Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus

Abstract

To provide an electrophotographic photoreceptor which suppresses an increase in dark decay during long-term repeated use in a high-temperature high-humidity environment and contributes to formation of high-quality images, a process cartridge employing the electrophotographic photoreceptor, and an electrophotographic device.SOLUTION: An electrophotographic photoreceptor is provided, comprising a support material, a first intermediate layer, a second intermediate layer, and a photosensitive layer arranged in the described order, the first intermediate layer containing a binder resin and carbon black while the second intermediate layer containing the binder resin and a specific perinone compound. A process cartridge having the electrophotographic photoreceptor, and an electrophotographic device are also provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic photosensitive member, a process cartridge including the electrophotographic photosensitive member, and an electrophotographic apparatus including the electrophotographic photosensitive member. [Background technology]

[0002] Electrophotographic photoreceptors containing organic photoconductive materials (charge-generating materials) are widely used in electrophotographic devices. In recent years, there has been a demand for suppressing potential fluctuations in electrophotographic photoreceptors during repeated use in order to increase the speed of electrophotographic devices and suppress fluctuations in image density during repeated use.

[0003] As a technology for suppressing potential fluctuations during repeated use, a technology for incorporating metal oxide particles into the undercoat layer of an electrophotographic photoreceptor is known. However, from the viewpoint of recycling of the electrophotographic photoreceptor, a configuration that does not incorporate metal oxide particles is more advantageous. Therefore, electrophotographic photoreceptors in which each layer on a support is composed only of organic materials have attracted attention.

[0004] As an electrophotographic photoreceptor having such a layer structure, Patent Document 1 discloses a technique in which an intermediate layer containing carbon black and an undercoat layer containing an organic electron transport compound are laminated together. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-060928 Summary of the Invention [Problem to be solved by the invention]

[0006] However, electrophotographic photoreceptors having a laminated intermediate layer containing carbon black and an undercoat layer containing an organic electron transport compound have room for improvement as described below. That is, when used repeatedly for a long period of time in a high-temperature, high-humidity environment, which is a harsh usage environment for electrophotographic photoreceptors, deterioration of image quality may occur due to increased dark decay. More specifically, increased dark decay may cause a fogging phenomenon in non-image areas, i.e., a phenomenon in which toner is developed in areas where the charging potential is reduced, and there is room for further improvement.

[0007] An object of the present invention is to provide an electrophotographic photosensitive member that suppresses an increase in dark attenuation during long-term repeated use in a high-temperature, high-humidity environment and contributes to the formation of high-quality images, a process cartridge equipped with the electrophotographic photosensitive member, and an electrophotographic apparatus equipped with the electrophotographic photosensitive member. [Means for solving the problem]

[0008] The above object can be achieved by the present invention described below. That is, an electrophotographic photoreceptor according to one aspect of the present invention is an electrophotographic photoreceptor having a support, a first intermediate layer, a second intermediate layer, and a photosensitive layer in this order, characterized in that the first intermediate layer contains a binder resin and carbon black, and the second intermediate layer contains a binder resin and at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (1) and perinone compounds represented by the following formula (2): [ka] [ka] (R in Equation (1) 11 ~R 18 and R in formula (2) 21 ~R 28each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, or R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 , and R 25 ~R 28 In each group, adjacent groups may be linked to form a ring.

[0009] Furthermore, a process cartridge according to another aspect of the present invention is characterized in that it integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to the main body of the electrophotographic apparatus.

[0010] Furthermore, an electrophotographic apparatus according to still another aspect of the present invention comprises the above electrophotographic photosensitive member, as well as a charging unit, an exposing unit, a developing unit, and a transferring unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electrophotographic photoreceptor that suppresses an increase in dark decay during repeated use over a long period of time under a high-temperature, high-humidity environment, and that contributes to the formation of high-quality images. Furthermore, according to the present invention, it is possible to provide a process cartridge including the electrophotographic photoreceptor, and an electrophotographic apparatus including the electrophotographic photoreceptor. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic view showing an example of a layer structure of an electrophotographic photoreceptor according to the present invention. [Figure 2] 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The electrophotographic photoreceptor according to the present invention comprises, in this order, a support, a first intermediate layer, a second intermediate layer, and a photosensitive layer. The first intermediate layer contains a binder resin and carbon black. The second intermediate layer contains a binder resin and at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (1) and perinone compounds represented by the following formula (2). [ka] [ka] (R in Equation (1) 11 ~R 18 and R in formula (2) 21 ~R 28 each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, or R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 , and R 25 ~R 28 In each group, adjacent groups may be linked to form a ring.

[0014] The present inventors speculate as follows about the mechanism by which the electrophotographic photoreceptor according to the present invention solves the above problems. It is presumed that blocking properties against holes, which are one cause of dark decay, can be improved to some extent by improving the electron transport compound and other ingredients contained in the layers constituting the electrophotographic photosensitive member, binder resin, etc. However, there is a limit to how much blocking properties can be improved by these improvements alone, and it was thought that in order to achieve further improvement, it would be necessary to improve the blocking properties from a different, new perspective.

[0015] Therefore, the present inventors have conducted research from a new perspective, aiming to further improve blocking properties by improving the interaction between two adjacent layers, rather than just improving a single layer. As a result, they have found that blocking properties can be significantly improved by laminating the following two intermediate layers. One of the two intermediate layers contains at least one perinone compound selected from the group consisting of perinone compounds represented by formula (1) and perinone compounds represented by formula (2), and the other contains carbon black.

[0016] Although the reason for this is unclear, the present inventors speculate that this is because the transfer of holes from the carbon black to the perinone compound is difficult at the interface between the two intermediate layers. In other words, the present inventors speculate that the significant improvement is achieved by combining the effects of the blocking properties of the bulk of the intermediate layer and the blocking properties at the interface between the two intermediate layers.

