Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in electrification characteristics and electron transport properties.SOLUTION: An electrophotographic photoreceptor has an undercoat layer and a photosensitive layer on a conductive support. The undercoat layer includes crystalline electron transport compound particles. The half-width of the maximum intensity peak in X-ray diffraction measurement obtained by measuring the undercoat layer from a thickness direction is 5° or less. When the relative integrated intensity of peaks in the X-ray diffraction measurement obtained by measuring the undercoat layer from the thickness direction is defined as I1, and the relative integrated intensity of peaks in the X-ray diffraction measurement obtained by measuring the undercoat layer in a powder state with a volume average particle diameter of 5 μm or less as I2, the value of the maximum value Nmax in an orientation index N represented by the following formula (1) is 1 or more and 3 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 describes an electrophotographic photoreceptor having, in this order, a support, a charge generation layer containing a hydroxygallium phthalocyanine pigment as a charge generation material, and a charge transport layer containing a charge transport material, wherein the thickness of the charge generation layer is greater than 200 nm, and the hydroxygallium phthalocyanine pigment has an X-ray diffraction spectrum using CuKα rays. An electrophotographic photoreceptor is disclosed, characterized in that it has peaks at 7.4°±0.3° and 28.2°±0.3° (Bragg angle 2θ), and A, which is calculated by equation (1) from the angle θ1[°] and integral width β1[°] of the peak at 7.4°±0.3° and the angle θ2[°] and integral width β2[°] of the peak at 28.2°±0.3°, is 0.8 or less.

[0003]

number

[0004] Patent Document 2 discloses an electrophotographic photoreceptor characterized by having a photosensitive layer containing a charge generating agent on a conductive support, wherein the charge generating agent is obtained by sublimation purification and dry grinding of a benzimidazole perylene pigment represented by the following structural formula (I) or (II), and in X-ray diffraction measurement of the powder in an unoriented state using CuKα rays as a light source, the electrophotographic photoreceptor has a crystalline form with Bragg angles (2θ±0.2°) of 2θ=6.2°, 12.3°, and 26.8°, and the full width at half maximum S(26.8°) of 26.8° is S(26.8°)≧0.5.

[0005] [ka]

[0006] Patent Document 3 discloses an electrophotographic photoreceptor having an undercoat layer and a photosensitive layer sequentially provided on a conductive support, characterized in that the undercoat layer contains an alkali metal salt of trifluoromethanesulfonic acid and a binder resin.

[0007] Patent Document 4 discloses an electrophotographic photoreceptor having a support, an undercoat, and a photosensitive layer in that order, wherein the undercoat contains a binder resin and strontium titanate particles, and the strontium titanate particles have a maximum peak at 2θ = 32.20 ± 0.20 in the CuKα characteristic X-ray diffraction pattern (θ is the Bragg angle), and the full width at half maximum of the maximum peak is 0.10 deg or more and 0.50 deg or less.

[0008] Patent Document 5 discloses an electrophotographic photoreceptor characterized in that the undercoat contains a binder resin and composite particles, the composite particles having core material particles and tin oxide coating the core material particles, the tin oxide of the composite particles having a peak at 33.90° of the Bragg angle (2θ±0.20°) in CuKα characteristic X-ray diffraction, and the full width at half maximum of the X-ray diffraction peak at Bragg angle (2θ±0.20°) = 33.90° in CuKα characteristic X-ray diffraction is 1.41° or less. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2018-189957 [Patent Document 2] Japanese Patent Application Publication No. 5-249719 [Patent Document 3] Japanese Patent Application Publication No. 10-133407 [Patent Document 4] Japanese Patent Publication No. 2019-61219 [Patent Document 5] Japanese Patent Publication No. 2015-180923 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide an electrophotographic photoreceptor that exhibits superior chargeability and electron transport properties compared to cases where the full width at half maximum of the maximum intensity peak measured in X-ray diffraction measurements of the undercoat layer from the thickness direction is greater than 5°, or the maximum value Nmax of the orientation index N represented by formula (1) described later is greater than 3, or the average aspect ratio of the crystalline electron-transporting compound particles contained in the undercoat layer is greater than 4.5. [Means for solving the problem]

[0011] Means for solving the aforementioned problem include the following embodiments. <1> An electrophotographic photoreceptor having a base layer and a photosensitive layer on a conductive support, wherein the base layer contains crystalline electron-transporting compound particles, the full width at half maximum of the maximum intensity peak in an X-ray diffraction measurement of the base layer measured from the thickness direction is 5° or less, and when I1 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the base layer measured from the thickness direction, and I2 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the base layer in a powder state with a volume-average particle size of 5 μm or less, the value of the maximum value Nmax in the orientation index N expressed by the following formula (1) is 1 or more and 3 or less.

[0012]

number

[0013] <2> The above-mentioned full width at half maximum is 1.0° or less. <1> The electrophotographic photoreceptor described above. <3> The aforementioned full width at half maximum is 0.7° or less. <2> The electrophotographic photoreceptor described above. <4> The value of the aforementioned maximum value Nmax is between 1 and 2.7. <1> ~ <3> An electrophotographic photoreceptor as described in any one of the following. <5> The value of the aforementioned maximum value Nmax is between 1 and 2.5. <4> The electrophotographic photoreceptor described above. <6> An electrophotographic photoreceptor having an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains crystalline electron transporting compound particles, and the average aspect ratio of the electron transporting compound particles is 4.5 or less. <7> The electrophotographic photoreceptor according to any one of <1> to <6>, wherein the electron transporting compound particles are particles of a compound represented by any one of the following formulas (P1) to (P8).

[0014]

Chemical formula

[0015] In formula (P1), R 28 , 26 , 27 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 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, and R 11 and R 12 , R 12 and R <T000012> and R 13 I and R 14 each independently may be linked to each other to form a ring, and R 15 and R 16 , R 16 and R 17 and R 17 and R 18 each independently may be linked to each other to form a ring. In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28Each of these 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, R 21 and R 22 , R 22 and R 23 and R 23 and R 24 Each of them may be independent, or they may be connected to each other to form a ring, R 25 and R 26 , R 26 and R 27 and R 27 and R 28 These elements may be connected to each other independently to form a ring. In formula (P3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 Each of these 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 formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 Each of these 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 formula (P5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 Each of these 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 formula (P6), R 61 , R62 , R 63 and R 64 Each of these 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 formula (P7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 and R 87 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0016] <8> The electron-transporting compound particles are particles of a compound represented by any of the above formulas (P1) to (P4). <7> The electrophotographic photoreceptor described above. <9> The electron-transporting compound particles are embodiment particles of the compound represented by formula (P4). <8> The electrophotographic photoreceptor described above. <10> The content of the electron-transporting compound particles is 50% by mass or more and 80% by mass or less, relative to the total mass of the lower layer. <1> ~ <9> An electrophotographic photoreceptor as described in any one of the following. <11> <1> ~ <10> A process cartridge equipped with an electrophotographic photoreceptor as described in any one of the following, which can be attached to and detached from an image forming apparatus. <12> <1> ~ <10> An image forming apparatus comprising: an electrophotographic photoreceptor as described in any one of the above; charging means for charging the surface of the electrophotographic photoreceptor; electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and transfer means for transferring the toner image to the surface of a recording medium. [Effects of the Invention]

[0017] <1> or <6> According to the invention, an electrophotographic photoreceptor is provided that exhibits superior chargeability and electron transport properties compared to cases where the full width at half maximum of the maximum intensity peak in an X-ray diffraction measurement of the undercoat layer measured from the thickness direction is greater than 5°, or the maximum value Nmax among the orientation index N represented by formula (1) is greater than 3, or the average aspect ratio of the crystalline electron-transporting compound particles contained in the undercoat layer is greater than 4.5. <2> According to the invention, an electrophotographic photoreceptor is provided that has superior charging properties and electron transport properties compared to the case where the full width at half maximum is greater than 1.0°. <3> According to the invention, an electrophotographic photoreceptor is provided that has superior charging properties and electron transport properties compared to the case where the full width at half maximum is greater than 0.7°. <4> According to the invention, an electrophotographic photoreceptor is provided that has superior chargeability and electron transport properties compared to the case where the maximum value Nmax is greater than 2.7. <5> According to the invention, an electrophotographic photoreceptor is provided that has superior chargeability and electron transportability compared to the case where the maximum value Nmax is greater than 2.5. <7> , <8> or <9> According to the invention, an electrophotographic photoreceptor is provided that has superior chargeability and electron transportability compared to the case where the electron-transporting compound particles are anthraquinone-based pigment particles. <10> According to the invention, an electrophotographic photoreceptor is provided that has superior chargeability and electron transportability compared to cases where the content of the electron-transporting compound particles is less than 50% by mass or more than 80% by mass relative to the total mass of the undercoat layer. <11> or <12> According to the present invention, a process cartridge and an image forming apparatus are provided that exhibit superior chargeability and electron transport properties of an electrophotographic photoreceptor compared to cases where the full width at half maximum of the maximum intensity peak in an X-ray diffraction measurement of the undercoat of the electrophotographic photoreceptor measured from the thickness direction is greater than 5°, or the maximum value Nmax among the orientation index N represented by formula (1) described later is greater than 3, or the average aspect ratio of crystalline electron-transporting compound particles contained in the undercoat is greater than 4.5. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic partial cross-sectional view showing an example of the layer structure of an electrophotographic photoreceptor according to this embodiment. [Figure 2] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 3] This is a schematic diagram showing another example of the image forming apparatus according to this embodiment. [Modes for carrying out the invention]

[0019] The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

[0020] In this disclosure, the numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively.

[0021] In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0022] In this disclosure, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, provided that its intended purpose is achieved.

[0023] In this disclosure, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in this disclosure, if there are multiple types of the substance corresponding to each component in the composition, it means the total amount of those multiple types of substances present in the composition unless otherwise specified.

[0024] In this disclosure, "main component" means the primary component. For example, in a mixture of multiple components, the main component is the component that accounts for 30% or more of the total mass of the mixture.

[0025] In this disclosure, the electrophotographic photoreceptor is also simply referred to as the photoreceptor.

[0026] <Electrophotographic photoconductor> The first embodiment of the electrophotographic photoreceptor according to this embodiment has an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains crystalline electron-transporting compound particles, the full width at half maximum of the maximum intensity peak in an X-ray diffraction measurement of the undercoat layer measured from the thickness direction is 5° or less, and when I1 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer measured from the thickness direction, and I2 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer in a powder state with a volume-average particle size of 5 μm or less, the value of the maximum value Nmax in the orientation index N expressed by the following formula (1) is 1 or more and 3 or less.

