Electrophotographic photoreceptor, process cartridge, and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor that has improved image characteristics.SOLUTION: An electrophotographic photoreceptor has a support, an electron transport layer formed on the support, a charge generating layer formed immediately above the electron transport layer, and a hole transport layer formed on the charge generating layer. The charge generating layer contains butyral resin, and the electron transport layer contains a polymer having a structure represented by the formula (1) in the specification.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The electron transport layer is required to prevent injection of positive charges from the conductive substrate while allowing negative charges generated upon light irradiation to flow to the conductive substrate, thereby maintaining charging ability. As a technique for controlling the behavior of charges in this way, a technique of incorporating an electron transport material into the electron transport layer is known. For example, Patent Documents 1 and 2 disclose a technique of incorporating a perylene diimide compound derivative into the electron transport layer to improve the light / dark potential characteristics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,371,492 [Patent Document 2] Special Publication No. 2009-505156 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of the studies conducted by the present inventors, it was found that there is still room for improvement in the above-mentioned conventional techniques with respect to suppressing the occurrence of image defects. An object of the present invention is to provide an electrophotographic photoreceptor having improved image characteristics, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor. [Means for solving the problem]

[0005] As a result of intensive research, the inventors have found that by incorporating a compound having a specific structure into a photosensitive layer, it is possible to improve the adhesion of the photoreceptor and achieve a high level of suppression of the occurrence of image defects. That is, the present invention provides an electrophotographic photoreceptor having a support, an electron transport layer formed on the support, a charge generation layer formed on the electron transport layer, and a hole transport layer formed on the charge generation layer, characterized in that the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure selected from structures represented by any one of formulas (1) and (4) below. [ka] (In formula (1), R 1 R represents a single bond or an unsubstituted phenylene group. 2 and R 11 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 3 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, a methoxy group, a cyano group, or a halogen atom.

[0006] The polymer having the structure represented by the formula (1) can be obtained from a composition containing a compound having an oxazoline group represented by the following formula (2) and a compound having a carboxy group represented by the following formula (3). [ka] [ka] (In formula (2), R 1 is R in the formula (1). 1 In formula (3), R 2 ~R 11 are R in the above formula (1), 2 ~R 11 is equivalent to [ka] (In formula (4), R 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24 - (R 24 represents a single bond or an unsubstituted phenylene group. 13 , R 22 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 14 ~R 21 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom.

[0007] The polymer having the structure represented by formula (4) can be obtained from a composition containing a compound having an oxazoline group represented by formula (5) below and a compound having a carboxy group represented by formula (6) below. [ka] [ka] (In formula (5), R 12 is R in the above formula (4). 12 In formula (6), R 13 ~R22 are R in the above formula (4), 13 ~R 22 is equivalent to

[0008] According to another aspect of the present invention, there is provided an electrophotographic process cartridge which integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and is detachably attachable to the main body of the electrophotographic apparatus. According to another aspect of the present invention, there is provided an electrophotographic apparatus having the above electrophotographic photoreceptor, an exposure means, a charging means, a developing means, and a transfer means. Effect of the Invention

[0009] According to the present invention, it is possible to provide an electrophotographic photoreceptor in which the occurrence of image defects is suppressed, and a process cartridge and an electrophotographic apparatus each having the electrophotographic photoreceptor. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The electrophotographic photoreceptor of the present invention has a support, an electron transport layer formed on the support, a charge generation layer formed on the electron transport layer, and a hole transport layer formed on the charge generation layer, characterized in that the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure selected from structures represented by any one of the following formulas (1) and (4): [ka] (In formula (1), R 1 R represents a single bond or an unsubstituted phenylene group. 2 and R 11R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 3 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, a methoxy group, a cyano group, or a halogen atom. [ka] (In formula (4), R 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24 - (R 24 represents a single bond or an unsubstituted phenylene group. 13 , R 22 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 14 ~R 21 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom.

[0012] The present invention further relates to an electrophotographic process cartridge which integrally supports the above electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and is detachably mountable to the main body of the electrophotographic apparatus. The present invention further relates to an electrophotographic apparatus having the above electrophotographic photoreceptor, an exposure means, a charging means, a developing means, and a transfer means.

