1) of the heat generation peak to the temperature axis, and the intersection point (P2) of the perpendicular line (Lb) and the above-mentioned straight line (La) is obtained. The midpoint between the intersection point (P2) and the above-mentioned vertex (P1) is taken as (P3). A straight line (Lc) passing through the midpoint (P3) and parallel to the straight line (La) is drawn. When the intersection points of the straight line (Lc) and the DSC curve are denoted as the low-temperature side intersection point (P4) and the high-temperature side intersection point (P5), the temperature difference (T2 - T1) between the temperature (T1) at the intersection point (P4) and the temperature (T2) at the intersection point (P5) is taken as the full width at half maximum.

[0110] In addition, in the photoreceptor according to the embodiment of the present invention, the masses of the hole transport material, resin binder, electron transport material, and inorganic oxide contained in the charge transport layer 4 satisfy the relationships shown in the following formulas 1 to 5. That is, when the mass of the hole transport material is denoted as a, the mass of the resin binder is denoted as b, the mass of the electron transport material is denoted as c, and the mass of the inorganic oxide is denoted as d, a, b, c, and d satisfy the conditions shown in the following formulas 1 to 5.

[0111] Formula 1: 1.5 ≤ b / a ≤ 5.7

[0112] Formula 2: 0.005 ≤ c / a ≤ 0.35

[0113] Formula 3: 0.05 ≤ d / a ≤ 0.70

[0114] Formula 4: a ≥ c + d

[0115] Formula 5: c / d ≥ 0.01

[0116] In Formula 1, when b / a is less than 1.5, the abrasion resistance during brushing may be insufficient. When b / a exceeds 5.7, the rise of the bright part potential during brushing becomes large.

[0117] In Formula 2, when c / a is less than 0.005, the ghosting on the image may deteriorate. When c / a exceeds 0.35, the charge stability may deteriorate.

[0118] In Formula 3, when d / a is less than 0.05, the abrasion resistance during brushing may be insufficient. When d / a exceeds 0.70, the film formation during brushing deteriorates.

[0119] Within the range where Formula 4 or Formula 5 is not satisfied, it may not be possible to sufficiently obtain the stability of the electrical characteristics during long-term use.

[0120] In the present invention, there are no particular limitations on points other than the above-mentioned constitution, and appropriate constitution can be carried out according to conventional methods.

[0121] (Conductive substrate)

[0122] The conductive substrate 1 functions as an electrode of the photoreceptor and at the same time serves as a support for each layer constituting the photoreceptor, and can have any shape such as cylindrical, plate-like, film-like, etc. As the material of the conductive substrate 1, metals such as aluminum, stainless steel, nickel, etc., or materials with conductive treatment on the surface of glass, resin, etc. can be used.

[0123] (Base layer)

[0124] The base layer 2 is a layer mainly composed of resin or a layer composed of a metal oxide film such as acid-resistant aluminum. The base layer 2 is provided as needed for the purpose of controlling the injectability of charges injected from the conductive substrate 1 into the photosensitive layer, covering the defects on the surface of the conductive substrate 1, improving the adhesiveness between the photosensitive layer and the conductive substrate 1, etc. As the resin material used for the base layer 2, insulating polymers such as casein, polyvinyl alcohol, polyamide, melamine, cellulose, etc., and conductive polymers such as polythiophene, polypyrrole, polyaniline, etc. can be cited, and these resins can be used alone or in appropriate combinations. In addition, these resins can also be used containing metal oxides such as titanium dioxide and zinc oxide.

[0125] (Charge generation layer)

[0126] The charge generation layer 3 contains a charge generation material that satisfies the above conditions and is formed by a method such as coating a coating liquid in which particles of the charge generation material are dispersed in a resin binder. The charge generation layer 3 receives light and generates charges. It is important for the charge generation layer 3 to have high charge generation efficiency and good injectability of the simultaneously generated charges into the charge transport layer 4, and it is expected to have small electric field dependence and good injection even at low electric fields.

