Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that reduces the difference in electric characteristics between the early stage and the final stage of repeated image formation and reduces the occurrence of burn-in ghost on an image, wherein these operations are achieved over a relatively large setting area related to the intensities of charging and exposure.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate, an undercoat layer, and a photosensitive layer. The undercoat layer contains a binder resin and a perinone compound. The photosensitive layer contains polyester resin (1) having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2), a dicarboxylic acid unit (A3), and a dicarboxylic acid unit (A4), and a diol unit (B). The mass ratio of the polyester resin (1) in the photosensitive layer is 15 mass% or more.SELECTED DRAWING: None

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 discloses an electrophotographic photoreceptor that includes a conductive substrate, an undercoat layer, and a photosensitive layer, in which the undercoat layer contains a perinone compound and polyurethane.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer, and a photosensitive layer, in which the undercoat layer contains a perinone compound and an acceptor compound.

[0004] Patent Document 3 discloses an electrophotographic photoreceptor including a conductive substrate, an undercoat layer, and a photosensitive layer, in which the undercoat layer contains a perinone compound, an amine compound having an ionization potential of 5.4 eV or more and 5.9 eV or less, and a binder resin.

[0005] Patent Document 4 discloses an electrophotographic photoreceptor having, on a conductive support, an intermediate layer containing N-type semiconductive particles and a photosensitive layer containing P-type pigments and N-type pigments.

[0006] Patent Document 5 discloses an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer provided on a conductive support, in which the intermediate layer contains a polyolefin resin and an organic electron transport material, and the organic electron transport material is a compound selected from the group consisting of imide-based compounds, benzimidazole-based compounds, quinone-based compounds, cyclopentadienylidene-based compounds, azo-based compounds, and derivatives thereof.

[0007] Patent Document 6 discloses an electrophotographic photoreceptor in which an undercoat layer and a photosensitive layer are laminated on a conductive support, and at least one of the undercoat layer and the photosensitive layer contains a compound represented by formula A (a compound having a benzimidazole ring introduced on one side of a naphthalenetetracarboxylic diimide skeleton). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2020-046640 A [Patent Document 2] JP 2020-046641 A [Patent Document 3] JP 2020-101652 A [Patent Document 4] JP 2004-354697 A [Patent Document 5] JP 2011-095665 A [Patent Document 6] Patent Publication No. 2021-015223 Summary of the Invention [Problem to be solved by the invention]

[0009] The present disclosure aims to provide an electrophotographic photoreceptor in which, compared with a case in which the mass ratio of polyester resin (1) in the photosensitive layer is less than 15 mass %, the difference in electrical properties between the initial and final stages of repeated image formation is small, and image burn-in ghosts are less likely to occur, and these characteristics are realized over a relatively wide setting range of charging and exposure intensity. [Means for solving the problem]

[0010] Specific means for solving the above problems include the following aspects: Each formula is the same as the formula with the same number described below.

[0011] <1> A conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer, the undercoat layer contains a binder resin and at least one perinone compound selected from the group consisting of compounds represented by formula (1) and compounds represented by formula (2), the photosensitive layer contains a polyester resin (1) having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4), and a diol unit (B) represented by formula (B), The mass ratio of the polyester resin (1) in the photosensitive layer is 15 mass% or more. Electrophotographic photoreceptor. <2> the mass ratio of the perinone compound in the undercoat layer is 30% by mass or more and 90% by mass or less; <1> The electrophotographic photoreceptor according to claim 1. <3> The undercoat layer contains polyurethane. <1> or <2> The electrophotographic photoreceptor according to claim 1. <4> The average thickness of the undercoat layer is 5 μm or more and 30 μm or less. <1> ~ <3> 13. The electrophotographic photoreceptor according to claim 12, <5> The photosensitive layer further contains a polycarbonate resin. <1> ~ <4> 13. The electrophotographic photoreceptor according to claim 12, <6> The polyester resin (1) has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8). <1> ~ <5> 13. The electrophotographic photoreceptor according to claim 12, <7> The photosensitive layer contains gallium phthalocyanine as a charge generating material. <1> ~ <6> 13. The electrophotographic photoreceptor according to claim 12, <8> <1> ~ <7> The electrophotographic photoreceptor according to any one of the above items is provided, A process cartridge that is detachably attached to an image forming apparatus. <9> <1> ~ <7> and an electrophotographic photoreceptor according to any one of the above items. a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: Effect of the Invention

[0012] <1> , <3> , <5> , <6> or <7> According to the invention, there is provided an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur, compared to when the mass ratio of the polyester resin (1) in the photosensitive layer is less than 15 mass %, and these characteristics are realized over a relatively wide setting range of charging and exposure intensity. <2> According to the invention, there is provided an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur, compared with cases in which the mass proportion of the perinone compound in the undercoat layer is less than 30 mass % or more than 90 mass %, and these are realized over a relatively wide setting range of charging and exposure intensity. <4> According to the invention, there is provided an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small, and image burn-in ghosts are less likely to occur, compared to when the average thickness of the undercoat layer is less than 5 μm or more than 30 μm, and these characteristics are realized over a relatively wide setting range of charging and exposure intensity. <8> According to the invention, there is provided a process cartridge equipped with an electrophotographic photosensitive member in which the difference in electrical characteristics between the beginning and end of repeated image formation is small and ghost images are less likely to occur compared to when the mass ratio of the polyester resin (1) in the photosensitive layer is less than 15 mass %, and these characteristics are realized over a relatively wide setting range of charging and exposure intensity. <9> According to the invention, there is provided an image forming apparatus equipped with an electrophotographic photoreceptor in which the difference in electrical properties between the beginning and end of repeated image formation is small and image burn-in ghosts are less likely to occur, compared to when the mass ratio of the polyester resin (1) in the photosensitive layer is less than 15 mass %, and these are realized over a relatively wide setting range of charging and exposure intensity. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photoreceptor according to the present embodiment. [Diagram 2] FIG. 4 is a partial cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor according to the present embodiment. [Diagram 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. 4 is a schematic configuration diagram illustrating another example of an image forming apparatus according to the present embodiment. [Diagram 5] FIG. 13 is a diagram showing the evaluation criteria for burn-in ghosts in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiments, and are not intended to limit the scope of the embodiments.

[0015] In the present disclosure, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0016] In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0017] When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0018] In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0019] In the present disclosure, unless otherwise specified, the alkyl group and the alkylene group include any of straight-chain, branched, and cyclic groups.

[0020] In the present disclosure, a hydrogen atom in an organic group, an aromatic ring, a linking group, an alkyl group, an alkylene group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, and the like may be substituted with a halogen atom.

[0021] In the present disclosure, when a compound is shown by a structural formula, the symbols (C and H) representing carbon atoms and hydrogen atoms in the hydrocarbon group and / or hydrocarbon chain may be omitted.

[0022] In the present disclosure, the term "structural unit" of a copolymer or resin is synonymous with a monomer unit.

[0023] <Electrophotographic photoreceptor> The electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") according to this embodiment includes a conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer.

[0024] Fig. 1 is a partial cross-sectional view showing an example of the layer structure of a photoreceptor according to the present embodiment. The photoreceptor 10A shown in Fig. 1 has a laminated photosensitive layer. The photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called function-separated photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3.

[0025] Fig. 2 is a partial cross-sectional view showing another example of the layer structure of the photoreceptor according to the present embodiment. The photoreceptor 10B shown in Fig. 2 has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are laminated in this order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5.

[0026] The photoreceptor according to this embodiment is The undercoat layer contains a binder resin and at least one perinone compound selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), the photosensitive layer contains a polyester resin (1) having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4), and a diol unit (B) represented by the following formula (B), The mass ratio of the polyester resin (1) in the photosensitive layer is 15 mass % or more.

[0027] [ka]

[0028] In formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 11 and R 12 , R 12 and R 13 and R 13 and R 14 may each independently be linked to each other to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 may each independently be linked to each other to form a ring. In formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 21 and R 22 , R 22 and R 23 and R 23 and R 24 may each independently be linked to each other to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 may each independently be linked to each other to form a ring.

[0029] [ka]

[0030] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra 202 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent; L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )-, and n B1 is 0, 1 or 2. Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0031] In the present disclosure, a compound represented by formula (1) is referred to as a perinone compound (1), and a compound represented by formula (2) is referred to as a perinone compound (2).