[0013] The present inventors believe that the mechanism by which the above technical problems can be solved with such a configuration is as follows. Since the perylene diimide structure is highly planar and rigid, it has low adhesion to other layers, and may cause minute peeling from other layers due to stress applied during repeated image output, resulting in image defects. In contrast, the amino ester structure contained in the compound of the present invention has amino and ester groups that are highly polar and have strong interactions with other layers, and furthermore, these groups are bonded with flexible alkyl chains, which is a structure advantageous for adhesion (note that the amino group has a structure (NH) having a hydrogen atom covalently bonded to a highly electronegative N atom, and the ester group has an ether structure (-O-) having an unshared electron pair). Therefore, it is believed that the adhesion to other layers is high and micro-peeling is unlikely to occur even during repeated image output, reducing image defects.

[0014] [Electrophotographic photoreceptor] The electrophotographic photoreceptor of the present invention has a support, an electron transport layer formed on the support, a charge generation layer formed directly on the electron transport layer, and a hole transport layer formed on the charge generation layer. The method for producing the electrophotographic photoreceptor of the present invention includes a method of preparing the coating liquid for each layer described later, coating the layers in the desired order, and drying the liquid. 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 viewpoint of efficiency and productivity. Each layer will be described below.

[0015] <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 a cylinder, a belt, a sheet, or the like. Among them, a cylindrical support is preferable. 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, or a glass. Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among them, an aluminum support using aluminum is preferable. Furthermore, the resin or glass may be made conductive by a process such as mixing with or coating with a conductive material.

[0016] <Conductive layer> In the electrophotographic photoreceptor of the present invention, a conductive layer may be provided on the support. By providing the conductive layer, scratches and irregularities on the support surface can be concealed and light reflection on the support surface can be controlled. The conductive layer preferably contains conductive particles and a resin. The conductive particles may be made of a material such as metal oxide, metal, or carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc.

[0017] Among these, it is preferable to use metal oxides as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide. When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof. The conductive particles may have a laminated structure having a core particle and a coating layer that covers the core particle. Examples of the core particle include titanium oxide, barium sulfate, zinc oxide, etc. Examples of the coating layer include metal oxides such as tin oxide. When a metal oxide is used as the conductive particles, the volume average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0018] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0019] The average thickness of the conductive layer is preferably from 1 μm to 50 μm, and particularly preferably from 3 μm to 40 μm. The conductive layer can be formed by preparing a coating solution for the conductive layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of the dispersion method for dispersing the conductive particles in the coating solution for the conductive layer include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0020] <Electron transport layer> The electrophotographic photoreceptor of the present invention has an electron transport layer formed on a support. An electron transport layer is provided between the photosensitive layer and the support. The electron transport layer contains a compound having a structure selected from the structures represented by the following formula (1) and formula (4). [ka] (In formula (1), R 1R represents a single bond or an unsubstituted phenylene group. 2 and R 11 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 3 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, a methoxy group, a cyano group, or a halogen atom.

[0021] R in the above formula (1) 1 is a single bond or an unsubstituted phenylene group, and R 2 and R 11 are each independently an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms (provided that the substituent on the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group), an unsubstituted phenylene group, a substituted phenylene group (provided that the substituent on the substituted phenylene group is at least one group selected from the group consisting of alkyl groups having 1 to 3 carbon atoms and halogen atoms), or a benzylene group. 3 ~R 10 are each independently a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. [ka] (In formula (4), R 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24 - (R 24 represents a single bond or an unsubstituted phenylene group. 13 , R 22R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 14 ~R 21 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom.

[0022] R in the above formula (4) 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24 - (R 24 R represents a single bond or an unsubstituted phenylene group. 13 , R 22 are each independently an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group (provided that the substituent of the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group), an unsubstituted phenylene group, a substituted phenylene group (provided that the substituent of the substituted phenylene group is at least one group selected from the group consisting of alkyl groups having 1 to 3 carbon atoms and halogen atoms), or a benzylene group. 14 ~R 21 are each preferably independently a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. 13 and R 22 is considered to be a phenylene group substituted with an alkyl group having one carbon atom.

