Electrophotographic photoreceptor, process cartridge, and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor that can reduce residual potential, and can reduce bright part potential fluctuation in short-term use in a more advanced way.SOLUTION: An electrophotographic photoreceptor has a support, an undercoat layer, formed immediately above the support, and a photosensitive layer formed on the undercoat layer. When the ionization potential of the undercoat layer is defined as IPu, the IPu is 6.0 eV or more. When the ionization potential of the support is defined as IPs, the IPs is less than the IPu. The undercoat layer contains a compound (α). When the ionization potential of the compound (α) is defined as IPα, the IPα is 5.0 eV or more and 5.4 eV or less. The IPs and the IPα satisfy the following relational expression (1). (1) IPs≥IPα-1.0.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, there has been a demand for higher image quality and greater stability in images outputted from electrophotographic apparatuses. Techniques for solving such problems are disclosed in Patent Documents 1, 2 and 3. Patent Document 1 describes an electrophotographic photoreceptor that contains a specific perinone compound and an amine compound having an ionization potential in the atmosphere of 5.4 eV or more and 5.9 eV or less. Patent Document 2 describes an electrophotographic photoreceptor having an undercoat layer containing a specific perinone compound and polyurethane. Patent Document 3 describes an electrophotographic photoreceptor in which an undercoat layer contains a triarylamine compound having a reactive group, a curing agent, and an electron transporting material, and also contains a butyral resin in a specific ratio. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-101652 A [Patent Document 2] JP 2020-46640 A [Patent Document 3] JP 2023-115641 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the studies of the present inventors, it has been found that the electrophotographic photoreceptors described in Patent Documents 1, 2, and 3 have a high residual potential and there is room for improvement in terms of fluctuation in the bright area potential. Also, it has been found that in some of the electrophotographic photoreceptors described in Patent Document 3, although the residual potential is relatively small, the fluctuation in the bright area potential can be relatively large. An object of the present invention is to provide an electrophotographic photoreceptor which has a low residual potential and small fluctuation in the bright area potential. [Means for solving the problem]

[0005] The present invention provides an electrophotographic photoreceptor having a support, an undercoat layer formed directly on the support, and a photosensitive layer formed on the undercoat layer, When the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more; When the ionization potential of the support is IPs, the IPs is less than the IPu, the undercoat layer contains a compound (α), When the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα satisfy the following relational formula (1): IPs≧IPα-1.0 (1) The electrophotographic photoreceptor is characterized in that Effect of the Invention

[0006] According to the present invention, it is possible to provide an electrophotographic photoreceptor having a low residual potential and small fluctuation in bright area potential. [Brief description of the drawings]

[0007] [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

[0008] As a result of investigations conducted by the present inventors, it was found that in the techniques described in Patent Documents 1, 2, and 3, injection of holes from the support to the undercoat layer is small, and electrons that remain in the undercoat layer are difficult to cancel, resulting in a high residual potential and large fluctuations in the bright area potential. It has also been found that some of the photoconductors described in Patent Document 3 have relatively low residual potentials, but the fluctuations in the bright area potential can be large. In order to solve this technical problem, the present inventors have conducted a study on the injection of holes from the support to the undercoat layer. As a result of the above-mentioned investigation, it has been found that the above-mentioned technical problems can be solved by providing an electrophotographic photoreceptor having the following configuration.

[0009] That is, the present invention provides an electrophotographic photoreceptor having a support, an undercoat layer formed directly on the support, and a photosensitive layer formed on the undercoat layer, When the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more; When the ionization potential of the support is IPs, the IPs is less than the IPu, the undercoat layer contains a compound (α), When the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα satisfy the following relational formula (1): IPs≧IPα-1.0 (1) The electrophotographic photoreceptor is characterized in that

[0010] The present inventors speculate as follows about the mechanism by which the above-mentioned configuration of the present invention can solve the above technical problems. The undercoat layer formed directly on the support contains an electron transporting compound and has a large ionization potential, and due to its characteristics, injection of holes from the support to the undercoat layer is small, and removal of electrons in the undercoat layer is mainly due to the transport of electrons. Therefore, if electrons remain in the undercoat layer, they are difficult to remove from the undercoat layer, and the residual potential is likely to increase. It is presumed that in the prior art, the residual potential increased because the electrons remaining in the undercoat layer were difficult to remove, resulting in large fluctuations in the bright area potential. Moreover, if the ionization potential of the compound contained in the undercoat layer is too small, the residual potential can be reduced, but the balance with the dark area potential is lost, resulting in large fluctuations in the bright area potential.

[0011] In the present invention, when the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more, when the ionization potential of the support is IPs, the IPs is less than the IPu, when the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα are IPs≧IPα-1.0 (1) It is believed that satisfying the above requirement promotes proper injection of holes from the support to the undercoat layer, facilitates removal of electrons that tend to remain in the undercoat layer, reduces the residual potential, and further suppresses fluctuations in the bright area potential.

[0012] <About ionization potential measurement> Ionization potential is usually derived by atmospheric photoelectron yield spectroscopy (PYSA) or photoelectron yield spectroscopy (PYS). It is known that the values ​​derived by the above two methods differ depending on the amount of moisture on the sample surface. In the present invention, the ionization potential is derived by photoelectron yield spectroscopy (PYS). The measurement is performed in a nitrogen atmosphere, and the horizontal axis represents the energy of the irradiated ultraviolet light, the vertical axis represents the square root of the amount of photoelectron emission, and the ionization potential can be determined from the intersection point between the slope and the background.

