Electrophotographic photoreceptor, electrophotographic apparatus having the electrophotographic photoreceptor, and process cartridge

Abstract

To provide an electrophotographic photoreceptor with which the occurrence of a ghost is suppressed even when used in an electrophotographic device not having neutralization means, and which has a curable hole transport layer.SOLUTION: Provided is an electrophotographic photoreceptor comprising a support medium, a charge generation layer, a first hole transport layer, and a second hole transport layer, wherein the second hole transport layer contains a hole transportable compound (mass W1, energy value of highest occupied molecular orbital, CTM1HOMO) expressed by formula (1), a hole transportable compound (mass W2) expressed by formula (2) and / or a hole transportable compound (mass W3)(energy value of highest occupied molecular orbital, CTM2HOMO) repressed by formula (3), the value calculated by formula (I) is 0.05 mass% to 5.0 mass% and satisfies formula (II). Formula (I): (W2+W3) / (W1+W2+W3)×100 (mass%), formula (II): 0.05(eV)≤|CTM2HOMO|-|CTM1HOMO|≤0.30(eV).SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] The surface layer of an electrophotographic photoreceptor is required to have durability and stability because it is repeatedly subjected to stresses caused by a series of electrophotographic processes, including charging, exposure, development, transfer, and cleaning. One method for improving durability is to incorporate a curable resin into the surface layer of the electrophotographic photoreceptor. However, providing a highly durable surface layer presents a problem in that the potential difference between the exposed and unexposed areas during the previous image output affects the next image output, exacerbating the so-called ghost phenomenon, which appears as a difference in image density. This problem is usually addressed by providing a static elimination process, in which light irradiation or the like is performed after each cycle of the electrophotographic process is completed.

[0003] On the other hand, in recent years, there has been a strong demand for simplification and cost reduction of electrophotographic device processes, and there is a demand for designs that can omit existing modules, etc. For this reason, there is a demand for electrophotographic photoreceptors that can suppress ghost images without providing a static elimination process. Patent Document 1 describes that the ghost phenomenon is suppressed by devising the material composition of the surface layer of an electrophotographic photosensitive member. However, this composition is not for a highly durable electrophotographic photosensitive member in which the surface layer contains a curable resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-101136 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for not only high durability of electrophotographic photosensitive members but also technology that can suppress image defects even in simplified processes. An object of the present invention is to provide an electrophotographic photosensitive member which has a ghost phenomenon suppressing effect even in a highly durable electrophotographic photosensitive member and which has good electrical properties, and an electrophotographic apparatus and a process cartridge which have the electrophotographic photosensitive member. [Means for solving the problem]

[0006] That is, according to one aspect of the present invention, An electrophotographic photoreceptor having a support, a charge generating layer on the support, a first hole transport layer on the charge generating layer, and a second hole transport layer on the first hole transport layer, wherein the second hole transport layer is a surface layer, the second hole transport layer a hole transporting compound represented by the following formula (1); at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3); The composition contains a copolymer of The mass of the hole transport compound represented by the following formula (1) contained in the composition is represented by W1: The mass of the hole transport compound represented by the following formula (2) contained in the composition is represented by W2: When the mass of the hole transport compound represented by the following formula (3) contained in the composition is defined as W3, the value calculated by the following formula (I) is 0.05 mass % to 5.0 mass %, (W2+W3) / (W1+W2+W3)×100(mass%)...Formula (I) and, The energy value of the highest occupied molecular orbital of the hole transport compound represented by the following formula (1), obtained as a result of energy calculation by the density functional method B3LYP / 6-31G* after structural optimization of the hole transport compound, is defined as CTM1HOMO, When the energy value of the highest occupied molecular orbital of at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3), obtained as a result of energy calculation by the density functional method B3LYP / 6-31G* after structural optimization of the hole transport compound, is defined as CTM2HOMO: The CTM1HOMO and the CTM2HOMO satisfy the following formula (II): An electrophotographic photoreceptor is provided. 0.05(eV)≦|CTM2HOMO|-|CTM1HOMO|≦0.30(eV) ···(II)

[0007] [ka]

[0008] (In formula (1), R 11 and R 12 R each independently represents an alkylene group having 2 to 6 carbon atoms. 13 and R 14 Each of n independently represents a hydrogen atom or a methyl group. 1 teeth, 1 R 15 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 11 is an integer between 0 and 5. 11 If x is an integer between 2 and 5, 11 R 15 may be the same or different. 16 represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 12 is an integer between 0 and 4. 12 If x is an integer between 2 and 4, 12 R 16 may be the same or different.)

[0009] [ka]

[0010] (In formula (2), R 21 and R 22 R each independently represents an alkylene group having 2 to 6 carbon atoms. 23 and R 24 Each of n independently represents a hydrogen atom or a methyl group. 2 teeth, 1 R 25 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 21 is an integer between 0 and 5. 21 If x is an integer between 2 and 5, 21 R 25 may be the same or different. 26 represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 22 is an integer between 0 and 4. 22 If x is an integer between 2 and 4, 22 R 26 may be the same or different.)

[0011] [ka]

[0012] (In formula (3), R 31 and R 32 R each independently represents an alkylene group having 2 to 6 carbon atoms. 33 and R 34 Each of n independently represents a hydrogen atom or a methyl group. 3 teeth, 1 R 35 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 31 is an integer between 0 and 5. 31 If x is an integer between 2 and 5, 31 R 35 may be the same or different. 36represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 32 is an integer between 0 and 4. 32 If x is an integer between 2 and 4, 32 R 36 may be the same or different.) [Effects of the Invention]

[0013] As described above, according to the present invention, it is possible to provide an electrophotographic photosensitive member, an electrophotographic apparatus, and a process cartridge having an electrophotographic photosensitive member, which have a ghost phenomenon suppressing effect, good durability, and excellent electrical properties. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic view illustrating an example of a process cartridge having an electrophotographic photosensitive member. [Figure 2] 1 is a schematic diagram illustrating an example of an electrophotographic apparatus having an electrophotographic photosensitive member. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of an apparatus for pressure-contact shape transfer processing of the surface of an electrophotographic photosensitive member. [Figure 4] FIG. 1 is a schematic diagram showing an example of a stamper mold used for pressure bonding. [Figure 5] FIG. 10 is a diagram showing an image for evaluating the ghost phenomenon used in the examples. [Figure 6] FIG. 6 is a diagram showing a "halftone image of a one-dot knight pattern" in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0015] Below, we will explain the form for implementing the present invention with reference to the drawings, but the scope of the present disclosure is not limited to this form alone, and modifications that do not detract from the intent of the present disclosure are also included in the present invention. The present invention is applicable to electrophotographic photoreceptors in which the surface layer contains a hole transport compound having a chain-polymerizable functional group. To improve the durability of electrophotographic photoreceptors, it is required to use a surface layer having a highly crosslinked structure. Furthermore, in recent years, there has been a demand for reducing and simplifying various processes in order to simplify electrophotographic devices.