[0023] The content of the polymer having the structure represented by formula (1) or formula (4) in the electron transport layer is preferably 50% by mass or more based on the total mass of the electron transport layer, thereby improving the image characteristics of the electrophotographic photoreceptor.

[0024] Specific examples of the compound represented by formula (1) are shown in Tables 1 to 3 below, and specific examples of the compound represented by formula (4) are shown in Tables 4 to 6 below.

[0025] [Table 1]

[0026] [Table 2]

[0027] [Table 3]

[0028] [Table 4]

[0029] [Table 5]

[0030] [Table 6]

[0031] The compound having the structure represented by formula (1) can be synthesized by reacting a compound having an oxazoline group represented by formula (2) below with a compound having a carboxy group represented by formula (3) below. The polymer having the structure represented by formula (1) is preferably a polymer of a composition containing a compound having an oxazoline group represented by formula (2) below and a compound having a carboxy group represented by formula (3) below. [ka] [ka] (In formula (2), R 1 is R in the formula (1). 1 In formula (3), R 2 ~R 11 are R in the above formula (1), 2 ~R 11 is equivalent to

[0032] The compound having the structure represented by formula (4) can be synthesized by reacting a compound having an oxazoline group represented by formula (5) below with a compound having a carboxy group represented by formula (6) below. The polymer having the structure represented by formula (4) is preferably a polymer of a composition containing a compound having an oxazoline group represented by formula (5) below and a compound having a carboxy group represented by formula (6) below. [ka] [ka] (In formula (5), R 12 is R in the above formula (4). 12 In formula (6), R 13 ~R 22 are R in the above formula (4), 13 ~R 22 is equivalent to

[0033] [Other resins] In addition to the compound used in the present invention, the electron transport layer may contain other substances to improve film-forming properties and electrical properties, such as resins, organic particles, inorganic particles, leveling agents, etc. However, the content of these substances in the electron transport layer is preferably less than 50% by mass, more preferably less than 20% by mass, based on the total mass of the electron transport layer.

[0034] The compounds used in the present invention were identified by the following methods. ·Mass spectrometry A matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (MALDI-TOF MS: Ultraflex, manufactured by Bruker Daltonics, Inc.) was used. The conditions were acceleration voltage: 20 kV, mode: Reflector, and molecular weight standard: fullerene C60. The molecular weight was confirmed from the peak top value obtained.

[0035] <Photosensitive layer> In the electrophotographic photoreceptor of the present invention, the photosensitive layer may be a single layer type containing both a charge generating material and a hole transporting material, or may be a laminate type in which a charge generating layer containing a charge generating material and a hole transporting layer containing a hole transporting material are laminated. The laminated charge generating layer and hole transport layer will be described below.

[0036] <Charge generation layer> The electrophotographic photoreceptor of the present invention has a charge generating layer formed directly on an electron transporting layer. The charge generating layer preferably contains a charge generating substance and a binder resin. Examples of the charge generating material include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, titanyl phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. When a titanyl phthalocyanine pigment is used as the charge generating material, it is preferable that the titanyl phthalocyanine pigment has crystal particles of a crystal type that shows peaks at Bragg angles 2θ of 9.8°±0.3° and 27.1°±0.3° in an X-ray diffraction spectrum using CuKα radiation.

[0037] The powder X-ray diffraction measurement of the phthalocyanine pigment contained in the electrophotographic photoreceptor of the present invention was carried out under the following conditions. (Powder X-ray diffraction measurement) Measuring equipment used: Rigaku Electric Co., Ltd., X-ray diffraction device RINT-TTRII X-ray tube:Cu X-ray wavelength: Kα1 Tube voltage: 50KV Tube current: 300mA Scan method: 2θ scan Scan speed: 4.0° / min Sampling interval: 0.02° Start angle 2θ: 5.0° Stop angle 2θ: 35.0° Goniometer: Rotor horizontal goniometer (TTR-2) Attachment: Capillary rotating sample stage Filter: None Detector: Scintillation counter Incident Monochrome: Use Slit: Variable slit (parallel beam method) Counter monochromator: Not used Divergence slit: open Divergence vertical limit slit: 10.00mm Scattering slit: open Receiving slit: open

