Electrophotographic photoreceptor, process cartridge, and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor that offers superior cleanability and durability, reduced residual potential, and suppressed occurrence of cracking.SOLUTION: An electrophotographic photoreceptor is provided, comprising a surface layer containing a binder resin and organic resin particles, where the binder resin has a specific structural unit and the organic resin particles are surface-treated with a specific compound.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] As an electrophotographic photoreceptor mounted in an electrophotographic apparatus, one containing an organic photoconductive substance (charge generating substance) is widely used. In recent years, in order to extend the life of the electrophotographic photoreceptor and improve the image quality during repeated use, an improvement in the mechanical durability (abrasion resistance) of the electrophotographic photoreceptor has been demanded. As a technique for improving the abrasion resistance of an electrophotographic photoreceptor, there is a method of reducing the friction between the surface layer of the electrophotographic photoreceptor and a contact member such as a cleaning blade by containing resin particles in the surface layer. Patent Document 1 discloses a technique of forming a surface layer using a dispersion liquid of fluorine atom-containing resin particles such as polytetrafluoroethylene resin particles as a coating liquid for the surface layer. Also, considering the impact on the environment, an electrophotographic photoreceptor composed of a material not containing fluorine atoms is desirable. Patent Documents 2 and 3 disclose techniques of reducing the friction between the surface layer and a contact member such as a cleaning blade by using resin particles not containing fluorine atoms.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the study by the present inventors, in the technologies disclosed in Patent Document 2 and Patent Document 3, while a surface layer excellent in cleaning property and wear resistance can be obtained, when fluorine atom-containing resin particles are used, deterioration of the residual potential and generation of cracks may occur.

[0005] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor capable of suppressing deterioration of the residual potential and generation of cracks while maintaining good cleaning property and wear resistance even in an electrophotographic photoreceptor containing no fluorine atoms.

Means for Solving the Problems

[0006] The above object is achieved by the following present invention. That is, according to one aspect of the present invention, there is provided an electrophotographic photoreceptor characterized in that a surface layer contains a binder resin having a structural unit represented by the following formula (A) and organic resin particles surface-treated with a compound represented by the following formula (C).

Chemical formula

Chemical formula

[0007] According to another aspect of the present disclosure, there is provided a process cartridge that integrally supports the electrophotographic photoreceptor and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachable from the electrophotographic apparatus main body.

[0008] According to another aspect of the present disclosure, there is provided an electrophotographic apparatus having the electrophotographic photoreceptor, as well as a charging means, an image exposure means, a developing means, and a transfer means.

Advantages of the Invention

[0009] According to one aspect of the present disclosure, it is possible to provide an electrophotographic photoreceptor that is excellent in cleaning property and durability, and in which the residual potential is reduced and cracks are suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail with reference to preferred embodiments. As a result of investigations by the present inventors, in a surface layer using a conventional configuration containing a binder resin and organic resin particles not containing fluorine, the interfacial state between the binder resin and the resin particles may be unstable compared to fluorine-containing resin particles. As a result, deterioration of the residual potential and generation of minute cracks may have occurred. The present inventors conducted investigations on the material composition to be contained in the surface layer in order to solve the above-described technical problems occurring in the prior art. As a result of the above investigations, it has been found that the above technical problems can be solved by using the electrophotographic photoreceptor according to the present invention described below.

[0012] That is, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a surface layer, wherein the surface layer contains a binder resin and organic resin particles, the binder resin contains a resin having a structural unit represented by the following formula (A) or (B), and the organic resin particles are surface-treated with a compound represented by the following formula (C) or (D). It is characterized by this.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0013] Regarding the mechanism by which the above technical problems in the prior art can be solved by the configuration of the present invention, the inventors of the present invention consider as follows. Depending on the compatibility such as the three-dimensional structure and electron localization of the binder resin and the organic resin particles, there may be partial differences in strength in the interaction at the interface between the binder resin and the resin particles. The inventors of the present invention speculate that due to the difference in the interfacial state, trap sites that cause residual potential may be formed, or uneven adhesion with the binder resin may occur, resulting in cracks. In the combination of the binder resin and the organic resin particles in the prior art, particularly on the surface of non-fluorine-based resin particles, the partial three-dimensional structure difference and electron localization for each structural unit tend to be large, and it is considered that the interfacial state difference due to the combination with the binder resin is likely to spread. Therefore, it is speculated that by surface-treating the organic resin particles with a compound as shown in, for example, formula (C), the interfacial state with the binder resin having a structure as shown in, for example, formula (A) can be made uniform, and the deterioration of the residual potential and the occurrence of cracks can be suppressed.