[0016] Electrophotographic photoreceptors with a cross-linked structure in the surface layer have the problem that an interface is formed between the underlying layer and the photoreceptor, preventing complete charge transport between the layers, resulting in the generation of ghost images. This problem is usually solved by implementing a static elimination process on the photoreceptor after the electrophotographic process is completed, which temporarily removes the potential difference on the photoreceptor. The static elimination process is usually carried out by irradiating the entire surface with static elimination light, which exposes the entire surface uniformly.

[0017] As described above, due to the recent demand for process simplification, there is a demand for an electrophotographic photoreceptor that is a highly durable photoreceptor and yet can suppress the occurrence of ghost phenomena even when the charge removal process is omitted. As a result of intensive research, the inventors have found that such problems can be improved by including, in a specific ratio, a similar hole transport compound having specific physical property values ​​different from those of a main hole transport compound having a chain polymerizable functional group.

[0018] Specifically, the present invention provides: An electrophotographic photoreceptor having a support, a charge generating layer on the support, a first hole transport layer on the charge generating layer, and a second hole transport layer on the first hole transport layer, wherein the second hole transport layer is a surface layer, the second hole transport layer a hole transporting compound represented by the following formula (1); at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3); The composition contains a copolymer of the above.

[0019] The mass of the hole transport compound represented by the following formula (1) contained in the composition is represented by W1: The mass of the hole transport compound represented by the following formula (2) contained in the composition is represented by W2: When the mass of the hole transport compound represented by the following formula (3) contained in the composition is defined as W3, the value calculated by the following formula (I) is 0.05 mass % to 5.0 mass %, (W2+W3) / (W1+W2+W3)×100(mass%)...Formula (I) and, The energy value of the highest occupied molecular orbital of the hole transport compound represented by the following formula (1) is defined as CTM1HOMO, When the energy value of the highest occupied molecular orbital of at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3) is CTM2HOMO, The CTM1HOMO and the CTM2HOMO satisfy the following formula (II): 0.05(eV)≦|CTM2HOMO|-|CTM1HOMO|≦0.30(eV) ···(II) The energy values ​​of the highest occupied molecular orbitals of the hole transporting compounds represented by the general formulae (1) to (3) are all obtained as a result of energy calculations using the density functional theory B3LYP / 6-31G* after structural optimization. As will be described later, it is preferable that the CTM1HOMO and the CTM2HOMO satisfy the following formula (II)'. 0.15(eV)≦|CTM2HOMO|-|CTM1HOMO|≦0.25(eV) ···(II)'

[0020] [ka] (In formula (1), R 11 and R 12 R each independently represents an alkylene group having 2 to 6 carbon atoms. 13 and R 14 Each of n independently represents a hydrogen atom or a methyl group. 1 is either 0 or 1. R 15represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 11 is an integer between 0 and 5. 11 If x is an integer between 2 and 5, 11 R 15 may be the same or different. 16 represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 12 is an integer between 0 and 4. 12 If x is an integer between 2 and 4, 12 R 16 may be the same or different.)

[0021] [ka] (In formula (2), R 21 and R 22 R each independently represents an alkylene group having 2 to 6 carbon atoms. 23 and R 24 Each of n independently represents a hydrogen atom or a methyl group. 2 is either 0 or 1. R 25 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 21 is an integer between 0 and 5. 21 If x is an integer between 2 and 5, 21 R 25 may be the same or different. 26 represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 22 is an integer between 0 and 4. 22 If x is an integer between 2 and 4, 22 R 26 may be the same or different.)

[0022] [ka] (In formula (3), R 31 and R32 R each independently represents an alkylene group having 2 to 6 carbon atoms. 33 and R 34 Each of n independently represents a hydrogen atom or a methyl group. 3 is either 0 or 1. R 35 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. 31 is an integer between 0 and 5. 31 If x is an integer between 2 and 5, 31 R 35 may be the same or different. 36 represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. 32 is an integer between 0 and 4. 32 If x is an integer between 2 and 4, 32 R 36 may be the same or different.)

[0023] The ghost phenomenon that occurs when no static elimination process is implemented occurs during the series of processes such as exposure, development, and transfer. This is caused by the surface potential difference of the electrophotographic photosensitive member that occurred between the exposed and unexposed areas in the previous process being carried over to the next process, resulting in uneven image density when the next image is output.

[0024] It is believed that the effects of the present invention are exhibited when, as in the present invention, the hole transporting compound present only on the surface layer side contains, at an appropriate ratio, a substance whose highest occupied molecular orbital (HOMO) has a slightly higher energy value than that of the main hole transporting compound. Although the exact mechanism of ghost image suppression is unknown, it is believed to be as follows: By adding another hole transport compound whose hole transport level has a slightly higher energy value than the main hole transport compound contained in the surface layer, hole migration is appropriately delayed in the second hole transport layer, and density differences due to potential unevenness are homogenized during development.

[0025] Because of the good compatibility and affinity with the main hole transporting compound, it is believed that the optimum combination is with a positional isomer having the same main skeleton structure but different substitution positions of the substituents. The energy value of the highest occupied molecular orbital of a hole-transporting compound can be calculated by molecular orbital calculation based on the chemical structure. The calculation can be performed using computational chemistry software such as Gaussian 16 from Gaussian Corporation or Spartan 16 from Wave Function Corporation.

[0026] The numerical values ​​can be determined by inputting the structure of the compound to be calculated, optimizing the structure using semi-empirical molecular orbital methods, and performing energy calculations using density functional theory. The difference in energy value of the highest occupied molecular orbital from that of the main hole-transporting compound is preferably in the range of 0.05 (eV) to 0.30 (eV), more preferably in the range of 0.15 (eV) to 0.25 (eV). If the difference is too small, the effect of the present invention is reduced, whereas if the difference is too large, the hole-transporting property is reduced, and the potential fluctuation of the photoreceptor tends to decrease.

[0027] The second charge transport layer according to the present invention can improve ghost phenomena. In the second charge transport layer according to the present invention, the amount of hole transport compounds represented by formulas (2) and (3) added is preferably 0.05% to 5.0% by mass. 0.1% to 2.0% by mass is more preferable, and 0.2% to 1.0% by mass is even more preferable. If the amount added is too small, the effects of the present invention are less likely to be achieved. On the other hand, adding too many charge transport compounds with different hole transport levels may cause other problems. Adding too many substances with different charge transport levels impairs charge transport properties, resulting in problems such as reduced potential fluctuation during long-term use of the photoreceptor. If the amount is more than approximately 5% by mass, potential fluctuation in low-humidity environments is reduced.

