Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention discloses an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. The electrophotographic photoreceptor includes: a conductive substrate; a charge generation layer which is provided on the conductive substrate; a charge transport layer disposed on the charge generation layer, the charge transport layer including inorganic oxide particles; and an inorganic protective layer, the charge generation layer and the charge transport layer forming a photosensitive layer, the inorganic protective layer being provided on the photosensitive layer, and the inorganic protective layer having a thickness of 1 / 2 of a film thickness of the charge transport layer as a boundary in a cross-sectional view of the charge transport layer. The relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies the area ratio Agt; and area ratio B.

Description

Technical Field

[0001] The present invention relates to an electronic photographic photoreceptor, a processing box and an image forming device. Background Art

[0002] Japanese Patent Gazette No. 2020-008688 discloses "an electronic photographic photoreceptor comprising: a conductive substrate; an undercoat layer, which is arranged on the conductive substrate and is composed of a metal oxide layer; a charge generating layer, which is arranged on the undercoat layer; a charge transport layer, which is arranged on the charge generating layer and contains a binder resin, a charge transport material, and silica particles; and an inorganic protective layer, which is arranged on the charge transport layer and is composed of a metal oxide layer." Summary of the Invention

[0003] The object of the present invention is to provide an electronic photographic photosensitive body comprising: a conductive substrate; a charge generating layer, the charge generating layer being arranged on the conductive substrate; a charge transport layer, the charge transport layer being arranged on the charge generating layer and comprising inorganic oxide particles, the charge generating layer and the charge transport layer forming a photosensitive layer; and an inorganic protective layer, the inorganic protective layer being arranged on the photosensitive layer, wherein, compared with the following situation, while ensuring the crack resistance of the inorganic protective layer, the transmittance of the charge transport layer is improved: in cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same.

[0004] According to a first embodiment of the present invention, an electronic photographic photosensitive body is provided, comprising: a conductive substrate; a charge generating layer, the charge generating layer being arranged on the conductive substrate; a charge transport layer, the charge transport layer being arranged on the charge generating layer and comprising inorganic oxide particles, the charge generating layer and the charge transport layer forming a photosensitive layer; and an inorganic protective layer, the inorganic protective layer being arranged on the photosensitive layer, wherein, in a cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as a boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies the following: area ratio A>area ratio B.

[0005] According to a second aspect of the present invention, in the electrophotographic photoreceptor according to the first aspect, a difference between an area ratio A of the inorganic oxide particles contained in the surface layer and an area ratio B of the inorganic oxide particles contained in the inner layer is 1% or more and 75% or less.

[0006] According to a third aspect of the present invention, in the electrophotographic photoreceptor according to the second aspect, a difference between an area ratio A of the inorganic oxide particles contained in the surface layer and an area ratio B of the inorganic oxide particles contained in the inner layer is 20% or more and 75% or less.

[0007] According to the fourth embodiment of the present invention, in the electronic photographic photosensitive body involved in any one of the first to third embodiments, the area ratio A of the inorganic oxide particles contained in the surface layer is greater than 60% and less than 75%, and the area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%.

[0008] According to a fifth aspect of the present invention, in the electrophotographic photoreceptor according to the fourth aspect, an area ratio A of the inorganic oxide particles contained in the surface layer is 60% or more and 70% or less.

[0009] The area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%.

[0010] According to a sixth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to fifth aspects, the charge transport layer has a light transmittance of 80% or more.

[0011] According to a seventh aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to sixth aspects, the charge transport layer has a Young's modulus of 12 GPa or more.

[0012] According to an eighth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to seventh aspects, the inorganic oxide particles are silica particles.

[0013] According to a ninth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to eighth aspects, the inorganic protective layer is a layer containing a metal oxide.

[0014] According to a tenth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to ninth aspects, the inorganic protective layer is a layer containing gallium oxide.

[0015] According to an eleventh aspect of the present invention, there is provided a process cartridge including the electrophotographic photoreceptor according to any one of the first to tenth aspects, wherein the process cartridge is attachable to and detachable from an image forming apparatus.

[0016] According to the twelfth embodiment of the present invention, there is provided an image forming device comprising: the electronic photographic photoreceptor according to any one of the first to tenth embodiments; a charging device for charging the surface of the electronic photographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electronic photographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electronic photographic photoreceptor using a developer containing a colorant to form a colorant image; and a transfer device for transferring the colorant image to the surface of a recording medium.

[0017] (Effect)

[0018] According to the first scheme, an electronic photographic photoreceptor is provided, which comprises: a conductive substrate; a charge generating layer, wherein the charge generating layer is arranged on the conductive substrate; a charge transport layer, which is arranged on the charge generating layer and contains inorganic oxide particles, wherein the charge generating layer and the charge transport layer form a photosensitive layer; and an inorganic protective layer, wherein the inorganic protective layer is arranged on the photosensitive layer, and the transmittance of the charge transport layer is improved while ensuring the crack resistance of the inorganic protective layer, compared with the following situation: in the cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same.

[0019] According to the second scheme, an electronic photographic photoreceptor is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is less than 1% or exceeds 75%.

[0020] According to the third scheme, an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is less than 20% or exceeds 75%.

[0021] According to the fourth scheme, an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer is less than 60% or exceeds 75%, or the case where the area ratio B of the inorganic oxide particles contained in the inner layer is greater than 60%.

[0022] According to the fifth scheme, an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer is less than 60% or exceeds 70%, or the case where the area ratio B of the inorganic oxide particles contained in the inner layer exceeds 60%.

[0023] According to the sixth aspect, an electrophotographic photoreceptor is provided in which the light transmittance of the charge transport layer is improved while ensuring the crack resistance of the inorganic protective layer, compared with a case where the light transmittance of the charge transport layer is less than 80%.

[0024] According to the seventh aspect, an electrophotographic photoreceptor is provided in which the light transmittance of the charge transport layer is improved while ensuring the crack resistance of the inorganic protective layer, compared with a case where the Young's modulus of the charge transport layer is less than 12 GPa.

[0025] According to the eighth scheme, an electronic photographic photosensitive body is provided, which contains silica particles in the charge transport layer, and improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0026] According to the ninth scheme, an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer containing metal oxide, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0027] According to the tenth scheme, an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer containing gallium oxide, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0028] According to the eleventh or twelfth scheme, a processing box or an image forming device is provided with an electronic photographic photosensitive body, wherein the electronic photographic photosensitive body comprises: a conductive substrate; a charge generating layer, wherein the charge generating layer is arranged on the conductive substrate; a charge transport layer, wherein the charge transport layer is arranged on the charge generating layer and comprises inorganic oxide particles, wherein the charge generating layer and the charge transport layer form a photosensitive layer; and an inorganic protective layer, wherein the inorganic protective layer is arranged on the photosensitive layer. Compared with the following situation, the processing box or the image forming device improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer: in the applied electronic photographic photosensitive body, in the cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment;

[0030] Figure 2 FIG. 1 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0031] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are for illustrative purposes only and do not limit the scope of the present invention.