[0127] As the charge generation material, oxytitanium phthalocyanine that satisfies the above conditions is used. In addition to this, phthalocyanine compounds such as X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, α-type oxytitanium phthalocyanine, β-type oxytitanium phthalocyanine, Y-type oxytitanium phthalocyanine having thermal properties different from those of the present invention, γ-type oxytitanium phthalocyanine, amorphous oxytitanium phthalocyanine, ε-type copper phthalocyanine, etc., various azo pigments, anthraquinone pigments, thiopyrylium pigments, perylene pigments, perynone pigments, squarylium pigments, quinacridone pigments, etc. can be appropriately combined and used as the charge generation material, and appropriate substances can be selected according to the light wavelength region of the exposure light source used for image formation. Particularly preferably, phthalocyanine compounds are used. The charge generation layer 3 can also use the charge generation material as the main body and add hole transport materials, charge transport materials, etc. for use.

[0128] As the resin binder of the charge generation layer 3, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, phenoxy resin, polyvinyl acetal resin, polyvinyl butyral resin, polystyrene resin, polysulfone resin, diallyl phthalate resin, polymers and copolymers of methacrylate resin, etc. can be appropriately used in combination.

[0129] In addition, the content of the charge generation material in the charge generation layer 3 is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, relative to the solid content in the charge generation layer 3. In addition, the content of the resin binder in the charge generation layer 3 is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, relative to the solid content in the charge generation layer 3.

[0130] The charge generation layer 3 only needs to have a charge generation function, so its thickness is generally 1 μm or less, preferably 0.5 μm or less.

[0131] (Charge transport layer)

[0132] The charge transport layer 4 contains the above-mentioned hole transport material, resin binder, electron transport material and inorganic oxide.

[0133] As the hole transport material, together with the hole transport material having the structure represented by the above general formula (A-1), other hole transport materials can be used in combination. As such other hole transport materials, hole transport materials containing an arylamine structure other than the hole transport material having the structure represented by the above general formula (A-1) can be appropriately used.

[0134] More specifically, as the above-mentioned other hole transport materials, arylamine compounds represented by the following structural formulas (II-1) to (II-31) are preferably used, but as long as it is a material showing hole transport properties, it is not limited thereto.

[0135]

[0136]

[0137]

[0138] As the resin binder for the charge transport layer 4, various polycarbonate resins such as polyarylate resin, bisphenol A type, bisphenol Z type, bisphenol C type, bisphenol A type-biphenyl copolymer, bisphenol Z type-biphenyl copolymer, etc. can be used alone or in combination. In addition, the same resin with different molecular weights can also be mixed and used. In addition, polyphenylene resin, polyester resin, polyvinyl acetal resin, polyvinyl butyral resin, polyvinyl alcohol resin, vinyl chloride resin, vinyl acetate resin, polyethylene resin, polypropylene resin, acrylic resin, polyurethane resin, epoxy resin, melamine resin, silicone resin, polyamide resin, polystyrene resin, polyacetal resin, polysulfone resin, polymers of methacrylate and their copolymers, etc. can be used.

[0139] In the GPC (gel permeation chromatography) analysis based on polystyrene conversion, the weight-average molecular weight of these other resins is preferably 5,000 to 250,000, more preferably 10,000 to 200,000.

[0140] As the resin binder for the charge transport layer 4, a resin binder preferably contains a resin having a viscosity conversion molecular weight (viscosity average molecular weight) of 15,000 or more, preferably 30,000 or more and 100,000 or less, more preferably 40,000 or more and 80,000 or less, and having a repeating unit represented by the following structural formula (BD-1). By using such a resin binder, high durability can be obtained in the photosensitive layer.

[0141]

[0142] (In formula (BD-1), R1 and R2 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, W represents a single bond, an oxygen atom, a sulfur atom or CR3R4, R3 and R4 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R3 and R4 may combine with each other to form a substituted or unsubstituted cycloalkyl group having 5 to 6 carbon atoms.)

[0143] As such a resin, resins represented by the following structural formulas CTB1 to CTB11 can be specifically exemplified, but are not limited thereto.

[0144]

[0145]

[0146] As the electron transport material for the charge transport layer 4, any one or more of the compounds represented by the following structural formulas (E-1) to (E-5) are preferably used.

