Electrophotographic device

Abstract

To provide an excellent electrophotographic device that uses a developing roller for preventing filming, and that can prevent a reduction in transfer efficiency after durable use and scattering of toner, and maintains high image quality throughout a period from the initial stage until after the durable use.SOLUTION: An electrophotographic device has an electrophotographic photoreceptor, electrifying means, exposure means, and developing means. The electrophotographic photoreceptor has a single-layer sensitive layer containing a charge generating material, a hold transport material, an electron transport material, and a first binder resin. The photosensitive layer contains a polyester resin having a specific structural unit as the first binder resin. The developing means is a developing roller having a shaft body, an elastic layer provided on the outer periphery of the shaft body, and a coating layer provided on the outer periphery of the elastic layer. The coating layer contains a second binder resin and silica particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic apparatus. [Background technology]

[0002] In recent years, there has been a demand for electrophotographic image forming apparatuses (hereinafter also referred to as "electrophotographic apparatuses") that have a longer life and are capable of forming higher quality images, and there is a desire to provide an apparatus that has high stability in the quality of images output after repeated use (hereinafter also referred to as after durability). As the electrophotographic photoreceptor mounted in an electrophotographic apparatus or a process cartridge, an organic electrophotographic photoreceptor (hereinafter simply referred to as "electrophotographic photoreceptor" or "photoreceptor") containing an organic photoconductive material (charge generating material) is used. In recent electrophotographic apparatuses, in addition to addressing the above-mentioned need for a longer life, there has been a demand for improving image quality by suppressing a decrease in transfer efficiency after endurance use, and maintaining high image quality from the initial stage through endurance use. The developing roller used in an electrophotographic device is brought into pressure contact with or close to a latent image carrier with a predetermined contact width, and carries a thin layer of toner formed by a coating blade. Therefore, the developing roller is required to be flexible and easily deformable, have excellent set resistance, have the ability to impart charge to the developer, and further, be suppressed from adhesion of the developer.

[0003] Patent documents 1 and 2 describe a developing roller in which an elastic layer made of a rubber material that has been made conductive is provided on the outer periphery of a mandrel, and a layer made of a resin material is further provided on the outer periphery of that elastic layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-114392 [Patent Document 2] Japanese Patent Application Publication No. 2019-168614 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the study by the present inventors, when an electrophotographic apparatus equipped with the developing rollers described in Patent Documents 1 and 2 is used for the purpose of suppressing the deterioration of filming, problems related to transfer may occur after endurance testing. Specifically, toner scattering and a decrease in transfer efficiency may occur, leaving room for improvement.

[0006] Therefore, an object of the present invention is to provide an excellent electrophotographic device that uses a developing roller to suppress filming, which can suppress a decrease in transfer efficiency and toner scattering after endurance, and maintains high image quality from the beginning through to end of endurance. [Means for solving the problem]

[0007] An electrophotographic apparatus according to one aspect of the present invention is an electrophotographic apparatus comprising: an electrophotographic photosensitive member; a charging unit that charges the surface of the electrophotographic photosensitive member; an exposure unit that irradiates the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; and a developing unit that has toner and develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has a single-layer photosensitive layer containing a charge generating material, a hole transport material, an electron transport material, and a first binder resin, and the photosensitive layer contains, as the first binder resin, a polyester resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2): [ka] [ka] The developing means is a developing roller having a shaft, an elastic layer provided on the outer periphery of the shaft, and a coating layer provided on the outer periphery of the elastic layer, and the coating layer contains a second binder resin and silica particles. [Effects of the Invention]

[0008] According to the present invention, in an electrophotographic device using a developing roller for suppressing filming, it is possible to suppress a decrease in transfer efficiency and toner scattering after endurance, and an excellent electrophotographic device is provided that maintains high image quality from the beginning through endurance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of a layer structure of an electrophotographic photosensitive member used in the present invention. [Figure 2] 1 is a diagram showing an example of a layer structure of an electrophotographic photosensitive member used in the present invention. [Figure 3] 1 is a diagram showing an example of a layer structure of an electrophotographic photosensitive member used in the present invention. [Figure 4] 1 is a schematic perspective view showing an example of a schematic configuration of a developing roller used in the present invention. [Figure 5] 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below with reference to preferred embodiments. In Patent Document 2, filming is suppressed by using a developing roller containing silica particles. However, according to the inventors' investigations, there were cases where transfer efficiency decreased and toner scattering occurred after durability testing. It was speculated that this was due to a difference in the chargeability of the toner between the areas of the surface of the developing roller where silica particles are present and those where they are not. In other words, it was thought that the difference in toner chargeability caused some toner to be transferred early before the nip of the transfer belt, resulting in scattering and a decrease in image quality. It was also thought that some toner remained untransferred during transfer, resulting in a decrease in transfer efficiency.

[0011] Based on the above speculation, the inventors have conducted various studies to find means for suppressing the decline in transfer efficiency and toner scattering after endurance testing in an electrophotographic device equipped with a developing roller containing silica in its surface layer, and for maintaining high image quality from the initial stage through to the end of endurance testing, and have arrived at the configuration of the present invention. That is, in the present invention, when the coating layer of the developing roller provided in the electrophotographic apparatus is characterized by containing a binder resin and silica particles, the electrophotographic photosensitive member provided in the electrophotographic apparatus has the following configuration: The inventors have found that this suppresses a decrease in transfer efficiency and toner scattering after endurance testing, and makes it possible to maintain high image quality from the beginning through to the end of endurance testing.

[0012] First, the electrophotographic photoreceptor has a single-layer photosensitive layer containing a charge generating material, a hole transport material, an electron transport material, and a binder resin, and the photosensitive layer contains, as the binder resin, a polyester resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2): [ka] [ka]

[0013] Hereinafter, the binder resin contained in the photosensitive layer of the electrophotographic photosensitive member may be referred to as a first binder resin, and the binder resin contained in the coating layer of the developing roller may be referred to as a second binder resin.

[0014] The structural unit represented by formula (1) exhibits a highly electron-accepting structure, and when combined with the structural unit represented by formula (2), it undergoes resonance stabilization, resulting in even higher electron-accepting properties. It is believed that an electrophotographic photoreceptor containing a polyester resin having the structural unit represented by formula (1) and the structural unit represented by formula (2) is effective in leveling the potential of toner with uneven chargeability. In other words, when a single-layer photosensitive layer contains a polyester resin with high electron-accepting properties, the electrophotographic photoreceptor becomes relatively negatively charged, which is thought to level out the difference in the positive charge of the toner, thereby suppressing transfer defects.

[0015] [Electrophotographic photoreceptor] The electrophotographic photoreceptor used in the present invention has at least a support and a photosensitive layer formed on the support. The method for producing the electrophotographic photoreceptor used in the present invention includes a method in which a coating liquid for each layer described below is prepared, and the coating liquid is applied in the desired layer order and dried. In this case, the coating liquid can be applied by dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, etc. Among these, dip coating is preferred from the viewpoints of efficiency and productivity. Hereinafter, each component of the electrophotographic photosensitive member will be described in detail.

[0016] (single-layer photoreceptor) A single-layer photoreceptor 1, which is an example of the photoreceptor used in the present invention, will be described below with reference to Figures 1 to 3. Figures 1 to 3 are partial cross-sectional views showing examples of the layer structure of the single-layer photoreceptor 1.

[0017] 1, the single-layer photoreceptor 1 includes, for example, a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 included in the single-layer photoreceptor 1 is a single-layer (one-layer) photosensitive layer. The photosensitive layer 3 contains a charge generating material, a hole transport material, an electron transport material, and a first binder resin.

[0018] 2, the single-layer photoreceptor 1 may further include an undercoat layer 4 (intermediate layer) in addition to the support 2 and the photosensitive layer 3. That is, in the single-layer photoreceptor 1, the photosensitive layer 3 may be provided directly on the support 2, or, as shown in FIG. 2, it may be provided on the support 2 via the undercoat layer 4.

[0019] Furthermore, as shown in FIG. 3, the single-layer photoreceptor 1 may further include a protective layer 5 in addition to the support 2 and the photosensitive layer 3. The protective layer 5 is provided on the photosensitive layer 3. In the present invention, as shown in FIGS. 1 and 2, it is preferable that the single-layer photoreceptor 1 does not include the protective layer 5, and the photosensitive layer 3 is provided as the surface layer of the single-layer photoreceptor 1. By providing the photosensitive layer 3 as the surface layer, which contains a polyester resin having a structural unit represented by formula (1) and a structural unit represented by formula (2) as the first binder resin, it is easy to suppress a decrease in transfer efficiency and toner scattering after endurance testing. The thickness of the photosensitive layer 3 is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0020] <Support> In the present invention, the electrophotographic photoreceptor has a support. In the present invention, the support is preferably a conductive support having electrical conductivity. The shape of the support may be cylindrical, belt-like, sheet-like, or the like. Among these, a cylindrical support is preferred. The surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like. The support is preferably made of a metal, a resin, a glass, or the like. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferred. Furthermore, the resin or glass may be made conductive by mixing or coating it with a conductive material.

[0021] <Undercoat layer> In the present invention, an undercoat layer may be provided on the support, which can improve adhesion between layers and provide a charge injection blocking function. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the resin include polyester resin, polyarylate resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinylphenol 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 contained in the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0022] Furthermore, for the purpose of improving electrical properties, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, a conductive polymer, etc. Among these, it is preferable to use an electron transporting substance or a metal oxide. Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the above-mentioned monomer having the polymerizable functional group. Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, silicon dioxide, etc. Examples of metals include gold, silver, aluminum, etc. The undercoat layer may further contain additives. The thickness of the undercoat layer is preferably from 0.1 μm to 50 μm, more preferably from 0.2 μm to 40 μm, and particularly preferably from 0.3 μm to 30 μm. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0023] <Single-layer photosensitive layer> The electrophotographic photoreceptor used in the present invention has a single-layer photosensitive layer on a support or on an undercoat layer provided on a support. In the present invention, the single-layer photosensitive layer contains at least a first binder resin, a charge generating substance, a hole transporting substance, and an electron transporting substance.

[0024] [First binder resin] The first binder resin used in the photosensitive layer contains a polyester resin having a structural unit represented by formula (1) and a structural unit represented by formula (2). [ka] [ka]

[0025] The structural unit represented by formula (1) has a highly electron-accepting structure. Furthermore, when it is bonded to the structural unit represented by formula (2), it undergoes resonance stabilization, resulting in even higher electron-accepting properties. Therefore, it is believed that an electrophotographic photoreceptor having a photosensitive layer containing a polyester resin having the structural unit represented by formula (1) and the structural unit represented by formula (2) enhances the positive charging of the toner. Specifically, the present inventors believe that when a positively charged toner is developed on the electrophotographic photoreceptor and transferred to a transfer member, the electrophotographic photoreceptor becomes relatively negatively charged, which has the effect of leveling out the difference in the positive charging of the toner.

[0026] Furthermore, the polyester resin may have a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5) in addition to the structural unit represented by formula (1) and the structural unit represented by formula (2). [ka] [ka]

[0027] When the polyester resin having the structural unit represented by formula (1) and the structural unit represented by formula (2) further contains the structural unit represented by formula (4) and the structural unit represented by formula (5), the solubility of the polyester resin in a solvent is improved, and therefore a photosensitive layer can be formed satisfactorily. The polyester resin may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer.

[0028] In the polyester resin, M1 is the molar ratio of the structural unit represented by formula (1) to the sum of the molar amounts of the structural units constituting the polyester resin. M2 is the molar ratio of the structural unit represented by formula (2) to the sum of the molar amounts of the structural units constituting the polyester resin. M4 is the molar ratio of the structural unit represented by formula (4) to the sum of the molar amounts of the structural units constituting the polyester resin. M5 is the molar ratio of the structural unit represented by formula (5) to the sum of the molar amounts of the structural units constituting the polyester resin. From the viewpoint of suppressing a decrease in transfer efficiency, M1 / (M1+M4) is preferably greater than 0.30, and more preferably 0.55 or greater.

[0029] A larger molar fraction of M2 / (M2+M5) is preferable from the viewpoint of suppressing a decrease in transfer efficiency, but from the viewpoint of solubility in a solvent, it is preferable that the molar fraction be 0 or more and 0.50 or less. Improved solubility in a solvent allows for the formation of a good photosensitive layer. From the viewpoint of solubility in a solvent, M4 / (M1+M4) is preferably 0.30 or more and 0.70 or less. M5 / (M2+M5) is preferably less than 0.70 in terms of suppressing a decrease in transfer efficiency, and is preferably greater than 0.50 in terms of solubility in solvents. Furthermore, it is preferable that M4 / (M1+M4) is 0.30 or more and 0.70 or less, and M2 / (M2+M5) is 0 or more and 0.50 or less. In the polyester resin, when the sum of the molar amounts of the structural units derived from dicarboxylic acids constituting the polyester resin is defined as MC and the molar amount of the structural unit represented by formula (1) is defined as M1, it is preferable that M1 / MC is 0.50 or more.

