Electrophotographic photoreceptor, process cartridge, electrophotographic device, and method of manufacturing electrophotographic photoreceptor

Abstract

To provide an electrophotographic photoreceptor that offers superior cleanability and is less susceptible to image blur even when used in high-temperature, high-humidity environments.SOLUTION: An electrophotographic photoreceptor is provided, comprising a surface layer containing a binder resin, polydimethylsiloxane having a polyester chain, and oleic acid amide.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, in the field of electrophotographic devices such as copiers and printers, there has been a demand for high-speed printing in order to increase the productivity of the electrophotographic devices. As the speed of the electrophotographic devices increases, the rubbing speed between the cleaning member and the electrophotographic photosensitive member also increases. Therefore, the cleaning member may vibrate or the surface of the electrophotographic photosensitive member may be scratched, causing the untransferred toner on the electrophotographic photosensitive member to slip through the cleaning member, resulting in so-called defective cleaning.

[0003] To address the above-mentioned issues, measures have been taken, such as imparting cleaning properties to the electrophotographic photosensitive member by modifying the surface layer of the electrophotographic photosensitive member. For example, Patent Document 1 discloses a technology in which a resin having a polydimethylsiloxane structure is contained in the surface layer of the electrophotographic photosensitive member, thereby maintaining high cleaning properties for a long period of time without causing filming or image defects. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-123379 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as electrophotographic devices have become more widely used in recent years, they are increasingly being used in a variety of environments. According to the study by the present inventors, the technology described in Patent Document 1 has the problem that, although it can ensure cleaning performance due to durability, image blur occurs when used in a high-temperature, high-humidity environment.

[0006] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor that maintains high cleaning properties and does not cause image blurring even under high temperature and high humidity conditions, and to provide a method for producing the electrophotographic photoreceptor. [Means for solving the problem]

[0007] The above object can be achieved by the present invention as follows. That is, the present invention provides: An electrophotographic photoreceptor having a surface layer containing a binder resin, The electrophotographic photoreceptor is characterized in that the surface layer contains polydimethylsiloxane having a polyester chain and oleic acid amide. The present invention also provides a process cartridge that 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 an electrophotographic apparatus. The present invention also provides an electrophotographic apparatus comprising the above electrophotographic photosensitive member, a charging means, an exposure means, a developing means and a transfer means. The present invention also provides A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising: a preparation step of preparing a coating liquid for the surface layer; a coating step of coating the coating liquid; a solidification step of solidifying the applied coating liquid by drying or curing, The method for producing an electrophotographic photoreceptor is characterized in that the coating liquid contains polydimethylsiloxane having a polyester chain and oleic acid amide. [Effects of the Invention]

[0008] According to the present invention, the electrophotographic photoreceptor can maintain high cleaning performance even in a high-speed electrophotographic apparatus, and can also suppress the occurrence of image blurring even in a high-temperature, high-humidity environment. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1(a) shows one example of the layer structure of the electrophotographic photosensitive member according to the present invention, and FIG. 1(b) shows another example of the layer structure of the electrophotographic photosensitive member according to the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with the electrophotographic photosensitive member of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of a schematic configuration of a process cartridge equipped with the electrophotographic photosensitive member of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment The first embodiment relates to an electrophotographic photoreceptor. The electrophotographic photoreceptor of the present invention comprises An electrophotographic photoreceptor having a surface layer containing a binder resin, The surface layer is characterized by containing polydimethylsiloxane having polyester chains and oleic acid amide. Preferred embodiments of the present invention will now be described.

[0011] [Electrophotographic photoreceptor] The electrophotographic photoreceptor of the present invention is characterized by having a surface layer containing a binder resin. Here, the surface layer refers to the layer located on the outermost surface of the electrophotographic photosensitive member, and refers to the layer that comes into contact with the charging member, toner, or cleaning member.

[0012] 1(a) and 1(b) are diagrams showing an example of the layer structure of an electrophotographic photoreceptor. The electrophotographic photoreceptor in Fig. 1(a) has a support 11, an undercoat layer 12, a charge generation layer 13, a charge transport layer 14, and a protective layer 15. The electrophotographic photoreceptor in Fig. 1(b) has a support 11, an undercoat layer 12, a charge generation layer 13, and a charge transport layer 14.

[0013] The electrophotographic photoreceptor of the present invention may also be in the form of a belt or sheet. The electrophotographic photosensitive member of the present invention is used in an image forming method having a charging step of charging the surface of the electrophotographic photosensitive member, an exposure step of exposing the charged electrophotographic photosensitive member to light to form an electrostatic latent image, a development step of supplying toner to the electrophotographic photosensitive member on which the electrostatic latent image has been formed to form a toner image, and a transfer step of transferring the toner image formed on the electrophotographic photosensitive member. The support and each layer will be described below.

[0014] <Surface layer> The surface layer here refers to a portion of the electrophotographic photosensitive member that comes into contact with toner and various members during the electrophotographic process. The surface layer can be a protective layer, a charge transport layer, or a single-layer photosensitive layer, but from the viewpoint of achieving both durability in repeated use and basic electrical properties in the electrophotographic process, the surface layer is preferably a protective layer.

[0015] The inventors have conducted research and found that in order to suppress image blur while ensuring high cleaning performance, the surface layer must contain a binder resin, polydimethylsiloxane having a polyester chain (sometimes referred to as polyester-modified polydimethylsiloxane), and oleic acid amide.

[0016] Furthermore, in a method for producing an electrophotographic photoreceptor that can suppress image blur while ensuring high cleanability, it is necessary for the coating liquid for the surface layer to contain polydimethylsiloxane having a polyester chain and oleic acid amide.

[0017] Although the reason why the above conditions enable the present invention to exhibit its effects is not clearly understood, the present inventors speculate as follows. The suppression of image blur explained above is believed to be as follows.

[0018] In the charging process, discharge occurs between the electrophotographic photosensitive member and the charging member, generating oxidizing gases such as ozone and nitrogen oxides, which deteriorate the materials used in the surface layer of the electrophotographic photosensitive member and generate discharge products. These discharge products absorb moisture in the air, which can cause the electrostatic latent image formed on the electrophotographic photosensitive member to collapse, resulting in so-called image blurring. In this case, if the surface layer of the electrophotographic photoreceptor absorbs moisture, the resistance decreases, causing more noticeable image blur. If polyester-modified polydimethylsiloxane is contained in the coating liquid for the surface layer of the electrophotographic photoreceptor, the polydimethylsiloxane component acts as a surfactant during coating of the surface layer, and the polyester-modified polydimethylsiloxane is likely to migrate to the outermost surface. Therefore, while cleaning properties are ensured, the ester bond sites in polyester-modified polydimethylsiloxane tend to adsorb HO molecules, which is thought to accelerate the reduction in resistance of the outermost surface layer and promote the occurrence of image blur.

[0019] On the other hand, oleic acid amide also has a long-chain hydrocarbon group, which makes it easy to migrate to the surface, and since it has an amide group at the end, it is easy to adsorb to the ester bond of polyester-modified polydimethylsiloxane. Furthermore, oleic acid amide has a long hydrocarbon chain length that is poorly compatible with H2O molecules, and has a double bond in the center of the hydrocarbon chain, making the long hydrocarbon chain of oleic acid amide less likely to become entangled. Therefore, oleic acid amide can maintain a large steric hindrance while adsorbing to the ester bond sites where HO molecules are easily adsorbed. Therefore, when the surface layer contains polyester-modified polydimethylsiloxane and oleic acid amide, which ensure cleaning properties, HO molecules are prevented from adsorbing to the ester bond sites of the polyester-modified polydimethylsiloxane. As a result, it is believed that even in a high-temperature, high-humidity environment, the surface layer is prevented from decreasing in resistance, making it possible to achieve both less image blurring and high cleaning performance.

[0020] In the electrophotographic photoreceptor of the present invention, the surface layer preferably contains metal oxide particles. When the surface layer contains metal oxide particles, the effects of the present invention become more pronounced. This is because metal oxides have a very low volume resistivity compared to resins and organic materials that perform charge transport functions, and the volume resistivity of the entire surface layer decreases. Therefore, it is presumed that the influence of the decrease in resistance of the resin portion due to moisture adsorption becomes greater, and image blurring is more likely to occur. In the electrophotographic photoreceptor of the present invention, the metal oxide particles preferably contain tin atoms, and are more preferably ITO particles.

[0021] Furthermore, when using metal oxide particles to ensure the charge transport performance of the surface layer, the loading amount must be adjusted depending on the powder resistivity of the metal oxide particles. Metal oxide particles with low powder resistivity can be loaded at a low loading amount, but metal oxide particles with high powder resistivity require a high volume loading amount. Since electrophotographic photoreceptors form an electric latent image by irradiating a photosensitive layer with a laser, if the loading amount of metal oxide particles in the surface layer is high, the light transmittance of the surface layer decreases, leading to a decrease in the sensitivity of the electrophotographic photoreceptor. Therefore, it is preferable that the powder has a low resistivity so that the charge transport performance can be exhibited with a low filling amount. 2 Ω·cm or less is preferable, and 10 1 Ω·cm or less.

