Electrophotographic photoreceptor, process cartridge and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in electrification maintainability and has a reduced residual potential.SOLUTION: An electrophotographic photoreceptor comprises: a conductive substrate; an undercoat layer arranged on the conductive substrate; and a photosensitive layer arranged on the undercoat layer. The undercoat layer includes a triarylamine compound having a reactive group, a curing agent, and an electron transport material, and is formed of a cured product of a composition including butyral resin in a content of 0 mass% or more and 5 mass% or less relative to the total solid of the undercoat layer.SELECTED DRAWING: Figure 1

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 in which an intermediate layer and a photosensitive layer are provided in this order on a conductive support, and the intermediate layer contains a polyolefin and a benzimidazole-based compound.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer in this order on a support, in which the intermediate layer contains an electron transport material selected from a naphthalene amidine imide compound, a perylene amidine imide compound, and an imide resin.

[0004] Patent Document 3 discloses an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer in this order on a support, in which the intermediate layer contains an electron transport material selected from a naphthalene amidine imide compound and a perylene amidine imide compound.

[0005] Patent Document 4 discloses a benzimidazole compound as an electron transport material used in the undercoat layer of an electrophotographic photoreceptor.

[0006] Patent Document 5 discloses an electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer, in which the undercoat layer contains metal oxide particles surface-treated with a silane coupling agent, a binder resin, and an organic acid salt of a metal selected from bismuth, zinc, cobalt, iron, nickel, and copper. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-095665 [Patent Document 2] Patent No. 3958154 [Patent Document 3] Patent No. 3958155 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-026067 [Patent Document 5] Japanese Patent Application Laid-Open No. 2014-186296 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventionally, polycyclic electron transport materials with high electron transport properties have been suitable for use in the undercoat layer of electrophotographic photoreceptors. However, the performance required for the undercoat layer requires high charge retention. This charge retention is thought to be due to holes, which are minority carriers in the electron transport material. Therefore, an object of the present disclosure is to provide an electrophotographic photoreceptor that has excellent charge retention and reduced residual potential, compared to an electrophotographic photoreceptor having an undercoat layer containing a butyral resin in an amount of more than 5% by mass relative to the total solid content of the undercoat layer. [Means for solving the problem]

[0009] Specific means for solving the above problems include the following aspects.

[0010] <1> a conductive substrate; an undercoat layer disposed on the conductive substrate; a photosensitive layer disposed on the undercoat layer; Equipped with the undercoat layer is composed of a cured product of a composition that includes a triarylamine compound having a reactive group, a curing agent, and an electron transport material, and the content of a butyral resin relative to the total solid content of the undercoat layer is 0% by mass or more and 5% by mass or less. <2> The triarylamine compound having a reactive group includes a hole transport compound represented by the following general formula (I): <1> The electrophotographic photoreceptor according to claim 1. [ka] (In the general formula (I), R1 , R 2 and R 3 each independently represents a hydrogen atom, a hydroxy group, a hydroxyalkyl group having 1 to 6 carbon atoms, an amino group (NH group), a thiol group, an alkylthiol group, a carboxy group, or a carboxyalkyl group; X 1 , X 2 and X 3 each independently represents a halogen atom, an alkyl group, an alkoxy group, an ester group, an aryl group, an aralkyl group, or a vinylphenyl group.

[0011] <3> In the general formula (I), R 1 , R 2 and R 3 each independently represents a hydroxy group, a hydroxyalkyl group having 1 to 4 carbon atoms, an amino group (NH group), a carboxy group, or a carboxyalkyl group having 1 to 4 carbon atoms; X 1 , X 2 and X 3 each independently represents an alkyl group having 1 to 3 carbon atoms, an aryl group, or a vinylphenyl group, <2> The electrophotographic photoreceptor according to claim 1.

[0012] <4> The electron transport material includes at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), (6), (7), and (8): <1> ~ <3> 10. The electrophotographic photoreceptor according to claim 9, wherein the first and second electrodes are electrically connected to the first and second electrodes. In general formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 11 and R 12, R 12 and R 13 and R 13 and R 14 may each independently be linked to each other to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 may each independently be linked to each other to form a ring. In general formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 21 and R 22 , R 22 and R 23 and R 23 and R 24 may each independently be linked to each other to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 may each independently be linked to each other to form a ring. In general formula (3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47, R 48 , R 49 and R 50 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (6), R 61 , R 62 , R 63 and R 64 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In general formula (8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 , R 87 and R 88 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). [ka]

[0013] <5> the content of the triarylamine compound having a reactive group is 0.1% by mass or more and 10% by mass or less based on the total solid content of the undercoat layer; <1> ~ <4> 10. The electrophotographic photoreceptor according to claim 9, wherein the first and second electrodes are electrically connected to the first and second electrodes. <6> the content of the electron transport material is 50% by mass or more and 80% by mass or less with respect to the total solid content of the undercoat layer; <1> ~ <5> 10. The electrophotographic photoreceptor according to claim 9, wherein the first and second electrodes are electrically connected to the first and second electrodes. <7> The aforementioned <1> ~ <6> The electrophotographic photoreceptor according to any one of the above items is provided, A process cartridge that is detachably attached to an image forming apparatus. <8> The aforementioned <1> ~ <6> an electrophotographic photoreceptor according to any one of the above items; a charging means for charging the surface of the electrophotographic photosensitive member; an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member; a developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing a toner to form a toner image; a transfer means for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: [Effects of the Invention]

[0014] According to the inventions of [1], [2], [3], and [4], there is provided an electrophotographic photoreceptor which has excellent charge retention and reduced residual potential, compared to when the undercoat layer contains more than 5 mass % of a butyral resin based on the total solid content of the undercoat layer. According to the invention related to [5], an electrophotographic photoreceptor is provided which is excellent in charge retention and has reduced residual potential, compared to when the content of the triarylamine compound having a reactive group is less than 0.1 mass % or more than 10 mass % relative to the total solid content of the undercoat layer. According to the invention of [6], an electrophotographic photoreceptor is provided which has excellent charge retention and reduced residual potential, compared to when the content of the charge transport material is less than 50% by mass or more than 80% by mass, based on the total solid content of the undercoat layer. According to the invention of [8], there is provided a process cartridge having an electrophotographic photosensitive member which has excellent charge retention and reduced residual potential compared to a case where an undercoat layer is provided which contains more than 5 mass % of butyral resin relative to the total solid content of the undercoat layer. According to the invention of [9], there is provided an image forming apparatus including an electrophotographic photoreceptor which has excellent charge retention and reduced residual potential compared to an electrophotographic photoreceptor having an undercoat layer containing more than 5 mass % of butyral resin relative to the total solid content of the undercoat layer. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic partial cross-sectional view showing an example of a layer structure of an electrophotographic photosensitive member according to an exemplary embodiment. [Figure 2] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 3] 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

[0016]

[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.

[0017] 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.

[0018] 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. In addition, 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.

[0019] In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0020] 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.

[0021] In the present disclosure, the term "major component" refers to a major component, such as a component that accounts for 30% by mass or more of the total mass of a mixture of multiple components.

[0022] In the present disclosure, the electrophotographic photoreceptor may also be simply referred to as a photoreceptor.

[0023] <Electrophotographic photoreceptor> The photoreceptor according to this embodiment includes a conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer.

[0024] Fig. 1 schematically shows an example of the layer structure of a photoreceptor according to this embodiment. Photoreceptor 7A shown in Fig. 1 has a structure in which an undercoat layer 1, a charge generation layer 2, and a charge transport layer 3 are laminated in this order on a conductive substrate 4. The charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer 5. Photoreceptor 7A may also have a layer structure in which a protective layer is further provided on the charge transport layer 3.

[0025] In the photoreceptor according to this embodiment, the photosensitive layer may be a functionally separated photosensitive layer in which the charge generation layer 2 and the charge transport layer 3 are separated, as in the photoreceptor 7A shown in FIG. 1, or may be a single-layer photosensitive layer having charge generation and charge transport capabilities instead of the charge generation layer 2 and the charge transport layer 3.

[0026] The electrophotographic photoreceptor according to the present embodiment includes a conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer, wherein the undercoat layer is composed of a cured product of a composition that includes a triarylamine compound having a reactive group, a curing agent, and an electron transport material, and the content of a butyral resin relative to the total solid content of the undercoat layer is 0% by mass or more and 5% by mass or less.

[0027] Photoreceptors with an undercoat layer containing an electron transport material have a reduced residual potential. However, conventional photoreceptors with an undercoat layer containing an electron transport material have insufficient charge retention. Although the reason for this is not entirely clear, it is thought that after charging, a small number of holes in the electron transport material contained in the undercoat layer move, causing charge injection into the charge-generating material (e.g., phthalocyanine pigment) contained in the photosensitive layer, resulting in attenuation of the potential on the photoreceptor surface. As a result of our investigations, we have found that when a cured product of a composition constituting an undercoat layer contains a curing agent and a triarylamine compound having a reactive group together with an electron transport material, the charge retention is excellent. The mechanism behind this is believed to be that the triarylamine compound acts as an electron donor to capture holes, which are minority carriers in the electron transport material, thereby effectively preventing their injection into the charge generating material. Furthermore, the reactive group of the triarylamine improves compatibility with the curing agent and butyral resin, thereby reducing unreacted residues in the cured film and making it less susceptible to environmental influences, from high temperature and high humidity to low temperature and low humidity. This is thought to contribute to less decay of the potential on the photoreceptor surface and ensure potential stability.