[0033] In the present invention, a numerical range expressed using “to” indicates a range including the numerical values ​​described before and after “to” as the minimum value and the maximum value, respectively.

[0034] In the numerical range of recording in stages in the present invention, the upper limit or lower limit of recording in one numerical range can also be replaced by the upper limit or lower limit of the numerical range of recording in other stages. In addition, in the numerical range of recording in the present invention, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment.

[0035] In the present invention, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process can be achieved.

[0036] In the present invention, when the embodiments are described with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. In addition, the sizes of the components in the drawings are conceptual sizes, and the relative relationship between the sizes of the components is not limited to this.

[0037] In the present invention, each component may also include multiple corresponding substances. In the present invention, when the amount of each component in the composition is mentioned, if multiple substances equivalent to each component are present in the composition, the amount of each component refers to the total amount of the multiple substances present in the composition, unless otherwise specified.

[0038] In the present invention, multiple types of particles corresponding to each component may be included. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for the mixture of the multiple types of particles present in the composition unless otherwise specified.

[0039] In the present invention, unless otherwise specified, alkyl groups and alkylene groups include linear, branched, and cyclic groups.

[0040] In the present invention, hydrogen atoms in groups such as organic groups, aromatic rings, linking groups, alkyl groups, alkylene groups, aryl groups, aralkyl groups, alkoxy groups, and aryloxy groups may be replaced by halogen atoms.

[0041] In the present invention, when a compound is represented by a structural formula, the symbols (C and H) representing carbon atoms and hydrogen atoms in a hydrocarbon group and / or a hydrocarbon chain may be omitted.

[0042] In the present invention, ppm is the abbreviation of parts per million and is a mass standard.

[0043] In the present invention, the “axial direction” of the electrophotographic photoreceptor refers to the direction in which the rotation axis of the electrophotographic photoreceptor extends, and the “circumferential direction” of the electrophotographic photoreceptor refers to the rotation direction of the electrophotographic photoreceptor.

[0044] <Electrophotographic photoreceptor>

[0045] The electronic photographic photoreceptor of this embodiment (hereinafter also referred to as "photoreceptor") comprises: a conductive substrate; a charge generating layer, which is arranged on the conductive substrate; a charge transport layer, which is arranged on the charge generating layer and contains inorganic oxide particles, and the charge generating layer and the charge transport layer form a photosensitive layer; and an inorganic protective layer, which is arranged on the photosensitive layer.

[0046] Moreover, in the cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies area ratio A>area ratio B.

[0047] The photoreceptor of this embodiment has the above-described structure, which ensures the crack resistance of the inorganic protective layer while improving the light transmittance of the charge transport layer. The reason for this is presumably as follows.

[0048] Conventionally, in electrophotographic photoreceptors having an inorganic protective layer, the following technology is known: to prevent the inorganic protective layer from cracking due to mechanical load, the charge transport layer forming the inorganic protective layer is made to contain inorganic oxide particles (e.g., silica particles), thereby increasing the hardness of the charge transport layer. When the hardness of the charge transport layer is increased, the deformation of the charge transport layer relative to the load is reduced, thereby reducing the deformation of the inorganic protective layer and improving the crack resistance.

[0049] On the other hand, it is generally known that the greater the amount of inorganic oxide particles filled, the higher the hardness of the charge transport layer.

[0050] However, when the loading of inorganic oxide particles is high, the light transmittance of the charge transport layer decreases. When the light transmittance of the charge transport layer decreases, light has difficulty reaching the charge generation layer located below the charge transport layer, reducing the charge generation efficiency of the charge generation layer. As a result, the electrical properties of the photoreceptor are degraded.

[0051] In contrast, in the photosensitive body of the present embodiment, in the cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies the area ratio A>area ratio B.

[0052] As a result, a large number of inorganic oxide particles are present on the surface layer of the charge transport layer in contact with the inorganic protective layer, thereby increasing the hardness of the surface layer. As a result, the crack resistance of the inorganic protective layer can be ensured.

[0053] On the other hand, a relatively small amount of inorganic oxide particles exists in the inner layer of the charge transport layer that is in contact with the charge generation layer, thereby improving the light transmittance of the entire charge transport layer.

[0054] From the above, it is presumed that the photoreceptor of this embodiment improves the light transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer.

[0055] Next, the photoreceptor of this embodiment will be described in detail.

[0056] Figure 1 This is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to this embodiment. Figure 1 The photoreceptor 10A shown has a laminated photosensitive layer. Photoreceptor 10A has a structure in which an undercoat layer 2, a charge generating layer 3, a charge transport layer 4, and an inorganic protective layer 6 are sequentially laminated on a conductive substrate 1. The charge generating layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called functionally separated photosensitive layer). Photoreceptor 10A may also have an intermediate layer (not shown) between the undercoat layer 2 and the charge generating layer 3. The undercoat layer 2 may or may not be present.

[0057] (Area Ratio of Inorganic Oxide Particles Contained in Charge Transport Layer)

[0058] In cross-sectional observation of the charge transport layer, with 1 / 2 of the charge transport layer thickness as the boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies area ratio A>area ratio B.

[0059] Here, the surface layer of the charge transport layer refers to a region from a surface located at 1 / 2 of the film thickness of the charge transport layer to a surface where the charge transport layer is in contact with the inorganic protective layer.

[0060] The inner layer of the charge transport layer refers to a region from a surface located at 1 / 2 of the film thickness of the charge transport layer to a surface where the charge transport layer and the charge generation layer are in contact.

[0061] From the viewpoint of improving the crack resistance of the inorganic protective layer and the transmittance of the charge transport layer, the difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is preferably greater than 1% and less than 75%, more preferably greater than 10% and less than 75%, further preferably greater than 20% and less than 75%, and even more preferably greater than 20% and less than 75%.

[0062] From the viewpoint of improving the crack resistance of the inorganic protective layer and the transmittance of the charge transport layer, the area ratio A of the inorganic oxide particles contained in the surface layer is preferably greater than or equal to 60% and less than or equal to 75%, more preferably greater than or equal to 60% and less than or equal to 72%, and further preferably greater than or equal to 60% and less than or equal to 70%.

[0063] From the viewpoint of improving the crack resistance of the inorganic protective layer and the light transmittance of the charge transport layer, the area ratio B of the inorganic oxide particles contained in the inner layer is preferably less than 60%, more preferably 55% or less, and even more preferably 50% or less.