[0022] The surface layer of the electrophotographic photoreceptor of the present invention is characterized by containing a polyester-chain-containing polydimethylsiloxane and oleic acid amide. The content of the polyester-modified polydimethylsiloxane in the surface layer, excluding the metal oxide particles in the surface layer, is preferably 0.1% by mass or more and 1.0% by mass or less. If the amount is less than 0.1% by mass, it is difficult to ensure sufficient cleaning properties, and if the amount exceeds 1.0% by mass, image defects are likely to occur at the contact portion with the electrophotographic photosensitive member, particularly at the contact portion with the charging roller, in a high-temperature, high-humidity environment. In the present invention, common chemical substances such as oleic acid amide can be confirmed by, for example, nuclear magnetic resonance (NMR) and gas chromatography mass spectrometry (GC-MS).

[0023] In the present invention, the polydimethylsiloxane having a polyester chain is preferably a polyester-modified polydimethylsiloxane, and more preferably a compound represented by the following formula (B). [ka] (In the formula (B), R 1 is an aliphatic hydrocarbon group having 1 to 15 carbon atoms, and R 2 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R 3 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R 4 represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group having from 1 to 15 carbon atoms, x represents an integer of 1 to 300, y represents an integer of 1 to 100, j represents an integer of 1 to 15, k represents an integer of 0 to 5, and m represents an integer of 1 to 20. In the present invention, the compound represented by the formula (B) can be confirmed by NMR, GC-MS, and matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS).

[0024] In the surface layer of the electrophotographic photoreceptor of the present invention, the content of oleic acid amide is preferably 40 parts by mass or more and 160 parts by mass or less per 100 parts by mass of polyester-modified polydimethylsiloxane. If the content is less than 40 parts by mass, adsorption of HO molecules to the ester bond sites of the polyester-modified polydimethylsiloxane cannot be sufficiently suppressed, and image blurring is less suppressed. If the content exceeds 160 parts by mass, image defects are likely to occur at the contact part with the electrophotographic photoreceptor, particularly at the contact part with the charging roller, in a high-temperature, high-humidity environment.

[0025] The binder resin of the surface layer is preferably a polymerized and cured film of an acrylic resin, an epoxy resin, a phenolic resin, a melamine resin, or the like, and more preferably a polymerized and cured film of a composition containing a (meth)acrylic compound. The polymerized and cured film has high film strength, can prevent the surface layer from being scraped off, and can suppress the film resistance from decreasing when moisture is adsorbed due to reduced molecular mobility. As the (meth)acrylic compound, a polymerized and cured film of a tetra- to hexa-functional (meth)acrylic monomer is more preferred, and a hexa-functional urethane (meth)acrylic monomer is even more preferred. Furthermore, the polyester-modified polydimethylsiloxane preferably has a (meth)acrylic group. When the binder resin of the surface layer is a polymerized and cured film of a composition containing a (meth)acrylic compound, if the polyester-modified polydimethylsiloxane has a (meth)acrylic group, it reacts with and is fixed to the polymerized and cured film, thereby maintaining high cleaning performance for a long period of time.

[0026] In addition, the electrophotographic photoreceptor of the present invention has a surface layer having a Martens hardness of 150 N / mm 2 More than 300N / mm 2 It is preferable that the strength is 150N / mm or less. 2 If it is less than 300N / mm, the abrasion resistance will be poor. 2 If the hardness exceeds this, the surface layer becomes brittle and cracks or chips may occur. The Martens hardness of the surface layer can be measured using the method specified in ISO14577.

[0027] <Support> In the present invention, the electrophotographic photoreceptor has a support. In the present invention, the support is preferably a conductive support having electrical conductivity. The shape of the support may be cylindrical, belt-like, sheet-like, or the like. Of these, a cylindrical support is preferred. The surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like.

[0028] The support is preferably made of a metal, a resin, or a glass. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof, among which an aluminum support using aluminum is preferred. Furthermore, the resin or glass may be made conductive by mixing or coating it with a conductive material.

[0029] <Conductive layer> In the electrophotographic photoreceptor used in the present invention, a conductive layer may be provided on the support, which can conceal scratches and irregularities on the support surface and control light reflection on the support surface.

[0030] The conductive layer preferably contains conductive particles and a resin. Examples of materials for the conductive particles include metal oxides, metals, and carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc.

[0031] Among these, it is preferable to use metal oxides as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide. When metal oxides are used as conductive particles, the surfaces of the metal oxides may be treated with a silane coupling agent or the like, or the metal oxides may be doped with elements such as phosphorus or aluminum or their oxides, such as phosphorus, aluminum, niobium, and tantalum.

[0032] The conductive particles may have a laminated structure including a core particle and a coating layer covering the core particle. Examples of the core particle include titanium oxide, barium sulfate, and zinc oxide. Examples of the coating layer include metal oxides such as tin oxide and titanium oxide. When metal oxide particles are used as the conductive particles, the volume average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0033] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like. The thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0034] The conductive layer can be formed by preparing a coating solution for the conductive layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying the coating film. 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. Examples of a method for dispersing the conductive particles in the coating liquid for the conductive layer include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0035] <Undercoat layer> In the electrophotographic photoreceptor used in the present invention, an undercoat layer may be provided on the support or the conductive layer. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

[0036] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin.

[0037] Examples of the polymerizable functional group contained in 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 hydroxy group, an amino group, a carboxy group, a thiol group, a carboxylic acid anhydride group, and a carbon-carbon double bond group. Furthermore, for the purpose of improving electrical properties, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, a conductive polymer, etc. Among these, it is preferable to use an electron transporting substance or a metal oxide.

[0038] Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the above-mentioned monomer having the polymerizable functional group.

[0039] Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, silicon dioxide, etc. Examples of metals include gold, silver, aluminum, etc. The undercoat layer may further contain additives.

[0040] The thickness of the undercoat layer is preferably from 0.1 μm to 50 μm, more preferably from 0.2 μm to 40 μm, and particularly preferably from 0.3 μm to 30 μm.

[0041] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0042] <Photosensitive layer> The photosensitive layer of the electrophotographic photoreceptor according to the present invention is mainly classified into (1) a multi-layer type photosensitive layer and (2) a single-layer type photosensitive layer. (1) The multi-layer type photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. (2) The single-layer type photosensitive layer has a photosensitive layer containing both a charge generation material and a charge transport material.

[0043] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generating layer and a charge transport layer. (1-1) Charge Generating Layer The charge generating layer preferably contains a charge generating material and a resin. Examples of charge-generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.

[0044] 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.

[0045] Examples of the resin 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, polyvinyl chloride resin, etc. Among these, polyvinyl butyral resin is more preferred.

[0046] The charge generating layer may further contain additives such as antioxidants and ultraviolet absorbers, etc. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0047] The thickness of the charge generating layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0048] 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 a coating film from the coating solution, and drying the coating film. 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.

[0049] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a resin. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred.

[0050] The structures of CTM1 to CTM10 are shown below as examples of preferred charge transport materials. [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0051] The content of the charge transport material in the charge transport layer is preferably 25% by mass to 70% by mass, and more preferably 30% by mass to 55% by mass, based on the total mass of the charge transport layer.

[0052] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among these, polycarbonate resin, polyester resin, and acrylic resin are preferred. As the polyester resin, polyarylate resin is particularly preferred.

[0053] The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0054] The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0055] The thickness of the charge transport layer is preferably from 5 μm to 50 μm, more preferably from 8 μm to 40 μm, and particularly preferably from 10 μm to 30 μm.

[0056] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred. When the charge transport layer is used as the surface layer, it contains polyester-modified polydimethylsiloxane and oleic acid amide as described above in the section <Surface Layer>.

[0057] (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 a support, a conductive layer, or an undercoat 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.

[0058] <Protective layer> In the electrophotographic photoreceptor according to the present invention, a protective layer may be provided on the photosensitive layer, which can improve durability. The protective layer is provided for the purpose of providing durability for a long life, and may be, for example, a high-strength layer containing a resin, and does not necessarily need to contain conductive particles or a charge transport material to improve charge transport performance. However, from the viewpoint of improving the basic electrical properties of the electrophotographic photoreceptor, it is preferable to contain conductive particles and / or a charge transport material and a resin to achieve both durability and basic electrical properties.

[0059] The metal oxide particles preferably have a low volume resistivity and are effective as a charge control agent for toner. From this viewpoint, the metal oxide particles preferably include at least one metal oxide particle selected from the group consisting of indium tin oxide particles, tin oxide particles, titanium oxide particles, zinc oxide particles, and aluminum oxide particles. Indium tin oxide is particularly preferred.

[0060] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred.

[0061] From the viewpoint of cost, it is preferable that the protective layer does not contain an organic compound having a charge transport function. In this case, it is preferable that the protective layer contains the above-mentioned metal oxide particles, which provide a certain degree of charge transport function, but even so, when the protective layer does not contain an organic compound having a charge transport function, the film thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less. On the other hand, if the protective layer is thinner than 0.5 μm, there is a high possibility that there will be areas that are not covered by the protective layer, and the protective layer may not function as intended. On the other hand, if the protective layer is thicker than 10 μm, when the electrophotographic photoreceptor is charged during the electrophotographic process, the protective layer will bear a large share of the voltage due to the absence of an organic compound with charge transport function. As a result, the residual potential may become extremely large, which may deteriorate the basic electrical properties. When the protective layer contains a charge transport material, the thickness of the protective layer is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 14 μm or less.