[0028] The polymerizable functional group referred to in the present invention means a functional group that can bond molecules together by a covalent bond when a reaction occurs between molecules having the polymerizable functional group. From the viewpoint of being able to improve the film strength and abrasion resistance of the surface layer, an acryloyloxy group or a methacryloyloxy group is suitable as the chain polymerizable functional group. As a means for polymerizing the chain-polymerizable functional group, a means for applying energy such as ultraviolet light, an electron beam, or heat, or a means for allowing an auxiliary such as a polymerization initiator, or a compound such as an acid, an alkali, or a complex to coexist can be used.

[0029] The second hole transport layer can be formed by forming a coating film of a surface layer coating liquid containing the charge transport compound of the present invention, and drying and / or curing the coating film. Examples of the solvent that can be used in the coating liquid for the second hole transport layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, aliphatic halogenated hydrocarbon-based solvents, aliphatic hydrocarbon-based solvents, and aromatic hydrocarbon-based solvents. The thickness of the second hole transport layer is preferably 0.1 μm or more and 15 μm or less.

[0030] The method for curing the coating film of the surface layer coating liquid (polymerizing the surface layer of the present invention) includes polymerization using heat, light (such as ultraviolet light), or radiation (such as electron beams). Among these, radiation is preferred, and among radiation, electron beams are more preferred. Polymerization using electron beams is preferred because it results in a three-dimensional network structure and improves abrasion resistance. Furthermore, the polymerization reaction is short and efficient, resulting in high productivity. When irradiating with electron beams, accelerators such as scanning, electrocurtain, broad beam, pulse, and laminar types are used.

[0031] When an electron beam is used, the acceleration voltage of the electron beam is preferably 150 kV or less from the viewpoint of suppressing deterioration of material properties due to the electron beam without impairing polymerization efficiency. The electron beam absorbed dose at the surface of the coating film of the surface layer coating solution is preferably 1 kGy or more and 50 kGy or less, and more preferably 5 kGy or more and 10 kGy or less. When the hole transport material of the present invention is polymerized using an electron beam, it is preferable to irradiate the hole transport material with the electron beam in an inert gas atmosphere, such as nitrogen, argon, or helium, and then heat the material in the inert gas atmosphere, in order to prevent the polymerization from being inhibited by oxygen. Next, the overall configuration of the electrophotographic photoreceptor of the present invention will be described.

[0032] <Electrophotographic photoreceptor> A preferred configuration of the electrophotographic photoreceptor in the present invention is a configuration in which a charge generation layer, a first hole transport layer, and a second hole transport layer are laminated in this order on a support. If necessary, a conductive layer or an undercoat layer may be provided between the charge generation layer and the support. In the present invention, the charge generation layer, the first hole transport layer, and the second hole transport layer are collectively referred to as the photosensitive layer.

[0033] <Support> The support used in the present invention is preferably a conductive support made of a conductive material. Examples of the support material include metals or alloys such as iron, copper, gold, silver, aluminum, zinc, titanium, lead, nickel, tin, antimony, indium, chromium, aluminum alloys, and stainless steel. Metal supports or resin supports having a coating formed by vacuum deposition of aluminum, aluminum alloys, indium oxide-tin oxide alloys, or the like can also be used. Supports made by impregnating plastic or paper with conductive particles such as carbon black, tin oxide particles, titanium oxide particles, or silver particles, or supports containing a conductive resin can also be used. The shape of the support can be cylindrical, belt-like, sheet-like, or plate-like, with cylindrical being the most common.

[0034] The surface of the support may be subjected to treatments such as cutting, roughening, and alumite treatment from the viewpoints of suppressing interference fringes due to scattering of laser light, improving surface defects of the support, and improving the conductivity of the support. A conductive layer may be provided between the support and the undercoat layer or charge generating layer described below for the purposes of suppressing interference fringes caused by scattering of lasers, etc., controlling resistance, or covering scratches on the support.

[0035] The conductive layer can be formed by applying a conductive layer coating liquid obtained by dispersing carbon black, a conductive pigment, an electrical resistance adjusting pigment, etc. together with a binder resin, and drying the resulting coating film. A compound that cures and polymerizes upon heating, ultraviolet irradiation, radiation irradiation, etc. may be added to the conductive layer coating liquid. A conductive layer in which a conductive pigment or an electrical resistance adjusting pigment is dispersed tends to have a roughened surface.

[0036] The thickness of the conductive layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 40 μm or less, and even more preferably 1 μm or more and 30 μm or less.

[0037] Examples of binder resins used in the conductive layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenolic resins, melamine resins, silicon resins, epoxy resins, and isocyanate resins.

[0038] Examples of conductive pigments and electrical resistance adjusting pigments include particles of metals (alloys) such as aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, and particles of these metals vapor-deposited on the surface of plastic particles. Also suitable are particles of metal oxides such as zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, and tin oxide doped with antimony or tantalum. These may be used alone or in combination of two or more.

[0039] An undercoat layer (intermediate layer) may be provided between the support or conductive layer and the charge generation layer for the purposes of improving the adhesion of the charge generation layer, improving hole injection from the support, and protecting the charge generation layer against electrical breakdown. The undercoat layer can be formed by applying a coating liquid for the undercoat layer obtained by dissolving a binder resin in a solvent, and drying the resulting coating film.

[0040] Examples of binder resins used in the undercoat layer include polyvinyl alcohol resin, poly-N-vinylimidazole, polyethylene oxide resin, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide resin, N-methoxymethylated nylon 6 resin, copolymer nylon resin, phenol resin, polyurethane resin, epoxy resin, acrylic resin, melamine resin, and polyester resin.

[0041] The undercoat layer may further contain metal oxide particles. Examples of the metal oxide particles include particles containing titanium oxide, zinc oxide, tin oxide, zirconium oxide, and aluminum oxide. The metal oxide particles may be metal oxide particles whose surfaces have been treated with a surface treatment agent such as a silane coupling agent. The thickness of the undercoat layer is preferably from 0.05 to 30 μm, more preferably from 1 to 25 μm The undercoat layer may further contain organic resin particles and a leveling agent.

[0042] <Charge generation layer> Next, the charge generation layer will be described. The charge generation layer can be formed by applying a coating liquid for the charge generation layer obtained by dispersing a charge generation material together with a binder resin and a solvent to form a coating film, and then drying the resulting coating film. The charge generation layer may also be a vapor-deposited film of the charge generation material.