[0013] [Electrophotographic photoreceptor] The electrophotographic photoreceptor of the present invention has a support, an undercoat layer formed directly on the support, and a photosensitive layer formed on the undercoat layer. The support is preferably cylindrical. The photosensitive layer preferably comprises a charge generating layer formed on the undercoat layer and a hole transport layer formed on the charge generating layer. The method for producing the electrophotographic photoreceptor of the present invention includes a method of preparing a coating solution for each layer described later, forming a coating film of the coating solution, and drying and / or curing the coating film. In this case, the coating method for the coating solution (the method for forming the coating film) includes blade coating, curtain coating, wire bar coating, ring coating, etc. Among these, dip coating is preferable from the viewpoint of efficiency and productivity. The support and each layer will be described below.

[0014] <Support> The support is preferably a cylindrical support. The surface of the support is preferably formed of Al and / or an Al alloy. The surface of the support may be subjected to a hot water treatment, a blasting treatment, a cutting treatment, or the like. In order to more efficiently obtain the effects of the present invention, the ionization potential IPs of the support surface is preferably 5.6 eV or more and 5.8 eV or less.

[0015] <Undercoat layer> The undercoat layer of the electrophotographic photoreceptor of the present invention is When the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more; When the ionization potential of the support is IPs, the IPs is less than the IPu, the undercoat layer contains a compound (α), When the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα satisfy the following relational formula (1). IPs≧IPα-1.0 (1) In the present invention, the ionization potential IPu of the undercoat layer is preferably 6.0 eV or more and 6.3 eV or less. In the present invention, from the viewpoint of efficiently injecting holes from the support to the undercoat layer, it is preferable that the IPs and the IPα satisfy the following relational formula (2). IPs≧IPα(2) For the same reason, in the present invention, it is more preferable that the IPs and the IPα satisfy the following relational formula (3). IPs-IPα ≥ 0.3 (3)

[0016] The compound (α) contained in the undercoat layer according to the present invention has the IPα of 5.0 eV or more and 5.4 eV or less. The compound (α) contained in the undercoat layer according to the present invention is preferably a compound represented by the following formula (α). [ka] (In the formula (α), Ar 1 and Ar 2 each independently represents a substituted or unsubstituted phenyl group. The substituent is an alkyl group or an alkoxy group. 3 represents an n-valent aromatic group, where n is an integer of 1 to 3.

[0017] The compound (α) represented by the formula (α) may be used alone or in combination of two or more kinds.

[0018] (Regarding compound (α) represented by formula (α)) The compound (α) represented by the formula (α) is a hole transporting material. Specific examples of the compound (α) represented by the formula (α) and the ionization potential IPα of the compound (α) are shown in Table 1-1 below.

[0019] [Table 1-1]

[0020] In the present invention, the ionization potential is measured using a photoelectron spectrometer AC-3 manufactured by Riken Keiki Co., Ltd. under a nitrogen atmosphere.

[0021] The undercoat layer in the present invention preferably contains a cured product of a composition containing a compound represented by the following formula (B1) or (B2). [ka] [ka] (In formulas (B1) and (B2), R 101 ~R 106 and R 201 ~R 210 each independently represents a monovalent group represented by the following formula (C), a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. 101 ~R 106 At least one of, and R 201 ~R 210 At least one of the above is a monovalent group represented by the following formula (C). One of the CH2 of the alkyl group may be substituted with O or S, or one of the CH of the alkyl group may be substituted with N. The substituent of the substituted alkyl group is at least one group selected from the group consisting of an aryl group, an alkoxycarbonyl group, a halogen atom, and a hydroxy group. The substituent of the substituted aryl group and the substituted heterocyclic group is at least one group selected from the group consisting of a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, and an alkoxy group. [ka] (In formula (C), at least one of a, b, and c has at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group. l and m each independently represent 0 or 1, and the sum of l and m is 0 or more and 2 or less. a represents an alkylene group having 1 to 6 carbon atoms in the main chain, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a benzyl group, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a phenyl group, and these alkylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. One of the CH2 in the main chain of these alkylene groups may be substituted with O or S, or one of the CH in the main chain of these alkylene groups may be substituted with N. b represents a phenylene group, an alkyl group-substituted phenylene group having from 1 to 6 carbon atoms, a nitro group-substituted phenylene group, a halogen group-substituted phenylene group, or an alkoxy group-substituted phenylene group, and these phenylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. c represents a hydrogen atom, a carboxy group, an alkyl group having 1 to 6 carbon atoms in its main chain, or an alkyl group having 1 to 6 carbon atoms in its main chain substituted with an alkyl group having 1 to 5 carbon atoms, and these alkyl groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent.

[0022] The compound selected from the group consisting of the compound represented by formula (B1) and the compound represented by formula (B2) may be used alone or in combination of two or more kinds.

[0023] (Regarding the compound represented by formula (B1) and the compound represented by formula (B2)) The compound represented by formula (B1) and the compound represented by formula (B2) are electron transporting materials. The compound represented by formula (B1) and the compound represented by formula (B2) are shown in the following Tables 2-1 to 2-7. Compounds (B101) to (B168) are specific examples of the compound represented by formula (B1), and compounds (B201) to (B231) are specific examples of the compound represented by formula (B2). In Table 2, when "(H)" is written for c, it means that c is a hydrogen atom in the structure shown in the a or b column, and the structure of formula (B) is the structure shown in the a or b column. When the a or b column is (-), it means that l or m is 0.

[0024] The following are specific examples, and the effects of the present invention are not achieved by only the following specific examples. These compounds may be used alone or in combination.