[0017] Furthermore, it was found that the blocking property due to the bulk of the intermediate layer is easily changed by repeated use over a long period of time, which is one of the causes of an increase in dark decay, whereas the blocking property due to the interaction at the interface between the two intermediate layers hardly changes even with repeated use over a long period of time. For this reason, the inventors speculate that they have been able to obtain an electrophotographic photoreceptor that can sufficiently suppress an increase in dark decay even with repeated use over a long period of time, and that can contribute to the formation of high-quality images.

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Electrophotographic photoreceptor] The electrophotographic photoreceptor according to the present invention has a support, a first intermediate layer, a second intermediate layer, and a photosensitive layer in this order. FIG. 1 is a diagram showing an example of the layer structure of an electrophotographic photosensitive member according to the present invention. 1, a first intermediate layer 102, a second intermediate layer 103, a charge generation layer 104, a charge transport layer 105, and a protective layer 106 are laminated in this order on a support 101. The charge generation layer 104 and the charge transport layer 105 are collectively referred to as a photosensitive layer 107. The support and each layer will be described below.

[0019] <Support> The support is preferably conductive (conductive support), and examples thereof include supports made of metals such as aluminum, iron, copper, gold, stainless steel, and nickel, and supports having a conductive coating on the surface of a metal or insulating material. Examples of insulating materials include plastics such as polyester resin, polycarbonate resin, and polyimide resin, glass, and paper. Examples of conductive coatings include thin metal films such as aluminum, chromium, silver, and gold; thin films of conductive materials such as indium oxide, tin oxide, and zinc oxide; and thin films of conductive ink containing silver nanowires.

[0020] The shape of the support may be, for example, a cylindrical shape or a film shape. Among these, a cylindrical aluminum support is superior in terms of mechanical strength, electrophotographic properties, and cost. A raw tube may be used as the support as is, but the surface of the raw tube may be subjected to physical treatments such as cutting, honing, and blasting, anodizing, or a chemical treatment using an acid or the like, in order to improve electrical properties and suppress interference fringes, and then the resulting support may be used.

[0021] <The first middle class> The electrophotographic photoreceptor according to the present invention has a first intermediate layer on a support, which makes it possible to conceal scratches and irregularities on the support surface and to control light reflection on the support surface. The first intermediate layer contains carbon black and a binder resin.

[0022] The DBP oil absorption of carbon black is 45 cm 3 / 100g or less is preferable, 40cm 3 It is more preferable that the amount is 100g or less.

[0023] When carbon black contains a large amount of impurities or has many functional groups on its surface, the resistance at the interface between the binder resin and the carbon black increases. Therefore, to achieve the volume resistivity required for the first intermediate layer, the loading amount of carbon black must be increased, but as a result, the carbon black particles tend to aggregate. For this reason, the ash content of the carbon black is preferably 0.1% or less, more preferably 0.05% or less. Furthermore, the pH of the carbon black is preferably 6.0 or more, more preferably 9.0 or more.

[0024] The number average primary particle size (D1) of the carbon black is preferably 200 nm or more and 500 nm or less.

[0025] The carbon black content in the first intermediate layer is preferably 0.5% by mass or more and 30% by mass or less, based on the total mass of the first intermediate layer. By including carbon black in such a proportion, hole blocking properties are improved, and the effect of suppressing an increase in dark decay is more likely to be achieved. The present inventors speculate that this is because favorable interaction with the perinone compound occurs more easily at the interface with the second intermediate layer.

[0026] Furthermore, by including carbon black in the first intermediate layer in a proportion of 30% by mass or less relative to the total mass of the first intermediate layer, contact between carbon black particles can be prevented, which in turn prevents localized concentration of electric field strength due to conductive paths and maintains leak resistance.

[0027] The binder resin is preferably a polyurethane resin or a phenol resin. The first intermediate layer may further contain silicone oil, resin particles, and the like.

[0028] The thickness of the first intermediate layer is preferably 3.0 μm or more and 50 μm or less, more preferably 5.0 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 35 μm or less.

[0029] The first intermediate layer can be formed by preparing a coating solution for the first intermediate layer containing the above-mentioned materials and solvent, forming a coating film from this, and then drying it. Examples of solvents used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of dispersion methods for dispersing carbon black in the coating solution for the first intermediate layer include methods using a paint shaker, sand mill, ball mill, and liquid collision-type high-speed disperser.

[0030] The volume resistivity of the first intermediate layer is 10 5 Ω cm or more 10 12 It is preferable that the volume resistivity of the first intermediate layer is 10 Ω·cm or less. 12 If the volume resistivity of the first intermediate layer is 10 Ω·cm or less, the flow of charge is less likely to be impeded during image formation, the residual potential is less likely to increase, and fluctuations in the dark potential and the light potential are less likely to occur. 5 If the resistivity is Ω·cm or more, the amount of charge that flows locally in the first intermediate layer when the electrophotographic photosensitive member is charged can be suppressed, making it difficult for leakage to occur.

[0031] The volume resistivity of the first intermediate layer is 10 6 Ω cm or more 10 10 It is more preferable that the resistivity is Ω·cm or less.

[0032] <The second middle class> The electrophotographic photoreceptor according to the present invention has a second intermediate layer on the first intermediate layer. By having the second intermediate layer on the first intermediate layer, the adhesion function between the layers is enhanced, and the electrical properties are improved. The second intermediate layer contains a perinone compound and a binder resin.