[0028] In this embodiment, by including a triarylamine compound having a reactive group, the reactive group of the triarylamine compound reacts with the curing agent and polymerizes, resulting in curing while maintaining compatibility, which is thought to result in excellent film-forming properties. It is also presumed that the triarylamine compound acts as an electron donor for holes in the electron transport material, thereby suppressing hole migration from the electron transport material to the charge generation layer.

[0029] Furthermore, by maintaining the butyral resin content at 5% by mass or less relative to the total solid content of the undercoat layer, the unreacted groups in the undercoat layer can be reduced, and the electron transport properties of the electron transport material are not impaired, and the stability of the repeated use characteristics of the photoreceptor, which is less susceptible to environmental fluctuations, is improved.

[0030] As described above, the electrophotographic photoreceptor according to this embodiment has excellent charge retention properties and reduced residual potential.

[0031] Hereinafter, each layer of the electrophotographic photoreceptor according to this embodiment will be described in detail, with reference numerals omitted.

[0032] [Sublayer] -Cured product of composition constituting undercoat layer- The undercoat layer is composed of a cured product of a composition containing a triarylamine compound having a reactive group, a curing agent, and an electron transport material, and the content of butyral resin relative to the total solid content of the undercoat layer is 0% by mass or more and 5% by mass or less. The composition may contain other curing agents, inorganic particles, curing catalysts, additives, etc., other than those in the above group, as necessary.

[0033] -Triarylamine compound having a reactive group- The triarylamine compound having a reactive group refers to a triarylamine compound having a group capable of reacting with at least the isocyanate compound contained in the composition and polymerizing therewith.

[0034] Examples of the reactive group include a hydroxyl group, an amide group, an amino group (NH2 group), a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxy group, and a carboxyalkyl group.

[0035] The triarylamine compound having a reactive group preferably contains a hole transport compound represented by the following general formula (I): When the hole transport compound represented by the following general formula (I) is contained, the triarylamine compound acts by donating electrons to holes in the electron transport material, and the movement of holes to the charge generation layer is further suppressed, resulting in more excellent charge retention.

[0036] [ka]

[0037] In general formula (I), R 1 , R 2 and R 3 (Hereafter, simply "R 1 ~R 3 ") each independently represent a hydrogen atom, a hydroxy group, a hydroxyalkyl group having 1 to 6 carbon atoms, an amino group (NH group), a thiol group, an alkylthiol group, a carboxy group, or a carboxyalkyl group; X 1 , X 2 and X 3 (Hereafter, simply "X 1 ~X 3 ") each independently represent a halogen atom, an alkyl group, an alkoxy group, an ester group, an aryl group, an aralkyl group, or a vinylphenyl group (a styryl group).

[0038] In general formula (I), R 1 ~R 3 Examples of the hydroxyalkyl group having 1 to 6 carbon atoms represented by the formula (I) include a hydroxymethyl group, a hydroxyethyl group, a hydroxybutyl group, a hydroxypropyl group, a hydroxypentyl group, a 2-hydroxypropyl group, etc. Among these, a hydroxyalkyl group having 1 to 5 carbon atoms is preferred, and a hydroxyalkyl group having 1 to 3 carbon atoms is more preferred.

[0039] In general formula (I), R 1 ~R 3The alkylthiol group represented by the formula (-R-SH, where R represents an alkyl chain) is preferably an alkylthiol group having 1 to 10 carbon atoms, more preferably an alkylthiol group having 1 to 5 carbon atoms, and even more preferably an alkylthiol group having 1 to 3 carbon atoms. Examples of the alkylthiol group having 1 to 10 carbon atoms include a methylthiol group, an ethylthiol group, a propylthiol group, a tert-butylthiol group, an octylthiol group, and a nonylthiol group.

[0040] In general formula (I), R 1 ~R 3 The carboxyalkyl group represented by the formula (I) is preferably a carboxyalkyl group having 2 to 10 carbon atoms, more preferably a carboxyalkyl group having 2 to 6 carbon atoms, and even more preferably a carboxyalkyl group having 2 to 4 carbon atoms. Examples of the carboxyalkyl group having from 2 to 10 carbon atoms include a 2-carboxyethyl group, a 3-carboxypropyl group, a 4-carboxybutyl group, and a carboxymethyl group.

[0041] In general formula (I), X 1 ~X 3 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a bromine atom, and an iodine atom.

[0042] In general formula (I), X 1 ~X 3 Examples of the alkyl group represented by the formula (I) include a linear alkyl group having 1 to 10 carbon atoms (preferably 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms), a branched alkyl group having 3 to 10 carbon atoms (preferably 3 to 6 carbon atoms), and a cyclic alkyl group having 3 to 10 carbon atoms (preferably 3 to 6 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 the branched alkyl group 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, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0043] In general formula (I), X 1 ~X 3 Examples of the alkoxy group represented by the formula include linear, branched, and cyclic alkoxy groups having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4). Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group. Specific examples of branched alkoxy groups 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, a tert-hexyloxy group, an isoheptyloxy group, a sec-heptyloxy group, a tert-heptyloxy group, an isooctyloxy group, a sec-octyloxy group, a tert-octyloxy group, an isononyloxy group, a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, and a tert-decyloxy group. Specific examples of the cyclic alkoxy group include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group, a cyclononyloxy group, and a cyclodecyloxy group.

[0044] In general formula (I), X 1 ~X 3 The aryl group represented by the formula (I) is preferably an aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. 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, a 9-anthryl group, a 9-phenanthryl group, a 1-pyrenyl group, a 5-naphthacenyl group, a 1-indenyl group, a 2-azulenyl group, a 9-fluorenyl group, a biphenylenyl group, an indacenyl group, a fluoranthenyl group, an acenaphthylenyl group, an aceanthryllenyl group, a phenalenyl group, a fluorenyl group, and an anthryl group.

[0045] In general formula (I), X 1 ~X 3 The aralkyl group represented by the formula (I) is preferably an aralkyl group having 7 to 20 carbon atoms, more preferably an aralkyl group having 7 to 15 carbon atoms, and even more preferably an aralkyl group having 7 to 10 carbon atoms.

[0046] Examples of the unsubstituted aralkyl group having from 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.

[0047] In one embodiment, the hole transport compound represented by general formula (I) is a compound represented by general formula (I) 1 , R 2 and R 3 each independently represents a hydrogen atom, a hydroxy group, a hydroxyalkyl group having 1 to 4 carbon atoms, an amino group (NH group), a carboxy group, or a carboxyalkyl group having 1 to 4 carbon atoms; X 1 , X 2 and X 3Preferably, each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, or a vinylphenyl group (styryl group). 1 ~R 3 and X 1 ~X 3 is the above group, when the composition is cured, the triarylamine compound having a reactive group is likely to react with an isocyanate compound, etc., contained in the composition. As a result, the undercoat layer has excellent film-forming properties and is further suppressed in hole migration, resulting in excellent charge retention.

[0048] Exemplary compounds of the hole transport compound represented by general formula (I) are shown below, but the invention is not limited to these.

[0049] [ka]

[0050] The content of the triarylamine compound having a reactive group is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, and even more preferably 2% by mass or more and 5% by mass or less, based on the total solid content of the undercoat layer. When the content of the triarylamine compound having a reactive group relative to the total solid content of the undercoat layer is 0.1% by mass or more, the charge retention is superior. When the content is 10% by mass or less, unreacted triarylamine compound having a reactive group remains in the cured film, which prevents coating defects due to crystal precipitation in the film, and the charge retention is superior.

[0051] -Electron transport material- Examples of electron transport materials include electron transporting compounds such as perinone compounds, naphthalenetetracarboxylic diimide compounds, perylenetetracarboxylic diimide compounds, quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, dinaphthoquinone compounds, diphenoquinone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, and ethylene compounds. One type of electron transport material may be used alone, or two or more types may be used in combination.

[0052] The electron transport material preferably comprises at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), (6), (7), and (8), more preferably at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (7), and (8), still more preferably at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1), (2), and (7), and particularly preferably at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1) and (2).

[0053] The electron transport materials represented by the following general formulas (1), (2), (3), (4), (5), (6), (7), and (8) (more preferably the compounds represented by general formulas (1) and (2)) have excellent dispersion stability in mixtures with curing agents, isocyanate compounds, and solvents (particularly solvents such as esters and ketones), and tend to improve the film-forming properties of the undercoat layer. Therefore, when at least one electron transport material selected from the group consisting of these compounds is included, the electron transport material is easily dispersed in the undercoat layer, enabling uniform electron transport within the film, and the excellent electron transport properties are thought to further suppress the residual potential.