[0043] Examples of charge generation materials used in the charge generation layer include azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium dyes, pyrylium salts, thiapyrylium salts, triphenylmethane dyes, quinacridone pigments, azulenium salt pigments, cyanine dyes, anthanthrone pigments, pyranthrone pigments, xanthene dyes, quinoneimine dyes, and styryl dyes. These charge generation materials may be used alone or in combination of two or more. Among these charge generation materials, phthalocyanine pigments and azo pigments are preferred, and phthalocyanine pigments are particularly preferred, from the viewpoint of achieving excellent sensitivity.

[0044] Among phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine exhibit particularly excellent charge generation efficiency. Furthermore, among hydroxygallium phthalocyanines, the following hydroxygallium phthalocyanine crystal is more preferred from the viewpoint of obtaining even better sensitivity. Hydroxygallium phthalocyanine crystals with a crystalline form showing peaks at Bragg angles 2θ of 7.4°±0.3° and 28.2°±0.3° in CuKα characteristic X-ray diffraction

[0045] Examples of binder resins used in the charge generating layer include polymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polysulfone resin, polyphenylene oxide resin, polyurethane resin, cellulose resin, phenol resin, melamine resin, silicone resin, and epoxy resin.

[0046] The mass ratio of the charge generating material to the binder resin is preferably in the range of 1:0.3 to 1:4. The thickness of the charge generating layer is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less.

[0047] <First Hole Transport Layer> Next, the first hole transport layer will be described. The first hole transport layer can be formed by forming a coating film of a hole transport layer coating liquid in which a hole transport material and a binder resin are mixed in a solvent, and drying this coating film. The hole transport material and binder resin used in the hole transport layer will be described below.

[0048] Examples of hole transporting substances include carbazole compounds, hydrazone compounds, N,N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, styryl compounds, and stilbene compounds.

[0049] Examples of binder resins include acrylic acid esters, methacrylic acid esters, polyvinyl alcohol resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, etc. In addition, curable resins such as curable phenolic resins, curable urethane resins, curable melamine resins, curable epoxy resins, curable acrylic resins, and curable methacrylic resins can also be used.

[0050] Examples of the solvent used in the coating liquid for the first hole transport layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, aliphatic halogenated hydrocarbon-based solvents, and aromatic hydrocarbon-based solvents. The thickness of the first hole transport layer is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less, and even more preferably 5 μm or more and 40 μm or less.

[0051] Various additives can be added to each layer of the electrophotographic photoreceptor of the present invention, specifically, organic pigments, organic dyes, coating surface modifiers, electron transport agents, oils, waxes, antioxidants, light absorbers, polymerization initiators, radical deactivators, organic resin fine particles, inorganic particles, etc. The surface of each layer of the electrophotographic photosensitive member may be subjected to surface treatment using an abrasive sheet, a shape transfer member, glass beads, zirconia beads, etc. Furthermore, unevenness may be formed on the surface using a constituent material of the coating liquid.

[0052] When applying the coating solution for each of the above layers, any known coating method can be used, such as dip coating, spray coating, circular amount-controlled (ring) coating, spin coating, roller coating, Mayer bar coating, or blade coating. Next, a process cartridge equipped with the electrophotographic photosensitive member of the present invention and an image forming process will be described.

[0053] <Process cartridge and image forming process> FIG. 1 shows an example of the configuration of a process cartridge. In FIG. 1, a cylindrical electrophotographic photosensitive member 1 is rotated in the direction of the arrow at a predetermined peripheral speed. The peripheral surface of the rotated electrophotographic photosensitive member 1 is uniformly charged to a predetermined positive or negative potential by charging means 2. Next, the charged peripheral surface of the electrophotographic photosensitive member 1 is exposed to exposure light (image exposure light) 3 output from exposure means (not shown) such as slit exposure or laser beam scanning exposure. In this way, an electrostatic latent image corresponding to a target image is sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1. The voltage applied to the charging means (such as a charging roller) 2 may be a voltage in which an AC component is superimposed on a DC component, or a voltage consisting of only a DC component.

[0054] The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed into a toner image by the toner contained in the developer of the developing means 4. Next, the toner image formed and carried on the peripheral surface of the electrophotographic photosensitive member 1 is sequentially transferred onto a transfer material (paper, intermediate transfer member, etc.) 6 by a transfer bias from a transfer means (transfer roller, etc.) 5. The transfer material 6 is fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

[0055] After the toner image is transferred, the surface of the electrophotographic photoreceptor 1 is neutralized by pre-exposure light 7 from a pre-exposure means (not shown), and then the surface is cleaned by removing residual toner from the surface by a cleaning means 8, and the electrophotographic photoreceptor 1 is then reused for image formation. The pre-exposure means may be placed either before or after the cleaning step. The process cartridge according to the present invention does not require a pre-exposure means.

[0056] The electrophotographic photosensitive member 1 may be mounted in an electrophotographic apparatus such as a copying machine or a laser beam printer. Alternatively, a process cartridge 9 configured by housing a plurality of components, such as the electrophotographic photosensitive member 1, charging means 2, developing means 4, and cleaning means 8, in a container and integrally supporting them may be configured to be detachably attachable to the main body of the electrophotographic apparatus. In FIG. 1, the electrophotographic photosensitive member 1, charging means 2, developing means 4, and cleaning means 8 are integrally supported to form a process cartridge 9 that is detachably attachable to the main body of the electrophotographic apparatus. Next, an electrophotographic apparatus equipped with the electrophotographic photosensitive member of the present invention will be described.

[0057] FIG. 2 shows an example of the configuration of the electrophotographic apparatus of the present invention. A yellow process cartridge 17, a magenta process cartridge 18, a cyan process cartridge 19, and a black process cartridge 20 are arranged side by side along the intermediate transfer member 10. As shown in FIG. 2, the diameter, constituent materials, developer, charging method, and other means of the electrophotographic photosensitive member do not necessarily need to be the same for each color. For example, in the electrophotographic apparatus of FIG. 2, the diameter of the electrophotographic photosensitive member for black is larger than that for the colored colors (yellow, magenta, and cyan). Furthermore, while the charging method for the colored colors is to apply a voltage in which an AC component is superimposed on a DC component, a method using corona discharge is adopted for the black color.

[0058] When the image formation operation begins, toner images of each color are sequentially superimposed on the intermediate transfer body 10 according to the image formation process described above. In parallel, transfer paper 11 is sent out from paper feed tray 13, transported along paper feed path 12, and fed to secondary transfer means 14 in synchronization with the rotation of the intermediate transfer body. The toner image on the intermediate transfer body 10 is transferred onto the transfer paper 11 by a transfer bias from secondary transfer means 14. The toner image transferred onto the transfer paper 11 is transported along paper feed path 12, fixed on the transfer paper by fixing means 15, and then discharged from paper discharge section 16.