[0033] The perinone compound contained in the second intermediate layer is at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (1) and perinone compounds represented by the following formula (2). [ka] [ka] (R in Equation (1) 11 ~R 18 and R in formula (2) 21 ~R 28 each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, or R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 , and R 25 ~R 28 In each group, adjacent groups may be linked to form a ring.

[0034] In formula (1) and formula (2), examples of the substituent that the alkyl group may have include a halogen atom, an aryl group, and an alkoxycarbonyl group.

[0035] In addition, examples of the substituent that the aryl group may have include a halogen atom, an alkyl group, and an alkoxycarbonyl group. The aryl group is preferably an aryl group having 6 to 10 carbon atoms, and particularly preferably a phenyl group.

[0036] Examples of the substituent that the aryloxy group may have include a halogen atom, an alkyl group, and an alkoxycarbonyl group. The aryloxy group is preferably an aryloxy group having 6 to 10 carbon atoms, and particularly preferably a phenyloxy group.

[0037] Examples of the substituent that the alkoxycarbonyl group may have include a halogen atom and an aryl group. As the alkoxycarbonyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms is preferred, and a methoxycarbonyl group, an ethoxycarbonyl group, and a propoxycarbonyl group are particularly preferred.

[0038] R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 , and R 25 ~R 28 In each group, when adjacent groups are linked to each other to form a ring, it is particularly preferred that they form an aromatic ring, and a naphthalene ring or an anthracene ring is particularly preferred as the aromatic ring.

[0039] The alkyl group is preferably a linear or branched alkyl group having from 1 to 10 atoms in the main chain. In particular, from the viewpoints of improving hole blocking properties and suppressing an increase in dark attenuation, a branched alkyl group having from 3 to 10 carbon atoms is preferred. Specifically, the second intermediate layer preferably contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (3) and perinone compounds represented by the following formula (4): [ka] [ka] (R in Equation (3) 31 and R 32 , and R in formula (4) 41 and R 42 each independently represents a branched alkyl group having 3 to 10 carbon atoms.

[0040] Furthermore, it is more preferable that the second intermediate layer contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (5) and perinone compounds represented by the following formula (6): [ka] [ka] (R in Equation (5) 51 ~R 56 and R in formula (6) 61 ~R 66 each independently represents a methyl group, an ethyl group, or a propyl group.

[0041] As specific examples of the perinone compounds contained in the second intermediate layer, the structures of perinone compounds (1-1) to (1-17) and perinone compounds (2-1) to (2-17) are shown below, but the present embodiment is not limited thereto.

[0042] [ka] [ka]

[0043] The content of at least one perinone compound selected from the group consisting of perinone compounds represented by formula (1) and perinone compounds represented by formula (2) in the second intermediate layer is preferably 30% by mass to 70% by mass, based on the total mass of the second intermediate layer. When the second intermediate layer contains the perinone compound in such a proportion, the hole blocking ability is improved, and the effect of suppressing an increase in dark decay is more likely to be achieved. The present inventors speculate that this is because the interaction between carbon black and the perinone compound at the interface between the first and second intermediate layers is more likely to occur favorably.

[0044] Furthermore, when the content of the perinone compound in the second intermediate layer relative to the total mass of the second intermediate layer is X% by mass, and the content of carbon black in the first intermediate layer relative to the total mass of the first intermediate layer is Y% by mass, X / Y is preferably 2 to 12. By achieving such a ratio, hole blocking is improved, and the effect of suppressing an increase in dark decay is more likely to be achieved. The inventors speculate that this is because the interaction between the carbon black and the perinone compound at the interface between the first and second intermediate layers is more likely to occur favorably.

[0045] The second intermediate layer contains a binder resin, which may be a cured product obtained by polymerizing a monomer having a polymerizable functional group.

[0046] Examples of binder resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinylphenol resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide resins, polyamic acid resins, polyimide resins, polyamideimide resins, and cellulose resins.

[0047] Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0048] The second intermediate layer may further contain an electron transporting material or the like for the purpose of improving electrical properties. Examples of electron transport substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, aryl halide compounds, silole compounds, and boron-containing compounds. The second intermediate layer may be formed as a cured film by using an electron transport substance having a polymerizable functional group as the electron transport substance and copolymerizing it with the above-mentioned monomer having the polymerizable functional group.

[0049] The second intermediate layer can be formed by preparing a coating liquid for the second intermediate layer containing the above-mentioned materials and solvent, forming this coating film on the first intermediate layer, and then drying and / or curing the coating film.

[0050] Examples of the solvent used in the coating liquid for the second intermediate layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, halogenated aliphatic hydrocarbons, and aromatic compounds. Of these, the solvents preferably used in the present invention are alcohol-based solvents and ketone-based solvents.

[0051] Examples of dispersion methods for preparing the second intermediate layer coating liquid include methods using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, and a liquid collision type high-speed disperser.

[0052] The thickness of the second intermediate layer is preferably 0.05 μm or more and 50 μm or less, and more preferably 0.3 μm or more and 25 μm or less.

[0053] <Photosensitive layer> The photosensitive layer of an electrophotographic photoreceptor may be either (1) a multi-layer photosensitive layer or (2) a single-layer photosensitive layer. (1) The multi-layer photosensitive layer is a photosensitive layer having a configuration in which a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance are arranged in that order in the thickness direction. (2) The single-layer photosensitive layer is a photosensitive layer containing a charge generation substance and a charge transport substance in a single layer.

[0054] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generating layer and a charge transport layer.

[0055] (1-1) Charge generation layer The charge generating layer contains a charge generating material and a resin.

[0056] Examples of charge-generating materials include azo compounds, perylene compounds, polycyclic quinone compounds, indigo compounds, and phthalocyanine compounds. Among these, azo compounds and phthalocyanine compounds are preferred. Among phthalocyanine compounds, titanyl phthalocyanine compounds, chlorogallium phthalocyanine compounds, and hydroxygallium phthalocyanine compounds are more preferred. The content of the charge generating material in the charge generating layer is preferably 40% by mass or more and 85% by mass or less, and more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generating layer.