[0054] [ka]

[0055] In general formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 11 and R 12 , R 12 and R 13 and R 13 and R 14 may each independently be linked to each other to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 may each independently be linked to each other to form a ring. In general formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 21 and R 22 , R 22 and R 23 and R 23 and R 24 may each independently be linked to each other to form a ring. 25 and R 26 , R26 and R 27 and R 27 and R 28 may each independently be linked to each other to form a ring. In general formula (3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (6), R 61 , R 62 , R 63 and R 64 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In general formula (8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 , R 87 and R 88 each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0056] <Compounds represented by general formula (1) and general formula (2)> The compounds represented by general formula (1) and general formula (2) will be explained below.

[0057] [ka]

[0058] In general formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 (Hereafter, simply "R 11 ~R 18 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. R 11 and R 12 , R 12 and R 13 and R 13 and R 14 may each independently be linked to each other to form a ring.15 and R 16 , R 16 and R 17 and R 17 and R 18 may each independently be linked to each other to form a ring.

[0059] In general formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 (Hereafter, simply "R 21 ~R 28 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. R 21 and R 22 , R 22 and R 23 and R 23 and R 24 may each independently be linked to each other to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 may each independently be linked to each other to form a ring.

[0060] In general formula (1), R 11 ~R 18 The alkyl group represented by the formula (I) may be a substituted or unsubstituted alkyl group.

[0061] In general formula (1), R 11 ~R 18Examples of the unsubstituted alkyl group represented by the formula (I) include a linear alkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and a cyclic alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0062] Examples of the linear alkyl group having 1 to 20 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, 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.

[0063] Examples of the branched alkyl group having 3 to 20 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, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0064] Examples of the cyclic alkyl group having 3 to 20 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.

[0065] Among the above, the unsubstituted alkyl group is preferably a straight-chain alkyl group such as a methyl group or an ethyl group.

[0066] Substituents in the alkyl group include an alkoxy group, a hydroxy group, a carboxy group, a nitro group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkoxy group that substitutes the hydrogen atom in the alkyl group is R 11 ~R 18 Examples of the alkoxy group include the same groups as the unsubstituted alkoxy group represented by the following formula:

[0067] In general formula (1), R 11 ~R 18 The alkoxy group represented by the formula (I) includes a substituted or unsubstituted alkoxy group.

[0068] In general formula (1), R 11 ~R 18 Examples of the unsubstituted alkoxy group represented by the formula include linear, branched or cyclic alkoxy groups having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4).

[0069] Specific examples of the linear alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group. Specific examples of branched alkoxy groups 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, a tert-hexyloxy group, an isoheptyloxy group, a sec-heptyloxy group, a tert-heptyloxy group, an isooctyloxy group, a sec-octyloxy group, a tert-octyloxy group, an isononyloxy group, a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, and a tert-decyloxy group. Specific examples of the cyclic alkoxy group include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group, a cyclononyloxy group, and a cyclodecyloxy group. Among these, the unsubstituted alkoxy group is preferably a linear alkoxy group.

[0070] Substituents in the alkoxy group include an aryl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a hydroxyl group, a carboxy group, a nitro group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The aryl group that substitutes the hydrogen atom in the alkoxy group is, for example, R 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula: The alkoxycarbonyl group that substitutes the hydrogen atom in the alkoxy group is, for example, R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that substitutes the hydrogen atom in the alkoxy group is, for example, R 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0071] In general formula (1), R 11 ~R 18 The aralkyl group represented by the formula (I) includes a substituted or unsubstituted aralkyl group.

[0072] In general formula (1), R 11 ~R 18 The unsubstituted aralkyl group represented by the formula (I) is preferably an aralkyl group having 7 to 30 carbon atoms, more preferably an aralkyl group having 7 to 16 carbon atoms, and even more preferably an aralkyl group having 7 to 12 carbon atoms.

[0073] Examples of the unsubstituted aralkyl group having from 7 to 30 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.

[0074] Substituents in the aralkyl group include an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkoxy group that substitutes the hydrogen atom in the aralkyl group includes, for example, R 11 ~R 18 Examples of the alkoxy group include the same groups as the unsubstituted alkoxy group represented by the following formula: The alkoxycarbonyl group that substitutes the hydrogen atom in the aralkyl group includes, for example, R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that substitutes the hydrogen atom in the aralkyl group includes, for example, R 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0075] In general formula (1), R 11 ~R 18 The aryl group represented by the formula (I) includes a substituted or unsubstituted aryl group.

[0076] In general formula (1), R 11 ~R 18 The unsubstituted aryl group represented by the formula (I) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms.

[0077] Examples of the aryl group having 6 to 30 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, a 2-naphthyl group, a 9-anthryl group, a 9-phenanthryl group, a 1-pyrenyl group, a 5-naphthacenyl group, a 1-indenyl group, a 2-azulenyl group, a 9-fluorenyl group, a biphenylenyl group, an indacenyl group, a fluoranthenyl group, an acenaphthylenyl group, an aceanthryllenyl group, a phenalenyl group, and a fluorenyl group. Examples of such groups include anthryl, bianthracenyl, teranthracenyl, quaternanthracenyl, anthraquinolyl, phenanthryl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, pleiadenyl, picenyl, perylenyl, pentaphenyl, pentacenyl, tetraphenylenyl, hexaphenyl, hexacenyl, rubicenyl, and coronenyl. Of these, phenyl is preferred.

[0078] Substituents in the aryl group include an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkyl group that substitutes the hydrogen atom in the aryl group is, for example, R 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula: The alkoxy group that substitutes the hydrogen atom in the aryl group is, for example, R 11 ~R 18 Examples of the alkoxy group include the same groups as the unsubstituted alkoxy group represented by the following formula: The alkoxycarbonyl group that substitutes the hydrogen atom in the aryl group is, for example, R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that substitutes the hydrogen atom in the aryl group is, for example, R 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0079] In general formula (1), R11 ~R 18 The aryloxy group represented by the formula (-O-Ar, where Ar represents an aryl group) includes a substituted or unsubstituted aryloxy group.

[0080] In general formula (1), R 11 ~R 18 The unsubstituted aryloxy group represented by the formula (I) is preferably an aryloxy group having 6 to 30 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, and even more preferably an aryloxy group having 6 to 10 carbon atoms.

[0081] Examples of the aryloxy group having 6 to 30 carbon atoms include a phenyloxy group (phenoxy group), a biphenyloxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 9-anthryloxy group, a 9-phenanthryloxy group, a 1-pyrenyloxy group, a 5-naphthacenyloxy group, a 1-indenyloxy group, a 2-azulenyloxy group, a 9-fluorenyloxy group, a biphenylenyloxy group, an indacenyloxy group, a fluoranthenyloxy group, an acenaphthylenyloxy group, an aceanthryloxy group, a phenalenyloxy group, and a fluorenyloxy group. Examples of the alkyl group include a phenyloxy group, an anthryloxy group, a bianthracenyloxy group, a tert-anthracenyloxy group, a quaternary anthracenyloxy group, an anthraquinolyloxy group, a phenanthryloxy group, a triphenylenyloxy group, a pyrenyloxy group, a chrysenyloxy group, a naphthacenyloxy group, a pleiadenyloxy group, a picenyloxy group, a perylenyloxy group, a pentaphenyloxy group, a pentacenyloxy group, a tetraphenylenyloxy group, a hexaphenyloxy group, a hexacenyloxy group, a rubicenyloxy group, and a coronenyloxy group. Among the above, a phenyloxy group (phenoxy group) is preferred.

[0082] Substituents in the aryloxy group include an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkyl group that substitutes the hydrogen atom in the aryloxy group is, for example, R 11~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula: The alkoxycarbonyl group that substitutes the hydrogen atom in the aryloxy group is, for example, R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that substitutes the hydrogen atom in the aryloxy group is, for example, R 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0083] In general formula (1), R 11 ~R 18 The alkoxycarbonyl group represented by the formula (-CO-OR, where R represents an alkyl group) includes a substituted or unsubstituted alkoxycarbonyl group.

[0084] In general formula (1), R 11 ~R 18 The number of carbon atoms in the alkyl chain of the unsubstituted alkoxycarbonyl group represented by the following formula is preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less, and even more preferably 1 or more and 10 or less.

[0085] Examples of the alkoxycarbonyl group having an alkyl chain carbon number of 1 to 20 include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, an n-butoxycarbonyl group, a sec-butoxybutylcarbonyl group, a tert-butoxycarbonyl group, a pentaoxycarbonyl group, a hexaoxycarbonyl group, a heptoxycarbonyl group, an octaoxycarbonyl group, a nonaoxycarbonyl group, a decaoxycarbonyl group, a dodecaoxycarbonyl group, a tridecaoxycarbonyl group, a tetradecaoxycarbonyl group, a pentadecaoxycarbonyl group, a hexadecaoxycarbonyl group, a heptadecaoxycarbonyl group, an octadecaoxycarbonyl group, a nonadecaoxycarbonyl group, and an icosaoxycarbonyl group.

