Electrophotographic photoreceptor, process cartridge and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor which offers both high durability and high sensitivity.SOLUTION: An electrophotographic photoreceptor is provided, comprising a support body, a charge generation layer formed on the support body, and a charge transport layer formed on the charge generation layer, where the charge transport layer corresponds to a surface layer and contains a polyester resin having a structure represented by a formula (1) and a charge transport compound having a structure represented by a formula (HTM1).SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Electrophotographic photoreceptors mounted in electrophotographic apparatuses or process cartridges are generally function-separated laminated photoreceptors having a charge generating layer containing a charge generating substance and a charge transport layer containing a charge transport substance. Furthermore, in the electrophotographic process, there has been an increasing demand in recent years for large-volume printing and faster printing speeds, and development is underway to achieve both excellent mechanical strength and electrical properties in the charge transport layer, which often serves as the surface layer of an electrophotographic photoreceptor.

[0003] Conventionally, polycarbonate resins have been widely used as binder resins for the charge transport layer of electrophotographic photoreceptors, but Patent Document 1 proposes using polyarylate resins, which have higher mechanical strength than polycarbonate resins, to further improve the durability of electrophotographic photoreceptors. Polyarylate resins are a type of aromatic dicarboxylic acid polyester resin. Furthermore, Patent Documents 2 and 3 propose photoreceptors with improved durability or electrical properties by incorporating a charge transport material and a polyarylate resin in the photosensitive layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-039521 [Patent Document 2] JP 2007-72277 A [Patent Document 3] JP 2020-181012 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in response to the recent rapid progress in extending the life and increasing the speed of electrophotographic processes, various improvements have been attempted by using polyarylate resins in the charge transport layer of electrophotographic photoreceptors. However, according to the investigations of the present inventors, it has been found that as the speed of electrophotographic processes increases, when a polyarylate resin is used in a charge transport layer, a problem arises in that the sensitivity is insufficient compared to when a polycarbonate resin is used.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an electrophotographic photoreceptor which achieves both high durability and high sensitivity at a high level, and a process cartridge and an electrophotographic apparatus which use the electrophotographic photoreceptor. [Means for solving the problem]

[0007] The above object can be achieved by the present invention described below. That is, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a charge generating layer formed on the support and a charge transporting layer formed on the charge generating layer, the charge transporting layer being a surface layer, The charge transport layer comprises: A polyester resin having a structure represented by the following formula (1): Contains a charge transporting compound represented by the following formula (HTM1): It is characterized by: [ka] X 1 represents a divalent group represented by formula (1A), formula (1B), formula (1C), formula (1D), or formula (1E). [ka] [ka] [ka] [ka] [ka] [ka]

[0008] The present invention also provides a process cartridge which integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and is detachably mountable to the main body of an electrophotographic apparatus. The present invention also relates to an electrophotographic apparatus having the above electrophotographic photoreceptor, a charging means, an exposing means, a developing means and a transferring means. Effect of the Invention

[0009] According to the present invention, it is possible to provide an electrophotographic photoreceptor that can simultaneously achieve high levels of high durability and high sensitivity required of an electrophotographic photoreceptor, and a process cartridge and an electrophotographic apparatus that use the electrophotographic photoreceptor. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram showing an example of a layer structure of an electrophotographic photoreceptor according to the present invention. [Diagram 2] FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus equipped with a process cartridge having an electrophotographic photosensitive member according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below with reference to preferred embodiments. The electrophotographic photoreceptor of the present invention has a support, a charge generating layer formed on the support, and a charge transporting layer formed on the charge generating layer, and the surface layer is the charge transporting layer, and is characterized in that the charge transporting layer contains a polyester resin having a structure represented by the following formula (1) and a charge transporting compound represented by the following formula (HTM1). [ka] X 1 represents a divalent group represented by formula (1A), formula (1B), formula (1C), formula (1D), or formula (1E). [ka] [ka] [ka] [ka] [ka] [ka]