[0147]

[0148] (In formulas (E-1), (E-2), (E-3) and (E-4), R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 16 、R 17 、R 18 、R 19 each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkenyl group having 2 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 14 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 8 carbon atoms which may have a substituent, and u represents an integer of 0 to 5;

[0149] In formula (E-5), R 14 and R 15 each independently represents an aryl group having 6 to 14 carbon atoms which may have at least one alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may have a phenylcarbonyl group, an aralkyl group having 7 to 20 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 8 carbon atoms which may have an alkylamino group, or a cycloalkyl group having 3 to 10 carbon atoms;

[0150] (The above selected groups may be substituted by one or more halogen atoms.)

[0151] As such an electron transport material, specifically, electron transport materials represented by the following structural formulas (ETM1-1) to (ETM5-5) can be preferably exemplified, but are not limited thereto.

[0152]

[0153]

[0154] As the inorganic oxide of the charge transport layer 4, there is no particular limitation, but it is preferably mainly composed of silicon dioxide, more preferably mainly composed of silicon dioxide, and contains 1 ppm or more and 2000 ppm or less, particularly 1 ppm or more and 1000 ppm or less of aluminum element. It is also preferable that the inorganic oxide is surface-treated with a silane coupling agent.

[0155] As the above silane coupling agent, a silane coupling agent having a structure represented by the following general formula (1) is preferably used.

[0156] (R 21 ) n -Si-(OR22 ) 4-n (1)

[0157] (In the formula, Si represents a silicon atom, R 21 represents an organic group in a form where carbon is directly bonded to the silicon atom, R 22 represents an organic group, and n represents an integer from 0 to 3.)

[0158] In addition, the above silane coupling agent preferably contains at least one selected from phenyltrimethoxysilane, vinyltrimethoxysilane, epoxytrimethoxysilane, methacrylic acid trimethoxysilane, aminotrimethoxysilane, ureidotrimethoxysilane, mercaptopropyltrimethoxysilane, isocyanatopropyltrimethoxysilane, phenylaminotrimethoxysilane, acrylic acid trimethoxysilane, p-styryltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0159] In addition, it is preferred that the inorganic oxide is surface-treated with a plurality of silane coupling agents, and the silane coupling agent initially used in the surface treatment has the structure represented by the above general formula (1).

[0160] In addition, the primary particle size of the inorganic oxide is preferably 1 to 200 nm.

[0161] By using such an inorganic oxide, mechanical strength can be imparted to the charge transport layer without an increase in aggregates in the charge transport layer.

[0162] As the film thickness of the charge transport layer 4, in order to maintain a practically effective surface potential, it is preferably in the range of 3 to 50 μm, more preferably in the range of 15 to 40 μm.

[0163] For the purpose of improving environmental resistance and stability against harmful light, antioxidants, light stabilizers, and other deterioration inhibitors may be contained in the above photosensitive layer as needed. Examples of compounds for such purposes include chromanol derivatives such as tocopherol and esterified compounds, polyarylalkane compounds, hydroquinone derivatives, etherified compounds, di-etherified compounds, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phenylenediamine derivatives, phosphonates, phosphites, phenolic compounds, hindered phenolic compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds, etc.

[0164] In addition, in order to improve the flatness of the formed film and impart lubricity, the photosensitive layer may contain a leveling agent such as silicone oil or fluorine oil. In addition to inorganic oxides surface-treated with silane coupling agents, the photosensitive layer may also contain metal oxides such as silica, titanium oxide, zinc oxide, calcium oxide, aluminum oxide, and zirconium oxide, metal sulfates such as barium sulfate and calcium sulfate, microparticles of metal nitrides such as silicon nitride and aluminum nitride, or fluorine resin particles such as tetrafluoroethylene resin, fluorine-based comb-grafted polymer resins, etc., in order to adjust the film hardness, reduce the friction coefficient, impart lubricity, etc. In addition, as required, other known additives may be contained within the range that does not significantly damage the electronic photography characteristics.