[0064] In order to ensure that the area ratio A and area ratio B of the inorganic oxide particles satisfy the relationship of area ratio A > area ratio B, there are methods such as controlling the drying conditions of the coating film during formation of the charge transport layer. Specifically, there are methods such as increasing the temperature of the hot air blown onto the coating film, increasing the viscosity of the liquid, and changing the solvent to a solvent with a lower boiling point.

[0065] (Method for observing the cross section of the charge transport layer)

[0066] The cross-sectional observation method of the charge transport layer is as follows.

[0067] The photosensitive layer of the photoreceptor is cut in the thickness direction using a knife or the like, and a sample is obtained with the exposed cut surface serving as an observation surface.

[0068] Next, the observation surface of the sample was observed using a scanning electron microscope (SEM) to obtain a cross-sectional SEM image of the photosensitive layer.

[0069] Then, using a cross-sectional SEM image of the photosensitive layer, the area ratio A of the inorganic oxide particles present in the surface layer and the area ratio B of the inorganic oxide particles present in the inner layer relative to the boundary line located at 1 / 2 of the film thickness of the charge transport layer were determined.

[0070] Specifically, the inorganic oxide particles present in each layer are observed, and the images of the observed inorganic oxide particles are analyzed using image processing and analysis software WinRoof (manufactured by Mitani Shoji Co., Ltd.), and the area ratios of all inorganic oxide particles observed in each layer relative to each layer of the charge transport layer (i.e., area ratios A and B) are calculated respectively.

[0071] (Structure of Inorganic Oxide Particles Contained in Charge Transport Layer)

[0072] Examples of the inorganic oxide particles include silica particles, alumina particles, and titania particles.

[0073] Among them, from the viewpoint of suppressing the reduction in electrical characteristics of the photoreceptor, the inorganic oxide particles are preferably silica particles.

[0074] Examples of the silica particles include dry silica particles and wet silica particles.

[0075] Examples of dry silica particles include combustion silica (fumed silica) obtained by burning a silane compound and explosion silica obtained by explosively burning metallic silicon powder.

[0076] Examples of wet silica particles include wet silica particles obtained by a neutralization reaction of sodium silicate and an inorganic acid (precipitated silica synthesized / aggregated under alkaline conditions, gel-process silica particles synthesized / aggregated under acidic conditions), colloidal silica particles (silica sol particles) obtained by making acidic silicic acid alkaline and polymerizing it, and sol-gel silica particles obtained by hydrolyzing an organic silane compound (e.g., alkoxysilane).

[0077] As the silica particles, from the viewpoint of suppressing image defects caused by deterioration of electrical characteristics, preferably used are fumed silica (fumed silica) having a small number of silanol groups on the surface and a poor void structure.

[0078] The inorganic oxide particles are preferably surface-treated with a hydrophobizing agent from the viewpoint of dispersibility in the charge transport layer-forming coating solution. Examples of the hydrophobizing agent include well-known silane compounds such as chlorosilane, alkoxysilane, and silazane.

[0079] As the hydrophobizing agent, a silane compound having a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group is preferred. That is, the silica particles preferably have a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group on their surface.

[0080] Examples of silane compounds having a trimethylsilyl group include trimethylchlorosilane, trimethylmethoxysilane, and 1,1,1,3,3,3-hexamethyldisilazane. Examples of silane compounds having a decylsilyl group include decyltrichlorosilane, decyldimethylchlorosilane, and decyltrimethoxysilane. Examples of silane compounds having a phenyl group include triphenylmethoxysilane and triphenylchlorosilane.

[0081] From the viewpoint of improving the crack resistance of the inorganic protective layer and the light transmittance of the photoreceptor, the average particle size of the inorganic oxide particles is preferably 20 nm to 200 nm, more preferably 30 nm to 180 nm, and even more preferably 40 nm to 150 nm.

[0082] The average particle size of the inorganic oxide particles can be determined by the following measurement method.

[0083] The inorganic oxide particles are removed from the charge transport layer. Examples of methods for removing the inorganic oxide particles from the charge transport layer include immersing the charge transport layer peeled from the photoreceptor in an organic solvent that dissolves the binder resin, thereby dissolving the binder resin with the organic solvent and removing the inorganic oxide particles; or heating the charge transport layer peeled from the photoreceptor to approximately 800°C to eliminate the binder resin and remove the inorganic oxide particles.

[0084] The inorganic oxide particles were observed using a scanning electron microscope, and the equivalent circle diameters of 100 randomly selected primary particles were determined. The arithmetic average of the equivalent circle diameters was taken as the average particle size.

[0085] From the viewpoint of improving the crack resistance of the inorganic protective layer, the mass ratio of the inorganic oxide particles in the charge transport layer is preferably 60 mass % or more, more preferably 62.5 mass % or more, and even more preferably 65 mass % or more.

[0086] From the viewpoint of light transmittance of the photoreceptor, the mass ratio of the silica particles in the photosensitive layer is preferably 80 mass % or less, more preferably 77.5 mass % or less, and even more preferably 75 mass % or less.

[0087] (Light transmittance of charge transport layer)

[0088] The light transmittance of the charge transport layer is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0089] When the light transmittance of the charge transport layer is within the above range, the electrical characteristics of the photoreceptor are improved.

[0090] The light transmittance of the charge transport layer is measured as follows.

[0091] The charge transport layer was peeled off from the photoreceptor and used as a sample.

[0092] The light transmittance in the thickness direction of the sample was measured from a wavelength of 730 to 830 nm using an ultraviolet-visible spectrophotometer, and the average value of the transmittance per 10 nm was determined and used as the light transmittance.

[0093] (Young's modulus of charge transport layer)

[0094] The Young's modulus of the charge transport layer is preferably 12 GPa or more, more preferably 15 GPa or more, and even more preferably 20 GPa or more.

[0095] When the Young's modulus of the charge transport layer is within the above range, the crack resistance of the inorganic protective layer is improved.

[0096] However, due to the limitation of the filling amount of the inorganic oxide particles, the Young's modulus of the charge transport layer is, for example, 20 GPa or less.

[0097] The Young's modulus of the charge transport layer is obtained by a nanoindentation method, and the measurement method is as follows.

[0098] The inorganic protective layer is removed from the photoreceptor by, for example, peeling the inorganic protective layer with a single-edged knife, and measuring the Young's modulus of the charge transport layer.

[0099] The photoreceptor whose inorganic protective layer is removed and whose outer peripheral surface serves as a charge transport layer is fixed so that the axial direction of the photoreceptor is in the horizontal direction.

[0100] Next, in this state, the Young's modulus of the outer peripheral surface of the charge transport layer was measured using a nanoindenter. Measurements were made at four locations spaced 90° apart in the circumferential direction of the photoreceptor, centered in the axial direction. The Young's modulus values ​​obtained at these four locations were then arithmetic averaged.

[0101] In addition, the measurement conditions of the Young's modulus using a nanoindenter are as follows.