[0038] Examples of the binder resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, and polyvinyl chloride resin. Among these, polyvinyl butyral resin (butyral resin) is more preferable. In the electrophotographic photoreceptor of the present invention, the charge generating layer contains a butyral resin. The content of the butyral resin in the charge generating layer is preferably 15% by mass or more based on the total mass of the charge generating layer. Butyral resin has a hydroxyl group structure (OH) having a hydrogen atom covalently bonded to a highly electronegative O atom, and an ether structure (-O-) having an unshared electron pair, with these structures being linked via an alkylene chain. Since the butyral resin has a structure similar to the amino ester structure contained in the electron transport layer of the present invention, it has improved adhesion.

[0039] The charge generating layer may further contain additives such as an antioxidant and an ultraviolet absorbing agent, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds. The average thickness of the charge generating layer is preferably from 0.07 μm to 1 μm, and more preferably from 0.1 μm to 0.3 μm. The charge generating layer can be formed by preparing a coating solution for the charge generating layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0040] <Hole transport layer> The electrophotographic photoreceptor of the present invention has a hole transport layer formed on the charge generating layer. The hole transport layer preferably contains a hole transport substance and a resin. Examples of hole transport substances include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred. The content of the hole transport material in the hole transport layer is preferably from 25% by mass to 70% by mass, and more preferably from 30% by mass to 55% by mass, based on the total mass of the hole transport layer.

[0041] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among these, polycarbonate resin and polyester resin are preferable. As the polyester resin, polyarylate resin is particularly preferable. The content ratio (mass ratio) of the hole transport substance to the resin is preferably from 4:10 to 20:10, and more preferably from 5:10 to 12:10.

[0042] The hole transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles. The average thickness of the hole transport layer is preferably from 5 μm to 50 μm, more preferably from 8 μm to 40 μm, and particularly preferably from 10 μm to 30 μm.

[0043] The hole transport layer can be formed by preparing a coating solution for the hole transport layer containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0044] <Protective layer> In the present invention, a protective layer may be provided on the hole transport layer. By providing the protective layer, durability can be improved. The protective layer preferably contains conductive particles and / or a hole transport substance, and a resin. The conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide. Examples of the hole transport substance include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred.

[0045] Examples of the resin include polyester resin, acrylic resin, phenoxy resin, polycarbonate resin, polystyrene resin, phenol resin, melamine resin, epoxy resin, etc. Among them, polycarbonate resin, polyester resin, and acrylic resin are preferable. The protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the reaction include thermal polymerization, photopolymerization, and radiation polymerization. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an acryloyl group and a methacryloyl group. A material having a charge transport function may be used as the monomer having a polymerizable functional group.

[0046] The protective layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, abrasion resistance improvers, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles. The average thickness of the protective layer is preferably from 0.5 μm to 10 μm, and more preferably from 1 μm to 7 μm. The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating solution. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0047] [Process cartridges, electrophotographic devices] It is preferable that the process cartridge according to one embodiment of the present invention integrally supports the electrophotographic photosensitive member described above and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and is detachably attachable to the main body of the electrophotographic apparatus. Moreover, an electrophotographic apparatus according to one aspect of the present invention preferably comprises the electrophotographic photosensitive member described above, an image exposure unit, a charging unit, a developing unit, and a transfer unit. FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member.