[0165] (Method for producing photoreceptor)

[0166] The method for manufacturing a photoreceptor according to an embodiment of the present invention includes: when manufacturing the above-mentioned electrophotographic photoreceptor, a charge generating layer coating liquid for forming the above-mentioned charge generating layer and a charge transport layer coating liquid for forming the above-mentioned charge transport layer are used, and a charge generating layer and a charge transport layer are formed by a dip coating method. By using the dip coating method, a photoreceptor with good appearance quality and stable electrical characteristics can be manufactured at low cost and while ensuring high productivity. When manufacturing the photoreceptor, there is no particular limitation on the points other than the use of the dip coating method, and it can be carried out according to a conventional method. The manufacturing method may also include a step of preparing a conductive substrate.

[0167] Specifically, for example, first, the charge generating material and any binder resin are dissolved and dispersed in a solvent to prepare a charge generating layer coating solution for forming a charge generating layer, and the charge generating layer coating solution is applied to the periphery of the conductive substrate via a base layer as required, and dried to form a charge generating layer. Next, the hole transport material and any resin binder, electron transport material, and inorganic oxide are dissolved in a solvent at a prescribed ratio to prepare a charge transport layer coating solution for forming a charge transport layer, and the charge transport layer coating solution is applied to the charge generating layer and dried to form a charge transport layer, thereby manufacturing a photoreceptor. Here, the type of solvent used in the preparation of the coating solution, the coating conditions, the drying conditions, etc. can be appropriately selected according to conventional methods without particular restrictions.

[0168] (Electronic Photographic Device)

[0169] The electrophotographic apparatus of the present invention is an apparatus equipped with the photoreceptor of the present invention described above, and can obtain desired effects by being applied to various device processes. Specifically, in charging processes such as contact charging using charging members such as rollers and brushes, non-contact charging using a corona tube, a scorotron, etc., and in developing processes such as contact development and non-contact development using non-magnetic single-component, magnetic single-component, two-component, etc. developing methods, sufficient effects can be obtained. In particular, in the case of a charging process having a contact charging method in which a charging member contacts the photoreceptor, the present invention is useful in terms of being able to suppress wear caused by the contact of the charging member.

[0170] Figure 2 A schematic structural diagram showing a configuration example of the electrophotographic apparatus of the present invention. The illustrated electrophotographic apparatus 60 of the present invention is equipped with the photoreceptor 8 of the present invention. The photoreceptor 8 of the present invention includes a conductive substrate 1, a base layer 2 covering the outer peripheral surface of the conductive substrate 1, and a photosensitive layer 300. The illustrated electrophotographic apparatus 60 is composed of a charging member 21 disposed at the outer peripheral edge of the photoreceptor 8, a high-voltage power supply 22 that supplies an applied voltage to the charging member 21, an image exposure member 23, a developing device 24 having a developing roller 241, a paper feeding member 25 having a paper feeding roller 251 and a paper feeding guide 252, and a transfer charger (direct charging type) 26. The electrophotographic apparatus 60 may further include a cleaning device 27 having a cleaning blade 271 and a charge removing member (not shown). In addition, the electrophotographic apparatus 60 of the present invention can be configured as a color printer.

[0171] Examples

[0172] Hereinafter, specific embodiments of the present invention will be further described in detail using examples. The present invention is not limited by the following examples within the scope of its technical content.

[0173] (Manufacture of negative charge layer laminated type photoreceptor)

[0174] (Example 1)

[0175] 3 parts by mass of alcohol-soluble nylon (manufactured by Toray Industries, Inc., trade name “CM8000”) and 7 parts by mass of amino-silane-treated titanium oxide fine particles were dissolved and dispersed in 80 parts by mass of methanol and 10 parts by mass of isopropyl alcohol to prepare a coating liquid 1. The coating liquid 1 was impregnated and coated on the outer periphery of an aluminum cylinder having an outer diameter of 30 mm as the conductive substrate 1, and dried at a temperature of 120° C. for 30 minutes to form a base layer 2 having a film thickness of 2 μm.

[0176] 2 parts by mass of CGM1 shown in the following table as a charge generation material (CGM) (oxotitanium phthalocyanine described in Example 1 of JP-A-2008-174677), 0.5 part by mass of polyvinyl butyral resin as a resin binder, namely, "S-LEC BM-2" manufactured by Sekisui Chemical Co., Ltd., and 0.5 part by mass of "S-LEC BX-L" were dissolved and dispersed in 80 parts by mass of methyl ethyl ketone to prepare Coating Liquid 2. This Coating Liquid 2 was impregnated and coated on the above-described base layer 2. It was dried at a temperature of 80°C for 30 minutes to form a charge generation layer 3 with a film thickness of 0.3 μm.