[0030] The viscosity average molecular weight of the polyester resin is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. When the viscosity average molecular weight of the polyester resin is 10,000 or more, the abrasion resistance of the photoreceptor is improved. On the other hand, the viscosity average molecular weight of the polyester resin is preferably 80,000 or less, more preferably 70,000 or less. When the viscosity average molecular weight of the polyester resin is 80,000 or less, the polyester resin is easily dissolved in a solvent for forming the photosensitive layer.

[0031] Examples of bisphenols for constituting the bisphenol-derived repeating units in the polyester resin include compounds represented by the following formula (BP-2) and (BP-5). Hereinafter, the compound represented by the following formula (BP-2) may be referred to as compound (BP-2). Furthermore, the compound represented by the following formula (BP-5) may be referred to as compound (BP-5). [ka] [ka]

[0032] Furthermore, examples of dicarboxylic acids for constituting the dicarboxylic acid-derived repeating units in the polyester resin include compounds represented by the following formula (DC-1) and compounds represented by the following formula (DC-4). Hereinafter, the compound represented by the following formula (DC-1) may be referred to as compound (DC-1). Furthermore, the compound represented by the following formula (DC-4) may be referred to as compound (DC-4). [ka] [ka]

[0033] The bisphenol ratio in the resin can be adjusted by changing the amounts of compound (BP-2) and compound (BP-5) added when producing the polyester resin. Similarly, the dicarboxylic acid ratio in the resin can be adjusted by changing the amounts of compound (DC-1) and compound (DC-4) added when producing the polyester resin.

[0034] Bisphenols (e.g., compounds (BP-2) and (BP-5)) may be derivatized to aromatic diacetates before use. Dicarboxylic acids (e.g., compounds (DC-1) and (DC-4)) may be derivatized before use. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. Dicarboxylic acid dichlorides are compounds having a structure in which two "-C(=O)-OH" groups of a dicarboxylic acid are each replaced with a "-C(=O)-Cl" group.

[0035] In the polycondensation of bisphenol and dicarboxylic acid, a base and / or a catalyst may be added. An example of the base is sodium hydroxide. An example of the catalyst is benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salt, triethylamine, and trimethylamine.

[0036] The photosensitive layer may contain only the above-mentioned polyester resin as the first binder resin, or may further contain a binder resin other than the above-mentioned polyester resin (hereinafter, sometimes referred to as other binder resin) within a range that does not impair the effects of the present invention.

[0037] Examples of other binder resins include thermoplastic resins (more specifically, polyester resins other than the above-mentioned polyester resins, polycarbonate resins, styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid based resins and urethane-acrylic acid based copolymers).

[0038] The first binder resin contained in the photosensitive layer preferably contains 50% by mass or more of a polyester resin having a structural unit represented by formula (1) and a structural unit represented by formula (2). That is, the content of the polyester resin is preferably 50% by mass or more with respect to the total mass of the first binder resin. The polymer components recovered from the photosensitive layer were analyzed in deuterated chloroform. 1 Obtained by H-nuclear magnetic resonance analysis 1 The structure of the polyester resin of the present invention can be determined by H-nuclear magnetic resonance spectroscopy. A specific method will be described below. ■Reprecipitation of resin in the photosensitive layer - Turn off the photosensitive element (hereinafter simply referred to as the "drum"). Cut the drum using a jigsaw at a position 10 cm from the end of the drum in the generatrix direction. Wash the inside of the 10cm cut out drum. Wipe the inside of the cylinder with Silbon paper soaked in chloroform. Dissolves the photosensitive layer. Immerse 3 cm of the cut end of the drum in chloroform. (Pour approximately 60cc of chloroform into a 100mL beaker and soak for 5 minutes at room temperature.) ·Concentrate (concentrate liquefaction). Concentrate using a rotary evaporator until the volume reaches 2 mL and then stop. ·Resedimentation. Prepare 50 mL of a methanol / acetone mixture (volume ratio 1:1), and add the entire amount of the above concentrated solution dropwise while stirring. Filter. Perform suction filtration using a Kiriyama funnel. (Funnel: SU-40, filter paper: No. 5C-40, both manufactured by Kiriyama Seisakusho Co., Ltd.) · Dry. The residue on the filter paper is collected with a spatula and dried in vacuo (70°C for 1 hour). NMR measurements Measurement sample preparation 20 mg of sample is dissolved in 1 g of deuterated chloroform containing tetramethylsilane as a reference substance, and the entire amount is transferred to an NMR tube. (Deuterated chloroform: Sigma-Aldrich Japan Co., Ltd., chloroform-d, model number 612200) (NMR tube: Norell ST500-7, model number S3010) ·NMR measurement Equipment: Bruker AVANCE500 Conditions: Proton NMR, automated measurement by ICON-NMR Accumulation count: 32 times Reference peak: The methyl group peak of tetramethylsilane is set at 0 ppm.

[0039] [Charge-generating material] Examples of charge-generating materials include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one type of charge-generating material, or may contain two or more types of charge-generating materials.

[0040] Phthalocyanine pigments are pigments having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. As the metal phthalocyanine, titanyl phthalocyanine is preferred. Titanyl phthalocyanine is represented by the following formula (CGM-1): [ka]

[0041] Phthalocyanine pigments may be crystalline or amorphous. Examples of metal-free phthalocyanine crystals include X-type crystals of metal-free phthalocyanine (hereinafter, sometimes referred to as X-type metal-free phthalocyanine). Examples of titanyl phthalocyanine crystals include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, sometimes referred to as α-type, β-type, and Y-type titanyl phthalocyanine, respectively). For example, in digital optical electrophotographic devices (e.g., laser beam printers or facsimiles using light sources such as semiconductor lasers), it is preferable to use photoreceptors sensitive in the wavelength region of 700 nm or more. Because of their high quantum yield in the wavelength region of 700 nm or more, phthalocyanine pigments are preferred as charge-generating materials, with metal-free phthalocyanine or titanyl phthalocyanine being more preferred. Furthermore, titanyl phthalocyanine is even more preferred as charge-generating materials, with Y-type titanyl phthalocyanine being particularly preferred.

[0042] In the CuKα characteristic X-ray diffraction spectrum, Y-type titanyl phthalocyanine does not have a peak at 26.2°, but has, for example, a main peak at a Bragg angle (2θ±0.2°) of 27.2°. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak with the first or second highest intensity in the Bragg angle (2θ±0.2°) range of 3° to 40°. The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (titanyl phthalocyanine) is loaded into a sample holder of an X-ray diffractometer (e.g., Rigaku Corporation's "RINT (registered trademark) 1100"). Next, the X-ray diffraction spectrum is measured under the conditions of a Cu X-ray tube, a tube voltage of 40 kV, a tube current of 30 mA, and a CuKα characteristic X-ray wavelength of 1.542 Å. The measurement range (2θ) is, for example, 3° to 40° (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0043] The content of the charge generating substance in the photosensitive layer is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the binder resin.

[0044] [Electron transport material] The electron transport material preferably contains at least one compound selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), a compound represented by the following formula (13), a compound represented by the following formula (14), a compound represented by the following formula (15), and a compound represented by the following formula (16). It is believed that the inclusion of the above electron transport material in the photosensitive layer increases the compatibility between the polyester resin and the hole transport material described below, and improves the internal uniformity of the photosensitive layer, thereby enhancing the effects of the present invention.

[0045] [ka] [ka] [ka] [ka] [ka] [ka] [ka] (Q in Eq. (10) 1 and Q 2 , Q in Eq. (11) 11 , Q 12 , and Q 13 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31and Q 32 , Q in Eq. (14) 41 , Q 42 , Q 43 , and Q 44 , Q in Eq. (15) 51 , Q 52 , Q 53 , Q 54 , Q 55 , and Q 56 , and Q in equation (16) 61 and Q 62 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom; and Y in formula (15) 1 and Y 2 each independently represents an oxygen atom or a sulfur atom.

[0046] Q in equation (10) 1 and Q 2 , Q in Eq. (11) 11 ~Q 13 , Q in Eq. (12) 21 ~Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 ~Q 44 , Q in Eq. (15) 51 ~Q 56 , and Q in equation (16) 61 and Q 62 Preferably, each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 preferably represents an oxygen atom.

[0047] Q in equation (10) 1 and Q2 , Q in Eq. (11) 11 ~Q 13 , Q in Eq. (12) 21 ~Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 ~Q 44 , Q in Eq. (15) 51 ~Q 56 , and Q in equation (16) 61 and Q 62 The alkyl group having 1 to 6 carbon atoms represented by is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group, and particularly preferably a methyl group, an isopropyl group, a tert-butyl group, or a 1,1-dimethylpropyl group.

[0048] Q in equation (10) 1 and Q 2 , Q in Eq. (11) 11 ~Q 13 , Q in Eq. (12) 21 ~Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 ~Q 44 , Q in Eq. (15) 51 ~Q 56 , and Q in equation (16) 61 and Q 62 The aryl group having 6 to 14 carbon atoms represented by is preferably an aryl group having 6 to 10 carbon atoms, more preferably a phenyl group.

[0049] Here, the alkyl group having 1 to 6 carbon atoms that the aryl group having 6 to 14 carbon atoms may have as a substituent is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. Furthermore, the halogen atom that the aryl group having 6 to 14 carbon atoms may have as a substituent is preferably a fluorine atom, a chlorine atom, or a bromine atom, and particularly preferably a chlorine atom. When an aryl group having 6 to 14 carbon atoms is substituted with a substituent, the number of substituents is preferably 1 to 5, and more preferably 1 or 2.

[0050] The aryl group having 6 to 14 carbon atoms and substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom is preferably a chlorophenyl group, a dichlorophenyl group, or an ethylmethylphenyl group, and more preferably a 4-chlorophenyl group, a 2,5-dichlorophenyl group, or a 2-ethyl-6-methylphenyl group.

[0051] A suitable example of the compound represented by formula (10) is a compound represented by formula (E-4) below. A suitable example of the compound represented by formula (11) is a compound represented by formula (E-5) below. A suitable example of the compound represented by formula (12) is a compound represented by formula (E-7) below. A suitable example of the compound represented by formula (13) is a compound represented by formula (E-6) below. A suitable example of the compound represented by formula (14) is a compound represented by formula (E-8) below. A suitable example of the compound represented by formula (15) is a compound represented by formula (E-2) below and a compound represented by formula (E-3) below. A suitable example of the compound represented by formula (16) is a compound represented by formula (E-1) below. Hereinafter, the compounds represented by formulas (E-1) to (E-8) below may be referred to as electron transport materials (E-1) to (E-8), respectively.

[0052] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0053] The content of the electron transport material in the photosensitive layer is preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 100 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the binder resin. The photosensitive layer may contain only one type of electron transport material, or may contain two or more types of electron transport materials.

[0054] [Hole transport material] The hole transport substance preferably contains at least one compound selected from the group consisting of a compound represented by the following formula (20), a compound represented by the following formula (21), a compound represented by the following formula (22), a compound represented by the following formula (23), and a compound represented by the following formula (24). It is believed that the inclusion of the hole transport substance in the photosensitive layer increases the compatibility between the polyester resin and the electron transport substance, and improves the internal uniformity of the photosensitive layer, thereby enhancing the effects of the present invention.

[0055] [ka] [ka] [ka] [ka] [ka] (In formula (20), R11 , R 12 , R 13 , and R 14 each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; a1, a2, a3, and a4 each independently represent an integer of 0 to 5; and in formula (21), R 21 , R 22 , and R 23 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 24 , R 25 , and R 26 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; b1, b2, and b3 each independently represent 0 or 1; and in formula (22), R 31 , R 32 , and R 33 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom; d1, d2, and d3 each independently represent an integer of 0 to 5; and in formula (23), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group; R 47 and R 48 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group; e1, e2, e3, and e4 each independently represent an integer of 0 to 5; e5 and e6 each independently represent an integer of 0 to 4; e7 and e8 each independently represent 0 or 1; and in formula (24), R 50 and R 51 each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group; R 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having from 1 to 6 carbon atoms, each independently represents an integer of from 0 to 2, and each independently represents an integer of from 0 to 5.

[0056] In formula (20), when a1 represents an integer of 2 or more and 5 or less, a plurality of R 11 may represent the same group or different groups. When a2 represents an integer of 2 or more and 5 or less, multiple R 12 may represent the same group or different groups. When a3 represents an integer of 2 or more and 5 or less, multiple R 13 may represent the same group or different groups. When a4 represents an integer of 2 or more and 5 or less, multiple R 14 may represent the same group or different groups. 11 , R 12 , R 13 , and R 14 each independently preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. a1, a2, a3, and a4 each independently preferably represent an integer of 1 to 3, more preferably 1.