[0102] Test equipment: Trade name HM-500, Fischer Instruments Co., Ltd.

[0103] Indenter: Diamond triangular indenter with 115° angle

[0104] ·Load: 75mN

[0105] Next, each layer of the photoreceptor will be described in detail.

[0106] [Conductive substrate]

[0107] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Furthermore, examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" means a volume resistivity of less than 1×10 13 Ω·cm.

[0108] When using electrophotographic photoreceptors in laser printers, the surface of the conductive substrate is preferably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm to suppress interference fringes generated during laser irradiation. When using non-interfering light as the light source, roughening is not particularly necessary to prevent interference fringes. However, roughening can help extend the life of the printer by suppressing defects caused by irregularities on the conductive substrate surface.

[0109] Examples of methods for roughening the surface include wet honing in which an abrasive is suspended in water and sprayed onto the conductive substrate; centerless grinding in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0110] As a method for roughening the surface, the following method can be cited: instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0111] The roughening treatment based on anodizing is to form an oxide film on the surface of the conductive substrate by carrying out anodizing in an electrolyte solution with a conductive substrate made of metal (such as aluminum) as an anode. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution etc. can be enumerated. However, the porous anodized film formed by anodizing is chemically active under the original state, easily contaminated, and the resistance change caused by the environment is also large. Thus, preferably, the porous anodized film is carried out to a sealing process, in which the micropores of the oxide film are blocked by the volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel can be added), and the oxide film is changed into a more stable hydrated oxide.

[0112] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. If the film thickness is within the above range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0113] The conductive substrate may be subjected to treatment using an acidic treatment liquid or boehmite treatment.

[0114] The treatment using an acidic treatment solution is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. As for the mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution, for example, phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is in the range of 0.5% by mass to 2% by mass, and the overall concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0115] Boehmite treatment can be performed, for example, by immersing the substrate in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the substrate with heated steam at 90°C to 120°C for 5 to 60 minutes. The coating preferably has a thickness of 0.1 μm to 5 μm. Alternatively, the substrate may be further anodized using an electrolyte solution with low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0116] [Base coat]

[0117] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0118] Examples of the inorganic particles include particles having a powder resistance (volume resistivity) of 1×10 2 Ω·cm or more and 1×10 11 Inorganic particles with a particle size of Ω·cm or less.

[0119] Among them, as the inorganic particles having the above-mentioned resistance value, for example, metal oxide particles such as tin oxide particles, titanium dioxide particles, zinc oxide particles, and zirconium oxide particles are preferred, and zinc oxide particles are particularly preferred.

[0120] The specific surface area of ​​the inorganic particles by the BET method is preferably, for example, 10 m 2 / g or above.

[0121] The volume average particle size of the inorganic particles is preferably, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

[0122] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

[0123] The inorganic particles may be surface-treated. Inorganic particles having different surface treatments or two or more inorganic particles having different particle sizes may be mixed and used.

[0124] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

[0125] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0126] Silane coupling agents can also be used in combination of two or more. For example, a silane coupling agent having an amino group and other silane coupling agents can also be used in combination. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, etc. can be mentioned, but it is not limited thereto.

[0127] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0128] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0129] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier blocking properties, the undercoat layer preferably contains an electron acceptor compound (acceptor compound) together with the inorganic particles.

[0130] Examples of electron acceptor compounds include quinone compounds such as tetrachlorobenzoquinone and tetrabromobenzoquinone; tetracyanoquinolinemethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone; and electron transporting substances such as benzophenone compounds.

[0131] As the electron acceptor compound, a compound having an anthraquinone structure is particularly preferred. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, etc. are preferred.

[0132] Specifically, for example, anthraquinone, alizarin, quinizarin, anthrarutin, purpurin, etc. are preferable.

[0133] The electron acceptor compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surface of the inorganic particles.

[0134] Examples of a method for attaching the electron acceptor compound to the surface of the inorganic particles include a dry method and a wet method.

[0135] The dry method, for example, involves adding an electron acceptor compound directly or dissolved in an organic solvent while stirring the inorganic particles using a mixer with high shear force, spraying the electron acceptor compound with dry air or nitrogen to adhere the electron acceptor compound to the surface of the inorganic particles. The dropwise addition or spraying of the electron acceptor compound is preferably performed at a temperature below the boiling point of the solvent. Alternatively, the dropwise addition or spraying of the electron acceptor compound may be followed by sintering at a temperature above 100°C. The sintering process is not particularly limited, as long as the temperature and time required to achieve electrophotographic properties are sufficient.

[0136] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent using a stirrer, ultrasonic disperser, sand mill, grinder, ball mill, etc., while adding an electron acceptor compound and stirring or dispersing, and then removing the solvent to attach the electron acceptor compound to the surface of the inorganic particles. The solvent removal method is, for example, distillation removal by filtration or distillation. After the solvent is removed, sintering may be further performed at a temperature above 100°C. There are no particular restrictions on sintering, as long as the temperature and time are such that electronic photographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may also be removed before adding the electron acceptor compound. Examples thereof include a method of removing the water content in the solvent while stirring and heating, and a method of removing the water content by azeotropic reaction with the solvent.

[0137] The electron acceptor compound may be attached before or after the inorganic particles are subjected to surface treatment using a surface treatment agent, or may be attached simultaneously with the surface treatment using a surface treatment agent.

[0138] The content of the electron acceptor compound is, for example, preferably 0.01% by mass or more and 20% by mass or less, and more preferably 0.01% by mass or more and 10% by mass or less, relative to the inorganic particles.

[0139] Examples of the binder resin used for the primer layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, urea-formaldehyde resins, phenol resins, phenol-formaldehyde resins, melamine resins, polyurethane resins, alkyd resins, epoxy resins, and other known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; alkoxytitanium compounds; organic titanium compounds; and silane coupling agents.

[0140] Examples of the binder resin used for the primer layer include charge transporting resins having a charge transporting group and conductive resins (eg, polyaniline).

[0141] Among them, the binder resin used as the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and is particularly preferably a thermosetting resin such as urea-formaldehyde resin, phenol resin, phenol-formaldehyde resin, melamine resin, polyurethane resin, unsaturated polyester resin, alkyd resin, epoxy resin; or a resin obtained by reacting at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin with a curing agent.

[0142] When two or more of these binder resins are used in combination, the mixing ratio thereof is set as needed.

[0143] The undercoat layer may contain various additives for the purpose of improving electrical characteristics, enhancing environmental stability, and improving image quality.

[0144] Examples of additives include known materials such as polycyclic condensation-based and azo-based electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, alkoxytitanium compounds, organic titanium compounds, and silane coupling agents. Silane coupling agents are used for surface treatment of inorganic particles as described above, but can also be added to the primer as an additive.