[0062] Examples of resins for the protective layer include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenolic resins, melamine resins, and epoxy resins. Among these, polycarbonate resins, polyester resins, and acrylic resins are preferred. In addition, in the electrophotographic photoreceptor of the present invention, it is preferred that polydimethylsiloxane having a polyester chain is part of the polymer film in the protective layer.

[0063] Furthermore, it is more preferable that the protective layer be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the reaction include thermal polymerization, photopolymerization, and radiation polymerization. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an acryloyl group and a methacryloyl group. A material having charge transport capability may be used as the monomer having a polymerizable functional group.

[0064] The monomer having a polymerizable functional group is preferably a (meth)acrylic compound. Examples of the reaction include thermal polymerization, photopolymerization, and radiation-induced polymerization. The protective layer of the electrophotographic photoreceptor of the present invention is preferably a polymerized film of a composition containing at least one (meth)acrylic compound selected from the group consisting of (meth)acrylic monomers and (meth)acrylic oligomers. It is more preferable that the polymer film is a composition containing at least one (meth)acrylic compound selected from the group consisting of (meth)acrylic monomers. Furthermore, in the electrophotographic photoreceptor of the present invention, the composition containing the (meth)acrylic compound preferably contains a hexafunctional urethane acrylic monomer and / or a hexafunctional urethane acrylic oligomer. By doing so, the electrophotographic photoreceptor of the present invention can maintain high cleaning performance even in a high-speed electrophotographic apparatus, and can also suppress the occurrence of image blurring even in a high-temperature, high-humidity environment.

[0065] As examples of preferred (meth)acrylic monomers, structures represented by the following formulae (ACM1) to (ACM56) are shown below. [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

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[0066] The protective layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slippage imparting agents, abrasion resistance improvers, etc. Specific examples of the additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0067] The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0068] <Second embodiment> The second embodiment relates to a method for manufacturing an electrophotographic photosensitive member. The method for producing an electrophotographic photoreceptor of the present invention comprises the steps of: A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising: a preparation step of preparing a coating liquid for the surface layer; a coating step of coating the coating liquid; a solidification step of solidifying the applied coating liquid by drying or curing, The coating liquid is characterized by containing polydimethylsiloxane having a polyester chain and oleic acid amide. Each step in the preparation of the surface layer will be briefly described below. The method for producing the electrophotographic photoreceptor and each substance (e.g., coating liquid) other than the surface layer can be the same as described above or a known method, and therefore the description thereof will be omitted.

[0069] (Preparation process) The electrophotographic photoreceptor of the present invention includes a preparation step of preparing a coating liquid for a surface layer. The method for preparing the coating liquid for the surface layer of the present invention may be any method that enables uniform mixing of the coating liquid, and examples thereof include a ball mill, a bead mill, stirring, ultrasonic waves, heating, and rotary stirring (roll stand), and a combination of these possible methods may also be used.

[0070] (coating process) The electrophotographic photoreceptor of the present invention includes a coating step of applying a coating liquid. Examples of methods for applying the coating liquid of the present invention include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, dip coating is preferred from the viewpoints of efficiency and productivity.

[0071] (solidification process) The electrophotographic photoreceptor of the present invention includes a solidification step in which the applied coating liquid is solidified by drying or curing. In addition, as a method for fixing the surface layer of the present invention, for example, a drying step, a curing step, or a combination thereof can be used.

[0072] (drying process) Methods for drying the applied coating solution of the present invention include, for example, heat drying, air drying, and vacuum drying, and a combination of these possible methods can also be used. In particular, heat drying and heated air drying are preferred from the viewpoint of productivity. Furthermore, in order to quickly dry the surface of the cylindrical support, it is preferred that the temperature inside the drying oven, dryer, or drying chamber be set to a desired temperature before the drying step. The drying temperature in the drying step is preferably 100° C. or more and 150° C. or less. The drying step time is preferably 20 minutes or more and 120 minutes or less, and more preferably 40 minutes or more and 100 minutes or less.

[0073] (hardening process) The method for curing the applied coating liquid of the present invention includes, for example, UV curing, heat curing, and EB curing, and a combination of these possible methods can also be used. In particular, EB curing is preferred from the viewpoint of the abrasion resistance of the electrophotographic photoreceptor.

[0074] <Application example> The application examples of the present invention are a process cartridge and an electrophotographic apparatus. The process cartridge of the present invention integrally supports the above-mentioned 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. The electrophotographic apparatus of the present invention comprises the above-mentioned electrophotographic photosensitive member, as well as a charging means, an exposing means, a developing means and a transferring means.

[0075] [Process cartridges, electrophotographic devices] FIG. 2 shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with the electrophotographic photosensitive member of the present invention. The electrophotographic apparatus of this embodiment is a so-called tandem type electrophotographic apparatus having a plurality of image forming units a to d. The first image forming unit a forms an image using toner of each color: yellow (Y), the second image forming unit b forms an image using toner of magenta (M), the third image forming unit c forms an image using toner of cyan (C), and the fourth image forming unit d forms an image using toner of each color: black (Bk). These four image forming units are arranged in a row at regular intervals, and each image forming unit has many common parts in its configuration except for the color of the toner it contains. Therefore, the electrophotographic apparatus of this embodiment will be described below using the first image forming unit a.

[0076] The first image forming section a has a photosensitive drum 1a which is a drum-shaped electrophotographic photosensitive member, a charging roller 2a which is a charging member, a developing unit 4a, and a drum cleaning unit 5a. The photosensitive drum 1a is an image carrier that carries a toner image and is driven to rotate in the direction of arrow R1 at a predetermined peripheral speed (process speed). The developing means 4a contains yellow toner and develops the yellow toner on the photosensitive drum 1a. The drum cleaning means 5a is a means for collecting toner adhering to the photosensitive drum 1a, and includes a cleaning blade that comes into contact with the photosensitive drum 1a, and a waste toner box that stores the toner and other waste matter removed from the photosensitive drum 1a by the cleaning blade.

[0077] When a control means (not shown) such as a controller receives an image signal, the image forming operation is started and the photosensitive drum 1a is rotated. During the rotation process, the photosensitive drum 1a is uniformly charged to a predetermined voltage (charging voltage) with a predetermined polarity (negative polarity in this embodiment) by the charging roller 2a, and is exposed by the exposure means 3a in accordance with the image signal. As a result, an electrostatic latent image corresponding to the yellow component of the target color image is formed on the photosensitive drum 1a, which is then developed by the developing means 4a at the development position and visualized as a yellow toner image on the photosensitive drum 1a. Here, the normal charging polarity of the toner contained in the developing means 4a is negative, and the electrostatic latent image is reversely developed with toner charged to the same polarity as the charging polarity of the photosensitive drum 1a by the charging roller 2a. However, the present invention is not limited to this, and can also be applied to an electrophotographic device in which an electrostatic latent image is positively developed with toner charged to the opposite polarity to the charging polarity of the photosensitive drum 1a.

[0078] The endless, movable intermediate transfer belt 10 is conductive, contacts the photosensitive drum 1a to form a primary transfer portion N1a, and rotates at approximately the same peripheral speed as the photosensitive drum 1a. The intermediate transfer belt 10 is stretched by an opposing roller 13 as an opposing member, and a driving roller 11, a tension roller 12, and a metal roller 14a as tension members, and is stretched by the tension roller 12 with a total tension of 60N. The intermediate transfer belt 10 can be moved by rotating the drive roller 11 in the direction of the arrow R2 in the drawing. In addition, each of the metal rollers 14a, 14b, 14c, and 14d and the opposing roller 13 is connected to ground via a Zener diode 15 serving as a constant voltage element.

[0079] The yellow toner image formed on the photosensitive drum 1a is primarily transferred from the photosensitive drum 1a to the intermediate transfer belt 10 as it passes through the primary transfer section N1a. Any residual toner remaining on the surface of the photosensitive drum 1a after the primary transfer is cleaned and removed by the drum cleaning means 5a, and then the image is used for the image formation process that follows charging.

[0080] During the primary transfer, a current is supplied to the conductive intermediate transfer belt 10 from a secondary transfer roller 20, which serves as a secondary transfer member that contacts the outer circumferential surface of the intermediate transfer belt 10. The current supplied from the secondary transfer roller 20 flows in the circumferential direction of the intermediate transfer belt 10, thereby performing the primary transfer of the toner image from the photosensitive drum 1a to the intermediate transfer belt 10. At this time, a voltage J of a predetermined polarity (positive polarity in this embodiment) opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 20 from a transfer power source 21. In the second, third and fourth image forming units in FIG. 2, the photosensitive drums are 1b, 1c and 1d, the charging rollers are 2b, 2c and 2d, the exposure means are 3b, 3c and 3d, the developing means are 4b, 4c and 4d, the drum cleaning means are 5b, 5c and 5d, the metal rollers are 14b, 14c and 14d, and the primary transfer units are N1b, N1c and N1d, respectively.