[0057] In formula (21), R 21 , R 22 , and R 23 R preferably each independently represents an alkyl group having 1 to 3 carbon atoms, and more preferably represents a methyl group. 21 , R 22 , and R 23 is preferably bonded to the meta position of the phenyl group relative to the ethenyl group or butadienyl group. 24 , R 25 , and 26 Each of b1, b2, and b3 preferably represents a hydrogen atom. It is preferable that b1, b2, and b3 all represent 0 or all represent 1.

[0058] In formula (22), when d1 represents an integer of 2 or more and 5 or less, a plurality of R 31 may represent the same group or different groups. When d2 represents an integer of 2 or more and 5 or less, multiple R 32 may represent the same group or different groups. When d3 represents an integer of 2 or more and 5 or less, multiple R 33 may represent the same group or different groups. 34 preferably represents a hydrogen atom. d1, d2, and d3 each preferably represent 0.

[0059] In formula (23), when e1 represents an integer of 2 or more and 5 or less, a plurality of R 41 may represent the same group or different groups. When e2 represents an integer of 2 or more and 5 or less, multiple R 42 may represent the same group or different groups. When e3 represents an integer of 2 or more and 5 or less, multiple R 43 may represent the same group or different groups. When e4 represents an integer of 2 or more and 5 or less, multiple R 44 may represent the same group or different groups. When e5 represents an integer of 2 or more and 4 or less, multiple R 45 may represent the same group or different groups. When e6 represents an integer of 2 or more and 4 or less, multiple R 46 may represent the same group or different groups. 41 ~R 46 R preferably each independently represents an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or an ethyl group. 47 and R 48 preferably represents a hydrogen atom. e1, e2, e3, and e4 each independently represent an integer of 0 or more and 2 or less, and it is more preferable that e1 and e2 represent 0 and e3 and e4 represent 2. e5 and e6 preferably represent 0. It is preferable that e7 and e8 both represent 0 or both represent 1.

[0060] In formula (24), when f3 represents an integer of 2 or more and 5 or less, a plurality of R 50 may represent the same group or different groups. When f4 represents an integer of 2 or more and 5 or less, multiple R 51 may represent the same group or different groups. 50 and R 51 Preferably, each independently represents an alkyl group having 1 to 6 carbon atoms. 52 and R 53 R preferably represents a hydrogen atom or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms. 54 ~R 58 Preferably, each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Preferably, f1 and f2 both represent 0, both represent 1, or both represent 2. Preferably, f3 and f4 each independently represent 0 or 1. R 50 and R 51 The alkyl group having 1 to 6 carbon atoms represented by R is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. 52 and R 53 The phenyl group represented by the formula (I) which may be substituted with an alkyl group having 1 to 6 carbon atoms is preferably a phenyl group or a phenyl group substituted with an alkyl group having 1 to 3 carbon atoms. The phenyl group substituted with an alkyl group having 1 to 3 carbon atoms is preferably a methylphenyl group, and more preferably a 4-methylphenyl group. 54 ~R 58 The alkyl group having 1 to 6 carbon atoms represented by R is preferably an alkyl group having 1 to 4 carbon atoms, and is preferably a methyl group, an ethyl group, or an n-butyl group. 54 ~R 58 The alkoxy group having 1 to 6 carbon atoms represented by the formula (I) is preferably an alkoxy group having 1 to 3 carbon atoms, more preferably an ethoxy group.

[0061] A suitable example of the compound represented by formula (20) is a compound represented by formula (H-11) below. A suitable example of the compound represented by formula (21) is a compound represented by formula (H-7) below and a compound represented by formula (H-8) below. A suitable example of the compound represented by formula (22) is a compound represented by formula (H-6) below. A suitable example of the compound represented by formula (23) is a compound represented by formula (H-9) below and a compound represented by formula (H-10) below. A suitable example of the compound represented by formula (24) is a compound represented by formula (H-1) below, a compound represented by formula (H-2) below, a compound represented by formula (H-3) below, a compound represented by formula (H-4) below, and a compound represented by formula (H-5) below. Hereinafter, the compounds represented by formulas (H-1) to (H-11) may be referred to as hole transport substances (H-1) to (H-11), respectively.

[0062] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0063] The content of the hole transport substance in the photosensitive layer is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 30 parts by mass or more and 120 parts by mass or less, and even more preferably 50 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0064] The photosensitive layer may contain only one type of hole transport material, or may contain two or more types of hole transport materials. The photosensitive layer may further contain hole transport materials (hereinafter, sometimes referred to as "other hole transport materials") other than the hole transport materials represented by formulas (20), (21), (22), (23), and (24). Examples of other hole transport materials include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthylenediamine derivatives, N,N,N',N'-tetraphenylphenanthrylenediamine derivatives, and di(aminophenylethenyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole), and the like. azoles), styryl compounds (for example, 9-(4-diethylaminostyryl)anthracene), carbazole compounds (for example, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds.

[0065] [Additives] The photosensitive layer may contain additives as needed. Examples of additives include ultraviolet absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, waxes, donors, surfactants, plasticizers, sensitizers, and leveling agents. In particular, the photosensitive layer preferably contains a substance represented by the following formula (T-1): [ka]

[0066] [Developing roller] The developing roller used in the present invention will be described in detail below with reference to Fig. 4. Fig. 4 is a diagram showing an example of the schematic configuration of the developing roller used in the present invention.

[0067] [Shaft body] The shaft 12 is preferably a conductive shaft used in a conventionally known developing roller. The shaft 12 is preferably made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. The shaft 12 made of such a metal is generally known as a "core metal." Shaft 12 may contain an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. Shaft 12 may include, for example, a core made of an insulating resin and a plated layer provided on the core. Such shaft 12 can be obtained, for example, by plating a core made of an insulating resin to make it conductive. The shaft 12 is preferably a cored bar in order to obtain good electrical conductivity. The shape of the shaft 12 is preferably, for example, rod-like or tubular. The cross-sectional shape of the shaft 12 may be, for example, circular or elliptical, or may be non-circular such as polygonal. The outer peripheral surface of the shaft 12 may be subjected to treatment such as cleaning, degreasing, or primer treatment in order to improve adhesion to the elastic layer 13. The axial length of the shaft 12 is not particularly limited and may be adjusted appropriately depending on the configuration of the electrophotographic apparatus in which it is installed. For example, when the printing target is A4 size, the axial length of the shaft 12 is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. The diameter (diameter of the circumscribing circle) of the shaft 12 is also not particularly limited and may be adjusted appropriately depending on the configuration of the electrophotographic apparatus in which it is installed. For example, the outer diameter (diameter of the circumscribing circle) of the shaft 12 is preferably 4 mm or more and 14 mm or less, and more preferably 6 mm or more and 10 mm or less.

[0068] [Elastic layer] The elastic layer 13 is formed by heat-curing a rubber composition on the outer peripheral surface of the shaft body 12. The rubber composition for forming the elastic layer 13 preferably contains rubber, a conductivity imparting agent, and, as desired, various additives.

[0069] (Rubber composition) -Rubber- Examples of the rubber in the rubber composition include silicone rubber or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluororubber. The rubber in the rubber composition is preferably silicone rubber, silicone-modified rubber, or urethane rubber. Furthermore, silicone rubber or silicone-modified rubber is particularly preferred in terms of its ability to reduce compression set, excellent flexibility in low-temperature environments, and excellent heat resistance and electrostatic properties. Examples of silicone rubber include crosslinked organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane.

[0070] -Conductive agent- Preferred examples of the conductivity-imparting agent include conductive agents having an electron conduction mechanism, such as carbon black, graphite, copper, aluminum, nickel, iron powder, and conductive metal oxides; conductive agents having an ion conduction mechanism, such as alkali metal salts and quaternary ammonium salts; and conductive agents having conductive composite particles in which conductive particles, such as carbon black particles, are attached to the surfaces of silica particles. As the conductivity-imparting agent, carbon black is particularly preferred. The carbon black is not particularly limited, and for example, acetylene black, furnace black, channel black, ketjen black, thermal black, etc. are preferably used. As the carbon black, one of these may be used alone, or two or more may be used in combination. In order to obtain the desired electrical resistance, two or more of various conductive agents may be used in combination. The content of the conductivity imparting agent in the rubber composition is preferably 0.5% by mass to 20% by mass, more preferably 1.0% by mass to 15% by mass, and even more preferably 2.0% by mass to 10% by mass, based on the total amount of the rubber composition. By adjusting the content of the conductivity imparting agent to be within the above range, the resistance value of the developing roller 11 becomes more stable, printing performance is improved, and the compression set of the elastic layer 13 is reduced, thereby improving the durability of the developing roller 11.

[0071] -Various additives- The rubber composition may further contain various additives other than those described above, such as auxiliaries (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, mold release agents, and solvents. Examples of silicone rubber compositions using silicone rubber as the rubber in the rubber composition include addition-curable millable conductive silicone rubber compositions and addition-curable liquid conductive silicone rubber compositions.

[0072] The addition-curable millable conductive silicone rubber composition may contain, for example, (A) an organopolysiloxane represented by the following average composition formula (S1), (B) a filler, and (C) a conductivity-imparting agent. R 1 n SiO (4-n) / 2 (S1) In formula (S1), n is a positive number of 1.95 or more and 2.05 or less. 1 represents a substituted or unsubstituted monovalent hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less. 1 may be the same as each other, or may be partially or entirely different from each other.

[0073] R 1 Examples of the R include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl groups, cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl, allyl, butenyl, and hexenyl groups, aryl groups such as phenyl and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. 1 or may be a group in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with a substituent. The substituent may be, for example, a halogen atom, a cyano group, etc. Examples of the hydrocarbon group having a substituent include a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group.

[0074] The molecular chain terminals of the (A) organopolysiloxane are preferably blocked with a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, or a trialalkylsilyl group such as a trivinylsilyl group. (A) organopolysiloxane preferably has two or more alkenyl groups in the molecule. (A) organopolysiloxane preferably has two or more alkenyl groups in the molecule. 1Of these, it is preferable that the alkenyl group account for 0.001 mol % or more and 5 mol % or less (more preferably 0.01 mol % or more and 0.5 mol % or less).Vinyl groups are particularly preferable as the alkenyl groups contained in (A) organopolysiloxane.

[0075] (A) organopolysiloxane can be obtained, for example, by cohydrolytic condensation of one or more organohalosilanes, or by ring-opening polymerization of a cyclic polysiloxane such as a siloxane trimer or tetramer. (A) organopolysiloxane may be essentially a linear diorganopolysiloxane, or may be partially branched. (A) organopolysiloxane may also be a mixture of two or more types with different molecular structures. The organopolysiloxane (A) preferably has a kinematic viscosity at 25° C. of 100 cSt or more, more preferably 100,000 cSt or more and 10,000,000 cSt or less. The degree of polymerization of the organopolysiloxane (A) is preferably, for example, 100 or more, more preferably 3,000 or more and 10,000 or less.

[0076] (B) The filler may be, for example, a silica-based filler, such as fumed silica or precipitated silica. Silica-based fillers include R 2 Si(OR 3 A surface-treated silica-based filler that has been surface-treated with a silane coupling agent represented by formula (R) 3 can be preferably used. 2 may be a group having a vinyl group or an amino group, such as a glycidyl group, a vinyl group, an aminopropyl group, a methacryloxy group, an N-phenylaminopropyl group, or a mercapto group. 3 may be an alkyl group, such as a methyl group, an ethyl group, or the like.

[0077] The amount of silica-based filler blended is preferably 11 to 39 parts by mass, and more preferably 15 to 35 parts by mass, per 100 parts by mass of (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 to 80 μm, and more preferably 2 to 40 μm. The average particle size of the silica-based filler can be measured as the median size using a particle size distribution analyzer based on laser diffraction.

[0078] The amount of the (C) conductivity-imparting agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the (A) organopolysiloxane, and is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the (A) organopolysiloxane.

[0079] The addition-curable millable conductive silicone rubber composition may further contain additives other than (A) to (C), such as auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, mold release agents, and solvents.

[0080] Specific examples of additives include dimethylsiloxane oils having a lower degree of polymerization than the (A) organopolysiloxane, polyether-modified silicone oils, silanols, low-molecular-weight siloxanes terminated at both ends with silanol groups, such as diphenylsilanediol and α,ω-dimethylsiloxanediol, and dispersants such as silanes. Specific examples of additives include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. Additives that may be used include various carbon functional silanes and various olefin-based elastomers for improving adhesion, moldability, etc.

[0081] The addition-curable liquid conductive silicone rubber composition may contain, for example, (D) an organopolysiloxane having two or more alkenyl groups in the molecule, (E) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule, (F) a filler, (G) a conductivity imparting agent, and (H) an addition reaction catalyst. The organopolysiloxane (D) is preferably a compound represented by the following average composition formula (S2): R 4 a SiO (4-a) / 2 (S2) In formula (S2), a represents a positive number of 1.5 or more and 2.8 or less, preferably 1.8 or more and 2.5 or less, and more preferably 1.95 or more and 2.05 or less. 4 represent substituted or unsubstituted monovalent hydrocarbon groups which may be the same or may be wholly or partially different from each other. 4 At least two of the hydrocarbon groups are alkenyl groups. The number of carbon atoms in the hydrocarbon groups is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less. R 4 As for the above R 1 The same groups as those exemplified as R 4 At least two of the R 4 is preferably an alkyl group. The alkenyl group is preferably a vinyl group, and the alkyl group is preferably a methyl group. 4 Of these, for example, 90% or more may be alkyl groups (preferably methyl groups).