[0025] [Table 2-1]

[0026] [Table 2-2]

[0027] [Table 2-3]

[0028] [Table 2-4]

[0029] [Table 2-5]

[0030] [Table 2-6]

[0031] [Table 2-7]

[0032] The structure of the monovalent group represented by formula (C) in the above table can be said to be as follows. That is, the monovalent group represented by formula (C) is an alkyl group having 1 to 12 carbon atoms, which may have a substituent, a phenyl group, or a phenylalkyl group having 6 to 12 carbon atoms, provided that the substituent that the alkyl group having 1 to 12 carbon atoms may have is any one of a hydroxy group, a thiol group, an amino group, a carboxy group, an alkoxycarbonyl group, and an alkoxy group; The substituent that the phenyl group or the phenylalkyl group having 6 to 12 carbon atoms may have is a methyl group, an ethyl group, a hydroxymethyl group, a hydroxyethyl group, a carboxymethyl group, a carboxyethyl group, a hydroxy group, a thiol group, an amino group, a carboxy group, or an alkoxycarbonyl group. In the alkyl group having 1 to 12 carbon atoms or the alkyl group in the phenylalkyl group having 6 to 12 carbon atoms, one CH2 may be substituted with O or S, or one CH may be substituted with N, However, the monovalent group represented by formula (C) contains any one of a hydroxy group, a thiol group, an amino group, or a carboxy group.

[0033] In order to obtain the effects of the present invention more efficiently, the mass ratio of the content of the compound (α) in the composition to the content of the compound represented by the formula (B1) or (B2) in the composition is preferably 0.035 to 0.150, i.e., the content of the compound (α) is preferably 3.5 to 15% by mass relative to the compound represented by the formula (B1) or (B2).

[0034] The undercoat layer may contain, as a resin, a polyester resin, a polycarbonate resin, a polyvinyl acetal resin, an acrylic resin, an epoxy resin, a melamine resin, a polyurethane resin, a phenol resin, a polyvinyl phenol resin, an alkyd resin, a polyvinyl alcohol resin, a polyethylene oxide resin, a polypropylene oxide resin, a polyamide resin, a polyamic acid resin, a polyimide resin, a polyamideimide resin, a cellulose resin, or the like.

[0035] The undercoat layer may contain metal oxide particles, metal particles, conductive polymers, etc. for the purpose of improving electrical properties. 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 an additive. In order to more efficiently obtain the effects of the present invention, the thickness of the undercoat layer is preferably 0.5 μm or more and 2.4 μm or less. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film of the coating solution for the undercoat layer, and drying and / or curing the coating film. Examples of the solvent used in the coating solution for the undercoat layer include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0036] <Photosensitive layer> The photosensitive layer of an electrophotographic photoreceptor is mainly classified into (1) a laminated type photosensitive layer and (2) a single-layer type photosensitive layer. (1) The laminated type photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer (hole transport layer) containing a charge transport material. (2) The single-layer type photosensitive layer is a photosensitive layer that contains both a charge generation material and a charge transport material.

[0037] (1) Laminated photosensitive layer The laminated type photosensitive layer has a charge generating layer and a charge transport layer.

[0038] (1-1) Charge generation layer The charge generating layer preferably contains a charge generating substance and a resin (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, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. The content of the charge generating material in the charge generating layer is preferably from 40% by mass to 85% by mass, and more preferably from 60% by mass to 80% by mass, based on the total mass of the charge generating layer. Examples of the 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, polyvinyl chloride resin, etc. Among these, polyvinyl butyral resin is preferable. The charge generating layer may also contain additives such as antioxidants and ultraviolet absorbing agents, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds. The thickness of the charge generating layer is preferably from 0.1 μm to 1 μm, and more preferably from 0.15 μm to 0.4 μm. The charge generating layer can be formed by preparing a coating liquid for the charge generating layer containing the above-mentioned materials and solvent, forming a coating film of the coating liquid for the charge generating layer, and drying the coating film. Examples of the solvent used in the coating liquid for the charge generating layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0039] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a resin (binder resin). Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably from 25% by weight to 70% by weight, and more preferably from 30% by weight to 55% by weight, based on the total weight of the charge transport layer. 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 of the charge transport material to the resin in the charge transport layer (mass ratio, charge transport material:resin) is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0040] The charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles. The thickness of the charge 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. The charge transport layer can be formed by preparing a coating liquid for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film of the coating liquid for the charge transport layer, and drying the coating film. Examples of the solvent used in the coating liquid for the charge transport layer include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0041] <Protective layer> In the present invention, a protective layer may be provided on the photosensitive layer. By providing the protective layer, durability can be improved. The protective layer preferably contains conductive particles and / or a charge transport material and a resin. The conductive particles include metal oxide particles, metal particles, etc. The metal oxides include titanium oxide, zinc oxide, tin oxide, indium oxide, etc. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred. Examples of the resin include polyester resin, acrylic resin, phenoxy resin, polycarbonate resin, polystyrene resin, phenol resin, melamine resin, epoxy resin, etc. Among these, polycarbonate resin, polyester resin, and acrylic resin are preferable.

[0042] 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 polymerization 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 compound having a charge transport function may be used as the monomer having a polymerizable functional group.

[0043] The protective layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles. The 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 of the coating solution for the protective layer, and drying and / or curing the coating film. Examples of the solvent used in the coating solution for the protective layer include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0044] [Process cartridges, electrophotographic devices] The process cartridge of the present invention is characterized in that it integrally supports the above-mentioned 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 electrophotographic apparatus of the present invention is characterized by comprising the above-mentioned electrophotographic photoreceptor, as well as a charging means, an exposing means, a developing means and a transferring means.