[0027]

number

[0028] A second embodiment of the electrophotographic photoreceptor according to this embodiment has an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains crystalline electron-transporting compound particles, and the average aspect ratio of the electron-transporting compound particles is 4.5 or less.

[0029] In this specification, unless otherwise specified, the terms "electrophotographic photoreceptor relating to this disclosure" or "photoreceptor relating to this disclosure" refer to both the first embodiment and the second embodiment described above.

[0030] Figure 1 schematically shows an example of the layer configuration of an electrophotographic photoreceptor according to this embodiment. The photoreceptor 7A shown in Figure 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 support 4. The charge generation layer 2 and the charge transport layer 3 constitute the photosensitive layer 5. The photoreceptor 7A may also have a layer configuration in which a protective layer is further provided on the charge transport layer 3.

[0031] In the electrophotographic photoreceptor according to this embodiment, the photosensitive layer may be a stacked photosensitive layer in which the charge generation layer 2 and the charge transport layer 3 are separated, as shown in the photoreceptor 7A in Figure 1, or it may be a single-layer photosensitive layer that has charge generation and charge transport capabilities instead of the charge generation layer 2 and the charge transport layer 3.

[0032] It was found that the underlayer, in which crystalline electron-transporting compound particles are dispersed, exhibits good electron transport properties due to the π-π interactions between molecules in the crystal of the electron-transporting compound. However, because π-π interactions have a relatively strong bonding force compared to other intermolecular interactions, anisotropy occurs in the bonding force, making it easy for crystal grains to take on needle-like or flaky shapes, and due to the shape of the crystal grains, the particles become oriented within the film. This orientation is unfavorable for sensitivity, and also makes it easier for particles to come into contact with each other, thus easily forming leak points. In the electrophotographic photoreceptor according to this embodiment, when the full width at half maximum of the maximum intensity peak in the X-ray diffraction measurement of the undercoat layer measured from the thickness direction is 5° or less, and the relative integrated intensity of each peak in the X-ray diffraction measurement of the undercoat layer measured from the thickness direction is taken as I1, and the relative integrated intensity of each peak in the X-ray diffraction measurement of the undercoat layer measured in a powder state with a volume average particle size of 5 μm or less is taken as I2, then the value of the maximum value Nmax in the orientation index N represented by formula (1) is 1 or more and 3 or less, or the average aspect ratio of the electron-transporting compound particles is 4.5 or less, the electron-transporting compound particles in the undercoat layer have few aggregates and are randomly dispersed, thereby obtaining an electrophotographic photoreceptor with excellent chargeability and charge transportability.

[0033] The following describes in detail each layer of the photoreceptor according to this embodiment.

[0034] [Sublayer] The electrophotographic photoreceptor according to this disclosure has an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer contains crystalline electron-transporting compound particles. The electron-transporting compound particles only need to have crystal diffraction peaks (also simply called "peaks") in X-ray diffraction measurements, and may be single crystal particles or particles formed by the aggregation of two or more crystal particles. In this embodiment, the "maximum intensity peak" is the strongest crystal diffraction peak, and the "full width at half maximum of the maximum intensity peak" represents the width of the peak in the 2θ direction at an intensity value intermediate between the peak top intensity value of the maximum intensity peak and the background intensity value. Furthermore, in this embodiment, the relative integrated intensity of the peak in the X-ray diffraction measurement is obtained by integrating the value obtained by subtracting the background intensity from the peak intensity, and the subtraction of the background intensity is performed by the Shirley method. The orientation index N at a certain peak A, expressed by equation (1), is the value obtained by dividing the ratio of the relative integrated intensity of a certain peak A in an X-ray diffraction measurement to the relative integrated intensity of all peaks, by the ratio of the relative integrated intensity of a certain peak A in an X-ray diffraction measurement performed with the undercoat in a powder state with a volume-average particle size of 5 μm or less, to the ratio of the relative integrated intensity of all peaks in an X-ray diffraction measurement performed with the undercoat in a powder state with a volume-average particle size of 5 μm or less. The largest of the orientation indices N expressed by equation (1) obtained at each peak is the value of Nmax. Furthermore, when the base layer is in a powder state with a volume-average particle size of 5 μm or less, it is presumed that the orientation state is random. Therefore, the smaller the value of the maximum value Nmax in the orientation index N expressed in equation (1), the less crystal orientation there is in the base layer, and the more random the arrangement of the crystal orientation of the electron-transporting compound particles in the base layer is presumed to be.

[0035] In the first embodiment of the electrophotographic photoreceptor according to this embodiment, the full width at half maximum of the maximum intensity peak measured in X-ray diffraction of the undercoat layer from the thickness direction is 5° or less, preferably 3° or less, more preferably 1.0° or less, and particularly preferably 0.7° or less, from the viewpoint of chargeability and electron transportability. In the second embodiment of the electrophotographic photoreceptor according to this embodiment, the full width at half maximum of the maximum intensity peak in the X-ray diffraction measurement of the undercoat layer measured from the thickness direction is preferably 5° or less, more preferably 3° or less, even more preferably 1.0° or less, and particularly preferably 0.7° or less, from the viewpoint of chargeability and electron transportability.

[0036] In the first embodiment of the electrophotographic photoreceptor according to this embodiment, when I1 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer measured from the thickness direction, and I2 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer in a powder state with a volume-average particle size of 5 μm or less, the maximum value Nmax in the orientation index N represented by formula (1) is 1 or more and 3 or less, preferably 1 or more and 2.7 or less, and more preferably 1 or more and 2.5 or less, from the viewpoint of chargeability and electron transportability. In the second embodiment of the electrophotographic photoreceptor according to this embodiment, when I1 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer measured from the thickness direction, and I2 is the relative integrated intensity of each peak in an X-ray diffraction measurement of the undercoat layer in a powder state with a volume-average particle size of 5 μm or less, the value of the maximum value Nmax in the orientation index N represented by formula (1) is preferably 1 or more and 3 or less, more preferably 1 or more and 2.7 or less, and even more preferably 1 or more and 2.5 or less, from the viewpoint of chargeability and electron transportability.

[0037] In this embodiment, the full width at half maximum of the maximum intensity peak and the maximum value Nmax among the orientation index N are determined by X-ray diffraction measurement. Specifically, the measurement is performed under the following conditions. Measurement device: Bruker AX Corporation, D8DISCOVER X-ray source:CuKα Measurement method: 2θ / θ scan However, Cr, Fe, Co, and Mo may also be used as X-ray sources, and the measurement range must be set to a range in which all diffraction peaks originating from electron-transporting compounds in powder form can be detected.

[0038] Furthermore, any method can be used to obtain a powder with a volume-average particle size of 5 μm or less from the lower layer, including grinding using a ball mill, bead mill, mortar and pestle, sand mill, kneader, attritor, etc., or by dissolving in fluoroacetic acid, sulfuric acid, etc., and then contacting it with water or a poor solvent to precipitate microcrystals. In addition, the above grinding treatment can be performed using either a dry or wet method. It is preferable to use inorganic compounds such as sodium chloride and sodium sulfate, or grinding media such as glass beads, steel beads, alumina beads, and zirconia beads during grinding, as this makes it easier to obtain crystalline uniformity. In the case of a wet method, any treatment solvent such as water, alcohol, or organic solvent can be used to further control the crystalline shape and size of the particles.

[0039] <<Electron transport compound particles>> The aforementioned underlayer contains crystalline electron-transporting compound particles. In the second embodiment of the electrophotographic photoreceptor according to this embodiment, the average aspect ratio of the electron-transporting compound particles is 4.5 or less, preferably 3.0 or less, more preferably 2.0 or less, and particularly preferably 1.0 or more and 1.5 or less, from the viewpoint of chargeability and electron transportability. In the second embodiment of the electrophotographic photoreceptor according to this embodiment, the average aspect ratio of the electron-transporting compound particles is preferably 4.5 or less, more preferably 3.0 or less, even more preferably 2.0 or less, and particularly preferably 1.0 or more and 1.5 or less, from the viewpoint of chargeability and electron transportability.

[0040] In this embodiment, the average aspect ratio of the electron-transporting compound particles is measured directly from the results of observations made using a field emission scanning electron microscope (JEOL JSM-6700F) at magnification of 3,000 to 100,000 times. The major and minor axes are measured for 100 particles, the aspect ratio (major axis / minor axis) is calculated, and the average of these aspect ratios for 100 particles is taken as the average aspect ratio.

[0041] The electron transporting compound in the electron transporting compound particles may be, from the viewpoints of chargeability and electron transporting property, for example, perinone compounds; naphthalenediimide compounds; perylenediimide compounds; quinone compounds such as p-benzoquinone, chloranil, bromanil, anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; dinaphthoquinone compounds; diphenoquinone compounds; xanthone compounds; benzophenone compounds; cyanovinyl compounds; ethylene compounds and other electron transporting compounds. The electron transporting material may be used alone or in combination of two or more, but it is preferably used alone. Among them, the electron transporting compound in the electron transporting compound particles is preferably a naphthalenediimide compound or a perylenediimide compound from the viewpoints of chargeability and electron transporting property, more preferably a naphthalenetetracarboxylic diimide compound or a perylenetetracarboxylic diimide compound, and particularly preferably a perylenetetracarboxylic diimide compound.

[0042] Also, from the viewpoints of chargeability and electron transporting property, the electron transporting compound particles are preferably particles of a compound represented by any of the following formulas (P1) to (P8), more preferably particles of a compound represented by any of the following formulas (P1) to (P4), and particularly preferably particles of a compound represented by the following formula (P4). In the above aspect, it has excellent chargeability, excellent dispersibility in the underlayer, and small compositional deviation, so it has excellent electron transporting property.

[0043]

Chemical formula

[0044] [[ID=1十八]]In formula (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18each 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, R 11 and R 12 、R 12 and R 13 and R 13 and R 14 each independently may be linked to each other to form a ring, R 15 and R 16 、R 16 and R 17 and R 17 and R 18 each independently may be linked to each other to form a ring. In formula (P2), R 21 、R 22 、R 23 H、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, 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 each independently may be linked to each other to form a ring, R 25 and R 26 、R 26 and R 27 and R 27 and R 28 each independently may be linked to each other to form a ring. In formula (P3), R 31 、R 32 、R 33 、R 34 、R 35 and R 36Each of these 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 formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 Each of these 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 formula (P5), R 51 , R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 Each of these 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 formula (P6), R 61 , R 62 , R 63 and R 64 Each of these 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 formula (P7), R 71 , R 72 , R 73 , R 74 , R 75 , R 76 , R 77 and R 78 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2). In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 and R87 Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0045] - Compounds represented by formula (P1) or formula (P2) - The compounds represented by formula (P1) or formula (P2) will be described below.