[0145] Examples of the silane coupling agent used as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0146] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octylate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0147] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octyl glycolate, titanium ammonium lactate, titanium lactate, titanium ethyl lactate, triethanolamine titanium, and polyhydroxytitanium stearate.

[0148] Examples of the aluminum chelate compound include aluminum isopropoxide, diisopropoxymonobutoxyaluminum, aluminum butyrate, diethylacetoacetate aluminum diisopropoxide, and tris(ethylacetoacetoxy)aluminum.

[0149] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0150] The Vickers hardness of the primer layer is preferably 35 or higher.

[0151] To suppress moire patterns, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to be from 1 / (4n) to 1 / 2 of the wavelength λ of the exposure laser used (n is the refractive index of the upper layer).

[0152] To adjust the surface roughness, resin particles or the like may be added to the primer layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the primer layer surface may be ground. Examples of polishing methods include soft leather polishing, sandblasting, wet honing, and grinding.

[0153] The formation of the undercoat layer is not particularly limited and can be performed using a known formation method, for example, by forming a coating film of an undercoat layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0154] Examples of the solvent used for preparing the coating liquid for forming the undercoat layer include well-known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0155] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene dichloride, chloroform, chlorobenzene, and toluene.

[0156] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint sieve.

[0157] Examples of a method for applying the undercoat layer-forming coating liquid to the conductive substrate include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, knife coating, and curtain coating.

[0158] The thickness of the primer layer is preferably set to 15 μm or more, and more preferably set to be within the range of 20 μm or more and 50 μm or less.

[0159] [Middle layer]

[0160] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, phenol-formaldehyde resins, and melamine resins.

[0161] The intermediate layer may also be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0162] The compounds used in the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0163] Among them, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0164] The intermediate layer can be formed without particular limitation and can be formed using a known formation method, for example, by forming a coating film of an intermediate layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0165] As a coating method for forming the intermediate layer, a common method such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, curtain coating, etc. is used.

[0166] The thickness of the intermediate layer is preferably set within a range of 0.1 μm to 3 μm. The intermediate layer can also be used as a primer layer.

[0167] [Charge Generation Layer]

[0168] The charge generating layer is, for example, a layer comprising a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. This vapor-deposited layer of charge generating material is suitable for use with non-interfering light sources such as LEDs (Light Emitting Diodes) and organic EL (Electro-Luminescence) image arrays.

[0169] Examples of the charge generating material include azo pigments such as disazo and trisazo; ring-condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0170] Among them, in order to cope with near-infrared laser exposure, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials. Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine are more preferred.

[0171] On the other hand, in order to cope with near-ultraviolet laser exposure, preferred charge generating materials include cyclic aromatic pigments such as dibromoanthrone and anthrone, thioindigo pigments, tetraazaporphyrin compounds, zinc oxide, trigonal selenium, and disazo pigments.

[0172] The above-mentioned charge generation material can also be used when using a non-interfering light source such as an LED or an organic EL array whose central wavelength of light emission is from 450 nm to 780 nm.

[0173] When using n-type semiconductors such as cyclic aromatic pigments, perylene pigments, and azo pigments as charge-generating materials, dark current generation is less likely to occur, and image defects known as black spots can be suppressed even in thin films. The n-type is determined by the polarity of the photocurrent flowing using the commonly used time-of-flight method, with those that more readily carry electrons as carriers than holes being designated n-type.

[0174] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0175] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. Here, "insulating property" means a volume resistivity of 10 13 These binder resins are used alone or in combination of two or more.

[0176] The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10:1 to 1:10 in terms of mass ratio.

[0177] The charge generating layer may contain other known additives.

[0178] The charge generating layer can be formed without particular limitation and can be formed using a known method, for example, by forming a film of a charge generating layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the film, and optionally heating it. The charge generating layer can also be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when using cyclic aromatic pigments or perylene pigments as the charge generating material.

[0179] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene dichloride, chloroform, chlorobenzene, and toluene. These solvents may be used alone or in combination of two or more.

[0180] As a method for dispersing particles (e.g., charge generating material) in a coating liquid for forming a charge generating layer, for example, a medium disperser such as a ball mill, a vibrating ball mill, a grinder, a sand mill, a horizontal sand mill, or a medium-free disperser such as a stirrer, an ultrasonic disperser, a roller mill, or a high-pressure homogenizer is used. As a high-pressure homogenizer, for example, a collision method in which the dispersion liquid is subjected to liquid-liquid collision or liquid-wall collision under high pressure, or a penetration method in which the dispersion liquid is dispersed by penetrating a fine flow path under high pressure can be cited. During dispersion, it is effective to set the average particle size of the charge generating material in the coating liquid for forming a charge generating layer to be less than 0.5 μm, preferably less than 0.3 μm, and more preferably less than 0.15 μm.

[0181] Examples of methods for applying the charge generating layer-forming coating liquid to the undercoat layer (or intermediate layer) include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0182] The thickness of the charge generating layer is preferably set to be in the range of 0.1 μm to 5.0 μm, and more preferably in the range of 0.2 μm to 2.0 μm.

[0183] [Charge transport layer]

[0184] The charge transport layer is, for example, a layer containing a binder resin, a charge transport material, and inorganic oxide particles. The charge transport layer may also be a layer containing a polymer charge transport material.

[0185] Examples of charge transport materials include electron transport compounds such as quinone compounds such as p-benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, and anthraquinone; tetracyanoquinolmethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanoethylene compounds; and vinyl compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

[0186] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferred.

[0187]

[0188] In the structural formula (a-1), Ar T1 、Ar T2 , and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 、R T5 、R T6 、R T7 , and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0189] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0190]

[0191] In the structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 、R T102 、R T111 and R T112Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ), R T12 、R T13 、R T14 、R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0192] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0193] From the viewpoint of charge mobility, the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2) are particularly preferably the one having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0194] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials are particularly preferred. The polymer charge transport material can be used alone or in combination with a binder resin.

[0195] The binder resin used in the charge transport layer can include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin (styrene-alkyd resin), poly-N-vinyl carbazole, polysilane, etc. Among them, as the binder resin, preferably polycarbonate resin or polyarylate resin. These binder resins are used alone or in combination.

[0196] The mixing ratio of the charge transport material and the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0197] The charge transport layer may contain other known additives.

[0198] The charge transport layer is formed by coating. Examples of coating methods include dissolving or dispersing a binder resin, a charge transport material, and inorganic oxide particles in a solvent to prepare a charge transport layer-forming coating solution, applying the charge transport layer-forming coating solution to the surface of the charge generating layer to form a coating film, and drying the coating film.

[0199] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanol; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and ethylene chloride; and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents can be used alone or in combination of two or more.