[0048] A cylindrical electrophotographic photoreceptor 1 is driven to rotate around an axis 2 at a predetermined peripheral speed in the direction of the arrow. The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by a charging means 3. Although the figure shows a roller charging method using a roller-type charging member, a corona charging method, a proximity charging method, an injection charging method, or other charging methods may be adopted. Exposure light 4 is irradiated from an exposure means (not shown) onto the charged surface of the electrophotographic photoreceptor 1, and an electrostatic latent image corresponding to the target image information is formed. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in a developing means 5, and a toner image is formed on the surface of the electrophotographic photoreceptor 1. The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to a transfer material 7 by a transfer means 6. The transfer material 7 to which the toner image has been transferred is transported to a fixing means 8, where the toner image is fixed, and the transfer material is printed out outside the electrophotographic device. The electrophotographic device may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. The cleaning means 9 is preferably a cleaning blade having a urethane resin. Alternatively, a so-called cleanerless system may be used in which the above-mentioned deposits are removed by a developing means or the like without providing a separate cleaning means 9. The electrophotographic apparatus may have a charge eliminating mechanism that eliminates charge on the surface of the electrophotographic photoreceptor 1 by pre-exposure light 10 from a pre-exposure means (not shown). Also, in order to mount and remove the process cartridge 11 according to one embodiment of the present invention to and from the main body of the electrophotographic image forming apparatus, a guide means 12 such as a rail may be provided. The electrophotographic photoreceptor according to one embodiment of the present invention can be used in electrophotographic image forming apparatuses such as laser beam printers, LED printers, copiers, facsimiles, and multifunction machines thereof. EXAMPLES

[0049] 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 without departing from the gist of the present invention. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0050] [Synthesis examples of compounds] The compounds used in the present invention were identified by the following mass spectrometry. A matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (MALDI-TOF MS: Ultraflex, manufactured by Bruker Daltonics, Inc.) was used. The conditions were acceleration voltage: 20 kV, mode: Reflector, and molecular weight standard: fullerene C60. The molecular weight was confirmed from the peak top value obtained.

[0051] [Synthesis Example 1] At room temperature and under a nitrogen stream, 39 parts of 3,4,9,10-perylenetetracarboxylic dianhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 30 parts of L-isoleucine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a 1000 ml three-neck flask containing 500 parts of dimethylacetamide, and the mixture was heated under reflux for 6 hours. After the reaction was completed, the vessel was cooled and concentrated under reduced pressure. Ethyl acetate was added to the residue, which was then filtered, and the filtrate was purified by silica gel column chromatography. The recovered product was further recrystallized with ethyl acetate / hexane to obtain 52 parts of an imide compound represented by the following formula (7). [ka] When this compound was measured by MALDI-TOF MS, a peak top value of 619 was obtained. At room temperature, 31 parts of the imide compound represented by formula (7) and 12 parts of 1,3-bis(4,5-dihydro-2-oxazolyl)benzene (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a 1000 ml three-neck flask containing 500 parts of toluene. The mixture was stirred for 2 hours and then at room temperature for 2 hours. After the reaction was completed, the reaction solution was concentrated using an evaporator, and then dropped into 1000 ml of methanol for reprecipitation purification. The powder was filtered under reduced pressure to obtain 40 parts of compound A101.

[0052] [Synthesis Example 2] At room temperature, 31 parts of the imide compound represented by formula (7) and 88 parts of EPOCROS (registered trademark) WS-700 (manufactured by Nippon Shokubai Co., Ltd.), which is an oxazoline group-containing polymer, were added to a 1000 ml three-neck flask containing 500 parts of toluene. The mixture was stirred for 2 hours and then at room temperature for 2 hours. After the reaction was completed, the reaction solution was concentrated using an evaporator, and then dropped into 1000 ml of methanol for reprecipitation purification. The powder was filtered under reduced pressure to obtain 50 parts of compound A201.

[0053] [Example 1] <Support> An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 260.5 mm and a diameter of 30 mm was used as a support (conductive support). Next, 50 parts of titanium oxide particles coated with oxygen-deficient tin oxide (powder resistivity: 120 Ω cm, tin oxide coverage: 40%), 40 parts of phenolic resin (Pliophen J-325, Dainippon Ink and Chemicals, Inc., resin solids content: 60%), and 55 parts of methoxypropanol were placed in a sand mill using glass beads with a diameter of 1 mm and dispersed for 3 hours to prepare a coating solution for the conductive layer. The average particle size of the titanium oxide particles coated with oxygen-deficient tin oxide in this conductive layer coating liquid was measured by centrifugal sedimentation method using a particle size distribution meter (product name: CAPA700) manufactured by Horiba, Ltd., tetrahydrofuran as a dispersion medium, and a rotation speed of 5000 rpm. As a result, the average particle size was 0.30 μm. This conductive layer coating liquid was dip-coated onto the support, and the resulting coating film was dried at 160° C. for 30 minutes to form a conductive layer having a thickness of 25 μm.

