Electrophotographic device

Abstract

To provide an electrophotographic device that prevents the occurrence of image density unevenness (pattern memory) after repeated use in a high temperature and high humidity environment.SOLUTION: An electrophotographic device has: electrifying means for electrifying a surface of an electrophotographic photoreceptor; image exposure means for forming an electrostatic latent image on the surface of the electrophotographic photoreceptor; developing means for forming a toner image on the surface of the electrophotographic photoreceptor; transfer means for transferring the toner image from the surface of the electrophotographic photoreceptor to a transfer material; and cleaning means for removing a residual toner remaining on the surface of the electrophotographic photoreceptor. The electrophotographic photoreceptor has a surface layer containing an enamine compound represented by a specific formula, a binder resin, and silicon atom-containing particles. The silicon atom-containing particles are silica particles or silicone resin particles. The toner has toner particles containing a polyester resin having a polyethylene terephthalate segment.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic apparatus.

Background Art

[0002] In recent years, various requirements such as high speed, miniaturization, and energy saving have been imposed on electrophotographic apparatuses. For electrophotographic photoreceptors used in electrophotographic apparatuses, higher sensitivity corresponding to high speed is required. For example, Patent Document 1 describes a technique for providing a highly sensitive electrophotographic photoreceptor by using an enamine compound as a charge transport material. In addition, in order to realize an energy-saving electrophotographic apparatus, a technique for fixing toner at a low temperature has been proposed. Patent Document 2 describes a technique related to a toner having, as one of resin components, a polyester obtained by reacting polyethylene terephthalate, an alcohol component, and a carboxylic acid component.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the above Patent Documents 1 and 2 are used in combination, there is room for improvement in repeated use in a high-temperature and high-humidity environment. That is, a difference in light part potential occurs during electrostatic latent image formation of the electrophotographic photoreceptor between the portion where printing on the electrophotographic photoreceptor is repeated and the other portion, and image density unevenness (pattern memory) may occur. The present disclosure is directed to providing an electrophotographic apparatus in which the occurrence of image density unevenness (pattern memory) during repeated use in a high-temperature and high-humidity environment is suppressed.

Means for Solving the Problem

[0005] According to the present disclosure, charging means for charging the surface of an electrophotographic photoreceptor, image exposure means for irradiating the surface of the charged electrophotographic photoreceptor with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photoreceptor, developing means having toner and developing the electrostatic latent image with the toner to form a toner image on the surface of the electrophotographic photoreceptor, transfer means for transferring the toner image from the surface of the electrophotographic photoreceptor to a transfer material, cleaning means for removing residual toner remaining on the surface of the electrophotographic photoreceptor after transferring the toner image from the surface of the electrophotographic photoreceptor to the transfer material, An electrophotographic apparatus having the electrophotographic photoreceptor having a surface layer containing a compound represented by the following formula (A), a binder resin, and silicon atom-containing particles, the silicon atom-containing particles being silica particles or silicone resin particles, the toner having toner particles containing a polyester resin having a polyethylene terephthalate segment, An electrophotographic apparatus characterized by the above is provided.

Chemical formula

Advantages of the Invention

[0006] According to one aspect of the present disclosure, an electrophotographic apparatus can be provided in which the occurrence of image density unevenness (pattern memory) during repeated use in a high-temperature and high-humidity environment is suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] As a result of the studies by the present inventors, by containing the compound represented by the above formula (A), a binder resin, and silicon atom-containing particles in the surface layer of the electrophotographic photoreceptor, and having toner particles containing a polyester resin having a polyethylene terephthalate segment, it has been found that the occurrence of image density unevenness (pattern memory) during repeated use in a high-temperature and high-humidity environment can be suppressed.

[0009] Regarding the reason why the electrophotographic apparatus of the present disclosure is excellent in suppressing the occurrence of image density unevenness during repeated use in a high-temperature and high-humidity environment, the present inventors presume as follows. The compound represented by formula (A) is a kind of enamine compound and is known to be used in an electrophotographic photoreceptor as a high-sensitivity charge transport material, but it has the characteristic that its sensitivity easily changes due to humidity changes.

[0010] On the other hand, a toner having a polyethylene terephthalate segment has a higher polarity tendency compared to the polyester resin generally used for toners, so it tends to have a higher affinity for water. Therefore, when toner is present on the surface of the electrophotographic photoreceptor, the amount of moisture on the surface of the electrophotographic photoreceptor becomes higher than the amount of moisture in the air in the use environment. When the electrophotographic apparatus is used in a high-temperature and high-humidity environment, the influence becomes significant.

[0011] When forming an image using an electrophotographic photoreceptor containing an enamine compound represented by formula (A) in the surface layer and a toner containing a polyester resin having a polyethylene terephthalate segment in a high-temperature and high-humidity environment, since the amount of moisture present on the surface of the highly polar toner increases, the amount of moisture present on the surface of the electrophotographic photoreceptor in contact with the toner also increases. When outputting a solid black band image, since the amount of toner present on the surface of the electrophotographic photoreceptor increases, the influence of the increase in the amount of moisture on the surface of the electrophotographic photoreceptor also becomes greater. It is considered that the moisture on the surface of the electrophotographic photoreceptor affects the sensitivity of the charge generating substance, and a sensitivity difference occurs between the solid black band portion and the solid white band portion in the electrophotographic photoreceptor. When outputting another pattern image with such a sensitivity difference remaining, a density difference occurs in an image portion where a density difference is not necessary, and this density difference is considered to appear on the image as a pattern memory.

[0012] As a result of the study by the present inventors, it has been found that an electrophotographic apparatus with suppressed pattern memory can be obtained by incorporating silica particles or silicone resin particles as silicon atom-containing particles in the surface layer of the electrophotographic photoreceptor.

[0013] Regarding the reason why the electrophotographic apparatus of the present disclosure is excellent in the pattern memory suppression effect, the inventors of the present invention speculate as follows. The surface layer of the electrophotographic photoreceptor of the present disclosure contains silicon atom-containing particles and an enamine compound represented by the formula (A). In the surface layer of the electrophotographic photoreceptor, it is speculated that the silicon atom-containing particles intervening between the surface and the enamine compound suppress the influence of moisture reaching the enamine compound from the surface. When the influence of surface moisture on the enamine compound is reduced, the sensitivity change due to moisture becomes small, and it is speculated that pattern memory is suppressed. Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

[0014] <Electrophotographic photoreceptor> The electrophotographic photoreceptor included in the electrophotographic apparatus of the present invention is characterized by having a surface layer containing the compound represented by the above formula (A), a binder resin, and silicon atom-containing particles. FIG. 1 shows an example of the layer structure of the electrophotographic photoreceptor of the present disclosure. In FIG. 1, a laminated photosensitive layer in which an undercoat layer 102, a charge generation layer 103, and a charge transport layer 104 are laminated on a support 101 is configured. 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 disclosure, a method of preparing coating liquids for each layer described later, coating the desired layers in order, and drying them can be mentioned. At this time, examples of the coating method of the coating liquid 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 preferable from the viewpoints of efficiency and productivity. Hereinafter, each layer will be described.

[0015] <Support> The support of the electrophotographic photoreceptor preferably has conductivity (conductive support). Also, examples of the shape of the support include a cylindrical shape, a belt shape, a sheet shape, etc. Among these, a cylindrical support is preferable. Further, electrochemical treatment such as anodization, blasting treatment, cutting treatment, etc. may be performed on the surface of the support. As the material of the support, metals, resins, glasses, etc. are preferable. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, alloys thereof, etc. Among these, an aluminum support using aluminum is preferable. Also, it is preferable to impart conductivity to resins and glasses by treatments such as mixing or coating with a conductive material. On the surface of the conductive support, if necessary, within a range not affecting the image quality, surface treatments such as anodized film treatment, treatment with chemicals, hot water, etc., coloring treatment, and diffuse reflection treatment such as roughening the surface may be performed. Diffuse reflection treatment is particularly effective when using the photoreceptor according to the present invention in an electrophotographic process using a laser as an exposure light source. That is, in an electrophotographic process using a laser as an exposure light source, since the wavelengths of the laser light are uniform, the laser light reflected on the surface of the photoreceptor and the laser light reflected inside the photoreceptor interfere with each other, and interference fringes due to this interference may appear in the image and cause image defects. Therefore, by performing diffuse reflection treatment on the surface of the conductive support, it is possible to prevent image defects due to interference of laser light with uniform phase.

[0016] <Conductive layer> A conductive layer may be provided on the support. By providing a conductive layer, it is possible to conceal scratches and unevenness on the surface of the support and to control light reflection on the support surface. The conductive layer preferably contains conductive particles and a 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, and the like. Examples of the metal include aluminum, nickel, iron, chromium, copper, zinc, silver, and the like. Among these, it is preferable to use metal oxide particles as the conductive particles, and it is more preferable to use titanium oxide particles, tin oxide particles, or zinc oxide particles in particular. 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 an element such as phosphorus or aluminum or an oxide thereof. Further, the conductive particles may have a laminated structure including core particles and a coating layer covering the particles. Examples of the core particles include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of the coating layer include metal oxide particles such as tin oxide. When using metal oxide particles 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 resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, and the like. Further, the conductive layer may further contain a concealer such as silicone oil, resin particles, or 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, or a liquid collision type high-speed disperser. The 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 adhesion function between layers can be enhanced, and a charge injection blocking function can be imparted. The undercoat layer preferably contains a resin. Further, an undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the 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] Further, the undercoat layer may further contain an electron transport material, metal oxide particles, metal particles, a conductive polymer, etc. for the purpose of enhancing electrical properties. 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, and boron-containing compounds. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the above-mentioned monomer having a polymerizable functional group to form an undercoat layer as a cured film. Examples of the metal oxide particles include particles such as indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, zinc oxide, and aluminum oxide. Silicon dioxide particles can also be used. Examples of the metal particles include particles such as gold, silver, and aluminum.

[0020] The metal oxide particles contained in the undercoat layer may be surface-treated with 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 the 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, the metal oxide particles and the 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 an additive. For example, known materials such as metal particles such as aluminum particles, conductive substance particles such as carbon black, charge transport substances, metal chelate compounds, and 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 compound. In the present disclosure, it is preferable to use an alcohol-based or ketone-based solvent. Examples of the dispersion method for preparing the coating liquid 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 film thickness of the undercoat layer is preferably 0.1 μm or more and 30 μm or less, and particularly preferably 0.3 μm or more and 5 μm or less.