[0012] The present inventors speculate as follows about the reason why the electrophotographic photoreceptor of the present invention can achieve both high durability and high sensitivity at a high level. When a polyester resin and a charge transport compound are present in the charge transport layer, the amine moiety of the charge transport compound coordinates with the ester moiety of the polyester resin. In this case, when a charge transport compound of formula (HTM1) is used for a polyester resin having a structural unit of formula (1), the charge transport compound coordinates with the polyester resin from a direction with less steric hindrance. As a result, the molecules of the charge transport compound in the charge transport layer are aligned, improving hole transportability, and thus dramatically improving sensitivity, making it possible to achieve both high durability and high sensitivity.

[0013] The content of the charge transport compound in the charge transport layer is preferably 60% by mass or more and 120% by mass or less based on the content of the polyester resin, which allows the electrophotographic photoreceptor of the present invention to achieve both high levels of abrasion resistance and high sensitivity.

[0014] The polyester resin used in the charge transport layer of the electrophotographic photoreceptor of the present invention has a structural unit represented by the above formula (1), and the content ratio thereof is arbitrary, but from the viewpoint of improving sensitivity, the structural unit represented by the formula (1) is preferably contained in a mass ratio of 50% to 100% based on the total structural units in the polyester resin. The content ratio can be calculated from the 1H-NMR spectrum obtained by measuring the 1H-NMR spectrum of the polyester resin using a proton nuclear magnetic resonance spectrometer.

[0015] In addition, the polyester resin having the structural unit represented by the above formula (1) used in the charge transport layer of the electrophotographic photoreceptor of the present invention may have other structural units as long as it has the structural unit represented by the above formula (1), or may be a copolymer with a structural unit consisting of a divalent carboxylic acid and a divalent organic residue other than those represented by the above formula (1).

[0016] The viscosity average molecular weight of the polyester resin is preferably 10,000 or more and 80,000 or less, and more preferably 40,000 or more and 70,000 or less.

[0017] The content ratio (mass ratio) of the charge transporting compound represented by the above formula (HTM1) to the polyester resin having the structural unit represented by the above formula (1) in the charge transporting layer is preferably 4:10 to 20:10, more preferably 6:10 to 12:10.

[0018] In addition, the charge transport layer of the present invention can improve durability (hereinafter also referred to as "wear resistance") without causing a decrease in sensitivity by containing silica particles as filler particles. The number average primary particle diameter of the filler particles is preferably 5 nm or more and 1000 nm or less. In order to improve the wear resistance of the electrophotographic photoreceptor, the number average primary particle diameter of the filler particles is more preferably 10 nm or more and 150 nm or less.

[0019] [Electrophotographic photoreceptor] The electrophotographic photoreceptor of the present invention has a support and a photosensitive layer formed on the support. Fig. 1 is a diagram showing an example of the layer structure of the electrophotographic photoreceptor. In Fig. 2, 101 is a support, 102 is an undercoat layer, 103 is a charge generating layer, 104 is a charge transport layer, and 105 is a photosensitive layer (laminated type photosensitive layer).

[0020] <Support> In the present invention, the support is preferably a conductive support having electrical conductivity. Examples of the conductive support include a support formed of a metal or alloy such as aluminum, iron, nickel, copper, or gold, and a support having a thin film of a metal such as aluminum, chromium, silver, or gold, a thin film of a conductive material such as indium oxide, tin oxide, or zinc oxide, or a thin film of a conductive ink containing silver nanowires formed on an insulating support such as polyester resin, polycarbonate resin, polyimide resin, or glass. In order to improve electrical properties and suppress interference fringes, the surface of the support may be subjected to electrochemical treatment such as anodization, wet honing, blasting, cutting, etc. The shape of the support may be a cylinder or a film.

[0021] <Conductive layer> In the present invention, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to cover unevenness and defects of the support and prevent interference fringes. The average thickness of the conductive layer is preferably 5 μm or more and 40 μm or less.