[0054] <Electron transport layer> Next, 7 parts of compound A101 was dissolved in a mixed solvent of 40 parts of methoxypropanol and 60 parts of tetrahydrofuran to prepare a coating liquid for an electron transport layer. This coating liquid for the electron transport layer was dip-coated onto the conductive layer, and the resulting coating was heated at 120° C. for 30 minutes to form an electron transport layer having a thickness of 2 μm.

[0055] <Charge generation layer> Next, a hydroxygallium phthalocyanine crystal (charge generating material) having a crystal form with peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in CuKα characteristic X-ray diffraction was prepared. 8 parts of this hydroxygallium phthalocyanine crystal, 4 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 25 parts of cyclohexanone were placed in a sand mill using glass beads with a diameter of 1 mm, and dispersed for 2 hours. Next, 250 parts of ethyl acetate were added to this to prepare a coating solution for charge generating layer. This charge generating layer coating liquid was dip coated onto the electron transport layer to form a coating film, and the resulting coating film was dried at 95° C. for 10 minutes to form a charge generating layer having a thickness of 0.25 μm.

[0056] <Hole transport layer> Next, 6 parts of an amine compound (hole transport material) represented by the following formula (8), 2 parts of an amine compound (hole transport material) represented by the following formula (9), and 10 parts of a polyester resin having a weight average molecular weight (Mw) of 100,000 and having structural units represented by the following formulas (10) and (11) in a 5 / 5 ratio, were dissolved in a mixed solvent of 40 parts of dimethoxymethane and 60 parts of chlorobenzene to prepare a coating solution for a hole transport layer. [ka] [ka] [ka] [ka] This hole transport layer coating liquid was dip-coated onto the charge generating layer, and the resulting coating was dried at 120° C. for 40 minutes to form a hole transport layer having a thickness of 22 μm.

[0057] [Image evaluation] The prepared electrophotographic photoreceptor was mounted in a modified laser beam printer (product name: LBP-2510) manufactured by Canon Inc. (primary charging: roller contact DC charging, process speed 120 mm / sec, laser exposure) in an environment of temperature 23°C and humidity 50% RH, and the output images were evaluated initially and after 10,000 images were output. Details are as follows. The process cartridge for cyan color of the above-mentioned laser beam printer was modified, and a potential probe (model 6000B-8: manufactured by Trek Japan Co., Ltd.) was attached to the development position. Next, the potential of the center part of the electrophotographic photoreceptor was measured using a surface potential meter (model 344: manufactured by Trek Japan Co., Ltd.). In addition, the light intensity of the image exposure was set so that the dark area potential (Vd) was -600V and the light area potential (Vl) was -150V. Next, the prepared electrophotographic photosensitive member was attached to a cyan process cartridge of the above-mentioned laser beam printer that had been modified so that the stress applied to the electrophotographic photosensitive member by the cleaning blade was increased, and the process cartridge was then attached to the station of the cyan process cartridge, and three solid black images were output, which were regarded as initial images. After outputting 10,000 images, three solid black images were again output, which were regarded as images after durability testing. The initial image and the image after durability were evaluated with the following criteria: A is when there were 0 to 5 white spots (white spots in the solid black image on the paper on which the image was formed) of 0.5 mm or more per solid black image, B is when there were 6 to 10 spots, and C is when there were 11 to 15 spots. The evaluation results are shown in Table 7.

[0058] [Adhesion Evaluation] A 1 mm square 100-grid grid test was conducted on the electrophotographic photoreceptor in accordance with the old JIS K5400, and the number of remaining grids out of the 100 was counted. The ratio of grids with remaining film was counted. The adhesion (%) was calculated as the number of grids that did not peel off (grids) / total number (100 grids) for the initial and endurance tests (after outputting 10,000 images). The evaluation results are shown in Table 7.