[0045] FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member. A cylindrical electrophotographic photoreceptor 1 is rotated at a predetermined peripheral speed in the direction of the arrow around an axis 2. The surface of the electrophotographic photoreceptor 1 is charged by charging means 3 to a predetermined positive or negative potential. In FIG. 1, a roller charging method using a roller-type charging member (charging roller) is shown, but other charging methods such as a corona charging method, a proximity charging method, and an injection charging method may also be used. 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 development 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 resulting image is printed out to the outside of the electrophotographic device. The electrophotographic apparatus may have a cleaning unit 9 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. Alternatively, a so-called cleanerless system may be used in which the deposits are removed by the developing unit 5 or the like without providing a separate cleaning unit 9. The electrophotographic apparatus may have a charge eliminating mechanism that eliminates charge on the surface of the electrophotographic photosensitive member 1 with pre-exposure light 10 from a pre-exposure means (not shown). In addition, a guide means 12 such as a rail may be provided in order to mount and remove the process cartridge 11 of the present invention to and from the main body of the electrophotographic apparatus.

[0046] The electrophotographic photoreceptor of the present invention can be used in laser beam printers, LED printers, copiers, facsimiles, and combination machines thereof. EXAMPLES

[0047] 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 based on mass unless otherwise specified.

[0048] [Production Examples of Compounds Represented by Formula (B1) and (B2)] The compound represented by formula (B1) (derivative of an electron transport material) can be synthesized by using a known synthesis method described in, for example, U.S. Pat. No. 4,442,193, U.S. Pat. No. 4,992,349, U.S. Pat. No. 5,468,583, and Chemistry of Materials, Vol. 19, No. 11, 2703-2705 (2007). It can also be synthesized by reacting naphthalenetetracarboxylic dianhydride, which is available from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd., and Johnson Matthey Japan Inc., with a monoamine derivative.

[0049] The compound represented by formula (B1) has a polymerizable functional group (hydroxy group, thiol group, amino group, carboxy group) capable of polymerizing with the isocyanate group of the isocyanate compound. Methods for introducing these substituents into the compound represented by formula (B1) include a method for directly introducing a polymerizable functional group into the compound represented by formula (B1) and a method for introducing a structure having the above-mentioned polymerizable functional group or a functional group that can be a precursor of the polymerizable functional group. Examples of the methods described below include a method for introducing a functional group-containing aryl group by using a cross-coupling reaction using a palladium catalyst and a base based on a halide of a naphthylimide derivative. Another example includes a method for introducing a functional group-containing alkyl group by using a cross-coupling reaction using an FeCl3 catalyst and a base based on a halide of a naphthylimide derivative. Another example includes a method for introducing a hydroxyalkyl group or a carboxy group by using an epoxy compound or CO2 after lithiation based on a halide of a naphthylimide derivative. There is a method of using, as a raw material for synthesizing a naphthylimide derivative, a naphthalenetetracarboxylic dianhydride derivative or a monoamine derivative having the above-mentioned polymerizable functional group or a functional group that can be a precursor of the polymerizable functional group.

[0050] The compound represented by formula (B2) (derivative of an electron transport material) can be synthesized by using a known synthesis method described in, for example, Journal of the American Chemical Society, Vol. 129, No. 49, 15259-15278 (2007). Alternatively, it can be synthesized by reacting perylene tetracarboxylic dianhydride, which can be purchased as a reagent from Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan K.K., or Johnson Matthey Japan Inc., with a monoamine derivative.

[0051] The compound represented by formula (B2) has a functional group (hydroxy group, thiol group, amino group, carboxy group) that can polymerize with the isocyanate group of the isocyanate compound. As a method for introducing these polymerizable functional groups into the compound represented by formula (B2), there is a method for directly introducing a polymerizable functional group into the compound represented by formula (B2), as well as a method for introducing a structure having the above-mentioned polymerizable functional group or a functional group that can be a precursor of the polymerizable functional group. As the method described later, for example, a method using a cross-coupling reaction using a palladium catalyst and a base based on a halide of a perylene imide derivative is exemplified. In addition, there is a method using a cross-coupling reaction using an FeCl3 catalyst and a base based on a halide of a perylene imide derivative. In addition, there is a method for using a perylene tetracarboxylic dianhydride derivative or a monoamine derivative having the above-mentioned polymerizable functional group or a functional group that can be a precursor of the polymerizable functional group as a raw material for synthesizing the perylene imide derivative.

[0052] (Synthesis Example 1) To 200 parts of dimethylacetamide, 5.4 parts of naphthalenetetracarboxylic dianhydride, 4 parts of 2-methyl-6-ethylaniline, and 3 parts of 2-amino-1-butanol were added under a nitrogen atmosphere, and the mixture was stirred at room temperature for 1 hour to prepare a solution. After preparing the solution, the mixture was refluxed for 8 hours, and the precipitate was filtered off and recrystallized with ethyl acetate to obtain 1.0 part of compound B101.

[0053] (Synthesis Example 2) To 200 parts of dimethylacetamide, 5.4 parts of naphthalenetetracarboxylic dianhydride, 4 parts of 4-heptylamine, and 3 parts of 2-amino-1,3-propanediol were added under a nitrogen atmosphere, and the mixture was stirred at room temperature for 1 hour to prepare a solution. After preparing the solution, the mixture was refluxed for 8 hours, and separated by silica gel column chromatography (eluent: ethyl acetate / toluene), and the fraction containing the target substance was concentrated. The concentrate was recrystallized with a mixed solution of ethyl acetate / toluene to obtain 2.0 parts of compound B154.

[0054] (Synthesis Example 3) To 200 parts of dimethylacetamide, 7.4 parts of perylenetetracarboxylic dianhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), 4 parts of 2,6-diethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4 parts of 2-aminophenylethanol were added under a nitrogen atmosphere and stirred at room temperature for 1 hour to prepare a solution. After preparing the solution, the mixture was refluxed for 8 hours, and the precipitate was filtered off and recrystallized with ethyl acetate to obtain 5.0 parts of compound B203.