[0046] [ka]

[0047] In formula (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 (Hereafter simply "R 11 ~R 18 It is also called ). Each of these 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 These elements may be connected to each other independently to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 These elements may be connected to each other independently to form a ring. In formula (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R28 (Hereafter simply "R 21 ~R 28 It is also called ). Each of these 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 These elements may be connected to each other independently to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 These elements may be connected to each other independently to form a ring. In formula (P1), R 11 ~R 18 Examples of alkyl groups represented by include substituted or unsubstituted alkyl groups.

[0048] In formula (P1), R 11 ~R 18 Examples of unsubstituted alkyl groups represented by include linear alkyl groups having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), branched alkyl groups having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and cyclic alkyl groups having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0049] Examples of linear alkyl groups having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, tridecyl group, n-tetradecyl group, n-pentadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group.

[0050] Examples of branched alkyl groups having 3 to 20 carbon atoms include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, tert-tetradecyl group, and tert-pentadecyl group.

[0051] Examples of cyclic alkyl groups having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl groups, as well as polycyclic alkyl groups (e.g., bicyclic, tricyclic, spirocyclic) formed by linking these monocyclic alkyl groups.

[0052] Among the above, linear alkyl groups such as methyl groups and ethyl groups are preferred as unsubstituted alkyl groups.

[0053] Substituents in alkyl groups include alkoxy groups, hydroxyl groups, carboxyl groups, nitro groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an alkoxy group that substitutes a hydrogen atom in an alkyl group, R in formula (P1) 11 ~R 18 Examples of groups similar to the unsubstituted alkoxy group represented by include:

[0054] In formula (P1), R 11 ~R 18 Examples of alkoxy groups represented by include substituted or unsubstituted alkoxy groups.

[0055] In formula (P1), R 11 ~R 18Examples of unsubstituted alkoxy groups represented by include linear, branched, or cyclic alkoxy groups having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms).

[0056] Specific examples of linear alkoxy groups include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, and n-decyloxy groups. Examples of branched alkoxy groups include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, tert-hexyloxy group, isoheptyloxy group, sec-heptyloxy group, tert-heptyloxy group, isooctyloxy group, sec-octyloxy group, tert-octyloxy group, isononyloxy group, sec-nonyloxy group, tert-nonyloxy group, isodecyloxy group, sec-decyloxy group, and tert-decyloxy group. Examples of cyclic alkoxy groups include cyclopropoxy, cyclobutoxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, cyclooctyloxy, cyclononyloxy, and cyclodecyloxy groups. Among these, linear alkoxy groups are preferred as unsubstituted alkoxy groups.

[0057] Substituents in alkoxy groups include aryl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, hydroxyl groups, carboxyl groups, nitro groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an aryl group that substitutes a hydrogen atom in an alkoxy group, in formula (P1), R 11 ~R 18 Examples include unsubstituted aryl groups represented by . Examples of the alkoxycarbonyl group that substitutes the hydrogen atom in the alkoxy group include, in formula (P1), R 11 ~R 18 and groups similar to the unsubstituted alkoxycarbonyl group represented thereby. Examples of the aryloxycarbonyl group that substitutes the hydrogen atom in the alkoxy group include, in formula (P1), R 11 ~R 18 and groups similar to the unsubstituted aryloxycarbonyl group represented thereby.

[0058] In formula (P1), examples of the aralkyl group represented by R 11 ~R 18 include substituted or unsubstituted aralkyl groups.

[0059] In formula (P1), the unsubstituted aralkyl group represented by R 11 ~R 18 is preferably an aralkyl group having 7 to 30 carbon atoms, more preferably an aralkyl group having 7 to 16 carbon atoms, and still more preferably an aralkyl group having 7 to 12 carbon atoms.

[0060] Examples of the unsubstituted aralkyl group having 7 to 30 carbon atoms include benzyl group, phenylethyl group, phenylpropyl group, 4-phenylbutyl group, phenylpentyl group, phenylhexyl group, phenylheptyl group, phenyloctyl group, phenylnonyl group, naphthylmethyl group, naphthylethyl group, anthracylmethyl group, phenyl-cyclopentylmethyl group, and the like.

[0061] Examples of the substituent 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, an iodine atom, etc.). Examples of the alkoxy group that substitutes the hydrogen atom in the aralkyl group include, in formula (P1), R 11 ~R 18 and groups similar to the unsubstituted alkoxy group represented thereby. Examples of the alkoxycarbonyl group that substitutes the hydrogen atom in the aralkyl group include, in formula (P1), R11 ~R 18 Examples of the group similar to the unsubstituted alkoxycarbonyl group represented by it include. As the aryloxycarbonyl group that substitutes the hydrogen atom in the aralkyl group, in formula (P1), R 11 ~R 18 Examples of the group similar to the unsubstituted aryloxycarbonyl group represented by it include.

[0062] In formula (P1), R 11 ~R 18 Examples of the aryl group represented by it include substituted or unsubstituted aryl groups.

[0063] In formula (P1), R 11 ~R 18 Examples of the unsubstituted aryl group represented by it preferably include an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and still more preferably an aryl group having 6 to 10 carbon atoms.

[0064] Examples of the aryl group having 6 to 30 carbon atoms include phenyl group, biphenyl group, 1-naphthyl group, 2-naphthyl group, 9-anthryl group, 9-phenanthryl group, 1-pyrenyl group, 5-naphthacenyl group, 1-indenyl group, 2-azulenyl group, 9-fluorenyl group, biphenylene group, indacenyl group, fluoranthenyl group, acenaphthylenyl group, aceanthrylenyl group, phenalenyl group, fluorenyl group, anthryl group, bianthracenyl group, teranthracenyl group, quarteranthracenyl group, anthraquinolyl group, phenanthryl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, preiadrenyl group, picenyl group, perylenyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexaphenyl group, hexacenyl group, rubicenyl group, coronenyl group, etc. Among the above, a phenyl group is preferable.

[0065] Examples of the substituent in the aryl group include an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (fluorine atom, bromine atom, iodine atom, etc.). As the alkyl group that substitutes the hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include . As an alkoxy group that substitutes a hydrogen atom in an aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxy group represented by include: As for the alkoxycarbonyl group that substitutes a hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As an aryloxycarbonyl group that substitutes a hydrogen atom in the aryl group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0066] In formula (P1), R 11 ~R 18 Examples of aryloxy groups represented by -O-Ar (where Ar represents an aryl group) include substituted and unsubstituted aryloxy groups.

[0067] In formula (P1), R 11 ~R 18 The unsubstituted aryloxy group represented by 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.

[0068] Aryloxy groups with 6 to 30 carbon atoms include phenyloxy group (phenoxy group), biphenyloxy group, 1-naphthyloxy group, 2-naphthyloxy group, 9-anthryloxy group, 9-phenanthryloxy group, 1-pyrenyloxy group, 5-naphthacenyloxy group, 1-indenyloxy group, 2-azlenyloxy group, 9-fluorenyloxy group, biphenylenyloxy group, indacenyloxy group, fluoranthenyloxy group, acenaphthyleneyloxy group, aceanthrlenyloxy group, phenalenyloxy group, and fluorenyloxy group. Examples include the phenyloxy group, anthryloxy group, bianthrencenyloxy group, teranthrencenyloxy group, quarteranthrencenyloxy group, anthraquinolyloxy group, phenanthryloxy group, triphenylenyloxy group, pyrenyloxy group, crisenyloxy group, naphthacenyloxy group, pleiadenyloxy group, picenyloxy group, perilennyloxy group, pentaphenyloxy group, pentacenyloxy group, tetraphenylenyloxy group, hexaphenyloxy group, hexacenyloxy group, rubicenyloxy group, coronenyloxy group, etc. Among the above, the phenyloxy group (phenoxy group) is preferred.

[0069] Substituents in the aryloxy group include alkyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As the alkyl group that substitutes the hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include . As for the alkoxycarbonyl group that substitutes the hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted alkoxycarbonyl group represented by include . As an aryloxycarbonyl group that substitutes a hydrogen atom in the aryloxy group, in formula (P1), R 11 ~R 18 Examples of groups similar to the unsubstituted aryloxycarbonyl group represented by include .

[0070] In formula (P1), R 11 ~R 18 Examples of alkoxycarbonyl groups represented by (-CO-OR, where R represents an alkyl group) include substituted or unsubstituted alkoxycarbonyl groups.

[0071] In formula (P1), R 11 ~R 18 The number of carbon atoms in the alkyl chain of the unsubstituted alkoxycarbonyl group represented by is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 10.

[0072] Examples of alkoxycarbonyl groups with 1 to 20 carbon atoms in the alkyl chain include methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, sec-butoxybutylcarbonyl group, tert-butoxycarbonyl group, pentaoxycarbonyl group, hexaoxycarbonyl group, heptaoxycarbonyl group, octaoxycarbonyl group, nonaoxycarbonyl group, decaoxycarbonyl group, dodecaoxycarbonyl group, tridecaoxycarbonyl group, tetradecaoxycarbonyl group, pentadecaoxycarbonyl group, hexadecaoxycarbonyl group, heptadecaoxycarbonyl group, octadecaoxycarbonyl group, nonadecaoxycarbonyl group, and eicosaoxycarbonyl group.

[0073] Examples of substituents on an alkoxycarbonyl group include aryl groups, hydroxyl groups, and halogen atoms (fluorine atoms, bromine atoms, iodine atoms, etc.). As an aryl group that substitutes a hydrogen atom in an alkoxycarbonyl group, in formula (P1), R 11 ~R 18 Examples include unsubstituted aryl groups represented by .

[0074] In formula (P1), R 11 ~R 18Examples of aryloxycarbonyl groups represented by -CO-OAr (where Ar represents an aryl group) include substituted and unsubstituted aryloxycarbonyl groups.

[0075] In formula (P1), R 11 ~R 18 In the unsubstituted aryloxycarbonyl group represented by , the number of carbon atoms in the aryl group is preferably 6 to 30, more preferably 6 to 14, and even more preferably 6 to 10.