[0022] The conductive layer preferably contains conductive particles and a binder resin. Examples of the conductive particles include carbon black, metal particles, and metal oxide particles. Examples of the metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of the metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, it is preferable to use metal oxides as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide. When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof. Examples of the doped element or oxide thereof include phosphorus, aluminum, niobium, and tantalum. The conductive particles may have a laminated structure having a core particle and a coating layer that covers the core particle. Examples of the core particle include titanium oxide, barium sulfate, zinc oxide, etc. Examples of the coating layer include metal oxides such as tin oxide and titanium oxide. When a metal oxide is used as the conductive particles, the volume average particle size thereof is preferably 1 nm or more and 500 nm or less.

[0023] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0024] The average thickness of the conductive layer is preferably 1 μm or more and 50 μm or less. The conductive layer can be formed by preparing a coating solution for the conductive layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of the dispersion method for dispersing the conductive particles in the coating solution for the conductive layer include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0025] <Undercoat layer> An undercoat layer may be provided between the support and the charge generating layer. The undercoat layer contains a polyamide resin and titanium oxide particles. The polyamide resin is preferably a polyamide resin soluble in an alcohol-based solvent. For example, ternary (6-66-610) copolymer polyamide, quaternary (6-66-610-12) copolymer polyamide, N-methoxymethyl nylon, polymerized fatty acid polyamide, polymerized fatty acid polyamide block copolymer, copolymer polyamide having a diamine component, etc. are preferably used. From the viewpoint of suppressing charge accumulation, the titanium oxide particles preferably have a rutile or anatase crystal structure. The average primary particle size of the titanium oxide particles is preferably 10 nm or more and 100 nm or less. The titanium oxide particles may be treated with a silane coupling agent or the like.

[0026] The undercoat layer in the present invention may contain additives such as organic particles and a leveling agent in addition to the polyamide resin and titanium oxide particles for the purpose of improving the film-forming properties of the undercoat layer of the electrophotographic photoreceptor. The average thickness of the undercoat layer is preferably 0.5 μm or more and 5 μm or less. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying and / or curing it. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of the dispersion method for dispersing titanium oxide particles in the coating solution for the undercoat layer include ultrasonic dispersion, a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0027] <Charge generation layer> The charge generating layer preferably contains a charge generating material and a resin. The charge generating material used in the charge generating layer is preferably a phthalocyanine pigment, such as titanyl phthalocyanine, hydroxygallium phthalocyanine, or chlorogallium phthalocyanine, with titanyl phthalocyanine being more preferred. Examples of the binder resin used in the charge generating layer include resins (insulating resins) such as polyvinyl butyral resin, polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyvinylpyridine resin, urethane resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin. Organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinylpyrene can also be used. Only one type of binder resin may be used, or two or more types may be used in combination as a mixture or copolymer.

[0028] Examples of the solvent used in the charge generating layer coating liquid include toluene, xylene, tetralin, chlorobenzene, dichloromethane, chloroform, trichloroethylene, tetrachloroethylene, carbon tetrachloride, methyl acetate, ethyl acetate, propyl acetate, methyl formate, ethyl formate, acetone, methyl ethyl ketone, cyclohexanone, diethyl ether, dipropyl ether, propylene glycol monomethyl ether, dioxane, methylal, tetrahydrofuran, water, methanol, ethanol, n-propanol, isopropanol, butanol, methyl cellosolve, methoxypropanol, dimethylformamide, dimethylacetamide, dimethylsulfoxide, etc. The solvent may be used alone or in combination of one or more kinds.

[0029] The charge generation layer can be obtained by dispersing a phthalocyanine pigment as a charge generation material and, if necessary, a binder resin in a solvent to prepare a coating liquid for the charge generation layer, forming a coating film of the coating liquid for the charge generation layer, and drying the coating film. The coating liquid for the charge generating layer may be prepared by adding only the charge generating material to a solvent and dispersing the material, and then adding the binder resin, or by adding the charge generating material and the binder resin together to a solvent and dispersing the material. In the above dispersion, a media type dispersing machine such as a sand mill or a ball mill, a liquid collision type dispersing machine, an ultrasonic dispersing machine or the like can be used.