[0059] Next, examples of the hole transport compound having a chain-polymerizable functional group of the present invention represented by the formula (1) are shown below, although the present invention is not limited to these examples.

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] Examples of the compound represented by the formula (2) are shown below, but are not limited to these examples.

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka] Examples of the compound represented by the formula (3) are shown below, but are not limited to these examples.

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] A typical synthesis example of the hole transporting compound used in the present invention is shown below. <Synthesis Example 1> A synthesis example of the hole transporting compound having a bifunctional polymerizable acrylic group, represented by the above formula (2) and represented by Exemplary Compound No. 2-3, will be shown below.

[0074] [ka]

[0075] A triarylamine was synthesized using the iodine compound and amine compound shown in reaction formula (1). 47.9 parts of the iodine compound, 36.0 parts of the amine compound in the formula, and 60 parts of o-dichlorobenzene were mixed in a reaction vessel, and 18.4 parts of potassium carbonate and 9.2 parts of copper powder were added. The reaction was carried out at an internal temperature of approximately 210°C. The reaction was carried out with stirring for approximately 16 hours. After the reaction, the mixture was filtered, washed with toluene, and concentrated to obtain a crude product.

[0076] [ka]

[0077] Subsequently, the obtained intermediate was hydrolyzed to convert the acetate ester into a hydroxy group. 75 parts of tetrahydrofuran, 75 parts of methanol, and 55 parts of 24% aqueous sodium hydroxide solution were mixed, heated to an internal temperature of 60°C, stirred, and reacted for 1 hour to carry out hydrolysis. After the reaction, the reaction mixture was extracted with ethyl acetate, and the organic layer was washed with water, washed with brine, dehydrated, and concentrated. The product was purified by silica gel chromatography to obtain a dihydroxy intermediate. Yield: 30.5 parts, Yield (2 steps): 64.5%

[0078] [ka]

[0079] 30 parts of the dihydroxy intermediate obtained by the above reaction, 340 parts of toluene, and 0.6 parts of 4-methoxyphenol were mixed, and 13.3 parts of acrylic acid were added to a reaction vessel. 1.3 parts of p-toluenesulfonic acid monohydrate was added, and the mixture was heated at 112°C under reflux conditions for 6 hours to carry out an acrylic reaction. After the reaction, the mixture was cooled, neutralized with 10% aqueous sodium hydroxide solution, extracted with ethyl acetate, washed with water, dehydrated, and concentrated to obtain a crude product.

[0080] The crude product was then purified by silica gel column chromatography to obtain a hole transporting compound having a polymerizable functional group. Yield: 31.0 parts, 80.9% Furthermore, the obtained hole transporting compound was mixed with the solvent and the amount of the solvent was adjusted to obtain a varnish. Similarly, other hole transporting compounds represented by the formulas (2) and (3) can be synthesized. [Example]

[0081] The present invention will be described in more detail below with reference to specific examples. In the examples, "parts" means "parts by mass." In addition, the electrophotographic photoreceptor will hereinafter also be referred to simply as "photoreceptor." <Preparation of Electrophotographic Photoreceptor>

[0082] Example 1 A cylindrical aluminum cylinder having an outer diameter of 30.0 mm, a length of 357.5 mm, and a wall thickness of 0.7 mm was used as the support (conductive support). Next, zinc oxide particles (specific surface area: 19 m 2 / g, powder resistivity: 4.7×10 6 Ten parts of zinc oxide (viscosity: Ω·cm) were mixed with 50 parts of toluene and stirred, to which 0.08 parts of a silane coupling agent was added, followed by stirring for 6 hours. The toluene was then distilled off under reduced pressure, and the particles were dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles. N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent.

[0083] Next, 15 parts of polyvinyl butyral resin (weight average molecular weight: 40,000, product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 15 parts of blocked isocyanate (product name: Duranate TPA-B80E, manufactured by Asahi Kasei Chemicals Corporation) were prepared. These were dissolved in a mixed solution of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. 80.8 parts of the surface-treated zinc oxide particles and 0.8 parts of 2,3,4-trihydroxybenzophenone (manufactured by Wako Pure Chemical Industries, Ltd.) were added to this solution, and the mixture was dispersed in a sand mill using 0.8 mm diameter glass beads at 23±3°C for 3 hours. After dispersion, the following materials were added and stirred to prepare a coating solution for the undercoat layer. Silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Co., Ltd.) 0.01 part Cross-linked polymethyl methacrylate (PMMA) particles (product name: TECHPOLYMER SSX-102, manufactured by Sekisui Plastics Co., Ltd., average primary particle size 2.5 μm) 5.6 parts

[0084] This coating solution for the undercoat layer was dip-coated onto the support to form a coating film, and the resulting coating film was dried at 160° C. for 40 minutes to form an undercoat layer with a thickness of 18 μm. Next, two parts of hydroxygallium phthalocyanine crystals (charge-generating material) were prepared. These crystals had peaks at Bragg angles 2θ ±0.2 (7.4° and 28.2°) in CuKα characteristic X-ray diffraction. Furthermore, 0.02 parts of a calixarene compound represented by the following formula (A), 1 part of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 60 parts of cyclohexanone were prepared. These were placed in a sand mill using 1 mm diameter glass beads and dispersed for 4 hours. Then, 70 parts of ethyl acetate were added to prepare a charge-generating layer coating solution. This charge-generating layer coating solution was dip-coated onto the undercoat layer, and the resulting coating was dried at 90°C for 15 minutes to form a 0.18 μm-thick charge-generating layer.

[0085] [ka]

[0086] Next, the following materials were prepared to form a first hole transport layer. 6 parts of a compound represented by the following formula (B): 3 parts of a compound represented by the following formula (C): 1 part of a compound represented by the following formula (D): 10 parts bisphenol Z polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation)

[0087] These were dissolved in a mixed solvent of 35 parts o-xylene, 35 parts dimethoxymethane, and 30 parts methyl benzoate to prepare a coating solution for the charge transport layer. The coating solution for the charge transport layer was dip-coated onto the charge generation layer, and the resulting coating was dried at 110°C for 50 minutes to form a charge transport layer with a thickness of 18 μm.

[0088] [ka]

[0089] <Formation of second hole transport layer> 1.5 parts of a fluorine atom-containing acrylic resin (weight average molecular weight: 83,000, copolymerization ratio (F1) / (F2)=1 / 1 (molar ratio)) having a repeating structural unit represented by the following formula (F1) and a repeating structural unit represented by the following formula (F2),

[0090] [ka] The mixture was dissolved in a mixed solvent of 45 parts of 1-propanol and 45 parts of Zeorora (registered trademark) H (manufactured by Zeon Corporation). Then, 30 parts of fluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was added, and the mixture was dispersed using a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a fluoroethylene resin dispersion.