[0076] Examples of aryloxycarbonyl groups having aryl groups with 6 to 30 carbon atoms include phenoxycarbonyl group, biphenyloxycarbonyl group, 1-naphthyloxycarbonyl group, 2-naphthyloxycarbonyl group, 9-anthuryloxycarbonyl group, 9-phenanthryloxycarbonyl group, 1-pyrenyloxycarbonyl group, 5-naphthacenyloxycarbonyl group, 1-indenyloxycarbonyl group, 2-azlenyloxycarbonyl group, 9-fluorenyloxycarbonyl group, biphenylenyloxycarbonyl group, indacenyloxycarbonyl group, fluoranthenyloxycarbonyl group, acenaphthyleneyloxycarbonyl group, aceanthryleneyloxycarbonyl group, phenalenyloxycarbonyl group, fluorenyloxycarbonyl group, Examples include anthryloxycarbonyl group, biantracenyloxycarbonyl group, terantracenyloxycarbonyl group, quarterantracenyloxycarbonyl group, anthraquinolyloxycarbonyl group, phenanthryloxycarbonyl group, triphenylenyloxycarbonyl group, pyrenyloxycarbonyl group, chrysenyloxycarbonyl group, naphthacenyloxycarbonyl group, pleiadenyloxycarbonyl group, picenyloxycarbonyl group, perilennyloxycarbonyl group, pentaphenyloxycarbonyl group, pentacenyloxycarbonyl group, tetraphenylenyloxycarbonyl group, hexaphenyloxycarbonyl group, hexacenyloxycarbonyl group, rubicenyloxycarbonyl group, coronenyloxycarbonyl group, etc. Among the above, the phenoxycarbonyl group is preferred.

[0077] Examples of the substituent in the aryloxycarbonyl group include an alkyl group, a hydroxy group, and a halogen atom (such as a fluorine atom, a bromine atom, an iodine atom, etc.). Examples of the alkyl group that substitutes the hydrogen atom of the aryloxycarbonyl group include, in formula (P1), R 11 ~R 18 and groups similar to the unsubstituted alkyl group represented thereby.

[0078] In formula (P1), examples of the alkoxycarbonylalkyl group (-(C 11 ~R 18 H n )-CO-OR, where R represents an alkyl group and n represents an integer of 1 or more.) include substituted or unsubstituted alkoxycarbonylalkyl groups. 2n )-CO-OR, where R represents an alkyl group and n represents an integer of 1 or more.) include substituted or unsubstituted alkoxycarbonylalkyl groups.

[0079] In formula (P1), examples of the alkoxycarbonyl group (-CO-OR) in the unsubstituted alkoxycarbonylalkyl group represented by R 11 ~R 18 include groups similar to the alkoxycarbonyl group represented by R 11 ~R 18 in formula (P1).

[0080] In formula (P1), examples of the alkylene chain (-(C 11 ~R 18 H n ) in the unsubstituted alkoxycarbonylalkyl group represented by R 2n -) include 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).

[0081] Examples of linear alkylene chains having 1 to 20 carbon atoms include methylene group, ethylene group, n-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, n-octylene group, n-nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, tridecylene group, n-tetradecylene group, n-pentadecylene group, n-heptadecylene group, n-octadecylene group, n-nonadesilene group, and n-icosilene group.

[0082] Examples of branched alkylene chains having 3 to 20 carbon atoms include isopropylene group, isobutylene group, sec-butylene group, tert-butylene group, isopentylene group, neopentylene group, tert-pentylene group, isohexylene group, sec-hexylene group, tert-hexylene group, isoheptylene group, sec-heptylene group, tert-heptylene group, isooctylene group, sec-octylene group, tert-octylene group, isononylene group, sec-nonylene group, tert-nonylene group, isodecylene group, sec-decylene group, tert-decylene group, isododecylene group, sec-dodecylene group, tert-dodecylene group, tert-tetradecylene group, tert-pentadecylene group, and the like.

[0083] Examples of cyclic alkylene chains having 3 to 20 carbon atoms include cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, cyclononylene, and cyclodecylene groups.

[0084] Examples of substituents in alkoxycarbonylalkyl groups include aryl groups, hydroxyl groups, and halogen atoms (such as fluorine, bromine, and iodine atoms). As an aryl group that substitutes a hydrogen atom in an alkoxycarbonylalkyl group, in formula (P1), R 11 ~R 18 Examples include unsubstituted aryl groups represented by .

[0085] In formula (P1), R 11 ~R 18(-(C) n H 2n )-CO-OAr, where Ar represents an aryl group and n represents an integer of 1 or more.) Examples include substituted or unsubstituted aryloxycarbonylalkyl groups.

[0086] In formula (P1), R 11 ~R 18 In the unsubstituted aryloxycarbonylalkyl group represented by (P1), the aryloxycarbonyl group (-CO-OAr, where Ar represents an aryl group) is R 11 ~R 18 Examples of groups similar to the aryloxycarbonyl group represented by [the symbol] include [the symbol].

[0087] In formula (P1), R 11 ~R 18 Alkylene chain (-C) in unsubstituted aryloxycarbonylalkyl groups represented by n H 2n -) In equation (P1), R 11 ~R 18 Examples of groups similar to the alkylene chain in the alkoxycarbonylalkyl group represented by include .

[0088] Substituents in aryloxycarbonylalkyl groups include alkyl groups, hydroxyl groups, and halogen atoms (such as fluorine, bromine, and iodine atoms). As the alkyl group that substitutes the hydrogen atom of the aryloxycarbonylalkyl group, in formula (P1), R 11 ~R 18 Examples of groups similar to unsubstituted alkyl groups represented by include .

[0089] In formula (P1), R 11 ~R 18 Examples of halogen atoms represented by this formula include fluorine, chlorine, bromine, and iodine atoms.

[0090] In formula (P1), R 11 ~R 14 Two or more of the following, or R15 ~R 18 The ring structure formed by the linkage of two or more of these elements may be an aliphatic hydrocarbon ring structure, a heterocyclic ring structure, an aromatic hydrocarbon ring structure, or a heteroaromatic ring structure, but an aromatic hydrocarbon ring structure is preferred. Among these, preferred ring structures include benzene rings, condensed rings having 10 to 18 carbon atoms (naphthalene rings, anthracene rings, phenanthrene rings, chrysene rings (benzo[α]phenanthrene rings), tetracene rings, tetrafen rings (benzo[α]anthracene rings), triphenylene rings, etc.), with benzene rings being particularly preferred.

[0091] In formula (P2), R 21 ~R 28 The alkyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to the alkyl groups represented are shown. In formula (P2), R 21 ~R 28 The alkoxy group represented by formula (P1) is R 11 ~R 18 Examples of groups similar to the alkoxy group represented by can be cited. In formula (P2), R 21 ~R 28 The aralkyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to the aralkyl group represented by this symbol include: In formula (P2), R 21 ~R 28 As an aryl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the aryl group represented by include . In formula (P2), R 21 ~R 28 The aryloxy group represented by is, in formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxy group represented by can be cited. In formula (P2), R 21 ~R 28The alkoxycarbonyl group represented by formula (P1) is R 11 ~R 18 Examples of groups similar to the alkoxycarbonyl group represented by include . In formula (P2), R 21 ~R 28 The aryloxycarbonyl group represented by is, in formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxycarbonyl group represented by [the symbol] include [the symbol]. In formula (P2), R 21 ~R 28 As an alkoxycarbonylalkyl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the alkoxycarbonylalkyl groups represented by include . In formula (P2), R 21 ~R 28 As an aryloxycarbonylalkyl group represented by formula (P1), R 11 ~R 18 Examples of groups similar to the aryloxycarbonylalkyl group represented by [the formula shown] include [the formula shown]. In formula (P2), R 21 ~R 28 As for halogen atoms represented by formula (P1), R 11 ~R 18 Examples of atoms similar to halogen atoms represented by [the symbol] include [the symbol].

[0092] In formula (P2), 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 28However, examples of ring structures formed by the linking of these rings include benzene rings and condensed rings having 10 to 18 carbon atoms (naphthalene rings, anthracene rings, phenanthrene rings, chrysene rings (benzo[α]phenanthrene rings), tetracene rings, tetrafen rings (benzo[α]anthracene rings), triphenylene rings, etc.). Among the above, benzene rings are preferred as the ring structure formed.

[0093] In equation (P1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 Each of these is preferably independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group.

[0094] In equation (P2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 Each of these is preferably independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group.

[0095] The following are specific examples of compounds represented by formula (P1) or formula (P2), but this embodiment is not limited to these. Note that Ph represents a phenyl group.

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] The compound represented by formula (P1) and the compound represented by formula (P2) are isomers (i.e., cis and trans isomers). A common synthesis method involves heating and condensing 2 moles of orthophenylenediamine compound and 1 mole of naphthalenetetracarboxylic acid compound, yielding a mixture of cis and trans isomers, with the cis isomer usually being more abundant than the trans isomer. The cis and trans isomers can be separated, for example, by heating and washing with a potassium hydroxide alcohol solution, which separates the soluble cis isomer from the sparingly soluble trans isomer.

[0103] - Compound represented by formula (P3) - The compound represented by formula (P3) will be explained below.

[0104] [ka]

[0105] In formula (P3), R 31 , R 32 , R 33 , R 34 , R 35 and R 36 (Hereafter simply "R 31 ~R 36It is also called ). Each of these 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 formula (P3), R 31 ~R 36 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0106] The following are example compounds of the compound represented by formula (P3), but this embodiment is not limited to these. The example compound numbers below will be denoted as example compound (3-number), etc. Specifically, for example, example compound 5 below will be denoted as "example compound (3-5)," etc. The same applies to each formula below.

[0107] [ka]

[0108] The abbreviations and symbols in the above example compounds have the following meanings. • Pr: n-propyl group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • p-Cl-C6H4: parachlorophenyl group • C6H5CH2: Benzyl group • C6H5CH2CH2: Phenethyl group

[0109] - Compound represented by formula (P4) - The compound represented by formula (P4) will be described below.

[0110] [ka]

[0111] In formula (P4), R 41 , R 42 , R 43 , R 44 , R 45 , R 46 , R 47 , R 48 , R 49 and R 50 (Hereafter simply "R 51 ~R 50 It is also called ). Each of these 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 formula (P4), R 41 ~R 46 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0112] The following are examples of compounds represented by formula (P4), but this embodiment is not limited to these. The example compound numbers below will be referred to as example compound (3-number). Specifically, for example compound 5 will be referred to as "example compound (3-5)" below.