[0055] <Manufacture of support> (Example of manufacturing support 1) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 370 mm and a diameter of 30.5 mm, whose surface had been roughened by cutting at a pitch of 0.4 mm using a bit with a radius of 40 mm, was ultrasonically cleaned in an alkaline solution of pH=11, the alkaline solution was removed with pure water, and the cylinder was left to stand in hot water at 95°C for 90 seconds and then dried at room temperature to obtain Support 1.

[0056] (Example of manufacturing support 2) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 370 mm and a diameter of 30.5 mm, whose surface had been roughened by cutting at a pitch of 0.4 mm using a bit with a radius of 40 mm, was ultrasonically cleaned in an alkaline solution of pH=11, the alkaline solution was removed with pure water, and the cylinder was left to stand in hot water at 95°C for 60 seconds and then dried at room temperature to obtain support 2.

[0057] (Example of manufacturing support 3) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 370 mm and a diameter of 30.5 mm, whose surface had been roughened by cutting at a pitch of 0.4 mm using a bit with a radius of 40 mm, was ultrasonically cleaned in an alkaline solution of pH=11, the alkaline solution was removed with pure water, and the cylinder was left to stand in hot water at 95°C for 100 seconds and then dried at room temperature to obtain support 3.

[0058] (Production example of support 4) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 370 mm and a diameter of 30.5 mm, whose surface had been roughened by cutting at a pitch of 0.4 mm using a bit with a radius of 40 mm, was ultrasonically cleaned in an alkaline solution of pH=11, the alkaline solution was removed with pure water, and the cylinder was left to stand in warm water at 60°C for 15 seconds and then dried at room temperature to obtain Support 4.

[0059] <Manufacture of electrophotographic photoreceptor> (Example of manufacturing photoreceptor 1) Support 1 was used as the support. Next, 3.11 parts of compound (B154) as an electron transport material, 0.40 parts of styrene-acrylic resin (trade name: UC-3920, manufactured by Toagosei) as a resin, 0.4 parts of polyvinyl butyral resin (trade name: BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 6.49 parts of blocked isocyanate compound (trade name: SBB-70P, manufactured by Asahi Kasei Co., Ltd.) as an isocyanate compound were dissolved in a mixed solvent of 48 parts of 1-butanol and 24 parts of acetone. 0.25 parts of compound (α1) (manufactured by Tokyo Kasei Kogyo Co., Ltd.) in 6 parts of tetrahydrofuran were added to this solution and stirred for 1 hour. Then, pressure filtration was performed using a Teflon (registered trademark) filter (product name: PF020) manufactured by ADVANTEC. The obtained coating liquid for undercoat layer was dip-coated onto the above-mentioned support, and the obtained coating film was heated at 170° C. for 40 minutes to be cured (polymerized), thereby forming an undercoat layer with a thickness of 1.8 μm on the support.

[0060] Next, 20 parts of hydroxygallium phthalocyanine crystal (charge generating substance) having peaks at Bragg angles 2θ±0.2° of 7.4° and 28.2° in CuKα characteristic X-ray diffraction, 0.2 parts of a calixarene compound represented by the following formula (P), [ka] 10 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 600 parts of cyclohexanone were placed in a sand mill using glass beads with a diameter of 1 mm and dispersed for 4 hours. Then, 700 parts of ethyl acetate were added to prepare a coating liquid for a charge generating layer. This coating liquid for a charge generating layer was dip-coated on the undercoat layer, and the resulting coating was dried at 80°C for 15 minutes to form a charge generating layer with a thickness of 0.17 μm.

[0061] Next, 30 parts of a compound represented by the following formula (Q) (charge transport material), 60 parts of a compound represented by the following formula (R) (charge transport material), and 10 parts of a compound represented by the following formula (S) (charge transport material), [ka] [ka] [ka] And 100 parts of polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation, bisphenol Z type polycarbonate) and 0.02 parts of polycarbonate resin (viscosity average molecular weight Mv: 20000) represented by the following formula (T): [ka] (In formula (T), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two units.) The above was dissolved in a mixed solvent of 600 parts of mixed xylene and 200 parts of dimethoxymethane to prepare a coating solution for a charge transport layer. The coating solution for a charge transport layer was dip-coated onto the charge generating layer to form a coating film, and the resulting coating film was dried at 100° C. for 30 minutes to form a charge transport layer with a thickness of 18 μm.

[0062] Next, a mixed solvent of 20 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeorola H, manufactured by Zeon Corporation) and 20 parts of 1-propanol was filtered through a Polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.). 90 parts of a hole transporting compound represented by the following formula (U): [ka] 70 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane and 70 parts of 1-propanol were added to the mixed solvent. The mixture was filtered with a polyflon filter (product name: PF-020, manufactured by Advantec Toyo) to prepare a coating solution for a second charge transport layer (protective layer). The coating solution for the second charge transport layer was dip-coated on the charge transport layer, and the resulting coating film was dried at 50°C for 6 minutes in air. Thereafter, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an acceleration voltage of 70 kV and an absorbed dose of 8000 Gy while rotating the support (irradiated body) at 200 rpm in nitrogen. Subsequently, the temperature was raised from 25°C to 125°C in nitrogen over 30 seconds to heat the coating film. The oxygen concentration in the atmosphere during the electron beam irradiation and subsequent heating was 15 ppm. Next, a heat treatment was carried out in the atmosphere at 100° C. for 30 minutes to form a second charge transport layer (protective layer) having a thickness of 5 μm that was cured by electron beam.

[0063] Next, linear grooves were formed on the surface of the protective layer using an abrasive sheet (product name: GC3000, manufactured by Riken Corundum). The feed speed of the abrasive sheet was 40 mm / min, the rotation speed of the workpiece was 240 rpm, and the abrasive sheet pressing pressure against the workpiece was 7.5 N / m. 2 The feed direction of the abrasive sheet and the rotation direction of the workpiece were the same. A backup roller with an outer diameter of 40 cm and an Asker C hardness of 40 was used. Under these conditions, linear grooves were formed on the peripheral surface of the workpiece for 10 seconds. In this manner, the photoreceptor 1 was produced.

