Electrophotographic photoreceptor, process cartridge and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in electrical characteristics and wear resistance.SOLUTION: An electrophotographic photoreceptor comprises: a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer. The charge transport layer contains a charge transport material, at least one of polyester resin having a constitutional unit having an aromatic ring and polycarbonate resin having a constitutional unit having an aromatic ring, and a compound (1) represented by the formula (1) and having a melting point of 40°C or more. In the formula (1), Ar is an aromatic ring which may have a substituent group, L is a single bond, an oxygen atom, or a sulfur atom, R is an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and n is an integer of 1 or more.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an electrophotographic photoreceptor having a surface layer containing a polyester resin having diphenyl ether-4,4'-dicarboxylic acid units and bisphenol units.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor having a surface layer containing a charge transport material and a polyester resin, the polyester resin being, for example, a polyester resin having an isophthalic acid unit and a bisphenol unit.

[0004] Patent Document 3 discloses an electrophotographic photoreceptor in which the surface layer is a charge transport layer, and the surface layer contains (α), (β) and (γ). (α) at ​​least one charge transport material having a predetermined structural formula; (β) At least one compound selected from the group consisting of hexanol, heptanol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, diethylene glycol ethyl methyl ether, ethylene carbonate, propylene carbonate, nitrobenzene, pyrrolidone, N-methylpyrrolidone, methyl benzoate, ethyl benzoate, benzyl acetate, ethyl 3-ethoxypropionate, acetophenone, methyl salicylate, dimethyl phthalate, and sulfolane. (γ) At least one resin selected from the group consisting of polycarbonate resins having a terminal siloxane structure and polyester resins having a terminal siloxane structure.

[0005] Patent Document 4 discloses a method for producing an electrophotographic photoreceptor having a surface layer, in which the coating liquid for the surface layer contains (α), (β), (γ), and (δ). (α) At least one resin selected from the group consisting of polycarbonate resins having no terminal siloxane structures and polyester resins having no terminal siloxane structures. (β) At least one resin selected from the group consisting of polycarbonate resins having a terminal siloxane structure, polyester resins having a terminal siloxane structure, and acrylic resins having a terminal siloxane structure. (γ) At least one solvent selected from the group consisting of toluene and xylene. (δ) A compound with a given structural formula that has a higher boiling point at 1 atmosphere than (γ). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-185373 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-151425 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-137541 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-050699 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to provide an electrophotographic photoreceptor that is superior in electrical properties and abrasion resistance compared to an electrophotographic photoreceptor that has a multilayer photosensitive layer in which the charge transport layer does not contain compound (1), or an electrophotographic photoreceptor that has a single-layer photosensitive layer in which the single-layer photosensitive layer does not contain compound (1). [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects.

[0009] <1> An electrophotographic photoreceptor comprising a conductive substrate and a laminated photosensitive layer disposed on the conductive substrate, the laminated photosensitive layer having a charge generating layer and a charge transport layer, wherein the charge transport layer contains a charge transport material, at least one of a polyester resin having a structural unit with an aromatic ring and a polycarbonate resin having a structural unit with an aromatic ring, and a compound (1) represented by formula (1) and having a melting point of 40°C or higher. <2> the mass ratio of the compound (1) to the total mass of the charge transport layer is 0.1 mass% or more and less than 7.0 mass%; <1> The electrophotographic photoreceptor according to claim 1. <3> An electrophotographic photoreceptor comprising a conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer containing a charge transport material, at least one of a polyester resin having a structural unit with an aromatic ring and a polycarbonate resin having a structural unit with an aromatic ring, and a compound (1) represented by formula (1) and having a melting point of 40°C or higher. <4> the mass ratio of the compound (1) to the total mass of the single-layer photosensitive layer is 0.2 mass% or more and less than 14.0 mass%; <3> The electrophotographic photoreceptor according to claim 1. <5> The compound (1) includes a compound represented by formula (1) in which Ar is an aromatic ring having 6 carbon atoms, L is a single bond, R is a methyl group, and n is an integer of 1 or more. <1> ~ <4> 10. The electrophotographic photoreceptor according to claim 9, wherein the electrophotographic photoreceptor is a <6> The polyester resin having a structural unit having an aromatic ring includes a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). <1> ~ <5> 10. The electrophotographic photoreceptor according to claim 9, wherein the electrophotographic photoreceptor is a <7> The dicarboxylic acid unit (A) represented by formula (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). <6> The electrophotographic photoreceptor according to claim 1. <8> The diol unit (B) represented by formula (B) includes at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8). <6> or <7> The electrophotographic photoreceptor according to claim 1. <9> The polycarbonate resin having a structural unit having an aromatic ring includes a polycarbonate resin (1) having a structural unit (C) represented by formula (C): <1> ~ <8> 10. The electrophotographic photoreceptor according to claim 9, wherein the electrophotographic photoreceptor is a <10> The structural unit (C) represented by formula (C) includes at least one selected from the group consisting of a structural unit (Ca1) represented by formula (Ca1), a structural unit (Ca2) represented by formula (Ca2), a structural unit (Ca3) represented by formula (Ca3), a structural unit (Ca4) represented by formula (Ca4), a structural unit (Ca5) represented by formula (Ca5), a structural unit (Ca6) represented by formula (Ca6), a structural unit (Cb1) represented by formula (Cb2), a structural unit (Cb3) represented by formula (Cb3), a structural unit (Cb4) represented by formula (Cb5), a structural unit (Cb5) represented by formula (Cb6), and a structural unit (Cb6). <9> The electrophotographic photoreceptor according to claim 1. <11> the charge transport material comprises at least one selected from the group consisting of a compound (D1) represented by formula (D1), a compound (D2) represented by formula (D2), a compound (D3) represented by formula (D3), and a compound (D4) represented by formula (D4), <1> ~ <10> 10. The electrophotographic photoreceptor according to claim 9, wherein the electrophotographic photoreceptor is a <12> <1> ~ <11> 10. A process cartridge comprising the electrophotographic photosensitive member according to any one of claims 1 to 9, which is detachably mountable to an image forming apparatus. <13> <1> ~ <11> an electrophotographic photosensitive member according to any one of the preceding items; a charging unit that charges the surface of the electrophotographic photosensitive member; an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photosensitive member; a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image; and a transfer unit that transfers the toner image onto a surface of a recording medium. [Effects of the Invention]

[0010] <1> , <5> , <6> , <7> , <8> , <9> , <10> or <11> According to the invention, an electrophotographic photoreceptor is provided which is superior in electrical properties and abrasion resistance compared to an electrophotographic photoreceptor which has a laminated photosensitive layer and in which the charge transport layer does not contain compound (1). <2> According to the invention, an electrophotographic photoreceptor is provided which is excellent in electrical properties and abrasion resistance compared to an electrophotographic photoreceptor which has a multilayer photosensitive layer and in which the mass proportion of compound (1) in the total mass of the charge transport layer is less than 0.1 mass % or 7.0 mass % or more. <3> , <5> , <6> , <7> , <8> , <9> , <10> or <11> According to the invention, there is provided an electrophotographic photoreceptor which has a single-layer type photosensitive layer and which is excellent in electrical properties and abrasion resistance compared to an electrophotographic photoreceptor which has a single-layer type photosensitive layer that does not contain compound (1). <4> According to the invention, an electrophotographic photoreceptor is provided which is excellent in electrical properties and abrasion resistance compared to an electrophotographic photoreceptor which has a single-layer photosensitive layer and in which the mass proportion of compound (1) relative to the total mass of the single-layer photosensitive layer is less than 0.2 mass % or 14.0 mass % or more. <12> According to the invention, there is provided a process cartridge including an electrophotographic photoreceptor which is superior in electrical properties and wear resistance compared to an electrophotographic photoreceptor in which the charge transport layer or the single-layer type photosensitive layer does not contain compound (1). <13> According to the invention, there is provided an image-forming apparatus including an electrophotographic photoreceptor having excellent electrical properties and wear resistance compared to an electrophotographic photoreceptor in which the charge transport layer or the single-layer photosensitive layer does not contain compound (1). [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photosensitive member according to the first embodiment. [Figure 2] FIG. 6 is a partial cross-sectional view showing an example of a layer structure of an electrophotographic photosensitive member according to a second embodiment. [Figure 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. 10 is a schematic configuration diagram illustrating another example of an image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0023] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0013] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0014] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0015] When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0016] In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0017] In the present disclosure, alkyl groups include straight-chain, branched, and cyclic alkyl groups, unless otherwise specified.

[0018] In the present disclosure, a hydrogen atom in an organic group, aromatic ring, linking group, alkyl group, aryl group, aralkyl group, alkoxy group, or aryloxy group may be substituted with a halogen atom.

[0019] <Electrophotographic photoreceptor> The present disclosure provides a first embodiment and a second embodiment of an electrophotographic photoreceptor (hereinafter also referred to as a "photoreceptor").

[0020] The photoreceptor according to the first embodiment includes a conductive substrate and a laminated photoreceptor layer having a charge generating layer and a charge transport layer disposed on the conductive substrate. The photoreceptor according to the first embodiment may further include other layers (e.g., an undercoat layer, an intermediate layer). In the photoreceptor according to the first embodiment, it is preferable that the charge transport layer is a surface layer.