[0086] Substituents in the alkoxycarbonyl group include an aryl group, a hydroxy group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The aryl group that substitutes the hydrogen atom in the alkoxycarbonyl group is, for example, R 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula:

[0087] In general formula (1), R 11 ~R 18 The aryloxycarbonyl group represented by the formula (-CO-OAr, where Ar represents an aryl group) includes a substituted or unsubstituted aryloxycarbonyl group.

[0088] In general formula (1), R 11 ~R 18 The number of carbon atoms in the aryl group in the unsubstituted aryloxycarbonyl group represented by the following formula is preferably 6 or more and 30 or less, more preferably 6 or more and 14 or less, and even more preferably 6 or more and 10 or less.

[0089] Examples of aryloxycarbonyl groups having an aryl group having 6 to 30 carbon atoms include a phenoxycarbonyl group, a biphenyloxycarbonyl group, a 1-naphthyloxycarbonyl group, a 2-naphthyloxycarbonyl group, a 9-anthryloxycarbonyl group, a 9-phenanthryloxycarbonyl group, a 1-pyrenyloxycarbonyl group, a 5-naphthacenyloxycarbonyl group, a 1-indenyloxycarbonyl group, a 2-azulenyloxycarbonyl group, a 9-fluorenyloxycarbonyl group, a biphenylenyloxycarbonyl group, an indacenyloxycarbonyl group, a fluoranthenyloxycarbonyl group, an acenaphthylenyloxycarbonyl group, an aceanthryloxycarbonyl group, a phenalenyloxycarbonyl group, and a fluorenyloxycarbonyl group. Examples of the alkyl group include anthryloxycarbonyl, bianthracenyloxycarbonyl, teranthracenyloxycarbonyl, quaternanthracenyloxycarbonyl, anthraquinolyloxycarbonyl, phenanthryloxycarbonyl, triphenylenyloxycarbonyl, pyrenyloxycarbonyl, chrysenyloxycarbonyl, naphthacenyloxycarbonyl, pleiadenyloxycarbonyl, picenyloxycarbonyl, perylenyloxycarbonyl, pentaphenyloxycarbonyl, pentacenyloxycarbonyl, tetraphenylenyloxycarbonyl, hexaphenyloxycarbonyl, hexacenyloxycarbonyl, rubicenyloxycarbonyl, and coronenyloxycarbonyl. Of these, the phenoxycarbonyl group is preferred.

[0090] Substituents in the aryloxycarbonyl group include an alkyl group, a hydroxy group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkyl group that substitutes the hydrogen atom of the aryloxycarbonyl group is, in general formula (1), R 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula:

[0091] In general formula (1), R 11 ~R 18An alkoxycarbonyl alkyl group represented by (-(C n H 2n )-CO-OR, where R represents an alkyl group and n represents an integer of 1 or more. ) includes a substituted or unsubstituted alkoxycarbonylalkyl group.

[0092] In general formula (1), R 11 ~R 18 The alkoxycarbonyl group (—CO—OR) in the unsubstituted alkoxycarbonylalkyl group represented by the general formula (1) is 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the alkoxycarbonyl group represented by the following formula:

[0093] In general formula (1), R 11 ~R 18 The alkylene chain (-C n H 2n -) includes a linear alkylene chain having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkylene chain having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and a cyclic alkylene chain having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0094] Examples of the linear alkylene chain having 1 to 20 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-undecylene group, an n-dodecylene group, a tridecylene group, an n-tetradecylene group, an n-pentadecylene group, an n-heptadecylene group, an n-octadecylene group, an n-nonadecylene group, and an n-icosylene group.

[0095] Examples of the branched alkylene chain having 3 to 20 carbon atoms include an isopropylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an isopentylene group, a neopentylene group, a tert-pentylene group, an isohexylene group, a sec-hexylene group, a tert-hexylene group, an isoheptylene group, a sec-heptylene group, a tert-heptylene group, an isooctylene group, a sec-octylene group, a tert-octylene group, an isonylene group, a sec-nonylene group, a tert-nonylene group, an isodecylene group, a sec-decylene group, a tert-decylene group, an isododecylene group, a sec-dodecylene group, a tert-dodecylene group, a tert-tetradecylene group, and a tert-pentadecylene group.

[0096] Examples of the cyclic alkylene chain having 3 to 20 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, and a cyclodecylene group.

[0097] Substituents in the alkoxycarbonylalkyl group include an aryl group, a hydroxy group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The aryl group that substitutes the hydrogen atom of the alkoxycarbonylalkyl group is, in general formula (1), R 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula:

[0098] In general formula (1), R 11 ~R 18 An aryloxycarbonyl alkyl group represented by (-(C n H 2n ) —CO—OAr, Ar represents an aryl group, and n represents an integer of 1 or more. ) includes a substituted or unsubstituted aryloxycarbonylalkyl group.

[0099] In general formula (1), R 11 ~R 18The aryloxycarbonyl group (—CO—OAr, Ar represents an aryl group) in the unsubstituted aryloxycarbonylalkyl group represented by the general formula (1) is 11 ~R 18 Examples of the aryloxycarbonyl group include the same groups as the aryloxycarbonyl group represented by the following formula:

[0100] In general formula (1), R 11 ~R 18 The alkylene chain (-C n H 2n -) is R in the general formula (1). 11 ~R 18 Examples include the same alkylene chain as in the alkoxycarbonylalkyl group represented by the following formula:

[0101] Substituents in the aryloxycarbonylalkyl group include an alkyl group, a hydroxy group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkyl group that substitutes the hydrogen atom of the aryloxycarbonylalkyl group is, for example, R 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula:

[0102] In general formula (1), R 11 ~R 18 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0103] In general formula (1), R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 or R 17 and R 18However, examples of the ring structure formed by linking together include a benzene ring and a fused ring having 10 to 18 carbon atoms (such as a naphthalene ring, an anthracene ring, a phenanthrene ring, a chrysene ring (benzo[α]phenanthrene ring), a tetracene ring, a tetraphene ring (benzo[α]anthracene ring), and a triphenylene ring). Among these, a benzene ring is preferred as the ring structure formed.

[0104] In general formula (2), R 21 ~R 28 In general formula (1), R 11 ~R 18 Examples of the alkyl group include the same groups as those represented by the following alkyl groups: In general formula (2), R 21 ~R 28 The alkoxy group represented by the formula (1) includes R 11 ~R 18 Examples of the alkoxy group include the same groups as the alkoxy group represented by the following formula: In general formula (2), R 21 ~R 28 As the aralkyl group represented by the formula (1), R 11 ~R 18 Examples of the aralkyl group include the same groups as the aralkyl group represented by the following formula: In general formula (2), R 21 ~R 28 The aryl group represented by the formula (1) includes R 11 ~R 18 The aryl group may be the same as the aryl group represented by the following formula: In general formula (2), R 21 ~R 28 The aryloxy group represented by the formula (1) includes R 11 ~R 18 Examples of the aryloxy group include the same groups as the aryloxy group represented by the following formula: In general formula (2), R 21 ~R 28 The alkoxycarbonyl group represented by the formula (1) includes R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the alkoxycarbonyl group represented by the following formula: In general formula (2), R 21 ~R28 The aryloxycarbonyl group represented by the formula (1) includes R 11 ~R 18 Examples of the aryloxycarbonyl group include the same groups as the aryloxycarbonyl group represented by the following formula: In general formula (2), R 21 ~R 28 The alkoxycarbonyl alkyl group represented by the formula (1) includes R 11 ~R 18 Examples of the alkoxycarbonylalkyl group include the same groups as those represented by the following formula: In general formula (2), R 21 ~R 28 The aryloxycarbonylalkyl group represented by the formula (1) includes R 11 ~R 18 Examples of the aryloxycarbonylalkyl group include the same groups as the aryloxycarbonylalkyl group represented by the following formula: In general formula (2), R 21 ~R 28 The halogen atom represented by the formula (1) is R 11 ~R 18 Examples of the halogen atom include the halogen atoms represented by the following formula:

[0105] In general formula (2), R 21 and R 22 , R 22 and R 23 , R 23 and R 24 , R 25 and R 26 , R 26 and R 27 or R 27 and R 28 However, examples of the ring structure formed by linking together include a benzene ring and a fused ring having 10 to 18 carbon atoms (such as a naphthalene ring, an anthracene ring, a phenanthrene ring, a chrysene ring (benzo[α]phenanthrene ring), a tetracene ring, a tetraphene ring (benzo[α]anthracene ring), and a triphenylene ring). Among these, a benzene ring is preferred as the ring structure formed.

[0106] In general formula (1), R 11 , R 12 , R13 , R 14 , R 15 , R 16 , R 17 and R 18 are preferably each independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group.

[0107] In general formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 are preferably each independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group.

[0108] Specific examples of the compounds represented by general formula (1) or general formula (2) are shown below, but the present embodiment is not limited to these.