[0057] Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, and polyvinyl chloride resin.

[0058] The charge generating layer may further contain additives such as an antioxidant and an ultraviolet absorber, etc. Specific examples of the additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0059] The charge generating layer can be formed by preparing a coating solution for the charge generating layer containing the above-mentioned materials and solvent, forming the coating film on the second intermediate layer, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0060] The thickness of the charge generating layer is preferably from 0.01 μm to 5 μm, and more preferably from 0.15 μm to 0.4 μm.

[0061] (1-2) Charge transport layer The charge transport layer is obtained by dispersing a charge transport material and, if necessary, a binder resin in a solvent to prepare a coating liquid for the charge transport layer, forming a coating film of the coating liquid for the charge transport layer, and then drying the coating film.

[0062] Examples of charge transport materials include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. The charge transport material may also be a polymer having a group derived from any of these compounds in the main chain or side chain.

[0063] Among these, triarylamine compounds, styryl compounds, and benzidine compounds are preferred as charge transport materials, and triarylamine compounds are particularly preferred. The charge transport materials can be used singly or in combination of two or more.

[0064] Examples of binder resins used in the charge transport layer include resins (insulating resins) such as polyvinyl butyral resin, polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, polyvinyl acetate resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyamide resin, polyvinylpyridine resin, cellulose-based resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin.

[0065] As the binder resin used in the charge transport layer, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene can also be used.

[0066] Among these, polycarbonate resins and polyarylate resins are preferred as binder resins.

[0067] The binder resin may be used alone or in combination of two or more types as a mixture or copolymer. The copolymerization form may be any of block copolymer, random copolymer, alternating copolymer, etc. The weight average molecular weight (Mw) of the copolymer is preferably in the range of 10,000 to 300,000.

[0068] The content of the charge transport material in the charge transport layer is preferably 20% by mass to 80% by mass, more preferably 30% by mass to 60% by mass, based on the total mass of the charge transport layer. There is no limitation to the thickness of the charge transport layer, but it is preferably 5 μm or more and 40 μm or less.

[0069] (2) Single-layer photosensitive layer The single-layer photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating material, a charge transport material, a resin, and a solvent, forming the coating film on the second intermediate layer, and drying it. The charge generating material, charge transport material, and resin are the same as those exemplified in "(1) Multilayer Photosensitive Layer" above.

[0070] <Protective layer> A protective layer may be provided on the photosensitive layer as needed. The protective layer can be obtained by dissolving a resin in an organic solvent to prepare a coating solution for the protective layer, forming a coating film of the coating solution for the protective layer, and then drying the coating film. The protective layer can also be formed by curing the coating film with heat, electron beams, ultraviolet rays, or the like.

[0071] Examples of resins used in the protective layer include polyvinyl butyral resin, polyester resin, polycarbonate resin (polycarbonate Z resin, modified polycarbonate resin, etc.), nylon resin, polyimide resin, polyarylate resin, polyurethane resin, styrene-butadiene copolymer, styrene-acrylic acid copolymer, and styrene-acrylonitrile copolymer.

[0072] In order to provide the protective layer with charge transporting properties, the protective layer may be formed by curing a monomer having charge transporting properties using various polymerization or crosslinking reactions. Specifically, the protective layer is preferably formed by polymerizing or crosslinking a charge transporting compound having a chain-polymerizable functional group and curing the polymerized compound.

[0073] The protective layer may also contain conductive particles, ultraviolet absorbers, and lubricating particles such as fluorine-containing resin particles. The conductive particles are preferably metal oxide particles such as tin oxide particles. While there is no limitation on the thickness of the protective layer, it is preferably 0.05 μm or more and 20 μm or less.

[0074] Examples of methods that can be used to apply the coating liquid for each layer include dip coating (dipping), spray coating, spinner coating, bead coating, blade coating, and beam coating. Among these, dip coating is preferred from the viewpoints of efficiency and productivity.

[0075] [Process cartridges, electrophotographic devices] The process cartridge according to the present invention integrally supports the electrophotographic photosensitive member described above and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attachable to the main body of the electrophotographic apparatus.

[0076] The electrophotographic apparatus according to the present invention comprises the electrophotographic photosensitive member described above, as well as a charging means, an exposing means, a developing means, and a transferring means.

[0077] FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member.

[0078] A cylindrical (drum-shaped) electrophotographic photoreceptor 1 is rotated in the direction of the arrow around an axis 2 at a predetermined peripheral speed (process speed). The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by charging means 3 during the rotation process.

[0079] 2 shows a roller charging method using a roller-type charging member, but other charging methods such as a corona charging method, a proximity charging method, and an injection charging method may also be used. Exposure light 4 is irradiated onto the surface of the charged electrophotographic photosensitive member 1 from an exposure means (not shown), and an electrostatic latent image corresponding to the target image information is formed.

[0080] The exposure light 4 is light whose intensity is modulated in accordance with a time-series electric digital image signal of the target image information, and is output from an image exposure means such as a slit exposure or laser beam scanning exposure. The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed (normal development or reversal development) with toner contained in the developing means 5, and a toner image is formed on the surface of the electrophotographic photosensitive member 1.

[0081] The toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred to a transfer material 7 by transfer means 6. At this time, a bias voltage of a polarity opposite to the charge carried by the toner is applied to the transfer means 6 from a bias power supply (not shown). When the transfer material 7 is paper, the transfer material 7 is taken out from a paper feed unit (not shown) and fed between the electrophotographic photosensitive member 1 and transfer means 6 in synchronization with the rotation of the electrophotographic photosensitive member 1.