[0021] The photoreceptor according to the second embodiment includes a conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate. The photoreceptor according to the second embodiment may further include other layers (e.g., an undercoat layer, an intermediate layer). In the photoreceptor according to the second embodiment, the single-layer photosensitive layer is preferably a surface layer.

[0022] Fig. 1 is a partial cross-sectional view schematically illustrating an example of the layer structure of a photoreceptor according to the first embodiment. Photoreceptor 10A shown in Fig. 1 has a laminated photosensitive layer. Photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called function-separated photosensitive layer). Photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 1 and the charge generation layer 3.

[0023] Fig. 2 is a partial cross-sectional view schematically illustrating an example of the layer structure of a photoreceptor according to the second embodiment. The photoreceptor 10B shown in Fig. 2 has a single-layer photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are laminated in this order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 1 and the photosensitive layer 5.

[0024] In the photoreceptor according to the first embodiment, the charge transport layer contains a charge transport material, at least one of a polyester resin having a structural unit with an aromatic ring and a polycarbonate resin having a structural unit with an aromatic ring, and a compound (1) represented by the following formula (1) and having a melting point of 40°C or higher.

[0025] In the photoreceptor according to the second embodiment, the single-layer photosensitive layer contains a charge transport material, at least one of a polyester resin having a structural unit with an aromatic ring and a polycarbonate resin having a structural unit with an aromatic ring, and a compound (1) represented by the following formula (1) and having a melting point of 40°C or higher:

[0026] [ka]

[0027] In formula (1), Ar is an aromatic ring which may have a substituent; L is a single bond, an oxygen atom, or a sulfur atom; R is an alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an aralkyl group having from 7 to 20 carbon atoms; and n is an integer of 1 or greater.

[0028] The melting point of compound (1) is the melting point of compound (1) as a pure substance.

[0029] Hereinafter, when matters common to the first embodiment and the second embodiment are described, both embodiments will be collectively referred to as the present embodiment. When matters common to the charge transport layer and the single-layer type photosensitive layer are described, both layers will be collectively referred to as the photosensitive layer.

[0030] The photoreceptor according to this embodiment has excellent electrical properties and abrasion resistance, and the reason for this is presumed to be as follows.

[0031] Polyester resins and polycarbonate resins containing aromatic ring-containing structural units have molecular attraction due to the interaction between the aromatic rings, which increases the abrasion resistance of the photosensitive layer containing the resin. On the other hand, the charge transport material is less likely to penetrate between the resin molecules, which reduces the dispersibility of the charge transport material and tends to degrade the electrical properties of the photosensitive layer. Because compound (1) is a molecule having an aromatic ring and an ester bond, it is believed to function as a dispersant that disperses the charge transport material in the resin having an aromatic ring. Furthermore, because compound (1) has a melting point of 40°C or higher (in other words, because it is a molecule with low mobility at room temperature), its spatial and relative arrangement in the photosensitive layer is unlikely to change, and it is believed to function as a binder that connects the resin having an aromatic ring and the charge transport material. As a result, the photoreceptor of this embodiment is believed to have excellent electrical properties and wear resistance.

[0032] In the photoreceptor according to the first embodiment, from the viewpoint of excellent electrical properties and abrasion resistance, the mass proportion of compound (1) relative to the total mass of the charge transport layer is preferably 0.1 mass % or more and less than 7.0 mass %, more preferably 0.2 mass % or more and less than 5.0 mass %, and even more preferably 0.4 mass % or more and less than 2.0 mass %.

[0033] In the photoreceptor according to the second embodiment, from the viewpoint of excellent electrical properties and abrasion resistance, the mass proportion of compound (1) relative to the total mass of the single-layer photosensitive layer is preferably 0.2 mass% or more and less than 14.0 mass%, more preferably 0.4 mass% or more and less than 10.0 mass%, and even more preferably 0.8 mass% or more and less than 4.0 mass%.

[0034] In the first embodiment, the mass proportion of the compound (1) contained in the charge transport layer is determined as follows. The photoreceptor is immersed in various solvents (including mixed solvents) to determine the solvent in which the charge transport layer dissolves. The photoreceptor is immersed in a solvent in which the charge transport layer dissolves, and the charge transport layer is extracted. The solvent is removed from the solution from which the charge transport layer was extracted (for example, by concentrating the solution and then vacuum drying), to obtain a mixture of the components that make up the charge transport layer. This mixture is weighed, and this is the mass of the charge transport layer. A predetermined amount of this mixture is taken and dissolved in tetrahydrofuran, and then methanol is added to the solution to a constant volume to reprecipitate the resin. The supernatant after the resin reprecipitation is filtered, and the filtrate is used as the measurement sample for HPLC (High Performance Liquid Chromatography). The area values ​​of the substance corresponding to compound (1) in the chromatogram of the measurement sample are added up, and quantified based on the calibration curve of the standard sample. The mass ratio (mass %) of compound (1) to the mass of the charge transport layer is calculated. In the second embodiment, the above-mentioned "charge transport layer" is replaced with a "single-layer type photosensitive layer" and the measurement is carried out in the same manner.

[0035] The charge transport layer in the first embodiment is preferably formed using a coating liquid containing compound (1), which suppresses aggregation of the resin and charge transport material contained in the coating liquid. The single-layer photosensitive layer in the second embodiment is preferably formed using a coating liquid containing compound (1), which suppresses aggregation of the resin and charge transport material contained in the coating liquid.

[0036] The compound (1), the polyester resin having a structural unit with an aromatic ring, the polycarbonate resin having a structural unit with an aromatic ring, and each layer of the photoreceptor will be described in detail below.

[0037] [Compound (1)] Compound (1) has a melting point of 40° C. or higher. The melting point of compound (1) is the melting point of compound (1) as a pure substance. The melting point of the compound (1) is preferably 60° C. or higher, more preferably 100° C. or higher, from the viewpoint of preventing a decrease in abrasion resistance. From the viewpoint of solubility, the melting point of the compound (1) is preferably 280°C or lower, more preferably 200°C or lower, and even more preferably 160°C or lower.

[0038] Compound (1) is a compound represented by the following formula (1).

[0039] [ka]

[0040] In formula (1), Ar is an aromatic ring which may have a substituent, L is a single bond, an oxygen atom or a sulfur atom, R is an alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon atoms or an aralkyl group having from 7 to 20 carbon atoms, and n is an integer of 1 or more. The n -LC(=O)-O-R may be the same or different.

[0041] The aromatic ring of Ar may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0042] A hydrogen atom on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, etc. When the aromatic ring of Ar is substituted, the substituent is preferably an alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or an alkoxy group having from 1 to 6 carbon atoms.

[0043] L is preferably a single bond or an oxygen atom, more preferably a single bond.

[0044] The alkyl group having 1 to 10 carbon atoms associated with R may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of branched alkyl groups having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups. The alkyl group having 1 to 10 carbon atoms associated with R is preferably a methyl group.

[0045] The aryl group having 6 to 20 carbon atoms related to R may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10, and even more preferably 6. Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthryl group, and a phenanthryl group. The aryl group having 6 to 20 carbon atoms related to R is preferably a phenyl group, a 1-naphthyl group, or a 2-naphthyl group.

[0046] The alkyl group in the aralkyl group having 7 to 20 carbon atoms associated with R may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. The aryl group in the aralkyl group having 7 to 20 carbon atoms associated with R may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10, and still more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathymethyl group, and a phenyl-cyclopentylmethyl group. As the aralkyl group having 7 to 20 carbon atoms related to R, a benzyl group is preferred.

[0047] n is an integer of 1 or more, and is a number corresponding to the number of carbon atoms in the aromatic ring of Ar. n is preferably an integer of 1 or more and 6 or less, more preferably an integer of 1 or more and 3 or less, and even more preferably 1 or 2.

[0048] In formula (1), n ​​Rs are each independently preferably a methyl group, an ethyl group, a phenyl group, a 1-naphthyl group, a 2-naphthyl group, or a benzyl group, and more preferably a methyl group or a phenyl group.

[0049] The compound (1) preferably includes at least one selected from the group consisting of a compound (1a) represented by the following formula (1a), a compound (1b) represented by the following formula (1b), a compound (1c) represented by the following formula (1c), and a compound (1d) represented by the following formula (1d):

[0050] [ka]

[0051] In formula (1a), R 11 is an alkyl group having 1 to 10 carbon atoms, and n 11 is an integer between 1 and 6. 11 The alkyl group having 1 to 10 carbon atoms in the formula (R) may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. 11 is preferably a methyl group. 11 is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 2 or 3.

[0052] [ka]

[0053] In formula (1b), R 21 and R 22 are each independently an alkyl group having 1 to 10 carbon atoms, and n 21 and n 22 are each independently an integer of 0 to 5, 21 +n 22 ≧1. R 21 and R 22 The alkyl group having 1 to 10 carbon atoms in the formula (R) may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. 21 and R 22 is preferably a methyl group. 21and n 22 are each independently preferably 1 or more and 3 or less, more preferably 1 or 2, and even more preferably 1.