[0200] As a method for dispersing the inorganic oxide particles in the charge transport layer-forming coating liquid, for example, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, or a horizontal sand mill; or a media-free disperser such as a stirrer, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer is used.

[0201] Examples of the coating method for applying the charge transport layer-forming coating liquid onto the charge generating layer include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0202] The thickness of the charge transport layer is preferably set to, for example, 5 μm or more and 50 μm or less, and more preferably set to be within the range of 10 μm or more and 30 μm or less.

[0203] [Inorganic protective layer]

[0204] The inorganic protective layer is an inorganic material layer. Examples of the inorganic material include metal oxides such as gallium oxide, aluminum oxide, zinc oxide, titanium dioxide, indium oxide, tin oxide, and boron oxide; metal nitrides such as gallium nitride, aluminum nitride, zinc nitride, titanium nitride, indium nitride, tin nitride, and boron nitride; carbon-based and silicon-based inorganic materials such as diamond-like carbon, amorphous carbon, amorphous hydrogenated carbon, hydrogen / fluorinated amorphous carbon, amorphous silicon carbide, amorphous hydrogenated silicon carbide, amorphous silicon, and amorphous hydrogenated silicon; and mixed crystals thereof.

[0205] From the viewpoint of abrasion resistance and electrical properties of the photoreceptor, the inorganic protective layer is preferably a layer containing a metal oxide, more preferably a layer containing gallium oxide. The metal oxide contained in the inorganic protective layer may be one kind or two or more kinds.

[0206] From the viewpoint of maintaining the electrostatic latent image, the volume resistivity of the inorganic protective layer is preferably 1.0×10 10 Ω·cm or more, more preferably 1.0×10 11 Ω·cm or more.

[0207] The method for measuring the volume resistivity of the inorganic protective layer is as follows.

[0208] The inorganic protective layer was peeled off from the photoreceptor and used as a sample. The sample was clamped on the sample holder of an impedance analyzer (TOYO Corporation) and the resistance was measured at an AC voltage of 1 V and a frequency of 100 Hz. The resistance was calculated based on the electrode area and the sample thickness.

[0209] Examples of methods for forming the inorganic protective layer include known vapor phase film formation methods such as plasma CVD (Chemical Vapor Deposition), metal organic vapor phase growth, molecular beam epitaxy, evaporation, and sputtering. For example, the inorganic protective layer can be formed using the plasma CVD film formation apparatus and film formation conditions described in Japanese Patent Application Laid-Open No. 2014-191179.

[0210] From the viewpoint of abrasion resistance and electrical properties of the photoreceptor, the thickness of the inorganic protective layer is preferably 0.2 μm to 10 μm, more preferably 0.4 μm to 8 μm, and even more preferably 0.6 μm to 6 μm.

[0211] The thickness of each layer of the photoreceptor was the arithmetic average of values ​​measured using an electromagnetic film thickness meter. The measurement locations were four locations at 90° intervals in the circumferential direction at the center of the axial direction of the photoreceptor.

[0212] <Image forming apparatus, process cartridge>

[0213] The image forming apparatus of this embodiment includes an electrophotographic photoreceptor, a charging device for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor of this embodiment is employed as the electrophotographic photoreceptor.

[0214] The image forming device of this embodiment applies the following well-known image forming devices: a device equipped with a fixing device for fixing the colorant image transferred to the surface of a recording medium; a device of a direct transfer method for directly transferring the colorant image formed on the surface of an electronic photographic photosensitive body to a recording medium; a device of an intermediate transfer method for transferring the colorant image formed on the surface of an electronic photographic photosensitive body to the surface of an intermediate transfer body for the first time, and transferring the colorant image transferred to the surface of the intermediate transfer body to the surface of a recording medium for the second time; a device equipped with a cleaning device for cleaning the surface of an electronic photographic photosensitive body after the transfer of the colorant image and before charging; a device equipped with an electrostatic elimination device for irradiating the surface of an electronic photographic photosensitive body with electrostatic elimination light for electrostatic elimination after the transfer of the colorant image and before charging; a device equipped with an electronic photographic photosensitive body heating component for increasing the temperature of the electronic photographic photosensitive body and reducing the relative temperature, etc.

[0215] In the case of an intermediate transfer method device, the transfer device, for example, has the following structure: an intermediate transfer body for transferring a colorant image on a surface, a primary transfer device for transferring the colorant image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time, and a secondary transfer device for secondary transferring the colorant image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0216] The image forming apparatus of the present embodiment may be any of a dry development system image forming apparatus and a wet development system (development system using a liquid developer) image forming apparatus.

[0217] In the image forming apparatus of this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a toner cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor of this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may also comprise, for example, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0218] Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and descriptions of the other parts will be omitted.

[0219] Figure 2 This is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0220] like Figure 2 As shown, the image forming apparatus 100 of this embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is positioned so as to expose the electrophotographic photoreceptor 7 through the opening of the process cartridge 300. The transfer device 40 is positioned so as to face the electrophotographic photoreceptor 7 across the intermediate transfer member 50, with a portion of the intermediate transfer member 50 in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 further includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 onto a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) constitute an example of a transfer device.

[0221] Figure 2 The process cartridge 300 in the embodiment of the present invention integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging device), the developing device 11 (an example of a developing device), and the cleaning device 13 (an example of a cleaning device) within a housing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, which is arranged to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0222] exist Figure 2 2 shows an example in which a fibrous member 132 (roller-shaped) for supplying the lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush-shaped) for assisting cleaning are provided as the cleaning device, but these can be arranged as needed.

[0223] Next, each component of the image forming apparatus according to this embodiment will be described.

[0224] - Charging device -

[0225] As the charging device 8, for example, a contact charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. can be used. Alternatively, a non-contact roller charger, a scorotron charger using corona discharge, a corotron charger, or other known chargers can be used.

[0226] -Exposure device-

[0227] As the exposure device 9, for example, there can be cited an optical system device that exposes light such as semiconductor laser, LED light, liquid crystal shutter light to the surface of the electrophotographic photoreceptor 7 in a determined image shape. The wavelength of the light source is set within the spectral sensitivity area of ​​the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared with an oscillation wavelength around 780nm is the mainstream. However, it is not limited to this wavelength, and a laser with an oscillation wavelength of more than 600nm and less than 700nm, or a laser with an oscillation wavelength of more than 400nm and less than 450nm can also be used as a blue laser. In addition, a surface-emitting laser source that can output multiple beams in order to form a color image is also effective.

[0228] -Developing device-

[0229] Examples of the developing device 11 include general developing devices that develop the electrophotographic photoreceptor 7 with or without contacting the developer. The developing device 11 is not particularly limited as long as it has the functions described above, and can be selected based on the intended purpose. Examples include known developing devices that utilize a brush, roller, or the like to deposit a single-component developer or a two-component developer onto the electrophotographic photoreceptor 7. Among these, a developing roller that retains the developer on its surface is preferably used.