[0022] <Charge generation layer> The charge generation layer preferably contains a charge generating substance and a resin. Examples of the charge generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, titanyl phthalocyanine pigments, oxy titanium phthalocyanine pigments, chloro gallium phthalocyanine pigments, and hydroxy gallium 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, and 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 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, and polyvinyl chloride resins. Among these, polyvinyl butyral resin is more preferred. Further, the charge generation layer may further contain additives such as an antioxidant and an ultraviolet absorber. 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 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.

[0023] <Charge transport layer> The charge transport layer preferably contains a charge transport material, a binder material, and silicon atom-containing particles. The charge transport material of the present invention contains at least a compound represented by formula (A).

Chemical formula

[0024] Ar 1 and Ar 2 Examples of the aryl group which may have substituents of Ar and Ar include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 4-isopropylphenyl group, 3,4-dimethylphenyl group, 2-fluorophenyl group, 4-chlorophenyl group, 4-(2-fluoroethyl)phenyl group, 4-methoxyphenyl group, 2,4-dimethoxyphenyl group, 2-methyl-4-methoxyphenyl group, 2,5-dimethyl-4-methoxyphenyl group, 4-biphenylyl group, p-terphenyl group, 4-dimethylaminophenyl group, 4-trifluoromethylphenyl group, 1-naphthyl group, 2-naphthyl group, 2-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5-methyl-1-naphthyl group, 4-methoxy-1-naphthyl group, 6-methoxy-2-naphthyl group, 2-methyl-4-methoxy-1-naphthyl group, 9-anthryl group, 1-pyrenyl group, 4-(4-methyl-phenoxy)phenyl group, 4-(phenylthio)phenyl group, 2,5-dimethyl-4-(phenylthio)phenyl group, p-(phenylthio)phenyl group and p-styrylphenyl group, etc.

[0025] Ar 1 and Ar 2 Examples of the alkyl group which may have substituents of Ar and Ar include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, trifluoromethyl group, fluoromethyl group and 1-methoxyethyl group, etc.

[0026] Ar 1 and Ar 2 Examples of the monovalent heterocyclic group which may have substituents of Ar and Ar include 8-chromanyl group, furyl group, thienyl group, 5-methyl-2-furyl group, 5-methyl-2-thienyl group, 5-methyl-N-ethylcarbazol-4-yl group, thiazolyl group, benzofuryl group, benzothiophenyl group, N-methylindolyl group, benzothiazolyl group, benzoxazolyl group, etc.

[0027] Ar 1 and Ar 2 may be bonded to each other via an atom or an atomic group to form a ring structure. Specific examples of the bonding atom include an oxygen atom and a sulfur atom, and specific examples of the bonding atomic group include a divalent atomic group such as a nitrogen atom having an alkyl group, as well as divalent groups such as alkylene groups such as methylene, ethylene, and methylmethylene, unsaturated alkylene groups such as vinylene and propenylene, alkylene groups containing heteroatoms such as oxymethylene (chemical formula: -O-CH2-), and unsaturated alkylene groups containing heteroatoms such as thiovinylene (chemical formula: -S-CH=CH-).

[0028] a 1 ~a 6 Examples of the alkyl group which may have a substituent include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, a fluoromethyl group, and a 1-methoxyethyl group. a 1 ~a 6 Examples of the alkoxy group which may have a substituent include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group. a 1 ~a 6 Examples of the optionally substituted dialkylamino group include a dimethylamino group, a diethylamino group, and a diisopropylamino group. a 1 ~a 6 Examples of the aryl group which may have a substituent include a phenyl group, an o-tolyl group, a m-tolyl group, a p-tolyl group, and a 4-methoxyphenyl group. a 1 ~a 6 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0029] b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5Examples of the alkyl group which may have a substituent include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a trifluoromethyl group, a fluoromethyl group, and a 1-methoxyethyl group. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5 Examples of the alkoxy group which may have a substituent include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5 Examples of the optionally substituted dialkylamino group include a dimethylamino group, a diethylamino group, and a diisopropylamino group. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5 The aryl group which may have a substituent is Ar 1 , and Ar 2 The same can be mentioned. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5 An example of the optionally substituted aryloxy group is a 4-methylphenoxy group. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d 5 An example of the optionally substituted arylthio group is a phenylthio group. b 1 ~b 5 , c 1 ~c 5 and d 1 ~d5 Examples of the halogen atom in 5 include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0030] The compound represented by formula (A) is generally called an enamine compound. Specific examples of the compound represented by formula (A) of the present invention are shown in Table 1 below.

[0031] [Table 1]

[0032] As other charge transport materials in the charge transport layer, for example, polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, triarylamine compounds, resins having groups derived from these substances, etc. can be used in combination. 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, more preferably 30% by mass or more and 55% by mass or less, based on the total mass of the charge transport layer.

[0033] As the binder material, a thermoplastic resin (hereinafter also referred to as "resin") is used. Examples of the thermoplastic resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among these, polycarbonate resin and polyester resin are preferred. The content ratio (mass ratio) of the charge transport material to the resin is preferably 3:10 to 20:10, more preferably 5:10 to 12:10.

[0034] The silicon atom-containing particles are added for the purpose of suppressing the change in the sensitivity of the enamine compound due to moisture in the present invention described above. The silicon atom-containing particles in the present invention are silica particles or silicone resin. Among these, silica particles are preferred. Examples of commercially available silica particles that can be used in the present disclosure include, for example, product names of Nippon Aerosil Co., Ltd.: AEROSIL (registered trademark) 130, AEROSIL R972, AEROSIL R974, AEROSIL NY50, AEROSIL RX50; product names of Cabot Japan Ltd.: TS610, TS620, TS630; product name of Shin-Etsu Chemical Co., Ltd.: X-24-9163A; product names of Admatechs Co., Ltd.: SO-E1, SO-E2, SE100-GDT, SE100-SPT; product name of Nippon Steel Mining Co., Ltd.: Silanax. Examples of commercially available silicone resin particles that can be used in the present disclosure include, for example, silicone resin particles manufactured by Shin-Etsu Chemical Co., Ltd.: X-52-854, X-52-1621, KMP-590; silicone resin particles manufactured by Nikko Rika Co., Ltd.: MSP-N050, MSP-N080, etc. The content of the silicon atom-containing particles in the charge transport layer is preferably 1% by mass or more and 20% by mass or less based on the total mass of the charge transport layer. If it is 1% by mass or less, it is difficult to obtain the effects of the present invention. If it exceeds 20% by mass, the bright part potential of the exposed part will increase due to the increase in residual charge during repeated use. The mass ratio of the compound represented by formula (A) to the silicon atom-containing particles contained in the surface layer is preferably 3:1 to 20:1. The number average primary particle diameter of the silicon atom-containing particles contained in the charge transport layer is determined from the cross-section of the charge transport layer. Specifically, 50 silicon atom-containing particles in the cross-section of the surface layer are observed to obtain an image. Elliptical fitting is performed on the image to obtain the longest diameter. The average of the 10 largest longest diameters obtained is taken as the average primary particle diameter of the silicon atom-containing particles. The number average primary particle diameter of the silicon atom-containing particles is preferably 1 nm or more and 500 nm or less, and more preferably 5 nm or more and 300 nm or less.

[0035] In addition, the charge transport layer may contain various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a leveling agent. Specifically, examples thereof include a hindered phenol compound, a hindered amine compound, a sulfur compound, a phosphorus compound, a benzophenone compound, a siloxane-modified resin, a silicone oil, polystyrene resin particles, polyethylene resin particles, and boron nitride particles. The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing 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 preferable. The film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 15 μm or more and 35 μm or less.

[0036] [Toner and Developer] The toner used in the electrophotographic apparatus of the present disclosure is a toner having toner particles containing a polyester resin having a polyethylene terephthalate segment. Hereinafter, the toner according to the present disclosure will be described.

[0037] [Polyester Resin Having Polyethylene Terephthalate Segment] The components constituting the polyester resin having a polyethylene terephthalate segment include a polyethylene terephthalate segment, a dihydric or higher alcohol monomer component, and an acid monomer component such as a dihydric or higher carboxylic acid, a dihydric or higher carboxylic anhydride, and a dihydric or higher carboxylic acid ester.

[0038] [Polyethylene Terephthalate Segment] The polyethylene terephthalate segment of the present disclosure has a structure in which the structural unit of polyethylene terephthalate (C 10 H8O4) is repeated. The polyethylene terephthalate segment of the present disclosure can be produced by a conventional method through a condensation reaction or transesterification reaction of ethylene glycol with terephthalic acid, dimethyl terephthalate, etc. Further, recycled polyethylene terephthalate resin can also be used.

[0039] Furthermore, it is more preferable to use a toner as shown below because low-temperature fixability and scratch resistance can be improved. The toner preferably used in the present disclosure is a toner having toner particles containing a binder resin, wherein the binder resin contains an amorphous resin A and a crystalline polyester C, The amorphous resin A is the polyester resin, and as a structure forming a polyester skeleton, (i) the polyethylene terephthalate segment, and (ii) at least one structure selected from the group consisting of units represented by the following formulas (1) to (4),

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0040] Hereinafter, the reasons for the improvement in low-temperature fixability and scratch resistance will be explained. As a result of the study by the present inventors, it has been found that in a toner having the following characteristics, good low-temperature fixability is exhibited while improving scratch resistance. (i) It can flexibly deform the three-dimensional structure in the direction in which an external force is applied. (ii) When the external force is removed, it can return to the original three-dimensional structure. Such a toner can be achieved by having the above-described configuration.