[0054] [ka]

[0055] In formula (1c), R 31 and R 32 are each independently an alkyl group having 1 to 10 carbon atoms, and n 31 and n 32 are each independently an integer of 0 to 4, 31 +n 32 ≧1. R 31 and R 32 The alkyl group having 1 to 10 carbon atoms in the formula (R) may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. 31 and R 32 is preferably a methyl group. 31 and n 32 are each independently preferably 1 or more and 3 or less, more preferably 1 or 2, and even more preferably 1.

[0056] [ka]

[0057] In formula (1d), Ar 41 is a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and R 41 and R 42 are each independently an alkylene group having 1 to 3 carbon atoms, and m 41 , m 42 and m 43 are each independently 0 or 1. 41 When is 1, R 41 is preferably a methylene group or an ethylene group, more preferably a methylene group. 42 When is 1, R 42is preferably a methylene group or an ethylene group, more preferably a methylene group.

[0058] Specific examples of compound (1) are shown below, but compound (1) is not limited thereto.

[0059] [ka]

[0060] [Table 1]

[0061] The most preferred compound (1) is dimethyl terephthalate.

[0062] In the photoreceptor according to the first embodiment, the content of compound (1) in the charge transport layer is preferably 0.1 to 7.5 parts by weight, more preferably 0.2 to 5.3 parts by weight, and even more preferably 0.4 to 2.0 parts by weight, per 100 parts by weight of the charge transport material.

[0063] In the photoreceptor according to the second embodiment, the content of compound (1) in the single-layer photosensitive layer is preferably 0.2 parts by mass or more and 16.3 parts by mass or less, more preferably 0.4 parts by mass or more and 11.1 parts by mass or less, and even more preferably 0.8 parts by mass or more and 4.2 parts by mass or less, relative to 100 parts by mass of the charge transport material.

[0064] [Polyester resin having a structural unit with an aromatic ring] As the polyester resin having a structural unit having an aromatic ring, a polyester resin (1) having at least a dicarboxylic acid unit (A) and a diol unit (B) is preferred. The polyester resin (1) may contain a dicarboxylic acid unit other than the dicarboxylic acid unit (A). The polyester resin (1) may contain a diol unit other than the diol unit (B).

[0065] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0066] [ka]

[0067] In formula (A), Ar A1 and Ar A2 each independently represents an aromatic ring which may have a substituent, and L A is a single bond or a divalent linking group, and n A1 is 0, 1 or 2.

[0068] Ar A1 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0069] Ar A1 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. A1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0070] Ar A2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0071] Ar A2 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. A2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0072] L A When is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Ra 1 )(Ra 2 )-, where Ra 1 and Ra 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; 1 and Ra 2 may be bonded to form a cyclic alkyl group.

[0073] Ra 1 and Ra 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0074] Ra 1 and Ra 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0075] Ra 1 and Ra 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0076] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the following formula (A1), a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4).

[0077] [ka]

[0078] In formula (A1), n 101 is an integer between 0 and 4, and n 101 Ra 101 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 101 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0079] [ka]

[0080] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra 202 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 201 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 202 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0081] [ka]

[0082] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 302 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0083] [ka]

[0084] In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401 is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0085] Ra in formula (A1) 101 , Ra in formula (A2) 201 and Ra 202 , Ra in formula (A3) 301 and Ra 302 and Ra in formula (A4) 401 Since the specific and preferred embodiments of Ra are the same as those of 101 , Ra 201 , Ra202 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0086] The alkyl group having 1 to 10 carbon atoms represented by Ra may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of branched alkyl groups having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0087] The aryl group having 6 to 12 carbon atoms for Ra may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0088] The alkyl group in the alkoxy group having 1 to 6 carbon atoms, represented by Ra, may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0089] Specific examples of the dicarboxylic acid unit (A1) include dicarboxylic acid units (A1-1) to (A1-9), but the dicarboxylic acid unit (A1) is not limited thereto.

[0090] [ka]

[0091] Specific examples of the dicarboxylic acid unit (A2) include dicarboxylic acid units (A2-1) to (A2-3), but the dicarboxylic acid unit (A2) is not limited thereto.

[0092] [ka]

[0093] Specific examples of the dicarboxylic acid unit (A3) include dicarboxylic acid units (A3-1) and (A3-2), but the dicarboxylic acid unit (A3) is not limited thereto.

[0094] [ka]

[0095] Specific examples of the dicarboxylic acid unit (A4) include dicarboxylic acid units (A4-1) to (A4-3), but the dicarboxylic acid unit (A4) is not limited thereto.

[0096] [ka]

[0097] As the dicarboxylic acid unit (A), the above specific examples (A1-1), (A1-7), (A2-3), (A3-2) and (A4-3) are preferred, with (A2-3) being the most preferred.

[0098] The total mass proportion of the dicarboxylic acid units (A1) to (A4) in the polyester resin (1) is preferably 15 mass % or more and 60 mass % or less. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 15% by mass or more, the abrasion resistance of the photosensitive layer is good. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 20% by mass or more, and even more preferably 25% by mass or more. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 60 mass% or less, peeling of the photosensitive layer can be suppressed. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 55 mass% or less, and even more preferably 50 mass% or less. The dicarboxylic acid units (A1) to (A4) contained in the polyester resin (1) may be of one type or two or more types.

[0099] Examples of the dicarboxylic acid units (A) other than the dicarboxylic acid units (A1) to (A4) include aliphatic dicarboxylic acid units (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The polyester resin (1) may contain one or more types of these dicarboxylic acid units.

[0100] The dicarboxylic acid unit (A) contained in the polyester resin (1) may be of one type or of two or more types.

[0101] The diol unit (B) is a structural unit represented by the following formula (B).

[0102] [ka]

[0103] In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent, and L B is a single bond, an oxygen atom, a sulfur atom, or -C(Rb 1 )(Rb 2 )- and n B1 is 0, 1 or 2. Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0104] Ar B1 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0105] Ar B1 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0106] Ar B2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0107] Ar B2 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0108] Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, more preferably 1 to 14 carbon atoms, and even more preferably 1 to 10 carbon atoms.

[0109] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0110] Rb 1 and Rb 2The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0111] The diol unit (B) preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B3) represented by the following formula (B3), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), a diol unit (B6) represented by the following formula (B6), a diol unit (B7) represented by the following formula (B7), and a diol unit (B8) represented by the following formula (B8).

[0112] [ka]

[0113] In formula (B1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0114] Rb 101 The number of carbon atoms in the branched alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 101Specific examples of the aryl group include an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0115] [ka]

[0116] In formula (B2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0117] Rb 102 The carbon number of the linear alkyl group having 4 to 20 carbon atoms in the formula (Rb) is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples of the alkyl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0118] [ka]

[0119] In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0120] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 213 The alkyl group in the alkoxy group having from 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 4 carbon atoms is preferably from 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0121] [ka]

[0122] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb804 and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0123] Rb 104 The alkyl group having 1 to 3 carbon atoms in the formula (Rb) may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably has 1 carbon atom. 104 Specific examples of the group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0124] [ka]

[0125] In formula (B5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0126] Ar 105 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105The aryl group in the aralkyl group having 7 to 20 carbon atoms according to the above formula may be either monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of aralkyl groups having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathymethyl group, and a phenyl-cyclopentylmethyl group.

[0127] [ka]

[0128] In formula (B6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is 5 or 6; Rb 406 , Rb 506 , Rb 806 and Rb 906 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0129] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 116 and Rb 216The alkyl group in the alkoxy group having from 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 4 carbon atoms is preferably from 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0130] [ka]

[0131] In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0132] [ka]

[0133] In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0134] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific and preferred embodiments of Rb are the same as those of Rb, 201 , Rb202 , Rb 204 and Rb 205 "Rb 200 " is collectively referred to as ".

[0135] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably 1 carbon atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0136] Rb in formula (B1) 401 , Rb in formula (B2) 402 , Rb in formula (B3) 403 , Rb in formula (B4) 404 , Rb in formula (B5) 405 , Rb in formula (B6) 406 , Rb in formula (B7) 407 and Rb of formula (B8) 408 Since the specific and preferred embodiments of Rb are the same as those of Rb, 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 "Rb 400 " is collectively referred to as ".

[0137] Rb 400 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0138] Rb 400 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0139] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0140] Rb in formula (B1) 501 , Rb in formula (B2) 502 , Rb in formula (B3) 503 , Rb in formula (B4) 504 , Rb in formula (B5) 505 , Rb in formula (B6) 506 , Rb in formula (B7) 507 and Rb of formula (B8) 508 Since the specific and preferred embodiments of Rb are the same as those of Rb, 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 "Rb 500 " is collectively referred to as ".

[0141] Rb 500 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0142] Rb 500 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0143] Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0144] Rb in formula (B1) 801 , Rb in formula (B2)802 , Rb in formula (B3) 803 , Rb in formula (B4) 804 , Rb in formula (B5) 805 , Rb in formula (B6) 806 , Rb in formula (B7) 807 and Rb of formula (B8) 808 Since the specific and preferred embodiments of Rb are the same as those of Rb, 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 "Rb 800 " is collectively referred to as ".