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] The compound represented by general formula (1) and the compound represented by general formula (2) are isomers (i.e., cis and trans isomers). A common synthesis method involves heating and condensing two moles of an orthophenylenediamine compound with one mole of a naphthalenetetracarboxylic acid compound, resulting in a mixture of cis and trans isomers, with the cis isomer usually being present in a higher proportion than the trans isomer. The cis and trans isomers can be separated, for example, by washing with an alcoholic solution of potassium hydroxide under heating to separate the soluble cis isomer from the poorly soluble trans isomer.

[0116] <Compound represented by general formula (3)> The compound represented by general formula (3) will be explained below.

[0117] [ka]

[0118] In general formula (3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 (Hereafter, simply "R 31 ~R 36 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0119] In general formula (3), R 31 ~R 36 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group and halogen atom represented by the formula (1) are 11 ~R 18Examples of the alkyl group include the alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group, and halogen atom represented by the following formula:

[0120] In general formula (3), R 31 ~R 36 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I).

[0121] Exemplary compounds of the compound represented by general formula (3) are shown below, but the present embodiment is not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (3-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (3-5)."

[0122] [ka]

[0123] The abbreviations in the above exemplary compounds have the following meanings. Pr: n-propyl group c-C6H 11 : Cyclohexyl group C6H5: Phenyl group p-Cl-C6H4: parachlorophenyl group CH2C6H5: benzyl group CH2CH2C6H5: Phenethyl group

[0124] <Compound represented by general formula (4)> The compound represented by general formula (4) will be explained below.

[0125] [ka]

[0126] In general formula (4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 (Hereafter, simply "R 41 ~R 50 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0127] In general formula (4), R 41 ~R 50 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group and halogen atom represented by the formula (1) are 11 ~R 18 Examples of the alkyl group include the alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group, and halogen atom represented by the following formula:

[0128] In general formula (4), R 41 ~R 50 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I).

[0129] Exemplary compounds of the compound represented by general formula (4) are shown below, but the present embodiment is not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (4-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (4-5)."

[0130] [ka]

[0131] The abbreviations in the above exemplary compounds have the following meanings. Bu: n-butyl group c-C6H 11 : Cyclohexyl group p-CH3-C6H4: para-tolyl group C6H5: Phenyl group p-Cl-C6H4: parachlorophenyl group o-Cl-C6H4: orthochlorophenyl group CH2C6H5: benzyl group 3,5-(CH3)2-C6H3: 3,5-dimethylphenyl group 3,5-Cl2-C6H3: 3,5-dichlorophenyl group

[0132] <Compound represented by general formula (5)> The compound represented by general formula (5) will be explained below.

[0133] [ka]

[0134] In general formula (5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 (Hereinafter referred to as “R 51 ~R 58 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0135] In general formula (5), R 51 ~R 58 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group and halogen atom represented by the formula (1) are 11 ~R 18Examples of the alkyl group include the alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group, and halogen atom represented by the following formula:

[0136] In general formula (5), R 51 ~R 58 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I).

[0137] In general formula (5), R 51 ~R 58 may each independently be represented by a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group.

[0138] In general formula (5), R 51 and R 58 are each independently, from the viewpoint of further suppressing the residual potential, preferably an alkyl group having from 3 to 12 carbon atoms, an alkoxy group having from 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having from 3 to 12 carbon atoms, a branched alkoxy group having from 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; still more preferably a branched alkyl group having from 3 to 8 carbon atoms or a branched alkoxy group having from 3 to 8 carbon atoms; and particularly preferably a t-butyl group.

[0139] In general formula (5), R 52 and R 57are each independently, from the viewpoint of further suppressing the residual potential, preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a linear alkoxy group having 1 to 4 carbon atoms, even more preferably a linear alkyl group having 1 to 3 carbon atoms or a linear alkoxy group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0140] In general formula (5), R 53 , R 54 , R 55 and R 56 preferably represents a hydrogen atom. In general formula (5), R 51 and R 58 are preferably the same group from the viewpoint of further suppressing the residual potential. In general formula (5), R 52 and R 57 are preferably the same group from the viewpoint of further suppressing the residual potential. In general formula (5), R 51 and R 52 are preferably different groups from the viewpoint of further suppressing the residual potential. In general formula (5), R 57 and R 58 are preferably different groups from the viewpoint of further suppressing the residual potential.

[0141] Exemplary compounds of the compound represented by general formula (5) are shown below, but the present embodiment is not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (5-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (5-5)."

[0142] [ka]

[0143] The abbreviations in the above exemplary compounds have the following meanings. t-C4H9: t-butyl group OCH3: methoxy group t-C4H9O: t-butoxy group c-C6H 11 : Cyclohexyl group C6H5: Phenyl group CH2C6H5: benzyl group

[0144] <Compound represented by general formula (6)> The compound represented by general formula (6) will be explained below.

[0145] [ka] In general formula (6), R 61 , R 62 , R 63 and R 64 (Hereafter, simply "R 61 ~R 64 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0146] In general formula (6), R 61 ~R 64 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group and halogen atom represented by the formula (1) are 11 ~R 18 Examples of the alkyl group include an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, and a halogen atom represented by the following formula:

[0147] In general formula (6), R 61 ~R 64 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I).

[0148] In general formula (6), R 61 ~R 64 may each independently be represented by a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group.

[0149] In general formula (6), R 61 and R 64 are each independently, from the viewpoint of further suppressing the residual potential, preferably an alkyl group having from 3 to 12 carbon atoms, an alkoxy group having from 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having from 3 to 12 carbon atoms, a branched alkoxy group having from 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; still more preferably a branched alkyl group having from 3 to 8 carbon atoms or a branched alkoxy group having from 3 to 8 carbon atoms; and particularly preferably a t-butyl group.

[0150] In general formula (6), R 62 and R 64 are each independently, from the viewpoint of further suppressing the residual potential, preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a linear alkoxy group having 1 to 4 carbon atoms, even more preferably a linear alkyl group having 1 to 3 carbon atoms or a linear alkoxy group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0151] In general formula (6), R 61 and R 64 are preferably the same group. In general formula (6), R 62 and R 63 are preferably the same group. In general formula (6), R 61 and R 62 are preferably different groups. In general formula (6), R 63 and R64 are preferably different groups.

[0152] Exemplary compounds of the compound represented by general formula (6) are shown below, but the present embodiment is not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (6-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (6-5)."

[0153] [ka]

[0154] The abbreviations in the above exemplary compounds have the following meanings. t-C4H9: t-butyl group OCH3: methoxy group t-C4H9O: t-butoxy group c-C6H 11 : Cyclohexyl group C6H5: Phenyl group CH2C6H5: benzyl group

[0155] <Compound represented by general formula (7)> The compound represented by general formula (7) will be explained below.

[0156] [ka]

[0157] In general formula (7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 (Hereinafter referred to as “R 71 ~R 78") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0158] In general formula (7), R 71 ~R 78 Examples of the alkyl group represented by the formula (I) include linear or branched alkyl groups having 1 to 4 carbon atoms (preferably 1 to 3), and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and the like. In general formula (7), R 71 ~R 78 Examples of the alkoxy group represented by the formula (I) include alkoxy groups having 1 to 4 carbon atoms (preferably 1 to 3 carbon atoms), and specific examples include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

[0159] In general formula (7), R 71 ~R 78 Examples of the aralkyl group represented by the formula include a group represented by -L-Ar, where L represents an alkylene group and Ar represents an aryl group. The alkylene group represented by L includes linear or branched alkylene groups having from 1 to 12 carbon atoms, such as a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an n-pentylene group, an isopentylene group, a neopentylene group, and a tert-pentylene group. Examples of the aryl group represented by Ar include a phenyl group, a methylphenyl group, a dimethylphenyl group, and an ethylphenyl group. In general formula (7), R 71 ~R 78 Specific examples of the aralkyl group represented by the formula (I) include a benzyl group, a methylbenzyl group, a dimethylbenzyl group, a phenylethyl group, a methylphenylethyl group, a phenylpropyl group, and a phenylbutyl group.

[0160] In general formula (7), R 71 ~R 78 Examples of the aryl group represented by the formula (I) include a phenyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, etc. Among these, a phenyl group is preferred.

[0161] In general formula (7), R 71 ~R 78 The acyl group (-C(=O)-R AC , the R AC represents a hydrocarbon group.) includes, for example, an acyl group having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 3), and specific examples thereof include an acetyl group, a propanoyl group, a benzoyl group, and a cyclohexanecarbonyl group.

[0162] In general formula (7), R 71 ~R 78 The alkoxycarbonyl group represented by the formula (1) is R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the alkoxycarbonyl group represented by the following formula:

[0163] In general formula (7), R 71 ~R 78 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I). In general formula (7), R 71 ~R 78 The acyl group represented by R in general formula (1) 11 ~R 18 The alkyl group may have the same substituents as those mentioned for the alkyl group represented by the following formula:

[0164] In general formula (7), R 71 ~R 78 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0165] In general formula (7), R 78 The group represented by the formula (I) is an alkoxycarbonyl group (-C(=O)-OR 78A ) is preferred. 78A is an alkyl group having 8 or more carbon atoms (long chain alkyl group) or -L 181 -OR 182 indicates L 181 represents an alkylene group, and R 182 indicates an alkyl group having 8 or more carbon atoms (long-chain alkyl group).