[0064] (Production examples of photoreceptors 2 to 76) Except for changing the support, the compound represented by formula (α), the amount added, and the film thickness of the undercoat layer shown in Tables 3-1-1 and 3-1-2 as shown in Tables 3-1-1 and 3-1-2, electrophotographic photoreceptors were produced in the same manner as in the production example of photoreceptor 1. The obtained electrophotographic photoreceptors are designated photoreceptors 2 to 76.

[0065] [Table 3-1]

[0066] [Table 3-2]

[0067] [Table 3-3]

[0068] [Table 3-4]

[0069] (Example of manufacturing photoreceptor 101) A cylindrical aluminum substrate having a length of 370 mm and a diameter of 30.5 mm was used as the support. An electrophotographic photoreceptor was produced in the same manner as in the production example of photoreceptor 1, except that the compound (α1) was not added to the support and the coating liquid for undercoat layer as shown in Table 4. The obtained electrophotographic photoreceptor is designated as photoreceptor 101.

[0070] (Example of manufacturing the photoreceptor 102) An aluminum cylinder (JIS-A3003, aluminum alloy) with a length of 370 mm and a diameter of 30.5 mm was used as a support (conductive support). Next, 19.5 parts of blocked isocyanate (Sumidur BL3175, manufactured by Sumika Bayer Urethane Co., Ltd., solid content 75% by mass) and 7.5 parts of butyral resin (S-LEC BL-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 130 parts of methyl ethyl ketone. Next, 34 parts of Pigment Orange 43 (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.9 parts of Comparative Example Compound 1 were mixed with the above-mentioned solution, and then dispersed with a sand mill for 10 hours to obtain a dispersion. 0.005 parts of bismuth carboxylate (K-KATXK-640, manufactured by King Industry Co., Ltd.) were added to this dispersion to obtain a coating solution for an undercoat layer. This coating solution for an undercoat layer was applied by immersion onto the support and cured at 160°C for 60 minutes to form an undercoat layer with a thickness of 7 μm. An electrophotographic photoreceptor was produced in the same manner as in the production example of photoreceptor 1, in which all layers above the undercoat layer were formed. The obtained electrophotographic photoreceptor is designated as photoreceptor 102.

[0071] (Example of manufacturing photoreceptors 103-104) Except for the formation of the undercoat layer being changed as shown in Tables 4-1 and 4-2, electrophotographic photoreceptors were produced in the same manner as for the photoreceptor 102. The obtained photoreceptors are designated as photoreceptors 103-104.

[0072] (Example of manufacturing photoreceptor 105) An electrophotographic photoreceptor was produced in the same manner as in Photoreceptor 1, except that a support described in Tables 4-1 and 4-2 was used and the formation of the undercoat layer was changed as described in Tables 4-1 and 4-2. The obtained photoreceptor is designated as Photoreceptor 105.

[0073] (Example of manufacturing the photoreceptor 106) First, 46.7 parts of blocked isocyanate (Sumidur BL3175, manufactured by Sumika Bayer Urethane Co., Ltd., solid content 75% by mass) as a curing agent and 5 parts of a triarylamine compound having a reactive group (comparative example compound 10) were dissolved in 100 parts of methyl ethyl ketone and 100 parts of cyclopentanone. 60 parts of Pigment Orange 43 (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed with this solution and dispersed in a sand mill using glass beads for 4 hours, and 0.001 parts of bismuth carboxylate (manufactured by King Industry Co., Ltd.) was added as a catalyst to the obtained dispersion to obtain a coating liquid for an undercoat layer. This coating liquid was dip-coated on a cylindrical aluminum support shown in Table 4-1, and dried and cured at 160°C for 45 minutes to form an undercoat layer with a thickness of 4.2 μm. All layers above the undercoat layer were manufactured in the same manner as in the manufacturing example of photoreceptor 1 to produce an electrophotographic photoreceptor. The obtained electrophotographic photoreceptor is called photoreceptor 106.

[0074] (Example of manufacturing photoreceptor 107) First, 40 parts of blocked isocyanate (Sumidur BL3175, manufactured by Sumika Bayer Urethane Co., Ltd., solid content 75% by mass) as a curing agent, 5 parts of a triarylamine compound having a reactive group (comparative example compound 15), and 5 parts of a butyral resin (S-LEC BL-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 100 parts of methyl ethyl ketone and 100 parts of cyclopentanone. 60 parts of Pigment Orange 43 (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed with this solution and dispersed in a sand mill using glass beads for 4 hours, and 0.001 parts of bismuth carboxylate (manufactured by King Industry Co., Ltd.) was added as a catalyst to the obtained dispersion to obtain a coating liquid for an undercoat layer. This coating liquid was applied by immersion onto a cylindrical aluminum support shown in Table 4, and dried and cured at 160 ° C. for 45 minutes to form an undercoat layer with a thickness of 4.2 μm. An electrophotographic photoreceptor was produced in the same manner as in the production example of photoreceptor 1, in which all layers above the undercoat layer were formed. The obtained electrophotographic photoreceptor is designated as photoreceptor 107.