[0177] 4 parts by mass of the compound represented by the above formula HTM1-1 as a hole transport material (HTM), 16 parts by mass of a resin having a repeating unit represented by the above formula CTB1 as a resin binder (CTB) (viscosity-converted molecular weight: 55,000), and 0.1 part by mass of the compound represented by the above formula ETM1-1 as an electron transport material (ETM) were dissolved in 120 parts by mass of tetrahydrofuran.

[0178] Next, using silica YA050C (aluminum element content 900 ppm) manufactured by Admatechs Co., Ltd. as an inorganic oxide, the silica was surface-treated with phenyltrimethoxysilane as a surface treatment agent at a treatment amount of 0.8% by mass to prepare 1 part by mass of surface-treated surface-treated silica, which was dispersed in 10 parts by mass of tetrahydrofuran. The liquid in which the above hole transport material and the like were dissolved was added to and stirred in this silica dispersion liquid to prepare Coating Liquid 3.

[0179] This Coating Liquid 3 was impregnated and coated on the above-described charge generation layer 3 and dried at a temperature of 120°C for 60 minutes to form a charge transport layer 4 with a film thickness of 25 μm, thereby manufacturing a negatively charged laminated photoreceptor.

[0180] (Examples 2 to 47)

[0181] Based on the content described in Example 1, the composition was changed according to the conditions shown in the following table, and a photoreceptor was similarly manufactured.

[0182] In addition, as the inorganic oxide, the inorganic oxides shown in Table 9 below were used.

[0183] [Table 9]

[0184]

[0185] *1) Silica A: manufactured by Admatechs Co., Ltd., YA010C, primary particle size 10 nm

[0186] *2) Silica D: Manufactured by Yaduma Technology Co., Ltd., YA050C, primary particle size 50 nm

[0187] *3) Silica E: Manufactured by Yaduma Technology Co., Ltd., YA400C, primary particle size 100 nm

[0188] *4) Silica F: Silica with an aluminum content adjusted to 10 ppm according to the method described in the test example of Japanese Patent Laid-Open No. 2015-117138, primary particle size 100 nm

[0189] *5) Silica G: Silica with an aluminum content adjusted to 100 ppm according to the method described in the test example of Japanese Patent Laid-Open No. 2015-117138, primary particle size 100 nm

[0190] *6) Silica H: Silica with an aluminum content adjusted to 2000 ppm according to the method described in the test example of Japanese Patent Laid-Open No. 2015-117138, primary particle size 100 nm

[0191] *7) KBM573: Manufactured by Shin-Etsu Chemical Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane In addition, for the charge generation material (CGM), oxotitanium phthalocyanine shown in Table 10 below was used.

[0192] [Table 10]

[0193] Charge generation material Type Peak temperature (°C) Peak heat (mJ / mg) Half-peak width (°C) CGM1 Example 1 of Japanese Patent Laid-Open No. 2008-174677 250.7 3.36 13.2 CGM2 Example 2 of Japanese Patent Laid-Open No. 2008-174677 250.8 3.10 13.0 CGM3 Synthesis Example 3 of Japanese Patent Laid-Open No. 2000-239577 245.6 3.19 15.6 CGM4 Manufacturing Example 3 of Japanese Patent Laid-Open No. 2004-2874 248.9 0.86 11.8 CGM5 CG-01H manufactured by IT-chem Co., Ltd. 244.3 3.24 20.7 CGM6 TPL-3 manufactured by Orient Chemical Industries Co., Ltd. 233.6 4.52 17.1

[0194] <Differential Scanning Calorimetry (DSC)>

[0195] For each of the above oxotitanium phthalocyanines of CGM1 to CGM6, differential scanning calorimetry was performed. The differential scanning calorimetry was carried out by using DSC7020 manufactured by Hitachi High-Technologies Corporation, heating from 20 °C to 420 °C at a heating rate of 20 °C / minute, using a dedicated aluminum pan, and using a sample amount of 5 mg to 10 mg. The heat and the half-peak width were obtained as described above. The DSC curves of CGM1 to CGM6 are shown respectively in Figures 3 to 8 below.