[0113] [ka]

[0114] The abbreviations and symbols in the above example compounds have the following meanings. •Bu:n-butyl group · c-C6H 11 : Cyclohexyl group • p-CH3-C6H4: paratril group • C6H5: Phenyl group • p-Cl-C6H4: parachlorophenyl group • o-Cl-C6H4: orthochlorophenyl group • C6H5CH2: Benzyl group • 3,5-(CH3)2-C6H4: 3,5-dimethylphenyl group • 3,5-Cl2-C6H4: 3,5-dichlorophenyl group

[0115] - Compound represented by formula (P5) - The compound represented by formula (P5) will be explained below.

[0116] [ka]

[0117] In formula (P5), 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 It is also called ). Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkoxycarbonyl group, or a halogen atom.

[0118] In formula (P5), R 51 ~R 58 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0119] In formula (P5), R 51 ~R 58 Each of these may 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.

[0120] In formula (P5), R 51 and R 58Each of these groups is independently preferred from the viewpoint of electron transport properties to be an alkyl group having 3 to 12 carbon atoms, an alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having 3 to 12 carbon atoms, a branched alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; even more preferably a branched alkyl group having 3 to 8 carbon atoms or a branched alkoxy group having 3 to 8 carbon atoms; and particularly preferred a t-butyl group.

[0121] In formula (P5), R 52 and R 57 Each of these groups is preferably, from the viewpoint of electron transport, 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.

[0122] In formula (P5), R 53 , R 54 , R 55 and R 56 It is preferable that this represents a hydrogen atom. In formula (P5), R 51 and R 58 From the viewpoint of electron transport, it is preferable that these be the same group. In formula (P5), R 52 and R 57 From the viewpoint of electron transport, it is preferable that these be the same group. In formula (P5), R 51 and R 52 From the viewpoint of electron transport, it is preferable that these are different groups. In formula (P5), R 57 and R 58 From the viewpoint of electron transport, it is preferable that these are different groups.

[0123] The following are examples of compounds represented by formula (P5), but this embodiment is not limited to these.

[0124] [ka]

[0125] The abbreviations and symbols in the above example compounds have the following meanings. ·t-C4H9: t-butyl group • CH3O: Methoxy group ·t-C4H9O:t-butoxy group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • C6H5CH2: Benzyl group

[0126] - Compound represented by formula (P6) - The compound represented by formula (P6) will be described below.

[0127] [ka]

[0128] In formula (P6), R 61 , R 62 , R 63 and R 64 (Hereafter simply "R 61 ~R 64 It is also called ). Each of these 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 formula (P6), R 61 ~R 64 The alkyl group, alkoxy group, aralkyl group, aryl group, alkoxycarbonyl group, and halogen atom represented by formula (P1) are R 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0129] In formula (P6), R 61 ~R 64 Each of these may 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.

[0130] In formula (P6), R 61 and R 64 Each of these groups is independently preferred from the viewpoint of electron transport properties to be an alkyl group having 3 to 12 carbon atoms, an alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; more preferably a branched alkyl group having 3 to 12 carbon atoms, a branched alkoxy group having 3 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group; even more preferably a branched alkyl group having 3 to 8 carbon atoms or a branched alkoxy group having 3 to 8 carbon atoms; and particularly preferred a t-butyl group.

[0131] In formula (P6), R 62 and R 64 Each of these groups is preferably, independently from the viewpoint of electron transport, 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.

[0132] In formula (P6), R 61 and R 64 It is preferable that they be the same group. In formula (P6), R 62 and R 63 It is preferable that they be the same group. In formula (P6), R 61 and R 62 These are preferably different groups. In formula (P6), R 63 and R 64 These are preferably different groups.

[0133] The following are examples of compounds represented by formula (P6), but this embodiment is not limited to these.

[0134] [ka]

[0135] The abbreviations and symbols in the above example compounds have the following meanings. ·t-C4H9: t-butyl group • CH3O: Methoxy ·t-C4H9O:t-butoxy group · c-C6H 11 : Cyclohexyl group • C6H5: Phenyl group • C6H5CH2: Benzyl group

[0136] - Compound represented by formula (P7) - The compound represented by formula (P7) will be explained below.

[0137] [ka]

[0138] In formula (P7), 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 It is also called ). Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0139] In formula (P7), R 71 ~R 78Examples of alkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms (preferably 1 to 3 carbon atoms), specifically, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, etc. In formula (P7), R 71 ~R 78 Examples of alkoxy groups include alkoxy groups having 1 to 4 carbon atoms (preferably 1 to 3 carbon atoms), specifically methoxy groups, ethoxy groups, propoxy groups, butoxy groups, and the like.

[0140] In formula (P7), R 71 ~R 78 An example of an aralkyl group represented by -L-Ar is the group denoted as -L-Ar, where L represents an alkylene group and Ar represents an aryl group. Examples of alkylene groups represented by L include linear or branched alkylene groups having 1 to 12 carbon atoms, such as methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, and tert-pentylene group. Examples of aryl groups represented by Ar include phenyl group, methylphenyl group, dimethylphenyl group, and ethylphenyl group. In formula (P7), R 71 ~R 78 Specific examples of the aralkyl group shown include, for example, the benzyl group, methylbenzyl group, dimethylbenzyl group, phenylethyl group, methylphenylethyl group, phenylpropyl group, and phenylbutyl group.

[0141] In formula (P7), R 71 ~R 78 Examples of aryl groups include phenyl, methylphenyl, dimethylphenyl, and ethylphenyl groups. Among these, the phenyl group is preferred.

[0142] In formula (P7), R 71 ~R78 The acyl group shown is (-C(=O)-R AC , the R AC ∫ represents a hydrocarbon group. Examples of such groups include acyl groups having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms), specifically including acetyl groups, propanoyl groups, benzoyl groups, cyclohexanecarbonyl groups, and the like.

[0143] In formula (P7), R 71 ~R 78 The alkoxycarbonyl group represented by is R in formula (P1). 11 ~R 18 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula].

[0144] In formula (P7), R 71 ~R 78 The alkyl, alkoxy, aralkyl, aryl, and alkoxycarbonyl groups shown are R in general formula (1). 11 ~R 18 The alkyl group, alkoxy group, aralkyl group, aryl group, and alkoxycarbonyl group represented by may have substituents similar to those listed above. In formula (P7), R 71 ~R 78 The acyl group represented by is R in formula (P1). 11 ~R 18 The alkyl group represented by may have substituents similar to those listed above.

[0145] In formula (P7), R 71 ~R 78 Examples of halogen atoms represented include fluorine, chlorine, bromine, and iodine atoms.

[0146] In formula (P7), R 78 From the perspective of electron transport, the alkoxycarbonyl group (-C(=O)-OR 78A ) is preferable. 78A This is an alkyl group (long-chain alkyl group) with 8 or more carbon atoms or -L181 -OR 182 This indicates L 181 R indicates an alkylene group, 182 This indicates an alkyl group (long-chain alkyl group) with 8 or more carbon atoms.

[0147] In formula (P7), R 78 -L 181 -OR 182 The group represented by L 181 R indicates an alkylene group, 182 This represents an alkyl group (long-chain alkyl group) with 8 or more carbon atoms.

[0148] L 181 Examples of alkylene groups represented by include linear or branched alkylene groups having 1 to 12 carbon atoms, such as methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, tert-butylene group, n-pentylene group, isopentylene group, neopentylene group, and tert-pentylene group.

[0149] R 182 The long-chain alkyl group represented by is not particularly limited as long as it has 8 or more carbon atoms, but from the viewpoint of suppressing cracking of the photosensitive layer, it is preferable that it has 8 to 12 carbon atoms. Furthermore, the long-chain alkyl group may be linear or branched, but it is preferable that it be linear. Examples of linear alkyl groups having 8 to 12 carbon atoms include n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl groups. 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.

[0150] The compound represented by formula (P7) may have only one long-chain alkyl group in one molecule, or it may have two or more. 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 formula (P7) is preferably 1 to 3, and more preferably 1 to 2.

[0151] In one embodiment, the compound represented by formula (P7) is R from the viewpoint of electron transport. 71 ~R 77 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group, R 78 Compounds exhibiting a linear alkyl group with 8 or fewer carbon atoms are preferred.

[0152] The following are examples of compounds represented by formula (P7), but are not limited to these. The example compound numbers below will be referred to as Example Compound (7-number). Specifically, for example, Example Compound 5 will be referred to as "Example Compound (7-5)".

[0153] [ka]

[0154] The abbreviations and symbols in the above example compounds have the following meanings. ·=C(CN)2: dicyanomethylene group

[0155] - Compound represented by formula (P8) - The compound represented by formula (P8) will be explained below.

[0156] [ka]

[0157] In formula (P8), R 81 , R 82 , R 83 , R 84 , R 85 , R 86 , R 87 and R 88(Hereafter simply "R 81 ~R 88 It is also called ). Each of the following independently represents a hydrogen atom, alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, or halogen atom, and Z represents an oxygen atom or a dicyanomethylene group (=C(CN)2).

[0158] In formula (P8), R 81 ~R 88 The alkyl group, alkoxy group, aralkyl group, aryl group, acyl group, alkoxycarbonyl group, and halogen atom represented by formula (P7) are R 71 ~R 78 Examples of groups similar to alkyl groups, alkoxy groups, aralkyl groups, aryl groups, and alkoxycarbonyl groups represented by [the formula] include [the formula]. In formula (P8), R 81 ~R 88 The acyl group represented by is R in formula (P1). 11 ~R 18 The alkyl group represented by may have substituents similar to those listed above.

[0159] The following are examples of compounds represented by formula (P8), but are not limited to these. The example compound numbers below will be referred to as Example Compound (8-number). Specifically, for example, Example Compound 5 will be referred to as "Example Compound (8-5)".

[0160] [ka]

[0161] The abbreviations and symbols in the above example compounds have the following meanings. • C(=O)CH3: Acetyl group • OCH3: Methoxy group • CN: cyano group • CH2C6H5: benzyl group ·=C(CN)2: dicyanomethylene group

[0162] From the viewpoint of chargeability and electron transportability, the content of the electron-transporting compound particles is preferably 30% to 85% by mass, more preferably 50% to 80% by mass, even more preferably 52% to 75% by mass, and particularly preferably 55% to 70% by mass, based on the total mass of the undercoat.