[0145] Rb 800 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0146] Rb 800 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0147] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0148] Rb in formula (B1) 901 , Rb in formula (B2) 902 , Rb in formula (B3) 903 , Rb in formula (B4) 904 , Rb in formula (B5) 905 , Rb in formula (B6) 906 , Rb in formula (B7) 907 and Rb of formula (B8) 908 Since the specific and preferred embodiments of Rb are the same as those of Rb, 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb 907 and Rb 908 "Rb 900 " is collectively referred to as ".

[0149] Rb 900 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0150] Rb 900 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0151] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0152] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0153] [ka]

[0154] Specific examples of the diol unit (B2) include diol units (B2-1) to (B2-11), but the diol unit (B2) is not limited thereto.

[0155] [ka]

[0156] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0157] [ka]

[0158] Specific examples of the diol unit (B4) include diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0159] [ka]

[0160] Specific examples of the diol unit (B5) include diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0161] [ka]

[0162] Specific examples of the diol unit (B6) include diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0163] [ka]

[0164] Specific examples of the diol unit (B7) include diol units (B7-1) to (B7-3), but the diol unit (B7) is not limited thereto.

[0165] [ka]

[0166] Specific examples of the diol unit (B8) include diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0167] [ka]

[0168] The diol unit (B) contained in the polyester resin (1) may be one type or two or more types.

[0169] The mass proportion of the diol units (B) in the polyester resin (1) is preferably 25 mass % or more and 80 mass % or less. When the mass proportion of the diol units (B) is 25 mass% or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass proportion of the diol units (B) is more preferably 30 mass% or more, and even more preferably 35 mass% or more. When the mass proportion of the diol unit (B) is 80 mass% or less, the solubility in the coating solution for forming the photosensitive layer can be maintained and the abrasion resistance can be improved. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 75 mass% or less, and even more preferably 70 mass% or less.

[0170] Examples of diol units other than the diol units (B) include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0171] The ends of the polyester resin (1) may be capped or modified with a terminal capping agent or a molecular weight modifier used during production. Examples of the terminal capping agent or molecular weight modifier include monohydric phenols, monohydric acid chlorides, monohydric alcohols, and monocarboxylic acids. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, and 2-phenyl-2-(3-hydroxyphenyl)propane. Examples of the monovalent acid chloride include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetic acid chloride, butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and substituted versions thereof. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monocarboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0172] The weight average molecular weight of the polyester resin (1) is preferably 30,000 or more and 300,000 or less, more preferably 40,000 or more and 250,000 or less, and even more preferably 50,000 or more and 200,000 or less. The molecular weight of the polyester resin (1) is a molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC), which uses tetrahydrofuran as an eluent.

[0173] Examples of methods for producing the polyester resin (1) include interfacial polymerization, solution polymerization, and melt polymerization.

[0174] [Polycarbonate resin having a structural unit with an aromatic ring] As the polycarbonate resin having a structural unit with an aromatic ring, a polycarbonate resin (1) having the structural unit (C) is preferred.

[0175] The structural unit (C) is a structural unit represented by the following formula (C).

[0176] [ka]

[0177] In formula (C), Ar C1 and Ar C2 each independently represents an aromatic ring which may have a substituent, and L C is a single bond or a divalent linking group, and n C1 is 0, 1 or 2.

[0178] Ar C1 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0179] Ar C1 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. C1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0180] Ar C2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred.

[0181] Ar C2 The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. C2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0182] L C When R is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Rc 1 )(Rc 2 )-, where Rc 1 and Rc 2 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; 1 and Rc 2 may be bonded to form a cyclic alkyl group.

[0183] Rc 1 and Rc 2The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, more preferably 1 to 14 carbon atoms, and even more preferably 1 to 10 carbon atoms.

[0184] Rc 1 and Rc 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0185] Rc 1 and Rc 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rc 1 and Rc 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0186] The structural unit (C) preferably includes at least one selected from the group consisting of a structural unit (Ca1) represented by the following formula (Ca1), a structural unit (Ca2) represented by the following formula (Ca2), a structural unit (Ca3) represented by the following formula (Ca3), a structural unit (Ca4) represented by the following formula (Ca4), a structural unit (Ca5) represented by the following formula (Ca5), a structural unit (Ca6) represented by the following formula (Ca6), a structural unit (Cb1) represented by the following formula (Cb2), a structural unit (Cb3) represented by the following formula (Cb3), a structural unit (Cb4) represented by the following formula (Cb4), a structural unit (Cb5) represented by the following formula (Cb5), and a structural unit (Cb6) represented by the following formula (Cb6).

[0187] [ka]

[0188] In formula (Ca1), n 101 is an integer between 0 and 4, and n 101 Ra 101 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca1) 101 and n 101 are the Ra in formula (A1), respectively. 101 and n 101 It has the same meaning and specific form as above.

[0189] [ka]

[0190] In formula (Ca2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra 202 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca2) 201 , Ra 202 , n 201 and n 202 are the Ra in formula (A2), respectively. 201 , Ra 202 , n 201 and n 202 It has the same meaning and specific form as above.

[0191] [ka]

[0192] In formula (Ca3), n 301 and n 302 are each independently an integer of 0 to 4,301 Ra 301 and n 302 Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca3) 301 , Ra 302 , n 301 and n 302 are the Ra in equation (A3), respectively. 301 , Ra 302 , n 301 and n 302 It has the same meaning and specific form as above.

[0193] [ka]

[0194] In formula (Ca4), n 401 is an integer between 0 and 6, and n 401 Ra 401 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca4) 401 and n 401 are the Ra in formula (A4), respectively. 401 and n 401 It has the same meaning and specific form as above.

[0195] [ka]

[0196] In formula (Ca5), Ra 405 , Ra 505 , Ra 805 and Ra 905 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Ra in formula (Ca5) 405 , Ra505 , Ra 805 and Ra 905 are Rb in formula (B7), respectively. 407 , Rb 507 , Rb 807 and Rb 907 It has the same meaning and specific form as above.

[0197] [ka]

[0198] In formula (Ca6), Ra 406 , Ra 506 , Ra 806 and Ra 906 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Ra in formula (Ca6) 406 , Ra 506 , Ra 806 and Ra 906 are Rb in formula (B8), respectively. 408 , Rb 508 , Rb 808 and Rb 908 It has the same meaning and specific form as above.

[0199] [ka]

[0200] In formula (Cb1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb1) 101 , Rb 201 , Rb401 , Rb 501 , Rb 801 and Rb 901 are Rb in formula (B1), respectively. 101 , Rb 201 , Rb 401 , Rb 501 , Rb 801 and Rb 901 It has the same meaning and specific form as above.

[0201] [ka]

[0202] In formula (Cb2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb2) 102 , Rb 202 , Rb 402 , Rb 502 , Rb 802 and Rb 902 are Rb in formula (B2), respectively. 102 , Rb 202 , Rb 402 , Rb 502 , Rb 802 and Rb 902 It has the same meaning and specific form as above.

[0203] [ka]

[0204] In formula (Cb3), Rb 113 and Rb 213are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb3) 113 , Rb 213 , d, Rb 403 , Rb 503 , Rb 803 and Rb 903 are Rb in formula (B3), respectively. 113 , Rb 213 , d, Rb 403 , Rb 503 , Rb 803 and Rb 903 It has the same meaning and specific form as above.

[0205] [ka]

[0206] In formula (Cb4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb4) 104 , Rb 204 , Rb 404 , Rb 504 , Rb 804 and Rb 904 are Rb in formula (B4), respectively. 104 , Rb 204 , Rb 404 , Rb 504 , Rb 804 and Rb904 It has the same meaning and specific form as above.

[0207] [ka]

[0208] In formula (Cb5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Ar in formula (Cb5) 105 , Rb 205 , Rb 405 , Rb 505 , Rb 805 and Rb 905 respectively represent Ar in formula (B5) 105 , Rb 205 , Rb 405 , Rb 505 , Rb 805 and Rb 905 It has the same meaning and specific form as above.

[0209] [ka]

[0210] In formula (Cb6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is 5 or 6; Rb 406 , Rb 506 , Rb 806 and Rb 906are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb6) 116 , Rb 216 , e, Rb 406 , Rb 506 , Rb 806 and Rb 906 are Rb in formula (B6), respectively. 116 , Rb 216 , e, Rb 406 , Rb 506 , Rb 806 and Rb 906 It has the same meaning and specific form as above.

[0211] Specific examples of the structural unit (Ca1) include structural units (Ca1-1) to (Ca1-9), but the structural unit (Ca1) is not limited to these.

[0212] [ka]

[0213] Specific examples of the structural unit (Ca2) include structural units (Ca2-1) to (Ca2-3), but the structural unit (Ca2) is not limited to these.

[0214] [ka]

[0215] Specific examples of the structural unit (Ca3) include structural units (Ca3-1) and (Ca3-2), but the structural unit (Ca3) is not limited to these.

[0216] [ka]

[0217] Specific examples of the structural unit (Ca4) include structural units (Ca4-1) to (Ca4-3), but the structural unit (Ca4) is not limited to these.

[0218] [ka]

[0219] Specific examples of the structural unit (Ca5) include structural units (Ca5-1) to (Ca5-3), but the structural unit (Ca5) is not limited to these.