[0032] When the photosensitive layer of the photoreceptor according to the present embodiment is a laminated type photosensitive layer consisting of a charge generating layer and a charge transporting layer as in the photoreceptor 10A shown in Fig. 1, at least the charge transporting layer contains the polyester resin (1). The charge generating layer may or may not contain the polyester resin (1).

[0033] The photoconductor according to this embodiment has little difference in electrical characteristics between the beginning and end of repeated image formation, and is less susceptible to image burn-in ghosts, and these characteristics are realized over a relatively wide range of settings related to charging and exposure intensity. "Burning ghost" refers to an image defect in which the surface potential of the photosensitive layer decreases in areas with a long exposure history, causing the density of a halftone image to become high. The mechanism by which the photoreceptor according to this embodiment exhibits the above-mentioned effects is presumed to be as follows.

[0034] It is known that the use of the perinone compound (1) and / or the perinone compound (2) in the undercoat layer can provide good initial electrical properties. Here, when a resin other than polyester resin (1) is used in the photosensitive layer (charge transport layer in the case of a laminated photosensitive layer), there is a large difference between the electron injection from the photosensitive layer (charge generation layer in the case of a laminated photosensitive layer) to the undercoat layer during exposure and the hole injection from the charge generation material in the photosensitive layer to the charge transport material (from the charge generation layer to the charge transport layer in the case of a laminated photosensitive layer), and it is considered that charges gradually accumulate with repeated exposure and charging. As a result, the difference in electrical properties between the initial and final stages of repeated image formation becomes large. Moreover, this charge accumulation is thought to be more noticeable in areas with a long history of exposure, resulting in ghost images being burned in. Furthermore, if the charging and exposure conditions are changed, the difference between the above-mentioned "electron injection property" and "hole injection property" is also thought to vary significantly. As a result, the difference in electrical characteristics between the initial and final stages of repeated image formation and the appearance of burn-in ghosts also change. In contrast, when polyester resin (1) is used in the photosensitive layer (charge transport layer in the case of a laminated photosensitive layer), the difference between the above-mentioned "electron injection property" and "hole injection property" is considered to be small. As a result, the difference in electrical characteristics between the initial and final stages of repeated image formation is small, and ghost images are less likely to occur. Furthermore, these are realized over a relatively wide range of settings related to charging and exposure conditions.

[0035] In the photoreceptor according to the present embodiment, the mass ratio of the polyester resin (1) in the photosensitive layer is 15% by mass or more. If the mass ratio of the polyester resin (1) in the photosensitive layer is less than 15% by mass, the film strength and crack resistance of the photosensitive layer become insufficient, and the maintenance of electrical properties decreases. From the viewpoint of suppressing this phenomenon, the mass ratio of the polyester resin (1) in the photosensitive layer is 15% by mass or more, preferably 20% by mass or more, and more preferably 25% by mass or more. From the viewpoint of initial electrical characteristics, the mass proportion of the polyester resin (1) in the photosensitive layer is preferably 80 mass % or less, more preferably 75 mass % or less, and even more preferably 70 mass % or less.

[0036] In the photoreceptor according to this embodiment, the mass proportion of the perinone compound in the undercoat layer (the total mass proportion of the perinone compound (1) and the perinone compound (2)) is preferably 30 mass % or more, more preferably 40 mass % or more, and even more preferably 50 mass % or more, from the viewpoint of imparting electrical properties suitable for electrophotography to the undercoat layer. The mass proportion of the perinone compound in the undercoat layer (the total mass proportion of perinone compound (1) and perinone compound (2)) is preferably 90 mass% or less, more preferably 80 mass% or less, and even more preferably 70 mass% or less, from the viewpoint of flexibility and elasticity of the undercoat layer.

[0037] The perinone compound, the polyester resin (1) and each layer of the photoreceptor will be described in detail below.

[0038] [Perinone compound (1), Perinone compound (2)] The perinone compound (1) is a compound represented by the following formula (1): The perinone compound (2) is a compound represented by the following formula (2):

[0039] [ka]

[0040] In formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom.11 and R 12 , R 12 and R 13 and R 13 and R 14 may each independently be linked to each other to form a ring. 15 and R 16 , R 16 and R 17 and R 17 and R 18 may each independently be linked to each other to form a ring.

[0041] In formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. 21 and R 22 , R 22 and R 23 and R 23 and R 24 may each independently be linked to each other to form a ring. 25 and R 26 , R 26 and R 27 and R 27 and R 28 may each independently be linked to each other to form a ring.

[0042] In formula (1), R 11 ~R 18 The alkyl group represented by the formula (I) may be a substituted or unsubstituted alkyl group.

[0043] In formula (1), R 11 ~R 18Examples of the unsubstituted alkyl group represented by the formula (I) include a linear alkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and a cyclic alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0044] Examples of the linear alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0045] Examples of the branched alkyl group having 3 to 20 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0046] Examples of the cyclic alkyl group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0047] Among the above, as the unsubstituted alkyl group, a straight-chain alkyl group such as a methyl group or an ethyl group is preferable.

[0048] Substituents in the alkyl group include an alkoxy group, a hydroxy group, a carboxy group, a nitro group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkoxy group that replaces the hydrogen atom in the alkyl group is R 11 ~R 18 Examples of the alkoxy group include the same as the unsubstituted alkoxy group represented by the following formula:

[0049] In formula (1), R 11 ~R 18 The alkoxy group represented by the following formula (I) includes a substituted or unsubstituted alkoxy group.

[0050] In formula (1), R 11 ~R 18 Examples of the unsubstituted alkoxy group represented by the formula (I) include linear, branched or cyclic alkoxy groups having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 4).

[0051] Specific examples of linear alkoxy groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, and an n-decyloxy group. Specific examples of branched alkoxy groups include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, an isoheptyloxy group, a sec-heptyloxy group, a tert-heptyloxy group, an isooctyloxy group, a sec-octyloxy group, a tert-octyloxy group, an isononyloxy group, a sec-nonyloxy group, a tert-nonyloxy group, an isodecyloxy group, a sec-decyloxy group, and a tert-decyloxy group. Specific examples of the cyclic alkoxy group include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group, a cyclononyloxy group, and a cyclodecyloxy group. Among these, the unsubstituted alkoxy group is preferably a linear alkoxy group.

[0052] Substituents in the alkoxy group include an aryl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a hydroxyl group, a carboxy group, a nitro group and a halogen atom (such as a fluorine atom, a bromine atom or an iodine atom). The aryl group that replaces the hydrogen atom in the alkoxy group is, for example, 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula: The alkoxycarbonyl group that replaces the hydrogen atom in the alkoxy group is, for example, 11 ~R 18 Examples of the alkoxycarbonyl group include the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that replaces the hydrogen atom in the alkoxy group is, for example, 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0053] In formula (1), R 11 ~R 18 The aralkyl group represented by the following formula (I) includes a substituted or unsubstituted aralkyl group.

[0054] In formula (1), R 11 ~R 18 The unsubstituted aralkyl group represented by the following formula is preferably an aralkyl group having 7 to 30 carbon atoms, more preferably an aralkyl group having 7 to 16 carbon atoms, and even more preferably an aralkyl group having 7 to 12 carbon atoms.

[0055] Examples of the unsubstituted aralkyl group having 7 to 30 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthracylmethyl group, and a phenyl-cyclopentylmethyl group.

[0056] Substituents in the aralkyl group include an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, an iodine atom, etc.). The alkoxy group that substitutes the hydrogen atom in the aralkyl group is, for example, R 11 ~R 18 Examples of the alkoxy group include the same as the unsubstituted alkoxy group represented by the following formula: The alkoxycarbonyl group that replaces a hydrogen atom in the aralkyl group is, for example, 11 ~R 18 Examples of the alkoxycarbonyl group include the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that replaces the hydrogen atom in the aralkyl group is, for example, 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0057] In formula (1), R 11 ~R 18 The aryl group represented by the formula (I) may be a substituted or unsubstituted aryl group.

[0058] In formula (1), R 11 ~R 18 The unsubstituted aryl group represented by the following formula is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms.

[0059] Examples of the aryl group having 6 to 30 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, a 2-naphthyl group, a 9-anthryl group, a 9-phenanthryl group, a 1-pyrenyl group, a 5-naphthacenyl group, a 1-indenyl group, a 2-azulenyl group, a 9-fluorenyl group, a biphenylenyl group, an indacenyl group, a fluoranthenyl group, an acenaphthylenyl group, an aceanthryllenyl group, a phenalenyl group, and a fluorenyl group. Examples of the anthryl group include anthryl, bianthracenyl, teranthracenyl, quaternary anthracenyl, anthraquinolyl, phenanthryl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, pleiadenyl, picenyl, perylenyl, pentaphenyl, pentacenyl, tetraphenylenyl, hexaphenyl, hexacenyl, rubicenyl, and coronenyl groups. Of the above, the phenyl group is preferred.