[0166] In general formula (7), R 78 -L 181 -OR 182 The group represented by L 181 represents an alkylene group, and R 182 indicates an alkyl group having 8 or more carbon atoms (long-chain alkyl group).

[0167] L 181 Examples of the alkylene group represented by the formula (I) include linear or branched alkylene groups having 1 to 12 carbon atoms, such as a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an n-pentylene group, an isopentylene group, a neopentylene group, and a tert-pentylene group.

[0168] R 182 The long-chain alkyl group represented by the formula (I) is not particularly limited as long as it has 8 or more carbon atoms, and from the viewpoint of suppressing cracking of the photosensitive layer, it preferably has 8 or more and 12 or less carbon atoms. Furthermore, the long-chain alkyl group may be linear or branched, and is preferably linear. Examples of the linear alkyl group having 8 to 12 carbon atoms include an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, and an n-dodecyl group. Examples of branched alkyl groups having 8 to 12 carbon atoms include isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, and tert-decyl groups.

[0169] The compound represented by general formula (7) may have only one long-chain alkyl group in one molecule, or may have two or more long-chain alkyl groups in one molecule. From the viewpoint of suppressing cracking of the photosensitive layer, the number of long-chain alkyl groups in one molecule of the compound represented by general formula (7) is preferably 1 to 3, more preferably 1 to 2.

[0170] In one embodiment, the compound represented by general formula (7) is a compound represented by the formula R 71 ~R 77 each independently represents a hydrogen atom, a halogen atom, or an alkyl group; R 78 is preferably a straight-chain alkyl group having 8 or less carbon atoms.

[0171] Exemplary compounds of the compound represented by general formula (7) are shown below, but are not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (7-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (7-5)."

[0172] [ka]

[0173] The abbreviations in the above exemplary compounds have the following meanings. =C(CN)2: dicyanomethylene group

[0174] <Compound represented by general formula (8)> The compound represented by general formula (8) will be explained below.

[0175] [ka]

[0176] In general formula (8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 , R 87 and R 88 (Hereafter, simply "R 81 ~R 88 ") each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0177] In general formula (8), R 81 ~R 88 The alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group and halogen atom represented by the formula (7) are R 71 ~R 78 Examples of the alkyl group include an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, and a halogen atom represented by the following formula:

[0178] In general formula (8), R 81 ~R 88 The alkyl group, alkoxy group, aralkyl group, aryl group and alkoxycarbonyl group represented by R 11 ~R 18 and the like. The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I) may have the same substituents as those exemplified for the alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by the following formula (I). In general formula (8), R 81 ~R 88 The acyl group represented by R in general formula (1) 11 ~R 18 The alkyl group may have the same substituents as those mentioned for the alkyl group represented by the following formula:

[0179] Exemplary compounds of the compound represented by general formula (8) are shown below, but are not limited thereto. The following exemplary compound numbers are hereinafter referred to as exemplary compound (8-number). Specifically, for example, exemplary compound 5 is hereinafter referred to as "exemplary compound (8-5)."

[0180] [ka]

[0181] The abbreviations in the above exemplary compounds have the following meanings. C(=O)CH3: acetyl group OCH3: methoxy group CN: Cyano group CH2C6H5: benzyl group =C(CN)2: dicyanomethylene group

[0182] The content of the electron transport material is preferably 50% by mass to 80% by mass, more preferably 55% by mass to 75% by mass, and even more preferably 60% by mass to 70% by mass, based on the total solid content of the undercoat layer. When two or more electron transport materials are used in combination, the content of the electron transport material means the total amount of the two or more electron transport materials. When the content of the electron transport material is 80% by mass or less, the film becomes brittle, film-forming properties deteriorate, and the occurrence of surface roughness of the undercoat layer is suppressed, resulting in excellent charge retention.On the other hand, when the content of the electron transport material is 50% by mass or more, excess or deficiency in electron transport ability is suppressed, and residual potential is further suppressed.

[0183] -Butyral resin- When the composition contains a butyral resin, the content of the butyral resin is 5% by mass or less, preferably 4% by mass or less, and more preferably 3% by mass or less, based on the total solid content of the undercoat layer. The composition may contain 0% by mass of butyral resin, i.e., it may not contain any butyral resin. When the butyral resin content in the composition is 5% by mass or less, or when the composition does not contain a butyral resin, the electron transport material and the hole transport compound in the undercoat layer are easily dispersed with high uniformity, and the coating liquid stability and film formability are improved, which is preferable. This makes it easier to obtain a photoreceptor with good charge retention and reduced residual potential.

[0184] - Hardener - The composition includes a curing agent. By including a curing agent in the composition, the curing agent reacts with the triarylamine compound having a reactive group to form a cured film, thereby suppressing the residual potential.

[0185] The curing agent preferably contains at least one of an isocyanate compound and a melamine resin, and more preferably contains an isocyanate compound. When an isocyanate compound is contained as a curing agent, the isocyanate compound reacts more efficiently with the triarylamine compound having a reactive group to form a cured film, which has better charge retention and is more likely to suppress the residual potential. When a curing agent containing either a melamine resin or a benzoguanamine resin is used, the resin easily prevents holes from being injected into the charge-generating material (i.e., has a high hole-blocking effect) when the cured film is formed, and therefore the potential on the photoreceptor surface is less likely to decay.

[0186] Examples of the isocyanate compound include: Diisocyanates such as methylene diisocyanate, ethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethylbiphenylene diisocyanate, 4,4'-biphenylene diisocyanate, dicyclohexylmethane diisocyanate, and methylenebis(4-cyclohexylisocyanate); isocyanurates formed by trimerization of the above diisocyanates; a blocked isocyanate obtained by blocking the isocyanate group of the diisocyanate with a blocking agent such as methyl ethyl ketone oxime, phenol, or alcohol; Examples include: Among the above, preferred isocyanate compounds are polyfunctional compounds having a plurality of isocyanate groups, such as isocyanurates, blocked isocyanates, etc. Blocked isocyanates are particularly preferred from the viewpoints of manufacturability and stability. From the viewpoint of further improving film-forming properties, the isocyanate compound is preferably an oligomer or a resin.

[0187] Examples of the curing agent other than the isocyanate compound, melamine resin, and benzoguanamine resin include polyols other than butyral resins.

[0188] Examples of polyols other than butyral resins include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 3,3-dimethyl-1,2-butanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,2-diethyl-1,3-propanediol, and 2,4-dimethyl-2, Examples of diols include 4-pentanediol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, hydroquinone, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, poly(oxytetramethylene) glycol, 4,4'-dihydroxydiphenyl-2,2-propane, and 4,4'-dihydroxyphenyl sulfone. Further examples of polyols other than butyral resins include polyester polyols, polycarbonate polyols, polycaprolactone polyols, and polyether polyols. One type of polyol may be used, or two or more types may be used in combination.

[0189] -Curing catalyst- Examples of the curing catalyst include amine compounds, organic acid metal salts, and organic metal complexes. Examples of the amine compound include 1,4-diazabicyclo(2,2,2)octane, N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N,N',N'-tetramethylpropylenediamine, N-ethylmorpholine, N-methylmorpholine, N,N-dimethylethanolamine, 1,8-diazabicyclo[5,4,0]undecene-7 (DBU), and salts thereof. Examples of organic acid metal salts or organic metal complexes include dibutyltin laurate, stannous octoate, bismuth octoate, bismuth naphthenate, bismuth salicylate, zinc octoate, zinc naphthenate, and zinc salicylate. Commercially available urethane curing catalysts include, for example, the K-KAT series manufactured by King Industries Co., Ltd.; bismuth carboxylate catalysts such as K-KAT348, K-KAT XC-C227, K-KAT XK-628, and K-KAT XK-640; aluminum complex catalysts such as K-KAT5218; zirconium complex catalysts such as K-KAT4205, K-KAT6212, and K-KATA209; and titanium complex catalysts such as TA-30 and TC-750 from the Orgatics series manufactured by Matsumoto Fine Chemical Co., Ltd.

[0190] The resin contained in the undercoat layer is preferably polyurethane in an amount of 80% by mass or more and 100% by mass or less of the total amount of resin, more preferably polyurethane in an amount of 90% by mass or more and 100% by mass or less, and even more preferably polyurethane in an amount of 95% by mass or more and 100% by mass or less.

[0191] The mass ratio of the total content of the electron transport material contained in the undercoat layer to the content of the polyurethane contained in the undercoat layer (electron transport material:polyurethane) is preferably 90:10 to 50:50, more preferably 80:20 to 70:30.

[0192] -Inorganic particles- The composition may further comprise inorganic particles. As inorganic particles, for example, powder resistance (volume resistivity) 10 2 Ωcm or more 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.