[0082] The transfer material 7 onto which the toner image has been transferred from the electrophotographic photosensitive member 1 is separated from the surface of the electrophotographic photosensitive member 1 and transported to fixing means 8, where the toner image is fixed, and the transferred material is printed out of the electrophotographic device as an image-formed product (print, copy). The electrophotographic device may have cleaning means 9 for removing toner and other adhering matter remaining on the surface of the electrophotographic photosensitive member 1 after transfer.

[0083] Furthermore, a so-called cleanerless system may be used in which the cleaning means 9 is not provided separately and the deposits are removed by the developing means 5 or the like.

[0084] In the present invention, the electrophotographic photosensitive member 1 and components selected from the charging means 3, developing means 5, cleaning means 9, etc. are housed in a container and integrally supported to form a process cartridge 11. This can be configured to be detachably attached to the main body of the electrophotographic apparatus.

[0085] For example, it can be configured as follows: At least one selected from charging means 3, developing means 5, and cleaning means 9 is integrally supported together with an electrophotographic photosensitive member 1 to form a cartridge. This can be made into a process cartridge 11 that is detachably attached to the main body of the electrophotographic apparatus using guide means 12 such as a rail of the main body of the electrophotographic apparatus.

[0086] The electrophotographic apparatus may have a charge-removing mechanism that removes charge from the surface of the electrophotographic photosensitive member 1 with pre-exposure light 10 from pre-exposure means (not shown). In addition, guide means 12 such as a rail may be provided to mount and remove the process cartridge 11 according to the present invention to the main body of the electrophotographic apparatus.

[0087] The electrophotographic photoreceptor according to the present invention can be used in laser beam printers, LED printers, copying machines, facsimiles, and multifunction machines thereof. [Example]

[0088] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following examples, "parts" are based on mass unless otherwise specified.

[0089] <Preparation example of carbon black> Carbon black (product name: Thermax N990, manufactured by Cancarb, pH 11.0, ash 0.05%, DBP oil absorption 38 cm 3 The carbon black particles (100 g / 100 g, number-average primary particle size: 280 nm) were classified using an elbow jet classifier (product name: EJ-PURO, manufactured by Nittetsu Mining Co., Ltd.). As a result, classified carbon black particles 1 with a number-average primary particle size of 480 nm and classified carbon black particles 2 with a number-average primary particle size of 210 μm were obtained.

[0090] <Preparation Example of Coating Solution 1 for First Intermediate Layer> The following materials were prepared: 15 parts of butyral resin (product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol resin 15 parts of blocked isocyanate resin (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) These were dissolved in a mixed solvent of 45 parts of methyl ethyl ketone and 85 parts of 1-butanol to obtain a solution. To this solution was added 10.7 parts of carbon black (trade name: Thermax N990, manufactured by Cancarb, number-average primary particle size 280 nm). The solution after the addition of carbon black was placed in a vertical sand mill using 180 parts of glass beads with an average particle size of 1.0 mm as a dispersion medium, and subjected to dispersion treatment for 4 hours under conditions of a rotation speed of 1500 rpm (circumferential speed 5.5 m / s) in an atmosphere of 23±3°C to obtain a dispersion liquid. To this dispersion, 0.01 parts of silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Dow Corning Toray Co., Ltd.) was added as a leveling agent. At the same time, 5.0 parts of cross-linked polymethyl methacrylate (PMMA) particles (trade name: Techpolymer SSX-103, manufactured by Sekisui Plastics Co., Ltd., average primary particle size 3.1 μm) were added as a surface roughness imparting agent. The mixture was then stirred to prepare Coating Solution 1 for the first intermediate layer.

[0091] <Preparation Example of Coating Solution 2 for First Intermediate Layer> Phenolic resin as a binder resin (product name: Plyofen J-325, manufactured by DIC Corporation, resin solid content 60%, density after curing 1.3 g / cm 2 168 parts of the above compound were dissolved in 98 parts of 1-methoxy-2-propanol as a solvent to obtain a solution. This solution was added to carbon black (trade name: Thermax N990, manufactured by Cancarb, pH 11.0, ash content 0.05%, DBP oil absorption 38 cm 3 38.3 parts of carbon black (100 g / 100 g, number-average primary particle size: 280 nm) was added. The solution after adding the carbon black was placed in a sand mill using 420 parts of glass beads with a diameter of 0.8 mm, and subjected to dispersion treatment at a rotation speed of 1500 rpm for 4 hours to obtain a dispersion liquid. To this dispersion, silicone resin particles (product name: Tospearl 120, manufactured by Momentive Performance Materials, Inc., average particle size 2 μm, density 1.3 g / cm) were added as a surface roughening agent. 2 To the mixture, 13.8 parts of 1-methoxy-2-propanol (product name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.) were added. At the same time, 0.014 parts of silicone oil (product name: SH28PA) as a leveling agent, 6 parts of methanol, and 6 parts of 1-methoxy-2-propanol were added. The mixture was then stirred to prepare a first intermediate layer coating solution 2.

[0092] <Preparation Examples of Coating Solutions 3 to 12 for First Intermediate Layer> First intermediate layer coating solutions 3 to 12 were prepared using the same procedures as in the preparation example of first intermediate layer coating solution 1, except that the type and amount (parts by mass) of carbon black particles used in preparing the first intermediate layer coating solution were as shown in Table 1.