[0014] <Electrophotographic photoreceptor> FIG. 1 shows an example of the layer structure of the electrophotographic photoreceptor of the present invention. In FIG. 1, an undercoat layer 102, a charge generation layer 103, and a charge transport layer 104 are laminated on a support 101. The photosensitive layer may be composed of a laminated photosensitive layer having a charge generation layer and a charge transport layer, or may be composed of a single-layer photosensitive layer containing a charge generation substance and a charge transport substance. In the present invention, the outermost layer of the electrophotographic photoreceptor is defined as the surface layer. As a method for manufacturing the electrophotographic photoreceptor of the present invention, there is a method of preparing a coating solution for each layer, sequentially coating the desired layers, and drying them. At this time, examples of the coating method of the coating solution include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, and the like. Among these, dip coating is preferred from the viewpoints of efficiency and productivity. The support and each layer will be described below.

[0015] <Support> The support of the electrophotographic photoreceptor preferably has conductivity (conductive support). Examples of the shape of the support include a cylindrical shape, a belt shape, and a sheet shape. Among these, a cylindrical support is preferable. Also, the surface of the support may be subjected to electrochemical treatment such as anodic oxidation, blasting treatment, cutting treatment, or the like. As the material of the support, metals, resins, glass, etc. are preferable. Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferable. Also, it is preferable to impart conductivity to resins and glass by treatments such as mixing or coating with a conductive material.

[0016] <Conductive layer> A conductive layer may be provided on the support. By providing the conductive layer, it is possible to conceal scratches and unevenness on the surface of the support and to control the reflection of light on the support surface. The conductive layer preferably contains conductive particles and a binder resin. Examples of the material of the conductive particles include metal oxides, metals, carbon black, etc. Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of the metal include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc. Among these, it is preferable to use metal oxide particles as the conductive particles, and particularly, it is more preferable to use titanium oxide particles, tin oxide particles, and zinc oxide particles. When using metal oxide particles as the conductive particles, the surface of the metal oxide particles may be treated with a silane coupling agent or the like, or the metal oxide particles may be doped with elements such as phosphorus and aluminum or their oxides. Alternatively, the conductive particles may have a laminated structure including core particles and a coating layer that coats the particles. Examples of the core particles include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of the material of the coating layer include metal oxide particles such as tin oxide. When metal oxide particles are used as the conductive particles, the volume average particle diameter thereof is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0017] Examples of the binder resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. Further, the conductive layer may further contain a concealer such as silicone oil, resin particles, and titanium oxide. The conductive layer can be formed by preparing a coating solution for the conductive layer containing each of the above materials and a solvent, forming this coating film on a support, and drying it. Examples of the solvent used in the coating solution for the conductive layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon 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. The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0018] <Undercoat layer> In the present disclosure, an undercoat layer may be provided on the support or the conductive layer. By providing the undercoat layer, the interlayer adhesion function can be enhanced and a charge injection blocking function can be imparted. The undercoat layer preferably contains a binder resin. Further, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the binding resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include isocyanate group, blocked isocyanate group, methylol group, alkylated methylol group, epoxy group, metal alkoxide group, hydroxy group, amino group, carboxy group, thiol group, carboxylic anhydride group, and carbon-carbon double bond group.

[0019] In addition, for the purpose of enhancing the electrical properties, the undercoat layer may further contain an electron transport material, metal oxide particles, metal particles, a conductive polymer, etc. Among these, it is preferable to use an electron transport material and metal oxide particles. Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, boron-containing compounds, etc. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the above monomer having a polymerizable functional group to form the undercoat layer as a cured film. Examples of the metal oxide particles include particles of indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, zinc oxide, aluminum oxide, etc. Silicon dioxide particles can also be used. Examples of the metal particles include particles of gold, silver, aluminum, etc.

[0020] The metal oxide particles contained in the undercoat layer may be surface-treated using a surface treatment agent such as a silane coupling agent before use. As a method for surface-treating the metal oxide particles, a general method is used. For example, a dry method or a wet method can be mentioned. In the dry method, while stirring metal oxide particles in a mixer capable of high-speed stirring such as a Henschel mixer, an aqueous alcohol solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent is added, and after uniformly dispersing, drying is performed. In the wet method, metal oxide particles and a surface treatment agent are stirred in a solvent or dispersed using a sand mill or the like with glass beads or the like, and after dispersion, the solvent is removed by filtration or distillation under reduced pressure. After removing the solvent, it is preferably baked at 100°C or higher.

[0021] The undercoat layer may further contain additives, and for example, metal particles such as aluminum particles, conductive substance particles such as carbon black, charge transport substances, metal chelate compounds, known materials such as organometallic compounds can be contained. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing each of the above materials and a solvent, forming this coating film on a support or a conductive layer, and drying and / or curing it. Examples of the solvent used in the coating solution for the undercoat layer include organic solvents such as alcohol, sulfoxide, ketone, ether, ester, aliphatic halogenated hydrocarbon, and aromatic compounds. In the present disclosure, it is preferable to use alcohol-based and ketone-based solvents. Examples of the dispersion method for preparing the coating solution for the undercoat layer include methods using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, and a liquid collision type high-speed disperser. The average film thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, and particularly preferably 0.3 μm or more and 30 μm or less.