[0220] [ka]

[0221] Specific examples of the structural unit (Ca6) include structural units (Ca6-1) to (Ca6-3), but the structural unit (Ca6) is not limited to these.

[0222] [ka]

[0223] Specific examples of the structural unit (Cb1) include structural units (Cb1-1) to (Cb1-6), but the structural unit (Cb1) is not limited to these.

[0224] [ka]

[0225] Specific examples of the structural unit (Cb2) include structural units (Cb2-1) to (Cb2-11) shown below, but the structural unit (Cb2) is not limited to these.

[0226] [ka]

[0227] Specific examples of the structural unit (Cb3) include structural units (Cb3-1) to (Cb3-4), but the structural unit (Cb3) is not limited to these.

[0228] [ka]

[0229] Specific examples of the structural unit (Cb4) include structural units (Cb4-1) to (Cb4-7), but the structural unit (Cb4) is not limited to these.

[0230] [ka]

[0231] Specific examples of the structural unit (Cb5) include structural units (Cb5-1) to (Cb5-6), but the structural unit (Cb5) is not limited to these.

[0232] [ka]

[0233] Specific examples of the structural unit (Cb6) include structural units (Cb6-1) to (Cb6-4), but the structural unit (Cb6) is not limited to these.

[0234] [ka]

[0235] The structural unit (C) contained in the polycarbonate resin (1) may be one type or two or more types.

[0236] The polycarbonate resin (1) may contain other structural units in addition to the structural unit (C). Examples of such other structural units include a structural unit derived from an aliphatic diol (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol) and phosgene, and a structural unit derived from an alicyclic diol (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A) and phosgene. The polycarbonate resin (1) may contain one or more of these structural units.

[0237] The mass proportion of the structural unit (C) in the polycarbonate resin (1) is preferably from 80 to 100 mass%, more preferably from 90 to 100 mass%, and even more preferably from 95 to 100 mass%.

[0238] The polycarbonate resin (1) preferably includes, as the structural unit (C), at least one selected from the group consisting of the structural unit (Cb1), the structural unit (Cb2), the structural unit (Cb3), the structural unit (Cb4), the structural unit (Cb5), the structural unit (Cb6), the structural unit (Cb7), and the structural unit (Cb8). The total mass proportion of the structural units (Cb1), (Cb2), (Cb3), (Cb4), (Cb5), (Cb6), (Cb7), and (Cb8) in the polycarbonate resin (1) is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0239] The weight average molecular weight of the polycarbonate resin (1) is preferably 40,000 or more and 200,000 or less, more preferably 6 or more and 180,000 or less, and even more preferably 80,000 or more and 160,000 or less. The molecular weight of the polycarbonate resin (1) is a polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography). GPC uses tetrahydrofuran as an eluent.

[0240] The polycarbonate resin (1) can be produced by an interfacial polymerization method, a solution polymerization method, a melt polymerization method, or the like.

[0241] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is less than Ωcm.

[0242] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm inclusive in order to suppress interference fringes that occur when irradiated with laser light. When incoherent light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate by suppressing defects caused by surface irregularities.

[0243] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, which involves pressing the conductive substrate against a rotating grinding wheel and continuously grinding the substrate; and anodizing.

[0244] As a method for roughening the surface, there may be mentioned a method in which, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0245] Anodizing is a surface roughening treatment that uses a metallic (e.g., aluminum) conductive substrate as the anode and anodizes it in an electrolyte solution to form an oxide film on the surface of the conductive substrate. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active in its original state, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are sealed by volume expansion caused by hydration in pressurized steam or boiling water (with the addition of a metal salt such as nickel), converting the film into a more stable hydrated oxide.

[0246] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm, inclusive, and within this range, the film tends to exhibit barrier properties against injection and also tends to suppress an increase in residual potential due to repeated use.

[0247] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acidic treatment solution is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, with the total concentration of these acids preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0248] The boehmite treatment is carried out, for example, by immersing the steel sheet in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the steel sheet with heated steam at 90°C to 120°C for 5 to 60 minutes. The coating film preferably has a thickness of 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution with low coating solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0249] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0250] For example, inorganic particles have a powder resistance (volume resistivity) of 1×10 2 Ωcm or more 1×10 11 Examples include inorganic particles with a particle size of Ωcm or less. Among these, inorganic particles having the above resistance value are preferably metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0251] The specific surface area of ​​inorganic particles measured by the BET method is, for example, 10 m 2 / g or more is preferable. The volume average particle size of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

[0252] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

[0253] The inorganic particles may be surface-treated, and two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0254] Examples of the surface treatment agent include a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, a surfactant, etc. In particular, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0255] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0256] Two or more silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0257] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

[0258] The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0259] Here, it is preferable that the undercoat layer contains an electron-accepting compound (acceptor compound) together with the inorganic particles, from the viewpoint of improving the long-term stability of the electrical properties and the carrier blocking property.

[0260] Examples of electron-accepting compounds include electron-transporting substances such as quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone. In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure, such as a hydroxyanthraquinone compound, an aminoanthraquinone compound, or an aminohydroxyanthraquinone compound, and specifically, for example, anthraquinone, alizarin, quinizarin, anthrarphine, or purpurin.

[0261] The electron-accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surfaces of the inorganic particles.

[0262] The electron-accepting compound can be attached to the surface of the inorganic particles by, for example, a dry method or a wet method.

[0263] The dry method is a method in which, while stirring inorganic particles using a mixer or the like with high shear force, an electron-accepting compound is added dropwise, either directly or dissolved in an organic solvent, or sprayed together with dry air or nitrogen gas to adhere the electron-accepting compound to the surface of the inorganic particles. The electron-accepting compound is preferably added dropwise or sprayed at a temperature below the boiling point of the solvent. After the electron-accepting compound has been added dropwise or sprayed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as they achieve electrophotographic properties.

[0264] The wet method involves dispersing inorganic particles in a solvent using, for example, stirring, ultrasonic waves, a sand mill, an attritor, or a ball mill, while adding an electron-accepting compound. The mixture is stirred or dispersed, and then the solvent is removed to adhere the electron-accepting compound to the surfaces of the inorganic particles. The solvent can be removed, for example, by filtration or distillation. After solvent removal, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound. Examples of such methods include a method of removing the moisture by stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0265] The attachment of the electron-accepting compound may be carried out before or after the inorganic particles are surface-treated with a surface-treating agent, or the attachment of the electron-accepting compound and the surface treatment with a surface-treating agent may be carried out simultaneously.

[0266] The content of the electron-accepting compound is, for example, 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less, based on the inorganic particles.

[0267] Examples of binder resins used in the undercoat layer include known polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents. Examples of binder resins used in the undercoat layer include charge transporting resins having charge transporting groups, conductive resins (such as polyaniline), and the like.

[0268] Among these, the binder resin used in the undercoat layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and in particular, a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, and epoxy resins, and polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins with a curing agent is preferred. When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0269] The undercoat layer may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of additives include known materials such as polycyclic condensation and azo electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Silane coupling agents are used for the surface treatment of inorganic particles as described above, and may also be added to the undercoat layer as an additive.

[0270] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0271] Examples of zirconium chelate compounds include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0272] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-normal-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0273] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0274] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0275] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of polishing methods include buffing, sandblasting, wet honing, and grinding.

[0276] The formation of the undercoat layer is not particularly limited, and a known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating liquid for forming the undercoat layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0277] Examples of solvents for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0278] Examples of a method for dispersing inorganic particles when preparing a coating liquid for forming an undercoat layer include known methods such as using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0279] Examples of a method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0280] The thickness of the undercoat layer is set, for example, preferably at least 15 μm, more preferably in the range of from 20 μm to 50 μm.

[0281] [Middle layer] An intermediate layer may be further provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (such as polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0282] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0283] The formation of the intermediate layer is not particularly limited, and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating liquid for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it if necessary. The coating method for forming the intermediate layer may be a conventional method such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, or curtain coating.

[0284] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm, and the intermediate layer may also be used as an undercoat layer.

[0285] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable for use with an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0286] Examples of the charge generating material include azo pigments such as bisazo and trisazo; fused-ring aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0287] Among these, in order to be compatible with laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material, and more specifically, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine is more preferable.

[0288] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include fused ring aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0289] The above charge-generating materials may also be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm. However, from the viewpoint of resolution, when using a thin photosensitive layer of 20 μm or less, the electric field strength in the photosensitive layer becomes high, and charge injection from the substrate can easily cause a decrease in charging, resulting in image defects known as black spots. This problem becomes more pronounced when using charge-generating materials that are p-type semiconductors, such as trigonal selenium and phthalocyanine pigments, that are prone to generating dark current.

[0290] In contrast, when an n-type semiconductor such as a fused ring aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is less likely to occur, and image defects known as black spots can be suppressed even when the material is made into a thin film. The n-type is determined by the polarity of the photocurrent that flows using the commonly used time-of-flight method, and those that easily pass electrons as carriers rather than holes are considered n-type.

[0291] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (e.g., polycondensation product of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, etc. Here, "insulating" means a material having a volume resistivity of 1×10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0292] The compounding ratio of the charge generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass.