[0081] Similarly, a magenta toner image as a second color, a cyan toner image as a third color, and a black toner image as a fourth color are formed and transferred in succession onto the intermediate transfer belt 10. As a result, four color toner images corresponding to the desired color image are formed on the intermediate transfer belt 10. Thereafter, the four-color toner images carried on the intermediate transfer belt 10 are secondarily transferred all at once onto the surface of a transfer material P, such as paper or an OHP sheet, fed by a paper feeding means 50, as they pass through a secondary transfer section N2 formed by contact between the secondary transfer roller 20 and the intermediate transfer belt 10. The transfer material P onto which the four color toner images have been transferred by the secondary transfer is then heated and pressurized in the fixing means 30, whereby the four color toners are melted, mixed, and fixed onto the transfer material P. Any toner remaining on the intermediate transfer belt 10 after the secondary transfer is cleaned and removed by the belt cleaning means 16 provided opposite the opposing roller 13 via the intermediate transfer belt 10. In addition, a path is provided that does not pass through the secondary transfer roller 20, but electrically connects the transfer power supply 21 and each metal roller 14 via a constant current diode 22 as a constant current element. When a voltage is applied from the transfer power supply 21 to the secondary transfer roller 20, a pinch-off current Id flows through the constant current diode 22, separate from the current It2 that flows toward the secondary transfer portion N2. The electrophotographic photoreceptor of the present invention can be used in laser beam printers, LED printers, copiers, and the like. [Example]

[0082] 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.

[0083] The thickness of each layer of the electrophotographic photoreceptors manufactured in Examples and Comparative Examples, except for the charge generation layer, was determined by a method using an eddy current film thickness meter (Fischerscope (registered trademark), manufactured by Fisher Instruments) or by a method converting the mass per unit area into specific gravity. The film thickness of the charge generation layer was determined as follows. That is, a spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite) was pressed against the surface of the electrophotographic photosensitive member to measure the Macbeth density value. The film thickness was calculated from the measured Macbeth density value using a calibration curve previously obtained from the Macbeth density value and the film thickness measured by cross-sectional SEM image observation.

[0084] <Preparation of Coating Solution for Charge Generating Layer> [Synthesis example] 5.0 g of o-phthalodinitrile and 2.0 g of titanium tetrachloride were heated and stirred in 100 g of α-chloronaphthalene at 200°C for 3 hours, then cooled to 50°C, and the precipitated crystals were filtered off to obtain a paste of dichlorotitanium phthalocyanine. Next, this was washed with stirring in 100 mL of N,N-dimethylformamide heated to 100°C, and then washed twice with 100 mL of methanol at 60°C, followed by filtration. The resulting paste was further stirred in 100 mL of deionized water at 80°C for 1 hour and filtered to obtain 4.3 g of a blue titanyl phthalocyanine pigment.

[0085] [Milling example] 0.5 parts of the titanyl phthalocyanine pigment obtained in Synthesis Example, 10 parts of tetrahydrofuran, and 15 parts of glass beads with a diameter of 0.9 mm were milled using a sand mill for 48 hours at a cooling water temperature of 18° C. The sand mill used here was a sand mill (K-800, manufactured by Igarashi Machinery Manufacturing (now Imex), disk diameter 70 mm, number of disks 5). This was done under the condition of 500 rotations per minute of the disk. The liquid thus treated was filtered through a filter (product number: N-NO. 125T, pore size: 133 μm, manufactured by NBC Meshtec) to remove the glass beads. 30 parts of tetrahydrofuran was added to this liquid, which was then filtered. The residue on the filter was thoroughly washed with methanol and water. The washed residue was then dried under vacuum to obtain 0.45 parts of titanyl phthalocyanine pigment, which had a strong peak at a Bragg angle 2θ of 27.2°±0.3° in its X-ray diffraction spectrum using CuKα radiation.

[0086] The following materials were prepared: 12 parts of the titanyl phthalocyanine pigment obtained from the milling example 10 parts polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 158 parts cyclohexanone 402 pieces of 0.9mm diameter glass beads These were dispersed using a sand mill (K-800, manufactured by Igarashi Machinery Manufacturing (now Imex), disk diameter 70 mm, number of disks 5) at a cooling water temperature of 18°C ​​for 4 hours. The disks were rotated at 1,800 revolutions per minute. After removing the glass beads, 369 parts of cyclohexanone and 527 parts of ethyl acetate were added to the dispersion to prepare a coating solution for the charge generating layer.

[0087] <Preparation of Coating Solution for Charge Transport Layer> [Preparation of Coating Solution 1 for Charge Transport Layer] The following materials were prepared: Charge transport material CTM9: 100 parts Polycarbonate A resin having a structural unit represented by the following formula (A): 183 parts [ka] Polycarbonate Z resin having a structural unit represented by the following formula (Z): 183 parts [ka] Siloxane resin (trade name: DC200, manufactured by Toray Dow Corning Co., Ltd.): 0.03 parts These were dissolved in a mixed solvent of 1400 parts of tetrahydrofuran and 600 parts of 1,4-dioxane to prepare a coating solution 1 for the charge transport layer.

[0088] [Preparation of Coating Solution 2 for Charge Transport Layer] Charge transport layer coating liquid 2 was prepared in the same manner as charge transport layer coating liquid 1, except that 0.75 parts of BYK-310 (manufactured by BYK-CHEMIE) was added as polyester-modified polydimethylsiloxane to charge transport layer coating liquid 1.

[0089] [Preparation of Coating Solution 3 for Charge Transport Layer] Charge transport layer coating liquid 3 was prepared in the same manner as charge transport layer coating liquid 2, except that 0.75 parts of oleic acid amide (product code: O0107, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to charge transport layer coating liquid 2.

[0090] [Preparation of Coating Solution 4 for Charge Transport Layer] The following materials were prepared: Charge transport material CTM9: 100 parts Polycarbonate Z resin having a structural unit represented by the following formula (Z): 366 parts [ka] Siloxane resin (trade name: DC200, manufactured by Toray Dow Corning Co., Ltd.): 0.03 parts Polyester-modified polydimethylsiloxane: BYK-310 (manufactured by BYK-CHEMIE): 0.75 parts Oleic acid amide (product code: O0107, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.75 parts These were dissolved in a mixed solvent of 1,400 parts of tetrahydrofuran and 600 parts of 1,4-dioxane to prepare a coating solution 4 for the charge transport layer.

[0091] <Preparation of Coating Solution for Protective Layer> [Preparation of ITO dispersion 1] 29.7 parts ITO particles (product name: E-ITO, manufactured by Mitsubishi Materials Corporation) Oleic acid amide (Tokyo Chemical Industry Co., Ltd.) 0.20 parts Methyl stearate (Tokyo Chemical Industry Co., Ltd.) 0.04 parts 0.03 parts methyl palmitate (Tokyo Chemical Industry Co., Ltd.) Dimethyl glutaconate (Fujifilm Wako Pure Chemical Industries, Ltd.) 0.03 parts These were dispersed in 70 parts of 2-propanol to prepare ITO dispersion liquid 1.

[0092] [Preparation of ITO dispersion 2] ITO Dispersion 2 was prepared in the same manner as ITO Dispersion 1, except that the amount of oleic acid amide in the ITO dispersion was 0.13 parts and the amount of methyl stearate was 0.11 parts.

[0093] [Preparation of ITO dispersion 3] ITO Dispersion 3 was prepared in the same manner as ITO Dispersion 1, except that the amount of oleic acid amide added to the ITO dispersion was 0.10 parts and the amount of methyl stearate added was 0.14 parts.

[0094] [Preparation of ITO dispersion 4] ITO Dispersion 4 was prepared in the same manner as ITO Dispersion 1, except that the amount of oleic acid amide added to the ITO dispersion was 0.09 parts and the amount of methyl stearate added was 0.15 parts.

[0095] [Preparation of ITO dispersion 5] 29.7 parts ITO particles (product name: E-ITO, manufactured by Mitsubishi Materials Corporation) 0.14 parts methyl stearate (Tokyo Chemical Industry Co., Ltd.) 0.08 parts methyl palmitate (Tokyo Chemical Industry Co., Ltd.) Dimethyl glutaconate (Fujifilm Wako Pure Chemical Industries, Ltd.) 0.08 parts These were dispersed in 70 parts of 2-propanol to prepare ITO dispersion liquid 5.

[0096] [Preparation of SnO2 dispersion] 59.7 parts SnO2 particles (product name: T-1, manufactured by Mitsubishi Materials Corporation) Oleic acid amide (Tokyo Chemical Industry Co., Ltd.) 0.2 parts Methyl stearate (Tokyo Chemical Industry Co., Ltd.) 0.04 parts 0.03 parts methyl palmitate (Tokyo Chemical Industry Co., Ltd.) Dimethyl glutaconate (Fujifilm Wako Pure Chemical Industries, Ltd.) 0.03 parts These were dispersed in 140 parts of 2-propanol to prepare a SnO2 dispersion.

[0097] [TiO2 dispersion] TiO2 particles (rutile-type titanium oxide particles (average primary particle size: 50 nm), manufactured by Teika) 89.7 copies Oleic acid amide (Tokyo Chemical Industry Co., Ltd.) 0.2 parts Methyl stearate (Tokyo Chemical Industry Co., Ltd.) 0.04 parts 0.03 parts methyl palmitate (Tokyo Chemical Industry Co., Ltd.) Dimethyl glutaconate (Fujifilm Wako Pure Chemical Industries, Ltd.) 0.03 parts These were dispersed in 210 parts of 2-propanol to prepare a TiO2 dispersion.