[0163] -Binding resin- The undercoat preferably contains a binder resin. The type of binder resin included in the base layer is not limited. Examples of binder resins included in the base layer include polyurethane, polyvinyl alcohol resin, polyvinyl acetal resin (including polyvinyl butyral, i.e., butyral resin), casein resin, polyamide resin, cellulose resin, gelatin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, alkyd resin, epoxy resin, etc. The binder resin may be used alone or in combination of two or more types.

[0164] From the viewpoint of further improving the charge retention of the undercoat layer, it is preferable to include polyurethane as the binder resin. When polyurethane is used as the binder resin, the charge retention is superior compared to when other types of binder resins are used. The mechanism for this is thought to be that polyurethane has a high effect (trapping effect) of suppressing the injection of the internal charge (dark carriers) of the electron-transporting compound particles contained in the undercoat layer into the electron-transporting compound particles, so the potential on the surface of the photoreceptor does not easily decrease.

[0165] Polyurethane may also be synthesized by a polyaddition reaction between polyisocyanate and polyol.

[0166] Examples of polyisocyanates include 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, and 3,3'-dimethylene diisocyanate. Examples include diisocyanates such as 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylbiphenylenediisocyanate, 4,4'-biphenylenediisocyanate, dicyclohexylmethane diisocyanate, and methylenebis(4-cyclohexylisocyanate); isocyanurates obtained by trimerizing the diisocyanates; and blocked isocyanates obtained by blocking the isocyanate groups of the diisocyanates with a blocking agent. Among the above, polyisocyanates are preferably polyfunctional, such as isocyanurates having multiple isocyanate groups. One type of polyisocyanate may be used, or two or more types may be used in combination.

[0167] Examples of polyols 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-2,4-pentanediol. Examples of diols include diols such as 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'-dihydroxyphenylsulfone. Examples of polyols include polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols, and polyvinyl butyral. One type of polyol may be used, or two or more types may be used in combination.

[0168] Examples of urethane curing catalysts (i.e., catalysts for the polyaddition reaction between polyisocyanates and polyols) include amine compounds, organic acid metal salts, and organometallic complexes. Examples of amine compounds 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 its salts. Examples of organic acid metal salts or organometallic complexes include dibutyltin laurate, stanus octoate, bismuth octoate, bismuth naphthenate, bismuth salicylate, zinc octoate, zinc naphthenate, and zinc salicylate. Examples of commercially available urethane curing catalysts include the K-KAT series from King Industries, Ltd., such as bismuth carboxylate catalysts like K-KAT348, K-KAT XC-C227, K-KAT XK-628, and K-KAT XK-640; aluminum complex catalysts like K-KAT5218; zirconium complex catalysts like K-KAT4205, K-KAT6212, and K-KATA209; and titanium complex catalysts like TA-30 and TC-750 from Matsumoto Fine Chemicals' Orgatics series.

[0169] When butyral resin is included as the binder resin, the butyral resin content is preferably 0.5% to 20% by mass, and more preferably 1% to 10% by mass, relative to the total mass of the undercoat, from the viewpoint of electrostatic properties and electron transport properties.

[0170] The binder resin contained in the base layer is preferably composed of polyurethane in an amount of 80% to 100% by mass of the total amount of binder resin, more preferably 90% to 100% by mass of polyurethane, and even more preferably 95% to 100% by mass of polyurethane.

[0171] The mass ratio of the total content of the electron-transporting compound particles contained in the undercoat to the content of polyurethane contained in the undercoat is preferably 90:10 to 50:50 for electron-transporting compound particles to polyurethane, and more preferably 80:20 to 70:30.

[0172] <<Inorganic particles>> The undercoat may contain inorganic particles, but from the viewpoint of electrostatic properties, it is preferable that it does not contain them. As for inorganic particles, for example, powder resistance (volume resistivity) 10 2 Ωcm or more 10 11 Examples include inorganic particles smaller than Ωcm. Among these, suitable inorganic particles having the above-mentioned resistance values ​​include 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.

[0173] The specific surface area of ​​inorganic particles using the BET method is, for example, 10 m². 2 A value of 10 m² or more is preferable. 2 When the value is above / g, the decrease in chargeability tends to be suppressed. The volume-average particle size of the inorganic particles is preferably between 50 nm and 2000 nm (preferably between 60 nm and 1000 nm).

[0174] The inorganic particle content is preferably 10% by mass or more and 80% by mass or less relative to the binder resin, and more preferably 40% by mass or more and 80% by mass or less.

[0175] The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or particle sizes may be mixed and used.

[0176] Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0177] 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.

[0178] Silane coupling agents may be used in combination of two or more types. 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-methacrylateoxypropyl-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.

[0179] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0180] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0181] The inorganic particle content is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0182] Here, the lower layer may contain electron-accepting compounds (acceptor compounds) along with inorganic particles.

[0183] Examples of electron-accepting compounds include quinone compounds such as chloranil and bromonil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; as well as other electron-transporting substances. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and specifically, for example, anthraquinone, alizarin, quinizalin, anthralphine, and purpurin are preferred.

[0184] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0185] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0186] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0187] The wet method involves dispersing inorganic particles in a solvent using methods such as stirring, ultrasound, sand milling, attritoring, and ball milling, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed to adhere the electron-accepting compound to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0188] Furthermore, the attachment of the electron-accepting compound may be performed before or after surface treatment with a surface treatment agent on the inorganic particles, or it may be performed simultaneously with the attachment of the electron-accepting compound and surface treatment with the surface treatment agent.

[0189] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0190] <<Additives>> The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include electron-transporting pigments such as polycyclic condensation and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as additives.

[0191] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-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.

[0192] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate 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.

[0193] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-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.

[0194] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0195] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0196] <<Other properties of the lower layer>> The thickness of the undercoat layer is preferably 1 μm or more, and more preferably 3 μm or more. From the viewpoint of superior charge retention, 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.

[0197] The volume resistivity of the lower layer is 1 × 10⁻⁶ 10 Ωcm or more, 1 × 10 12 It is preferable that the density is Ωcm or less.

[0198] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0199] <<Method for forming the lower layer>> There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0200] Solvents for preparing the coating solution for forming the undercoat 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 common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cellsolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. In particular, solvents having at least one hydroxyl group (e.g., alcohols) or ether solvents (e.g., tetrahydrofuran) are preferred.

[0201] Known methods for dispersing electron-transporting compound particles when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers. Since electron-transporting compound particles are poorly soluble in organic solvents, it is desirable to disperse them in organic solvents. Known dispersion methods include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0202] Conventional methods for applying the undercoating solution onto a conductive support include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0203] [Conductive support] Examples of conductive supports 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 supports 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, "conductivity" refers to a volume resistivity of 10 13 This refers to a value less than Ωcm.

[0204] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive support is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. While roughening to prevent interference fringes is not particularly necessary when using non-interfering light as the light source, it is beneficial for extending the lifespan of the conductive support by suppressing the occurrence of defects due to surface irregularities.

[0205] Methods for roughening the surface include, for example, wet honing, which is performed by suspending an abrasive in water and spraying it onto a conductive support; centerless grinding, which is performed by pressing a conductive support against a rotating grinding wheel and continuously grinding it; and anodizing.

[0206] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive support, to form a layer on the surface of the conductive support, and then roughen the surface with the particles dispersed in that layer.

[0207] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive support by using a metal (e.g., aluminum) conductive support as the anode and anodic oxidizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, 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 to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0208] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0209] The conductive support may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0210] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0211] [Middle class] Although not shown in the diagram, 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 resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0212] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0213] There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating are used to form the intermediate layer.

[0214] The thickness of the intermediate layer is preferably set to a range of 0.1 μm to 3 μm, for example. The intermediate layer may also be used as a base layer.

[0215] [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 when using non-coherent light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0216] Examples of charge-generating materials include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthonthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0217] Among these, in order to accommodate 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, and titanyl phthalocyanine are more preferable.

[0218] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthoten; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0219] Even when using non-coherent light sources such as LEDs and organic EL image arrays with a central emission wavelength between 450 nm and 780 nm, the above charge generating materials may be used. However, from the viewpoint of resolution, when using a thin film of 20 μm or less for the photosensitive layer, the electric field strength in the photosensitive layer increases, making it easier to cause a decrease in charge due to charge injection from the conductive support, resulting in image defects known as black spots. This is particularly noticeable when using charge generating materials that are p-type semiconductors that easily generate dark current, such as trigonal selenium and phthalocyanine pigments.

[0220] In contrast, when n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark currents are less likely to occur, and image defects called black spots can be suppressed even in thin films. Furthermore, the n-type is determined using the commonly used time-of-flight method, based on the polarity of the photocurrent that flows. Those that are more likely to carry electrons as carriers than holes are classified as n-type.

[0221] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may 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 (polycondensate of bisphenols and aromatic divalent carboxylic 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, and polyvinylpyrrolidone resin. Here, "insulating properties" refers to a volume resistivity of 10 13 This refers to a value of Ωcm or greater. These binder resins can be used individually or in combination of two or more types.

[0222] Furthermore, the mixing ratio of the charge-generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass ratio.

[0223] The charge generation layer may also contain other well-known additives.

[0224] The formation of the charge generation layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge generation layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused aromatic pigments or perylene pigments as the charge generation material.

[0225] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cellsolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0226] Methods for dispersing particles (e.g., charge-generating materials) in a coating solution for forming a charge-generating layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, which disperse the dispersion by causing liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, which disperse the dispersion by penetrating fine channels under high pressure. Furthermore, during this dispersion, it is effective to set the average particle size of the charge-generating material in the coating solution 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.

[0227] Conventional methods for applying the charge-generating layer forming coating solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0228] The thickness of the charge generation layer is preferably set to a range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0229] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0230] Examples of charge transport materials include 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, which are electron transport compounds. Other 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 individually or in combination of two or more, but are not limited to these uses.

[0231] As charge transport materials, from the viewpoint of charge mobility, the triarylamine derivative shown in the following structural formula (a-1) and the benzidine derivative shown in the following structural formula (a-2) are preferred.