[0022] <Photosensitive layer> The photosensitive layer of the electrophotographic photoreceptor is mainly classified into (1) a laminated photosensitive layer and (2) a single-layer photosensitive layer. (1) The laminated photosensitive layer is a photosensitive layer having a charge generation layer containing a charge generating substance and a charge transport layer containing a charge transporting substance. (2) The single-layer photosensitive layer is a photosensitive layer containing both a charge generating substance and a charge transporting substance.

[0023] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generation layer and a charge transport layer.

[0024] (1-1) Charge generation layer The charge generation layer preferably contains a charge generating substance and a binder resin. Examples of the charge generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments, etc. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. The content of the charge generating substance in the charge generation layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generation layer. Examples of the binder resin include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, polyvinyl acetate resins, polyvinyl chloride resins, etc. Among these, polyvinyl butyral resin is more preferred. In addition, the charge generation layer may further contain additives such as antioxidants and ultraviolet absorbers. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, etc. can be mentioned. The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing each of the above materials and a solvent, forming this coating film on the undercoat layer, and drying it. Examples of the solvent used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like. The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0025] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a binder resin. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 55% by mass or less, based on the total mass of the charge transport layer.

[0026] Examples of the binder resin include polycarbonate resins, polyarylate resins, acrylic resins, polystyrene resins, and the like. Among these, thermoplastic resins are preferred, and particularly, polycarbonate resins and polyarylate resins are preferred. The content ratio (mass ratio) of the charge transport material to the binder resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0027] In addition, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, and lubricants. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, boron nitride particles, fluororesin particles, and the like can be mentioned. The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing each of the above materials and a solvent, forming this coating film on the charge generation layer, and drying it. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Among these solvents, ether solvents or aromatic hydrocarbon solvents are preferred. The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, and particularly preferably 35 μm or more and 50 μm or less.

[0028] (2) Single-layer type photosensitive layer The single-layer type photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating substance, a charge transporting substance, a binder resin, and a solvent, forming this coating film on the undercoat layer, and drying it. Examples of the charge generating substance, charge transporting substance, and binder resin are the same as those exemplified in the above “(1) Laminated type photosensitive layer”. The average film thickness of the single-layer type photosensitive layer is preferably 5 μm or more and 50 μm or less, and particularly preferably 35 μm or more and 50 μm or less.

[0029] <Surface layer> In the present invention, the layer on the outermost surface of the electrophotographic photoreceptor is defined as the surface layer. In the case of the electrophotographic photoreceptor having the above-described laminated type photosensitive layer, the charge transport layer is the surface layer. Also, in the case of the electrophotographic photoreceptor having the above-described single-layer type photosensitive layer, the photosensitive layer is the surface layer. The average film thickness of the surface layer is preferably 5 μm or more and 50 μm or less, and particularly preferably 35 μm or more and 50 μm or less. The surface layer of the present invention contains a binder resin having a unit structure represented by at least the following formula (A) or (B), and organic resin particles surface-treated with a compound represented by the following formula (C) or (D).

Chemical formula

Chemical formula

Chemical formula

[0030] [Binder resin] The surface layer of the electrophotographic photoreceptor of the present disclosure contains a binder resin having a unit structure represented by the above formula (A) or (B). Examples of the binder resin having these structures include polycarbonate resins and polyarylate resins. From the viewpoint of sufficiently exhibiting the effects of the present invention, a binder resin having a structural unit represented by the following formula (F) or (G) is particularly preferred. [Chemical formula] [Chemical formula] In the above formula (F), R 301 ~R 304 each independently represents a hydrogen atom or a methyl group. Y 2 represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. In the above formula (G), R 401 ~R 404 each independently represents a hydrogen atom or a methyl group.

[0031] Examples of the structural unit represented by formula (A) include the following structures.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0032] Examples of the structural unit represented by formula (B) include the following structures.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0033] [Organic resin particles] The surface layer of the electrophotographic photoreceptor of the present invention contains organic resin particles. The organic resin particles are surface-treated with a compound represented by the formula (C) or (D). Examples of the compound represented by the formula (C) include methyltrimethoxysilane, dimethyldimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, methyltrichlorosilane, hexyltrichlorosilane, and the like. Examples of the compound represented by the formula (D) include hexamethyldisilazane, 1,3-di-n-octyltetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1,3-dimethyl-1,1,3,3-tetraphenyldisilazane, and the like.

[0034] Examples of the resin contained in the organic resin particles used in the present invention include acrylic resin, styrene-acrylic resin, silicone resin, melamine resin, guanamine resin, and the like. It is also preferable to use particles containing a plurality of the above resins. Among the above, from the viewpoint of fully exerting the effects of the present invention, a resin having a unit structure represented by the following formula (E) is more preferable. [Chemical formula] In the above formula (E), R 1 represents a hydrogen atom or a methyl group. R 2 represents an alkyl group which may have a substituent.