[0091] Next, the following materials were stirred and uniformly dispersed to prepare a coating liquid for a protective layer. 9.90 parts of hole transporting compound shown in Exemplary Compound No. 1-3 Compound shown in Example Compound No. 2-3 0.08 parts Compound shown in Example Compound No. 3-3 0.02 parts 16.60 parts of the fluoroethylene resin dispersion 1-propanol 7.20 parts Zeorora H (cyclic HFC c-C5F7H3) 7.20 parts

[0092] This protective layer coating solution was dip-coated onto the charge transport layer, and the resulting coating was dried at 50° C. for 10 minutes, followed by polymerization and curing treatment by electron beam irradiation and heating under the following conditions. In an atmosphere with an oxygen concentration of 50 ppm or less, the aluminum cylinder was rotated at a speed of 300 rpm and irradiated with electron beams using an electron beam irradiator under the following conditions: irradiation distance 30 mm, acceleration voltage 70 kV, beam current 8 mA, irradiation time 3.0 seconds. After electron beam irradiation, the surface of the protective layer coating was allowed to reach 135°C over 24 seconds while maintaining the oxygen concentration of 50 ppm or less.

[0093] Next, the aluminum cylinder was taken out into the air and heated at 100° C. for a further 12 minutes to form a protective layer with a thickness of 5 μm. The energy value of the highest occupied molecular orbital of the hole transporting compound used in the second charge transporting layer was calculated as follows.

[0094] The computational chemistry application used was Spartan 16 manufactured by Wave Function. After inputting the chemical structure and adjusting the conformation, structural optimization was performed using the semi-empirical molecular orbital method (PM3). Next, density functional calculations were performed on each molecular structure to calculate energy values. B3LYP 6-31G* was used as the basis function. When two or more hole transport compounds represented by formula (2) and formula (3) are contained in the second hole transport layer of the present invention, the values ​​are determined by taking a weighted average of the physical property values ​​of each compound individually, taking into account the mass ratio of the materials used. The calculated energy values ​​are shown in Table 1.

[0095] Next, a mold was placed in a pressure contact shape transfer processing device, and the surface of the electrophotographic photosensitive member before the formation of the recesses was processed. FIG. 3 is a schematic diagram showing an example of an apparatus for transferring a shape by pressure contact onto the surface of an electrophotographic photosensitive member. As shown in FIG. 3, the apparatus includes a mold 22, a pressure member 23, and a support member 24. FIG. 4 is a diagram showing the molds used in the examples and comparative examples. The mold shown in FIG. 4 was placed in the pressure contact shape transfer processing device shown in FIG. 3, and the surface of the electrophotographic photosensitive member 21 before the formation of the recesses was processed. Fig. 4(a) is a top view showing an outline of the mold. Fig. 4(b) is a schematic cross-sectional view of the convex portion of the mold in the axial direction of the electrophotographic photosensitive member 21 (cross-sectional view taken along the SS' section in Fig. 4(a)). Fig. 4(c) is a cross-sectional view of the convex portion of the mold in the circumferential direction of the electrophotographic photosensitive member 21 (cross-sectional view taken along the T-T' section in Fig. 4(a)).

[0096] The mold shown in FIG. 4 has protrusions with a maximum width X of 50 μm, a maximum length Y of 75 μm, an area ratio of 56%, and a height H of 4 μm. The maximum width X is the maximum width in the axial direction of the electrophotographic photosensitive member 21 when the convex portion on the mold is viewed from above. The maximum length Y is the maximum length in the circumferential direction of the electrophotographic photosensitive member 21 when the convex portion on the mold is viewed from above. The area ratio is the ratio of the area of ​​the convex portions to the entire surface when the mold is viewed from above. During processing, the temperatures of the electrophotographic photosensitive member 21 and the mold were controlled so that the surface temperature of the electrophotographic photosensitive member 21 would be 120° C. Then, while pressing the electrophotographic photosensitive member 21 against the mold at a pressure of 7.0 MPa, the electrophotographic photosensitive member 21 was rotated in the circumferential direction, thereby forming recesses on the entire surface of the surface layer (circumferential surface) of the electrophotographic photosensitive member 21. In this way, the electrophotographic photosensitive member 21 was manufactured.

[0097] The surface of the obtained electrophotographic photoreceptor 21 was magnified and observed using a laser microscope (product name: X-100, manufactured by Keyence Corporation) with a 50x lens, and the recesses provided on the surface of the electrophotographic photoreceptor 21 were observed. During observation, adjustments were made so that there was no tilt in the longitudinal direction of the electrophotographic photoreceptor 21 and that the focus was on the vertex of the arc of the electrophotographic photoreceptor 21 in the circumferential direction. The images obtained through the magnified observation were linked using an image linking application to obtain a square area with a side length of 500 μm. Then, the obtained results were filtered using the attached image analysis software, with image processing height data selected and a median filter type.

[0098] As a result of the observation, the depth of the recess was 2 μm, the width in the axial direction of the opening was 50 μm, the length in the circumferential direction of the opening was 75 μm, and the area was 140,000 μm 2 The area is the area of ​​the recesses when the surface of the electrophotographic photosensitive member 21 is viewed from above, and means the total area of ​​the openings of the recesses. In this manner, the photoreceptor according to Example 1 was produced.

[0099] Examples 2 to 17 A protective layer coating solution was prepared in the same manner as in Example 1, except that the materials shown in Table 1A were used instead of the hole transporting compound used in Example 1. A photoreceptor was produced in the same manner as in Example 1 except for the above.

[0100] Example 18 Instead of the hole-transporting compound used in Example 1, the materials shown in Table 1A were used, and 2.5 parts of a polymerizable compound having no hole-transporting property and represented by the following formula (G) was used, to prepare a protective layer coating solution in the same manner as in Example 1. Otherwise, a photoreceptor was produced in the same manner as in Example 1.

[0101] [ka]

[0102] Examples 19 to 27 Instead of the hole-transporting compound used in Example 1, the materials shown in Table 1A and 2.5 parts of the polymerizable compound represented by formula (G) and not having hole-transporting properties were used to prepare a protective layer coating solution in the same manner as in Example 1. A photoreceptor was produced in the same manner as in Example 1 except for the above.