[0075] (Example of manufacturing the photoreceptor 108) First, 40 parts of blocked isocyanate (Sumidur BL3175, manufactured by Sumika Bayer Urethane Co., Ltd., solid content 75% by mass) as a curing agent, 5 parts of a triarylamine compound having a reactive group (comparative example compound 15), and 5 parts of a butyral resin (S-LEC BL-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 100 parts of methyl ethyl ketone and 100 parts of cyclopentanone. 60 parts of Pigment Orange 43 (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed with this solution and dispersed in a sand mill using glass beads for 4 hours, and 0.001 parts of bismuth carboxylate (manufactured by King Industry Co., Ltd.) was added as a catalyst to the obtained dispersion to obtain a coating liquid for an undercoat layer. This coating liquid was applied by immersion onto a cylindrical aluminum support shown in Table 4, and dried and cured at 160 ° C. for 45 minutes to form an undercoat layer with a thickness of 1.8 μm. An electrophotographic photoreceptor was produced in the same manner as in the production example of photoreceptor 1, in which all layers above the undercoat layer were formed. The obtained electrophotographic photoreceptor is designated as photoreceptor 108.

[0076] [Table 4-1]

[0077] [Table 4-2]

[0078] [Table 5-1]

[0079] [Table 5-2]

[0080] [evaluation] (Examples 1 to 76 and Comparative Examples 1 to 8) Photoreceptor 1 was prepared and attached to the cyan station of an electrophotographic apparatus (copying machine) (product name: imagePRESSC910, manufactured by Canon Inc.) which was an evaluation apparatus, and evaluation was carried out as follows.

[0081] The surface potential of the electrophotographic photosensitive member was measured by removing the developing cartridge from the evaluation device, setting a potential probe (product name: model 6000B-8, manufactured by Trek Corporation) thereon, and using a surface potential meter (model 344, manufactured by Trek Corporation). The dark potential (Vd) and the light potential (Vl) were measured at 12 points at 30° intervals in the circumferential direction at the axial center position of the electrophotographic photosensitive member, and the average value for one revolution was calculated as each value. First, in a 30° C. / 80% RH environment, the voltage applied to the charging roller was adjusted so that the dark area potential (Vd) of the first A4 sheet of the electrophotographic photoreceptor used for evaluation was −680 V. Next, the image exposure light amount was adjusted so that the light area potential (Vl) of the first A4 sheet of paper was −380 V. After 3 hours, in an environment of 30°C / 80% RH, 200 sheets were passed through the test piece with the voltage applied to the charging roller set so that the dark potential (Vd) was -680 V and the amount of exposure light set so that the bright potential (Vl) was -380 V, and the bright potential (Vl) was measured during this period. The bright area potentials of the first and 200th sheets were calculated using the above method, and the absolute value of (initial bright area potential - bright area potential after 200 sheets were passed) was calculated and this value was calculated as the short-term potential fluctuation value. The evaluation results are shown in Tables 3-1-1, 3-1-2, 3-2-1, 3-2-2, 4-1-1, and 4-1-2.

[0082] The measurement of the residual potential was started when the electrophotographic photoconductor made one revolution from the position where the charging was lost after the measurement of the light area potential after 200 sheets were passed, and the measurement was then performed for one revolution of the electrophotographic photoconductor. The measurement of the residual potential was also performed at 12 points every 30° in the circumferential direction, similar to the measurement of the light area potential. The average value during one revolution of the electrophotographic photoconductor was then calculated, and this was taken as the residual potential. The evaluation results obtained are shown in Tables 3-1-1, 3-1-2, 3-2-1, 3-2-2, 4-1-1, and 4-1-2.

[0083] The ionization potentials of the support, the undercoat layer, the compound (α) and the comparative compound were measured using AC-3 (manufactured by Riken Keiki Co., Ltd.). The compound (α) and the comparative compound were each measured individually. The support was measured from the surface of the obtained support, and the undercoat layer was measured from the surface of the undercoat layer after the undercoat layer was formed. The start energy was 4.00 eV, the end energy was 7.00 eV, and the step was 0.05 eV. The evaluation results are shown in Table 3-1-1, Table 3-1-2, Table 3-2-1, Table 3-2-2, Table 4-1-1, and Table 4-1-2. The residual potential and the ionization potential of the undercoat layer were similarly determined by replacing the above photoreceptor 1 with photoreceptors 2 to 76 and photoreceptors 101 to 108. The obtained evaluation results are shown in Tables 3-1-1, 3-1-2, 3-2-1, 3-2-2, 4-1-1, and 4-1-2.