[0082] The alkenyl group content in the (D) organopolysiloxane is, for example, 1.0 × 10 -6 mol / g or more 5.0×10 -3 mol / g or less, and preferably 5.0×10 -6 mol / g or more 1.0×10 -3 It is more preferable that it is mol / g or less. The organopolysiloxane (D) is preferably liquid at 25° C. and has a viscosity at 25° C. of preferably 100 mPa·s or more and 1,000,000 mPa·s or less, and more preferably 200 mPa·s or more and 100,000 mPa·s or less. The average degree of polymerization of the organopolysiloxane (D) is preferably 100 or more and 800 or less, and more preferably 150 or more and 600 or less.

[0083] The organohydrogenpolysiloxane (E) is preferably a compound represented by the following average composition formula (S3). R 5 b H c SiO (4-b-c) / 2 (S3) In formula (S3), b is a positive number of 0.7 or more and 2.1 or less, c is a positive number of 0.001 or more and 1.0 or less, and bc is a positive number of 0.8 or more and 3.0 or less. 5 R may be the same or may be partially or completely different from each other, and represent substituted or unsubstituted monovalent hydrocarbon groups. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 10 or less. 5 As for the above R 1 Examples of the groups include the same groups as those exemplified as above.

[0084] The organohydrogenpolysiloxane (E) has two or more, preferably three or more, silicon-bonded hydrogen atoms (Si—H) per molecule, and the number of silicon-bonded hydrogen atoms per molecule of the organohydrogenpolysiloxane (E) is preferably 200 or less, more preferably 100 or less. In (E) organohydrogenpolysiloxane, the content of hydrogen atoms bonded to silicon atoms is preferably 0.001 mol / g or more and 0.017 mol / g or less, and more preferably 0.002 mol / g or more and 0.015 mol / g or less.

[0085] (E) Organohydrogenpolysiloxanes include, for example, methylhydrogenpolysiloxanes capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with trimethylsiloxy groups, dimethylpolysiloxanes capped at both ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with dimethylhydrogensiloxane groups, methylhydrogensiloxane-diphenylsiloxane copolymers capped at both ends with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers capped at both ends with trimethylsiloxy groups, and (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 and copolymers consisting of (CH3)2HSiO units. 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 and copolymers consisting of units.

[0086] The amount of (E) organohydrogenpolysiloxane blended is preferably 0.1 to 30 parts by mass, and more preferably 0.3 to 20 parts by mass, per 100 parts by mass of (D) organopolysiloxane. The molar ratio of Si-H in (E) organohydrogenpolysiloxane to alkenyl groups in (D) organopolysiloxane is preferably 0.3 to 5.0, and more preferably 0.5 to 2.5.

[0087] The filler (F) may be, for example, an inorganic filler. By blending the filler (F) into the addition-curable liquid conductive silicone rubber composition, the compression set is reduced, the volume resistivity is stabilized over time, and sufficient roller durability is obtained. The average particle diameter of the (F) filler is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less. When the average particle diameter of the (F) filler is 1 μm or more, the change in volume resistivity over time is further suppressed. Furthermore, when the average particle diameter of the (F) filler is 30 μm or less, an elastic layer 13 with even greater durability can be obtained. The average particle diameter of the (F) filler can be measured as the median diameter using a particle size distribution measuring device using a laser light diffraction method.

[0088] (F) The bulk density of the filler is 0.1 g / cm 3 More than 0.5g / cm 3 Preferably, it is 0.15 g / cm or less. 3 More than 0.45g / cm 3 It is more preferable that the bulk density of the (F) filler is less than or equal to 0.05g. Adjusting the bulk density of the (F) filler to fall within the above range makes it possible to further reduce compression set, further suppress changes in volume resistivity over time, and obtain an elastic layer 13 with even greater durability. The bulk density of the (F) filler can be determined based on the apparent specific gravity measurement method of JIS K6223.

[0089] Examples of the (F) filler include diatomaceous earth, perlite, mica, calcium carbonate, glass flakes, hollow fillers, etc. Among these, pulverized products of diatomaceous earth, perlite, and expanded perlite can be suitably used as the (F) filler. The amount of (F) filler blended is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less, per 100 parts by mass of (D) organopolysiloxane.

[0090] The blend amount of (G) the conductivity imparting agent is preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of (D) the organopolysiloxane.

[0091] The (H) addition reaction catalyst may be any catalyst capable of activating the addition reaction between the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane. Examples of the (H) addition reaction catalyst include catalysts containing platinum group elements. Examples of catalysts containing platinum group elements include platinum-based catalysts (e.g., platinum black, platinic chloride, chloroplatinic acid, reaction products of chloroplatinic acid and monohydric alcohols, complexes of chloroplatinic acid and olefins, platinum bisacetoacetate, etc.), palladium-based catalysts, and rhodium-based catalysts. The amount of the (H) addition reaction catalyst may be a catalytic amount. For example, the amount of the (H) addition reaction catalyst is preferably an amount such that the amount of platinum group element is 0.5 ppm by mass or more and 1000 ppm by mass or less relative to the total mass of the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane. Furthermore, the amount of the (H) addition reaction catalyst is more preferably an amount such that the amount of platinum group element is 1 ppm by mass or more and 500 ppm by mass or less relative to the total mass of the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane.

[0092] The addition-curable liquid conductive silicone rubber composition may further contain additives other than (D) to (H), such as auxiliary agents (chain extenders, crosslinking agents, etc.), foaming agents, dispersants, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, mold release agents, diluents, reactive diluents, and solvents. Specific examples of additives include dispersants such as low-molecular-weight siloxane esters, polyether-modified silicone oils, silanols, and phenylsilanediols. Other examples include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. Various carbon functional silanes and various olefin-based elastomers may also be used to improve adhesion, moldability, and the like. Halogen compounds may also be used to impart flame retardancy.

[0093] The viscosity of the addition-curable liquid conductive silicone rubber composition at 25°C is preferably 5 Pa·s or more and 500 Pa·s or less, and more preferably 5 Pa·s or more and 200 Pa·s or less.

[0094] The elastic layer 13 is formed on the outer peripheral surface of the shaft 12 by heat curing and molding simultaneously or successively using a known molding method. The method for curing the rubber composition may be any method that can apply the heat necessary to cure the rubber composition, and the molding method for the elastic layer 13 is not particularly limited and may include continuous vulcanization by extrusion molding, pressing, injection molding, etc. For example, if the rubber composition is an addition-curable millable conductive silicone rubber composition, extrusion molding or the like can be selected, and if the rubber composition is an addition-curable liquid conductive silicone rubber composition, a molding method using a mold can be selected, for example.

[0095] The heating temperature when curing the rubber composition is preferably 100°C to 500°C, particularly 120°C to 300°C, for an addition-curable millable conductive silicone rubber composition, and a time of several seconds to 1 hour, particularly 10 seconds to 35 minutes. For addition-curable liquid conductive silicone rubber compositions, the heating temperature is preferably 100°C to 300°C, particularly 110°C to 200°C, and a time of 5 minutes to 5 hours, particularly 1 hour to 3 hours. If necessary, secondary vulcanization may be performed. For addition-curable millable conductive silicone rubber compositions, curing conditions are selected, for example, at 100°C to 200°C and for 1 hour to 20 hours. For addition-curable liquid conductive silicone rubber compositions, curing conditions are selected, for example, at 120°C to 250°C and for 2 hours to 70 hours.

[0096] The rubber composition can also be foamed and cured by a known method to easily form a sponge-like elastic layer 13 containing bubbles. The thickness of the elastic layer 13 is not particularly limited, but is preferably 0.1 mm to 6 mm, and more preferably 1 mm to 4 mm. Note that the "thickness" in this specification refers to the thickness perpendicular to the axial direction of the developing roller 11. The outer diameter of the elastic layer 13 is not particularly limited, but is preferably 6 mm to 25 mm. The outer peripheral surface of the elastic layer 13 may be subjected to a surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, itro treatment, or flame treatment to improve adhesion to the coating layer 14. The method for forming the elastic layer 13 is not particularly limited. For example, the elastic layer 13 may be formed by extrusion molding of a silicone rubber composition, LIMS molding, or other methods. The elastic layer 13 may also be formed by grinding or polishing an elastomer (cured silicone rubber composition) formed on the shaft 12.

[0097] [Coating layer] The coating layer 14 is provided on the outer periphery of the elastic layer 13 and on the outermost surface of the developing roller. The coating layer 14 preferably contains a second binder resin and silica particles dispersed in the second binder resin. The coating layer 14 is formed by applying a resin composition to the outer periphery of the elastic layer 13 or an optional primer layer, and then heat-curing the applied resin composition. The resin composition contains at least a urethane preparation component for forming a urethane resin as the second binder resin, and silica particles. The coating layer 14 does not necessarily have to be formed by heat-curing a resin composition; it may be a layer formed by a silicone coating treatment using ethyl silicate, or a treatment that includes a titanium-based, aluminum-based, or zirconium-based material in the treatment agent. The resin composition is applied by a known coating method, such as a coating method in which a coating liquid of the resin composition is applied, a dipping method in which the elastic layer 13 or the like is immersed in the coating liquid, or a spray coating method in which the coating liquid is sprayed onto the elastic layer 13 or the like. The resin composition may be applied as is, or a coating liquid obtained by adding a volatile solvent, such as alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, or ester solvents such as ethyl acetate and butyl acetate, or water, to the resin composition may be applied.

[0098] The method for curing the resin composition thus coated may be any method that can add heat or moisture necessary for curing the resin composition. Examples of methods for curing the resin composition include heating the elastic layer 13 coated with the resin composition using a heater, or leaving the elastic layer 13 coated with the resin composition in a high-humidity environment. The heating temperature for heat-curing the resin composition is preferably, for example, 100°C or higher and 200°C or lower, and more preferably 120°C or higher and 160°C or lower. The heating time is preferably 10 minutes or higher and 120 minutes or lower, and more preferably 30 minutes or higher and 60 minutes or lower. Instead of coating, a method can be employed in which the resin composition is laminated onto the outer peripheral surface of the elastic layer 13 or the primer layer by a known molding method such as extrusion molding, press molding, or injection molding, and then the laminated resin composition is cured. In the coating layer 14 thus formed, the precursor that forms the resin and the conductivity imparting agent, etc., which will be described later, may react to form a single body or a complex, or the conductivity imparting agent may be dispersed in the resin without reacting with the precursor that forms the resin.

[0099] (slip angle) The sliding angle of the surface of the developing roller used in the present invention is preferably 10° or more and 40° or less. The surface of the developing roller refers to the surface of the coating layer 14. In this specification, the "sliding angle" refers to the angle between the horizontal plane and the base when the developing roller begins to slide toward one end, as follows: First, a base with a PET (polyethylene terephthalate) film laid on it is placed horizontally (angle of 0° with the horizontal plane), and the developing roller is placed on the base so that the longitudinal direction of the base is parallel to the axial direction of the developing roller. Next, while fixing one longitudinal end of the base, the other end is raised to gradually tilt the base. By setting the sliding angle of the surface of the developing roller to 10° or more, the developing roller can effectively carry and transport the developer to the photosensitive member. Furthermore, by setting the sliding angle to 40° or less, the developer adheres to the developing roller and then easily detaches, allowing the developer to be supplied in a predetermined amount according to the image data. In other words, by setting the sliding angle to 10° or more and 40° or less, the developer can be properly carried and transported, maintaining high-quality images.

[0100] (Thickness) The thickness of the coating layer 14 is preferably 1 μm or more and 20 μm or less. By adjusting the thickness of the coating layer 14 within the above range, it is possible to effectively suppress filming and improve durable printing performance. The components contained in the coating layer 14 will be described below.

[0101] (urethane resin) The coating layer 14 contains a urethane resin as a second binder resin. The urethane preparation component, which is a precursor for forming the urethane resin, may be any component capable of forming a urethane resin, such as a mixture of a polyol and an isocyanate. The polyol may be any of the various polyols commonly used in the preparation of polyurethanes, and is preferably at least one polyol selected from polyether polyols, polyester polyols, polyacrylate polyols, and polycarbonate polyols.

[0102] Examples of polyether polyols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various modified products or mixtures of these. Polyester polyols have two or more ester bonds and two or more hydroxyl groups in their molecules. Examples of polyester polyols include condensation products of dicarboxylic acids and polyols. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, and isophthalic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid.