[0035] In the present invention, from the viewpoints of the cleaning property and durability improvement of the surface layer, the content of the organic resin particles in the surface layer is preferably 1% by mass or more based on the total weight of the surface layer. Further, from the viewpoints of suppressing the residual potential and suppressing cracks, it is preferably 30% by mass or less based on the total weight of the surface layer. That is, the content of the organic resin particles in the surface layer is preferably 1% by mass or more and 30% by mass or less based on the total mass of the surface layer.

[0036] The organic resin particles used in the present invention are surface-treated with the compound represented by the formula (C) or (D). From the viewpoints of suppressing the residual potential and suppressing crack generation, among the compounds of the formula (C), those having an alkyl group with 6 to 12 carbon atoms are particularly preferably used.

[0037] In the elemental ratio of the surface layer, the silicon content derived from the compound used for the surface treatment is preferably 0.003 atomic% or more based on all the atoms in the surface layer excluding hydrogen atoms from the viewpoints of suppressing the residual potential and suppressing crack generation. Further, from the viewpoint of suppressing the residual potential, it is preferably 0.3 atomic% or less based on all the atoms in the surface layer excluding hydrogen atoms. That is, the content of the silicon atoms derived from the compound represented by the formula (C) or (D) in the surface layer is preferably 0.003 atomic% or more and 0.3 atomic% or less based on all the atoms (excluding hydrogen atoms) in the surface layer.

[0038] (Method for measuring silicon content) The elemental analysis of the surface layer is measured as follows using X-ray photoelectron spectroscopy (XPS). As the measurement sample, a surface layer piece cut out to 10 mm square is set on an XPS dedicated platen. Then, using the following XPS apparatus, the X-ray irradiation location and the sputtering location by GCIB (gas cluster ion beam) irradiation are set in the above sample part. Apparatus used: PHI5000VersaProbeII manufactured by ULVAC-PHI, Inc. Irradiation ray: Al-Kα ray Beam diameter: 100 μ Output: 25 W 15 kV Photoelectron capture angle: 45° PassEnergy: 58.70 eV Stepsize: 0.125 eV XPS Peaks: Si2p, N1s, C1s, O1s Measurement Range: 300 μm × 200 μm The values measured under the above conditions were taken as Si1 (atomic %). Furthermore, under the following sputtering conditions, sputtering was performed from the outermost surface to a depth of 40 nm in the surface layer, and the values measured under the above measurement conditions were taken as Si2 (atomic %). GUN Type: GCIB (Gas Cluster Ion Beam) Sputter Setting: 10 kV Regarding the position at a depth of 40 nm, the sputter rate (rate of depth with respect to time) was measured in advance, the sputter time corresponding to 40 nm was calculated, and sputtering was performed for the calculated time so that sputtering was performed up to a depth of 40 nm.

[0039] In the cross-sectional observation of the surface layer, for the organic resin particles, the arithmetic mean of the major axis diameters of the primary particles measured from the secondary electron image by a scanning electron microscope (average primary particle diameter) is preferably 10 nm or more and 300 nm or less from the viewpoints of improving dispersibility and suppressing the residual potential. The average primary particle diameter of the organic resin particles can be measured and calculated by the following method. (Measurement Method of Average Primary Particle Diameter) The average particle diameter of the organic resin particles is measured as follows using a field emission scanning electron microscope (FE-SEM). The organic resin particles are attached to a commercially available carbon conductive tape, and the organic resin particles not attached to the conductive tape are removed with compressed air, and platinum evaporation is performed. The evaporated organic resin particles were observed using an FE-SEM (S-4700) manufactured by Hitachi High-Technologies Corporation. The measurement conditions of the FE-SEM are as follows. Acceleration Voltage: 2 kV WD: 5 mm Magnification: 20,000 times Number of Pixels: 1280 pixels vertically and 960 pixels horizontally (size per pixel: 5 nm) From the obtained image, the Feret diameter of 100 particles was determined using ImageJ (open-source software manufactured by the National Institutes of Health (NIH) in the United States), and the average value was calculated and used as the average particle diameter. The organic resin particles of the present disclosure may be used alone or in combination of two or more.

[0040] <Charge transport material> The surface layer of the electrophotographic photoreceptor of the present disclosure may contain a charge transport material. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds are preferred. The charge transport material may be used alone or in combination of a plurality.

[0041] <Process cartridge, electrophotographic apparatus> The electrophotographic photoreceptor of the present disclosure may be one of the components of a process cartridge or an electrophotographic apparatus. The process cartridge integrally supports the electrophotographic photoreceptor described so far and at least one means selected from the group consisting of a charging means, a developing means, a transferring means, and a cleaning means, and is detachable from the electrophotographic apparatus main body. Further, the electrophotographic apparatus is characterized by having the electrophotographic photoreceptor, a charging means, an exposure means, a developing means, and a transferring means described so far.