[0060] Substituents in the aryl group include an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom). The alkyl group that substitutes the hydrogen atom in the aryl group is, for example, 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula: The alkoxy group that substitutes the hydrogen atom in the aryl group is, for example, 11 ~R 18 Examples of the alkoxy group include the same as the unsubstituted alkoxy group represented by the following formula: The alkoxycarbonyl group that replaces the hydrogen atom in the aryl group is, for example, 11 ~R 18 Examples of the alkoxycarbonyl group include the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that replaces the hydrogen atom in the aryl group is, for example, 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0061] In formula (1), R 11 ~R18 The aryloxy group represented by the following formula (-O-Ar, Ar represents an aryl group) includes a substituted or unsubstituted aryloxy group.

[0062] In formula (1), R 11 ~R 18 The unsubstituted aryloxy group represented by the following formula 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.

[0063] Examples of the aryloxy group having 6 to 30 carbon atoms include a phenyloxy group (phenoxy group), a biphenyloxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 9-anthryloxy group, a 9-phenanthryloxy group, a 1-pyrenyloxy group, a 5-naphthacenyloxy group, a 1-indenyloxy group, a 2-azulenyloxy group, a 9-fluorenyloxy group, a biphenylenyloxy group, an indacenyloxy group, a fluoranthenyloxy group, an acenaphthylenyloxy group, an aceanthryloxy group, a phenalenyloxy group, and a fluorenyloxy group. Examples of the aryloxy group include phenyloxy, anthryloxy, bianthracenyloxy, teranthracenyloxy, quaternary anthracenyloxy, anthraquinolyloxy, phenanthryloxy, triphenylenyloxy, pyrenyloxy, chrysenyloxy, naphthacenyloxy, pleiadenyloxy, picenyloxy, perylenyloxy, pentaphenyloxy, pentacenyloxy, tetraphenylenyloxy, hexaphenyloxy, hexacenyloxy, rubicenyloxy, and coronenyloxy. Among the above, the phenyloxy group (phenoxy group) is preferred.

[0064] Substituents in the aryloxy group include an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a halogen atom (such as a fluorine atom, a bromine atom, an iodine atom, etc.). The alkyl group that substitutes the hydrogen atom in the aryloxy group is, for example, 11 ~R 18Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula: The alkoxycarbonyl group that replaces the hydrogen atom in the aryloxy group is, for example, 11 ~R 18 Examples of the alkoxycarbonyl group include the unsubstituted alkoxycarbonyl group represented by the following formula: The aryloxycarbonyl group that replaces the hydrogen atom in the aryloxy group is, for example, 11 ~R 18 Examples of the aryloxycarbonyl group include the unsubstituted aryloxycarbonyl group represented by the following formula:

[0065] In formula (1), R 11 ~R 18 The alkoxycarbonyl group represented by the following formula (-CO-OR, where R represents an alkyl group) includes a substituted or unsubstituted alkoxycarbonyl group.

[0066] In formula (1), R 11 ~R 18 The number of carbon atoms in the alkyl chain in the unsubstituted alkoxycarbonyl group represented by the following formula is preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less, and even more preferably 1 or more and 10 or less.

[0067] Examples of the alkoxycarbonyl group having an alkyl chain carbon number of 1 to 20 include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, an n-butoxycarbonyl group, a sec-butoxybutylcarbonyl group, a tert-butoxycarbonyl group, a pentaoxycarbonyl group, a hexaoxycarbonyl group, a heptoxycarbonyl group, an octaoxycarbonyl group, a nonaoxycarbonyl group, a decaoxycarbonyl group, a dodecaoxycarbonyl group, a tridecaoxycarbonyl group, a tetradecaoxycarbonyl group, a pentadecaoxycarbonyl group, a hexadecaoxycarbonyl group, a heptadecaoxycarbonyl group, an octadecaoxycarbonyl group, a nonadecaoxycarbonyl group, and an icosaoxycarbonyl group.

[0068] Substituents in the alkoxycarbonyl group include an aryl group, a hydroxy group and a halogen atom (such as a fluorine atom, a bromine atom, an iodine atom, etc.). The aryl group replacing the hydrogen atom in the alkoxycarbonyl group is, for example, 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula:

[0069] In formula (1), R 11 ~R 18 The aryloxycarbonyl group represented by the following formula (-CO-OAr, Ar represents an aryl group) includes a substituted or unsubstituted aryloxycarbonyl group.

[0070] In formula (1), R 11 ~R 18 The number of carbon atoms in the aryl group in the unsubstituted aryloxycarbonyl group represented by the following formula is preferably 6 or more and 30 or less, more preferably 6 or more and 14 or less, and further preferably 6 or more and 10 or less.

[0071] Examples of the aryloxycarbonyl group having an aryl group having 6 to 30 carbon atoms include a phenoxycarbonyl group, a biphenyloxycarbonyl group, a 1-naphthyloxycarbonyl group, a 2-naphthyloxycarbonyl group, a 9-anthryloxycarbonyl group, a 9-phenanthryloxycarbonyl group, a 1-pyrenyloxycarbonyl group, a 5-naphthacenyloxycarbonyl group, a 1-indenyloxycarbonyl group, a 2-azulenyloxycarbonyl group, a 9-fluorenyloxycarbonyl group, a biphenylenyloxycarbonyl group, an indacenyloxycarbonyl group, a fluoranthenyloxycarbonyl group, an acenaphthylenyloxycarbonyl group, an aceanthryloxycarbonyl group, a phenalenyloxycarbonyl group, and a fluorenyloxycarbonyl group. Examples of the alkyl group include anthryloxycarbonyl group, bianthracenyloxycarbonyl group, teranthracenyloxycarbonyl group, quaternanthracenyloxycarbonyl group, anthraquinolyloxycarbonyl group, phenanthryloxycarbonyl group, triphenylenyloxycarbonyl group, pyrenyloxycarbonyl group, chrysenyloxycarbonyl group, naphthacenyloxycarbonyl group, pleiadenyloxycarbonyl group, picenyloxycarbonyl group, perylenyloxycarbonyl group, pentaphenyloxycarbonyl group, pentacenyloxycarbonyl group, tetraphenylenyloxycarbonyl group, hexaphenyloxycarbonyl group, hexacenyloxycarbonyl group, rubicenyloxycarbonyl group, and coronenyloxycarbonyl group. Among the above, the phenoxycarbonyl group is preferred.

[0072] Substituents 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.). The alkyl group that substitutes the hydrogen atom of the aryloxycarbonyl group is, in formula (1), R 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula:

[0073] In formula (1), R 11 ~R 18An alkoxycarbonylalkyl group represented by (-(C n H 2n )-CO-OR, R represents an alkyl group, and n represents an integer of 1 or more. ) includes a substituted or unsubstituted alkoxycarbonylalkyl group.

[0074] In formula (1), R 11 ~R 18 The alkoxycarbonyl group (-CO-OR) in the unsubstituted alkoxycarbonylalkyl group represented by the formula (1) is 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the alkoxycarbonyl group represented by the following formula:

[0075] In formula (1), R 11 ~R 18 The alkylene chain (-C n H 2n -) includes a linear alkylene chain having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkylene chain having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and a cyclic alkylene chain having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0076] Examples of the linear alkylene chain having 1 to 20 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-undecylene group, an n-dodecylene group, a tridecylene group, an n-tetradecylene group, an n-pentadecylene group, an n-heptadecylene group, an n-octadecylene group, an n-nonadecylene group, and an n-icosylene group.

[0077] Examples of the branched alkylene chain having 3 to 20 carbon atoms include an isopropylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, an isopentylene group, a neopentylene group, a tert-pentylene group, an isohexylene group, a sec-hexylene group, a tert-hexylene group, an isoheptylene group, a sec-heptylene group, a tert-heptylene group, an isooctylene group, a sec-octylene group, a tert-octylene group, an isonylene group, a sec-nonylene group, a tert-nonylene group, an isodecylene group, a sec-decylene group, a tert-decylene group, an isododecylene group, a sec-dodecylene group, a tert-dodecylene group, a tert-tetradecylene group, and a tert-pentadecylene group.