[0293] The charge generating layer may contain other known additives.

[0294] The formation of the charge generation layer is not particularly limited, and a known formation method can be used. For example, the charge generation layer can be formed by forming a coating film of a coating liquid for forming the charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer can also be formed by vapor deposition of the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a fused ring aromatic pigment or a perylene pigment is used as the charge generation material.

[0295] Examples of solvents for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0296] Methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming the charge generating layer include, for example, media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by passing through a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0297] Examples of methods for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0298] The thickness of the charge generating layer is set, for example, preferably in the range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0299] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin, or may be a layer containing a polymer charge transport material.

[0300] Examples of charge transport materials include electron transport compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of charge transport materials also include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0301] Examples of polymer charge transport materials include known compounds having charge transport properties, such as poly-N-vinylcarbazole and polysilane. Polyester-based polymer charge transport materials are preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0302] Examples of the charge transport material or polymeric charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, paragraphs 0078 to 0080 of Japanese Patent Application Laid-Open No. 2021-117377, paragraphs 0046 to 0048 of Japanese Patent Application Laid-Open No. 2019-035900, paragraphs 0052 to 0053 of Japanese Patent Application Laid-Open No. 2019-012141, paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-071565, and paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-015223 Examples of the compounds include those described in paragraphs 0101 to 0110 of JP 2013-097300 A, paragraph 0116, paragraphs 0309 to 0316 of WO 2019 / 070003 A, paragraphs 0103 to 0107 of JP 2018-159087 A, and paragraphs 0102 to 0113 of JP 2021-148818 A.

[0303] From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a compound (D1) represented by the following formula (D1), a compound (D2) represented by the following formula (D2), a compound (D3) represented by the following formula (D3), and a compound (D4) represented by the following formula (D4).

[0304] [ka]

[0305] In formula (D1), Ar T1 , Ar T2 and Ar T3 are each independently an aryl group, -C6H4-C(R T4 )=C(RT5 )(R T6 ) or -CH-CH=CH-CH=C(R T7 )(R T8 ) is R T4 , R T5 , R T6 , R T7 and R T8 R is independently a hydrogen atom, an alkyl group, or an aryl group. T5 and R T6 When is an aryl group, the aryl groups are connected to each other by -C(R 51 )(R 52 )- and / or -C(R 61 )=C(R 62 R 51 , R 52 , R 61 and R 62 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0306] The group in formula (D1) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0307] From the viewpoint of charge mobility, the compound (D1) is preferably an aryl group or —CH—CH═CH—CH═C(R T7 )(R T8 ) is preferred, and a compound (D'1) represented by the following formula (D'1) is more preferred.

[0308] [ka]

[0309] In formula (D'1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132are each independently a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0310] [ka]

[0311] In formula (D2), R T201 , R T202 , R T211 and R T212 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ) is R T21 , R T22 , R T23 , R T24 and R T25 R is independently a hydrogen atom, an alkyl group, or an aryl group. T221 and R T222 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2.

[0312] The group in formula (D2) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0313] From the viewpoint of charge mobility, the compound (D2) is preferably an alkyl group, an aryl group, or a -CH=CH-CH=C(R T24 )(R T25) is preferred, and the compound having at least one alkyl group, aryl group, or -CH=CH-CH=C(R T24 )(R T25 ) is more preferred.

[0314] [ka]

[0315] In formula (D3), R T301 , R T302 , R T311 and R T312 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ) is R T31 , R T32 , R T33 , R T34 and R T35 R is independently a hydrogen atom, an alkyl group, or an aryl group. T321 , R T322 and R T331 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2.

[0316] The group in formula (D3) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0317] [ka]

[0318] In formula (D4), R T401 , R T402 , R T411 and R T412 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ) is R T41 , R T42 , R T43 , R T44 and R T45 R is independently a hydrogen atom, an alkyl group, or an aryl group. T421 , R T422 and R T431 are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 are each independently 0, 1, or 2.

[0319] The group in formula (D4) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0320] The content of the charge transport material in the charge transport layer is preferably 20% by mass or more and 70% by mass or less based on the total mass of the charge transport layer.

[0321] The charge transport layer preferably contains at least a polyester resin (1) and / or a polycarbonate resin (1) as a binder resin. The total proportion of the polyester resin (1) and the polycarbonate resin (1) in the total amount of the binder resin contained in the charge transport layer is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0322] The charge transport layer may contain a binder resin other than the polyester resin (1) and the polycarbonate resin (1). Examples of the other binder resin include polyester resins other than the polyester resin (1), polycarbonate resins other than the polycarbonate resin (1), methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, and polysilanes. These binder resins may be used alone or in combination of two or more.

[0323] The charge transport layer may contain other known additives, such as antioxidants, leveling agents, antifoaming agents, fillers, and viscosity modifiers.

[0324] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it if necessary.

[0325] Examples of solvents for preparing the coating solution for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination.

[0326] Examples of a coating method for applying the coating liquid for forming the charge transport layer onto the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0327] The average thickness of the charge transport layer is preferably from 5 μm to 60 μm, more preferably from 10 μm to 55 μm, and even more preferably from 15 μm to 50 μm.

[0328] [Single-layer photosensitive layer] The single-layer photosensitive layer (charge generation / charge transport layer) is a layer containing a charge generation material, a charge transport material, a binder resin, and, if necessary, other additives. These materials are the same as those described for the charge generation layer and the charge transport layer.

[0329] The single-layer photosensitive layer preferably contains at least a polyester resin (1) and / or a polycarbonate resin (1) as a binder resin. The total proportion of the polyester resin (1) and the polycarbonate resin (1) in the total amount of the binder resin contained in the single-layer photosensitive layer is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0330] The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass to 10% by mass, and more preferably 0.8% by mass to 5% by mass, based on the total solid content.

[0331] The content of the charge transport material contained in the single-layer photosensitive layer is preferably 40% by mass or more and 60% by mass or less based on the total solid content.

[0332] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer.

[0333] The average thickness of the single-layer photosensitive layer is preferably from 5 μm to 60 μm, more preferably from 10 μm to 55 μm, and even more preferably from 15 μm to 50 μm.

[0334] [Protective layer] A protective layer may be provided on the photosensitive layer as needed, for example, to prevent chemical changes in the photosensitive layer when charged, or to further improve the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a layer made of a cured film (crosslinked film) as the protective layer. Examples of such a layer include the following layers 1) and 2).

[0335] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer containing a polymer or crosslinked product of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material that does not have a charge transport skeleton and has a reactive group (i.e., a layer containing a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material).

[0336] The reactive group of the reactive group-containing charge transport material may be a chain polymerizable group, an epoxy group, -OH, -OR (wherein R represents an alkyl group), -NH2, -SH, -COOH, or -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R Q2 represents a hydrogen atom, an alkyl group or a trialkylsilyl group, and Qn represents an integer of 1 to 3.

[0337] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specific examples include groups containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among these, a group containing at least one selected from a vinyl group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof is preferred as the chain polymerizable group because of its excellent reactivity.

[0338] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it has a known structure in electrophotographic photoreceptors, and examples thereof include a skeleton derived from a nitrogen-containing hole transport compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and having a conjugated structure with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0339] The reactive group-containing charge transport material having a reactive group and a charge transporting skeleton, the non-reactive charge transport material, and the reactive group-containing non-charge transport material may be selected from known materials.

[0340] The protective layer may also contain other known additives.

[0341] The formation of the protective layer is not particularly limited, and a known formation method can be used. For example, the protective layer can be formed by forming a coating film of a coating liquid for forming the protective layer in which the above components are added to a solvent, drying the coating film, and, if necessary, subjecting it to a curing treatment such as heating.

[0342] Examples of solvents for preparing the coating liquid for forming the protective layer include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as tetrahydrofuran and dioxane, cellosolve solvents such as ethylene glycol monomethyl ether, and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination. The coating liquid for forming the protective layer may be a solvent-free coating liquid.

[0343] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (e.g., a charge transport layer) include conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0344] The thickness of the protective layer is set, for example, preferably in the range of 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less.

[0345] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member, a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and a transfer unit that transfers the toner image to the surface of a recording medium. The electrophotographic photosensitive member according to the present embodiment is used as the electrophotographic photosensitive member.

[0346] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus equipped with a fixing means for fixing a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type for directly transferring a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type for primarily transferring a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member, and then secondarily transferring the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of an electrophotographic photosensitive member after transfer of a toner image but before charging; an apparatus equipped with a charge eliminating means for irradiating the surface of an electrophotographic photosensitive member with charge eliminating light for charge elimination after transfer of a toner image but before charging; and an apparatus equipped with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0347] In the case of an intermediate transfer type device, the transfer means may be configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0348] The image forming apparatus according to this embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0349] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include, for example, at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transfer unit.

[0350] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. The main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0351] FIG. 3 is a schematic diagram showing an example of the configuration of an image forming apparatus according to this embodiment. As shown in FIG. 3 , the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming means), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the electrophotographic photosensitive member 7 through the opening of the process cartridge 300, and the transfer device 40 is disposed at a position facing the electrophotographic photosensitive member 7 via the intermediate transfer member 50, with a portion of the intermediate transfer member 50 being in contact with the electrophotographic photosensitive member 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred onto the intermediate transfer member 50 onto a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer means.