[0098] [Preparation of protective layer coating solution 1] The following materials were prepared: 100 parts of ACM2 (Ebecryl E8301, manufactured by Daicel-Allnex Co., Ltd.) as a (meth)acrylic compound ·ITO dispersion 1:38 parts Crosslinkable polyester-modified polydimethylsiloxane with acryloyl groups (BYK-UV3570, manufactured by BYK-CHEMIE): 0.71 parts Oleic acid amide (Tokyo Chemical Industry Co., Ltd.) 0.64 parts These were dissolved in 420 parts of ethanol to prepare a protective layer coating solution 1.

[0099] [Preparation of protective layer coating solutions 2 to 34] Protective layer coating solutions 2 to 34 were prepared in the same manner as protective layer coating solution 1, except that the types and ratios of the ingredients were changed or added as shown in Table 1.

[0100] [Preparation of Protective Layer Coating Solution 35] Phenolic resin (phenolic resin monomer / oligomer) as a binder (trade name: Plyofen J-325, manufactured by DIC Corporation, resin solid content: 60%): 166.67 parts ·ITO dispersion 1:38 parts Polyester-modified polydimethylsiloxane (BYK-310, manufactured by BYK-CHEMIE): 0.71 parts Oleic acid amide (Tokyo Chemical Industry Co., Ltd.) 0.64 parts These were dissolved in 353.33 parts of 1-methoxy-2-propanol to prepare a coating solution for the protective layer.

[0101] [Table 1]

[0102] The volume resistivity of each metal oxide particle used in Table 1 was measured according to the <Method for measuring volume resistivity of metal oxide particles>, and the results are shown in Table 2.

[0103] [Table 2]

[0104] In Tables 1 and 2, "ITO" represents "indium tin oxide," "SnO2" represents "tin (II) oxide," and "TiO2" represents "titanium (IV) oxide (titania)."

[0105] <Production of electrophotographic photoreceptors> (Production Example of Electrophotographic Photoreceptor 1) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 257 mm and a diameter of 24 mm, manufactured by a manufacturing method including an extrusion process and a drawing process, was prepared. This was then cut using a sintered diamond tool. In the cleaning process, the cylinder was degreased, etched with a 2% by mass sodium hydroxide solution for 1 minute, neutralized, and then washed with pure water in this order.

[0106] Next, in a 10% by mass sulfuric acid solution, a current density of 1.0 A / dm 2Anodization was performed at 80°C for 20 minutes to form an anodized film on the cylinder surface. Next, after rinsing with water, the cylinder was immersed in a 1% by mass nickel acetate solution at 80°C for 15 minutes for pore sealing. Further rinsing with pure water and drying were performed to obtain an anodized support. The coating liquid for the charge generating layer was dip coated onto the support to form a coating film, and the coating film was dried by heating at 100° C. for 15 minutes to form a charge generating layer having a thickness of 0.24 μm.

[0107] Next, the charge transport layer coating liquid 1 was dip coated onto the charge generation layer to form a coating film, and the coating film was dried by heating at 120°C for 1 hour to form a charge transport layer with a thickness of 18 μm. Next, the protective layer coating solution 1 was dip-coated onto the charge transport layer to form a coating film, which was then irradiated with an electron beam at a dose of 86 kGy and allowed to cool naturally in the atmosphere until the temperature of the coating film reached 25° C. Thereafter, the coating film was heat-treated for 1 hour under conditions that brought the temperature of the coating film to 120° C., forming a protective layer with a thickness of 1.5 μm. The heat treatment of the coating film of each layer was carried out using an oven set to the respective temperature. In this manner, a cylindrical (drum-shaped) electrophotographic photoreceptor 1 was produced.

[0108] (Production Examples of Electrophotographic Photoreceptors 2 to 36, 38) Electrophotographic photoreceptors 2 to 36 and 38 were produced in the same manner as in the production example of electrophotographic photoreceptor 1, except that in the production example of electrophotographic photoreceptor 1, the types of coating liquids for the photosensitive layer and the protective layer were changed as shown in Table 3. In addition, in Table 3, electrophotographic photoreceptors for which no protective layer is shown do not have a protective layer formed, and the photosensitive layer serves as the surface layer.

[0109] (Production Example of Electrophotographic Photoreceptor 37) An electrophotographic photoreceptor 37 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the protective layer was formed in the following manner. [Method for forming protective layer on electrophotographic photoreceptor 37] The charge transport layer was dip-coated with Coating Solution 37 for the charge transport layer, and the resulting coating was dried and heat-cured at 150° C. for 30 minutes to form a first protective layer having a thickness of 1.5 μm.

[0110] <Sampling of the surface layer of an electrophotographic photoreceptor> The surface layer of the electrophotographic photosensitive member was sampled using a micromanipulator (Axis Pro SS, manufactured by Micro Support Co., Ltd.) It was confirmed that the sampling depth was the same as the film thickness of the surface layer.

[0111] <Measurement of specific gravity of surface layer> The specific gravity of the sampled surface layer was measured by the pycnometer (liquid phase displacement) method using butanol as a dispersion solvent.

[0112] <Measuring the content of metal particles in the surface layer> The ratio of the volume of metal oxide particles to the total volume of the surface layer was calculated from the amount of monomer with polymerizable functional groups and particles added in the surface layer coating solution, as well as their density and true specific gravity. The specific gravity of the polymer and particles after polymerization of the monomer with polymerizable functional groups can be determined from published values ​​provided by the manufacturer of each material and in the POLYINFO database of the National Institute for Materials Science.

[0113] When determining the amount of the electrophotographic photosensitive member, the following method can be used. The cross-sections of the electrophotographic photoreceptors prepared in the examples were observed. The samples for cross-section observation were obtained by dividing the electrophotographic photoreceptor into four equal parts in the longitudinal direction and sampling at positions ¼, ½, and ¾ of the length from the end, offset by 120° in the circumferential direction. 5 mm square sample pieces were cut out from each electrophotographic photoreceptor, and the surface layer was three-dimensionally processed to 2 μm × 2 μm × 2 μm using a FIB-SEM Slice & View.

[0114] The conditions for Slice&View were as follows: Sample processing for analysis: FIB method Processing and observation equipment: SII / Zeiss NVision40 Slice spacing: 5 nm (observation conditions) Accelerating voltage: 1.0 kV Sample tilt: 54° WD: 5mm Detector: BSE detector Aperture: 60μm, high current ABC:ON Image resolution: 1.25nm / pixel

[0115] The measurement environment is a temperature of 23° C. and a pressure of 1×10 −4 Pa. As a processing and observation device, a Strata400S (sample tilt: 52°) manufactured by FEI can also be used.

[0116] The analysis area was 2 μm long x 2 μm wide, and the information for each cross section was integrated. The surface of the surface layer was analyzed using a 2 μm long x 2 μm wide x 2 μm thick (8 μm 3 ) to calculate the volume V per unit area. Image analysis for each cross section is performed using image processing software: Media This was performed using Image-Pro Plus manufactured by Cybernetics.

[0117] The particle content in the total volume of the surface layer was calculated from the difference in contrast of the FIB-SEM Slice & View. In addition, based on the information obtained from image analysis, a volume of 2 μm × 2 μm × 2 μm (unit volume: 8 μm) was calculated for each of the four sample pieces. 3 ) and calculate the particle content [volume %] (= V μm3 / 8 μm 3 × 100) was calculated. The average value of the particle content values ​​in each sample piece was taken as the content V [vol %] of each particle of the present invention in the surface layer relative to the total volume of the surface layer.

[0118] The specific gravity α of the surface layer calculated above, the content V [vol %] of metal oxide particles in the surface layer relative to the total volume of the surface layer, and the specific gravity γ of the metal oxide particles M The specific gravity of the resin part excluding the metal oxide on the surface is γ r Since the following formula 1 holds, the specific gravity of the surface layer α and the specific gravity of the metal oxide particles γ M and the content of metal oxide particles V [volume %], the specific gravity γ of the part [resin part] excluding the metal oxide of the surface layer rThe identification of metal oxide particles will be described later, but the published values ​​in the POLYINFO database of the National Institute for Materials Science were used for the specific gravity. α = V × γ M + (1-V)×γ r (Formula 1)

[0119] <hs-gcms> The surface layer sampled from the electrophotographic photoreceptor was weighed in advance (X g), placed in a headspace vial, and sealed with a septum. The sealed headspace vial was heated under the conditions described below, and the vaporized oleic acid amide was measured using GC / MS under the conditions described below. The peak area where oleic acid amide was detected in the resulting total ion chromatogram was determined. A calibration curve was created using a solution of oleic acid amide dissolved in methanol as the standard substance for the calibration curve, and the detected amount of oleic acid amide (A (g)) was calculated from the peak area. The detected amount (A (g)) was divided by the cut-out sample weight (X (g)) to calculate the oleic acid amide content (A / X (%)).