[0103] Polyacrylate polyols are copolymers of hydroxyl group-containing monomers with other olefinically unsaturated monomers, such as (meth)acrylic acid esters, styrene, α-methylstyrene, vinyltoluene, vinyl esters, mono- and di-alkyl maleic esters, and mono- and di-alkyl fumaric esters, α-olefins, and other unsaturated oligomers and polymers. In this specification, the term "(meth)acrylic acid" refers to a compound of acrylic acid or methacrylic acid. For example, "(meth)acrylic acid ester" refers to an acrylic acid ester or a methacrylic acid ester.

[0104] Polycarbonate polyols have two or more carbonate bonds and two or more hydroxyl groups in their molecules. Examples of polycarbonate polyols include condensation reaction products of polyols and carbonate compounds. Examples of carbonate compounds include dialkyl carbonates, diaryl carbonates, and alkylene carbonates. Examples of polyols used as raw materials for polycarbonate polyols include diols such as hexanediol and butanediol, and triols such as 2,4-butanetriol.

[0105] The isocyanate may be any of various isocyanates commonly used in the preparation of polyurethanes, such as aliphatic isocyanates, aromatic isocyanates, and derivatives thereof. The isocyanate is preferably an aliphatic isocyanate, as it has excellent storage stability and is easy to control the reaction rate. Examples of aromatic isocyanates include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also known as tolylene diisocyanate, TDI), 3,3'-bitrylene-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (a dimer of 2,4-TDI), xylene diisocyanate, naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI), tolidine diisocyanate (TODI), and metaphenylene diisocyanate. Examples of aliphatic isocyanates include hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), orthotoluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane-1,4-diisocyanate, and triphenylmethane-4,4',4''-triisocyanate. Examples of the derivatives include polyisocyanate polynuclear compounds, urethane-modified compounds (including urethane prepolymers) modified with polyols or the like, dimers formed by uretidione formation, isocyanurate-modified compounds, carbodiimide-modified compounds, uretonimine-modified compounds, allophanate-modified compounds, urea-modified compounds, and biuret-modified compounds. The polyisocyanate may be used alone or in combination of two or more. The polyisocyanate preferably has a molecular weight of 500 to 2,000, more preferably 700 to 1,500.

[0106] The mixing ratio of polyol and polyisocyanate in the mixture is not particularly limited. Usually, the molar ratio (NCO / OH) of the hydroxyl group (OH) contained in the polyol to the isocyanate group (NCO) contained in the polyisocyanate is preferably 0.7 or more and 1.15 or less. This molar ratio (NCO / OH) is more preferably 0.85 or more and 1.10 or less in order to prevent hydrolysis of polyurethane. In practice, however, an amount equivalent to three to four times the appropriate molar ratio may be blended, taking into account the working environment and operational errors. In addition to the polyol and polyisocyanate, the urethane-preparing components may contain an auxiliary agent that is usually used in the reaction between a polyol and a polyisocyanate, such as a chain extender or a crosslinking agent. Examples of the chain extender and crosslinking agent include glycols, hexanetriol, trimethylolpropane, and amines.

[0107] (silica particles) The coating layer 14 of the developing roller 11 used in the present invention contains silica particles. The silica particles may be subjected to a surface treatment such as hydrophobicity or hydrophilicity, if necessary. One or more types of silica particles may be used. The average particle diameter (median diameter (d50)) of the silica particles is preferably 10 nm or more and 5 μm or less, from the viewpoint of favorable developer support. The content of silica particles is preferably 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the urethane preparation component in the resin composition for forming the coating layer 14. By using a content of 1 part by weight or more, the surface of the coating layer 14 can be improved in slipperiness, and the developer can be well supported and transported to the photoreceptor. Furthermore, by using a content of 10 parts by weight or less, the dispersion of the particles can be improved, the uniformity of the surface condition of the coating layer 14 can be maintained, and filming can be effectively suppressed. The content of silica particles is more preferably 2 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the urethane preparation component.

[0108] (Conductive agent) The coating layer 14 may further contain a conductivity imparting agent. The conductivity imparting agent is not particularly limited as long as it is a component that can impart conductivity to the coating layer 14. The conductivity imparting agent may be the same as that used in the elastic layer 13. The amount of the conductivity imparting agent is not particularly limited and may be adjusted appropriately depending on the type of conductivity imparting agent, the desired conductivity performance, etc. Furthermore, one type of conductivity imparting agent may be used alone, or two or more types may be used in combination.

[0109] (Other ingredients) The coating layer 14 may further contain additives other than those mentioned above. For example, the coating layer 14 may further contain additives such as a silane coupling agent, a lubricant, a polymerization catalyst, a dispersant, and a filler.

[0110] The coating layer 14 can be formed by applying a resin composition for forming the coating layer onto the elastic layer 13 and polymerizing the polyol component and the isocyanate component by heating, etc. The solvent used in the coating liquid is preferably a solvent capable of dissolving the polyol component and the polyisocyanate component, and may be, for example, ethyl acetate, butyl acetate, etc.

[0111] (Hydroxyl-containing ionic liquids without ether groups) The urethane resin composition that forms the coating layer 14 preferably contains a hydroxyl-containing ionic liquid that does not contain an ether group. An "ionic liquid" is a type of onium salt consisting of a cation and an anion, and is a liquid compound that has high conductivity and remains in a liquid state at least at temperatures near room temperature. In the present invention, the ionic liquid serves as an ionic conductive agent that imparts conductivity to the coating layer 14. The use of an ionic liquid can reduce the residual potential caused by long-term printing and effectively suppress filming.

[0112] The ionic liquid used in the present invention does not have an ether group in the molecule but has at least one hydroxyl group, preferably at a terminal. Examples of such ionic liquids include aliphatic amine-based ionic liquids having ammonium ions as the cations, pyridinium-based ionic liquids having pyridinium ions as the cations, and imidazolium-based ionic liquids having imidazolium ions as the cations. The urethane resin composition may contain one or more ionic liquids. The ionic liquid contains hydroxyl groups, which react with isocyanate, a material of the urethane resin, preventing the unreacted ionic liquid from bleeding out. Furthermore, the absence of ether groups in the ionic liquid reduces the water content in the urethane resin composition, preventing contamination of the image carrier, blade, and supply roller due to uncured urethane resin composition, and preventing horizontal and vertical streaks on the printed image.

[0113] The content of (c) ether-free hydroxyl-containing ionic liquid in the urethane resin composition is preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the total content of (a) polyacrylic polyol and (b) polyisocyanate. Furthermore, the content of (c) ether-free hydroxyl-containing ionic liquid in the coating layer 14 is preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the second binder resin. By ensuring that the content of the ionic liquid is 0.1 parts by mass or more per 100 parts by mass of the second binder resin, desirable conductivity for the developing roller can be ensured. By ensuring that the content of the ionic liquid is 10 parts by mass or less per 100 parts by mass of the second binder resin, excessive crosslink density can be prevented when the ionic liquid has two or more hydroxyl groups. Therefore, wear of the outermost layer coat or toner degradation due to repeated printing can be suppressed, and the initial image quality can be maintained.

[0114] (Crosslinked (meth)acrylic acid ester resin particles) The coating layer 14 preferably contains at least one resin particle selected from the group consisting of crosslinked acrylic ester resin particles and crosslinked methacrylic ester resin particles. The crosslinked (meth)acrylic ester is used to form irregularities on the surface of the coating layer 14. The crosslinked (meth)acrylic ester is a resin particle formed by crosslinking a (meth)acrylic ester. Examples of acrylic esters include methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, hexyl methacrylate, and urethane (meth)acrylic ester. The crosslinked (meth)acrylic ester resin particles preferably have a recovery rate of 20% or more and a 10% compressive strength of 0.1 MPa or more and 2.2 MPa or less. From this viewpoint, among the above acrylic esters, urethane (meth)acrylic esters are particularly preferred. The crosslinked (meth)acrylic ester resin particles preferably have a recovery rate of 20% or more and a 10% compressive strength of 0.1 MPa or more and 2.2 MPa or less.

[0115] Here, the "restoration rate (%)" in the present invention refers to a value calculated as follows: First, a load of 9.8 mN is applied, and then the amount of displacement (displacement in particle diameter) is measured when the load is reduced to 0.98 mN. Next, the restoration rate (%) is calculated using the following mathematical formula 1 from the measured displacement in particle diameter and the particle diameter of the spherical particles before the load was applied. Recovery rate (%) = [particle diameter displacement (μm) / particle diameter (μm)] × 100 (Formula 1) (Conditions for measuring recovery rate) Test temperature: 23°C and 50% RH Upper pressure indenter: 50 μm diameter diamond flat indenter Lower pressure plate: SKS flat plate Measurement mode: Unloading test Load rate: 0.98mN / sec Maximum load: 9.8mN

[0116] In addition, the "10% compressive strength" in the present invention refers to a value measured by the following method. It is a value measured under the following measurement conditions using a microcompression testing machine MCT manufactured by Shimadzu Corporation. When a test force is applied to one spherical particle at a loading rate of 0.98 mN / sec, the test force at the point when the displacement reaches 10% of the particle diameter is taken as the compressive strength (MPa). (Compressive strength measurement conditions) Test temperature: 23°C and 50% RH Upper pressure indenter: 50 μm diameter diamond flat indenter Lower pressure plate: SKS flat plate Measurement mode: Compression test Load rate: 0.98mN / sec Maximum load: Up to 10% of particle size

[0117] An example of a commercially available crosslinked (meth)acrylic acid ester resin particle having a recovery rate of 20% or more and a 10% compressive strength of 0.1 MPa or more and 2.2 MPa or less is Techpolymer AFX-8 (manufactured by Sekisui Plastics Co., Ltd.).

[0118] The average particle size of the crosslinked (meth)acrylic ester resin particles is not particularly limited. However, if the average particle size is excessively large compared to the thickness of the coating layer 14, the surface irregularities of the coating layer 14 will become rough, making it easier for toner particles to remain in the recesses on the surface. On the other hand, if the average particle size is excessively small, protrusions will not be formed on the coating layer 14, which may cause the charging performance of the coating layer 14 to become unstable. Therefore, from the viewpoint of stabilizing the charging performance of the developing roller and suppressing the remaining of toner particles in the coating layer 14, it is preferable that the average particle size of the crosslinked (meth)acrylic ester resin particles be equal to the thickness of the coating layer 14. Specifically, the average particle size of at least one resin particle selected from the group consisting of crosslinked acrylic ester resin particles and crosslinked methacrylic ester resin particles is preferably 1 μm or more and 15 μm or less. More preferably, the average particle size of the crosslinked (meth)acrylic ester resin particles is 2 μm or more and 10 μm or less. The average particle size of the crosslinked (meth)acrylic acid ester resin particles is a value obtained by the following method for measuring the volume average diameter of resin particles.

[0119] [Method for measuring volume average diameter of resin particles] The volume mean diameter of resin particles (arithmetic mean diameter based on volume-based particle size distribution) is measured using a Coulter Multisizer II (a measuring device manufactured by Beckman Coulter) in the following manner. Note that this measurement is performed after calibration using a 50 μm aperture in accordance with Reference Manual for the Coulter Multisizer (1987) published by Coulter Electronics Limited. Specifically, 0.1 g of resin particles were pre-dispersed in 10 ml of a 0.1 wt % nonionic surfactant to obtain a dispersion using a touch mixer (Yamato Scientific Co., Ltd., "TOUCHMIXER MT-31") and an ultrasonic cleaner (Velvo Coolia Co., Ltd., "ULTRASONIC CLEANER VS-150") for the pre-dispersion. Next, prepare a beaker filled with ISOTON (registered trademark) II (measurement electrolyte manufactured by Beckman Coulter, Inc.) attached to the Coulter Multisizer II main body. The dispersion is dropped into this beaker with a dropper while gently stirring, and the reading of the densitometer on the screen of the Coulter Multisizer II main body is adjusted to around 10%. Next, enter the aperture size (diameter) as 50 μm, the current (aperture electrode) as 800 μA, the gain as 4, and the polarity (polarity of the internal electrode) as + into the Coulter Multisizer II main unit, and perform the measurement in manual mode. During the measurement, gently stir the contents of the beaker to prevent air bubbles from entering, and stop the measurement when the measurement of 100,000 resin particles has been completed. The arithmetic mean diameter in the particle size distribution based on the volume of 100,000 resin particles is defined as the volume mean diameter.

[0120] The content of the crosslinked (meth)acrylic acid ester resin particles is not particularly limited, and the higher the content, the more effectively plastic deformation of the coating layer 14 can be suppressed. However, if the content is too high, the density of the crosslinked acrylic resin particles distributed in the coating layer 14 increases, which may result in the surface roughness of the coating layer 14 becoming rough. In this case, toner particles tend to remain on the surface of the coating layer 14, resulting in a decrease in the charging performance of the developing roller. Therefore, from the viewpoint of suppressing plastic deformation of the coating layer 14 while achieving an appropriate surface roughness that prevents toner particles from remaining, the content of the crosslinked (meth)acrylic acid ester resin particles is preferably 5 to 50 parts by weight per 100 parts by weight of the urethane preparation component. More preferably, it is 8 to 40 parts by weight per 100 parts by weight of the urethane preparation component.