[0042] Fig. 2 shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photoreceptor. The cylindrical (drum-shaped) electrophotographic photoreceptor 1 is rotationally driven about the axis 2 in the direction of the arrow at a predetermined peripheral speed (process speed). The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by the charging means 3 during the rotation process. In FIG. 2, a roller charging method using a roller-type charging member is shown, but charging methods such as a corona charging method, a proximity charging method, and an injection charging method may be employed. The surface of the charged 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 exposure light 4 is light whose intensity is modulated corresponding to the time-series electrical digital image signal of the target image information, and is output from an image exposure means such as slit exposure or laser beam scanning exposure, for example. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed (normal development or reversal development) with toner accommodated 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 the transfer means 6. At this time, a bias voltage having a polarity opposite to the charge held by the toner is applied to the transfer means 6 from a bias power supply (not shown). When the transfer material 7 is paper, the transfer material 7 is taken out from a paper feeding unit (not shown) and fed between the electrophotographic photoreceptor 1 and the transfer means 6 in synchronization with the rotation of the electrophotographic photoreceptor 1. The transfer material 7 from which the toner image has been transferred from the electrophotographic photoreceptor 1 is separated from the surface of the electrophotographic photoreceptor 1 and conveyed to the fixing means 8, and is printed out of the electrophotographic apparatus as an image formation (print, copy) by receiving the fixing process of the toner image. The electrophotographic apparatus may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. Alternatively, a so-called cleanerless system in which the above deposits are removed by a developing means or the like without separately providing a cleaning means may be used. In the present disclosure, among the components selected from the above electrophotographic photoreceptor 1, charging means 3, developing means 5, cleaning means 9, etc., a plurality of components can be housed in a container and integrally supported to form a process cartridge. Further, it can be configured to be detachable from the electrophotographic apparatus main body. For example, it can be configured as follows.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 photoreceptor 1 and made into a cartridge. Using guiding means 12 such as rails of the electrophotographic apparatus main body, it can be made into a process cartridge 11 that is detachable from the electrophotographic apparatus main body. The electrophotographic apparatus may have a discharging mechanism for discharging the surface of the electrophotographic photoreceptor 1 by pre-exposure light 10 from a pre-exposure means (not shown). Further, guiding means 12 such as rails may be provided for attaching and detaching the process cartridge 11 of the present disclosure to and from the electrophotographic apparatus main body. The electrophotographic apparatus of the present disclosure is characterized by having the electrophotographic photoreceptor 1 and at least one means selected from the group consisting of the charging means 3, the exposure means, the developing means 5, and the transfer means 6.

[0043] The electrophotographic photoreceptor of the present disclosure can be used in a laser beam printer, an LED printer, a copying machine, a facsimile machine, and a multi-functional machine thereof.

Example

[0044] Hereinafter, the present invention will be described in more detail using examples and comparative examples, but it is not limited thereto. In the description of the following examples, "parts" means based on mass unless otherwise specified.

[0045] <Surface treatment of organic resin particles> Using the compound represented by the formula (C) or (D), the surface of the organic resin particles was treated by the following methods respectively.

[0046] (Particle A1) 5 parts of polymethyl methacrylate particles with an average primary particle diameter of 150 nm, 15 parts of pure water, 15 parts of hexane, and 10 parts of methanol were added to a glass flask equipped with a stirrer, a constant temperature bath, and a thermometer, and the temperature was raised to 50 °C while stirring. Then, 1 part of dodecyltrimethoxysilane was added and stirred for 4 hours while maintaining 50 °C. Thereafter, the mixture was centrifuged, the separated precipitate was washed with ethanol, and dried for 4 hours under a reduced pressure state of a temperature of 50 °C and 1000 Pa or less to obtain surface-treated organic resin particles A1.

[0047] (Particles A2 to A16, C1 to C5) In the treatment of Particle A1, except that the surface treatment agent, particle type, stirring time, and particle diameter were appropriately changed as shown in Table 1, Particles A2 to A16 and C1 to C5 were obtained in the same manner as Particle A1.

[0048] (Particle B1) 5 parts of polymethyl methacrylate particles with an average primary particle diameter of 150 nm and 50 parts of hexane were added to a glass flask equipped with a stirrer, a constant temperature bath, and a thermometer, and the temperature was raised to 50 °C while stirring. Then, 1 part of hexamethyldisilazane was added, and the mixture was stirred for 4 hours while maintaining the temperature at 50 °C. Thereafter, the mixed solution was centrifuged, the separated precipitate was washed with ethanol, and dried for 4 hours under a reduced pressure state of 50 °C and 1000 Pa or less to obtain surface-treated organic resin particles B1.

[0049] (Particles B2 to B9, D1 to D2) In the treatment of Particle B1, except that the particle type, stirring time, and particle diameter were appropriately changed as shown in Table 1, Particles B2 to B9 and D1 to D2 were obtained in the same manner as Particle B1.

[0050]

Table 1

[0051] 〔Example 1〕 (Fabrication of electrophotographic photoreceptor) (Support) As the support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) processed by cutting was used. Ultrasonic cleaning was performed in a cleaning solution containing a detergent (trade name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water. Subsequently, after flushing the cleaning solution away, ultrasonic cleaning was further performed in pure water for degreasing treatment, and this was used as the support.