[0120] [Pretreatment conditions] <Headspace sampler conditions> Triplus300 (Thermo Fisher Scientific), heating temperature: 150°C, holding time: 60 minutes, number of measurements: 1 <GC / MS analysis conditions> GC: TRACEGC1310, MS: ISQ-LT, Carrier gas: He, Injection method: Split (split flow 20 mL / min), Column flow rate: 1 mL / min (constant flow mode), Separation column: DB-5MS (length: 60 m, inner diameter: 0.25 mm, film thickness: 0.25 μm), Oven temperature: 40 °C for 3 min, then heated to 70 °C at a rate of 2 °C / min, then heated to 150 °C at a rate of 5 °C / min, then heated to 300 °C at a rate of 10 °C / min, and then held at 300 °C for 1 min. MS: Ionization chamber temperature: 250 °C, Ionization method: EI, Ionization voltage: 70 eV, Measurement mode: Scan, Mass range: m / z = 25-401, GC / MS interface temperature: 250 °C

[0121] < 1 H-NMR analysis> The weight of the surface layer sampled from the electrophotographic photoreceptor was measured in advance (×2 g), and then the surface layer was immersed in chloroform so that the entire surface layer was immersed and left to stand for 10 minutes, thereby dissolving all of the polyester-modified polydimethylsiloxane formed on the surface layer. The solution was evaporated to dryness under reduced pressure, and 1 g of deuterated chloroform containing tetramethylsilane as an internal standard (chloroform-d, 99.8 atom% D, contains 0.05% (v / v) TMS, manufactured by Sigma-Aldrich Japan Co., Ltd.) was added thereto, and the dried product was completely dissolved by shaking and stirring for 5 minutes. This solution was transferred to a glass NMR sample tube (Norell ST500-7) with an outer diameter of 5 mm, and proton NMR measurement was performed. The NMR instrument used was a Bruker AVANCE500. The measurement conditions were automatic measurement by ICON-NMR, with the exception of setting the number of accumulations to 32 and the rotation speed to 20 Hz. In the obtained spectrum, the chemical shift value of the peak of the methyl group of tetramethylsilane was corrected to 0 ppm.

[0122] The detected amount of polyester-modified polydimethylsiloxane (B(g)) was calculated from the peak intensity ratio with respect to the internal standard substance, tetramethylsilane. The detected amount (B(g)) was divided by the cut-out sample weight (X2(g)) to calculate the polyester-modified polydimethylsiloxane content (B / X2(%)).

[0123] <Method for identifying (meth)acrylic compounds> The electrophotographic photoreceptor used in the present invention can be identified as having a surface layer formed by polymerizing a composition containing the (meth)acrylic compound as described above, as follows: Furthermore, the structural formulas of the multiple types of (meth)acrylic monomers and / or (meth)acrylic oligomers and the content ratios thereof can be identified as described below.

[0124] (1) The electrophotographic photoreceptor is immersed in chloroform. Since the surface layer formed by polymerizing the (meth)acrylic compound is insoluble in chloroform, the surface layer is separated from the electrophotographic photoreceptor in chloroform, and a chloroform solution is obtained in which the layer below the surface layer has dissolved.

[0125] (2) The solution is analyzed using chromatography, accurate mass spectrometry, nuclear magnetic resonance spectroscopy, pyrolysis gas chromatography, etc., thereby identifying the multiple types of unreacted (meth)acrylic monomers and / or (meth)acrylic oligomers contained in the layer below the surface layer.

[0126] (3) A certain amount of each of the above-identified (meth)acrylic monomers and / or (meth)acrylic oligomers is prepared by synthesis or purchase, and polymerized as a single unit.

[0127] (4) The above-mentioned polymerized products are each analyzed by infrared absorption spectroscopy, and a calibration peak is determined as a peak to be used to obtain a calibration curve in the obtained infrared absorption spectrum. At this time, the calibration peak of each (meth)acrylic monomer is selected so that the peak intensity is maximized under the condition that the calibration peak of any polymer other than itself does not fall within a range three times the half-width of the calibration peak.

[0128] (5) For each polymer, a calibration range is determined, which is defined as a range three times the half-width centered on the calibration peak.

[0129] (6) At least two or more unreacted (meth)acrylic monomers and / or (meth)acrylic oligomers are mixed in a mixing ratio of at least two or more and polymerized, and the infrared absorption spectrum is measured. Then, the integrated values ​​in the above calibration range are compared to obtain a calibration curve for each (meth)acrylic monomer and / or (meth)acrylic oligomer.

[0130] (7) The surface layer of the electrophotographic photoreceptor to be identified is analyzed by infrared absorption spectroscopy. From the obtained infrared absorption spectrum-1 and the calibration curves of each (meth)acrylic monomer and / or (meth)acrylic oligomer, the mixing ratio of each (meth)acrylic monomer and / or (meth)acrylic oligomer contained in the surface layer is calculated.

[0131] (8) The respective (meth)acrylic monomers and / or (meth)acrylic oligomers are mixed in the above mixing ratio and polymerized, and the infrared absorption spectrum-2 of the polymer is measured.

[0132] (9) Compare the infrared absorption spectrum-1 with the infrared absorption spectrum-2. At this time, confirm that the integral value of the difference spectrum in the calibration range of each (meth)acrylic monomer and / or (meth)acrylic oligomer is 10% or less of the integral value in the calibration range of the infrared absorption spectrum-2.

[0133] Note that steps (1) and (2) in the above identification method can be replaced by component identification using other methods, including literature research. Furthermore, it is sufficient to finally confirm in step (9) above that the surface layer to be identified is indeed polymerized from multiple types of (meth)acrylic monomers and / or (meth)acrylic oligomers that are candidates for identification. To this extent, steps (1) and (2), as well as steps (3) to (8), can also be replaced by other methods.

[0134] <Method for identifying metal oxide particles> When the surface layer of the electrophotographic photosensitive member used in the present invention contains metal oxide particles, the composition of the metal oxide particles and the content ratio of the metal oxide particles to the surface layer can be identified as follows.

[0135] (Identification of composition) (1) A cross section of the surface layer of an electrophotographic photosensitive member is cut out and observed under a scanning electron microscope. (2) Energy dispersive X-ray analysis is performed on particles present in the observation area to identify their composition.

[0136] (Identification of content ratio) (1) Immerse the electrophotographic photosensitive member in chloroform. Since the surface layer formed by polymerizing the (meth)acrylic compound is insoluble in chloroform, the surface layer is separated from the electrophotographic photosensitive member in chloroform. (2) The separated surface layer is washed, dried, and subjected to thermogravimetric analysis. (3) The content ratio is identified by comparing the weight at low temperature with the weight at high temperature after all organic matter has been burned.

[0137] <Method for measuring volume resistivity of metal oxide particles> The volume resistivity of the metal oxide particles can be evaluated by measuring the capacitance and conductivity of the air and the powder by impedance measurement using a parallel plate capacitor method.

[0138] The equipment used is a powder measurement jig consisting of a four-terminal sample holder SH2-Z (manufactured by Toyo Corporation) and a torque wrench adapter SH-TRQ-AD (manufactured by Toyo Corporation, optional), and a materials testing system ModuLabXMMTS (manufactured by Solartron).In addition, a noise-cutting transformer NCT-I31.4kVA (manufactured by Denken Seiki Kenkyusho Co., Ltd.) is used to suppress commercial power supply noise, and a shielding box is used to suppress electromagnetic noise.

[0139] The powder measurement jig uses a four-terminal sample holder and the optional torque wrench adapter SH-TRQ-AD. The parallel plate electrodes used are the upper electrode (Φ25mm solid electrode) SH-H25AU and the lower electrode for liquids / powder (center electrode Φ10mm; guard electrode Φ26mm) SH-2610AU. This configuration allows resistance measurements of 0.1Ω to 1TΩ for electrical signals of up to 500Vp-p and DC to AC 1MHz. In addition, to adjust the pressure of the powder sample, a torque wrench adapter SH-TRQ-AD is attached to the micrometer used to measure the film thickness between the upper and lower electrodes provided on the four-terminal sample holder. Torque drivers used for pressure control are torque drivers RTD15CN and RTD30CN (manufactured by Tohnichi Manufacturing Co., Ltd.) and a 6.35 mm square bit, and are configured to be able to control the tightening torque of the metal oxide particles to 20.0 cN / m.

[0140] To measure the electrical AC characteristics, impedance measurements are performed using the ModuLabXMMTS material testing system (manufactured by Solartron). ModuLabXMMTS consists of a control module XMMAT1MHz, a high-voltage module XMMHV100, a femtocurrent module XMMFA, and a frequency response analysis module XMMRA1MHz. The control software used is Solartron's XM-studioMTSVer.3.4.

[0141] The measurement conditions for metal oxide particles are set to Normal Mode, which only performs measurement. The AC level is set to 7 x 10 so that it falls within the measurable current range of the measuring instrument. -3 Set it within the range of 7Vrms or more. In addition, the DC bias is set to 0 V, and the sweep frequency is set to 1 MHz to 0.01 Hz (12 points / decade or 6 points / decade). In the case of highly conductive powder materials such as external additives, the AC level is set to 7 x 10 so that it falls within the measurable current range of the measuring instrument. -3 Set it within the range of 7Vrms or more.

[0142] Furthermore, in consideration of noise suppression and shortening of measurement time, the following settings are added for each sweep frequency. Sweep frequency 1MHz to 10Hz: Measurement integration time 64 cycles Sweep frequency 10Hz to 1Hz: Measurement integration time 24 cycles Sweep frequency 1Hz to 0.01Hz: Measurement integration time 1 cycle

[0143] Under the above measurement conditions, the impedance characteristics, which are electrical AC characteristics, are measured. By performing measurements under the above conditions and using a powder measurement jig based on the parallel plate capacitor method, the impedance characteristics of the air and sample at a film thickness d corresponding to a Φ10 mm measurement electrode S and pressure torque can be obtained.