[0041] The amorphous resin A has at least one structure selected from the group consisting of units represented by formulas (1) to (4), and the SP value of the amorphous resin A and the crystalline polyester C is controlled, so that it has an affinity for the crystalline polyester. Therefore, in the fixed image, the amorphous resin A is affected by the crystalline polyester C and becomes flexible. And this structure can flexibly deform the three-dimensional structure in the direction in which the external force is received without breaking the molecular chain in order to disperse the applied external force. Further, since the amorphous resin A contains a polyethylene terephthalate segment, it has a repeating structure of a condensate of terephthalic acid and ethylene glycol in the polyester skeleton. The structure derived from ethylene glycol in the polyethylene terephthalate segment has ester groups at a very close molecular distance of two carbon atoms because both ends of ethylene glycol are ester-reacted. Therefore, the amorphous resin A has ester groups localized in the resin. Also, the phosphorus compound in which three non-bonding electron pairs in the outermost shell have reacted also has a bonding point at a very close molecular distance. Therefore, the amorphous resin A can interact with the localized ester groups in the amorphous resin A around the phosphorus element of the phosphorus compound to form a three-dimensional crosslinked structure. By having this structure, when the applied external force is removed, it can return from the deformed state to the original three-dimensional structure. As described above, it is considered that by adopting the configuration of the present disclosure, excellent low-temperature fixability and scratch resistance can be obtained.

[0042] The amorphous resin A of the present disclosure has at least one structure selected from the group consisting of units represented by formulas (1) to (4) as a structure forming a polyester skeleton. The structure of the long-chain hydrocarbon group such as an alkyl group or an alkenyl group contained in the units represented by formulas (1) to (4) is a relatively low-polarity structure compared to the structure derived from ethylene glycol of the polyethylene terephthalate segment described above. Therefore, the structure of the long-chain hydrocarbon group such as an alkyl group or an alkenyl group contained in the units represented by formulas (1) to (4) becomes flexible by increasing the affinity with the crystalline polyester C. And this structure can flexibly deform the three-dimensional structure in the direction in which the external force is received without breaking the molecular chain in order to disperse the applied external force. As a result, excellent scratch resistance can be obtained by realizing an improvement in elastic deformation. Also, the SP A (cal / cm 3 ) 0.5 of the amorphous resin A and the SP C (cal / cm 3 ) 0.5 of the crystalline polyester C satisfy the above formula (C). When SP A -SP C satisfies the above formula (C), the amorphous resin A and the crystalline polyester C are likely to be compatible, so the crystalline polyester C can act on the structure having a long-chain hydrocarbon group such as an alkyl group or an alkenyl group of the amorphous resin A smoothly. Therefore, this structure becomes flexible by increasing the affinity with the crystalline polyester C. And the structure can flexibly deform the three-dimensional structure in the direction in which the external force is received without breaking the molecular chain in order to disperse the applied external force. As a result, excellent scratch resistance can be obtained by realizing an improvement in elastic deformation characteristics.

[0043] Furthermore, the toner of the present disclosure contains a phosphorus element derived from a phosphorus compound, and W P(ppm) satisfies the above formula (D). When the phosphorus element content in the toner satisfies the above formula (D), it indicates that there is a sufficient amount of phosphorus element that interacts with the localized ester groups in the amorphous resin A around the phosphorus element to form a three-dimensional crosslinked structure. That is, it is the minimum amount of phosphorus element that can flexibly change the three-dimensional structure in the direction of the external force received without breaking the molecular chain to disperse the given external force, and the maximum amount of phosphorus element that can ensure a certain plastic deformation to guarantee low-temperature fixability.

[0044] <Amorphous resin A> The amorphous resin A is a polyester resin and has the following (i) and (ii) as the structure forming the polyester backbone.

[0045] (i) Segments of polyethylene terephthalate (ii) At least one structure selected from the group consisting of units represented by formulas (1) to (4) The polyethylene terephthalate structure used in the amorphous resin A is obtained by polycondensing ethylene glycol and terephthalic acid.

[0046] And the synthesis of the polyester resin can be carried out in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and further, if necessary, in the presence of an esterification co-catalyst, a polymerization inhibitor, etc., preferably at a temperature of 180°C or higher and 250°C or lower.

[0047] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamineate. Among these, tin compounds such as tin(II) 2-ethylhexanoate are preferred. The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.0 part by mass or less, based on 100 parts by mass of the raw material monomers (alcohol component, carboxylic acid component, and PET). Examples of the esterification co-catalyst include gallic acid. The amount of the esterification co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the raw material monomers. Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the raw material monomers.

[0048] In the synthesis of the polyester resin, polyethylene terephthalate may be present from the start of the polycondensation reaction or added to the reaction system during the polycondensation reaction. In order for the polyethylene terephthalate segment to be incorporated into the main skeleton of the polyester in a somewhat blocky form, the addition timing of polyethylene terephthalate is preferably at a stage where the reaction rate of the alcohol component and the carboxylic acid component is 10% or less, more preferably 5% or less. Here, the reaction rate refers to the value of (mol of generated reaction water amount) / (mol of theoretical generated water amount)×100.

[0049] In addition, the polyethylene terephthalate segment contained in the amorphous resin A can use used polyethylene terephthalate (so-called recycled PET). Reusing polyethylene terephthalate is preferable from an environmental perspective.

[0050] Used PET is collected, and the collected PET is washed, sorted to prevent mixing with other materials or garbage, and after removing labels, etc., it is crushed into flakes or the like. The crushed material can be used as it is, or the crushed material can be kneaded and coarsely crushed before use. If chemicals adsorbed on the surface of the PET bottle cannot be sufficiently removed by normal washing, alkali washing may be carried out. When a part of the crushed material is hydrolyzed by alkali washing, in order to restore the reduced degree of polymerization, it is preferable to melt the washed crushed material and subject the pelletized product to solid-phase polymerization. The solid-phase polymerization step can be carried out by continuously performing solid-phase polymerization of the washed flakes or the flakes melt-extruded and pelletized in an inert gas such as nitrogen gas or rare gas at 180 to 245 °C, preferably 200 to 240 °C. Further, the washed crushed material may be depolymerized to decompose it into monomer units and then re-synthesized for use. Further, the recycled PET is not limited to the above-mentioned used PET, and fiber scraps or pellets of off-spec PET discharged from the factory may be used.

[0051] In addition, in order to incorporate at least one unit selected from the group consisting of the units represented by formulas (1) to (4) into the amorphous resin A, the following monomers can be used. 1,6-Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, hexadecanedioic acid, octadecanedioic acid, dodecenyl succinic acid, n-octyl succinic acid, isododecenyl succinic acid, dodecyl succinic acid, isooctenyl succinic acid, hexadecyl succinic acid, etc.

[0052] Among the units represented by formulas (1) to (4), the units represented by formulas (1) and (2) are preferable. The presence of an alkyl group or alkenyl group having 6 to 16 carbon atoms branched from the main chain of the polyester skeleton increases the affinity with the mold release agent and further enhances the dispersibility of the mold release agent.

[0053] In addition, as components for obtaining the amorphous resin A, in addition to the above-described structures and monomers, other polyhydric alcohols (alcohols having two or more hydroxyl groups), polyvalent carboxylic acids (carboxylic acids having two or more carboxyl groups), their acid anhydrides, or their lower alkyl esters may be used.

[0054] As the polyhydric alcohol monomers, the following polyhydric alcohol monomers can be used. As the dihydric alcohol component, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenols represented by the formula (X) and their derivatives;

Chemical formula

Chemical formula

[0055] As the alcohol component having three or more hydroxyl groups, for example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene may be mentioned. Among these, preferably, glycerol, trimethylolpropane, and pentaerythritol are used.

[0056] These divalent alcohols and polyhydric alcohols with three or more hydroxyl groups can be used alone or in combination.

[0057] Examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, azelaic acid, malonic acid, anhydrides of these acids, and lower alkyl esters thereof. Among these, maleic acid, fumaric acid, and terephthalic acid are preferably used.

[0058] Examples of the polyhydric carboxylic acid with three or more hydroxyl groups, its acid anhydride, or its lower alkyl ester include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylene carboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, Empol trimer acid, anhydrides of these acids, or lower alkyl esters thereof. Among these, 1,2,4-benzenetricarboxylic acid, that is, trimellitic acid or its derivatives, is preferably used because it is inexpensive and easy to control the reaction. These divalent carboxylic acids and polyhydric carboxylic acids with three or more hydroxyl groups can be used alone or in combination.

[0059] The method for producing the amorphous resin A is not particularly limited, and known methods can be used. For example, the aforementioned alcohol monomer and carboxylic acid monomer are charged simultaneously, and polymerized through an esterification reaction or transesterification reaction, and a condensation reaction to produce a polyester resin. The polymerization temperature is not particularly limited, but a range of 180°C or higher and 290°C or lower is preferable. When polymerizing the polyester unit, for example, polymerization catalysts such as titanium-based catalysts, tin-based catalysts, zinc acetate, antimony trioxide, and germanium dioxide can be used. In particular, the amorphous resin A is more preferably a polyester resin polymerized using a tin-based catalyst.

[0060] The amorphous resin A may be a polyester resin having a vinyl resin part. As a method for obtaining a polyester bonded with a vinyl resin, a method using a monomer component capable of reacting with both the vinyl resin and the polyester unit is preferable. Such monomers are preferably monomers having an unsaturated double bond and a carboxy group or a hydroxy group. Examples include unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, and itaconic acid or their anhydrides, and acrylic acid or methacrylic acid esters.

[0061] Also, from the viewpoint of low-temperature fixability and the like, it is preferable that the peak molecular weight of the amorphous resin A is 3500 or more and 20000 or less. The glass transition temperature is preferably 40°C to 70°C.

[0062] In addition to the amorphous resin A, various resins conventionally known as binder resins can be used in combination as the amorphous resin. Examples of such resins include phenol resins, natural resin-modified phenol resins, natural resin-modified malein resins, acrylic resins, methacrylic resins, polyvinyl acetate resins, silicone resins, polyester resins, polyurethanes, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, petroleum resins, and the like.

[0063] <Crystalline polyester C> As monomers used for the polyester unit of the crystalline polyester C used in the toner of the present disclosure, a polyhydric alcohol (a dihydric or trihydric or higher alcohol), a polyvalent carboxylic acid (a dihydric or trihydric or higher carboxylic acid), its acid anhydride or its lower alkyl ester are used.

[0064] As the polyhydric alcohol monomer used for the polyester unit of the crystalline polyester C, the following polyhydric alcohol monomers can be used.

[0065] The polyhydric alcohol monomer is not particularly limited, but is preferably a chain (more preferably a straight-chain) aliphatic diol. For example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-butadiene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, neopentyl glycol can be mentioned. Among these, in particular, straight-chain aliphatic α,ω-dials such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol are preferably exemplified.