[0193] The specific surface area of ​​inorganic particles measured by the BET method is, for example, 10 m 2 / g or more is preferable. 2 When the molecular weight is 1 / g or more, the decrease in chargeability tends to be suppressed. 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).

[0194] The content of the inorganic particles is, for example, preferably from 0% to 80% by mass, more preferably from 0% to 70% by mass, based on the total solid content of the undercoat layer.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] The dry method is a method in which, while stirring inorganic particles using a mixer or the like with high shear force, a surface treatment agent is added dropwise, either directly or dissolved in an organic solvent, or sprayed together with dry air or nitrogen gas to adhere the surface treatment agent to the surfaces of the inorganic particles. The surface treatment agent is preferably added dropwise or sprayed at a temperature below the boiling point of the solvent. After the surface treatment agent is 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.

[0202] The wet method is a method in which inorganic particles are dispersed in a solvent using, for example, stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, or the like, while a surface treatment agent is added, and after stirring or dispersing, the solvent is removed to adhere the surface treatment agent 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 surface treatment agent. Examples of such methods include a method in which the inorganic particles are removed by stirring and heating in a solvent, and a method in which the inorganic particles are removed by azeotropy with the solvent.

[0203] -Additives- 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0208] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0209] -Other properties of the undercoat layer- The volume resistivity of the undercoat layer is 1×10 10 Ωcm or more 1×10 12 It is preferably Ωcm or less.

[0210] 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 moiré 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.

[0211] - Method for forming undercoat layer - The formation of the undercoat layer is not particularly limited, and a well-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.

[0212] 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.

[0213] 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. Since electron transport materials (particularly compounds represented by general formulas (1) to (8)) are difficult to dissolve in organic solvents, it is desirable to disperse them in an organic solvent. Examples of dispersion methods include known methods such as a roll mill, ball mill, vibrating ball mill, attritor, sand mill, colloid mill, and paint shaker. When metal oxide particles are incorporated into the undercoat layer, it is desirable to disperse the metal oxide particles in an organic solvent using a similar dispersion method.

[0214] 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.

[0215] The thickness of the undercoat layer is preferably 1 μm or more, and more preferably 3 μm or more. The thickness of the undercoat layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less, from the viewpoint of achieving better charge retention.

[0216] (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 10 13 This means that the resistance is less than Ωcm.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] (middle class) Although not shown, 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.

[0225] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0226] The formation of the intermediate layer is not particularly limited, and a well-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.

[0227] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm. The intermediate layer may also be used as an undercoat layer.

[0228] (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.

[0229] 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.

[0230] 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, specifically, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine, for example.

[0231] 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.

[0232] 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.

[0233] In contrast, when n-type semiconductors such as fused-ring aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark current is less likely to occur, and image defects known as black spots can be suppressed even when the material is thin. Note that n-type is determined by the commonly used time-of-flight method, based on the polarity of the photocurrent that flows, and materials that more easily pass electrons as carriers than holes are considered n-type.

[0234] 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 (polycondensation product of bisphenols and aromatic dicarboxylic acids, etc.), 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 resin having a volume resistivity of 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.

[0235] 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.

[0236] The charge generating layer may contain other well-known additives.

[0237] The formation of the charge generation layer is not particularly limited, and a well-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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] (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.

[0243] 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 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.

[0244] As the charge transport material, triarylamine derivatives represented by the following structural formula (a-1) and benzidine derivatives represented by the following structural formula (a-2) are preferred from the viewpoint of charge mobility.

[0245] [ka]

[0246] In structural formula (a-1), Ar T1 , ArT2 , and Ar T3 are each independently a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) indicates R T4 , R T5 , R T6 , R T7 , and R T8 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituents on each of the above groups include halogen atoms, alkyl groups having from 1 to 5 carbon atoms, and alkoxy groups having from 1 to 5 carbon atoms. Examples of the substituents on each of the above groups also include substituted amino groups substituted with alkyl groups having from 1 to 3 carbon atoms.

[0247] [ka]

[0248] In structural formula (a-2), R T91 and R T92 R each independently represents 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. T101 , R T102 , R T111 and R T112 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 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) and R T12 , R T13 , R T14 , R T15 and R T16each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less. Examples of the substituents on each of the above groups include halogen atoms, alkyl groups having from 1 to 5 carbon atoms, and alkoxy groups having from 1 to 5 carbon atoms. Examples of the substituents on each of the above groups also include substituted amino groups substituted with alkyl groups having from 1 to 3 carbon atoms.

[0249] Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 ) is preferred from the viewpoint of charge mobility.

[0250] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0251] Examples of binder resins used in the charge transport layer include polycarbonate resins, polyester resins, polyarylate resins, 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. Among these, polycarbonate resins or polyarylate resins are preferred as binder resins. These binder resins may be used alone or in combination of two or more. The compounding ratio of the charge transport material to the binder resin is preferably from 10:1 to 1:5 by mass.

[0252] The charge transport layer may contain other well-known additives.

[0253] The formation of the charge transport layer is not particularly limited, and a well-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.

[0254] 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.

[0255] 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.

[0256] The thickness of the charge transport layer is set, for example, preferably in the range of 5 μm to 50 μm, more preferably 10 μm to 30 μm.

[0257] (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).

[0258] 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).

[0259] 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; Qn represents an integer of 1 to 3.

[0260] 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 styryl group (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 styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof is preferred as the chain polymerizable group because of its excellent reactivity.

[0261] The charge transporting skeleton of the reactive group-containing charge transporting 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 transporting 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.

[0262] 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.

[0263] The protective layer may also contain other well-known additives.

[0264] The formation of the protective layer is not particularly limited, and a well-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.

[0265] 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 protective layer-forming coating liquid may be a solvent-free coating liquid.

[0266] 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.

[0267] 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.

[0268] (single-layer photosensitive layer) The single-layer photosensitive layer (charge generation / charge transport layer) is a layer containing, for example, a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. Note that these materials are the same as those described for the charge generation layer and the charge transport layer. The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass to 10% by mass, more preferably 0.8% by mass to 5% by mass, based on the total solid content, and the content of the charge transport material in the single-layer photosensitive layer is preferably 5% by mass to 50% by mass, based on the total solid content. 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. The thickness of the single-layer photosensitive layer is, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 40 μm or less.

[0269] [Image forming device (and 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.

[0270] 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 to eliminate charges 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.

[0271] 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.

[0272] 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).

[0273] 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 also include 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.

[0274] 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. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0275] FIG. 2 is a schematic diagram showing an example of the configuration of an image forming apparatus according to this embodiment. As shown in FIG. 2, the image forming apparatus 100 according to this 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.

[0276] 2 integrally supports within a housing 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). 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.

[0277] Note that FIG. 2 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, but these may be arranged as needed.

[0278] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0279] -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.

[0280] -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.

[0281] -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.

[0282] 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. Well-known developers are used.

[0283] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131 . In addition to the cleaning blade system, a fur brush cleaning system or a simultaneous development and cleaning system may also be used.

[0284] -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.

[0285] -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.

[0286] FIG. 3 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. 3 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]

[0287] The electrophotographic photoreceptor of the present disclosure will be described in more detail below with reference to examples. The materials, amounts used, ratios, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present disclosure. Therefore, the scope of the electrophotographic photoreceptor of the present disclosure should not be interpreted as being limited by the specific examples shown below.

[0288] As triarylamine compounds having a reactive group used in the examples and comparative examples, the exemplary compounds having the corresponding exemplary numbers in the specification and the following amine compounds were prepared.

[0289] -Amine compound for comparison- Amine compound (c1): 3,4-dimethyldiphenylamine (the compound shown below)

[0290] [ka]

[0291] -Preparation of electron transport material- As the electron transporting materials used in the examples and comparative examples, the respective exemplary compounds having the corresponding exemplary numbers in the specification were prepared.

[0292] -Types of curing agents and resins contained in the composition- Blocked isocyanate (Sumidur BL3175, manufactured by Sumika Covestro Urethane Co., Ltd., solid content 75% by mass) Blocked isocyanate (Desmodur BL3475, manufactured by Sumika Covestro Urethane Co., Ltd., solid content 75% by mass) Blocked isocyanate (Desmodur BL3370, manufactured by Sumika Covestro Urethane Co., Ltd., solid content 70% by mass) Butyral resin (Sekisui Chemical Co., Ltd., S-LEC BL-1) Methylated melamine resin (Sanwa Chemical, MW-30)

[0293] [Example 1] (Formation of Undercoat Layer) 46.7 parts by weight of the isocyanate compound blocked isocyanate BL3175 (75% solids content) as a curing agent and 5 parts by weight of a triarylamine compound (I-1) having a reactive group were dissolved in 100 parts by weight of methyl ethyl ketone and 100 parts by weight of cyclopentanone. 60 parts by weight of the electron transport material (I-1) shown in the table was added to this solution and dispersed in a sand mill using 1 mm diameter glass beads for 240 minutes to obtain a dispersion. 0.001 parts by weight of bismuth carboxylate (K-KAT XK-640, King Industries) was added as a catalyst to the resulting dispersion to obtain a coating solution for the undercoat layer. This coating solution was dip-coated onto a cylindrical aluminum substrate and dried and cured at 160°C for 45 minutes to form a 4.2 μm thick undercoat layer.