[0352] 3 integrally supports an electrophotographic photosensitive member 7, a charging device 8 (an example of a charging means), a developing device 11 (an example of a developing means), and a cleaning device 13 (an example of a cleaning means) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photosensitive member 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0353] FIG. 3 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists cleaning, which may be arranged as needed.

[0354] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0355] -Charging device- The charging device 8 may be, for example, a contact-type charger using a conductive or semi-conductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also usable are non-contact type roller chargers, scorotron chargers and corotron chargers that utilize corona discharge, and other known chargers.

[0356] -Exposure equipment- The exposure device 9 may be, for example, an optical system that exposes the surface of the electrophotographic photosensitive member 7 to light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photosensitive member. The wavelength of semiconductor lasers is mainly near-infrared, with an oscillation wavelength around 780 nm. However, this wavelength is not limited to this, and lasers with an oscillation wavelength in the 600 nm range or blue lasers with an oscillation wavelength of 400 nm to 450 nm may also be used. Furthermore, for color image formation, a surface-emitting laser light source capable of outputting multiple beams is also effective.

[0357] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contact or non-contact application of a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected depending on the purpose. For example, it may be a known developing device that has a function of applying a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, roller, or the like. Among these, a developing roller that holds a developer on its surface is preferred.

[0358] The developer used in the developing device 11 may be a one-component developer containing only toner, or a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Known developers are used.

[0359] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning type or a simultaneous development cleaning type may also be used.

[0360] -Transfer device- Examples of the transfer device 40 include a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a known transfer charger such as a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0361] -Intermediate transfer body- A belt-like intermediate transfer belt containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. is used as the intermediate transfer body 50. The intermediate transfer body may be in the form of a drum other than a belt.

[0362] FIG. 4 is a schematic diagram showing another example of the configuration of the image forming apparatus according to the present embodiment. The image forming apparatus 120 shown in Fig. 4 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used per color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem-type apparatus. [Example]

[0363] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples in any way. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, syntheses, treatments, manufacturing, etc. were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0364] <Preparing polyester resin> Polyester resins (PE1) to (PE7) were prepared. Tables 2 to 4 show the units and compositions of the polyester resins. The "structural unit: composition ratio" (for example, A2-3:50) is shown in Tables 2 to 4. The composition ratio is the mol % of the dicarboxylic acid unit and the diol unit, respectively. A2-3 and the like shown in Tables 2 to 4 are specific examples of the dicarboxylic acid unit (A) already described. B1-4 and the like shown in Tables 2 to 4 are specific examples of the diol unit (B) already described.

[0365] <Preparing polycarbonate resin> Polycarbonate resins (PC1) to (PC5) were prepared. Table 3 shows the units and compositions that make up the polycarbonate resins. Table 3 shows the "structural unit: composition ratio" (for example, Ca2-3:25). The composition ratio is the mol% of each structural unit. Ca2-3 and the like shown in Table 3 are specific examples of the aforementioned structural unit (C).

[0366] <Production of a photoreceptor having a laminated photosensitive layer> [Example S1] - Formation of undercoat layer - As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1.6 mm was prepared.

[0367] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 100 parts of a silane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0368] 110 parts of the surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran and stirred, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring for 5 hours at 50° C. Thereafter, the solid content was filtered off under reduced pressure and dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin added thereto.

[0369] A solution of 60 parts alizarin-modified zinc oxide, 13.5 parts curing agent (blocked isocyanate, trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts butyral resin (trade name: S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) dissolved in 68 parts methyl ethyl ketone was mixed with 5 parts methyl ethyl ketone and dispersed for 2 hours in a sand mill using 1 mm diameter glass beads to obtain a dispersion. To the dispersion, 0.005 parts dioctyltin dilaurate as a catalyst and 4 parts silicone resin particles (trade name: Tospearl 145, manufactured by Momentive Performance Materials Co., Ltd.) were added to obtain a coating solution for forming an undercoat layer. The coating solution for forming the undercoat layer was applied to the outer surface of a conductive substrate by dip coating and dried and cured at 170°C for 40 minutes to form an undercoat layer. The average thickness of the undercoat layer was 25 μm.

[0370] - Formation of charge generation layer - A mixture of 15 parts of hydroxygallium phthalocyanine (charge-generating material) (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using CuKα characteristic X-rays), 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using 1 mm diameter glass beads for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge-generating layer. The coating solution for forming the charge-generating layer was dip-coated onto the undercoat layer and dried at room temperature (25°C±3°C) to form a charge-generating layer with an average thickness of 0.18 μm.

[0371] - Formation of charge transport layer - A coating solution for forming a charge transport layer was obtained by dissolving 60 parts of polyester resin (PE1) as a binder resin, 40 parts of CTM-1 as a charge transport material, and 1.0 part of dimethyl terephthalate as compound (1) in 550 parts of tetrahydrofuran and 50 parts of toluene. The coating solution for forming a charge transport layer was dip-coated onto the charge generation layer and dried at 150°C for 60 minutes to form a charge transport layer with an average thickness of 40 μm.

[0372] [ka]

[0373] [Examples S2 to S28, Comparative Examples SC1 to SC5] Each photoreceptor was prepared in the same manner as in Example S1, except that in forming the charge transport layer, the type of polyester resin or polycarbonate resin, the type of charge transport material, and the type and amount of compound (1) were changed to the specifications shown in Tables 2 and 3. Charge transport materials CTM-2 to CTM-5 are the following compounds.

[0374] [ka]

[0375] <Production of a photoreceptor having a single-layer photosensitive layer> [Example T1] - Formation of a single-layer photosensitive layer - 45.75 parts of polyester resin (PE1) as a binder resin, 1.25 parts of V-type hydroxygallium phthalocyanine as a charge generating material (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in an X-ray diffraction spectrum using Cukα characteristic X-rays) as a charge generating material, 9 parts of ETM-1 as an electron transport material, 44 parts of CTM-1 as a charge transport material, 2.0 parts of dimethyl terephthalate as compound (1), and 175 parts of tetrahydrofuran and 75 parts of toluene as solvents were mixed, and the mixture was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours to obtain a coating solution for forming a single-layer photosensitive layer. The obtained coating solution for forming a photosensitive layer was applied onto an aluminum substrate having an outer diameter of 30 mm, a length of 365 mm, and a thickness of 1.6 mm by a dip coating method, and dried at a temperature of 150°C for 60 minutes to form a single-layer photosensitive layer with an average thickness of 36 μm.

[0376] [ka]

[0377] [Examples T2 to T19, Comparative Examples TC1 to TC3] Each photoreceptor was prepared in the same manner as in Example T1, except that in forming the single-layer photosensitive layer, the type of polyester resin and the type and amount of compound (1) were changed to the specifications shown in Table 4.

[0378] <Photoreceptor performance evaluation> [Electrical characteristics] The photoreceptor was mounted in an electrophotographic image forming apparatus (Apeos C7070, manufactured by Fujifilm Business Innovation Co., Ltd.). A 30% halftone black image was printed on A3-sized plain paper in two environments: a low-temperature, low-humidity environment (temperature 10°C, relative humidity 15%), and a high-temperature, high-humidity environment (temperature 28°C, relative humidity 85%). The residual potential of the photoreceptor after printing was measured. The difference in absolute values ​​of the two residual potentials was calculated and classified as follows. The results are shown in Tables 2 to 4. A: The difference is less than 15V B: The difference is 15V or more and less than 30V C: Difference is 30V or more

[0379] [Wear resistance] The photoreceptor was mounted in the image forming apparatus described above. In a low-temperature, low-humidity environment with a temperature of 10°C and a relative humidity of 15%, 20,000 copies of each of 100% solid images in yellow, magenta, cyan, and black were printed on A3-sized paper, for a total of 80,000 copies. The average thickness (nm) of the charge transport layer (or single-layer photosensitive layer) was determined before and after this image formation, and the difference in average thickness before and after image formation was recorded as the amount of wear (nm). A Permascope manufactured by Fischerscope was used to measure the film thickness. The amount of wear was classified as follows. The results are shown in Tables 2 to 4. A: Abrasion volume less than 1000nm B: Abrasion amount is 1000nm or more and less than 1500nm C: Abrasion amount is 1500nm or more and less than 2000nm D: Abrasion amount is 2000nm or more and less than 2500nm E: Abrasion amount is 2500nm or more

[0380] [Table 2]

[0381] [Table 3]

[0382] [Table 4] [Explanation of symbols]

[0383] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0384] 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming apparatus, 120 image forming apparatus, 131 cleaning blade, 132 fibrous member (roll-shaped), 133 fibrous member (flat brush-shaped), 300 process cartridge

Claims

1. a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the conductive substrate; the charge transport layer contains a charge transport material, a polyester resin having a structural unit with an aromatic ring, and dimethyl terephthalate; Electrophotographic photoreceptor.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the mass ratio of the dimethyl terephthalate to the total mass of the charge transport layer is 0.1 mass % or more and less than 7.0 mass %.

3. A conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer contains a charge transport material, a polyester resin having a structural unit with an aromatic ring, and dimethyl terephthalate; Electrophotographic photoreceptor.