[0084] The disclosure of this embodiment includes the following configuration. (Configuration 1) An electrophotographic photoreceptor having a support, an undercoat layer formed directly on the support, and a photosensitive layer formed on the undercoat layer, When the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more; When the ionization potential of the support is IPs, the IPs is less than the IPu, the undercoat layer contains a compound (α), When the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα satisfy the following relational formula (1): IPs≧IPα-1.0 (1) 1. An electrophotographic photoreceptor comprising: (Configuration 2) The IPs and the IPα satisfy the following relational formula (2): IPs≧IPα(2) 2. The electrophotographic photoreceptor according to claim 1. (Configuration 3) The IPs and the IPα satisfy the following relational formula (3): IPs-IPα ≥ 0.3 (3) 3. The electrophotographic photoreceptor according to configuration 2. (Configuration 4) The electrophotographic photoreceptor according to any one of configurations 1 to 3, wherein the compound (α) is a compound represented by the following formula (α): [ka] (In the formula (α), Ar 1 and Ar 2 each independently represents a substituted or unsubstituted phenyl group. 3 represents an n-valent aromatic group, where n is an integer of 1 to 3. (Configuration 5) 5. The electrophotographic photoreceptor according to any one of Configurations 1 to 4, wherein the undercoat layer contains a cured product of a composition containing a compound represented by the following formula (B1) or (B2): [ka] [ka] (In formulas (B1) and (B2), R 101 ~R 106 and R 201 ~R 210 each independently represents a monovalent group represented by the following formula (C), a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. 101 ~R 106 At least one of, and R 201 ~R 210At least one of the above is a monovalent group represented by the following formula (C). One of the CH2 of the alkyl group may be substituted with O or S, or one of the CH of the alkyl group may be substituted with N. The substituent of the substituted alkyl group is at least one group selected from the group consisting of an aryl group, an alkoxycarbonyl group, a halogen atom, and a hydroxy group. The substituent of the substituted aryl group and the substituted heterocyclic group is at least one group selected from the group consisting of a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, and an alkoxy group. [ka] (In formula (C), at least one of a, b, and c has at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group. l and m each independently represent 0 or 1, and the sum of l and m is 0 or more and 2 or less. a represents an alkylene group having 1 to 6 carbon atoms in the main chain, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a benzyl group, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a phenyl group, and these alkylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. One of the CH2 in the main chain of these alkylene groups may be substituted with O or S, or one of the CH in the main chain of these alkylene groups may be substituted with N. b represents a phenylene group, an alkyl group-substituted phenylene group having from 1 to 6 carbon atoms, a nitro group-substituted phenylene group, a halogen group-substituted phenylene group, or an alkoxy group-substituted phenylene group, and these phenylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. c represents a hydrogen atom, a carboxy group, an alkyl group having 1 to 6 carbon atoms in its main chain, or an alkyl group having 1 to 6 carbon atoms in its main chain substituted with an alkyl group having 1 to 5 carbon atoms, and these alkyl groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. (Configuration 6) The content of the compound (α) is 3.5% by mass or more and 15% by mass or less with respect to the compound represented by the formula (B1) or (B2). 6. The electrophotographic photoreceptor according to configuration 5. (Configuration 7) A process cartridge which integrally supports the electrophotographic photosensitive member according to any one of Configurations 1 to 6 and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, and is detachably attachable to a main body of an electrophotographic apparatus. (Configuration 8) An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of Configurations 1 to 6, a charging unit, an exposing unit, a developing unit, and a transferring unit. [Explanation of symbols]

[0085] 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. An electrophotographic photoreceptor having a support, an undercoat layer formed directly on the support, and a photosensitive layer formed on the undercoat layer, When the ionization potential of the undercoat layer is IPu, the IPu is 6.0 eV or more; When the ionization potential of the support is IPs, the IPs is less than the IPu, the undercoat layer contains a compound (α), When the ionization potential of the compound (α) is IPα, the IPα is 5.0 eV or more and 5.4 eV or less, The IPs and the IPα satisfy the following relational formula (1): IPs≧IPα−1.0 (1) 1. An electrophotographic photoreceptor comprising:

2. The IPs and the IPα satisfy the following relational formula (2): IPs ≧ IPα (2) The electrophotographic photoreceptor according to claim 1 .

3. The IPs and the IPα satisfy the following relational formula (3): IPs-IPα≧0.3 (3) The electrophotographic photoreceptor according to claim 2 .

4. The electrophotographic photoreceptor according to claim 1 , wherein the compound (α) is a compound represented by the following formula (α): 【Chemistry 1】 (In formula (α), Ar １ and Ar ２ each independently represents a substituted or unsubstituted phenyl group. ３ represents an n-valent aromatic group, where n is an integer of 1 to 3. The substituent of the substituted phenyl group is an alkyl group or an alkoxy group.

5. The electrophotographic photoreceptor according to claim 1 , wherein the undercoat layer comprises a cured product of a composition containing a compound represented by the following formula (B1) or (B2): 【Chemistry 2】 【Chemistry 3】 (In formulas (B1) and (B2), R １０１ ~R １０６ and R ２０１ ~R ２１０ each independently represents a monovalent group represented by the following formula (C), a hydrogen atom, a cyano group, a nitro group, a halogen atom, an alkoxycarbonyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. １０１ ~R １０６ At least one of, and R ２０１ ~R ２１０ At least one of the alkyl groups is a monovalent group represented by the following formula (C): ２ may be substituted with O or S, or one of the CH's of the alkyl group may be substituted with N. The substituent of the substituted alkyl group is at least one group selected from the group consisting of an aryl group, an alkoxycarbonyl group, a halogen atom, and a hydroxy group. The substituent of the substituted aryl group and the substituted heterocyclic group is at least one group selected from the group consisting of a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, and an alkoxy group. 【Chemistry 4】 (In formula (C), at least one of a, b, and c has at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group. l and m each independently represent 0 or 1, and the sum of l and m is 0 or more and 2 or less. a represents an alkylene group having 1 to 6 carbon atoms in the main chain, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkyl group having 1 to 6 carbon atoms, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a benzyl group, an alkylene group having 1 to 6 carbon atoms in the main chain substituted with an alkoxycarbonyl group, or an alkylene group having 1 to 6 carbon atoms in the main chain substituted with a phenyl group, and these alkylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. ２ may be substituted with O or S, or one of the CH's in the main chain of these alkylene groups may be substituted with N. b represents a phenylene group, an alkyl group-substituted phenylene group having from 1 to 6 carbon atoms, a nitro group-substituted phenylene group, a halogen group-substituted phenylene group, or an alkoxy group-substituted phenylene group, and these phenylene groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent. c represents a hydrogen atom, a carboxy group, an alkyl group having 1 to 6 carbon atoms in the main chain, or an alkyl group having 1 to 6 carbon atoms in the main chain substituted with an alkyl group having 1 to 5 carbon atoms, and these alkyl groups may have at least one group selected from the group consisting of a hydroxy group, a thiol group, an amino group, and a carboxy group as a substituent.

6. The content of the compound (α) is 3.5% by mass or more and 15% by mass or less with respect to the compound represented by the formula (B1) or (B2). The electrophotographic photoreceptor according to claim 5 .

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

8. 2. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1, a charging means, an exposure means, a developing means and a transfer means.

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