[0078] Examples of the cyclic alkylene chain having 3 to 20 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, and a cyclodecylene group.

[0079] Substituents in the alkoxycarbonylalkyl group include an aryl group, a hydroxy group and a halogen atom (such as a fluorine atom, a bromine atom, an iodine atom, etc.). The aryl group that substitutes the hydrogen atom of the alkoxycarbonylalkyl group is, in formula (1), R 11 ~R 18 Examples of the unsubstituted aryl group include the same groups as the unsubstituted aryl group represented by the following formula:

[0080] In formula (1), R 11 ~R 18 An aryloxycarbonylalkyl group represented by (-(C n H 2n ) -CO-OAr, Ar represents an aryl group, and n represents an integer of 1 or more. ) includes a substituted or unsubstituted aryloxycarbonylalkyl group.

[0081] In formula (1), R 11 ~R 18The aryloxycarbonyl group (-CO-OAr, Ar represents an aryl group) in the unsubstituted aryloxycarbonylalkyl group represented by the formula (1) is, for example, 11 ~R 18 Examples of the aryloxycarbonyl group include the same groups as the aryloxycarbonyl group represented by the following formula:

[0082] In formula (1), R 11 ~R 18 The alkylene chain (-C n H 2n -) in formula (1), R 11 ~R 18 Examples of the alkoxycarbonylalkyl group include the alkylene chain of the alkoxycarbonylalkyl group represented by the following formula:

[0083] Substituents in the aryloxycarbonylalkyl group include an alkyl group, a hydroxy group and a halogen atom (such as a fluorine atom, a bromine atom or an iodine atom). The alkyl group that substitutes the hydrogen atom of the aryloxycarbonylalkyl group is, in formula (1), R 11 ~R 18 Examples of the unsubstituted alkyl group include the same groups as the unsubstituted alkyl group represented by the following formula:

[0084] In formula (1), R 11 ~R 18 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0085] In formula (1), R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 or R 17 and R 18However, examples of the ring structure formed by linking together include a benzene ring, a condensed ring having 10 to 18 carbon atoms (a naphthalene ring, anthracene ring, phenanthrene ring, chrysene ring (benzo[α]phenanthrene ring), tetracene ring, tetraphene ring (benzo[α]anthracene ring), triphenylene ring, etc.). Among the above, the ring structure formed is preferably a benzene ring.

[0086] In formula (2), R 21 ~R 28 As the alkyl group represented by the formula (1), R 11 ~R 18 Examples of the alkyl group include the same groups as those represented by the following formula: In formula (2), R 21 ~R 28 As the alkoxy group represented by the formula (1), R 11 ~R 18 Examples of the alkoxy group include the same groups as the alkoxy group represented by the following formula: In formula (2), R 21 ~R 28 As the aralkyl group represented by the formula (1), R 11 ~R 18 Examples of the aralkyl group include the same groups as those represented by the following formula: In formula (2), R 21 ~R 28 As the aryl group represented by the formula (1), R 11 ~R 18 The aryl group may be the same as the aryl group represented by the following formula: In formula (2), R 21 ~R 28 As the aryloxy group represented by the formula (1), R 11 ~R 18 Examples of the aryloxy group include the same groups as the aryloxy group represented by the following formula: In formula (2), R 21 ~R 28 As the alkoxycarbonyl group represented by the formula (1), R 11 ~R 18 Examples of the alkoxycarbonyl group include the same groups as the alkoxycarbonyl group represented by the following formula: In formula (2), R 21 ~R 28As the aryloxycarbonyl group represented by the formula (1), R 11 ~R 18 Examples of the aryloxycarbonyl group include the same groups as the aryloxycarbonyl group represented by the following formula: In formula (2), R 21 ~R 28 As the alkoxycarbonylalkyl group represented by the formula (1), R 11 ~R 18 Examples of the alkoxycarbonylalkyl group include the same groups as those represented by the following formula: In formula (2), R 21 ~R 28 As the aryloxycarbonylalkyl group represented by the formula (1), R 11 ~R 18 The aryloxycarbonylalkyl group may be the same as that represented by the following formula: In formula (2), R 21 ~R 28 As the halogen atom represented by the formula (1), R 11 ~R 18 Examples of the halogen atom include those represented by the following formula:

[0087] In formula (2), R 21 and R 22 , R 22 and R 23 , R 23 and R 24 , R 25 and R 26 , R 26 and R 27 or R 27 and R 28 However, examples of the ring structure formed by linking together include a benzene ring, a condensed ring having 10 to 18 carbon atoms (a naphthalene ring, anthracene ring, phenanthrene ring, chrysene ring (benzo[α]phenanthrene ring), tetracene ring, tetraphene ring (benzo[α]anthracene ring), triphenylene ring, etc.). Among the above, the ring structure formed is preferably a benzene ring.

[0088] In formula (1), R 11 , R 12 , R 13 , R 14 , R15 , R 16 , R 17 and R 18 are preferably each independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group. In formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 More preferably, each independently is a hydrogen atom or an alkyl group, wherein the preferred form of the alkyl group is as described above. In formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 is particularly preferably a hydrogen atom.

[0089] In formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 are preferably each independently a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, or an aryloxycarbonylalkyl group. In formula (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 More preferably, each independently is a hydrogen atom or an alkyl group, wherein the preferred form of the alkyl group is as described above. In formula (2), R 21 , R22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 is particularly preferably a hydrogen atom.

[0090] Specific examples of the perinone compound (1) and the perinone compound (2) are shown below, but the present embodiment is not limited thereto. In the following structural formulas, Ph represents a phenyl group.

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] The perinone compounds (2-1) to (2-18) are in an isomeric relationship (cis-isomer and trans-isomer relationship) with the perinone compounds (1-1) to (1-18), respectively. Due to the synthesis method, the perinone compounds tend to give a mixture of isomers. One of the isomers of the mixture can be purified from the mixture according to a known purification method.

[0098] In one embodiment, the undercoat layer contains both perinone compound (1) and perinone compound (2). Whether or not perinone compound (1) and perinone compound (2) are isomers, the mass ratio of perinone compound (1) to perinone compound (2) is preferably perinone compound (1):perinone compound (2)=3:97 to 97:3, more preferably 5:95 to 95:5, and even more preferably 10:90 to 90:10.

[0099] [Polyester resin (1)] The photosensitive layer (charge transport layer in the case of a laminated photosensitive layer) contains at least a polyester resin (1) as a binder resin. The polyester resin (1) is a polyester resin having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4), and a diol unit (B) represented by formula (B). The polyester resin (1) may contain a dicarboxylic acid unit other than the dicarboxylic acid unit (A).The polyester resin (1) may contain a diol unit other than the diol unit (B).

[0100] The dicarboxylic acid unit (A) is at least one selected from the group consisting of a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4).

[0101] [ka]

[0102] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra 202each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 201 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 202 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0103] [ka]

[0104] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 302 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0105] [ka]

[0106] In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0107] Ra in formula (A2) 201 and Ra 202 , Ra in formula (A3) 301 and Ra 302 And Ra of formula (A4) 401 Since the specific and preferred embodiments of are the same, hereinafter, Ra 201 , Ra 202 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0108] The alkyl group having 1 to 10 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of the branched alkyl group having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl group formed by linking these monocyclic alkyl groups.

[0109] The aryl group having 6 to 12 carbon atoms related to Ra may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0110] The alkyl group in the alkoxy group having 1 to 6 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0111] Specific examples of the dicarboxylic acid unit (A2) include the following dicarboxylic acid units (A2-1) to (A2-3), but the dicarboxylic acid unit (A2) is not limited thereto.

[0112] [ka]

[0113] Specific examples of the dicarboxylic acid unit (A3) include the dicarboxylic acid units (A3-1) and (A3-2), but the dicarboxylic acid unit (A3) is not limited thereto.

[0114] [ka]

[0115] Specific examples of the dicarboxylic acid unit (A4) include the following dicarboxylic acid units (A4-1) to (A4-3), but the dicarboxylic acid unit (A4) is not limited thereto.

[0116] [ka]

[0117] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the above specific examples (A2-3), (A3-2) and (A4-3), more preferably contains at least one selected from the group consisting of (A2-3) and (A3-2), and even more preferably contains at least (A2-3).