[0294] (Formation of Charge Generation Layer) Hydroxygallium phthalocyanine was used as a charge-generating material. Its X-ray diffraction spectrum using CuKα characteristic X-rays exhibits diffraction peaks at Bragg angles (2θ ±0.2°) of at least 7.5°, 16.3°, 25.0°, and 28.3°. A mixture of 15 parts by weight of hydroxygallium phthalocyanine, 10 parts by weight of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.), and 200 parts by weight of n-butyl acetate was dispersed in a sand mill using 1 mm diameter glass beads for 4 hours. To the resulting dispersion, 175 parts by weight of n-butyl acetate and 180 parts by weight of methyl ethyl ketone were added and stirred to obtain a coating solution for forming a charge-generating layer. This coating solution was dip-coated onto the undercoat layer and dried at 150°C for 12 minutes to form a 0.2 μm-thick charge-generating layer.

[0295] (Formation of charge transport layer) 38 parts by weight of charge transport agent (HT-1), 10 parts by weight of charge transport agent (HT-2), and 52 parts by weight of polycarbonate (A) (viscosity average molecular weight 48,000) were dissolved in 800 parts by weight of tetrahydrofuran, and 8 parts by weight of tetrafluoroethylene resin (Lubron L5, manufactured by Daikin Industries, Ltd., average particle size 300 nm) was added. The mixture was dispersed for 2 hours at 5,500 rpm using a homogenizer (Ultra-Turrax, manufactured by IKA Corporation) to obtain a coating solution for forming a charge transport layer. This coating solution was dip-coated onto the charge generation layer and dried at 140°C for 40 minutes to form a 26 μm-thick charge transport layer. Through the above process, an electrophotographic photoreceptor of Example 1 was obtained.

[0296] [ka]

[0297] [ka]

[0298] [Examples 2 to 21, Comparative Examples 1 to 3] A photoreceptor was prepared in the same manner as in Example 1, except that in forming the undercoat layer, the type and amount of the triarylamine compound having a reactive group, the type and amount of the electron transport material, the type and amount of the curing agent, and the type and amount of the butyral resin were set to the specifications shown in Table 1. In the table, a "-" next to each item indicates that the material in that item was not used. The amount of each material shown in the table is the amount relative to the total solid content of the undercoat layer.

[0299] <Photoreceptor performance evaluation> The photoreceptor of each example or comparative example was mounted in an image forming apparatus DocuCentre C5570 manufactured by Fuji Xerox Co., Ltd., and the following performance evaluations were carried out in an environment of a temperature of 30° C. and a relative humidity of 85%. The evaluation results are shown in the tables.

[0300] [Residual potential evaluation] The photoconductor obtained in each example was rotated at 100 rpm and charged to -700 V using a scorotron charger. 0.05 seconds after charging, a semiconductor laser with a wavelength of 780 nm was used to irradiate the photoconductor with 2.0 mJ / m 2 Then, 0.1 seconds after the discharge, the photoconductor was irradiated with 20 mJ / m 2 The potential V of the surface of the photoconductor was measured 100 msec after the discharge, and this was taken as the residual potential value. -Evaluation criteria- G1: -50V or more G2: Less than -50V -70V or more G3: Less than -70V -100V or more G4: Less than -100V

[0301] [Charge retention] The surface potential probe of a surface potential meter (Trek 334, manufactured by Trek) was placed at a position 1 mm away from the surface of the photoreceptor. The surface of the photoreceptor was charged to -700 V, and then the amount of potential drop (amount of dark decay) after 0.1 seconds was measured, and the amount of potential drop was classified into A to C as follows. -Evaluation criteria- G1: Voltage drop less than 15V G2: Voltage drop is 15V or more but less than 18V G3: Voltage drop is 18V or more but less than 20V G4: Potential drop of 20V or more

[0302] [Environmental stability of charge retention] The environment of 30°C temperature and 85% relative humidity was changed to an environment of 15°C temperature and 10% relative humidity, and the charge retention was measured. The difference in the measured value (amount of potential change) between the two environments was classified into the following categories A to C. -Evaluation criteria- G1: The potential change is less than 5V G2: Potential change is 5V or more but less than 7V G3: Potential change is 7V or more G4: Potential change is 10V or more

[0303] [Table 1]

[0304] [Table 2]

[0305] As shown in each table, it was found that the electrophotographic photoreceptors of Examples were superior in charge retention and had reduced residual potential compared to the electrophotographic photoreceptors of Comparative Examples. It was also found that the electrophotographic photoreceptors of Examples were superior in environmental stability of charge retention compared to the electrophotographic photoreceptors of Comparative Examples. [Explanation of symbols]

[0306] 1 undercoat layer, 2 charge generation layer, 3 charge transport layer, 4 conductive substrate, 5 photosensitive layer, 7A electrophotographic photosensitive member, 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer member, 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; an undercoat layer disposed on the conductive substrate; a photosensitive layer disposed on the undercoat layer; Equipped with the undercoat layer is composed of a cured product of a composition that includes a triarylamine compound having a reactive group, a curing agent, and an electron transport material, and in which a butyral resin content relative to a total solid content of the undercoat layer is 0% by mass or more and 5% by mass or less; the content of the triarylamine compound having a reactive group is 0.1% by mass or more and 8% by mass or less with respect to the total solid content of the undercoat layer, The electrophotographic photoreceptor includes a hole transport compound represented by the following general formula (I), wherein the triarylamine compound having a reactive group is a hole transport compound represented by the following general formula (I): 【Chemistry 1】 (In the general formula (I), R １ , R ２ and R ３ are each independently a hydrogen atom, a hydroxy group, a hydroxyalkyl group having 1 to 6 carbon atoms, an amino group (NH ２ group), a thiol group, an alkylthiol group, a carboxy group, or a carboxyalkyl group (provided that R 1 , R 2 , and R 3 cannot all be hydrogen atoms). X １ , X ２ and X ３ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an ester group, an aryl group, an aralkyl group, or a vinylphenyl group.

2. In the general formula (I), R １ , R ２ and R ３ are each independently a hydrogen atom, a hydroxy group, a hydroxyalkyl group having 1 to 4 carbon atoms, an amino group (NH ２ group), a carboxy group, or a carboxyalkyl group having from 1 to 4 carbon atoms (provided that R 1 , R 2 and R 3 cannot all be hydrogen atoms). X １ , X ２ and X ３ and each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, or a vinylphenyl group.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein the electron transport material comprises at least one electron transport material selected from the group consisting of compounds represented by the following general formulas (1), (2), (3), (4), (5), (6), (7), and (8): In general formula (1), R １１ , R １２ , R １３ , R １４ , R １５ , R １６ , R １７ and R １８ R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. １１ and R １２ , R １２ and R １３ and R １３ and R １４ may each independently be linked to each other to form a ring. １５ and R １６ , R １６ and R １７ and R １７ and R １８ may each independently be linked to each other to form a ring. In general formula (2), R ２１ , R ２２ , R ２３ , R ２４ , R ２５ , R ２６ , R ２７ and R ２８ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, or an aryl group. R represents a group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. ２１ and R ２２ , R ２２ and R ２３ and R ２３ and R ２４ may each independently be linked to each other to form a ring. ２５ and R ２６ , R ２６ and R ２７ and R ２７ and R ２８ may each independently be linked to each other to form a ring. In general formula (3), R ３１ , R ３２ , R ３３ , R ３４ , R ３５ and R ３６ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (4), R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , R ４６ , R ４７ , R ４８ , R ４９ and R ５０ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (5), R ５１ , R ５２ , R ５３ , R ５４ , R ５５ , R ５６ , R ５７ and R ５８ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (6), R ６１ , R ６２ , R ６３ and R ６４ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom. In general formula (7), R ７１ , R ７２ , R ７３ , R ７４ , R ７５ , R ７６ , R ７７ and R ７８ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom; Z represents an oxygen atom or a dicyanomethylene group (═C(CN) ２ ) represents In general formula (8), R ８１ , R ８２ , R ８３ , R ８４ , R ８５ , R ８６ , R ８７ and R ８８ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, or a halogen atom; Z represents an oxygen atom or a dicyanomethylene group (═C(CN) ２ ) represents 【Chemistry 2】

4. 4. The electrophotographic photoreceptor according to claim 1, wherein the content of the electron transport material is 50% by mass or more and 80% by mass or less based on the total solid content of the undercoat layer.

5. An electrophotographic photoreceptor according to any one of claims 1 to 4, A process cartridge that is detachably attached to an image forming apparatus.

6. The electrophotographic photoreceptor according to any one of claims 1 to 4, a charging means for charging the surface of the electrophotographic photosensitive member; an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member; a developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing a toner to form a toner image; a transfer means for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

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