[0059] [Example 2] Except for changing the amount of hydroxygallium phthalocyanine crystals used in the charge generating layer coating liquid from 8 parts to 23 parts, an electrophotographic photoreceptor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

[0060] [Example 3] Except for adding 8.3 parts of a phenol resin (Plyophen J325) to the coating liquid for the electron transport layer, the electrophotographic photoreceptor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

[0061] [Examples 4 to 42] As shown in Table 7, except for the type of compound for the electron transport layer, the electrophotographic photoreceptor was produced and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

[0062] [Comparative Example 1] The electrophotographic photoreceptor was produced and analyzed in the same manner as in Example 1, except that the electron transport layer was prepared as described in Example 1 of U.S. Patent No. 7,371,492. The results are shown in Table 7.

[0063] [Comparative Example 2] Except for preparing the electron transport layer as described in Example 1 of JP-A-2009-505156, an electrophotographic photoreceptor was produced and analyzed in the same manner as in Example 1. The obtained results are shown in Table 7.

[0064] [Table 7]

[0065] Disclosure of an embodiment according to the present invention includes the following configuration. (Configuration 1) An electrophotographic photoreceptor having a support, an electron transport layer formed on the support, a charge generation layer formed directly on the electron transport layer, and a hole transport layer formed on the charge generation layer, wherein the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure represented by the following formula (1): [ka] (In formula (1), R 1 R represents a single bond or an unsubstituted phenylene group. 2 and R 11 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 3 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, a methoxy group, a cyano group, or a halogen atom. (Configuration 2) R in the above formula (1) 1 is a single bond or an unsubstituted phenylene group, and R 2 and R 11are each independently an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group, provided that the substituent of the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group, and the substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a halogen atom; R 3 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. (Configuration 3) The electrophotographic photoreceptor according to Structure 1 or 2, wherein the polymer having the structure represented by the formula (1) is a polymer of a composition containing a compound having an oxazoline group represented by the following formula (2) and a compound having a carboxy group represented by the following formula (3): [ka] [ka] (In formula (2), R 1 is R in the formula (1). 1 In formula (3), R 2 ~R 11 are R in the above formula (1), 2 ~R 11 is equivalent to (Configuration 4) An electrophotographic photoreceptor having a support, an electron transport layer formed on the support, a charge generation layer formed directly on the electron transport layer, and a hole transport layer formed on the charge generation layer, wherein the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure represented by the following formula (4): [ka] (In formula (4), R 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24-, where R 24 represents a single bond or an unsubstituted phenylene group, R 13 , R 22 R each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. 14 ~R 21 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom. (Configuration 5) R in the above formula (4) 12 , R 23 is a single bond or -CO-O-C2H4-NH-CO-R 24 -, where R 24 represents a single bond or an unsubstituted phenylene group, R 13 , R 22 are each independently an unsubstituted alkylene group, a substituted alkylene group, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group having 1 to 5 carbon atoms, provided that the substituent of the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group, and the substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a halogen atom; R 14 ~R 21 each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom. (Configuration 6) The electrophotographic photoreceptor according to Structure 4 or 5, wherein the polymer having the structure represented by formula (4) is a polymer of a composition containing a compound having an oxazoline group represented by formula (5) below and a compound having a carboxy group represented by formula (6) below: [ka] [ka] (In formula (5), R 12 is R in the above formula (4). 12 In formula (6), R 13 ~R 22 are R in the above formula (4), 13 ~R 22 is equivalent to (Configuration 7) 7. The electrophotographic photoreceptor according to any one of Configurations 1 to 6, wherein the content of the butyral resin in the charge generating layer is 15% by mass or more based on the total mass of the charge generating layer. (Configuration 8) The electrophotographic photoreceptor according to any one of Configurations 1 to 7, wherein the content of the polymer having the structure represented by Formula (1) or Formula (4) in the electron transport layer is 50 mass % or more based on the total mass of the electron transport layer. (Configuration 9) A process cartridge integrally supporting the electrophotographic photosensitive member according to any one of configurations 1 to 8 and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and being detachably mountable to a main body of an electrophotographic apparatus. (Configuration 10) An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of Configurations 1 to 8, an image exposure unit, a charging unit, a developing unit, and a transfer unit. [Explanation of symbols]