[0144] From the obtained impedance characteristics of the air and sample, data correction processing for the measurement system is performed to obtain highly reliable capacitance C and conductance (electrical conductivity) G. From the obtained capacitance C, conductance (electrical conductivity) G, and the geometric shape of the powder measurement jig (parallel plate electrode size S and sample film thickness), the electrical properties of relative permittivity and electrical conductivity are calculated.

[0145] When using the SH2-Z four-terminal sample holder for the first time, because there are individual differences between the SH2-Z four-terminal sample holders used in powder measurement jigs, it is necessary to carry out the following two verifications to find the optimal measurement conditions. The first verification is the film thickness dependency characteristics of the four-terminal sample holder. The dependency on air thickness (distance between the upper and lower electrodes) is measured, the error between the theoretical value of capacitance and the measured value is confirmed, and the optimal range or film thickness at which the measurement error is minimized is identified. The second verification was the measurement of mechanical error. When measuring powder samples, a torque-controlled load was applied to keep the volume density constant. In contrast, when measuring air, no load was applied. At this time, film thickness errors occur due to the influence of dimensions such as mechanical processing accuracy. Therefore, the offset value of the tightening torque control value (6.5 cN m in this jig) is confirmed under load and no load conditions, and this is used as the offset correction value.

[0146] The specific sample preparation and measurement procedures are as follows. (1) A powder sample is placed on the center electrode of the lower electrode and formed into a trapezoidal shape with a height of 5 mm. (2) The lower electrode carrying the powder sample is attached to the four-terminal sample holder SH2-Z, and the upper electrode is lowered.

[0147] (3) At this time, the upper electrode is lowered to the top end of the powder sample while keeping it constant so as not to rotate inadvertently. (4) While rotating the upper electrode left and right, smoothing treatment is performed to make the powder sample smooth.

[0148] (5) Using a micrometer, adjust the film thickness to a predetermined value while maintaining the rotation direction of the upper electrode in a uniform, constant direction. (6) Apply pressure using a torque driver with a tightening torque controlled to 20.0 cN·m.

[0149] (7) Using a micrometer, measure the film thickness of the powder sample. (8) Impedance measurement is carried out under the above conditions.

[0150] (9) After the measurement is completed, raise the upper electrode and remove the lower electrode. At this time, remove the lower electrode carefully so that the powder sample does not get into the contact terminal for the lower electrode of the four-terminal sample holder, and protect it with masking tape. (10) Clean the upper and lower electrodes.

[0151] (11) Remove the masking tape and attach the lower electrode. (12) The sample film thickness d obtained in step (7) is adjusted to the air thickness t, taking into account offset correction in the no-load state, and the rotation direction of the upper electrode is kept constant.

[0152] (13) Conduct air impedance measurements. (14) If the measurement data (dielectric tangent; tanδ) of the air measured in step (13) is greater than 0.001 in the frequency range of 100 Hz to 0.021 Hz, the cleaning is insufficient, so the work is started again from the cleaning step (10). The measurement is carried out at 25°C. The specific data processing procedure is as follows.

[0153] (15) From the measured impedance characteristics of air, the error of the phase characteristics relative to the theoretical value is calculated, and phase correction data for the material testing system ModuLabXMMTS (manufactured by Solartron) is obtained. (16) The phase correction data calculated in step (15) is applied to the impedance characteristics of the air measured in step (13) to obtain the phase-corrected impedance characteristics of the air.

[0154] (17) The capacitance Ca is calculated from the admittance Ya=Ga+jωCa of the phase-corrected impedance characteristic of air, and the error from the theoretical value is calculated to obtain correction data α for the film thickness error. (18) The phase correction process obtained in step (15) is applied to the impedance characteristics of the powder sample measured in step (8).

[0155] (19) By calculating the complex admittance Ym = Gm + jωCm of the characteristics that have been subjected to the phase correction processing in step (18) using the capacitance Ca of the air obtained in step (17) and its correction data α, highly reliable relative permittivity and conductivity of the powder sample can be obtained.

[0156] The following describes a method for quantifying volume resistivity, an electrical property. (Method for quantifying the electrical conductivity index κ / ω) Generally, the electrical conductivity κ of a dielectric (insulator) is proportional to the angular frequency, so it is useful to use the electrical conductivity index κ / ω, which is the electrical conductivity κ divided by the angular frequency ω, as the electrical conductivity parameter value. The electrical conductivity index κ / ω exhibits frequency characteristics similar to the dielectric loss tangent tanδ, and when the dielectric relaxation of the electrode interface component and the powder bulk component differs, it exhibits characteristics with a maximum value. The maximum value of the conductivity index κ / ω is considered to indicate the conductivity of the powder bulk, including the particle interior, particle surface, and particle-particle interface. Therefore, this maximum value is defined as the conductivity parameter of the powder bulk component.

[0157] (Methods for quantifying electrical conductivity and volume resistivity) A powder sample that has both capacitance and conductivity can be recognized as an RC parallel circuit model, and the conductivity κ in the low frequency range shows a constant value. The reciprocal of this conductivity κ is defined as the volume resistivity.

[0158] <Measurement of Martens hardness of the surface layer> The Martens hardness of the surface layer was measured using a microhardness measuring device (product name: Picodentor HM500, manufactured by Fisher Instruments Inc.) and a microscope attached to this device. Specifically, the Martens hardness was measured in an environment of 25°C / 50%RH using a microscope attached to a microhardness tester. A square pyramidal diamond indenter was placed on the core portion identified by a confocal microscope during observation of the hollow particles, and the indenter was pressed at a pressing speed according to the following calculation formula (1), with a maximum contact pressure of 0.5 mN, and the particles were allowed to creep for 5 seconds. Calculation formula (1) dF / dt=0.5 mN / 10s In equation (1), F represents force and t represents time. The Martens hardness was measured after a creep time of 5 seconds. Measurements were taken at 10 points, and the extracted values ​​were averaged to obtain the average Martens hardness of the surface layer.

[0159] [Table 3]

[0160] [Table 4]

[0161] <Evaluation method> <Method for evaluating image blur> The examples and comparative examples were evaluated by the following evaluation methods. A photoreceptor tester (product name: CYNTHIA59, manufactured by Gentec Co., Ltd.) was used. The electrophotographic photoreceptors according to the examples and comparative examples were placed in the photoreceptor tester in an environment of a temperature of 32.5°C and a humidity of 80% RH, and aged for 24 hours or more. A conductive rubber roller having a diameter of 8 mm was used as a charging member, and the charging device was set so that a square-wave voltage with a frequency of 1 Hz, Voffset=-450 V, and Vpp=500 V could be applied to the surface of the electrophotographic photosensitive member. In measuring the potential, a surface potential probe (model 6000B-8, manufactured by Trek Japan Co., Ltd.) was placed at a position 1 mm away from the electrophotographic photosensitive member, and a surface potential meter (model 344, manufactured by Trek Japan Co., Ltd.) was used.

[0162] The initial charge retention was determined according to the following procedures 1 to 4. Step 1: While rotating the electrophotographic photosensitive member at a rotation speed of 30 rpm under an environment of a temperature of 32.5°C and a humidity of 80% RH, a voltage is applied to the surface of the electrophotographic photosensitive member from one direction. The voltage is a square wave with a frequency of 1 Hz, Voffset=-450 V, and Vpp=1000 V.

[0163] Step 2: At a position where the portion of the surface of the electrophotographic photosensitive member to which the voltage has been applied has rotated for 0.30 seconds, the potential of the surface of the electrophotographic photosensitive member is measured for a fixed time of 10 seconds to 20 seconds at measurement intervals of 100 μs.

[0164] Step 3: Plot the values ​​obtained by the measurement with the horizontal axis in μs and the vertical axis in V, and for each measurement point, determine the slope of the regression line derived from the previous 25 measurement points and the slope of the regression line derived from the next 25 measurement points.

[0165] Step 4: Of the obtained slope values, the absolute values ​​of the maximum and minimum values ​​are averaged to obtain a value that is regarded as the charge retention property.

[0166] In step 3 above, the first 24 points obtained from the start of measurement and the last 24 points obtained before the end of measurement are not used as data for determining the slope because there are fewer than 25 measurement points for deriving a regression line.

[0167] Thereafter, the electrophotographic photosensitive member is subjected to discharge idle rotation for 10 minutes under the following conditions: While rotating the electrophotographic photosensitive member at 60 rpm, a voltage is applied to the surface of the electrophotographic photosensitive member, and the voltage is a square wave with a frequency of 1.4 kHz, Voffset=-450 V, and Vpp=1300 V. After the discharge idle rotation is performed, the charge retention after discharge deterioration is measured again according to the above procedures 1 to 4 in the same manner as in the measurement of the initial charge retention. The value obtained by subtracting the charge retention property after discharge deterioration from the initial charge retention property was calculated as an image blur suppression index. The results are shown in Table 5.