[0052] (Undercoat layer) Zinc oxide particles (average particle diameter: 70 nm, specific surface area value: 15 m 2 / g) 60 parts were stirred and mixed with 500 parts of tetrahydrofuran, and 0.75 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto, followed by stirring for 2 hours. Thereafter, tetrahydrofuran was distilled off under reduced pressure, and the mixture was dried by heating at 120°C for 3 hours to obtain surface-treated zinc oxide particles. Subsequently, 25 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 22.5 parts of blocked isocyanate (trade name: Sumidur BL-3173, manufactured by Sumitomo Bayer Urethane Co., Ltd.) as polyols were dissolved in 142 parts of methyl ethyl ketone. To this solution, 100 parts of the surface-treated zinc oxide particles and 1 part of anthraquinone were added, and the mixture was dispersed using a sand mill with 1-mm diameter glass beads for 5 hours. After the dispersion treatment, 0.008 part of dioctyltin dilaurate and 6.5 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicones Co., Ltd.) were added and stirred to prepare a coating solution for the undercoat layer. The obtained coating solution for the undercoat layer was dip-coated onto the above support to form a coating film, and the coating film was dried at 190°C for 24 minutes to form an undercoat layer having a film thickness of 20 μm.

[0053] (Charge generation layer) Next, 15 parts of chlorogallium phthalocyanine crystals having strong diffraction peaks at at least 7.4°, 16.6°, 25.5°, and 28.3° of the Bragg angle (2θ ± 0.2°) with respect to CuKα characteristic X-rays, 10 parts of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide Co., Ltd.), and 300 parts of n-butyl alcohol were mixed, and the mixture was dispersed using a sand mill with 1-mm diameter glass beads for 4 hours to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was dip-coated onto the above undercoat layer, and the obtained coating film was dried at 150°C for 5 minutes to form a charge generation layer having a film thickness of 0.2 μm.

[0054] (Charge transport layer) Next, 20 parts of the aforementioned particle A1 and 50 parts of tetrahydrofuran were stirred and mixed while maintaining the liquid temperature at 20°C for 48 hours to obtain a preparation liquid A. Next, 40 parts of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine, 20 parts of the compound represented by the following formula (CT-1), 70 parts of a resin having a repeating structure represented by the following formula (G-1) (viscosity average molecular weight 40,000), and 2.0 parts of 2,6-di-t-butyl-4-methylphenol as an antioxidant were mixed, and 250 parts of tetrahydrofuran was mixed and dissolved to obtain a preparation liquid B.

Chemical formula

Chemical formula

[0055] 〔Examples 2 to 34, Comparative Examples 1 to 7〕 In the formation of the charge transport layer, an electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the type of particles, the addition amount of particles, and the type of binder resin were changed as shown in Table 2. Here, (F-1) is a binder resin having a repeating structure in which R 301 ~R 304 in the above formula (F) is a methyl group and Y 2 is a p-phenylene group. Also, (A-2) is such that R 101 and R 104 in the above formula (A) are methyl groups, R 102 and R 103 are hydrogen groups, and X1 is a dimethylmethylene group, Y 1 is a binder resin having a repeating structure in which is a p-phenylene group. Further, (B-2) is a binder resin having the following repeating structure.

Chemical formula

[0056]

Table 2

[0057] <Evaluation of electrophotographic photoreceptor> The electrophotographic photoreceptors prepared in Examples 1 to 34 and Comparative Examples 1 to 7 were evaluated as follows.

[0058] 〔Evaluation apparatus 1-1〕 The electrophotographic photoreceptors prepared in Examples 1 to 34 and Comparative Examples 1 to 7 were mounted on an imageRUNNER ADVANCE DX C3835F (trade name), a copier manufactured by Canon Inc., for evaluation. Specifically, the evaluation apparatus was installed in an environment of a temperature of 23°C and a relative humidity of 50%RH. The prepared electrophotographic photoreceptor was mounted on a process cartridge for magenta color, and then mounted on the station of the magenta process cartridge for evaluation.

[0059] 〔Evaluation apparatus 1-2〕 The electrophotographic photoreceptors prepared in Examples 1 to 34 and Comparative Examples 1 to 7 were mounted on a modified version of an imageRUNNER ADVANCE DX C3835F (trade name), a copier manufactured by Canon Inc., for evaluation. Specifically, the evaluation apparatus was installed in an environment of a temperature of 23°C and a relative humidity of 50%RH. The prepared electrophotographic photoreceptor was mounted on a process cartridge for magenta color, and then mounted on the station of the magenta process cartridge for evaluation. The surface potential of the electrophotographic photoreceptor was measured by removing the developing cartridge from the above evaluation apparatus and inserting a potential measurement device therein. The potential measurement device is configured by arranging a potential measurement probe (trade name: model 6000B-8, manufactured by Trek Japan Co., Ltd.) at the developing position of the developing cartridge. The position of the potential measurement probe with respect to the electrophotographic photoreceptor is at the center in the bus bar direction of the electrophotographic photoreceptor, and the gap from the surface of the electrophotographic photoreceptor is 3 mm. Further, the potential at the central portion of the electrophotographic photoreceptor was measured using a surface potentiometer (trade name: model 344, manufactured by Trek Japan Co., Ltd.).