[0121] [Other configurations] The developing roller 11 used in the present invention may have intermediate layers such as adhesive layers or primer layers between the shaft 12 and the elastic layer 13, and between the elastic layer 13 and the coating layer 14. Of these intermediate layers, the electrical properties of the adhesive layer and primer layer provided between the elastic layer 13 and the coating layer 14 can be adjusted to adjust the electrical properties of the developing roller 11. This makes it possible to favorably adjust the development performance of the developing roller 11 as a developing roller. As the primer layer, a layer typically used as a primer layer for a developing roller can be used, but by forming a primer layer made of, for example, a urethane resin having an ester group, the development performance of the developing roller can be favorably maintained.

[0122] [Electrophotographic equipment] An embodiment of the electrophotographic apparatus according to the present invention will be described in detail below. The electrophotographic apparatus according to the present invention comprises the electrophotographic photosensitive member, charging means, exposure means, and developing means described above. The charging means charges the surface of the electrophotographic photosensitive member. The exposure means irradiates the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member. The developing means has toner and develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member. The developing means is the developing roller described above.

[0123] A tandem color electrophotographic apparatus will be described below as an example with reference to Fig. 5. Fig. 5 is a cross-sectional view showing an example of an electrophotographic apparatus. The electrophotographic apparatus 100 shown in FIG. 5 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing device 54. Hereinafter, unless there is a need to distinguish between them, each of the image forming units 40a, 40b, 40c, and 40d will be referred to as an image forming unit 40. The image forming unit 40 includes an image carrier 30, a charging device 42 as a charging means, an exposure device 44 as an exposure means, a developing device 46 as a developing means, and a transfer device 48 as a transfer means. The image carrier 30 is a photoreceptor (specifically, a single-layer photoreceptor 1). A recording medium P is located at the bottom of the electrophotographic apparatus. The image carrier 30 is provided at the center of the image forming unit 40. The image carrier 30 is provided rotatably in the direction of the arrow (counterclockwise in FIG. 5). Around the image carrier 30, a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48 are provided in this order from the upstream side in the rotation direction of the image carrier 30.

[0124] Toner images of multiple colors (for example, four colors: black, cyan, magenta, and yellow) are sequentially superimposed on the recording medium P on the transfer belt 50 by each of the image forming units 40a to 40d. The charging device 42 positively charges the surface (e.g., the peripheral surface) of the image carrier 30. When the image carrier 30 is a single-layer photoreceptor 1, the surface of the image carrier 30 is positively charged. The charging device 42 is, for example, a charging roller. The exposure device 44 irradiates the charged surface of the image carrier 30 with exposure light. That is, the exposure device 44 exposes the charged surface of the image carrier 30. As a result, an electrostatic latent image is formed on the surface of the image carrier 30. The electrostatic latent image is formed based on image data input to the electrophotographic apparatus 100. The developing device 46 supplies toner to the surface of the image carrier 30 and develops the electrostatic latent image into a toner image. The developing device 46 (for example, the surface of the developing device 46, more specifically, the circumferential surface of the developing device 46) is in contact with the surface of the image carrier 30. That is, the electrophotographic apparatus 100 employs a contact development method. The developing device 46 is, for example, a developing roller. When the developer is a one-component developer, the developing device 46 supplies toner, which is the one-component developer, to the electrostatic latent image formed on the image carrier 30. When the developer is a two-component developer, the developing device 46 supplies toner, which is the toner and carrier contained in the two-component developer, to the electrostatic latent image formed on the image carrier 30. In this way, the image carrier 30 carries a toner image.

[0125] The transfer belt 50 transports the recording medium P between the image carrier 30 and the transfer device 48. The transfer belt 50 is an endless belt. The transfer belt 50 is rotatable in the direction of the arrow (clockwise in FIG. 5). The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image carrier 30 to a transfer recipient. The transfer recipient is the recording medium P. When the toner image is transferred, the image carrier 30 is in contact with the recording medium P. In other words, the electrophotographic apparatus 100 employs a direct transfer method. The transfer device 48 is, for example, a transfer roller. The recording medium P onto which the toner image has been transferred by the transfer device 48 is transported by the transfer belt 50 to the fixing device 54. The fixing device 54 is, for example, a heating roller and / or a pressure roller. The unfixed toner image transferred by the transfer device 48 is heated and / or pressurized by the fixing device 54. The toner image is heated and / or pressurized, whereby the toner image is fixed to the recording medium P. As a result, an image is formed on the recording medium P.

[0126] Although an example of an electrophotographic apparatus has been described above, the electrophotographic apparatus is not limited to the electrophotographic apparatus 100 already described. While the electrophotographic apparatus 100 already described is a color electrophotographic apparatus, the electrophotographic apparatus may also be a monochrome electrophotographic apparatus. In this case, the electrophotographic apparatus may include, for example, only one image forming unit. Furthermore, while the electrophotographic apparatus 100 already described employs a tandem system, the electrophotographic apparatus may also employ, for example, a rotary system. While a charging roller has been used as the charging device 42, the charging device may also be a charging device other than a charging roller (e.g., a scorotron charger, a charging brush, or a corotron charger). Although the electrophotographic apparatus 100 already described employs a contact development system, the electrophotographic apparatus may also employ a non-contact development system. Although the electrophotographic apparatus 100 already described employs a direct transfer system, the electrophotographic apparatus may also employ an intermediate transfer system. When the electrophotographic apparatus employs an intermediate transfer system, the transfer target corresponds to an intermediate transfer belt. Although the image forming unit 40 already described in the electrophotographic apparatus does not include a cleaning member, the image forming unit may further include a cleaning member (e.g., a cleaning blade). Although the image forming unit 40 already described does not include a static eliminator, the image forming unit may further include a static eliminator.

[0127] [Process cartridge] Next, with continued reference to FIG. 5, an example of a process cartridge that can be used in the present invention will be described. The process cartridge corresponds to each of the image forming units 40a to 40d. The process cartridge includes an image carrier 30. The image carrier 30 is the photosensitive member of the first embodiment. In addition to the image carrier 30, the process cartridge further includes at least one selected from the group consisting of a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The process cartridge may further include a cleaning member and a static eliminator. The process cartridge is designed to be detachable from the electrophotographic apparatus 100. Therefore, the process cartridge is easy to handle, and can be easily and quickly replaced, including the image carrier 30, when the sensitivity characteristics of the image carrier 30 deteriorate. Above, a process cartridge including a photosensitive member has been described with reference to FIG. 5. [Example]

[0128] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following examples, "parts" are based on mass unless otherwise specified.

[0129] <Production of Polyester Resin> [Synthesis of resin (PAR-1)] The reaction vessel used was a three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel. The following materials were prepared: Monomer compound (BP-2): 41.0 mmol 2,6-dimethylphenol (DMP), a terminal blocking agent: 0.213 mmol Sodium hydroxide: 98 mmol Benzyltributylammonium chloride: 0.384 mmol These were placed in a reaction vessel, and the air in the reaction vessel was replaced with argon gas. 300 mL of water was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50°C for 1 hour. The contents of the reaction vessel were cooled to 10°C to obtain alkaline aqueous solution A1. Next, 32.0 mmol of dicarboxylic acid dichloride, which is a monomer compound (DC-1), was dissolved in 150 mL of chloroform, thereby obtaining a chloroform solution B1. Using a dropping funnel, chloroform solution B1 was slowly added dropwise to alkaline aqueous solution A1 over 110 minutes. The contents of the reaction vessel were stirred for 4 hours while maintaining the temperature (liquid temperature) of the contents of the reaction vessel at 15±5°C, allowing the polymerization reaction to proceed. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decanter to obtain an organic layer. Next, 400 mL of ion-exchanged water was added to an Erlenmeyer flask. The obtained organic layer was then added to the Erlenmeyer flask. Another 400 mL of chloroform and 2 mL of acetic acid were added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25°C) for 30 minutes. The upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed using a decanter to obtain an organic layer. Using a separatory funnel, the obtained organic layer was washed with ion-exchanged water (1 L). Washing with ion-exchanged water was repeated five times to obtain a water-washed organic layer. The washed organic layer was then filtered to obtain a filtrate. The obtained filtrate was slowly added dropwise to 1 L of methanol to obtain a precipitate. The precipitate was then filtered. The collected precipitate was dried in a vacuum for 12 hours at 70° C. As a result, a resin (PAR-1) with a viscosity average molecular weight of 35,000 was obtained.

[0130] [Synthesis of resin (PAR-2)] The reaction vessel used was a three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel. The following materials were prepared: Monomer compound (BP-5) 28.7 mmol Monomer compound (BP-2) 12.3 mmol 0.413 mmol of 2,6-dimethylphenol (DMP) as a terminal blocker 98 mmol of sodium hydroxide 0.384 mmol of benzyltributylammonium chloride These were placed in a reaction vessel, and the air in the reaction vessel was replaced with argon gas. 300 mL of water was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50°C for 1 hour. The contents of the reaction vessel were cooled to 10°C to obtain alkaline aqueous solution A2. Next, 20.8 mmol of the dicarboxylic acid dichloride of the monomer compound (DC-1) and 11.2 mmol of the dicarboxylic acid dichloride of the monomer compound (DC-4) were dissolved in 150 mL of chloroform, thereby obtaining a chloroform solution B2. Using a dropping funnel, chloroform solution B2 was slowly added dropwise to alkaline aqueous solution A2 over 110 minutes. The contents of the reaction vessel were stirred for 4 hours while maintaining the temperature (liquid temperature) of the contents of the reaction vessel at 15±5°C, allowing the polymerization reaction to proceed. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decanter to obtain an organic layer. Next, 400 mL of ion-exchanged water was added to an Erlenmeyer flask. The obtained organic layer was then added to the Erlenmeyer flask. Another 400 mL of chloroform and 2 mL of acetic acid were added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25°C) for 30 minutes. The upper layer (aqueous layer) of the contents of the Erlenmeyer flask was removed using a decanter to obtain an organic layer. Using a separatory funnel, the obtained organic layer was washed with 1 L of ion-exchanged water. Washing with ion-exchanged water was repeated five times to obtain a water-washed organic layer. The washed organic layer was then filtered to obtain a filtrate. The obtained filtrate was slowly added dropwise to 1 L of methanol to obtain a precipitate. The precipitate was then filtered. The collected precipitate was dried in a vacuum for 12 hours at a temperature of 70° C. As a result, a resin (PAR-2) with a viscosity average molecular weight of 55,000 was obtained.

[0131] [Synthesis of resins (PAR-3 to PAR-15)] The polyester resins were synthesized in the same manner as in the synthesis of resin (PAR-2), except that the relative ratio of bisphenol to dicarboxylic acid and the type and amount of end-capping agent were changed, to obtain polyester resins with the viscosity-average molecular weights shown in Table 1. The viscosity-average molecular weight of the polyester resin increased as the amount of end-capping agent decreased.

[0132] [Table 1]

[0133] The values listed for bisphenols in Table 1 indicate the molar ratio of each bisphenol monomer to the total molar amount of the two bisphenols. The values listed for dicarboxylic acids indicate the molar ratio of each dicarboxylic acid monomer to the total molar amount of the two dicarboxylic acids. PFH stands for 1H,1H-perfluoro-1-heptanol. The molecular weight indicates the viscosity average molecular weight.

[0134] <Production of electrophotographic photoreceptors> [Production of photoreceptor 1] The following materials were prepared: 2.0 parts by weight of Y-type titanyl phthalocyanine (CGM-1), a charge-generating material Hole transport material (H-11) 70.0 parts by weight ·Electron transport material (E-4) 50.0 parts by mass Binder resin (PAR-1) 100.0 parts by weight 500.0 parts by mass of tetrahydrofuran as a solvent These were mixed for 20 minutes using a rod-shaped ultrasonic oscillator to obtain a dispersion. The dispersion was filtered using a filter with 5 μm mesh to obtain a coating solution for the photosensitive layer. The coating solution for the photosensitive layer was applied to a conductive substrate (aluminum drum-shaped support) by dip coating and dried with hot air at 120°C for 50 minutes. In this way, a photosensitive layer (film thickness 30 μm) was formed on the conductive substrate, and photoreceptor 1 was obtained. (Analysis of resin components of photoreceptor 1) The polymer component recovered from the obtained photoreceptor 1 was dissolved in deuterated chloroform. 1 H-nuclear magnetic resonance analysis 1 H-NMR spectra were obtained. 1The H-NMR spectrum had peaks at 8.22±0.02, 7.18±0.02, 7.16±0.02, 7.10±0.02, 7.06±0.02, and 7.04±0.02 ppm. This confirmed that Photoreceptor 1 contained the structural units represented by Formula (1) and Formula (2). The molar ratio of the amounts of substance of the structural units represented by Formula (1) and Formula (2) was 1:1, as shown in Table 1, based on the integral ratio of the peaks.