[0093] [Table 1]

[0094] Table 2 shows the pH, ash content, and DBP oil absorption of the carbon black used in preparing the first intermediate layer coating liquid. [Table 2]

[0095] <Preparation Example of Coating Solution 1 for Second Intermediate Layer> The following materials were prepared: 15 parts of butyral resin (product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol resin 15 parts of blocked isocyanate resin (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) These were dissolved in a mixed solvent of 45 parts of methyl ethyl ketone and 85 parts of 1-butanol to obtain a solution. A total of 40 parts by mass of perinone compound (1-1) and perinone compound (2-1) were mixed into the resulting mixture at a mass ratio of 1:1. The solution to which the perinone compounds had been added was dispersed in a sand mill using 1 mmφ glass beads for 10 hours to obtain a dispersion. To this dispersion, 0.01 parts of silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Dow Corning Toray Co., Ltd.) was added as a leveling agent. At the same time, 5.0 parts of cross-linked polymethyl methacrylate (PMMA) particles (trade name: Techpolymer SSX-103, manufactured by Sekisui Plastics Co., Ltd., average primary particle size 3.1 μm) were added as a surface roughness imparting agent. The mixture was then stirred to prepare Coating Solution 1 for the second intermediate layer.

[0096] <Preparation Example of Coating Solution 2 for Second Intermediate Layer> A solution was obtained by dissolving 27 parts by mass of a polyamide resin (product name: CM8000, manufactured by Toray Industries, Inc.) in a mixed solvent of 120 parts by mass of methanol / 60 parts by mass of isopropanol. A total of 40 parts by mass of perinone compound (1-1) and perinone compound (2-1) were mixed into the resulting mixture at a mass ratio of 1:1. The solution to which the perinone compounds had been added was dispersed in a sand mill using 1 mmφ glass beads for 10 hours to obtain a dispersion. To this dispersion, 2 parts by mass of silicone resin particles (trade name: Tospearl 145, manufactured by Momentive Performance Materials) were added to prepare a second intermediate layer coating solution 2.

[0097] <Preparation Example of Coating Solution 3 for Second Intermediate Layer> 27 parts by mass of polycarbonate resin (trade name: Panlite TS-2050, manufactured by Teijin Ltd.) was dissolved in 160 parts by mass of tetrahydrofuran. A total of 40 parts by mass of perinone compound (1-1) and perinone compound (2-1) were mixed with the resulting solution at a mass ratio of 1:1. The solution to which the perinone compounds had been added was dispersed in a sand mill using 1 mmφ glass beads for 10 hours to obtain a dispersion. To this dispersion, 2 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials) were added to prepare a second intermediate layer coating solution 3.

[0098] <Preparation Examples of Coating Solutions 4 to 23 for Second Intermediate Layer> Second intermediate layer coating solutions 4 to 23 were prepared using the same procedures as in the preparation example of second intermediate layer coating solution 1, except that the type and amount (parts by mass) of the perinone compound used in preparing the second intermediate layer coating solution were as shown in Table 3.

[0099] [Table 3]

[0100] <Preparation Example of Coating Solution 24 for Second Intermediate Layer> A second intermediate layer coating solution 24 was prepared using the same procedure as in the preparation example of the second intermediate layer coating solution 1, except that 40 mass parts of a compound represented by the following structural formula (C1) were used instead of the perinone compound used in preparing the second intermediate layer coating solution 1. [ka]

[0101] [Examples 1a to 1d] (Support) A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as a support (conductive support). It was ultrasonically cleaned in a cleaning solution containing pure water and detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.), and after the cleaning solution was rinsed off, it was further ultrasonically cleaned in pure water for degreasing, and this was used as a support.

[0102] (First middle class) Next, the first intermediate layer coating liquid 1 was dip-coated onto the support, and the resulting coating film was dried and heat-cured at 160°C for 30 minutes to form a first intermediate layer with a film thickness of 28 µm.

[0103] (The second middle class) Next, the second intermediate layer coating solution 1 was dip-coated onto the first intermediate layer to a film thickness shown in Table 4, and the resulting coating film was dried and heat-cured at 160°C for 30 minutes to form a second intermediate layer.

[0104] [Table 4]

[0105] (charge generation layer) The following materials were prepared: Four hydroxygallium phthalocyanine crystals (charge generating materials) with strong peaks at 7.4° and 28.1°, with Bragg angles 2θ±0.2° in CuKα characteristic X-ray diffraction. 0.04 parts of a compound represented by the following formula (A): [ka] These were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. The solution obtained was placed in a sand mill using glass beads with a diameter of 1 mm, and dispersed in an atmosphere of 23±3°C for 1 hour. After the dispersion treatment, 100 parts of ethyl acetate was added to prepare a coating liquid for the charge generating layer. This charge generating layer coating liquid was dip coated onto the second intermediate layer formed above to form a coating film, and the resulting coating film was dried at 90°C for 10 minutes to form a charge generating layer with a film thickness of 0.19 μm.

[0106] (charge transport layer) Next, the following materials were prepared: 8 parts of an amine compound (hole transport material) represented by the following structural formula (7) [ka] 10 parts of a polyester resin (P1) having a weight average molecular weight (Mw) of 100,000 and containing a repeating structural unit represented by the following formula (8) and a repeating structural unit represented by the following formula (9) in a molar ratio of 5:5: [ka] [ka] These were dissolved in a mixed solvent of 40 parts of dimethoxymethane and 60 parts of chlorobenzene to prepare a coating solution for the charge transport layer. This charge transport layer coating liquid was dip coated onto the charge generating layer, and the resulting coating was dried at 120° C. for 40 minutes to form a charge transport layer having a thickness of 15 μm. According to the above procedure, electrophotographic photoreceptors according to Examples 1a to 1d were produced.

[0107] [Comparative Examples 1a to 1d] Electrophotographic photoreceptors according to Comparative Examples 1a to 1d were produced in the same manner as in Examples 1a to 1d, except that the first intermediate layer was not provided.