[0030] <Charge transport layer> In the electrophotographic photoreceptor of the present invention, the surface layer is a charge transport layer, which contains the above-mentioned polyester resin and charge transporting compound. The charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles. The average thickness of the charge transport layer is preferably from 5 μm to 50 μm, and more preferably from 8 μm to 40 μm. The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0031] <Process cartridge and electrophotographic apparatus> An example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member is shown in Figure 2. In Figure 2, reference numeral 1 denotes a cylindrical (drum-shaped) electrophotographic photosensitive member, which is driven to rotate around an axis 2 in the direction of the arrow at a predetermined peripheral speed (process speed). During the rotation process, the surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by a charging means 3. Next, the charged surface of the electrophotographic photoreceptor 1 is irradiated with exposure light 4 from an exposure means (not shown), and an electrostatic latent image corresponding to the target image information is formed. The image exposure light 4 is light that is intensity-modulated in response to a time-series electric digital image signal of the target image information, which is output from an exposure means such as a slit exposure or laser beam scanning exposure. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed (normal development or reversal development) with toner contained in the developing means 5, and a toner image is formed on the surface of the electrophotographic photoreceptor 1. The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to a transfer material 7 by transfer means 6. At this time, a bias voltage of a polarity opposite to that of the charge held by the toner is applied to the transfer means 6 from a bias power source (not shown). Furthermore, when the transfer material 7 is paper, the transfer material 7 is taken out from a paper feed section (not shown) and fed between the electrophotographic photoreceptor 1 and transfer means 6 in synchronization with the rotation of the electrophotographic photoreceptor 1.

[0032] The transfer material 7 onto which the toner image has been transferred from the electrophotographic photoreceptor 1 is separated from the surface of the electrophotographic photoreceptor 1, and then conveyed to a fixing means 8, where the toner image is fixed, and the image is printed out as an image-formed product (print, copy) outside the electrophotographic device. The surface of the electrophotographic photoreceptor 1 after the toner image has been transferred to the transfer material 7 is cleaned by a cleaning means 9 to remove adhesions such as toner (transfer residual toner). The transfer residual toner can also be directly removed by a developing device or the like using a cleanerless system that has been developed in recent years. Furthermore, the surface of the electrophotographic photoreceptor 1 is repeatedly used for image formation after being subjected to a charge removal process using pre-exposure light 10 from a pre-exposure means (not shown). Note that when the charging means 3 is a contact charging means using a charging roller or the like, the pre-exposure means is not necessarily required. In the present invention, a plurality of components among the components such as the electrophotographic photoreceptor 1, the charging means 3, the developing means 5, and the cleaning means 9 described above are housed in a container and supported as a unit to form a process cartridge. This process cartridge can be configured to be freely attached to and detached from the main body of the electrophotographic device. For example, at least one selected from the charging means 3, the developing means 5, and the cleaning means 9 is integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge. A process cartridge 11 can be formed that is detachably attached to the main body of the electrophotographic apparatus using a guide means 12 such as a rail of the main body of the electrophotographic apparatus. When the electrophotographic apparatus is a copying machine or a printer, the exposure light 4 may be reflected light or transmitted light from an original. Alternatively, the exposure light 4 may be light emitted by scanning a laser beam, driving an LED array, or driving a liquid crystal shutter array in accordance with a signal obtained by reading an original with a sensor and converting it into a signal. The electrophotographic photoreceptor 1 of the present invention can be widely used in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, FAX machines, liquid crystal printers, and laser plate making.

[0033] <Materials used in the Examples and Comparative Examples> As materials for producing a photoreceptor, the following charge generating substance, charge transporting compound, binder resin, and filler resin were prepared.