[0135] [Production of photoreceptors 2 to 24] Photoreceptors 2 to 24 were manufactured using the same method as for manufacturing photoreceptor 1, except that the types of charge generation material (CGM), additive, hole transport material (HTM), electron transport material (ETM), and binder resin were changed. Table 2 shows the types of charge generation material, additive, hole transport material, electron transport material, and binder resin used. The amounts of each material used were the same as for manufacturing photoreceptor 1. (Analysis of resin components of photoreceptors 2 to 24) The polymer components recovered from the obtained photoreceptors 2 to 24 were dissolved in deuterated chloroform. 1 H-nuclear magnetic resonance analysis 1 H-NMR spectra were obtained. 1 The H-NMR spectrum showed peaks at 8.22±0.02, 7.18±0.02, 7.16±0.02, 7.10±0.02, 7.06±0.02, 7.04±0.02, 2.28±0.02, 2.20±0.02, 1.59±0.02, and 1.54±0.02 ppm. This confirmed that photoreceptors 2 to 24 contained structural units represented by formulas (1), (2), (4), and (5), respectively. Furthermore, the molar ratios of the amounts of substance of the structural units represented by formulas (1), (2), (4), and (5) were determined based on the integral ratios of the peaks, as shown in Table 1.

[0136] [Table 2]

[0137] <Developing roller manufacturing method> [Manufacturing of developing roller A] An electroless nickel-plated shaft (made of SUM22, diameter 10 mm, length 275 mm) was washed with ethanol, and its surface was coated with a silicone primer (product name "Primer No. 16" manufactured by Shin-Etsu Chemical Co., Ltd.). The primer-treated shaft was baked in a gear oven at 150°C for 10 minutes and then cooled at room temperature for at least 30 minutes, forming a primer layer on the outer surface of the shaft. Next, a silicone rubber composition for forming the elastic layer was prepared as follows: First, the following materials were prepared. 100 parts by weight of dimethylpolysiloxane (degree of polymerization 300) with both ends blocked with dimethylvinylsiloxy groups BET specific surface area of 110m 2 1 part by mass of hydrophobic treated fumed silica (trade name "R-972", manufactured by Nippon Aerosil Co., Ltd.) with an average particle size of 6 μm and a bulk density of 0.25 g / cm 3 40 parts by mass of diatomaceous earth (trade name "Oplite W-3005S", manufactured by Chuo Silica Co., Ltd.) 5 parts by weight of acetylene black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.) These were placed in a planetary mixer and mixed for 30 minutes, then passed through a three-roll mill once. This was then returned to the planetary mixer. Next, the next material was prepared. 2.1 parts by mass of methylhydrogenpolysiloxane (degree of polymerization 17, Si-H content 0.0060 mol / g) with Si-H groups at both ends and on the side chains 0.1 parts by mass of ethynylcyclohexanol ·Platinum catalyst (Pt concentration 1%) 0.1 part by mass These ingredients were added to a planetary mixer and stirred / deaerated / kneaded for 30 minutes to prepare an addition-curable liquid conductive silicone rubber composition. The prepared addition-curable liquid conductive silicone rubber composition was injection molded using a mold to form an elastic body made of rubber material on the outer surface of the shaft. In the injection molding, the addition-curable liquid conductive silicone rubber composition was heated at 120°C for 10 minutes to cure, and then secondary vulcanized at 200°C for 4 hours to form an elastic layer with an outer diameter of 16 mm.

[0138] Next, a resin composition for forming a coating layer was prepared as follows. First, the following materials were prepared: 35 parts by weight of acrylic polyol 46 parts by weight of hexamethylene diisocyanate (product name "Duranate E402-B80B", manufactured by Asahi Kasei Corporation) Dibutyltin dilaurate (Tokyo Chemical Industry Co., Ltd.) 0.03 parts by mass 4 parts by weight of small-diameter silica (average particle size 4.4 μm, product name "ACEMATT OK-607", manufactured by Evonik Degussa Co., Ltd.) 3 parts by mass of carbon black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.) as a conductivity enhancer 30 parts by weight of thinner These were mixed to obtain a urethane resin composition. Subsequently, the urethane resin composition was applied to the outer peripheral surface of the elastic layer by spray coating, and heated at 160°C for 30 minutes to form a coating layer with a thickness of 12 µm. In this way, a developing roller A including a shaft, an elastic layer, and a coating layer was manufactured.

[0139] [Manufacturing of developing roller B] Developing roller B was produced in the same manner as developing roller A, except that the coating layer was formed using the following resin composition. First, the following materials were prepared: Acrylic polyol 42 parts by weight 52 parts by weight of hexamethylene diisocyanate (product name "Duranate E402-B80B", manufactured by Asahi Kasei Corporation) Dibutyltin dilaurate (Tokyo Chemical Industry Co., Ltd.) 0.03 parts by mass 4 parts by weight of small-diameter silica (average particle size 4.4 μm, product name "ACEMATT OK-607", manufactured by Evonik Degussa Co., Ltd.) Carbon black (product name "Denka Black HS-100", manufactured by Denka Co., Ltd.) 3 parts by weight Pyridinium type {N-hydroxyethylpyridinium bis(trifluoromethasulfonyl)imide} (see structural formula below) 0.7 parts by mass [ka] 30 parts by weight of thinner These were mixed to obtain a urethane resin composition. Subsequently, the urethane resin composition was applied to the outer peripheral surface of the elastic layer by spray coating, and heated at 160°C for 30 minutes to form a coating layer with a thickness of 15 µm. In this way, developing roller B equipped with a shaft, an elastic layer, and a coating layer was manufactured.

[0140] [Manufacturing of developing roller C] Developing roller C was produced in the same manner as developing roller A, except that the coating layer was formed using the following resin composition. First, the following materials were prepared: Acrylic polyol 42 parts by weight 52 parts by weight of hexamethylene diisocyanate (product name "Duranate E402-B80B", manufactured by Asahi Kasei Corporation) Dibutyltin dilaurate (Tokyo Chemical Industry Co., Ltd.) 0.03 parts by mass 4 parts by weight of small-diameter silica (average particle size 4.4 μm, product name "ACEMATT OK-607", manufactured by Evonik Degussa Co., Ltd.) 10 parts by weight of cross-linked acrylic ester resin particles (trade name "Techpolymer AFX-8", manufactured by Sekisui Plastics Co., Ltd.) with a recovery rate of 20%, a 10% compressive strength of 0.4 MPa, and an average particle size of 8 μm Carbon black (product name "Denka Black HS-100", manufactured by Denka Co., Ltd.) 3 parts by weight 0.7 parts by mass of pyridinium-based {N-hydroxyethylpyridinium bis(trifluoromethasulfonyl)imide} (see structural formula above) 30 parts by weight of thinner These were mixed to obtain a resin composition. Subsequently, the urethane resin composition was applied to the outer peripheral surface of the elastic layer by spray coating, and heated at 160°C for 30 minutes to form a coating layer with a thickness of 15 µm. In this way, a developing roller C having a shaft, an elastic layer, and a coating layer was manufactured.

[0141] [Manufacturing of developing roller D] Developing roller D was produced in the same manner as developing roller A, except that the coating layer was formed using the following resin composition. First, the following materials were prepared: Acrylic polyol 42 parts by weight 52 parts by weight of hexamethylene diisocyanate (product name "Duranate E402-B80B", manufactured by Asahi Kasei Corporation) Dibutyltin dilaurate (Tokyo Chemical Industry Co., Ltd.) 0.03 parts by mass Carbon black (product name "Denka Black HS-100", manufactured by Denka Co., Ltd.) 3 parts by weight 30 parts by weight of thinner These were mixed to obtain a urethane resin composition. Subsequently, the urethane resin composition was applied to the outer peripheral surface of the elastic layer by spray coating, and heated at 160°C for 30 minutes to form a coating layer with a thickness of 13 µm. In this way, a developing roller D including a shaft, an elastic layer, and a coating layer was manufactured.

[0142] [evaluation] Using each of the photoreceptors (single-layer type photoreceptors) and developing rollers manufactured as described above, filming resistance, scattering, and transfer efficiency were evaluated by the methods described below. A modified Brother HL-5200 monochrome laser printer was used as the electrophotographic device. A high-voltage power supply control system (trade name: Model 615-3, manufactured by Trek) was used as the power source for supplying power to the corona charger from outside the printer. The electrophotographic photosensitive member of the drum unit in the cartridge for this printer was removed, and each of the manufactured photosensitive members was installed in its place. Each of the manufactured developing rollers was also installed in the electrophotographic device. The toner in the developing means of the electrophotographic device was a positively charged toner.

[0143] <Evaluation of filming resistance> Using an electrophotographic device equipped with the manufactured developing roller, 10,000 sheets were printed under conditions of a temperature of 23°C and a humidity of 55%RH. After the developer adhering to the surface of the developing roller was sucked, the mass transferred to a filming weight measuring jig was measured. Filming was evaluated based on the mass of the transferred developer according to the following criteria. In this test, a filming amount of C or higher was considered to be acceptable. A: The mass of the transferred developer is 0 mg or more and less than 0.02 mg. B: The mass of the transferred developer is 0.02 mg or more and less than 0.04 mg. C: The mass of the transferred developer is 0.04 mg or more and less than 0.06 mg. D: The mass of the transferred developer is 0.06 mg or more.

[0144] <Toner scattering evaluation> The evaluation of toner scattering was carried out in a room temperature and high humidity environment (temperature 25.0°C, relative humidity 80%). The evaluation images were printed on Canon A4 size OceRedLabel paper (basis weight 80 g / m 2 An image of a horizontal line pattern was output on a 1000x magnifying glass, with 4-dot horizontal lines printed every 176 dots. The print mode was set to 2 sheets per job, with the machine pausing between jobs before the next job began. A total of 1000 images were output, and a toner scattering evaluation was carried out. The evaluation was carried out by observing the 1000th image using a 25x magnifying glass. The criteria for judging splashing are as follows: When the splashing rating was C or higher, it was judged to be good. A: When observed with a 25x magnifying glass, no toner scattering occurred. B: When observed with a 25x loupe, toner scattering was observed in several places around the image. C: When observed with a 25x loupe, a large amount of toner scattering was observed around the image. D: Although not at a level that poses a practical problem, toner scattering is visually observed. E: Toner scattering is clearly observed visually.

[0145] <Transfer efficiency> Using a chart capable of forming multiple 1cm x 20cm images, the density when the remaining part of the photoreceptor was taped and pasted onto paper was defined as D1, and the density when the part transferred onto the paper and then taped was defined as D2. The density was calculated using the following formula. Transfer efficiency (%) = {D2 / (D1+D2)} × 100 The difference in transfer efficiency between the initial state and after passing 15,000 sheets under a low temperature and low humidity environment (L / L; 10°C / 14% RH) was evaluated according to the following criteria. A: Less than 2% is good. B: 2% or more and less than 4% and no practical problems. C: 4% or more and less than 6% and no practical problem. D: 6% or more and less than 8% and problematic in practical use. E: 8% or more is problematic in practical use. The evaluation results are shown in Table 3.

[0146] [Table 3]

[0147] In Examples 1 to 22, which used a photoreceptor and developing roller containing the polyester resin used in the present invention, filming was suppressed and the quality of the output image was maintained initially and throughout repeated use. On the other hand, in the comparative examples, both filming resistance and suppression of transfer defects were not achieved through repeated use.