[0103] Example 28 Instead of the hole transporting compound used in Example 1, In addition to 6.93 parts of the hole transporting compound represented by Exemplary Compound No. 1-3, 0.056 parts of the compound represented by Exemplary Compound No. 2-3, and 0.014 parts of the compound represented by Exemplary Compound No. 3-3, Using 2.97 parts of the hole transporting compound represented by Exemplary Compound No. 1-12, 0.024 parts of the compound represented by Exemplary Compound No. 2-12, and 0.006 parts of the compound represented by Exemplary Compound No. 3-12, A coating liquid for a protective layer was prepared in the same manner as in Example 1. A photoreceptor was produced in the same manner as in Example 1 except for the above.

[0104] [Comparative Examples 1, 3, and 5] A photoreceptor was prepared in the same manner as in Example 1, except that the hole transporting compounds used in Example 1 were replaced with the exemplary compounds represented by the formula (1) shown in Table 1.

[0105] [Comparative Examples 2, 4, and 6] Instead of the hole transporting compound used in Example 1, 9.90 parts of the exemplary compound represented by the formula (1) and 0.10 parts of the exemplary compound represented by the formula (2) shown in Table 1 were used to prepare a protective layer coating solution in the same manner as in Example 1. Otherwise, a photoreceptor was produced in the same manner as in Example 1.

[0106] [Comparative Examples 7, 9, and 11] Instead of the hole-transporting compound used in Example 1, 7.50 parts of the exemplary compound represented by formula (1) shown in Table 1 and 2.5 parts of the polymerizable compound represented by formula (G) having no hole-transporting property were used to prepare a protective layer coating solution in the same manner as in Example 1. Otherwise, a photoreceptor was produced in the same manner as in Example 1.

[0107] [Comparative Examples 8, 10, and 12] Instead of the hole transporting compound used in Example 1, the following materials shown in Table 1 were used to prepare a protective layer coating solution in the same manner as in Example 1. Otherwise, a photoreceptor was produced in the same manner as in Example 1. 7.0125 parts of the exemplary compound represented by formula (1) 0.4875 parts of the exemplary compound represented by formula (2) 2.5 parts of a polymerizable compound represented by the formula (G) that does not have hole transport properties

[0108] <Evaluation of ghost phenomenon suppression effect> Using the produced example photoreceptors 1 to 28 and comparative example photoreceptors 1 to 12, ghost images were evaluated as follows. The electrophotographic apparatus used was a modified copy machine, product name iR-ADVC5560, manufactured by Canon Inc. The apparatus was set so that no static elimination light was emitted during image output, and the manufactured electrophotographic photosensitive member was mounted in a black process cartridge, which was then mounted in the station for the black process cartridge, and an image was output.

[0109] The evaluation was carried out in an environment with a temperature of 23°C and a relative humidity of 50%. First, 5,000 full-color images (text images with a print rate of 1% for each color) were printed on A4-sized plain paper, and then one solid white image, five images for evaluating the ghost phenomenon, one solid black image, and five images for evaluating the ghost phenomenon were printed in succession in this order.

[0110] As shown in Fig. 5, the image for evaluating the ghost phenomenon was created by outputting a square "solid image 52" in a "white image 51" at the beginning of the image, and then creating a "halftone image 53 with a one-dot knight pattern" as shown in Fig. 6. In Fig. 5, the "ghost part 54" is the part where the ghost phenomenon caused by the "solid image 52" may appear. The ghost phenomenon was evaluated by measuring the difference in density between the image density of a halftone image with a one-dot knight's horse pattern and the image density of the ghost area. Using a spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite), the density difference was measured at 10 points within one ghost phenomenon evaluation image. This procedure was repeated for all 10 ghost phenomenon evaluation images, and the average value of a total of 100 points was calculated to evaluate the Macbeth density difference. The evaluation results are shown in Table 2.

[0111] <Evaluation: Evaluation of potential fluctuations during repeated use in a low-temperature, low-humidity environment> The photoreceptors according to Examples 1 to 28 and Comparative Examples 1 to 12 were used to evaluate potential fluctuations during repeated use of the photoreceptors in a low-temperature, low-humidity environment under the following conditions. The electrophotographic apparatus used was a modified copy machine manufactured by Canon Inc., product name iR-ADVC5560. The modification was made so that the potential charged from the charging roller to the photosensitive member and the image exposure laser power could be adjusted. The electrophotographic apparatus and electrophotographic photosensitive member were left standing in a low-temperature, low-humidity environment of a temperature of 15°C and a relative humidity of 10% for 48 hours or more, and then the electrophotographic photosensitive member was mounted in a cyan cartridge of the electrophotographic apparatus.

[0112] The surface potential of the electrophotographic photosensitive member was measured by removing the developing cartridge from the evaluation device and inserting a potential measuring device into that position. The potential measuring device was configured to place a potential measuring probe at the developing position of the developing cartridge. The position of the potential measuring probe relative to the electrophotographic photosensitive member was the center in the axial direction of the cylindrical electrophotographic photosensitive member, with a gap of 3 mm from the surface of the electrophotographic photosensitive member.

[0113] The AC component of the charging roller was set to 1500 Vpp, 1500 Hz, and the initial dark potential (VDa) was adjusted to -700 V, and the initial light potential (VLa) before durability test by image exposure with laser exposure irradiation was adjusted to -200 V, and the set values ​​were recorded. These operations were similarly performed for each electrophotographic photoreceptor to be evaluated. A band image with an image density of 1% was printed, and 1000 sheets were passed continuously. After the durability test was completed, the light area potential (VLb) after passing 1000 sheets was immediately measured using the above-mentioned potential measuring device. The amount of change between the initial light area potential (VLa) before the paper feed and the light area potential (VLb) after the paper feed was measured and defined as the light area potential change ΔVL(ab). The results are shown in Table 2.

[0114] [Table 1A]

[0115] [Table 1B]

[0116] [Table 2A]

[0117] [Table 2B] [Explanation of symbols]

[0118] 1. Electrophotographic photoreceptor 2. Charging means 3‥‥Exposure light 4. Developing method 5. Transfer means 6. Transfer material 7. Pre-exposure light 8. Cleaning means 9. Process cartridge 10. Intermediate transfer body 11. Transfer paper 12. Paper feed path 13. Paper feed tray 14. Secondary transfer means 15. Fixing means 16. Paper ejection section 17. Yellow process cartridge 18. Magenta process cartridge 19. Cyan process cartridge 20. Black process cartridge