[0034] [Charge generating material] As titanyl phthalocyanine crystals, we prepared Y-type titanyl phthalocyanine (CGM1), which has a strong peak at 27.2° with a Bragg angle of 2θ±0.2° in CuKα characteristic X-ray diffraction, and crystalline hydroxygallium phthalocyanine (CGM2), which has strong peaks at 7.4° and 28.1° with a Bragg angle of 2θ±0.2° in CuKα characteristic X-ray diffraction.

[0035] [Charge transport compound] The above-mentioned charge transporting compound (HTM1) was prepared. In addition, charge transporting compounds (HTM2) to (HTM6) were also prepared. [ka] [ka] [ka] [ka] [ka]

[0036] [Binder resin] The polyester resin used in the present invention may be synthesized by an ester exchange method between a dicarboxylic acid ester and a compound having a hydroxyl group, or may be synthesized by a polymerization reaction between a divalent acid halide such as a dicarboxylic acid halide and a compound having a hydroxyl group such as a bisphenol. From the viewpoint of controllability of the molecular weight of the obtained product, the synthesis by the latter synthesis method is preferred.

[0037] (Polyester resin (1-1)) As a synthesis example, a method for synthesizing a polyester resin represented by the following (1-1) will be described below. A dicarboxylic acid chloride having a structure represented by the following formula (DC-1) was dissolved in dichloromethane to prepare an acid chloride solution. Separately from this acid chloride solution, bisphenol having the structure represented by the following formula (BP-1) was dissolved in a 10% aqueous sodium hydroxide solution, to which tributylbenzylammonium chloride was added as a polymerization catalyst and stirred to prepare a bisphenol solution. Next, the acid chloride solution was added to the bisphenol solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours with stirring while maintaining the reaction temperature at 25°C or less. Thereafter, acetic acid was added to terminate the polymerization reaction, and washing with water was repeated until the aqueous layer became neutral. After washing, the polymer was dropped into stirred methanol to precipitate the polymer, which was then vacuum dried to obtain a polyarylate resin represented by formula (1-1). The viscosity average molecular weight of the resulting polyarylate resin represented by formula (1-1) was 46,500. [ka] [ka] [ka]

[0038] (Polyester resins (1-2) to (1-24)) The structures of the polyester resins used in the present invention are shown below, and Table 1 shows the viscosity average molecular weights of the polyester resins. [ka] [ka] [ka] [ka] [ka]

change

change

change

change

change

change

change

change

change

change

change

change

change

change

change

change

change

change

[0039] [Table 1]

[0040] (Polycarbonate resin (2-1)) The following polycarbonate resins were prepared: Mitsubishi Gas Chemical Co., Ltd. "Iupilon Z400" (viscosity average molecular weight 40,000)

[0041] [Filler particles] The following filler particles (filler particles 1) to (filler particles 3) were prepared. AEROSIL is a registered trademark. Each filler particle was surface-treated with HDMS hexamethylsilazane. (Filler particles 1) "AEROSIL (registered trademark) RX300" manufactured by Nippon Aerosil Co., Ltd. Number average primary particle size: 7 nm (Filler particles 2) "AEROSIL (registered trademark) RX200" manufactured by Nippon Aerosil Co., Ltd. Number average primary particle size: 12 nm (Filler particles 3) "AEROSIL (registered trademark) RX50" manufactured by Nippon Aerosil Co., Ltd. Number average primary particle size: 40 nm

[0042] <Example> The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples in any way as long as the gist of the present invention is not exceeded. The thickness of each layer of the electrophotographic photoreceptor in the examples and comparative examples was measured, except for the charge generating layer, by a method using an eddy current film thickness meter (Fischerscope, manufactured by Fisher Instruments) or a method of converting the specific gravity from the mass per unit area. The film thickness of the charge generating layer was measured by converting the Macbeth density value of the photoreceptor using a calibration curve previously obtained from the Macbeth density value measured by pressing a spectrodensitometer (product name: X-Rite504 / 508, manufactured by X-Rite) against the surface of the photoreceptor and the film thickness measured by observing a cross-sectional SEM image.