[0118] The total mass proportion of the dicarboxylic acid units (A2) to (A4) in the polyester resin (1) is preferably 15 mass % or more and 60 mass % or less. When the total mass proportion of the dicarboxylic acid units (A2) to (A4) is 15 mass% or more, the photosensitive layer has good abrasion resistance. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A2) to (A4) is more preferably 20 mass% or more, and further preferably 25 mass% or more. When the total mass proportion of the dicarboxylic acid units (A2) to (A4) is 60 mass% or less, peeling of the photosensitive layer can be suppressed. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A2) to (A4) is more preferably 55 mass% or less, and further preferably 50 mass% or less.

[0119] Examples of the dicarboxylic acid units (A) other than the dicarboxylic acid units (A2) to (A4) include aliphatic dicarboxylic acid (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid) units, alicyclic dicarboxylic acid (e.g., cyclohexanedicarboxylic acid) units, and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The dicarboxylic acid units contained in the polyester resin (1) may be of one type or two or more types.

[0120] The dicarboxylic acid units (A) contained in the polyester resin (1) may be of one type or two or more types. That is, the dicarboxylic acid units (A2) to (A4) contained in the polyester resin (1) may be of one type or two or more types.

[0121] The diol unit (B) is a structural unit represented by the following formula (B).

[0122] [ka]

[0123] In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent; L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 is 0, 1 or 2. Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0124] Ar B1The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0125] Ar B1 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0126] Ar B2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0127] Ar B2 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0128] Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, more preferably 1 to 14 carbon atoms, and even more preferably 1 to 10 carbon atoms.

[0129] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6.

[0130] Rb 1 and Rb 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0131] The diol unit (B) preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8).

[0132] The diol unit (B) more preferably includes at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B4), the diol unit (B5) and the diol unit (B6), It is more preferable that the diol unit (B1), the diol unit (B2), the diol unit (B5) and the diol unit (B6) are contained in the copolymer. It is even more preferable that the diol unit (B1), the diol unit (B2) and the diol unit (B6) are included. It is most preferable that the diol unit (B1) contains at least one selected from the group consisting of the diol unit (B2).

[0133] [ka]

[0134] In formula (B1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0135] Rb 101 The carbon number of the branched alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 101 Specific examples of the aryl group include an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0136] [ka]

[0137] In formula (B2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0138] Rb 102 The carbon number of the linear alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples of the aryl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0139] [ka]

[0140] In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0141] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 213The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0142] [ka]

[0143] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0144] Rb 104 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 or 2, and more preferably 1. 104 Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0145] [ka]

[0146] In formula (B5), Ar 105is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0147] Ar 105 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathylmethyl group, and a phenyl-cyclopentylmethyl group.

[0148] [ka]

[0149] In formula (B6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb 406 , Rb 506, Rb 806 and Rb 906 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0150] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0151] [ka]

[0152] In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0153] [ka]

[0154] In formula (B8), Rb408 , Rb 508 , Rb 808 and Rb 908 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0155] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 201 , Rb 202 , Rb 204 and Rb 205 "Rb 200 " is collectively described as such.

[0156] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably has 1 carbon atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0157] Rb in formula (B1) 401 , Rb in formula (B2) 402 , Rb in formula (B3) 403 , Rb in formula (B4) 404 , Rb in formula (B5) 405 , Rb in formula (B6) 406 , Rb in formula (B7) 407 and Rb of formula (B8) 408 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 "Rb 400 " is collectively referred to as ".

[0158] Rb400 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0159] Rb 400 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0160] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0161] Rb in formula (B1) 501 , Rb in formula (B2) 502 , Rb in formula (B3) 503, Rb in formula (B4) 504 , Rb in formula (B5) 505 , Rb in formula (B6) 506 , Rb in formula (B7) 507 and Rb of formula (B8) 508 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 "Rb 500 " is collectively referred to as ".

[0162] Rb 500 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0163] Rb 500 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0164] Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0165] Rb in formula (B1) 801 , Rb in formula (B2) 802 , Rb in formula (B3) 803 , Rb in formula (B4) 804 , Rb in formula (B5) 805 , Rb in formula (B6) 806 , Rb in formula (B7) 807 and Rb of formula (B8) 808 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 "Rb 800 " is collectively referred to as ".

[0166] Rb 800 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0167] Rb 800 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0168] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0169] Rb in formula (B1) 901 , Rb in formula (B2) 902 , Rb in formula (B3) 903 , Rb in formula (B4) 904 , Rb in formula (B5) 905 , Rb in formula (B6) 906 , Rb in formula (B7) 907 and Rb of formula (B8) 908 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb907 and Rb 908 "Rb 900 " is collectively referred to as ".

[0170] Rb 900 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0171] Rb 900 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0172] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0173] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0174] [ka]

[0175] Specific examples of the diol unit (B2) include the diol units (B2-1) to (B2-11), but the diol unit (B2) is not limited thereto.

[0176] [ka]

[0177] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0178] [ka]

[0179] Specific examples of the diol unit (B4) include the diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0180] [ka]

[0181] Specific examples of the diol unit (B5) include the diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0182] [ka]

[0183] Specific examples of the diol unit (B6) include the diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0184] [ka]

[0185] Specific examples of the diol unit (B7) include diol units (B7-1) to (B7-3), but the diol unit (B7) is not limited thereto.

[0186] [ka]

[0187] Specific examples of the diol unit (B8) include the diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0188] [ka]

[0189] The diol unit (B) contained in the polyester resin (1) may be of one type or of two or more types.

[0190] The mass proportion of the diol unit (B) in the polyester resin (1) is preferably 25 mass % or more and 80 mass % or less. When the mass proportion of the diol unit (B) is 25 mass% or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 30 mass% or more, and further preferably 35 mass% or more. When the mass proportion of the diol unit (B) is 80 mass% or less, the solubility in the coating solution for forming the photosensitive layer can be maintained and the abrasion resistance can be improved. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 75 mass% or less, and further preferably 70 mass% or less.

[0191] Examples of the diol units other than the diol units (B) include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0192] The ends of the polyester resin (1) may be capped or modified with an end-capping agent or a molecular weight regulator used during production. Examples of the end-capping agent or the molecular weight regulator include a monohydric phenol, a monovalent acid chloride, a monohydric alcohol, and a monovalent carboxylic acid. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m -phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, and 2-phenyl-2-(3-hydroxyphenyl)propane. Examples of the monovalent acid chloride include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetic acid chloride, butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and substituted versions of these. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monovalent carboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0193] The weight average molecular weight of the polyester resin (1) is preferably from 30,000 to 300,000, more preferably from 40,000 to 250,000, and even more preferably from 50,000 to 200,000. The molecular weight of the polyester resin (1) is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (GPC), which uses tetrahydrofuran as an eluent.

[0194] The polyester resin (1) can be obtained by polycondensing a monomer that gives a dicarboxylic acid unit (A) and a monomer that gives a diol unit (B) with other monomers as required by a conventional method. Examples of the method for polycondensing a monomer include an interfacial polymerization method, a solution polymerization method, and a melt polymerization method. The interfacial polymerization method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent that is not compatible with water with a dihydric alcohol dissolved in an alkaline aqueous solution. Examples of literature related to the interfacial polymerization method include WME ARECSON, J. Poly. Sci., XL399, 1959, and JP-B-1959. The interfacial polymerization method has a faster reaction rate than the solution polymerization method, and therefore can suppress hydrolysis of the dicarboxylic acid halide, resulting in a polyester resin with a high molecular weight.

[0195] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is less than Ωcm.

[0196] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiating with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate since it suppresses the occurrence of defects due to unevenness on the surface.

[0197] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0198] As a method for roughening the surface, there can be mentioned a method in which, without roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0199] In the roughening treatment by anodization, an oxide film is formed on the surface of a conductive substrate made of metal (e.g., aluminum) by anodizing the substrate in an electrolyte solution using the substrate as the anode. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodization is chemically active in its original state, easily contaminated, and has a large resistance variation depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are filled by volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel may be added) to change the film into a more stable hydrated oxide.

[0200] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm. If the thickness is within this range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0201] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acid treatment liquid is carried out, for example, as follows. First, an acid treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acid treatment liquid are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42° C. to 48° C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0202] 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 the material with heated steam at 90°C to 120°C for 5 to 60 minutes. The thickness of the coating is preferably 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution having low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0203] [Sublayer] The undercoat layer contains at least a binder resin and a perinone compound.

[0204] The binder resin of the undercoat layer is not particularly limited, and known resins can be used.Specific examples thereof include polyvinyl alcohol, polyvinyl acetal, polyethylene oxide, casein, polyamide, polyamic acid, polyurethane, polyimide, cellulose, gelatin, polyester, unsaturated polyester, polyolefin resin, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinyl acetate, 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, hydrolyzable silyl group-containing resin, and hydrolyzable silane condensate.