[0066] 1. Electrophotographic photoreceptor 2-axis 3. Charging means 4 Exposure light 5. Developing method 6 Transfer Method 7 Transfer material 8 Fixing Method 9 Cleaning Method 10 Pre-exposure light 11 Process cartridge 12 Guidance means

Claims

1. 1. An electrophotographic photoreceptor comprising a support, an electron transport layer formed on the support, a charge generation layer formed directly on the electron transport layer, and a hole transport layer formed on the charge generation layer, wherein the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure represented by the following formula (1): 【Chemistry 1】 (In formula (1), R １ R represents a single bond or an unsubstituted phenylene group. ２ and R １１ each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. R ３ ~R １０ each independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, a methoxy group, a cyano group, or a halogen atom.

2. R in the formula (1) １ is a single bond or an unsubstituted phenylene group, R ２ and R １１ are each independently an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group, provided that the substituent of the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group, and the substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a halogen atom; R ３ ~R １０ 2. The electrophotographic photoreceptor according to claim 1, wherein each of the is independently a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein the polymer having a structure represented by formula (1) is a polymer of a composition containing a compound having an oxazoline group represented by formula (2) below and a compound having a carboxy group represented by formula (3) below: 【Chemistry 2】 【Chemistry 3】 (In formula (2), R １ is R in the formula (1). １ In formula (3), R ２ ~R １１ are R in the formula (1), ２ ~R １１ (Same meaning as above.)

4. An electrophotographic photoreceptor having a support, an electron transport layer formed on the support, a charge generation layer formed directly on the electron transport layer, and a hole transport layer formed on the charge generation layer, wherein the charge generation layer contains a butyral resin, and the electron transport layer contains a polymer having a structure represented by the following formula (4): 【Chemistry 4】 (In formula (4), R １２ , R ２３ is a single bond or -CO-O-C ２ H ４ -NH-CO-R ２４ -, where R ２４ represents a single bond or an unsubstituted phenylene group, R １３ , R ２２ each independently represents an unsubstituted alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group. The substituent of the substituted alkylene group having 1 to 5 carbon atoms is at least one group selected from the group consisting of a phenyl group, a benzyl group, an imidazolylmethyl group, and a methylthioethyl group. The substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, a halogen atom, a methoxy group, and a nitro group. R １４ ~R ２１ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, or a halogen atom.

5. R in the formula (4) １２ , R ２３ is a single bond or -CO-O-C ２ H ４ -NH-CO-R ２４ -, where R ２４ represents a single bond or an unsubstituted phenylene group, R １３ , R ２２ are each independently an unsubstituted alkylene group, a substituted alkylene group, an unsubstituted phenylene group, a substituted phenylene group, or a benzylene group having 1 to 5 carbon atoms, provided that the substituent of the substituted alkylene group having 1 to 5 carbon atoms is a methylthioethyl group, and the substituent of the substituted phenylene group is at least one group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a halogen atom; R １４ ~R ２１ 5. The electrophotographic photoreceptor according to claim 4, wherein each of independently represents a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or a halogen atom.

6. The electrophotographic photoreceptor according to claim 4 or 5, wherein the polymer having a structure represented by formula (4) is a polymer of a composition containing a compound having an oxazoline group represented by formula (5) below and a compound having a carboxy group represented by formula (6) below: 【Chemistry 5】 【Chemistry 6】 (In formula (5), R １２ is R in the formula (4). １２ In formula (6), R １３ ~R ２２ are R in the formula (4), １３ ~R ２２ (Same meaning as above.)

7. 6. The electrophotographic photoreceptor according to claim 1, wherein the content of the butyral resin in the charge generating layer is 15% by mass or more based on the total mass of the charge generating layer.

8. 6. The electrophotographic photoreceptor according to claim 1, wherein the content of the polymer having the structure represented by Formula (1) or Formula (4) in the electron transport layer is 50 mass % or more with respect to the total mass of the electron transport layer.

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

10. 6. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1, 2, 4 or 5, an image exposure unit, a charging unit, a developing unit and a transfer unit.

Images