[0232] [ka]

[0233] In structural formula (a-1), Ar T1 Ar T2 , and Ar T3 Each is 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 , RT5 , R T6 , R T7 , and R T8 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0234] [ka]

[0235] In structural formula (a-2), R T91 and R T92 Each of these 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 of these independently consists of 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, and -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) shows R T12 , R T13 , R T14 , R T15 and R T16 Each of these 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 between 0 and 2. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0236] Here, among the triarylamine derivative represented by structural formula (a-1) and the benzidine derivative represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0237] As polymer charge transport materials, known charge transport materials such as poly-N-vinylcarbazole and polysilane can be used. Polyester-based polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone, or it may be used in combination with a binder resin.

[0238] Examples of binder resins used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, and polysilane. Among these, polycarbonate resin or polyarylate resin is preferred as the binder resin. These binder resins can be used individually or in combination of two or more. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0239] The charge transport layer may also contain other well-known additives.

[0240] The formation of the charge transport layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0241] Suitable solvents for preparing the coating solution for forming the charge transport layer include common organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents can be used individually or in mixtures of two or more.

[0242] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0243] The thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0244] [Protective layer] A protective layer is provided on the photosensitive layer as needed. The protective layer is provided, 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 protective layer composed of a cured film (crosslinked film). Examples of such layers include those shown in 1) or 2) below.

[0245] 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 within the same molecule (i.e., a layer containing a polymer or crosslinked form of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material containing reactive groups that does not have a charge transport skeleton but has reactive groups (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked form of the non-charge transport material containing reactive groups).

[0246] The reactive groups in the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [where R represents an alkyl group], -NH2, -SH, -COOH, and -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 R represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group. Q2 Examples of well-known reactive groups include hydrogen atoms, alkyl groups, and trialkylsilyl groups. Qn represents an integer from 1 to 3.

[0247] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, for example, a functional group having at least one carbon double bond. Specifically, examples include groups containing at least one selected from vinyl groups, vinyl ether groups, vinyl thioether groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives. Among these, the chain polymerizable group is preferably a group containing at least one selected from vinyl groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives, due to its excellent reactivity.

[0248] The charge-transporting skeleton of the reactive group-containing charge-transporting material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors. Examples include skeletons derived from nitrogen-containing hole-transporting compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, in which the nitrogen atom is conjugated. Among these, the triarylamine skeleton is preferred.

[0249] These reactive groups and charge-transporting skeletons, including reactive group-containing charge transport materials, non-reactive charge transport materials, and reactive group-containing non-charge transport materials, can be selected from well-known materials.

[0250] The protective layer may also contain other well-known additives.

[0251] There are no particular restrictions on the formation of the protective layer, and well-known formation methods can be used. For example, it can be formed by adding the above components to a solvent to create a protective layer coating solution, drying the coating, and then performing a curing treatment such as heating as necessary.

[0252] Solvents for preparing coating solutions for forming a 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 can be used individually or in combination of two or more. Furthermore, the coating solution for forming the protective layer may be a solvent-free coating solution.

[0253] Conventional methods for applying a protective layer-forming coating solution onto a photosensitive layer (e.g., a charge transport layer) include immersion coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0254] The thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, and more preferably within the range of 2 μm to 10 μm.

[0255] [Single-layer photosensitive layer] A single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer comprising a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. Furthermore, the content of the charge-generating material in the single-layer photosensitive layer is preferably 0.1% to 10% by mass, and more preferably 0.8% to 5% by mass, relative to the total mass. In addition, the content of the charge-transporting material in the single-layer photosensitive layer is preferably 5% to 50% by mass, relative to the total mass. The method for forming a single-layer photosensitive layer is the same as the method for forming a charge generation layer or a charge transport layer. The thickness of the single-layer photosensitive layer is, for example, preferably 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[0256] (Image forming apparatus and process cartridges) The image forming apparatus according to this embodiment comprises an electrophotographic photoreceptor, a charging means for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer means for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to this embodiment is used as the electrophotographic photoreceptor.

[0257] The image forming apparatus according to this embodiment includes a fixing means for fixing a toner image transferred to the surface of a recording medium; a direct transfer method apparatus for directly transferring a toner image formed on the surface of an electrophotographic photoreceptor to a recording medium; an intermediate transfer method apparatus for first transferring a toner image formed on the surface of an electrophotographic photoreceptor to the surface of an intermediate transfer body, and secondarily transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a cleaning means for cleaning the surface of the electrophotographic photoreceptor after the transfer of the toner image and before it is charged; a static elimination means for irradiating the surface of the electrophotographic photoreceptor with static elimination light to eliminate static charge after the transfer of the toner image and before it is charged; and a well-known image forming apparatus such as an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and reducing the relative temperature.

[0258] In the case of an intermediate transfer method apparatus, the transfer means may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer means for primaryly transferring the toner image formed on the surface of an electrophotographic photoreceptor to the surface of the intermediate transfer body; and a secondary transfer means for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

[0259] The image forming apparatus according to this embodiment may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing method using a liquid developer).

[0260] In the image forming apparatus according to this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor according to this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may also include at least one selected from the group consisting of, for example, a charging means, an electrostatic latent image forming means, a developing means, and a transfer means.

[0261] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0262] Figure 2 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. As shown in Figure 2, the image forming apparatus 100 according to this embodiment includes a process cartridge 300 equipped with an electrophotographic photoreceptor 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 body 50. In the image forming apparatus 100, the exposure device 9 is positioned to expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is positioned facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, with a portion of the intermediate transfer body 50 in contact with the electrophotographic photoreceptor 7. Although not shown, the apparatus also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of transfer means.

[0263] In Figure 2, the process cartridge 300 integrally supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging means), a developing device 11 (an example of a developing means), and a cleaning device 13 (an example of a cleaning means) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is positioned to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member, rather than a cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0264] Figure 2 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) for supplying lubricant 14 to the surface of the electrophotographic photoreceptor 7, and a fibrous member 133 (flat brush-shaped) for assisting cleaning. These can be arranged as needed.

[0265] The following describes the various components of the image forming apparatus according to this embodiment.

[0266] -Charging device- As the charging device 8, for example, a contact-type charger using conductive or semiconductive charging rollers, charging brushes, charging films, charging rubber blades, charging tubes, etc. may be used. Non-contact roller chargers, known chargers such as scorotron chargers and corotron chargers that utilize corona discharge may also be used.

[0267] -Exposure equipment- Examples of exposure devices 9 include optical equipment that exposes the surface of an electrophotographic photoreceptor 7 to a predetermined image using light such as semiconductor laser light, LED light, or liquid crystal shutter light. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. As for the wavelength of the semiconductor laser, near-infrared lasers with an oscillation wavelength of around 780 nm are the mainstream. However, the wavelength is not limited to this, and lasers with oscillation wavelengths in the 600 nm range or blue lasers with oscillation wavelengths between 400 nm and 450 nm may also be used. Furthermore, for color image formation, surface-emitting laser light sources capable of outputting multiple beams are also effective.

[0268] -Developing equipment- Examples of developing devices 11 include general developing devices that develop by contacting or not contacting the developing agent. There are no particular restrictions on the developing device 11 as long as it has the above-described functions, and it can be selected according to the purpose. For example, known developing devices that have the function of applying a one-component or two-component developing agent to the electrophotographic photoreceptor 7 using a brush, roller, etc. Among these, those that use a developing roller that holds the developing agent on its surface are preferred.

[0269] The developer used in the developing device 11 may be a one-component developer consisting of toner alone, or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. Well-known developers are applicable.

[0270] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade method, a fur brush cleaning method or a developing-simultaneous cleaning method may also be used.

[0271] -Transfer device- Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., and transfer chargers that are known themselves, such as scorotron transfer chargers and corotron transfer chargers that utilize corona discharge.

[0272] -Intermediate Transcript- As the intermediate transfer body 50, a belt-shaped material (intermediate transfer belt) containing semiconducting polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, etc. is used. In addition to the belt shape, a drum-shaped intermediate transfer body may also be used.

[0273] Figure 3 is a schematic diagram showing another example of the image forming apparatus according to this embodiment. The image forming apparatus 120 shown in Figure 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 body 50, and one electrophotographic photoreceptor is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. [Examples]

[0274] The electrophotographic photoreceptor according to this embodiment will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing procedures, etc., shown in the following examples can be modified as appropriate without departing from the spirit of this embodiment. Therefore, the scope of the electrophotographic photoreceptor according to this embodiment should not be interpreted as being limited by the specific examples shown below. In addition,

[0275] [Example 1] (Grinding of electron-transporting compound particles) 6.4 g of the example compound (1-1) of formula (P1) (manufactured by Clariant), 72 g of zirconia beads with a diameter of 0.3 mm, and 1.0 g of sodium chloride were placed in a zirconia container and ground for 2 hours at a rotation speed of 500 rpm using a planetary mill (manufactured by Fritsch: P-7 Classic Line). After grinding, the pigment particles were separated by filtration while washing the zirconia beads with 500 ml of distilled water. The resulting aqueous dispersion of pigment particles was centrifuged, and the supernatant water was removed by decantation to isolate the pigment. The isolated pigment was repeatedly washed with water until its electrical conductivity was 10 μS / cm or less, and then dried in a freeze-dryer for 48 hours to obtain 4.9 g of ground pigment particles. The aspect ratio of the pigment particles was 7.2 before grinding and 4.8 after grinding.

[0276] (Formation of the lower layer) 32 parts by mass of electron-transporting compound particles obtained, 6 parts by mass of blocked isocyanate (product name: Sumijule 3175, manufactured by Sumitomo Bayern Urethanes Co., Ltd.), 1 part by mass of the compound represented by the following structural formula (AK-1), and 25 parts by mass of methyl ethyl ketone were mixed for 30 minutes. Then, 5 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.), 3 parts by mass of silicone balls (product name: Tospar 120, manufactured by Momentive Performance Materials Co., Ltd.), and 0.01 parts by mass of Toray Dow Corning silicone oil (product name: SH29PA, manufactured by Dow Corning) as a leveling agent were added, and the mixture was dispersed in a sand mill for 1.8 hours (i.e., the dispersion time was 1.8 hours) to obtain a coating solution for forming an undercoat.

[0277] [ka]

[0278] Furthermore, the coating solution for forming the undercoat layer obtained by the immersion coating method was applied to an aluminum substrate (conductive support) with a diameter of 47 mm, a length of 357 mm, and a wall thickness of 1 mm, and dried and cured at 180°C for 30 minutes to obtain an undercoat layer with a thickness of 5 μm.