[0066] In the present disclosure, polyhydric alcohol monomers other than the above polyhydric alcohols can also be used. Examples of the dihydric alcohol monomers among the polyhydric alcohol monomers include aromatic alcohols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A; and 1,4-cyclohexanedimethanol. Examples of the polyhydric alcohol monomers having three or more hydroxyl groups among the polyhydric alcohol monomers include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; and aliphatic alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin element, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.

[0067] As the polycarboxylic acid monomer used in the polyester unit of the crystalline polyester C, the following polycarboxylic acid monomers can be used.

[0068] The polycarboxylic acid monomer is not particularly limited, but is preferably a chain (more preferably linear) aliphatic dicarboxylic acid. Specific examples include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid, and also include acid anhydrides thereof or those obtained by hydrolyzing lower alkyl esters.

[0069] In the present disclosure, polycarboxylic acids other than the above polycarboxylic acid monomers can also be used. Among other polycarboxylic acid monomers, examples of the divalent carboxylic acid include aromatic carboxylic acids such as isophthalic acid and terephthalic acid; aliphatic carboxylic acids such as n-dodecyl succinic acid and n-dodecenyl succinic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and their acid anhydrides or lower alkyl esters are also included. Among other carboxylic acid monomers, examples of the polycarboxylic acid having three or more valences include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and pyromellitic acid, and aliphatic carboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, and 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, and their derivatives such as acid anhydrides or lower alkyl esters are also included.

[0070] Further, the crystalline polyester C is preferably a modified crystalline polyester having a structure in which the hydroxy group at the main chain terminal is end-capped with an aliphatic monocarboxylic acid having 16 to 31 carbon atoms, or a modified crystalline polyester having a structure in which the carboxy group at the main chain terminal is end-capped with an aliphatic monoalcohol having 15 to 30 carbon atoms.

[0071] Examples of the aliphatic monocarboxylic acid monomer having 16 to 31 carbon atoms include palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), nonadecylic acid, arachidic acid (eicosanoic acid), heneicosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, octacosanoic acid, and triacontanoic acid.

[0072] Examples of aliphatic monoalcohols having 15 to 30 carbon atoms include cetyl alcohol, palmitic alcohol (hexadecanol), margaric alcohol (heptadecanol), stearyl alcohol (octadecanol), nonadecanol, arachidyl alcohol (icosanol), heneicosanol, behenyl alcohol, lignoceryl alcohol, cerotic alcohol, 1-heptacosanol, montanyl alcohol, 1-nonacosanol, and myristyl alcohol.

[0073] Crystalline polyester C can be produced according to a conventional polyester synthesis method. For example, after subjecting the above-described carboxylic acid monomer and alcohol monomer to an esterification reaction or a transesterification reaction, a crystalline polyester can be obtained by carrying out a polycondensation reaction under reduced pressure or while introducing nitrogen gas according to a conventional method. Thereafter, by further adding the above aliphatic compound and carrying out an esterification reaction, the desired crystalline polyester C can be obtained.

[0074] The above esterification or transesterification reaction can be carried out using a conventional esterification catalyst or transesterification catalyst such as sulfuric acid, titanium butoxide, dibutyltin oxide, manganese acetate, magnesium acetate, etc. as necessary.

[0075] Also, the above polycondensation reaction can be carried out using a known catalyst such as a conventional polymerization catalyst, for example, titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide, etc. The polymerization temperature and the amount of catalyst are not particularly limited and may be appropriately determined.

[0076] In the esterification or transesterification reaction or polycondensation reaction, a method of charging all monomers at once may be used to increase the strength of the obtained crystalline polyester C. Also, a method such as reacting a divalent monomer first and then adding and reacting a trivalent or higher monomer to reduce low molecular weight components may be used.

[0077] The melting point of the crystalline polyester C is preferably from 70°C to 110°C, more preferably from 80°C to 100°C, which is preferable from the viewpoint of low-temperature fixability. In the toner of the present disclosure, the crystalline polyester C is preferably used in an amount of 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the amorphous resin, from the viewpoints of low-temperature fixability, rub resistance, and charge retention property in a high-temperature and high-humidity environment.

[0078] <Phosphorus compound> Examples of the phosphorus compound used in the toner of the present disclosure include trisodium phosphate, trimethyl phosphate, triethyl phosphate, tri-2-ethylhexyl phosphate, tris(isopropylphenyl) phosphate, triphenyl phosphate, tributyl phosphate, trimethyl phosphite, tributyl phosphite, triphenyl phosphite, and the like. Among them, trivalent phosphorus compounds that easily form three-dimensional crosslinks are preferable.

[0079] Content W of phosphorus element P is as described above. Further, in order to form a three-dimensional crosslinked structure, it is preferable that the used polyethylene terephthalate (so-called recycled PET) is used because the blocks of polyethylene terephthalate are easily formed, so that ester groups with close molecular distances gather more, and a strong three-dimensional crosslinked structure can be formed. This structure can return to its original three-dimensional structure when the applied external force is removed.

[0080] <Release agent> The toner particles may contain wax as a release agent. Examples of the wax include polyethylene wax, polypropylene wax, polypropylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, carnauba wax, rice wax, candelilla wax, montan wax, and the like.

[0081] <Colorant> The toner may contain a colorant. Examples of the colorant include known organic pigments, oil dyes, or magnetic materials. Examples of the colorant include, for example, carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine-B-based, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, benzidine yellow, monoazo-based dyes and pigments, disazo-based dyes and pigments, and the like.

[0082] <Charge control agent> The toner particles may contain a charge control agent as needed. By blending a charge control agent, the charge characteristics can be stabilized, and it becomes possible to control the optimum triboelectric charge amount according to the developing system. As the charge control agent, known ones can be used, but in particular, a metal compound of an aromatic carboxylic acid that is colorless, has a fast charge speed of the toner, and can stably hold a certain charge amount is preferable.

[0083] Examples of the negative charge control agent include metal compounds of salicylic acid, metal compounds of naphthoic acid, metal compounds of dicarboxylic acid, polymer-type compounds having sulfonic acid or carboxylic acid in the side chain, polymer-type compounds having sulfonate or sulfonic acid esterified products in the side chain, polymer-type compounds having carboxylate or carboxylic acid esterified products in the side chain, boron compounds, urea compounds, silicon compounds, and calixarenes.

[0084] <Inorganic fine particles> The toner may contain inorganic fine particles as needed.

[0085] The inorganic fine particles may be internally added to the toner particles or may be mixed with the toner particles as an external additive. Examples of the inorganic fine particles include fine particles such as silica fine particles, titanium oxide fine particles, alumina fine particles, or their complex oxide fine particles. Among the inorganic fine particles, silica fine particles and titanium oxide fine particles are preferable for improving fluidity and charge uniformity. The inorganic fine particles are preferably hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil, or a mixture thereof.

[0086] <External additive> As the external additive, in addition to the above-mentioned inorganic fine particles, organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles may be used.

[0087] From the viewpoint of improving fluidity, the median diameter (D50) based on the number of external additives is preferably 10 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and still more preferably 90 nm or less.

[0088] The content of the external additive is preferably 0.1 part by mass to 10.0 parts by mass with respect to 100 parts by mass of the toner particles. Mixing of the toner particles and the external additive can be performed using a known mixer such as a Henschel mixer.

[0089] <Developer> The toner can be used as a one-component developer, but in order to further improve dot reproducibility and to supply a stable image over a long period of time, it is preferably mixed with a magnetic carrier and used as a two-component developer.

[0090] Examples of the magnetic carrier include iron oxide; metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, and rare earths, alloy particles thereof, oxide particles thereof; magnetic materials such as ferrite; a magnetic material dispersion resin carrier (so-called resin carrier) containing a magnetic material and a binder resin for holding the magnetic material in a dispersed state; etc., and generally known ones can be used.

[0091] <Method for Manufacturing Toner Particles> The method for manufacturing toner particles is not particularly limited, and known methods such as a pulverization method, a suspension polymerization method, a dissolution suspension method, an emulsion aggregation method, and a dispersion polymerization method can be used. Among them, from the viewpoint of controlling the wax on the toner particle surface, the pulverization method is preferable. That is, the toner particles are preferably pulverized toner particles. Hereinafter, the toner manufacturing procedure by the pulverization method will be described.

[0092] The pulverization method includes, for example, a raw material mixing step of mixing a crystalline polyester C, an amorphous resin A, a phosphorus compound, and other components such as other amorphous resins, waxes, colorants, and charge control agents as components constituting the toner particles as needed, a step of melt-kneading the mixed raw materials to obtain a resin composition, and a step of pulverizing the obtained resin composition to obtain toner particles.

[0093] In the raw material mixing step, as materials constituting the toner particles, for example, a binder resin, a wax, and other components such as a colorant and a charge control agent as needed are weighed and blended in predetermined amounts and mixed. Examples of the mixing device include a double cone mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a mechano hybrid (manufactured by Nippon Coke & Engineering Co., Ltd.).

[0094] Next, the mixed materials are melt-kneaded to disperse the materials in the binder resin. In the melt-kneading step, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. Due to the advantage of continuous production, single-screw or twin-screw extruders are the mainstream. For example, a KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by K.C.K. Co., Ltd.), a co-kneader (manufactured by Busse Co., Ltd.), and a Neidex (manufactured by Nippon Coke & Engineering Co., Ltd.) can be mentioned. Further, the resin composition obtained by melt-kneading may be rolled with a two-roll or the like and cooled with water or the like in a cooling step.

[0095] Next, the cooled resin composition is pulverized to a desired particle size in the pulverization step. In the pulverization step, first, it is roughly pulverized with a pulverizer such as a crusher, a hammer mill, or a feather mill. Then, it is finely pulverized with a fine pulverizer such as a cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), a super rotor (manufactured by Nisshin Engineering Co., Ltd.), a turbo mill (manufactured by Turbo Industry), or an air jet type.

[0096] Then, if necessary, it is classified using a classifier or a sieve such as an elbow jet of the inertial classification method (manufactured by Nippon Steel Mining Co., Ltd.), a turbo plex of the centrifugal classification method (manufactured by Hosokawa Micron Corporation), a TSP separator (manufactured by Hosokawa Micron Corporation), or a faculty (manufactured by Hosokawa Micron Corporation).