[0196] <X-ray Diffraction>

[0197] In addition, X-ray diffraction measurement was performed on the phthalocyanine of the above CGM1. The measurement was carried out as follows.

[0198] After storing 0.3 g of the sample Y-type phthalocyanine at a temperature of 23 ± 1 °C and a relative humidity of 50 to 60% RH for 24 hours, it was set on the sample holder of an X-ray diffraction apparatus (D8 DISCOVER manufactured by Bruker Corporation), and the measurement was carried out.

[0199] The conditions of the measuring device are as described below.

[0200] Incident-side optical system: Light source: Output: 50 kV, 100 mA, Monochromator: Multilayer mirror, Beam size: 10 mm (H) × 1.0 mm (W)

[0201] Receiving-side optical system: 0.12° parallel plate collimator, Detector: Scintillation counter

[0202] Scanning conditions: Scanning speed: 3 degrees / minute, Step size: 0.02°, Starting angle 5.0°, Ending angle 35.0°

[0203] The X-ray diffraction pattern of the obtained CGM1 is shown in Figure 9 . In addition, all the phthalocyanine oxotitaniums shown in Table 10 above are highly sensitive phthalocyanine oxotitaniums having a peak at 2θ = 27.2 ± 0.3° in X-ray diffraction.

[0204] [Table 11]

[0205]

[0206] [Table 12]

[0207]

[0208] *) CTB3: Resin having the repeating unit shown by the above formula CTB3 (viscosity-converted molecular weight: 60,000).

[0209] CTB4: Resin having the repeating unit shown by the above formula CTB4 (viscosity-converted molecular weight: 60,000).

[0210] CTB6: Resin having the repeating unit shown by the above formula CTB6 (viscosity-converted molecular weight: 50,000).

[0211] CTB8: Resin having the repeating unit shown by the above formula CTB8 (viscosity-converted molecular weight: 30,000).

[0212] CTB11: Resin having the repeating unit shown by the above formula CTB11 (viscosity-converted molecular weight: 15,000).

[0213] CTB12: Resin having the repeating unit shown by the above formula CTB5 (viscosity-converted molecular weight: 14,000).

[0214] **) ETM6-1: Compound having the structure shown by the following structural formula.

[0215]

[0216] ETM6-2: A compound having the structure shown by the following structural formula.

[0217]

[0218] [Table 13]

[0219]

[0220] [Table 14]

[0221]

[0222] (Comparative Examples 1 - 17)

[0223] Based on the content described in Example 1, the composition was changed according to the conditions shown in the following table, and the photoreceptor was produced in the same manner.

[0224] [Table 15]

[0225]

[0226] [Table 16]

[0227]

[0228] >[Evaluation of Photoreceptor]

[0229] The electrical properties of the photoreceptors prepared in Examples 1 - 47 and Comparative Examples 1 - 17 above were evaluated by the following method. The evaluation results are shown together in the following table.

[0230] >[Electrical Properties]

[0231] For the photoreceptors obtained in each example and comparative example, the electrical properties were evaluated using a processing simulator (CYNTHIA91) manufactured by Genentech Co., Ltd. by the following method.

[0232] For the photoreceptors of Examples 1 - 47 and Comparative Examples 1 - 17, in an environment of temperature 22°C and humidity 50%, the surface of the photoreceptor was charged to -650 V by corona discharge in the dark, and the surface potential V0 just after charging was measured. Then, after leaving it in the dark for 5 seconds, the surface potential V5 was measured, and according to the following calculation formula (2), the potential retention rate Vk5 (%) after 5 seconds of charging was obtained.

[0233] Vk5 = V5 / V0 × 100 (2)

[0234] Next, using a halogen lamp as a light source, it was spectrally separated by a filter to 780 nm to obtain 1.0 μW / cm 2The exposure light is irradiated onto the photoreceptor for 5 seconds starting from when the surface potential reaches -600 V, and the exposure amount required to attenuate the light until the surface potential reaches -300 V is denoted as E1 / 2 (μJ / cm 2 ), and evaluation was carried out.