[0108] [Examples 2a to 22 and Comparative Examples 2a to 5] Electrophotographic photoreceptors according to Examples 2a to 22 and Comparative Examples 2a to 5 were prepared in the same manner as in Examples 1a to 1d, except that the types and film thicknesses of the coating liquids used to form the first intermediate layer and the second intermediate layer were as shown in Table 5.

[0109] [Table 5]

[0110] [Evaluation of electrophotographic photoreceptors] The electrophotographic photoreceptors prepared above were evaluated as follows.

[0111] (Evaluation of dark decay) To evaluate the dark decay, a multifunction printer imageRUNNER ADVANCE C5255 (registered trademark) manufactured by Canon Inc. was prepared as an evaluation machine. The cyan developing cartridge was removed from the prepared evaluation machine, and a potential measuring device was attached to it. The potential measuring device is a device in which a potential measuring probe is placed at the developing position of the developing cartridge. The position of the potential measuring probe was the center of the generating line direction of the electrophotographic photosensitive member. Using such an evaluation machine, a drum cartridge equipped with an electrophotographic photosensitive member to be evaluated was attached to the cyan station, and the surface potential of the electrophotographic photosensitive member was measured. The measurement was performed by first adjusting the charging conditions so that the electrophotographic photosensitive member's charging potential (dark potential) was -900 V. Then, while the device was still charged, the operation of the device was suddenly stopped, and the profile of the electrophotographic photosensitive member's potential decay after the stoppage was measured. More specifically, the surface potential (Vd0.1) 0.1 seconds after charging and the surface potential (Vd1.0) 1.0 seconds after charging were measured, and the ratio (Vdd) of Vd1.0 to Vd0.1 was defined as the dark decay. A larger Vdd value indicates a higher dark decay suppression effect. Based on the obtained Vdd, the evaluation was made according to the following evaluation criteria A to C. The evaluation of dark decay was carried out at an early stage before the start of a paper feed durability test to be performed in the evaluation of fogging described later, and after the end of the paper feed durability test under two different temperature and humidity environments. The evaluation results are shown in Table 6. A: Vdd is 0.90 or more B: Vdd is 0.85 or more and less than 0.90 C: Vdd is less than 0.85

[0112] (Fogging evaluation) The evaluation of fogging was carried out by mounting the electrophotographic photosensitive member in a multifunction printer, imageRUNNER ADVANCE C5255 (registered trademark), manufactured by Canon Inc. More specifically, a drum cartridge equipped with the electrophotographic photosensitive member to be evaluated was mounted in the cyan station of the multifunction printer, and the evaluation was carried out. The electrophotographic apparatus equipped with the electrophotographic photoreceptor to be evaluated was subjected to a paper feed durability test in an environment of 30°C / 80% RH or 32.5°C / 85% RH. The paper feed durability test was carried out using a cyan monochrome character image chart with a print rate of 1% and A4 size plain paper. An image with an all-white background was printed on A3-size plain paper and the fog density was measured at the beginning of the paper feed durability test and after the end of the 50,000-sheet paper feed durability test. The fog density was measured using a white light meter (product name: REFLECTMETER TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.). Specifically, the fog density (%) (= Dr (%) - Ds (%)) was calculated from the difference between the whiteness (reflectance Ds (%)) of the image to be evaluated and the whiteness (reflectance Dr (%)) of unused paper of the same type as the image to be evaluated. Based on the calculated fog density, the image was judged and evaluated according to the following criteria A to E. The evaluation results are shown in Table 6. A: Fog density is less than 0.2% B: Fog density is 0.2% or more and less than 0.5% C: Fog density is 0.5% or more and less than 1.0% D: Fog density is 1.0% or more and less than 2.0% E: Fog density is 2.0% or more

[0113] (Evaluation of sensitivity reduction) Using the same evaluation machine as that used in the evaluation of fogging, a drum cartridge equipped with an electrophotographic photosensitive member to be evaluated was attached to the cyan station, and the surface potential of the electrophotographic photosensitive member was measured. In the measurement, first, before the above-mentioned fogging evaluation was performed, the charging conditions were adjusted so that the dark area potential of the initial electrophotographic photosensitive member was −700 V, and the laser power was adjusted so that the light area potential was −300 V. Thereafter, the electrophotographic photoreceptor was subjected to the above-described paper feed durability test for fogging evaluation, and the potential of the electrophotographic photoreceptor was measured after the paper feed durability test. At that time, the charging conditions were adjusted so that the dark area potential was -700 V, and the light area potential was measured under the condition that the laser power was adjusted to the laser output adjusted in the initial potential measurement. The difference between the measured light area potential after the paper feed durability test and the initial light area potential (-300 V) was calculated and defined as the sensitivity change ΔV. Based on this ΔV, the evaluation was made according to the following criteria A to E. The evaluation results are shown in Table 6. A: Sensitivity reduction is less than 5V B: Sensitivity reduction is 5V or more and less than 10V C: Sensitivity reduction is 10V or more and less than 25V D: Sensitivity reduction is 25V or more and less than 40V E: Sensitivity drop is 40V or more

[0114] [Table 6]

[0115] As is clear from Table 6, the electrophotographic photoreceptor according to the present invention has improved hole blocking properties, suppresses an increase in dark decay during repeated use over a long period of time, and is excellent in the evaluation of fogging.

[0116] In particular, it can be confirmed that in Comparative Examples 1a to 1d, the dark attenuation increased as the thickness of the second intermediate layer became thinner, whereas in Examples 1a to 1d, excellent results were obtained regardless of the thickness.