[0205] The undercoat layer preferably contains at least polyurethane as a binder resin. The mass proportion of polyurethane in the total amount of the binder resin in the undercoat layer is preferably 60 mass % or more, more preferably 70 mass % or more, even more preferably 80 mass % or more, and may be 100 mass %.

[0206] Polyurethanes are generally synthesized by the polyaddition reaction of polyfunctional isocyanates with polyols.

[0207] Examples of polyfunctional isocyanates 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, 3,3'-diisocyanate, Examples of the polyfunctional isocyanate include diisocyanates such as methyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethylbiphenylene diisocyanate, 4,4'-biphenylene diisocyanate, dicyclohexylmethane diisocyanate, and methylene bis(4-cyclohexyl isocyanate); isocyanurates obtained by trimerizing the above diisocyanates; and blocked isocyanates obtained by blocking the isocyanate groups of the above diisocyanates with a blocking agent. One type of polyfunctional isocyanate may be used, or two or more types may be used in combination.

[0208] 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, 2,4-dimethyl-2,4-pentanediol, Examples of diols include hexanediol, 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'-dihydroxy-diphenyl-2,2-propane, and 4,4'-dihydroxyphenyl sulfone. Further examples of the polyol include polyester polyol, polycarbonate polyol, polycaprolactone polyol, polyether polyol, polyvinyl butyral, and the like. The polyol may be used alone or in combination of two or more kinds.

[0209] The undercoat layer may contain components other than the binder resin and the perinone compound. The other components are described below.

[0210] The undercoat layer may contain at least one of an organic acid metal salt and an organic metal complex. At least one of the organic acid metal salt and the organic metal complex contained in the undercoat layer may be, for example, an organic acid metal salt or an organic metal complex that acts as a urethane curing catalyst (i.e., a catalyst for a polyaddition reaction between a polyfunctional isocyanate and a polyol) when the undercoat layer is formed.

[0211] Examples of the metal constituting the organic acid metal salt or the organic metal complex include bismuth, aluminum, zirconium, zinc, cobalt, iron, nickel, copper, tin, platinum, palladium, etc. The organic acid of the organic acid metal salt is preferably a monovalent carboxylic acid, and the monovalent carboxylic acid is preferably octylic acid, naphthenic acid or salicylic acid, and more preferably octylic acid.

[0212] As the at least one kind of organic acid metal salt and organic metal complex contained in the undercoat layer, from the viewpoint of suppressing an increase in residual potential that occurs during repeated image formation, at least one kind of organic acid metal salt and organic metal complex containing a metal selected from the group consisting of bismuth, aluminum, zirconium, zinc, cobalt, iron, nickel and copper is preferred, and at least one kind of organic acid metal salt and organic metal complex containing a metal selected from the group consisting of bismuth, aluminum and zirconium is more preferred.

[0213] Examples of the organic acid metal salt or organometallic complex containing bismuth include bismuth octylate, bismuth naphthenate, bismuth salicylate; K-KAT348, K-KAT XC-C227, K-KAT XK-628, and K-KAT XK-640 manufactured by King Industries, Ltd.; and the like. Examples of the organic acid metal salt or organometallic complex containing aluminum include aluminum octylate, aluminum naphthenate, aluminum salicylate; K-KAT5218 manufactured by King Industries; and the like. Examples of the zirconium-containing organic acid metal salt or organometallic complex include zirconium octylate, zirconium naphthenate, zirconium salicylate; K-KAT4205, K-KAT6212, and K-KATA209 manufactured by King Industries; and the like. Examples of the zinc-containing organic acid metal salt or organometallic complex include zinc octylate, zinc naphthenate, and zinc salicylate. Examples of the cobalt-containing organic acid metal salt or organometallic complex include cobalt octylate, cobalt naphthenate, and cobalt salicylate. Examples of the iron-containing organic acid metal salt or organometallic complex include iron octylate, iron naphthenate, and iron salicylate. Examples of the nickel-containing organic acid metal salt or organometallic complex include nickel octylate, nickel naphthenate, and nickel salicylate. Examples of the copper-containing organic acid metal salt or organometallic complex include copper octylate, copper naphthenate, and copper salicylate.

[0214] The organic acid metal salts and organometallic complexes may be used alone or in combination of two or more kinds.

[0215] When the undercoat layer contains at least one of an organic acid metal salt and an organic metal complex, the total content of the organic acid metal salt and the organic metal complex relative to the total solid content of the undercoat layer is preferably 0.001 mass% or more and 3 mass% or less, more preferably 0.003 mass% or more and 2 mass% or less, even more preferably 0.01 mass% or more and 1 mass% or less, and even more preferably 0.05 mass% or more and 0.5 mass% or less.

[0216] The undercoat layer may contain inorganic particles. The inorganic particles may have a powder resistivity (volume resistivity) of 1×10 2 Ωcm or more 1×10 11 Examples of such particles include inorganic particles with a particle size of Ωcm or less. Examples of inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and among these, zinc oxide particles are preferred. Other examples of inorganic particles include silica particles and metal titanate compound particles. Metal titanate compound particles include strontium titanate particles, barium titanate particles, calcium titanate particles, and magnesium titanate particles.

[0217] The specific surface area of ​​inorganic particles by the BET method is, for example, 10 m 2 / g or higher is preferable. The volume average particle size of the inorganic particles is, for example, from 50 nm to 2000 nm (preferably from 60 nm to 1000 nm).

[0218] The inorganic particles may be surface-treated. Two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0219] Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, etc. A silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0220] 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.

[0221] Silane coupling agents may be used in combination of two or more kinds. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0222] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method. The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

[0223] The undercoat layer preferably contains an electron-accepting compound (acceptor compound) together with inorganic particles, from the viewpoints of improving the long-term stability of electrical properties and carrier blocking properties.

[0224] Examples of the electron-accepting compound include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds. The electron-accepting compound is preferably a compound having an anthraquinone structure. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and more specifically, anthraquinone, alizarin, quinizarin, anthraphin, and purpurin.

[0225] The electron accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surfaces of the inorganic particles.

[0226] The method for attaching the electron accepting compound to the surface of the inorganic particles may be, for example, a dry method or a wet method.

[0227] The dry method is, for example, a method in which an electron-accepting compound is attached to the surface of inorganic particles by dropping an electron-accepting compound directly or dissolved in an organic solvent or spraying it together with dry air or nitrogen gas while stirring inorganic particles with a mixer or the like that exerts a large shearing force. The dropping or spraying of the electron-accepting compound is preferably performed at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100° C. or higher. The temperature and time of baking are not particularly limited as long as electrophotographic properties can be obtained.

[0228] The wet method is a method in which, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and the inorganic particles are stirred or dispersed, and then the solvent is removed to attach the electron-accepting compound to the surface of the inorganic particles. The solvent is removed, for example, by filtration or distillation. After the solvent is removed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound, and examples of such methods include a method of removing the moisture while stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0229] The attachment of the electron accepting compound may be carried out before or after the inorganic particles are subjected to a surface treatment with a surface treatment agent, or the attachment of the electron accepting compound and the surface treatment with the surface treatment agent may be carried out simultaneously.

[0230] The content of the electron accepting compound is preferably from 0.01% by mass to 20% by mass, and more preferably from 0.01% by mass to 10% by mass, based on the inorganic particles.

[0231] The undercoat layer may contain various additives to improve charge retention, electrical properties, environmental stability, and image quality. Examples of additives include known materials such as amine compounds having an ionization potential of 5.4 eV to 5.9 eV, polycyclic condensation and azo electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As described above, silane coupling agents are used for surface treatment of inorganic particles, and may be further added to the undercoat layer as an additive.

[0232] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like.

[0233] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0234] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-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.

[0235] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0236] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0237] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used in order to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, grinding, and the like.

[0238] The formation of the undercoat layer is not particularly limited, and a known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating solution for forming the undercoat layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary.

[0239] Examples of the solvent for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0240] Since the perinone compound (1) and the perinone compound (2) are difficult to dissolve in an organic solvent, it is preferable to disperse them in the organic solvent. Examples of the dispersion method include known methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker. When inorganic particles are blended in the undercoat layer, it is preferable to disperse the inorganic particles in the organic solvent by the same dispersion method.