Claims

1. An electrophotographic photoreceptor having a support, a charge generating layer on the support, a first hole transport layer on the charge generating layer, and a second hole transport layer on the first hole transport layer, wherein the second hole transport layer is a surface layer, the second hole transport layer a hole transporting compound represented by the following formula (1); at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3); The composition contains a copolymer of The mass of the hole transport compound represented by the following formula (1) contained in the composition is represented by W1: The mass of the hole transport compound represented by the following formula (2) contained in the composition is represented by W2: When the mass of the hole transport compound represented by the following formula (3) contained in the composition is W3, The value calculated by the following formula (I) is 0.05% by mass to 5.0% by mass, (W2+W3) / (W1+W2+W3)×100 (mass%)...(I) and, The energy value of the highest occupied molecular orbital of the hole transport compound represented by the following formula (1), obtained as a result of energy calculation by the density functional theory B3LYP / 6-31G* after structural optimization of the hole transport compound, is defined as CTM1HOMO, When the energy value of the highest occupied molecular orbital of at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3) after structural optimization is obtained as a result of energy calculation by density functional theory B3LYP / 6-31G*, the following formula (3) is defined as CTM2HOMO: The CTM1 HOMO and the CTM2 HOMO satisfy the following formula (II): An electrophotographic photoreceptor characterized by: 0.05 (eV)≦|CTM2HOMO|-|CTM1HOMO|≦0.30 (eV) ... (II) 【Chemical 1】 (In formula (1), R １１ and R １２ R each independently represents an alkylene group having 2 to 6 carbon atoms. １３ and R １４ Each of n independently represents a hydrogen atom or a methyl group. １ is 1. R １５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. １１ is an integer from 0 to 5. １１ is an integer from 2 to 5, １１ R １５ may be the same or different. １６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. １２ is an integer from 0 to 4. １２ is an integer from 2 to 4, １２ R １６ may be the same or different.) 【Chemistry 2】 (In formula (2), R ２１ and R ２２ R each independently represents an alkylene group having 2 to 6 carbon atoms. ２３ and R ２４ Each of n independently represents a hydrogen atom or a methyl group. ２ is 1. R ２５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. ２１ is an integer from 0 to 5. ２１ is an integer from 2 to 5, ２１ R ２５ may be the same or different. ２６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ２２ is an integer from 0 to 4. ２２ is an integer from 2 to 4, ２２ R ２６ may be the same or different.) 【Chemistry 3】 (In formula (3), R ３１ and R ３２ R each independently represents an alkylene group having 2 to 6 carbon atoms. ３３ and R ３４ Each of n independently represents a hydrogen atom or a methyl group. ３ is 1. R ３５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. ３１ is an integer from 0 to 5. ３１ is an integer from 2 to 5, ３１ R ３５ may be the same or different. ３６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ３２ is an integer from 0 to 4. ３２ is an integer from 2 to 4, ３２ R ３６ may be the same or different.)

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the CTM1HOMO and the CTM2HOMO satisfy the following formula (II)': 0.15 (eV) ≦ | CTM2HOMO | - | CTM1HOMO | ≦ 0.25 (eV) ... (II)'

3. 3. The electrophotographic photoreceptor according to claim 1, wherein the value calculated by the formula (I) is 0.1% by mass to 2.0% by mass.

4. 4. The electrophotographic photoreceptor according to claim 3, wherein the value calculated by the formula (I) is 0.2% by mass to 1.0% by mass.

5. An electrophotographic photoreceptor described in any one of claims 1 to 4, wherein the composition contains a hole transporting compound represented by formula (1) and a hole transporting compound represented by formula (3).

6. In the formula (1), R １１ and R １２ are each independently an alkylene group having 2 to 5 carbon atoms, and in the formula (2), R ２１ and R ２２ are each independently an alkylene group having 2 to 5 carbon atoms, and in the formula (3), R ３１ and R ３２ and each independently represent an alkylene group having 2 to 5 carbon atoms.

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

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

9. A method for producing an electrophotographic photoreceptor comprising: a support; a charge generating layer on the support; a first hole transport layer on the charge generating layer; and a second hole transport layer on the first hole transport layer, the second hole transport layer being a surface layer, The manufacturing method comprises: forming a coating film of the coating liquid for the second hole transport layer, the coating liquid containing a hole transport compound represented by the following formula (1) and at least one hole transport compound selected from the group consisting of a hole transport compound represented by the following formula (2) and a hole transport compound represented by the following formula (3); copolymerizing the composition contained in the coating to form the second hole transport layer of the electrophotographic photoreceptor. and The second hole transport layer coating liquid contains The mass of the hole transport compound represented by the following formula (1) is W1, The mass of the hole transport compound represented by the following formula (2) is W2, When the mass of the hole transport compound represented by the following formula (3) is W3, The value calculated by the following formula (I) is 0.05% by mass to 5.0% by mass, (W2+W3) / (W1+W2+W3)×100 (mass%)...Formula (I) and, The energy value of the highest occupied molecular orbital of the hole transport compound represented by the following formula (1), obtained as a result of energy calculation by the density functional theory B3LYP / 6-31G* after structural optimization of the hole transport compound, is defined as CTM1HOMO, When the energy value of the highest occupied molecular orbital of at least one hole transport compound selected from the group consisting of hole transport compounds represented by the following formula (2) and hole transport compounds represented by the following formula (3) after structural optimization is obtained as a result of energy calculation by density functional theory B3LYP / 6-31G*, the following formula (3) is defined as CTM2HOMO: The method for producing an electrophotographic photoreceptor is characterized in that the CTM1HOMO and the CTM2HOMO satisfy the following formula (II): 0.05 (eV)≦|CTM2HOMO|-|CTM1HOMO|≦0.30 (eV) ... (II) 【Chemistry 4】 (In formula (1), R １１ and R １２ R each independently represents an alkylene group having 2 to 6 carbon atoms. １３ and R １４ Each of n independently represents a hydrogen atom or a methyl group. １ is 1. R １５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. １１ is an integer from 0 to 5. １１ is an integer from 2 to 5, １１ R １５ may be the same or different. １６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. １２ is an integer from 0 to 4. １２ is an integer from 2 to 4, １２ R １６ may be the same or different.) 【Chemistry 5】 (In formula (2), R ２１ and R ２２ R each independently represents an alkylene group having 2 to 6 carbon atoms. ２３ and R ２４ Each of n independently represents a hydrogen atom or a methyl group. ２ is 1. R ２５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. ２１ is an integer from 0 to 5. ２１ is an integer from 2 to 5, ２１ R ２５ may be the same or different. ２６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ２２ is an integer from 0 to 4. ２２ is an integer from 2 to 4, ２２ R ２６ may be the same or different.) 【Chemistry 6】 (In formula (3), R ３１ and R ３２ R each independently represents an alkylene group having 2 to 6 carbon atoms. ３３ and R ３４ Each of n independently represents a hydrogen atom or a methyl group. ３ is 1. R ３５ represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. ３１ is an integer from 0 to 5. ３１ is an integer from 2 to 5, ３１ R ３５ may be the same or different. ３６ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ３２ is an integer from 0 to 4. ３２ is an integer from 2 to 4, ３２ R ３６ may be the same or different.)

Images