[0097] Then, if necessary, an external additive such as silica fine particles is externally added to the surface of the toner particles to obtain a toner. Examples of the apparatus for external addition treatment include mixing apparatuses such as a double con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, a mechano hybrid (manufactured by Nippon Coke & Engineering Co., Ltd.), and a nobilta (manufactured by Hosokawa Micron Corporation). The measurement methods for various physical properties will be described below.

[0098] (Separation method of each material from toner) Each material can be separated from the toner by utilizing the difference in solubility of each material contained in the toner in a solvent or GPC. Using the separated materials, the following various physical properties can be measured.

[0099] First separation: The toner is dissolved in methyl ethyl ketone (MEK) at 23°C to separate the soluble components (amorphous resin A, amorphous resin B (used in the examples, the same applies hereinafter), crystalline polyester C, phosphorus compound) and the insoluble components (wax, colorant, inorganic fine particles, etc.).

[0100] Second Separation: Dissolve the soluble components (amorphous resin A, amorphous resin B, crystalline polyester C, phosphorus compound) obtained in the first separation in tetrahydrofuran (THF) at 23°C, and separate the soluble components (amorphous resin A, amorphous resin B, phosphorus compound) from the insoluble component (crystalline polyester C).

[0101] Third Separation: Dissolve the insoluble components (wax, colorant, inorganic fine particles, etc.) obtained in the first separation in MEK at 100°C, and separate the soluble component (wax) from the insoluble components (colorant, inorganic fine particles, etc.).

[0102] Fourth Separation: Dissolve the soluble components (amorphous resin A, amorphous resin B, phosphorus compound) obtained in the second separation in tetrahydrofuran (THF) at 23°C, and separate amorphous resin A, amorphous resin B, and the phosphorus compound by preparative GPC.

[0103] <Method for Confirming the Attribution and Measuring the Content Ratio of Various Monomer Units in Amorphous Resin and Crystalline Polyester> The confirmation of the attribution and the measurement of the content ratio of various monomer units in the amorphous resin and the crystalline polyester are 1 performed by 1H-NMR under the following conditions.

[0104] Measuring apparatus: FT NMR apparatus JNM-EX400 (manufactured by JEOL Ltd.) Measuring frequency: 400 MHz Pulse condition: 5.0 μs Frequency range: 10500 Hz Number of integrations: 64 times Measuring temperature: 30°C Sample: Put 50 mg of the measurement sample into a sample tube with an inner diameter of 5 mm, add deuterated chloroform (CDCl3) as a solvent, and dissolve it in a constant temperature bath at 40°C for preparation.

[0105] Obtained 1 From the obtained 1H-NMR chart, identify the structures of various monomer units, and calculate the integral values S1, S2, S3, ··· S of the peaks attributed to each monomer unit n

[0106] ​ The content ratios of various monomer units are determined as follows using the above integral values S1, S2, S3, and S n Note that n1, n2, n3 ··· n n are the numbers of hydrogens in their respective monomer units.

[0107] Content ratio (mol%) of various monomer units = { (S n / n n ) / ((S1 / n1) + (S2 / n2) + (S3 / n3) ··· + (S n / n n ))} × 100 By changing the numerator term of the same operation, the content ratios (mol%) of various monomer units are calculated respectively. When a polymerizable monomer containing no hydrogen atom is used for various monomer units, 13 using 13C-NMR, the measurement nucleus is 13 13C, and the measurement is performed in single pulse mode, 1 and it is calculated in the same manner by 1H-NMR.

[0108] <Method for Calculating SP Value of Amorphous Resin and Crystalline Polyester> The SP values of the amorphous resin and the crystalline polyester are calculated according to the calculation method proposed by Fedors.

[0109] Specifically, the evaporation energy (Δei), molar volume (Δvi), and molar ratio (j) in the resin for each monomer unit are determined. Using these, the SP value is calculated from the following formula.

[0110] SP value (cal / cm 3 ) 0.5 = { (Σj × ΣΔei) / (Σj × ΣΔvi)} 0.5 As the evaporation energy (Δei) and molar volume (Δvi) of the atoms or atomic groups in the monomer unit, the values described in "polym.Eng.Sci., 14(2), 147 - 154(1974)" are used.

[0111] <Content W of Phosphorus Element in Toner PMeasurement method> Content W of phosphorus element in toner P (ppm) is measured using a multi - element simultaneous ICP emission spectrometer Vista - PRO (manufactured by Hitachi High - Technologies Corporation).

[0112] Sample: 50 mg Solvent: 6 mL of nitric acid Weigh the above and perform decomposition treatment using a microwave sample pretreatment device ETHOS UP (manufactured by Milestone General). Temperature: Heat up from 20°C to 230°C and hold at 230°C for 30 min After passing the decomposition solution through filter paper (5C), transfer it to a 50 mL volumetric flask and make up to 50 mL with ultrapure water. By measuring the aqueous solution in the volumetric flask with a multi - element simultaneous ICP emission spectrometer Vista - PRO under the following conditions, the content of phosphorus element in the toner can be quantified. The quantification of the content is calculated based on a calibration curve prepared using a standard sample of the element to be quantified.

[0113] Conditions: RF power 1.20 kW, Ar gas: Plasma flow 15.0 L / min, Auxiliary flow: 1.50 L / min, MFC: 1.50 L / min, Nebulizer flow: 0.90 L / min, Liquid delivery pump speed: 15 rpm, Measurement repetition: 3 times, Measurement time: 1.0 s

[0114] [Electrophotographic apparatus] Further, the electrophotographic apparatus of the present invention is characterized by having the electrophotographic photoreceptor, charging means, image exposure means, developing means, transfer means, and cleaning means described so far. Fig. 2 shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photoreceptor. 1 is a cylindrical electrophotographic photoreceptor, which is rotationally driven at a predetermined peripheral speed in the direction of the arrow around the axis 2. The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by the charging means 3. In the figure, although a roller charging method using a roller type charging member is shown, charging methods such as a corona charging method, a proximity charging method, and an injection charging method may also be employed. Image exposure light 4 is irradiated from an image exposure means (not shown) onto the charged surface of the electrophotographic photoreceptor 1, and an electrostatic latent image corresponding to the target image information is formed. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed 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. The transfer material 7 onto which the toner image has been transferred is conveyed to the fixing means 8, undergoes a fixing process of the toner image, and is printed out outside the electrophotographic apparatus. The electrophotographic apparatus has a cleaning means 9 for removing deposits such as residual toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. The electrophotographic apparatus may have a mechanism (not shown) for supplying a lubricant to the surface of the electrophotographic photoreceptor. 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, in order to attach and detach the process cartridge of the present invention to and from the electrophotographic apparatus main body, guiding means 12 such as rails may be provided. The electrophotographic photoreceptor of the present invention can be used in a laser beam printer, an LED printer, a copying machine, a facsimile machine, and a composite machine thereof.

Example

[0115] Hereinafter, the present invention will be described more specifically with reference to production examples and examples, but these do not limit the present invention. In the following formulations, the parts are all based on mass unless otherwise specified.

[0116] [Production Example of Electrophotographic Photoreceptor] <Production Example of Electrophotographic Photoreceptor 1> ·Support As a support (conductive support), an aluminum cylinder with a length of 357.5 mm and an outer diameter of 30 mm was prepared. · Formation of the undercoat layer 3 parts by mass of titanium oxide (trade name: TTO-55(D), manufactured by Ishihara Sangyo Co., Ltd.) and 2 parts by mass of copolymer polyamide (nylon) (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) were added to 25 parts by mass of methyl alcohol, and dispersed for 8 hours using a paint shaker to prepare a coating solution for the undercoat layer. The obtained coating solution for the undercoat layer was immersed in the conductive support and then pulled up, and the obtained coating film was dried at 100 °C for 20 minutes to form an undercoat layer with a film thickness of 1 μm on the conductive support. · Formation of the charge generation layer 1 part by mass of titanyl phthalocyanine having a strong peak at 27.2° of the Bragg angle 2θ ± 0.2° in CuKα characteristic X-ray diffraction as a charge generating substance and 1 part by mass of butyral resin (trade name: Esrec BM-2(Z), manufactured by Sekisui Chemical Co., Ltd.) as a binder were mixed with 98 parts by mass of methyl ethyl ketone, and dispersed for 8 hours using a paint shaker to prepare a coating solution for forming the charge generation layer. The obtained coating solution for forming the charge generation layer was applied to the surface of the previously provided undercoat layer in the same manner as in the case of forming the undercoat layer, and dried at 80 °C for 15 minutes to form a charge generation layer with a film thickness of 0.3 μm. · Formation of the charge transport layer (surface layer) 100 parts by mass of the compound represented by formula (A) (exemplary compound 2 shown in Table 1) as a charge transport substance, 90 parts by mass of polycarbonate resin (TS2050: manufactured by Teijin Chemicals Ltd.), and 10 parts by mass of silica particles (AEROSIL 130: manufactured by Nippon Aerosil Co., Ltd., number average primary particle diameter 16 nm) were mixed. After preparing a suspension using tetrahydrofuran as a solvent, it was stirred for 15 hours using a ball mill. The obtained mixture was subjected to 1Pass dispersion treatment using a particle dispersion device (model: M-110P, manufactured by Microfluidics Corp.) to prepare a coating solution for the charge transport layer. The obtained coating solution for the charge transport layer was applied onto the charge generation layer by the same dipping method as in the case of forming the undercoat layer, and the obtained coating film was dried at 130 °C for 1 hour to form a charge transport layer (surface layer) with a film thickness of 30 μm, thereby obtaining the electrophotographic photoreceptor 1 shown in FIG. 1.

[0117] <Production Example of Electrophotographic Photoreceptor 2> An electrophotographic photoreceptor 2 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were changed from 10 parts by mass to 5 parts by mass.

[0118] <Production Example of Electrophotographic Photoreceptor 3> An electrophotographic photoreceptor 3 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were changed from 10 parts by mass to 33 parts by mass.

[0119] <Production Example of Electrophotographic Photoreceptor 4> An electrophotographic photoreceptor 4 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were changed to AEROSIL 300 (manufactured by Nippon Aerosil Co., Ltd., number average primary particle diameter 7 nm).

[0120] <Production Example of Electrophotographic Photoreceptor 5> An electrophotographic photoreceptor 5 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were changed to SO-E1 (manufactured by Admatechs Co., Ltd., number average primary particle diameter 300 nm).