[0235] Before and after the print evaluation shown in the following actual machine characteristics, the above electrical characteristics were measured respectively, and the change amounts ΔVk5 (change amount of potential retention rate) and ΔE1 / 2 (change amount of sensitivity) of the values after printing in the actual machine relative to the values before printing were obtained and compared.

[0236] <Actual Machine Characteristics>

[0237] The photoreceptors produced in Examples 1 to 47 and Comparative Examples 1 to 17 were mounted on a digital copying machine (manufactured by Canon Inc., image RUNNER ADVANCE C5030), and the film reduction amount before and after printing 40,000 sheets was evaluated as an index of abrasion resistance. Specifically, the film thicknesses of the photoreceptor before and after printing were measured, the difference was obtained, and the average wear amount (μm) after printing was evaluated.

[0238] In addition, as an evaluation of image defects, a halftone image was printed at the initial stage and after printing 40,000 sheets, and the white dot defects on the halftone and the film formation on the corresponding photoreceptor were observed. The case where there are no defects in the printed image and no toner adheres to the photoreceptor is denoted as ○, and the case where there are white dot defects on the halftone and toner adheres to the image defect corresponding part on the photoreceptor is denoted as ×.

[0239] The results thereof are summarized in the following table.

[0240] [Table 17]

[0241]

[0242] [Table 18]

[0243]

[0244] [Table 19]

[0245]

[0246] From the results in the above table, it can be seen that the photoconductors of Examples 1 to 47 have good abrasion resistance and no film formation, and the image quality is good both initially and after printing 40,000 sheets. As a photoconductor, the decrease in the potential holding rate is particularly small, and the electrical characteristics are good. On the other hand, in the photoconductors of Comparative Examples 1 to 17, the film wear amount after brush resistance is large, or film formation occurs in the photoconductor, and a decrease in the potential holding rate is also confirmed. In the photoconductors of Examples 1 to 47, although the principle is not very clear, it can be seen that by using a hole transport material and a charge generation material having a specific structure, the abrasion resistance, film formation resistance, and electrical characteristics can be improved.

[0247] From the above, it can be confirmed that by forming a photosensitive layer that satisfies the conditions of the present invention, an electrophotographic photoconductor that suppresses wear, has no film formation, and has excellent potential holding rate even during brush resistance can be obtained.

[0248] Symbol Explanation

[0249] 1 Conductive substrate

[0250] 2 Base layer

[0251] 3 Charge generation layer

[0252] 4 Charge transport layer

[0253] 5 Photosensitive layer

[0254] 8 Photoconductor

[0255] 21 Charging member

[0256] 22 High-voltage power supply

[0257] 23 Image exposure member

[0258] 24 Developing device

[0259] 241 Developing roller

[0260] 25 Paper feeding member

[0261] 251 Paper feeding roller

[0262] 252 Paper feeding guide

[0263] 26 Transfer charger (direct charging type)

[0264] 27 Cleaning device

[0265] 271 Cleaning blade

[0266] 60 Electrophotographic apparatus

[0267] 300 Photosensitive layer.