[0117] Furthermore, Comparative Examples 1a to 1d, 2a, and 2b, which had a configuration in which a first intermediate layer was not provided and a second intermediate layer was provided directly on the support, showed a large decrease in sensitivity in a long-term durability test. This result suggests that a configuration in which there is a direct electrical interaction between the support and an intermediate layer containing an organic electron transport compound is likely to cause electrical degradation of the film, leading to a decrease in sensitivity. Comparative Example 3, which had a first intermediate layer, was able to suppress the decrease in sensitivity compared to Comparative Examples 1a to 1d, 2a, and 2b, but it was found that the layer configuration of the present invention can achieve even greater improvement.

[0118] Disclosure of embodiments of the present invention includes the following. (Configuration 1) An electrophotographic photoreceptor having a support, a first intermediate layer, a second intermediate layer, and a photosensitive layer in this order, the first intermediate layer contains a binder resin and carbon black, The second intermediate layer contains a binder resin and at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (1) and perinone compounds represented by the following formula (2): An electrophotographic photoreceptor characterized by the above-mentioned. [ka] [ka] (R in Equation (1) 11 ~R 18 and R in formula (2) 21 ~R 28 each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, or R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 , and R 25 ~R 28In each group, adjacent groups may be linked to form a ring. (Configuration 2) 2. The electrophotographic photoreceptor according to claim 1, wherein the content of the perinone compound in the second intermediate layer is 30% by mass or more and 70% by mass or less based on the total mass of the second intermediate layer. (Configuration 3) 3. The electrophotographic photoreceptor according to claim 1, wherein the content of the carbon black in the first intermediate layer is 0.5% by mass or more and 30% by mass or less, based on the total mass of the first intermediate layer. (Configuration 4) the content of the perinone compound in the second intermediate layer relative to the total mass of the second intermediate layer is X% by mass, When the content of the carbon black in the first intermediate layer relative to the total mass of the first intermediate layer is Y mass%, 4. The electrophotographic photoreceptor according to any one of Configurations 1 to 3, wherein X / Y is 2 or more and 12 or less. (Configuration 5) The electrophotographic photoreceptor according to any one of Configurations 1 to 4, wherein the second intermediate layer contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (3) and perinone compounds represented by the following formula (4): [ka] [ka] (R in Equation (3) 31 and R 32 , and R in formula (4) 41 and R 42 each independently represents a branched alkyl group having 3 to 10 carbon atoms. (Configuration 6) The electrophotographic photoreceptor according to any one of Configurations 1 to 5, wherein the second intermediate layer contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (5) and perinone compounds represented by the following formula (6): [ka] [ka] (R in Equation (5) 51 ~R 56 , and R in formula (6) 61 ~R 66 each independently represents a methyl group, an ethyl group, or a propyl group. (Configuration 7) A process cartridge that integrally supports the electrophotographic photosensitive member according to any one of Configurations 1 to 6 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to a main body of an electrophotographic apparatus. (Configuration 8) 7. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of Configurations 1 to 6, a charging unit, an exposure unit, a developing unit, and a transfer unit. [Explanation of symbols]

[0119] 101:Support 102: The first middle class 103: The second middle class 104: Charge generation layer 105: Charge transport layer 106:Protective layer 107: Photosensitive layer 1: Electrophotographic photoreceptor 2: Axis 3: Charging means 4: Image exposure light 5: Developing method 6: Transfer means 7: Transfer material 8: Image fixing means 9: Cleaning means 10: Pre-exposure light 11: Process cartridge 12: Guidance means

Claims

1. An electrophotographic photoreceptor having a support, a first intermediate layer, a second intermediate layer, and a photosensitive layer in this order, the first intermediate layer contains a binder resin and carbon black, the second intermediate layer contains a binder resin and at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (1) and perinone compounds represented by the following formula (2): An electrophotographic photoreceptor characterized by: 【Chemistry 1】 【Chemistry 2】 (R in formula (1) １１ ~R １８ and R in formula (2) ２１ ~R ２８ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, or R １１ ~R １４ , R １５ ~R １８ , R ２１ ~R ２４ , and R ２５ ~R ２８ In each group, adjacent groups may be linked to form a ring.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the content of the perinone compound in the second intermediate layer is 30% by mass or more and 70% by mass or less with respect to the total mass of the second intermediate layer.

3. 2. The electrophotographic photoreceptor according to claim 1, wherein the content of the carbon black in the first intermediate layer is 0.5% by mass or more and 30% by mass or less with respect to the total mass of the first intermediate layer.

4. 2. The electrophotographic photoreceptor according to claim 1, wherein a content ratio of the perinone compound in the second intermediate layer relative to the total mass of the second intermediate layer is X% by mass, and a content ratio of the carbon black in the first intermediate layer relative to the total mass of the first intermediate layer is Y% by mass, and X / Y is 2 or more and 12 or less.

5. 2. The electrophotographic photoreceptor according to claim 1, wherein the second intermediate layer contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (3) and perinone compounds represented by the following formula (4): 【Transformation 3】 【Chemistry 4】 (R in formula (3) ３１ and R ３２ , and R in formula (4) ４１ and R ４２ each independently represents a branched alkyl group having 3 to 10 carbon atoms.

6. 2. The electrophotographic photoreceptor according to claim 1, wherein the second intermediate layer contains, as the perinone compound, at least one perinone compound selected from the group consisting of perinone compounds represented by the following formula (5) and perinone compounds represented by the following formula (6): 【Transformation 5】 【Transformation 6】 (R in formula (5) ５１ ~R ５６ , and R in formula (6) ６１ ~R ６６ each independently represents a methyl group, an ethyl group, or a propyl group.

7. 7. A process cartridge which integrally supports the electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to a main body of an electrophotographic apparatus.

8. 7. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit.

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