[0230] The developer used in the developing device 11 may be a single-component developer containing only toner or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. These developers are known developers.

[0231] - Cleaning device -

[0232] The cleaning device 13 uses a cleaning blade type including a cleaning blade 131. In addition to the cleaning blade type, a brush cleaning type or a simultaneous development cleaning type may be used.

[0233] - Transfer device -

[0234] Examples of the transfer device 40 include known transfer chargers such as a contact transfer charger using a belt, a roller, a film, or a rubber blade, and a scorotron transfer charger or corotron transfer charger utilizing corona discharge.

[0235] -Intermediate transfer body-

[0236] As the intermediate transfer member 50, a belt-shaped intermediate transfer member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity is used. In addition, as the form of the intermediate transfer member, a drum-shaped intermediate transfer member can also be used in addition to the belt-shaped intermediate transfer member.

[0237] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0238] Figure 3 The illustrated image forming apparatus 120 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In image forming apparatus 120, four process cartridges 300 are arranged side by side on an intermediate transfer body 50, with one electrophotographic photoreceptor used for each color. Aside from its tandem configuration, image forming apparatus 120 has the same structure as image forming apparatus 100.

[0239] [Example]

[0240] Hereinafter, embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples.

[0241] In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0242] In the following description, unless otherwise specified, synthesis, production, handling, measurement, etc. were performed at room temperature (25°C ± 3°C).

[0243] <Example 1>

[0244] [Formation of Primer Layer]

[0245] As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm was prepared.

[0246] 100 parts of zinc oxide (average particle size 70 nm, specific surface area 15 m 2 / g, Tayca Co., Ltd.) and 500 parts of toluene were stirred and mixed, and 1.3 parts of a silane coupling agent (trade name: KBM603, Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added and stirred for 2 hours. Subsequently, the toluene was distilled off under reduced pressure, and the mixture was calcined at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0247] 110 parts of surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring at 50°C for 5 hours. The solid content was then filtered and separated by vacuum filtration and dried at 60°C under reduced pressure to obtain zinc oxide with alizarin added thereto.

[0248] 60 parts of alizarin-imparted zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, trade name: Sumidur 3175, Sumitomo Bayer Urethanes Co., Ltd.), and 15 parts of a butyral resin (trade name: S-LEC BM-1, Sekisui Chemical Co., Ltd.) were dissolved in 100 parts of a solution of 68 parts of methyl ethyl ketone and mixed with 5 parts of methyl ethyl ketone. The mixture was dispersed for 2 hours using a sand mill with 1 mm diameter glass beads to obtain a dispersion. 0.005 parts of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: TOSPEARL 145, Momentive Performance Materials) were added to the dispersion as catalysts to obtain a coating solution for forming a primer layer. The primer layer coating solution was applied to the outer peripheral surface of the conductive substrate by dip coating and dried and cured at 170°C for 40 minutes to form a 20 μm thick primer layer.

[0249] [Formation of Charge Generation Layer]

[0250] A mixture of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generating material, 10 parts of a vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Unicar Co., Ltd., Japan) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using glass beads having a diameter of 1 mm for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion, and the mixture was stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature to form a charge generating layer having a thickness of 0.25 μm.

[0251] [Formation of Charge Transport Layer]

[0252] Binder resin: polycarbonate resin (1) (viscosity average molecular weight 40,000, the numerical values ​​in the structural formula represent molar ratio (mol %)) ··· 20 parts

[0253] Charge transport material: CTM-1···15 parts

[0254] Silica particles treated with 1,1,1,3,3,3-hexamethyldisilazane (average particle size 40 nm) ···65 parts

[0255] Solvent: Tetrahydrofuran (THF) 600 parts

[0256] The above materials were stirred and mixed for 12 hours to obtain a charge transport layer coating solution. This charge transport layer coating solution was then dip-coated onto the charge generating layer. Hot air at 135°C was then blown onto the coating film to dry it, forming a charge transport layer with a thickness of 30 μm.

[0257]

[0258] [Formation of Inorganic Protective Layer]

[0259] An amorphous layer containing gallium oxide was formed as an inorganic protective layer by plasma CVD using trimethylgallium as a film-forming material. The layer thickness was set to 1 μm.

[0260] Through the above steps, a photoreceptor is obtained.

[0261] <Examples 2 to 17, Comparative Examples 1 and 2>

[0262] A photoreceptor was obtained in the same manner as in Example 1, except that the average particle size and amount of silica particles during charge transport layer formation were changed according to Table 1, and the drying temperature of the coating was adjusted to achieve the area ratio shown in Table 1. However, in Examples 15 and 16, the film-forming material for forming the inorganic protective layer was changed to dimethylzinc or trimethylaluminum.

[0263] <Photoreceptor Characteristics Measurement>

[0264] The following characteristics of the photoreceptor of each example were measured according to the above-mentioned methods.

[0265] The area ratio A of the silica particles contained in the surface layer and the area ratio B of the silica particles contained in the inner layer, obtained by observing the cross section of the charge transport layer, with half the film thickness of the charge transport layer as the boundary

[0266] ·Light transmittance of the charge transport layer

[0267] Young's modulus of the charge transport layer

[0268] <Photoreceptor Performance Evaluation>

[0269] [Crack resistance of inorganic protective layer]

[0270] The load of cracks in the inorganic protective layer was measured as follows to evaluate the crack resistance of the inorganic protective layer.

[0271] The hardness test using a microhardness tester was repeated while increasing the load by 5 mN from 0 mN. Each time a load was applied, observation was performed using an optical microscope, and the load at which damage occurred in the inorganic protective layer was defined as the crack initiation load. The measurement conditions are as follows. The measurement results are shown in Table 1.

[0272] Test device: Trade name DUH-201, Shimadzu Corporation

[0273] Indenter: Diamond ball indenter

[0274] [Table 1]

[0275]

[0276] The abbreviations described in Table 1 refer to the following compounds.

[0277] GaO: Gallium oxide

[0278] ZnO: zinc oxide

[0279] AlO: aluminum oxide

[0280] The above results show that the photoreceptor of this example improves the light transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the photoreceptor of the comparative example, thereby obtaining an image with excellent image quality.