[0148] The disclosure according to an embodiment of the present invention includes the following configuration. (Configuration 1) electrophotographic photoreceptors, a charging means for charging the surface of the electrophotographic photosensitive member; an exposure unit for irradiating the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; and a developing means having a toner, and developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member; An electrophotographic apparatus having the electrophotographic photoreceptor has a single-layer photosensitive layer containing a charge generating material, a hole transporting material, an electron transporting material, and a first binder resin; the photosensitive layer contains, as the first binder resin, a polyester resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), [ka] [ka] the developing means is a developing roller having a shaft, an elastic layer provided on the outer periphery of the shaft, and a coating layer provided on the outer periphery of the elastic layer, The coating layer contains a second binder resin and silica particles. Electrophotographic apparatus characterized by: (Configuration 2) 2. The electrophotographic apparatus according to claim 1, wherein the polyester resin further comprises a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5): [ka] [ka] (Configuration 3) The electrophotographic device according to Structure 2, wherein, in the polyester resin, when the ratio of the molar amount of substance of the structural unit represented by Formula (1) to the sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M1 and the ratio of the molar amount of substance of the structural unit represented by Formula (4) to the sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M4, M4 / (M1+M4) is 0.30 or more and 0.70 or less. (Configuration 4) The electrophotographic device according to Structure 2, wherein, in the polyester resin, when the ratio of the molar amount of substance of the structural unit represented by Formula (2) to the sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M2 and the ratio of the molar amount of substance of the structural unit represented by Formula (5) to the sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M5, M2 / (M2+M5) is 0 or more and 0.50 or less. (Configuration 5) The electrophotographic device according to any one of Structures 1 to 4, wherein M1 / MC is 0.50 or more, where MC is the sum of the molar amounts of the structural units derived from dicarboxylic acids constituting the polyester resin, and M1 is the molar amount of the structural unit represented by formula (1). (Configuration 6) 6. The electrophotographic apparatus according to any one of Configurations 1 to 5, wherein the content of the polyester resin is 50% by mass or more with respect to the total mass of the first binder resin. (Configuration 7) The electrophotographic device according to any one of Configurations 1 to 6, wherein the electron transport material contains at least one compound selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), a compound represented by the following formula (13), a compound represented by the following formula (14), a compound represented by the following formula (15), and a compound represented by the following formula (16): [ka] [ka] [ka] [ka] [ka] [ka] [ka] (Q in Eq. (10) 1 and Q 2 , Q in Eq. (11) 11 , Q 12 , and Q 13 , Q in Eq. (12) 21 , Q 22 , Q 23 , and Q 24 , Q in Eq. (13) 31 and Q 32 , Q in Eq. (14) 41 , Q 42 , Q 43 , and Q 44 , Q in Eq. (15) 51 , Q 52 , Q 53 , Q 54 , Q 55 , and Q 56 , and Q in equation (16) 61 and Q 62 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom; and Y in formula (15) 1 and Y 2 each independently represents an oxygen atom or a sulfur atom. (Configuration 8) The electrophotographic device according to Configuration 7, wherein the electron transport material comprises at least one compound selected from the group consisting of a compound represented by the following formula (E-1), a compound represented by the following formula (E-2), a compound represented by the following formula (E-3), a compound represented by the following formula (E-4), a compound represented by the following formula (E-5), a compound represented by the following formula (E-6), a compound represented by the following formula (E-7), and a compound represented by the following formula (E-8). [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] (Configuration 9) The electrophotographic device according to any one of Configurations 1 to 8, wherein the hole transport substance includes at least one compound selected from the group consisting of a compound represented by the following formula (20), a compound represented by the following formula (21), a compound represented by the following formula (22), a compound represented by the following formula (23), and a compound represented by the following formula (24): [ka] [ka] [ka] [ka] [ka] (In formula (20), R 11 , R 12 , R 13 , and R 14 each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, 1 , a 2 , a 3 , and a 4 each independently represents an integer of 0 to 5, and in formula (21), R 21 , R 22, and R 23 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 24 , R 25 , and R 26 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; b 1 , b 2 , and b 3 each independently represents 0 or 1, and in formula (22), R 31 , R 32 , and R 33 each independently represents an alkyl group having 1 to 6 carbon atoms, and R 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, and d 1 , d 2 , and d 3 each independently represents an integer of 0 to 5, and in formula (23), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group; R 47 and R 48 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group; e 1 , e 2 , e 3 , and e 4 each independently represents an integer of 0 to 5, 5 and e 6 each independently represents an integer of 0 to 4, 7 and e 8 each independently represents 0 or 1, and in formula (24), R 50 and R 51 each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group; R 52 , R 53 , R 54 , R 55 , R 56 , R 57 , and R 58each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms; 1 and f 2 each independently represents an integer of 0 to 2, 3 and f 4 each independently represents an integer of 0 or more and 5 or less. (Configuration 10) The electrophotographic device according to Structure 9, wherein the hole transport substance comprises at least one compound selected from the group consisting of a compound represented by the following formula (H-1), a compound represented by the following formula (H-2), a compound represented by the following formula (H-3), a compound represented by the following formula (H-4), a compound represented by the following formula (H-5), a compound represented by the following formula (H-6), a compound represented by the following formula (H-7), a compound represented by the following formula (H-8), a compound represented by the following formula (H-9), a compound represented by the following formula (H-10), and a compound represented by the following formula (H-11). [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] (Configuration 11) 11. The electrophotographic apparatus according to any one of Configurations 1 to 10, wherein the charge generating material contains titanyl phthalocyanine. (Configuration 12) 12. The electrophotographic apparatus according to any one of Configurations 1 to 11, wherein the photosensitive layer contains a compound represented by the following formula (T-1): [ka] (Configuration 13) 13. The electrophotographic apparatus according to any one of configurations 1 to 12, wherein the silica particles have an average particle size of 10 nm or more and 5 μm or less. (Configuration 14) the coating layer contains a hydroxyl group-containing ionic liquid that does not contain an ether group, 14. The electrophotographic apparatus according to any one of configurations 1 to 13, wherein the ionic liquid is at least one ionic liquid selected from the group consisting of an aliphatic amine-based ionic liquid, a pyridinium-based ionic liquid, and an imidazolium-based ionic liquid. (Configuration 15) 15. The electrophotographic apparatus according to claim 14, wherein the content of the ionic liquid in the coating layer is 0.1 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the content of the second binder resin. (Configuration 16) 16. The electrophotographic apparatus according to any one of Configurations 1 to 15, wherein the coating layer contains at least one resin particle selected from the group consisting of crosslinked acrylic acid ester resin particles and crosslinked methacrylic acid ester resin particles. (Configuration 17) 17. The electrophotographic apparatus according to claim 16, wherein the at least one resin particle selected from the group consisting of crosslinked acrylic ester resin particles and crosslinked methacrylic ester resin particles has an average particle size of 1 μm or more and 15 μm or less. [Explanation of symbols]

[0149] 1: Single-layer photoreceptor 2:Support 3: Photosensitive layer 4: Undercoat layer 5:Protective layer 11: Developing roller 12: Shaft 13: Elastic layer 14: Covering layer 30: Image carrier 42: Charging device 44: Exposure equipment 46: Developing device 48: Transcription device 100: Electrophotographic device

Claims

1. electrophotographic photoreceptors, a charging means for charging the surface of the electrophotographic photosensitive member; an exposure unit for irradiating the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; and an electrophotographic apparatus having a developing unit which has a toner and develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member, the electrophotographic photoreceptor has a single-layer photosensitive layer containing a charge generating material, a hole transporting material, an electron transporting material, and a first binder resin; the photosensitive layer contains, as the first binder resin, a polyester resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2), 【Chemical 1】 【Chemistry 2】 the developing means is a developing roller having a shaft, an elastic layer provided on the outer periphery of the shaft, and a coating layer provided on the outer periphery of the elastic layer, the coating layer contains a second binder resin and silica particles; Electrophotographic apparatus characterized by:

2. 2. The electrophotographic apparatus according to claim 1, wherein the polyester resin further comprises a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5). 【Chemistry 3】 【Chemistry 4】

3. In the polyester resin, when M1 is a ratio of the molar amount of the structural unit represented by formula (1) to the sum of the molar amounts of the structural units constituting the polyester resin, and M4 is a ratio of the molar amount of the structural unit represented by formula (4), M4 / (M1+M4) is 0.30 or more and 0.70 or less; 3. The electrophotographic apparatus according to claim 2.

4. 3. The electrophotographic device according to claim 2, wherein, in the polyester resin, when a ratio of the molar amount of substance of the structural unit represented by formula (2) to a sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M2 and a ratio of the molar amount of substance of the structural unit represented by formula (5) to a sum of the molar amounts of substance of the structural units constituting the polyester resin is defined as M5, M2 / (M2+M5) is 0 or more and 0.50 or less.

5. 2. The electrophotographic device according to claim 1, wherein M1 / MC is 0.50 or more, where MC is the sum of the molar amounts of the structural units derived from dicarboxylic acids constituting the polyester resin, and M1 is the molar amount of the structural unit represented by formula (1).

6. 2. The electrophotographic apparatus according to claim 1, wherein a content ratio of the polyester resin to a total mass of the first binder resin is 50% by mass or more.

7. The electrophotographic device according to any one of claims 1 to 6, wherein the electron transport material comprises at least one compound selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), a compound represented by the following formula (13), a compound represented by the following formula (14), a compound represented by the following formula (15), and a compound represented by the following formula (16): 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 (Q in formula (10) １ and Q ２ , Q in formula (11) １１ , Q １２ , and Q １３ , Q in formula (12) ２１ , Q ２２ , Q ２３ , and Q ２４ , Q in formula (13) ３１ and Q ３２ , Q in formula (14) ４１ , Q ４２ , Q ４３ , and Q ４４ , Q in formula (15) ５１ , Q ５２ , Q ５３ , Q ５４ , Q ５５ , and Q ５６ , and Q in formula (16) ６１ and Q ６２ each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or an aryl group having from 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having from 1 to 6 carbon atoms and a halogen atom; and Y in formula (15) １ and Y ２ each independently represents an oxygen atom or a sulfur atom.

8. 8. The electrophotographic device according to claim 7, wherein the electron transport material comprises at least one compound selected from the group consisting of a compound represented by the following formula (E-1), a compound represented by the following formula (E-2), a compound represented by the following formula (E-3), a compound represented by the following formula (E-4), a compound represented by the following formula (E-5), a compound represented by the following formula (E-6), a compound represented by the following formula (E-7), and a compound represented by the following formula (E-8): 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 【Chemistry 17】 【Chemistry 18】 【Chemistry 19】

9. The electrophotographic device according to any one of claims 1 to 6, wherein the hole transport substance includes at least one compound selected from the group consisting of a compound represented by the following formula (20), a compound represented by the following formula (21), a compound represented by the following formula (22), a compound represented by the following formula (23), and a compound represented by the following formula (24): 【Chemistry 20】 【Chemical 21】 【Chemical 22】 【Chemical 23】 【Chemistry 24】 (In formula (20), R １１ , R １２ , R １３ , and R １４ each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; １ , a ２ , a ３ , and a ４ each independently represents an integer of 0 to 5, and in formula (21), R ２１ , R ２２ , and R ２３ each independently represents an alkyl group having 1 to 6 carbon atoms; R ２４ , R ２５ , and R ２６ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; １ , b ２ , and b ３ each independently represents 0 or 1, and in formula (22), R ３１ , R ３２ , and R ３３ each independently represents an alkyl group having 1 to 6 carbon atoms; R ３４ represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom; d １ , d ２ , and d ３ each independently represents an integer of 0 to 5, and in formula (23), R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , and R ４６ each independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group; R ４７ and R ４８ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group; e １ , e ２ , e ３ , and e ４ each independently represents an integer of 0 to 5, ５ and e ６ each independently represents an integer of 0 to 4, ７ and e ８ each independently represents 0 or 1, and in formula (24), R ５０ and R ５１ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group; R ５２ , R ５３ , R ５４ , R ５５ , R ５６ , R ５７ , and R ５８ each independently represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having from 1 to 6 carbon atoms; １ and f ２ each independently represents an integer of 0 to 2, ３ and f ４ each independently represents an integer of 0 or more and 5 or less.

10. The electrophotographic device according to claim 9, wherein the hole transport substance comprises at least one compound selected from the group consisting of a compound represented by the following formula (H-1), a compound represented by the following formula (H-2), a compound represented by the following formula (H-3), a compound represented by the following formula (H-4), a compound represented by the following formula (H-5), a compound represented by the following formula (H-6), a compound represented by the following formula (H-7), a compound represented by the following formula (H-8), a compound represented by the following formula (H-9), a compound represented by the following formula (H-10), and a compound represented by the following formula (H-11). 【Chemistry 25】 【Chemical Formula 26】 【Chemical 27】 【Chemical 28】 【Chemical formula 29】 【Chemistry 30】 【Chemical 31】 【Chemical 32】 ​ 【Chemical 34】 【Chemical 35】

11. 7. The electrophotographic apparatus according to claim 1, wherein the charge generating material comprises titanyl phthalocyanine.

12. 7. The electrophotographic apparatus according to claim 1, wherein the photosensitive layer contains a compound represented by the following formula (T-1): 【Chemical 36】

13. 7. The electrophotographic apparatus according to claim 1, wherein the silica particles have an average particle size of 10 nm or more and 5 μm or less.

14. the coating layer contains a hydroxyl group-containing ionic liquid that does not contain an ether group, 7. The electrophotographic apparatus according to claim 1, wherein the ionic liquid is at least one ionic liquid selected from the group consisting of an aliphatic amine-based ionic liquid, a pyridinium-based ionic liquid, and an imidazolium-based ionic liquid.

15. The electrophotographic apparatus according to claim 14 , wherein the content of the ionic liquid in the coating layer is 0.1 parts by mass or more and 10 parts by mass or less when the content of the second binder resin is 100 parts by mass.

16. 7. The electrophotographic apparatus according to claim 1, wherein the coating layer contains at least one resin particle selected from the group consisting of crosslinked acrylic ester resin particles and crosslinked methacrylic ester resin particles.

17. 17. The electrophotographic apparatus according to claim 16, wherein the at least one resin particle selected from the group consisting of crosslinked acrylic ester resin particles and crosslinked methacrylic ester resin particles has an average particle size of 1 μm or more and 15 μm or less.

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