Claims

1. An electrophotographic photoreceptor, which is an electrophotographic photoreceptor comprising at least a conductive substrate and a photosensitive layer provided on the conductive substrate and sequentially having a charge generation layer and a charge transport layer, wherein, The charge transport layer contains a hole transport material, a resin binder, an electron transport material, and an inorganic oxide, and the charge generation layer contains a charge generation material. When the mass of the hole transport material contained in the charge transport layer is denoted as a, the mass of the resin binder is denoted as b, the mass of the electron transport material is denoted as c, and the mass of the inorganic oxide is denoted as d, a, b, c, and d satisfy the conditions shown in the following Formulas 1 to 5. Formula 1: 1.5 ≤ b / a ≤ 5.7 Formula 2: 0.005 ≤ c / a ≤ 0.35 Formula 3: 0.05 ≤ d / a ≤ 0.70 Formula 4: a ≥ c + d Formula 5: c / d ≥ 0.01 The hole transport material contains a compound having a structure represented by the following general formula (A-1), and the charge generation material contains oxotitanium phthalocyanine in which the heat generation peak when the temperature rising condition in differential scanning calorimetry is set to 20 °C / minute is at 251 °C ± 5 °C, the half-peak width of the heat generation peak is 15 °C or less, the calorific value is 1.0 mJ / mg or more, and there is a diffraction peak at 27.2° ± 0.3° in X-ray diffraction. In Formula (A-1), Re and Rg each independently represent a hydrogen atom or a branched alkyl group having 1 to 6 carbon atoms, Rf each independently represents a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, Ri each independently represents a hydrogen atom or a substituted or unsubstituted phenyl group, Rh represents a hydrogen atom, a branched alkyl group having 1 to 6 carbon atoms, or a structural unit represented by the following general formula (Rh1) or (Rh2), x and z represent integers from 0 to 4, j and y represent integers from 0 to 5, n represents an integer from 1 to 2, q represents an integer from 0 to 2, and r represents an integer from 0 to 1. In Formulas (Rh1) and (Rh2), Rj and Rk each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, Rm represents a hydrogen atom, t represents an integer from 0 to 5, s represents an integer from 0 to 1, and * represents a bonding site.

2. The electrophotographic photoreceptor according to claim 1, wherein, The electron transport material contains any one or more of the compounds represented by the following structural formulas (E-1) to (E-5). In formulas (E-1), (E-2), (E-3) and (E-4), R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 16 , R 17 , R 18 , R 19 each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkenyl group having 2 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 14 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 8 carbon atoms which may have a substituent, and u represents an integer of 0 to 5; In formula (E-5), R 14 and R 15 each independently represents an aryl group having 6 to 14 carbon atoms that may have at least one alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms that may have a phenylcarbonyl group, an aralkyl group having 7 to 20 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 8 carbon atoms that may have an alkylamino group, or a cycloalkyl group having 3 to 10 carbon atoms; The above-selected groups may be substituted by one or more halogen atoms.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein, The resin binder contains a resin having a viscosity-converted molecular weight of 15,000 or more and having a repeating unit represented by the following structural formula (BD-1). In Formula (BD-1), R1 and R2 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, W represents a single bond, an oxygen atom, a sulfur atom, or CR3R4, R3 and R4 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R3 and R4 may combine with each other to form a substituted or unsubstituted cycloalkyl group having 5 to 6 carbon atoms.

4. The electrophotographic photoreceptor according to claim 1 or 2, wherein, The inorganic oxide has silica as the main component, contains 1 ppm or more and 2000 ppm or less of aluminum element, and is surface-treated with a silane coupling agent having a structure represented by the following general formula (1). (R 21 ) n -Si-(OR 22 ) 4-n (1) In the formula, Si represents a silicon atom, and R 21 represents an organic group in which carbon is directly bonded to the silicon atom, and R 22 represents an organic group, and n represents an integer from 0 to 3.

5. The electrophotographic photoreceptor according to claim 4, wherein, The silane coupling agent includes at least one selected from phenyltrimethoxysilane, vinyltrimethoxysilane, epoxytrimethoxysilane, methacrylic acid trimethoxysilane, aminotrimethoxysilane, ureidotrimethoxysilane, mercaptopropyltrimethoxysilane, isocyanatopropyltrimethoxysilane, phenylaminotrimethoxysilane, acrylic acid trimethoxysilane, p-styryltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

6. The electrophotographic photoreceptor according to claim 4, wherein, The inorganic oxide is surface-treated with a variety of the silane coupling agents, and the silane coupling agent initially used in the surface treatment has the structure represented by the general formula (1).

7. A method for manufacturing an electrophotographic photoreceptor, which comprises: When manufacturing the electrophotographic photoreceptor according to any one of claims 1 to 6, a coating liquid for a charge generation layer for forming the charge generation layer and a coating liquid for a charge transport layer for forming the charge transport layer are used, and the steps of forming the charge generation layer and the charge transport layer by dip coating method.

8. An electrophotographic apparatus, which is formed by mounting the electrophotographic photoreceptor according to any one of claims 1 to 6.

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