[0281] (Note) (((1)))

[0283] An electrophotographic photoreceptor, wherein:

[0284] have:

[0285] Conductive substrate;

[0286] a charge generating layer, the charge generating layer being disposed on the conductive substrate;

[0287] a charge transport layer provided on the charge generation layer and comprising inorganic oxide particles, the charge generation layer and the charge transport layer forming a photosensitive layer; and

[0288] an inorganic protective layer, the inorganic protective layer being disposed on the photosensitive layer,

[0289] In cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies area ratio A>area ratio B. (((2)))

[0291] The electrophotographic photoreceptor according to (((1))), wherein

[0292] The difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is 1% or more and 75% or less. (((3)))

[0294] The electrophotographic photoreceptor according to (((2))), wherein

[0295] The difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is 20% or more and 75% or less. (((4)))

[0297] The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein

[0298] The area ratio A of the inorganic oxide particles contained in the surface layer is 60% or more and 75% or less,

[0299] The area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%. (((5)))

[0301] The electrophotographic photoreceptor according to (((4))), wherein

[0302] The area ratio A of the inorganic oxide particles contained in the surface layer is 60% or more and 70% or less,

[0303] The area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%. (((6)))

[0305] The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein

[0306] The charge transport layer has a light transmittance of 80% or more. (((7)))

[0308] The electrophotographic photoreceptor according to any one of (((1))) to (((6))), wherein

[0309] The charge transport layer has a Young's modulus of 12 GPa or more. (((8)))

[0311] The electrophotographic photoreceptor according to any one of (((1))) to (((7))), wherein

[0312] The inorganic oxide particles are silica particles. (((9)))

[0314] The electrophotographic photoreceptor according to any one of (((1))) to (((8))), wherein

[0315] The inorganic protective layer is a layer containing a metal oxide. (((10)))

[0317] The electrophotographic photoreceptor according to any one of (((1))) to (((9))), wherein

[0318] The inorganic protective layer is a layer containing gallium oxide. (((11)))

[0320] A processing box, wherein

[0321] An electrophotographic photoreceptor according to any one of (((1))) to (((10))),

[0322] The process cartridge is attachable to and detachable from the image forming apparatus. (((12)))

[0324] An image forming apparatus comprising:

[0325] The electrophotographic photoreceptor according to any one of (((1))) to (((10)));

[0326] a charging device for charging the surface of the electrophotographic photoreceptor;

[0327] an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0328] a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and

[0329] A transfer device transfers the toner image to a surface of a recording medium.

[0330] According to (((1))), an electronic photographic photosensitive body is provided, which comprises: a conductive substrate; a charge generating layer, the charge generating layer being arranged on the conductive substrate; a charge transport layer, the charge transport layer being arranged on the charge generating layer and comprising inorganic oxide particles; and an inorganic protective layer, the charge generating layer and the charge transport layer forming a photosensitive layer, the charge generating layer and the charge transport layer being arranged on the photosensitive layer, while ensuring the crack resistance of the inorganic protective layer, the transmittance of the charge transport layer is improved compared with the following situation: in cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same.

[0331] According to (((2))), an electronic photographic photoreceptor is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is less than 1% or exceeds 75%.

[0332] According to (((3))), an electronic photographic photoreceptor is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is less than 20% or exceeds 75%.

[0333] According to (((4))), an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer is less than 60% or exceeds 75%, or the case where the area ratio B of the inorganic oxide particles contained in the inner layer is greater than 60%.

[0334] According to (((5))), an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer is less than 60% or exceeds 70%, or the case where the area ratio B of the inorganic oxide particles contained in the inner layer exceeds 60%.

[0335] According to (((6))), an electrophotographic photoreceptor is provided in which the light transmittance of the charge transport layer is improved while ensuring the crack resistance of the inorganic protective layer, compared with a case where the light transmittance of the charge transport layer is less than 80%.

[0336] According to (((7))), an electrophotographic photoreceptor is provided in which the light transmittance of the charge transport layer is improved while ensuring the crack resistance of the inorganic protective layer, compared with a case where the Young's modulus of the charge transport layer is less than 12 GPa.

[0337] According to (((8))), an electronic photographic photosensitive body is provided, which contains silica particles in the charge transport layer, thereby improving the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0338] According to (((9))), an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer containing metal oxide, compared with the case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0339] According to (((10))), an electronic photographic photosensitive body is provided, which improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer containing gallium oxide, compared with a case where the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

[0340] According to (((11))), or (((12))), a processing box or an image forming device having an electronic photographic photosensitive body is provided, wherein the electronic photographic photosensitive body comprises: a conductive substrate; a charge generating layer, the charge generating layer being arranged on the conductive substrate; a charge transport layer, the charge transport layer being arranged on the charge generating layer and comprising inorganic oxide particles, the charge generating layer and the charge transport layer forming a photosensitive layer; and an inorganic protective layer, the inorganic protective layer being arranged on the photosensitive layer, the processing box or the image forming device improves the transmittance of the charge transport layer while ensuring the crack resistance of the inorganic protective layer, compared with the following situation: in the applied electronic photographic photosensitive body, in the cross-sectional observation of the charge transport layer, the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer are the same, with 1 / 2 of the film thickness of the charge transport layer as the boundary.

Claims

1. An electrophotographic photoreceptor, characterized in that have: Conductive substrate; a charge generating layer, the charge generating layer being disposed on the conductive substrate; a charge transport layer, the charge transport layer being provided on the charge generation layer and comprising inorganic oxide particles, the charge generation layer and the charge transport layer forming a photosensitive layer; as well as an inorganic protective layer, the inorganic protective layer being disposed on the photosensitive layer, In cross-sectional observation of the charge transport layer, with 1 / 2 of the film thickness of the charge transport layer as the boundary, the relationship between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer satisfies area ratio A>area ratio B.

2. The electrophotographic photoreceptor according to claim 1, wherein The difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is 1% or more and 75% or less.

3. The electrophotographic photoreceptor according to claim 2, wherein The difference between the area ratio A of the inorganic oxide particles contained in the surface layer and the area ratio B of the inorganic oxide particles contained in the inner layer is 20% or more and 75% or less.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein The area ratio A of the inorganic oxide particles contained in the surface layer is 60% or more and 75% or less, The area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%.

5. The electrophotographic photoreceptor according to claim 4, wherein The area ratio A of the inorganic oxide particles contained in the surface layer is 60% or more and 70% or less, The area ratio B of the inorganic oxide particles contained in the inner layer is less than 60%.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The charge transport layer has a light transmittance of 80% or more.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein The charge transport layer has a Young's modulus of 12 GPa or more.

8. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein The inorganic oxide particles are silicon dioxide particles.

9. The electrophotographic photoreceptor according to any one of claims 1 to 8, wherein The inorganic protective layer is a layer containing a metal oxide.

10. The electrophotographic photoreceptor according to any one of claims 1 to 9, wherein The inorganic protective layer is a layer containing gallium oxide.

11. A process cartridge, characterized in that: An electrophotographic photoreceptor according to any one of claims 1 to 10, The process cartridge is attachable to and detachable from the image forming apparatus.

12. An image forming apparatus, characterized in that: have: The electrophotographic photoreceptor according to any one of claims 1 to 10; a charging device for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; as well as A transfer device transfers the toner image to a surface of a recording medium.

Images