[0060] (Evaluation of cracks) The evaluation of cracks was carried out using the above evaluation apparatus 1-1. The cartridge with the electrophotographic photoreceptor attached was mounted on the evaluation apparatus, and a character image with a printing rate of 1% in monochrome was repeatedly formed 100,000 times using A4-sized plain paper. Thereafter, the electrophotographic photoreceptor was removed, and 10 sample pieces of 5×5 mm were cut out at a position about 180 mm from the upper end of the photoreceptor, and the occurrence state of cracks appearing on the surface was observed using FE-SEM (S-4700) manufactured by Hitachi High-Technologies Corporation. The measurement conditions of FE-SEM are as follows. Acceleration voltage: 2 kV WD: 5 mm Magnification: 10,000 times Number of pixels: 1280 pixels vertically and 960 pixels horizontally (size per pixel: 10 nm) Under these conditions, 10 sample pieces were observed, and the crack evaluation was performed by calculating the average total crack length per field of view from the average values of the number and size of the observed cracks. The results are shown in Table 3.

[0061] (Residual potential evaluation) The evaluation of the residual potential was performed by measuring the residual potential on the surface of the electrophotographic photoreceptor using the above evaluation apparatus 1-2. The applied bias was set so that the dark potential of the non-exposed portion of the electrophotographic photoreceptor was -600 V, and the light amount of the laser beam was 0.313 μJ / cm 2It was set to be so. After repeating the exposure equivalent to A3 size five times, the potential of the first round immediately after pre-exposure and charge elimination was measured and used as the residual potential. The results are shown in Table 3.

[0062] (Evaluation of durability) The evaluation of durability was carried out using the above-described evaluation apparatus 1-1. The cartridge equipped with the electrophotographic photoreceptor was attached to the evaluation apparatus, and a character image with a printing rate of 1% in monochrome was repeatedly formed using A4-size plain paper. During the repeated image formation, the film thickness of the image and the surface layer of the electrophotographic photoreceptor was appropriately confirmed, and the number of sheets passed until the minimum film thickness at which good image output could be ensured was confirmed. The results are shown in Table 3.

[0063] [Table 3]

[0064] The disclosure of this embodiment includes the following configurations. (Configuration 1) An electrophotographic photoreceptor having a surface layer, wherein the surface layer contains a binder resin and organic resin particles, the binder resin contains a resin having a structural unit represented by the following formula (A) or (B), and the organic resin particles are surface-treated with a compound represented by the following formula (C) or (D). An electrophotographic photoreceptor characterized by the above. [Chemical formula] [Chemical formula] [Chemical formula] [Chemical formula] (In the above formula (A), R 101 ~R 104 each independently represents a hydrogen atom or a methyl group. X1 represents a methylene group, a cyclohexylidene group, an oxygen atom or a single bond which may have an alkyl group or a phenyl group as a substituent. Y 1 represents an m-phenylene group, a p-phenylene group or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. In the above formula (B), R 201 ~R 204 each independently represents a hydrogen atom or a methyl group. X 2 represents a methylene group, a cyclohexylidene group, an oxygen atom or a single bond which may have an alkyl group or a phenyl group as a substituent. In the above formula (C), R 11 ~R 14 each independently represents an alkyl group, a phenyl group, an alkoxy group or a halogen atom. However, at least one of R 11 ~R 14 is an alkoxy group or a halogen atom. In the above formula (D), R 21 ~R 26 each independently represents an alkyl group or a phenyl group.) (Constitution 2) The electrophotographic photoreceptor according to Constitution 1, wherein the content of the organic resin particles in the surface layer is 1% by mass or more and 30% by mass or less based on the total mass of the surface layer. (Constitution 3) The electrophotographic photoreceptor according to Constitution 1 or 2, wherein the average primary particle diameter, which is the arithmetic mean of the major axis diameters of the primary particles of the organic resin particles in the surface layer, is 10 nm or more and 300 nm or less. (Constitution 4) The electrophotographic photoreceptor according to any one of Constitutions 1 to 3, wherein the content of the organic resin particles in the surface layer is 1% by mass or more and 30% by mass or less based on the total mass of the surface layer, and the average primary particle diameter, which is the arithmetic mean of the major axis diameters of the primary particles of the organic resin particles in the surface layer, is 10 nm or more and 300 nm or less. (Constitution 5) In the surface layer, the content of silicon atoms derived from the compound represented by the formula (C) or (D) is 0.003 atomic % or more and 0.3 atomic % or less with respect to all atoms (excluding hydrogen atoms) in the surface layer. The electrophotographic photoreceptor according to any one of Constitutions 1 to 4. (Constitution 6) In the surface layer, the organic resin particles have a structural unit represented by the following formula (E). The electrophotographic photoreceptor according to any one of Constitutions 1 to 5. [Chemical formula] (In the above formula (E), R 1 represents a hydrogen atom or a methyl group. R 2 represents an alkyl group which may have a substituent.) (Constitution 7) At least one of R 11 to R 14 in the formula (C) is an alkyl group having 6 to 12 carbon atoms. The electrophotographic photoreceptor according to any one of Constitutions 1 to 6. (Constitution 8) In the surface layer, the binder resin has a structural unit represented by the following formula (F) or (G). The electrophotographic photoreceptor according to any one of Constitutions 1 to 7. [Chemical formula] [Chemical formula] (In the above formula (F), R 301 to R 304 each independently represent a hydrogen atom or a methyl group. Y 2 represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom.) In the above formula (G), R 401 to R 404 each independently represent a hydrogen atom or a methyl group.) (Constitution 9) An electrophotographic photoreceptor according to any one of Configurations 1 to 8, and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, which are integrally supported and detachable from the main body of the electrophotographic apparatus. This is a feature of the process cartridge. (Configuration 10) An electrophotographic apparatus comprising an electrophotographic photoreceptor according to any one of Configurations 1 to 8, and a charging means, an image exposure means, a developing means, and a transfer means.