[0241] Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0242] From the viewpoint of leak resistance, the average thickness of the undercoat layer is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 5 μm or more. The average thickness of the undercoat layer is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, from the viewpoint of suppressing an increase in residual potential during repeated use.

[0243] The average thickness of each layer of the photoreceptor is the arithmetic mean of the values ​​measured using an electromagnetic film thickness meter, and the measurement points are 12 points in total, at 90° intervals in the circumferential direction near the center and both ends.

[0244] [Middle layer] An intermediate layer may further be provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0245] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0246] The formation of the intermediate layer is not particularly limited, and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating solution for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary. The intermediate layer can be formed by any of the usual coating methods, such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating.

[0247] The average thickness of the intermediate layer is preferably 0.1 μm or more and 3 μm or less.

[0248] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may also be a vapor deposition layer of the charge generation material. The vapor deposition layer of the charge generation material is suitable for use with a non-coherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0249] Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0250] 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, at least one selected from the group consisting of hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine is preferable, hydroxygallium phthalocyanine and / or chlorogallium phthalocyanine is more preferable, and hydroxygallium phthalocyanine is even more preferable.

[0251] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include condensed aromatic pigments such as dibromoanthanthrone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and bisazo pigments.

[0252] The above charge generating materials may be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm, but when using a photosensitive layer that is a thin film of 20 μm or less from the viewpoint of resolution, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate, that is, an image defect known as a black spot, is likely to occur. This becomes more noticeable when using a charge generating material that is a p-type semiconductor that is prone to generating dark current, such as trigonal selenium or phthalocyanine pigment.

[0253] In contrast, when n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge generating materials, dark current is unlikely to occur, and image defects called black spots can be suppressed even in thin films. The n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and those that are more likely to pass electrons as carriers than holes are considered to be n-type.

[0254] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, and the like. Examples of binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic dicarboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamide resins, acrylic resins, polyacrylamide resins, polyvinylpyridine resins, cellulose resins, urethane resins, epoxy resins, casein, polyvinyl alcohol resins, polyvinylpyrrolidone resins, etc. Here, "insulating" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0255] The compounding ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 by mass.

[0256] The charge generating layer may contain other known additives.

[0257] The formation of the charge generation layer is not particularly limited, and a known formation method is used, for example, by forming a coating film of a coating solution for forming the charge generation layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary. The formation of the charge generation layer may be performed by vapor deposition of the charge generation material. The formation of the charge generation layer by vapor deposition is particularly suitable when a condensed ring aromatic pigment or a perylene pigment is used as the charge generation material.

[0258] Examples of the solvent for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0259] Examples of methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming a charge generating layer include media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion liquid is dispersed by penetrating a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0260] Examples of a method for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0261] The average thickness of the charge generating layer is preferably from 0.1 μm to 5.0 μm, and more preferably from 0.2 μm to 2.0 μm.

[0262] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin, and may be a layer containing a polymer charge transport material.

[0263] Examples of the charge transport material include electron transporting compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of the charge transport material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0264] Examples of the polymer charge transport material include known chemical substances having charge transport properties, such as poly-N-vinylcarbazole and polysilane. For example, a polyester-based polymer charge transport material is preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0265] Examples of the charge transport material or polymer charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, paragraphs 0078 to 0080 of JP 2021-117377 A, paragraphs 0046 to 0048 of JP 2019-035900 A, paragraphs 0052 to 0053 of JP 2019-012141 A, paragraphs 0122 to 0134 of JP 2021-071565 A, and paragraphs 0122 to 0134 of JP 2021-015223 A Examples of the compounds include those described in paragraphs 0101 to 0110 of JP 2013-097300 A, paragraphs 0116 of WO 2019 / 070003 A, paragraphs 0103 to 0107 of JP 2018-159087 A, and paragraphs 0102 to 0113 of JP 2021-148818 A.

[0266] From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a compound (C1) represented by the following formula (C1), a compound (C2) represented by the following formula (C2), a compound (C3) represented by the following formula (C3), and a compound (C4) represented by the following formula (C4).

[0267] [ka]

[0268] In formula (C1), Ar T1 , Ar T2 and Ar T3 are each independently an aryl group, -C6H4-C(R T4 )=C(R T5)(R T6 ) or -CH-CH=CH-CH=C(R T7 )(R T8 ) R T4 , R T5 , R T6 , R T7 and R T8 R is independently a hydrogen atom, an alkyl group, or an aryl group. T5 and R T6 When is an aryl group, the aryl groups are connected to each other by -C(R 51 )(R 52 )- and / or -C(R 61 )=C(R 62 R may be linked to the ring via a divalent group represented by the formula: 51 , R 52 , R 61 and R 62 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0269] The group in formula (C1) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0270] From the viewpoint of charge mobility, the compound (C1) is preferably an aryl group or -CH-CH=CH-CH=C(R T7 )(R T8 ) is preferred, and a compound (C'1) represented by the following formula (C'1) is more preferred.

[0271] [ka]

[0272] In formula (C'1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132are each independently a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0273] [ka]

[0274] In formula (C2), R T201 , R T202 , R T211 and R T212 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ) R T21 , R T22 , R T23 , R T24 and R T25 R is independently a hydrogen atom, an alkyl group, or an aryl group. T221 and R T222 are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2.

[0275] The group in formula (C2) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0276] From the viewpoint of charge mobility, the compound (C2) is preferably an alkyl group, an aryl group, or a -CH=CH-CH=C(R T24 )(R T25) is preferred, and an alkyl group, an aryl group, or a -CH=CH-CH=C(R T24 )(R T25 ) is more preferred.

[0277] [ka]

[0278] In formula (C3), R T301 , R T302 , R T311 and R T312 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ) R T31 , R T32 , R T33 , R T34 and R T35 R is independently a hydrogen atom, an alkyl group, or an aryl group. T321 , R T322 and R T331 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2.

[0279] The group in formula (C3) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0280] [ka]

[0281] In formula (C4), R T401 , R T402 , R T411 and R T412 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ) R T41 , R T42 , R T43 , R T44 and R T45 R is independently a hydrogen atom, an alkyl group, or an aryl group. T421 , R T422 and R T431 each independently represents a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 each independently represent 0, 1, or 2.

[0282] The group in formula (C4) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0283] The content of the charge transport material in the charge transport layer is preferably 20% by mass or more and 70% by mass or less based on the total mass of the charge transport layer.

[0284] The charge transport layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the charge transport layer is preferably 40% by weight or more, more preferably 50% by weight or more, further preferably 60% by weight or more, and particularly preferably 70% by weight or more.

[0285] When the polyester resin (1) is used in combination with another resin, the other resin is preferably a polycarbonate resin. An example of an embodiment of the charge transport layer contains a polyester resin (1) and a polycarbonate resin as binder resins, and in this case, the mass ratio of the two resins (polyester resin (1):polycarbonate resin) is preferably 95:5 to 30:70, more preferably 95:5 to 40:60. The total mass ratio of the polyester resin (1) and the polycarbonate resin in the charge transport layer is preferably from 15 to 80% by mass, more preferably from 20 to 75% by mass, and even more preferably from 25 to 70% by mass.

[0286] The polycarbonate resin is preferably a polycarbonate resin having continuous structural units having an aromatic ring, and specific examples thereof include the polycarbonate resins used in the examples described below.

[0287] The charge transport layer may contain other binder resins other than the polyester resin (1) and the polycarbonate resin. Examples of other binder resins include polyester resins other than the polyester resin (1), methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilanes, etc. These binder resins are used alone or in combination of two or more.

[0288] The charge transport layer may contain other known additives, such as an antioxidant, a leveling agent, a defoaming agent, a filler, and a viscosity modifier.

[0289] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0290] Examples of solvents for preparing the coating liquid for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination of two or more.

[0291] Examples of a coating method for coating the coating liquid for forming the charge transport layer on the charge generating layer include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating and curtain coating.

[0292] The average thickness of the charge transport layer is preferably 20 μm or more, more preferably 22 μm or more, and even more preferably 25 μm or more, from the viewpoints of the photosensitivity and wear life of the photoreceptor. The average thickness of the charge transport layer is preferably 50 μm or less, more preferably 47 μm or less, and even more preferably 45 μm or less, from the viewpoint of residual potential.

[0293] [Single-layer photosensitive layer] The single-layer photosensitive layer (charge generation / transport layer) is a layer containing a charge generation material, a charge transport material, a binder resin, and other additives as necessary. These materials are the same as those described for the charge generation layer and the charge transport layer.