[0043] [Example 1] <Undercoat layer> Surface-treated titanium oxide (number average primary particle diameter 10 nm) was prepared. Titanium oxide was surface-treated using alumina and silica, and the surface-treated titanium oxide was further surface-treated using methylhydrogenpolysiloxane while wet-dispersing. Next, 2 parts by mass of the surface-treated titanium oxide, 1 part by mass of polyamide resin ("Amilan CM8000" manufactured by Toray Industries, Inc., a tetrapolymer polyamide resin of polyamide 6, polyamide 12, polyamide 66 and polyamide 610), 10 parts by mass of methanol, 1 part by mass of butanol and 1 part by mass of toluene were mixed for 5 hours using a bead mill to obtain a coating liquid for an undercoat layer. Thereafter, the obtained coating liquid for an undercoat layer was dip-coated on a conductive support to form a coating film, and the coating film was thermally dried at 130°C for 30 minutes to form an undercoat layer with a film thickness of 1.5 μm. A cylindrical support made of aluminum was used as the conductive support.

[0044] <Charge generation layer> A Y-type titanyl phthalocyanine (CGM1) (1.5 parts by mass) as a charge generating material and a polyvinyl acetal resin ("S-LEC BX-5" manufactured by Sekisui Chemical Co., Ltd.) (1 part by mass) were added to a solvent containing propylene glycol monomethyl ether (40 parts by mass) and tetrahydrofuran (40 parts by mass). These materials and the solvent were mixed for 12 hours using a bead mill to disperse the materials in the solvent, and a coating liquid for a charge generating layer was prepared. The obtained coating liquid for a charge generating layer was dip-coated on the undercoat layer to form a coating film, and the coating film was heated and dried at a temperature of 100°C for 10 minutes to form a charge generating layer having a film thickness of 0.25 μm.

[0045] <Charge transport layer> A coating liquid for a charge transport layer was prepared by mixing 10 parts by mass of (HTM1) as a charge transporting compound and 10 parts by mass of polyester resin (1-1) as a binder resin with a solvent containing 150 parts by mass of tetrahydrofuran and 50 parts by mass of toluene. The obtained coating liquid for a charge transport layer was dip-coated on a charge generating layer to form a coating film, and the coating film was dried by heating at a temperature of 120° C. for 30 minutes to form a charge transport layer having a thickness of 30 μm.

[0046] [Examples 2 to 20, Comparative Examples 1 to 24] An electrophotographic photoreceptor was produced by changing the type of charge generation material in the charge generation layer, the type of charge transport compound in the charge transport layer, the type of binder resin, the type of filler particles, and the content of the charge transport compound relative to the content of the binder resin from the above [Example 1] as shown in the following Table 2. In addition, the content of the filler in the charge transport layer was produced so as to have a mass ratio of 5% relative to the total mass of the binder resin.

[0047] <Evaluation> The electrophotographic photoreceptors prepared as above were subjected to the following evaluations. The evaluation results are shown in Table 2. [Evaluation of wear resistance] The evaluation machine used to evaluate the wear resistance was a color copier (Samsung's "X4300LX"). Using the evaluation machine, 10,000 images were printed on the photoconductor at a temperature of 15°C and a relative humidity of 10%RH. The amount of wear of the charge transport layer was calculated from the difference in the photoconductor film thickness before and after repeated image printing. [Evaluation of electrical characteristics] The initial sensitivity of the photoreceptor was evaluated by the following method. Under an environment of a temperature of 25° C. and a relative humidity of 50% RH, the surface of the photoreceptor was charged to −600 V using a drum sensitivity tester (manufactured by Gentec Co., Ltd.). Then, using a bandpass filter, the photoreceptor was irradiated with white light from a halogen lamp to monochromatic light (wavelength 780 nm, light quantity on the surface of the electrophotographic photoreceptor 0.35 μJ / cm 2 ). 2 The surface potential of the photoconductor was measured 50 milliseconds after the start of irradiation.