[0121] <Production Example of Electrophotographic Photoreceptor 6> An electrophotographic photoreceptor 5 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the compound represented by the formula (A) contained in the surface layer was changed from the exemplified compound 2 in Table 1 to the exemplified compound 1 in Table 1.

[0122] <Production Example of Electrophotographic Photoreceptor 7> An electrophotographic photoreceptor 2 was produced in the same manner as in the production example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were changed from 10 parts by mass to 3 parts by mass.

[0123] <Manufacturing Example of Electrophotographic Photoconductor 8> An electrophotographic photoconductor 8 was manufactured in the same manner as in the manufacturing example of electrophotographic photoconductor 1, except that the silica particles contained in the surface layer were changed to SO-E2 (manufactured by Admatechs Co., Ltd., number average primary particle diameter 500 nm).

[0124] <Manufacturing Example of Electrophotographic Photoconductor 9> An electrophotographic photoconductor 9 was manufactured in the same manner as in the manufacturing example of electrophotographic photoconductor 1, except that the exemplified compound 2 contained in the surface layer was changed from 100 parts by mass to 75 parts by mass, the polycarbonate resin was changed from 90 parts by mass to 140 parts by mass, and the silica particles were changed from 10 parts by mass to 25 parts by mass, and further 75 parts by mass of the bistriphenylamine compound represented by the following formula (B) was added.

Chemical formula

[0125] <Manufacturing Example of Electrophotographic Photoconductor 10> An electrophotographic photoconductor 10 was manufactured in the same manner as in the manufacturing example of electrophotographic photoconductor 1, except that the silica particles contained in the surface layer were changed from 10 parts by mass to 100 parts by mass.

[0126] <Manufacturing Example of Electrophotographic Photoconductor 11> An electrophotographic photoconductor 11 was manufactured in the same manner as in the manufacturing example of electrophotographic photoconductor 1, except that the silica particles contained in the surface layer were changed to silicone resin particles (X-52-854: manufactured by Shin-Etsu Chemical Co., Ltd., number average primary particle diameter 700 nm) and changed from 10 parts by mass to 3 parts by mass.

[0127] <Manufacturing Example of Electrophotographic Photoconductor 12> An electrophotographic photoconductor 12 was manufactured in the same manner as in the manufacturing example of electrophotographic photoconductor 1, except that the silica particles contained in the surface layer were changed to hollow silica particles (Silanax: manufactured by Nippon Steel Mining Co., Ltd., number average primary particle diameter 100 nm).

[0128] <Manufacturing Example of Electrophotographic Photoconductor 13> An electrophotographic photoreceptor 13 was manufactured in the same manner as the manufacturing example of the electrophotographic photoreceptor 1, except that the silica particles contained in the surface layer were not added. The electrophotographic photoreceptors 1 to 13 manufactured above are shown in Table 2.

[0129]

Table 2

[0130] [Production Example 1 of Toner] <Measurement Method of Softening Point of Resin> The softening point of the resin was measured using a capillary rheometer of the constant load extrusion method (trade name: Flow Characteristic Evaluation Flow Tester CFT-500D, manufactured by Shimadzu Corporation) according to the manual attached to the apparatus. In this apparatus, while applying a constant load from the upper part of the measurement material by a piston, the measurement sample filled in the cylinder was heated to melt, and the melted measurement sample was extruded from the die at the bottom of the cylinder, and a flow curve showing the relationship between the piston descent amount and the temperature at this time could be obtained. The "melting temperature in the 1 / 2 method" described in the manual attached to the "Flow Characteristic Evaluation Apparatus Flow Tester CFT-500D" was taken as the softening point. The melting temperature at 1 / 2 is calculated as follows. First, 1 / 2 of the difference between the piston descent amount (Smax) at the end of the outflow and the piston descent amount (Smin) at the start of the outflow is obtained (this is denoted as X. X = (Smax - Smin) / 2). Then, the temperature at which the piston descent amount in the flow curve becomes the sum of X and Smin is the melting temperature in the 1 / 2 method. As the measurement sample, about 1.0 g of resin was compression molded at about 10 MPa for about 60 seconds using a tablet molding compression machine (for example, NT-100H, manufactured by NPE System Co., Ltd.) in an environment of 25°C to form a columnar shape with a diameter of about 8 mm. The measurement conditions of the CFT-500D are as follows. Test mode: Temperature rising method Start temperature: 50°C Reached temperature: 200°C Measurement interval: 1.0°C Heating rate: 4.0 °C / min Piston cross-sectional area: 1.000 cm 2 Test load (piston load): 10.0 kgf / cm 2 (0.9807 MPa) Preheating time: 300 seconds Diameter of die hole: 1.0 mm Length of die: 1.0 mm

[0131] <Production Example of Resin 1> The following materials were charged into a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere. · 100 parts by mass of propylene oxide adduct of bisphenol A (average number of added moles: 2.2 moles) · 21 parts by mass of recovered polyethylene terephthalate (diethylene glycol content = 1.3% by mass) · 0.08 parts by mass of dibutyltin oxide While stirring the inside of the reaction vessel at 200 rpm, it was heated to 230 °C and reacted for 7 hours. Subsequently, it was cooled to 180 °C, 30 parts by mass of fumaric acid and 0.08 parts by mass of hydroquinone were added, and it was heated to 210 °C over 4 hours. Then, the pressure was reduced to 8 kPa and reacted until the softening point reached 103 °C to obtain Resin 1.

[0132] <Production Example of Resin 2> The following materials were charged into a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere. · 100 parts by mass of propylene oxide adduct of bisphenol A (average number of added moles: 2.2 moles) · 40 parts by mass of ethylene oxide adduct of bisphenol A (average number of added moles: 2.2 moles) · 13 parts by mass of dodecenyl succinic anhydride · 37 parts by mass of terephthalic acid · 12 parts by mass of trimellitic anhydride · 0.5 parts by mass of dibutyltin oxide While stirring the inside of the reaction vessel at 200 rpm, it was heated to 235°C and reacted for 4 hours. Thereafter, the pressure was reduced to 8 kPa and the reaction was carried out until the softening point reached 146°C to obtain Resin 2.

[0133] <Production Example of Toner Particles 1> · 70 parts by mass of Resin 1 · 30 parts by mass of Resin 2 · 5 parts by mass of Colorant ECB-301 (manufactured by Dainichi Seika Co., Ltd., C.I. Pigment Blue 15:3) parts · 1 part by mass of Charge Control Agent LR-147 (manufactured by Nippon Carlit Co., Ltd.) · 4 parts by mass of Release Agent NP-105 (manufactured by Mitsui Chemicals, Inc., melting point: 140°C) Using a Henschel mixer (FM-75 type, manufactured by Nippon Coke Industry Co., Ltd.), the above materials were mixed at a rotation speed of 20 s -1 and a rotation time of 5 min. Thereafter, they were kneaded in a twin-screw kneader (PCM-30 type, manufactured by Ikegai Corporation) set at a temperature of 120°C and a screw rotation speed of 200 rpm at a discharge temperature of 135°C. The obtained kneaded product was cooled at a cooling rate of 15°C / min and pulverized to a particle size of 1 mm or less with a hammer mill to obtain a coarsely pulverized product. The obtained coarsely pulverized product was finely pulverized with a mechanical pulverizer (T-250, manufactured by Freund Turbo Co., Ltd.). Further, classification was performed using a Faculity F-300 (manufactured by Hosokawa Micron Corporation) to obtain Toner Particles 1. The operating conditions were a classification rotor rotation speed of 130 s -1 and a dispersion rotor rotation speed of 120 s -1 .

[0134] <Production Example of Toner 1> The following materials were mixed with a Henschel mixer FM-10C type (manufactured by Nippon Coke Industry Co., Ltd.) at a rotation speed of 30 s -1 and a rotation time of 10 min to obtain Toner 1. · 100 parts by mass of Toner Particles 1 · 1.0 part by mass of Exterior Additive 1 Aerosil R-972 (manufactured by Nippon Aerosil Co., Ltd., average particle diameter 16 nm) · 1.0 part by mass of Exterior Additive 2 SI-Y (manufactured by Nippon Aerosil Co., Ltd., average particle diameter 40 nm)

[0135] (Production Example of Magnetic Carrier) · Number average particle diameter: 0.30 μm, magnetization strength at a magnetic field of 1000 / 4π (kA / m): 65 Am 2 / kg of magnetite 1 · Number average particle diameter: 0.50 μm, magnetization strength at a magnetic field of 1000 / 4π (kA / m): 65 Am 2 / kg of magnetite 2 To 100 parts of each of the above materials, 4.0 parts by mass of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane) was added, and high-speed mixing and stirring were carried out at 100 °C or higher in a container to treat each fine particle. · Phenol: 10% by mass · Formaldehyde solution: 6% by mass (40% by mass of formaldehyde, 10% by mass of methanol, 50% by mass of water) · Magnetite 1 treated with the above silane compound: 58% by mass · Magnetite 2 treated with the above silane compound: 26% by mass 100 parts of the above materials, 5 parts of 28% by mass aqueous ammonia solution, and 20 parts of water were put into a flask, and the temperature was raised to 85 °C in 30 minutes while stirring and mixing, and held for 3 hours to cause a polymerization reaction to cure the resulting phenol resin. Thereafter, the cured phenol resin was cooled to 30 °C, water was further added, the supernatant was removed, the precipitate was washed with water, and then air-dried. Then, this was dried under reduced pressure (5 mmHg or less) at a temperature of 60 °C to obtain a magnetic carrier dispersion type spherical magnetic carrier 1. The volume-based 50% particle diameter (D50) of the magnetic carrier 1 was 34 μm.

[0136] (Production Example of Developer 1) The following materials were mixed by a V-type mixer (V-20, manufactured by Seishin Enterprise Co., Ltd.) to obtain Developer 1. · Toner 1: 8 parts by mass · Magnetic carrier 1: 92 parts by mass

[0137] [Example 1] The manufactured electrophotographic photoreceptor 1 was installed in the cyan station of the modified iR-ADV C5560F III electrophotographic copying machine manufactured by Canon Inc., and developer 1 was set in the developing unit as the developer.