Explanation of Signs

[0065] 101 Substrate 102 Undercoat layer 103 Charge generation layer 104 Charge transport layer 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guide means

Claims

1. An electrophotographic photoreceptor having a surface layer, wherein the surface layer contains a binder resin and organic resin particles, the binder resin contains a resin having a structural unit represented by the following formula (A) or (B), and the organic resin particles are surface-treated with a compound represented by the following formula (C) or (D). An electrophotographic photoreceptor characterized by the above. 【Chemical 1】 【Chemical 2】 [Chemical Formula 3] 【Chemical 4】 (In the above formula (A), R １０１ ~R １０４ each independently represents a hydrogen atom or a methyl group. X １ represents a methylene group, a cyclohexylidene group, an oxygen atom or a single bond which may have an alkyl group or a phenyl group as a substituent. Y １ represents an m-phenylene group, a p-phenylene group or a divalent group in which two p-phenylene groups are bonded via an oxygen atom.) In the above formula (B), R ２０１ ~R ２０４ each independently represents a hydrogen atom or a methyl group. X ２ represents a methylene group, a cyclohexylidene group, an oxygen atom or a single bond which may have an alkyl group or a phenyl group as a substituent. In the above formula (C), R １１ ~R １４ each independently represents an alkyl group, a phenyl group, an alkoxy group or a halogen atom. However, R １１ ~R １４ At least one of them is an alkoxy group or a halogen atom. In the above formula (D), R ２１ ~R ２６ each independently represents an alkyl group or a phenyl group.).

2. The electrophotographic photoreceptor according to claim 1, wherein the content of the organic resin particles in the surface layer is 1% by mass or more and 30% by mass or less based on the total mass of the surface layer.

3. The electrophotographic photoreceptor according to claim 1, wherein the average primary particle diameter, which is the arithmetic mean of the major axis lengths of the primary particles of the organic resin particles in the surface layer, is 10 nm or more and 300 nm or less.

4. The electrophotographic photoreceptor according to claim 1, wherein the content of the organic resin particles in the surface layer is 1% by mass or more and 30% by mass or less based on the total mass of the surface layer, and the average primary particle diameter, which is the arithmetic mean of the major axis lengths of the primary particles of the organic resin particles in the surface layer, is 10 nm or more and 300 nm or less.

5. The electrophotographic photoreceptor according to claim 1, wherein the content of silicon atoms derived from the compound represented by the formula (C) or (D) in the surface layer is 0.003 atomic% or more and 0.3 atomic% or less based on all atoms (excluding hydrogen atoms) in the surface layer.

6. The electrophotographic photoreceptor according to claim 1, wherein the organic resin particles in the surface layer have a structural unit represented by the following formula (E). 【Chemical Formula 5】 (In the above formula (E), R １ represents a hydrogen atom or a methyl group. R ２ represents an alkyl group which may have a substituent.)

7. R in the formula (C) above １１ ~R １４ The electrophotographic photoreceptor according to claim 1, wherein at least one of them is an alkyl group having 6 to 12 carbon atoms.

8. The electrophotographic photoreceptor according to claim 1, wherein the binder resin in the surface layer has a structural unit represented by the following formula (F) or (G). 【Chemical Formula 6】 【Chemical Formula 7】 (In the above formula (F), R ３０１ to R ３０４ each independently represents a hydrogen atom or a methyl group. Y ２ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom.) In the above formula (G), R ４０１ to R ４０４ each independently represents a hydrogen atom or a methyl group.)

9. A process cartridge, comprising: the electrophotographic photoreceptor according to any one of claims 1 to 8; and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, which are integrally supported and detachable from the main body of the electrophotographic apparatus.

10. An electrophotographic apparatus, comprising: the electrophotographic photoreceptor according to any one of claims 1 to 8; a charging means; an image exposure means; a developing means; and a transfer means.

Images