[0168] <Cleaning performance evaluation> For the evaluation of cleaning performance, a laser beam printer manufactured by Hewlett-Packard (product name: Color Laser Jet Enterprise M653dn) and a process cartridge equipped with the electrophotographic photosensitive member used in this study, as shown in the schematic diagram of FIG. 3, were used. In an environment with a temperature of 15.0°C and a relative humidity of 10%, the charging potential was set to -550V, the exposure potential was set to -100V, and 10,000 sheets of 1% black toner print images were continuously printed. The first sheet and every 1,000 sheets, a total of 11 images, were evaluated according to the following evaluation criteria. Evaluation criteria up to C are considered to be at a level that is acceptable for practical use. The evaluation results are shown in Table 4.

[0169] (Evaluation criteria) A: Visual observation revealed no streaky images extending in the process direction in any of the 11 images. B: Visual observation revealed that in all 11 images, there were 5 or fewer streak-like images extending in the process direction, and all of them were 5 mm or less in length. C: Visual observation revealed that in all 11 images, there were 5 or fewer streak-like images extending in the process direction, and some of the images were longer than 5 mm. D: More than five streak-like images extending in the process direction can be confirmed by visual observation in all 11 images.

[0170] <Charging roller contact streaks evaluation> The charging roller pitch streaks were evaluated using a Hewlett-Packard laser beam printer (product name: Color Laser Jet Enterprise M653dn) and a process cartridge shown in the schematic diagram of FIG. 2, which was equipped with the electrophotographic photosensitive member used in this study.

[0171] The process cartridge equipped with the electrophotographic photosensitive member used in this study was placed in a sealed bag and placed in an environment with a temperature of 40°C and a relative humidity of 95%. Two hours after placement, the bag was opened and left for a further seven days, and then left in an environment with a temperature of 25°C and a relative humidity of 50% for 24 hours. Markings were made on the charging roller and the electrophotographic photosensitive member with a marker so that the contact points between the charging roller and the electrophotographic photosensitive member could be determined. After that, in order to output an evaluation image, the voltage applied to the charging roller was first set so that the surface potential of the electrophotographic photosensitive member was -550 V, and a halftone image (toner amount: 0.2 mg / cm) with black toner and margins of 5.0 mm on all four sides was printed. 2 ) was printed. The evaluation of the charging roller contact streak images of the halftone images was carried out according to the following evaluation criteria. Evaluation criteria A to C are levels that are practically problem-free. The evaluation results are shown in Table 5.

[0172] (Evaluation criteria) A: No stripes at the charging roller pitch are observed on the image by visual inspection. B: By visual observation, a very slight part of the contact portion between the charging roller and the electrophotographic photosensitive member is observed on the image, but it cannot be confirmed on the outer periphery of the charging roller or the electrophotographic photosensitive member. C: By visual observation, a very small part of the contact area between the charging roller and the electrophotographic photosensitive member is observed on the image, and can be confirmed at the circumferential pitch of the charging roller or the electrophotographic photosensitive member. D: By visual observation, a part of the contact portion between the charging roller and the electrophotographic photosensitive member is observed on the image, and can be confirmed at the peripheral pitch of the charging roller or the electrophotographic photosensitive member. E: By visual observation, almost the entire contact area between the charging roller and the electrophotographic photosensitive member is observed on the image, and can be confirmed at the circumferential pitch of the charging roller or the electrophotographic photosensitive member.

[0173] [Table 5]

[0174] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) An electrophotographic photoreceptor having a surface layer containing a binder resin, The electrophotographic photoreceptor is characterized in that the surface layer contains a polydimethylsiloxane component having a polyester chain and oleic acid amide. (Configuration 2) the surface layer is a protective layer, 2. The electrophotographic photoreceptor according to claim 1, wherein the protective layer is a polymer film of a composition containing at least one (meth)acrylic compound selected from the group consisting of (meth)acrylic monomers and (meth)acrylic oligomers. (Configuration 3) 3. The electrophotographic photoreceptor according to claim 2, wherein the polydimethylsiloxane having a polyester chain is a part of a polymer film in the protective layer. (Configuration 4) 4. The electrophotographic photoreceptor according to any one of Configurations 1 to 3, wherein the composition containing the (meth)acrylic compound includes at least one selected from the group consisting of a hexafunctional urethane acrylic monomer and a hexafunctional urethane acrylic oligomer. (Configuration 5) The Martens hardness of the surface layer is 150 N / mm 2 More than 300N / mm 2 5. An electrophotographic photoreceptor according to any one of the following configurations 1 to 4. (Configuration 6) The electrophotographic photoreceptor according to any one of Configurations 1 to 5, wherein the surface layer contains metal oxide particles. (Configuration 7) 7. The electrophotographic photoreceptor according to claim 6, wherein the metal oxide particles contain tin atoms. (Configuration 8) 8. The electrophotographic photoreceptor according to claim 6, wherein the metal oxide particles are ITO particles. (Configuration 9) 9. The electrophotographic photoreceptor according to any one of Configurations 1 to 8, wherein the amount of the oleic acid amide added is 40 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the polyester chain-having polydimethylsiloxane. (Configuration 10) 10. The electrophotographic photoreceptor according to any one of configurations 1 to 9, wherein the polydimethylsiloxane having a polyester chain is a polyester-modified polydimethylsiloxane. (Configuration 11) 11. The electrophotographic photoreceptor according to any one of configurations 1 to 10, wherein the polydimethylsiloxane having a polyester chain is a compound represented by the following formula (B): [ka] (In the formula (B), R 1 is an aliphatic hydrocarbon group having 1 to 15 carbon atoms, and R 2 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R 3 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R 4 represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group having from 1 to 15 carbon atoms, x represents an integer of 1 to 300, y represents an integer of 1 to 100, j represents an integer of 1 to 15, k represents an integer of 0 to 5, and m represents an integer of 1 to 20. (Configuration 12) A process cartridge integrally supporting the electrophotographic photosensitive member according to any one of Configurations 1 to 11 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and being detachably mountable to the main body of an electrophotographic apparatus. (Configuration 13) 12. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of Configurations 1 to 11, as well as a charging means, an exposing means, a developing means, and a transferring means. (Method 1) A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising: a preparation step of preparing a coating liquid for the surface layer; a coating step of coating the coating liquid; a solidification step of solidifying the applied coating liquid by drying or curing, The method for producing an electrophotographic photoreceptor, wherein the coating liquid contains polydimethylsiloxane having a polyester chain and oleic acid amide. [Explanation of symbols]

[0175] 11 Support 12 Undercoat layer 13 Charge generation layer 14 Charge transport layer 15 Surface layer 1 Photosensitive drum 2 Charging roller 4 Development unit 7 Cleaning material 8 Rubber Blades 9 Cleaning support member 25 Developing roller 27 Toner removal chamber 31 Developing frame 34 Toner supply roller 70 Process cartridge

Claims

1. An electrophotographic photoreceptor having a surface layer containing a binder resin, The electrophotographic photoreceptor is characterized in that the surface layer contains polydimethylsiloxane having a polyester chain and oleic acid amide.

2. the surface layer is a protective layer, 2. The electrophotographic photoreceptor according to claim 1, wherein the protective layer is a polymer film of a composition containing at least one (meth)acrylic compound selected from the group consisting of (meth)acrylic monomers and (meth)acrylic oligomers.

3. 3. The electrophotographic photoreceptor according to claim 2, wherein the polydimethylsiloxane having polyester chains is a part of a polymer film in the protective layer.

4. 3. The electrophotographic photoreceptor according to claim 2, wherein the composition containing a (meth)acrylic compound comprises at least one selected from the group consisting of a hexafunctional urethane acrylic monomer and a hexafunctional urethane acrylic oligomer.

5. The Martens hardness of the surface layer is 150 N / mm ２ More than 300N / mm ２ 2. The electrophotographic photoreceptor according to claim 1, wherein:

6. The electrophotographic photoreceptor according to claim 1 , wherein the surface layer contains metal oxide particles.

7. The electrophotographic photoreceptor according to claim 6 , wherein the metal oxide particles contain tin atoms.

8. 7. The electrophotographic photoreceptor according to claim 6, wherein the metal oxide particles are ITO particles.

9. 2. The electrophotographic photoreceptor according to claim 1, wherein the amount of the oleic acid amide added is 40 parts by mass or more and 160 parts by mass or less per 100 parts by mass of the polydimethylsiloxane having a polyester chain.

10. 2. The electrophotographic photoreceptor according to claim 1, wherein the polydimethylsiloxane having a polyester chain is a polyester-modified polydimethylsiloxane.

11. 2. The electrophotographic photoreceptor according to claim 1, wherein the polydimethylsiloxane having a polyester chain is a compound represented by the following formula (B): 【Chemical 1】 (In the formula (B), R １ is an aliphatic hydrocarbon group having 1 to 15 carbon atoms, and R ２ is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R ３ is an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 15 carbon atoms, and R ４ represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group having from 1 to 15 carbon atoms, x represents an integer of 1 to 300, y represents an integer of 1 to 100, j represents an integer of 1 to 15, k represents an integer of 0 to 5, and m represents an integer of 1 to 20.

12. 12. A process cartridge that 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.

13. 12. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit.

14. A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising: a preparation step of preparing a coating liquid for the surface layer; a coating step of coating the coating liquid; a solidification step of solidifying the applied coating liquid by drying or curing, The method for producing an electrophotographic photoreceptor, wherein the coating liquid contains polydimethylsiloxane having a polyester chain and oleic acid amide.

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