[0048] [Table 2]

[0049] The disclosure of this embodiment includes the following configuration. [Configuration 1] An electrophotographic photoreceptor having a support, a charge generating layer formed on the support, and a charge transport layer formed on the charge generating layer, the surface layer being the charge transport layer, The charge transport layer comprises: A polyester resin having a structural unit represented by the following formula (1): Contains a charge transporting compound represented by the following formula (HTM1): 1. An electrophotographic photoreceptor comprising: [ka] X 1 represents a divalent group represented by formula (1A), formula (1B), formula (1C), formula (1D), or formula (1E). [ka] [ka] [ka] [ka] [ka] [ka] [Configuration 2] 2. The electrophotographic photoreceptor according to claim 1, wherein the content of the charge transport compound in the charge transport layer is 60% by weight or more and 120% by weight or less based on the content of the polyester resin. [Configuration 3] 3. The electrophotographic photoreceptor according to Configuration 1 or 2, wherein the structural unit represented by the formula (1) is contained in a mass ratio of 50% to 100% based on the total structural units of the polyester resin. [Configuration 4] 4. The electrophotographic photoreceptor according to any one of configurations 1 to 3, wherein the charge generating material in the charge generating layer is titanyl phthalocyanine. [Configuration 5] In the polyester resin, X in the structural unit represented by formula (1) 1 is represented by the formula (1A), the formula (1B), the formula (1C), or the formula (1D). [Configuration 6] 5. The electrophotographic photoreceptor according to any one of Configurations 1 to 4, wherein the charge transport layer contains silica particles as filler particles. [Configuration 7] A process cartridge integrally supports the electrophotographic photosensitive member according to any one of configurations 1 to 6 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to a main body of an electrophotographic apparatus. [Configuration 8] An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of configurations 1 to 6, a charging unit, an exposing unit, a developing unit, and a transferring unit. [Explanation of symbols]

[0050] 101: Conductive substrate 102: Undercoat layer 103: Charge generating layer 104: Charge transport layer 105: Photosensitive layer 1: Electrophotographic photoreceptor 2: Axis 3: Charging means 4: Image exposure light 5: Developing method 6: Transfer method 7: Transfer material 8: Image fixing means 9: Cleaning means 10: Pre-exposure light 11: Process cartridge 12: Guidance means

Claims

1. An electrophotographic photoreceptor having a support, a charge generating layer formed on the support, and a charge transporting layer formed on the charge generating layer, the charge transporting layer being a surface layer, The charge transport layer comprises: A polyester resin having a structural unit represented by the following formula (1): The charge transporting compound represented by the following formula (HTM1) is contained.

1. An electrophotographic photoreceptor comprising: 【Chemistry 1】 [X １ represents a divalent group represented by the following formula (1A), formula (1B), formula (1C), formula (1D), or formula (1E). 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】

2. 2 . The electrophotographic photoreceptor according to claim 1 , wherein the content of the charge transporting compound in the charge transport layer is from 60% by mass to 120% by mass with respect to the content of the polyester resin.

3. 2. The electrophotographic photoreceptor according to claim 1, wherein the structural unit represented by the formula (1) is contained in a mass ratio of 50% or more and 100% or less based on all structural units of the polyester resin.

4. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generating material in the charge generating layer is titanyl phthalocyanine.

5. In the polyester resin, X in the structural unit represented by the formula (1) １ The electrophotographic photoreceptor according to claim 1 , wherein the formula (1A), the formula (1B), the formula (1C), or the formula (1D) is represented by the formula (1A), the formula (1B), the formula (1C), or the formula (1D).

6. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer contains silica particles as filler particles.

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

8. 7. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1, a charging unit, an exposing unit, a developing unit, and a transferring unit.

Images