[0138] [Evaluation 1: Evaluation of Pattern Memory] In an environment of 32.5°C / 85%RH, the conditions of the charging device and the exposure device were set so that the charging potential of the electrophotographic photoreceptor was -600 V and the exposure potential was -200 V, and the conditions of the developing device were set so that the developing potential was -420 V. As the pattern image to be output, a pattern image having an image with a width of 10 mm and a length of 200 mm in a direction parallel to the paper feed direction was prepared. Next, using A4-sized plain paper, the above pattern image was output continuously 5000 times as a solid image with a density of 100% in cyan single color. Subsequently, when one full-surface halftone image with a density of 30% in cyan single color was output, it was evaluated whether a density difference occurred in the image portion with a width of 10 mm and a length of 200 mm output previously. The output images were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. (Evaluation Criteria for Pattern Memory) A: No density difference occurs B: A density difference at a level where it cannot be determined whether it exists occurs C: A slight density difference occurs (acceptable level in the present invention) D: A clear density difference occurs (unacceptable level in the present invention)

[0139] [Evaluation 2: Evaluation of Potential Fluctuation during Repeated Use] The above electrophotographic apparatus was installed in an environment of 23°C / 50%RH, and the conditions of the charging device and the exposure device were set so that the charging potential of the electrophotographic photoreceptor was -600 V and the exposure potential was -200 V, and the conditions of the developing device were set so that the developing potential was -420 V. At a cyan station equipped with an electrophotographic photoreceptor, a character image with a printing rate of 1% in monochrome was repeatedly printed 10,000 times on A4-sized plain paper. The initial exposure potential was compared with the exposure potential after 10,000 repetitions of image formation, and this was taken as the value of potential fluctuation (ΔVl). After 10,000 sheets of paper had passed, it was left for 5 minutes, the developing cartridge was replaced with a potential measuring device, and the exposure potential (Vlb) after repeated use was measured. The difference between the exposure potential after repeated use and the initial exposure potential (Vla) was taken as the exposure potential fluctuation amount (ΔVl = |Vlb| - |Vla|). The results of evaluation according to the following evaluation criteria are shown in Table 3. (Evaluation criteria for ΔVl) A: ΔVl is 0 V or more and less than 30 V (excellent) B: ΔVl is 30 V or more and less than 40 V (somewhat excellent) C: ΔVl is 40 V or more and less than 50 V (acceptable level in the present invention) D: ΔVl is 50 V or more (unacceptable level in the present invention)

[0140] [Examples 2 to 12, Comparative Example 1] The electrophotographic apparatus was evaluated in the same manner as in Example 1, except that the types of the electrophotographic photoreceptor and the developer were changed as shown in Table 3. The evaluation results are shown in Table 3.

[0141]

Table 3

[0142] [Production Example 2 of toner] [Preparation of amorphous resin A1] · Polyethylene terephthalate (molecular weight: 2000, intrinsic viscosity: 0.1) : 20.9 parts (42.0 mol%) · Propylene oxide adduct of bisphenol A (average number of added moles: 2.0 mol) : 47.4 parts (29.0 mol%) · Terephthalic acid: 15.8 parts (18.3 mol%) ·Dodecenyl succinic acid: 15.8 parts (10.6 mol%) ·Titanium tetrabutoxide (esterification catalyst): 0.5 part ·Gallic acid (promoter): 0.1 part The above materials were weighed into a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. The molar ratio of polyethylene terephthalate is the value as the total number of units obtained by summing the number of units derived from ethylene glycol and the number of units derived from terephthalic acid. Next, after replacing the inside of the flask with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200°C.

[0143] Furthermore, the pressure inside the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 5 hours while maintaining the temperature at 200°C. After confirming that the weight average molecular weight reached 6700, the temperature was lowered to stop the reaction, and an amorphous resin A1 having a polyethylene terephthalate segment in the molecule was obtained. The physical properties of the amorphous resin A1 obtained by the above-described measurement method are shown in Table 4.

[0144] <Preparation of Amorphous Resins A2 to A11> In the preparation of the amorphous resin A1, the reaction was carried out in the same manner except that the types and amounts of the polyethylene terephthalate and the polymerizable monomers were changed as shown in Table 4, and amorphous resins A2 to A11 having a polyethylene terephthalate segment in the molecule were obtained. The physical properties of the amorphous resins A2 to A11 obtained by the above-described measurement method are shown in Table 4.

[0145]

Table 4-1

Table 4-2

[0146] The abbreviations in Table 4 are as follows. BPA-PO: Propylene oxide adduct of bisphenol A (average number of added moles 2.0 mol)

[0147] <Preparation of Amorphous Resin B1> · Polyethylene terephthalate (molecular weight: 2000, intrinsic viscosity: 0.1) : 4.1 parts (9.8 mol%) · Propylene oxide adduct of bisphenol A (average number of added moles 2.0 mol) : 57.8 parts (42.8 mol%) · Terephthalic acid: 29.9 parts (41.9 mol%) · Trimellitic acid: 7.0 parts (4.5 mol%) · Stearic acid: 1.2 parts (1.0 mol%) · Titanium tetrabutoxide (esterification catalyst): 0.5 part · Gallic acid (promoter): 0.1 part The above materials were weighed into a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. Next, after replacing the inside of the flask with nitrogen gas, the temperature was gradually increased while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200 °C.

[0148] Furthermore, the pressure inside the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 5 hours while maintaining the temperature at 200 °C. After confirming that the weight average molecular weight reached 1000, the temperature was lowered to stop the reaction, and amorphous resin B1 was obtained. The physical properties of amorphous resin B1 obtained by the above-described measurement method were such that the SP value was 11.54 (cal / cm 3 ) 0.5 It was.

[0149] <Preparation of Crystalline Polyester C1> · Ethylene glycol: 10.2 parts (48.2 mol%) · Tetradecanedioic acid: 81.3 parts (48.3 mol%) · Behenic acid: 8.5 parts (3.5 mol%) · Titanium tetrabutoxide (esterification catalyst): 0.5 part The above materials were weighed into a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. Next, after replacing the inside of the flask with nitrogen gas, the temperature was gradually increased while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200 °C.

[0150] Furthermore, while reducing the pressure in the reaction vessel to 8.3 kPa and maintaining the temperature at 200 °C, after reacting for 5 hours, the temperature was lowered to stop the reaction, and crystalline polyester C1 was obtained. The physical properties of crystalline polyester C1 obtained by the above-described measurement method were such that the SP value was 10.09 (cal / cm 3 ) 0.5 .

[0151] <Production Example of Toner 2> · Amorphous resin A1: 66 parts · Amorphous resin B1: 34 parts · Crystalline polyester C1: 10 parts · Fischer-Tropsch wax (peak temperature of the maximum endothermic peak: 100 °C): 5 parts · Carbon black: 5 parts · Sodium phosphate tribasic: 0.03 part Using a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.), the above materials were mixed at a rotation speed of 1500 rpm for a rotation time of 5 minutes, and then kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Corporation) set at a temperature of 130 °C. The obtained kneaded product was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized product. The obtained coarsely pulverized product was finely pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Industry Co., Ltd.). Further, classification was performed using a Faculity (F-300, manufactured by Hosokawa Micron Corporation) to obtain toner particles 1. The operating conditions were a classification rotor rotation speed of 11000 rpm and a dispersion rotor rotation speed of 7200 rpm. · Toner particles 1: 95 parts · Inorganic fine particles with large particle size: Fumed silica surface-treated with hexamethyldisilazane (Median diameter (D50) based on the number basis is 120 nm) 4 parts · Inorganic fine particles with small particle size: Titanium oxide fine particles surface-treated with isobutyltrimethoxysilane (Median diameter (D50) based on the number basis is 10 nm) 1 part The above materials were mixed in a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Machinery Co., Ltd.) at a rotational speed of 1900 rpm for 10 minutes to obtain Toner 1 exhibiting negative chargeability. Table 5 shows the physical properties of Toner 2 obtained by the above-described measurement method.

[0152] <Manufacturing Examples of Toners 3 to 19> In the manufacturing example of Toner 2, the same operations as in the manufacturing example of Toner 2 were performed except that the types and amounts of the amorphous resin A and the additives were changed as shown in Table 5, to obtain Toners 3 to 19. Table 5 shows the physical properties of Toners 3 to 19 obtained by the above-described measurement method.

[0153]

Table 5

[0154] The abbreviations in Table 5 are as follows. PNa: Trisodium phosphate

[0155] <Manufacturing Examples of Developers 2 to 19> In the manufacturing example of Developer 1, the same operations were performed except for the changes as shown in Table 6, to obtain Developers 2 to 19.

[0156]

Table 6

[0157] [Examples 13 to 30] The electrophotographic apparatus was evaluated in the same manner as in Example 1 except that the types of the electrophotographic photoreceptor and the developer were changed as shown in Table 7. Also, the evaluation of scratch resistance and low-temperature fixability was performed by the methods shown below. Table 7 shows the evaluation results.

[0158] [Evaluation 3: Scratch Resistance] As the image forming apparatus, a modified machine of the Canon digital commercial printer imagePress C800 for printing was used, and the two-component developer 1 was put into the cyan developing device. The modification points of the apparatus were the fixing temperature, the process speed, and the DC voltage V of the developer carrierDC 1. The charging voltage V of the electrophotographic photoreceptor D 2. And the laser power was changed so that it could be freely set. For the image output evaluation, an FFh image (solid image) with a desired image ratio was output, and V was adjusted so that the toner loading amount on the FFh image on the paper would be as desired DC V D 3. And the laser power were adjusted to conduct postoperative evaluation. FFh is a value representing 256 gradations in hexadecimal notation, where 00h is the first gradation (blank part) of 256 gradations, and FFh is the 256th gradation (solid part) of 256 gradations Paper: UPM FINESSE GLOSS 300GSM Toner loading amount on paper: 0.05mg / cm 2 (2Fh image) (The toner loading amount is adjusted by the DC voltage V of the developer carrier DC 1. The charging voltage V of the electrophotographic photoreceptor D 2. And the laser power) Evaluation image: An image of 3m × 15cm is placed at the center of the above A4 paper Fixing test environment: Normal temperature and humidity environment (temperature 23°C / humidity 50%RH (hereinafter N / N)) Fixing temperature: 180°C Process speed: 377mm / sec The above evaluation image was output and the scratch resistance was evaluated. Specifically, using a surface property tester HEIDON TYPE14FW manufactured by Shinto Kagaku Co., Ltd., a 200g weight was placed, and scratching was performed at a speed of 60mm / min and a length of 30mm with a needle having a diameter of 0.75mm, and the evaluation was performed based on the scratches generated on the image. The area ratio of the toner peeling was obtained by binarizing the area where toner peeling occurred with respect to the scratched area by image processing (Evaluation criteria) A: 0.0% B: 0.1% or more and less than 0.4% C: 0.4% or more and less than 0.9% D: 0.9% or more and less than 1.1% E: 1.1% or more

[0159] [Low-temperature fixability] Paper: GFC-081 (81.0g / m 2(Sold by Canon Marketing Japan Inc.) Toner loading amount on paper: 0.50 mg / cm 2 (The toner loading amount is adjusted by the DC voltage V of the developer carrier DC , the charging voltage V of the electrophotographic photoreceptor D , and the laser power) Evaluation image: A 2 cm × 5 cm image is placed at the center of the above A4 paper Test environment: Low temperature and low humidity environment: Temperature 15°C / Humidity 10% RH (hereinafter referred to as "L / L") Fixing temperature: 150°C Process speed: 630 mm / sec The above evaluation image was output, and the low-temperature fixability was evaluated. The value of the decrease rate of the image density was used as the evaluation index for the low-temperature fixability.