4. The electrophotographic photoreceptor according to claim 3 , wherein a mass ratio of the dimethyl terephthalate to the total mass of the single-layer photosensitive layer is 0.2 mass % or more and less than 14.0 mass %.

5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the polyester resin having a structural unit having an aromatic ring comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B): 【Chemistry 1】 In formula (A), Ar Ａ１ and Ar Ａ２ each independently represents an aromatic ring which may have a substituent, and L Ａ is a single bond or a divalent linking group, n Ａ１ is 0, 1 or 2. In formula (B), Ar Ｂ１ and Ar Ｂ２ each independently represents an aromatic ring which may have a substituent, and L Ｂ is a single bond, an oxygen atom, a sulfur atom, or -C(Rb １ )(Rb ２ )- and n Ｂ１ is 0, 1 or 2. １ and Rb ２ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb １ and Rb ２ may be bonded to form a cyclic alkyl group.

6. 6. The electrophotographic photoreceptor according to claim 5, wherein the dicarboxylic acid unit (A) represented by formula (A) comprises at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1) below, a dicarboxylic acid unit (A2) represented by formula (A2) below, a dicarboxylic acid unit (A3) represented by formula (A3) below, and a dicarboxylic acid unit (A4) represented by formula (A4) below. 【Chemistry 2】 In formula (A1), n １０１ is an integer of 0 to 4, １０１ Ra １０１ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A2), n ２０１ and n ２０２ are each independently an integer of 0 to 4, ２０１ Ra ２０１ and n ２０２ Ra ２０２ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

7. 7. The electrophotographic photoreceptor according to claim 5, wherein the diol unit (B) represented by formula (B) comprises at least one selected from the group consisting of a diol unit (B1) represented by formula (B1): 【Transformation 3】 【Chemistry 4】 In formula (B1), Rb １０１ is a branched alkyl group having 4 to 20 carbon atoms, and Rb ２０１ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０１ , Rb ５０１ , Rb ８０１ and Rb ９０１ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B2), Rb １０２ is a linear alkyl group having 4 to 20 carbon atoms, and Rb ２０２ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０２ , Rb ５０２ , Rb ８０２ and Rb ９０２ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B3), Rb １１３ and Rb ２１３ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb ４０３ , Rb ５０３ , Rb ８０３ and Rb ９０３ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B4), Rb １０４ and Rb ２０４ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０４ , Rb ５０４ , Rb ８０４ and Rb ９０４ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B5), Ar １０５ is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb ２０５ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０５ , Rb ５０５ , Rb ８０５ and Rb ９０５ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B6), Rb １１６ and Rb ２１６ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb ４０６ , Rb ５０６ , Rb ８０６ and Rb ９０６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B7), Rb ４０７ , Rb ５０７ , Rb ８０７ and Rb ９０７ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B8), Rb ４０８ , Rb ５０８ , Rb ８０８ and Rb ９０８ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

8. An electrophotographic photosensitive member described in any one of claims 5 to 7, wherein the diol unit (B) represented by the formula (B) includes a diol unit (B1) represented by the following formula (B1): 【Transformation 5】 In formula (B1), Rb １０１ is a branched alkyl group having 4 to 20 carbon atoms, and Rb ２０１ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０１ , Rb ５０１ , Rb ８０１ and Rb ９０１ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

9. a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the conductive substrate; the charge transport layer contains a charge transport material, a polyester resin having a structural unit with an aromatic ring, and a compound (1) represented by the following formula (1) and having a melting point of 40° C. or higher, The polyester resin having a structural unit having an aromatic ring comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B), and the diol unit (B) represented by the formula (B) comprises a diol unit (B1) represented by the following formula (B1): Electrophotographic photoreceptor. 【Transformation 6】 In formula (1), Ar is an aromatic ring which may have a substituent; L is a single bond, an oxygen atom, or a sulfur atom; R is an alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an aralkyl group having from 7 to 20 carbon atoms; and n is an integer of 1 or greater. 【Transformation 7】 In formula (A), Ar Ａ１ and Ar Ａ２ each independently represents an aromatic ring which may have a substituent, and L Ａ is a single bond or a divalent linking group, n Ａ１ is 0, 1 or 2. In formula (B), Ar Ｂ１ and Ar Ｂ２ each independently represents an aromatic ring which may have a substituent, and L Ｂ is a single bond, an oxygen atom, a sulfur atom, or -C(Rb １ )(Rb ２ )- and n Ｂ１ is 0, 1 or 2. １ and Rb ２ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb １ and Rb ２ may be bonded to form a cyclic alkyl group. 【Transformation 8】 In formula (B1), Rb １０１ is a branched alkyl group having 4 to 20 carbon atoms, and Rb ２０１ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０１ , Rb ５０１ , Rb ８０１ and Rb ９０１ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

10. The electrophotographic photoreceptor according to claim 9 , wherein the mass ratio of the compound (1) to the total mass of the charge transport layer is 0.1 mass % or more and less than 7.0 mass %.

11. 11. The electrophotographic photoreceptor according to claim 9 or 10, wherein the compound (1) comprises a compound represented by formula (1) in which Ar is an aromatic ring having 6 carbon atoms, L is a single bond, R is a methyl group, and n is an integer of 1 or more.

12. The electrophotographic photoreceptor according to any one of claims 9 to 11, wherein the dicarboxylic acid unit (A) represented by formula (A) comprises at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1) below, a dicarboxylic acid unit (A2) represented by formula (A2) below, a dicarboxylic acid unit (A3) represented by formula (A3) below, and a dicarboxylic acid unit (A4) represented by formula (A4) below: 【Chemistry 9】 In formula (A1), n １０１ is an integer of 0 to 4, １０１ Ra １０１ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A2), n ２０１ and n ２０２ are each independently an integer of 0 to 4, ２０１ Ra ２０１ and n ２０２ Ra ２０２ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

13. The electrophotographic photoreceptor according to any one of claims 1 to 12, wherein the charge transport material comprises at least one selected from the group consisting of a compound (D1) represented by the following formula (D1), a compound (D2) represented by the following formula (D2), a compound (D3) represented by the following formula (D3), and a compound (D4) represented by the following formula (D4): 【Chemistry 10】 In formula (D1), Ar Ｔ１ , Ar Ｔ２ and Ar Ｔ３ each independently represents an aryl group, —C ６ H ４ -C(R Ｔ４ ) = C(R Ｔ５ )(R Ｔ６ ) or -C ６ H ４ -CH=CH-CH=C(R Ｔ７ )(R Ｔ８ ) is. R Ｔ４ , R Ｔ５ , R Ｔ６ , R Ｔ７ and R Ｔ８ are each independently a hydrogen atom, an alkyl group, or an aryl group. Ｔ５ and R Ｔ６ is an aryl group, the aryl groups are connected to each other by -C(R ５１ )(R ５２ )- and / or -C(R ６１ ) = C(R ６２ )-. ５１ , R ５２ , R ６１ and R ６２ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In formula (D2), R Ｔ２０１ , R Ｔ２０２ , R Ｔ２１１ and R Ｔ２１２ each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R Ｔ２１ ) = C(R Ｔ２２ )(R Ｔ２３ ) or -CH=CH-CH=C(R Ｔ２４ )(R Ｔ２５ ) is. R Ｔ２１ , R Ｔ２２ , R Ｔ２３ , R Ｔ２４ and R Ｔ２５ are each independently a hydrogen atom, an alkyl group, or an aryl group. Ｔ２２１ and R Ｔ２２２ are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2. In formula (D3), R Ｔ３０１ , R Ｔ３０２ , R Ｔ３１１ and R Ｔ３１２ each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R Ｔ３１ ) = C(R Ｔ３２ )(R Ｔ３３ ) or -CH=CH-CH=C(R Ｔ３４ )(R Ｔ３５ ) is. R Ｔ３１ , R Ｔ３２ , R Ｔ３３ , R Ｔ３４ and R Ｔ３５ are each independently a hydrogen atom, an alkyl group, or an aryl group. Ｔ３２１ , R Ｔ３２２ and R Ｔ３３１ are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2. In formula (D4), R Ｔ４０１ , R Ｔ４０２ , R Ｔ４１１ and R Ｔ４１２ each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R Ｔ４１ ) = C(R Ｔ４２ )(R Ｔ４３ ) or -CH=CH-CH=C(R Ｔ４４ )(R Ｔ４５ ) is. R Ｔ４１ , R Ｔ４２ , R Ｔ４３ , R Ｔ４４ and R Ｔ４５ are each independently a hydrogen atom, an alkyl group, or an aryl group. Ｔ４２１ , R Ｔ４２２ and R Ｔ４３１ are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 are each independently 0, 1, or 2.

14. An electrophotographic photoreceptor according to any one of claims 1 to 13, A process cartridge that is detachably attached to an image forming apparatus.

15. The electrophotographic photoreceptor according to any one of claims 1 to 13, an electrostatic latent image forming means for forming an electrostatic latent image on the surface of a charged photoreceptor; a developing means for storing a developer containing a toner and developing an electrostatic latent image formed on the surface of the photosensitive member using the developer to form a toner image; a transfer means for transferring the toner image onto a recording medium, Image forming device.

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