[0279] (Formation of charge generation layer 1) As a charge-generating material, hydroxygallium phthalocyanine was prepared, having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 16.3°, 25.0°, and 28.3° in its X-ray diffraction spectrum using Cukα characteristic X-rays. A mixture of 15 parts by mass of hydroxygallium phthalocyanine, 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.), and 200 parts by mass of n-butyl acetate was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the resulting dispersion and stirred to obtain a coating solution for forming the charge-generating layer. This coating solution was immersed onto the undercoat and dried at 146°C for 10 minutes to form a charge-generating layer 1 with a thickness of 0.2 μm.

[0280] (Formation of charge transport layer 1) 38 parts by mass of charge transport agent (HT-1), 10 parts by mass of charge transport agent (HT-2), and 52 parts by mass of polycarbonate (A) (viscosity average molecular weight 48,000) were dissolved in 800 parts by mass of tetrahydrofuran. 8 parts by mass of tetrafluoroethylene resin (Lubron L5, manufactured by Daikin Industries, Ltd., average particle size 300 nm) were added, and the mixture was dispersed at 5,500 rpm for 2 hours using a homogenizer (Ultra-Turrax, manufactured by IKA) to obtain a coating solution for forming the charge transport layer. This coating solution was immersed and coated onto the charge generating layer 1, and dried at 148°C for 40 minutes to form a charge transport layer 1 with a thickness of 26 μm. The electrophotographic photoreceptor of Example 1 was obtained by the above treatment.

[0281] [ka]

[0282] [ka]

[0283] [Examples 2 to 14, and Comparative Examples 1 to 5] An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that the presence or absence of pulverization of electron-transporting compound particles, the formation of the undercoat layer, the formation of the charge generation layer 1, and the formation of the charge transport layer 1 were modified as appropriate as shown in Table 1.

[0284] (Formation of charge generation layer 2) As a charge-generating material, hydroxygallium phthalocyanine was prepared, having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 16.3°, 25.0°, and 28.3° in its X-ray diffraction spectrum using Cukα characteristic X-rays. A mixture of 15 parts by mass of hydroxygallium phthalocyanine, 10 parts by mass of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.), and 200 parts by mass of n-butyl acetate was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the resulting dispersion and stirred to obtain a coating solution for forming the charge-generating layer. This coating solution was immersed onto the undercoat and dried at 80°C for 15 minutes to form a charge-generating layer 2 with a thickness of 0.2 μm.

[0285] (Formation of charge transport layer 2) 38 parts by mass of charge transport agent (HT-1), 10 parts by mass of charge transport agent (HT-2), and 52 parts by mass of polycarbonate (A) (viscosity average molecular weight 48,000) were dissolved in 800 parts by mass of tetrahydrofuran. 8 parts by mass of tetrafluoroethylene resin (Lubron L5, manufactured by Daikin Industries, Ltd., average particle size 300 nm) were added, and the mixture was dispersed at 5,500 rpm for 2 hours using a homogenizer (Ultra-Turrax, manufactured by IKA) to obtain a coating solution for forming a charge transport layer. This coating solution was immersed and applied onto the charge generation layer 1, and dried at 140°C for 40 minutes to form a charge transport layer 2 with a thickness of 40 μm.

[0286] <Rating> -Sensitivity (electron transportability) evaluation- The following evaluations were conducted under three conditions: high temperature and high humidity (28°C, 85%RH), indoor environment (20°C, 50%RH), and low temperature and low humidity (10°C, 10%RH). Sensitivity was evaluated as the half-exposure amount when the electrophotographic photoreceptor was charged to +800V. Specifically, first, using an electrostatic copying paper test apparatus (electrostatic analyzer EPA-8300, manufactured by Kawaguchi Electric Co., Ltd.), each example of the electrophotographic photoreceptor was charged to +800V in an environment of 20°C / 40% relative humidity. Then, the light from a tungsten lamp was converted to monochromatic light of 780 nm using a monochromator, and 1 μW / cm² was applied to the surface of the electrophotographic photoreceptor. 2 The light intensity was adjusted and the light was irradiated accordingly. Then, the half-exposure dose (μJ / cm²) at which the surface potential Vo(V) of the electrophotographic photoreceptor immediately after charging is halved by light irradiation was determined. 2 The half-exposure values ​​obtained were measured. The half-exposure values ​​were classified according to the following criteria. A: Half-life exposure is 0.08 μJ / cm² 2 The results were as follows: B: Half-life exposure is 0.08 μJ / cm² 2 Over 0.10 μJ / cm² 2 The results were as follows: C: Half-life exposure is 0.10 μJ / cm² 2 Over 0.12 μJ / cm² 2 The results were as follows: D: Half-life exposure is 0.12 μJ / cm² 2 It exceeded expectations.

[0287] - Leak resistance (static charge resistance) evaluation - The following evaluations were conducted under three conditions: high temperature and high humidity (30°C, 85%RH), indoor environment (20°C, 50%RH), and low temperature and low humidity (10°C, 10%RH). We evaluated the suppression of deterioration in chargeability due to leakage current by utilizing the phenomenon in which an electric current flows and point-like image defects occur when carbon fibers penetrate the photosensitive layer and undercoat layer and reach the conductive substrate. The above photoreceptor was incorporated into a DocuCentre-V C7775 manufactured by Fujifilm Business Innovation Co., Ltd., and carbon fiber (average diameter 7 μm, average length 120 μm) was mixed into the developer at a ratio of 0.15 mass% relative to the amount of developer. 40,000 black images with an image density of 20% were continuously printed on A4 paper. The presence or absence of point-like image defects in the 30,000th image was visually observed, and the degree of image defects was classified into A to D below. A: Fewer than 5 point-like image defects. B: There are 5 to 10 point-like image defects. C: There are 10 to 20 point-like image defects. D: More than 20 point-like image defects.

[0288] [Table 1]

[0289] Note that the numbers for the types of crystalline electron-transporting compound particles in Table 1 are the same as the numbers for the example compounds in formulas (P1) to (P8) described above.

[0290] As shown in Table 1, the electrophotographic photoreceptor of the example was found to have superior chargeability and electron transport properties compared to the electrophotographic photoreceptor of the comparative example. [Explanation of Symbols]

[0291] 1: Undercoat layer, 2: Charge generation layer, 3: Charge transport layer, 4: Conductive support, 5: Photosensitive layer, 7A: Electrophotographic photoreceptor, 7: Electrophotographic photoreceptor, 8: Charging device, 9: Exposure device, 11: Developing device, 13: Cleaning device, 14: Lubricant, 40: Transfer device, 50: Intermediate transfer body, 100: Image forming device, 120: Image forming device, 131: Cleaning blade, 132: Fibrous member (roll type), 133: Fibrous member (flat brush type), 300: Process cartridge

Claims

1. A conductive support has an undercoat layer and a photosensitive layer. The aforementioned underlayer contains crystalline electron-transporting compound particles, The average aspect ratio of the electron-transporting compound particles is 2.3 or more and 4.8 or less. The full width at half maximum of the maximum intensity peak in the X-ray diffraction measurement of the aforementioned underlayer, measured from the thickness direction, is 5° or less. The relative integrated intensity of each peak in the X-ray diffraction measurement of the aforementioned underlayer, measured from the thickness direction, is I １ The lower layer is then prepared as a powder with a volume-average particle size of 5 μm or less, and the relative integrated intensity of each peak in the X-ray diffraction measurement is defined as I ２ In this case, the value of the maximum value Nmax among the orientation index N expressed by the following formula (1) is between 1 and 3. Electrophotographic photoreceptor. [Math 1]

2. The electrophotographic photoreceptor according to claim 1, wherein the full width at half maximum is 1.0° or less.

3. The electrophotographic photoreceptor according to claim 2, wherein the full width at half maximum is 0.7° or less.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the value of the maximum value Nmax is 1 or more and 2.7 or less.

5. The electrophotographic photoreceptor according to claim 4, wherein the value of the maximum value Nmax is 1 or more and 2.5 or less.

6. The electrophotographic photoreceptor according to any one of Claims 1 to 5, wherein the average aspect ratio of the electron-transporting compound particles is 2.3 or more and 4.5 or less.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the electron-transporting compound particles are particles of a compound represented by any one of the following formulas (P1) to (P8). 【Chemistry 1】 In formula (P1), R １１ and R １２ and R １３ and R １４ and R １５ and R １６ and R １７ and R １８ 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; R １１ and R １２ and R １２ and R １３ and R １３ and R １４ each independently may be linked to each other to form a ring; R １５ and R １６ and R １６ and R １７ and R １７ and R １８ each independently may be linked to each other to form a ring. In formula (P2), R ２１ and R ２２ and R ２３ and R ２４ and R ２５ and R ２６ and R ２７ and R ２８ 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; R ２１ and R ２２ and R ２２ and R ２３ and R ２３ and R ２４ each independently may be linked to each other to form a ring; R ２５ and R ２６ and R ２６ and R ２７ and R ２７ and R ２８ each independently may be linked to each other to form a ring. In formula (P3), R ３１ , R ３２ , R ３３ , R ３４ , R ３５ and R ３６ Each of these 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 formula (P4), 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 formula (P5), R ５１ , R ５２ , R ５３ , R ５４ , R ５５ , R ５６ , R ５７ and R ５８ Each of these 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 formula (P6), 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 formula (P7), R ７１ , R ７２ , R ７３ , R ７４ , R ７５ , R ７６ , R ７７ , and 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 ). In formula (P8), R ８１ , R ８２ , R ８３ , R ８４ , R ８５ , R ８６ and R ８７ 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 ).

8. The electrophotographic photoreceptor according to claim 7, wherein the electron-transporting compound particles are particles of a compound represented by any one of the formulas (P1) to (P4).

9. The electrophotographic photoreceptor according to claim 8, wherein the electron-transporting compound particles are particles of the compound represented by formula (P4).

10. The electrophotographic photoreceptor according to any one of claims 1 to 9, wherein the content of the electron-transporting compound particles is 50% by mass or more and 80% by mass or less with respect to the total mass of the undercoat layer.

11. The electrophotographic photoreceptor is provided according to any one of claims 1 to 10, A process cartridge that is attached to and detached from an image forming apparatus.

12. An electrophotographic photoreceptor according to any one of claims 1 to 10, A charging means for charging the surface of the electrophotographic photoreceptor, An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, A developing means that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, A transfer means for transferring the toner image onto the surface of a recording medium, An image forming apparatus equipped with the following features.

Images