[0160] Using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), first, the image density at the center was measured. Next, a load of 4.9 kPa (50 g / cm 2 ) was applied to the fixed image by rubbing with silicone paper (5 round trips), and the image density was measured again.

[0161] Then, the decrease rate of the image density before and after rubbing was calculated using the following formula. The obtained decrease rate of the image density was evaluated according to the following evaluation criteria. If the evaluation was A to C, it was judged to be good.

[0162] Decrease rate of image density (%) = (Image density before rubbing - Image density after rubbing) / Image density before rubbing × 100 (Evaluation criteria) A: Decrease rate of image density less than 3% B: Decrease rate of image density 3% or more and less than 5% C: Decrease rate of image density 5% or more and less than 8% D: Decrease rate of image density 8% or more and less than 10% E: Decrease rate of image density 10% or more

[0163]

Table 7

[0164] The toner used in the electrophotographic apparatus of the present disclosure can use polyethylene terephthalate regenerated from used PET bottles and the like as toner materials, so the technology described in this specification can contribute to the realization of a sustainable society such as a decarbonized / circular society.

[0165] The disclosure of this embodiment includes the following configurations. [Configuration 1] Charging means for charging the surface of the electrophotographic photoreceptor, Image exposure means for irradiating the surface of the charged electrophotographic photoreceptor with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photoreceptor, Developing means having toner and developing the electrostatic latent image with the toner to form a toner image on the surface of the electrophotographic photoreceptor, Transfer means for transferring the toner image from the surface of the electrophotographic photoreceptor to a transfer material, Cleaning means for removing residual toner remaining on the surface of the electrophotographic photoreceptor after transferring the toner image from the surface of the electrophotographic photoreceptor to the transfer material, An electrophotographic apparatus having The electrophotographic photoreceptor has a surface layer containing a compound represented by the following formula (A), a binder resin, and silicon atom-containing particles, The silicon atom-containing particles are silica particles or silicone resin particles, The toner has toner particles containing a polyester resin having a polyethylene terephthalate segment, An electrophotographic apparatus characterized by this. [Chemical formula] (In formula (A), a 1 ~a 6 each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a dialkylamino group, or a substituted or unsubstituted aryl group, or may be bonded to each other to form a ring structure. b 1~b 5 , c 1 ~c 5 and d 1 ~d 5 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a dialkylamino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted arylthio group, or may be bonded to each other to form a ring structure. Ar 1 and Ar 2 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted heterocyclic group, or may be bonded to each other to form a ring structure. However, Ar 1 and Ar 2 will not both be hydrogen atoms.) [Configuration 2] The electrophotographic apparatus according to Configuration 1, wherein the mass ratio of the compound represented by the formula (A) to the silicon atom-containing particles contained in the surface layer is 3:1 to 20:1. [Configuration 3] The electrophotographic apparatus according to Configuration 1 or 2, wherein the silicon atom-containing particles are silica particles. [Configuration 4] The electrophotographic apparatus according to any one of Configurations 1 to 3, wherein the number average primary particle diameter of the silicon atom-containing particles is 5 nm or more and 300 nm or less. [Configuration 5] The toner is a toner having toner particles containing a binder resin, The binder resin contains an amorphous resin A and a crystalline polyester C, The amorphous resin A is the polyester resin, and as a structure forming a polyester skeleton, (i) the polyethylene terephthalate segment, and (ii) at least one structure selected from the group consisting of units represented by the following formulas (1) to (4), has, [Chemical formula] (In the formula, R 1 represents an alkyl group having 6 to 16 carbon atoms or an alkenyl group having 6 to 16 carbon atoms, A represents a hydrocarbon group, * represents a bonding part in the polyester skeleton, and m represents an integer of 2 or more.) [Chemical formula] (In the formula, R 2 represents an alkyl group having 6 to 16 carbon atoms or an alkenyl group having 6 to 16 carbon atoms, B represents a hydrocarbon group, * represents a bonding part in the polyester skeleton, and n represents an integer of 2 or more.) [Chemical formula] (In the formula, * represents a bonding part in the polyester skeleton, and x represents an integer of 6 to 16.) [Chemical formula] (In the formula, * represents a bonding part in the polyester skeleton, and y represents an integer of 6 to 16.) When the SP value of the amorphous resin A is SP A (cal / cm 3 ), and the SP value of the crystalline polyester C is SP 0.5 (cal / cm C ), when the following formula (C) is satisfied by the SP 3 and the SP 0.5 , A 1.00 ≦ SP C − SP ≦ 1.35 ··· (C) A − SP C ≦ 1.35 ··· (C) The toner contains a phosphorus element derived from a phosphorus compound, and when the content of the phosphorus element in the toner is W P (ppm) based on the mass of the toner, the electrophotographic apparatus according to any one of Configurations 1 to 4, characterized in that the W P satisfies the following formula (D). 5 ≦ W P ≦ 500 ··· (D) [Configuration 6] Said W P The electrophotographic apparatus according to Configuration 5 in which the following formula (E) is satisfied. 20 ≤ W P ≤ 500 ··· (E)

Explanation of Signs

[0166] 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Image 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 101 Support 102 Undercoat layer 103 Charge generation layer 104 Charge transport layer

Claims

1. Charging means for charging the surface of an electrophotographic photoreceptor, Image exposure means for irradiating the surface of the charged electrophotographic photoreceptor with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photoreceptor, Developing means having toner for developing the electrostatic latent image with the toner to form a toner image on the surface of the electrophotographic photoreceptor, Transfer means for transferring the toner image from the surface of the electrophotographic photoreceptor to a transfer material, Cleaning means for removing residual toner remaining on the surface of the electrophotographic photoreceptor after transferring the toner image from the surface of the electrophotographic photoreceptor to the transfer material, An electrophotographic apparatus having: The electrophotographic photoreceptor has a surface layer containing a compound represented by the following formula (A), a binder resin, and silicon atom-containing particles, The silicon atom-containing particles are silica particles or silicone resin particles, The toner has toner particles containing a polyester resin having a polyethylene terephthalate segment, An electrophotographic apparatus characterized by the above. 【Chemical 1】 (In formula (A), a １ to a ６ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a dialkylamino group, or a substituted or unsubstituted aryl group, or may be bonded to each other to form a ring structure. b １ to b ５ , c １ to c ５ and d １ to d ５ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a dialkylamino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted arylthio group, or may be bonded to each other to form a ring structure. Ar １ and Ar ２ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted heterocyclic group, or may be bonded to each other to form a ring structure. However, Ar １ and Ar ２ will not both be hydrogen atoms.)

2. The electrophotographic apparatus according to claim 1, wherein the mass ratio of the compound represented by the formula (A) to the silicon atom-containing particles contained in the surface layer is 3:1 to 20:

1.

3. The electrophotographic apparatus according to claim 1, wherein the silicon atom-containing particles are silica particles.

4. The electrophotographic apparatus according to any one of claims 1 to 3, wherein the number average primary particle diameter of the silicon atom-containing particles is 5 nm or more and 300 nm or less.

5. The toner is a toner having toner particles containing a binder resin, The binder resin contains an amorphous resin A and a crystalline polyester C, The amorphous resin A is the polyester resin, and as a structure forming a polyester skeleton, (i) the polyethylene terephthalate segment, and (ii) at least one structure selected from the group consisting of units represented by the following formulas (1) to (4), has, [Chemical 2] (wherein, R １ represents an alkyl group having 6 to 16 carbon atoms or an alkenyl group having 6 to 16 carbon atoms, A represents a hydrocarbon group, * represents a bonding portion in the polyester skeleton, m represents an integer of 2 or more. ) [Chemical Formula 3] (wherein, R ２ represents an alkyl group having 6 to 16 carbon atoms or an alkenyl group having 6 to 16 carbon atoms, B represents a hydrocarbon group, * represents a bonding portion in the polyester skeleton, n represents an integer of 2 or more. ) 【Chemical Formula 4】 (In the formula, * represents a bonding portion in the polyester skeleton, x represents an integer of 6 to 16. ) 【Chemical Formula 5】 (In the formula, * represents a bonding portion in the polyester skeleton, y represents an integer of 6 to 16. ) When the SP value of the amorphous resin A is SP Ａ (cal / cm ３ ) ０．５ and the SP value of the crystalline polyester C is SP Ｃ (cal / cm ３ ) ０．５ , when the SP Ａ and the SP Ｃ satisfy the following formula (C), 1.00 ≤ SP Ａ -SP Ｃ ≤ 1.35... (C) The toner contains a phosphorus element derived from a phosphorus compound, When the content of the phosphorus element in the toner is W (ppm) based on the mass of the toner, Ｐ the electrophotographic apparatus according to any one of claims 1 to 3, characterized in that the W Ｐ satisfies the following formula (D). 5 ≤ W Ｐ ≤ 500... (D)

6. The aforesaid W Ｐ The electrophotographic apparatus according to claim 5, wherein the aforesaid W satisfies the following formula (E). 20 ≤ W Ｐ ≤ 500... (E)

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