[0294] The single-layer type photosensitive layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the single-layer photosensitive layer is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0295] When the polyester resin (1) is used in combination with another resin, the other resin is preferably a polycarbonate resin. An example of an embodiment of the single-layer type photosensitive layer contains a polyester resin (1) and a polycarbonate resin as binder resins. In this case, the mass ratio of the two resins, polyester resin (1):polycarbonate resin, is preferably 95:5 to 30:70, and more preferably 95:5 to 40:60. The total mass proportion of the polyester resin (1) and the polycarbonate resin in the single-layer photosensitive layer is preferably from 15 to 80% by mass, more preferably from 20 to 75% by mass, and even more preferably from 25 to 70% by mass.

[0296] The polycarbonate resin is preferably a polycarbonate resin having continuous structural units having an aromatic ring, and specific examples thereof include the polycarbonate resins used in the examples described below.

[0297] In the single-layer photosensitive layer, the content of the charge generating material is preferably from 0.1% by mass to 10% by mass, more preferably from 0.8% by mass to 5% by mass, based on the total solid content.

[0298] The content of the charge transport material in the single-layer photosensitive layer is preferably 40% by mass or more and 60% by mass or less based on the total solid content.

[0299] The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer.

[0300] The average thickness of the single-layer photosensitive layer is preferably 20 μm or more, more preferably 22 μm or more, and even more preferably 25 μm or more, from the viewpoints of the photosensitivity and wear life of the photoreceptor. The average thickness of the single-layer photosensitive layer is preferably 50 μm or less, more preferably 47 μm or less, and even more preferably 45 μm or less, from the viewpoint of residual potential.

[0301] [Protective layer] A protective layer is provided on the photosensitive layer as necessary for the purpose of, for example, preventing chemical changes in the photosensitive layer when the photosensitive layer is charged and further improving the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a layer composed of a cured film (crosslinked film) as the protective layer. Examples of such a layer include the following layers 1) and 2).

[0302] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer containing a polymer or crosslinked product of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material that does not have a charge transport skeleton and has a reactive group (i.e., a layer containing a non-reactive charge transport material and a polymer or crosslinked body of the reactive group-containing non-charge transport material).

[0303] The reactive group of the reactive group-containing charge transport material may be a chain polymerizable group, an epoxy group, -OH, -OR (wherein R represents an alkyl group), -NH2, -SH, -COOH, or -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group; R Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group; Qn represents an integer of 1 to 3.

[0304] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond.Specific examples include a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof.Among them, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof, because of its excellent reactivity.

[0305] 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, and examples thereof include a skeleton derived from a nitrogen-containing hole transporting compound such as a triarylamine compound, a benzidine compound, a hydrazone compound, etc., and a structure conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0306] The reactive group-containing charge transport material having a reactive group and a charge transporting skeleton, the non-reactive charge transport material, and the reactive group-containing non-charge transport material may be selected from known materials.

[0307] The protective layer may contain other known additives.

[0308] The formation of the protective layer is not particularly limited, and a known formation method can be used. For example, the protective layer can be formed by forming a coating film of a coating liquid for forming a protective layer in which the above components are added to a solvent, drying the coating film, and, if necessary, subjecting it to a curing treatment such as heating.

[0309] Examples of solvents for preparing a coating solution 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 may be used alone or in combination of two or more. The coating liquid for forming the protective layer may be a solvent-free coating liquid.

[0310] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (e.g., a charge transport layer) include conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0311] The average thickness of the protective layer is preferably from 1 μm to 20 μm, and more preferably from 2 μm to 10 μm.

[0312] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging device that charges the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device that develops 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 device that transfers the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

[0313] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus including a fixing device that fixes a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type that directly transfers a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type that primarily transfers a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member, and then secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus including a cleaning device that cleans the surface of an electrophotographic photosensitive member before charging after the transfer of a toner image; an apparatus including a static elimination device that irradiates the surface of an electrophotographic photosensitive member with static elimination light to eliminate static electricity before charging after the transfer of a toner image; and an apparatus including an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0314] In the case of an intermediate transfer type device, the transfer device is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer device which primarily transfers the toner image formed on the surface of an electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer device which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0315] The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0316] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. The process cartridge may include, in addition to the electrophotographic photosensitive member, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0317] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Principal parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0318] FIG. 3 is a schematic diagram showing an example of an image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), 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 disposed at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, and the intermediate transfer body 50 is disposed with a part of it in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 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 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer device.

[0319] 3 supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) integrally within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0320] FIG. 3 shows an example of an image forming apparatus including a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of the electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists in cleaning, which are arranged as needed.

[0321] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0322] -Charging device- As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also, a non-contact type roller charger, a scorotron charger or corotron charger that utilizes corona discharge, or other chargers known per se, can be used.

[0323] -Exposure equipment- The exposure device 9 may be, for example, an optical device that exposes the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. The wavelength of the semiconductor laser is mainly near infrared light having an oscillation wavelength of about 780 nm. However, it is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a blue laser having an oscillation wavelength of 400 nm to 450 nm may also be used. In addition, a surface-emitting laser light source capable of outputting multiple beams is also effective for forming a color image.

[0324] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contacting or non-contacting a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected according to the purpose. For example, it may be a known developing device that has a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, roller, or the like. Among them, it is preferable to use a developing roller that holds a developer on its surface.

[0325] The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Known developers are used.

[0326] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning type or a simultaneous development and cleaning type may also be adopted.

[0327] -Transfer device- Examples of the transfer device 40 include known transfer chargers such as a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0328] -Intermediate transfer body- A belt-like intermediate transfer belt containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. is used as the intermediate transfer body 50. The intermediate transfer body may be in the form of a drum other than a belt.

[0329] FIG. 4 is a schematic diagram showing another example of the image forming apparatus according to the present embodiment. 4 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photosensitive body 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

[0330] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, unless otherwise specified, synthesis, production, processing, measurement, etc. were carried out at room temperature (25° C.±3° C.).

[0331] <Synthesis of polyester resin (1)> Polyester resins (1-1) to (1-6) were synthesized. In the synthesis of all of these resins, polymerization was carried out in the presence of an end-capping agent, 4-tert-butylphenol, to cap the ends of the polyester resins. Table 1 shows the units and composition of the polyester resin (1). A2-3 and the like shown in Table 1 are specific examples of the above-mentioned dicarboxylic acid unit (A). B1-4 and the like shown in Table 1 are specific examples of the diol unit (B) described above.

[0332] [Table 1]

[0333] <Production of a photoreceptor having a laminated photosensitive layer> [Example S1] - Formation of undercoat layer - As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm was prepared.

[0334] 20 parts of blocked isocyanate (Sumidur BL3175, manufactured by Sumitomo Bayern Urethane Co., Ltd., solid content 75%) and 7.5 parts of butyral resin (polyvinyl butyral, S-LEC BL-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 150 parts of methyl ethyl ketone. 34 parts of a mixture (mass ratio 50:50) of perinone compound (1-1) and perinone compound (2-1) were mixed with this solution, and dispersed for 10 hours in a sand mill using glass beads with a diameter of 1 mm to obtain a dispersion. 0.005 parts of bismuth carboxylate (K-KAT XK-640, manufactured by King Industries Co., Ltd.) and 2 parts of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials Co., Ltd.) were added to this dispersion to obtain a coating liquid for forming an undercoat layer. This coating liquid was applied by immersion onto a conductive substrate, and dried and cured at 160°C for 60 minutes to form an undercoat layer. The average thickness of the undercoat layer is shown in Table 2.

[0335] - Formation of charge generation layer - A mixture of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generating material, 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating liquid for forming a charge generating layer. This coating liquid was dip-coated on the undercoat layer and dried at room temperature to form a charge generating layer with an average thickness of 0.18 μm.

[0336] - Formation of charge transport layer - 17 parts of polyester resin (1-1) and 43 parts of polycarbonate resin (1) as binder resins, and 40 parts of CTM-1 as charge transport material were dissolved in 270 parts of tetrahydrofuran and 30 parts of toluene to obtain a coating liquid for forming a charge transport layer. This coating liquid was dip-coated on the charge generation layer and dried at 145°C for 30 minutes to form a charge transport layer with an average thickness of 34 μm.

[0337] [ka]

[0338] [ka]

[0339] [Examples S2 to S23, Comparative Examples SC1 to SC4] Each photoreceptor was prepared in the same manner as in Example S1, except that the type and mass ratio of the binder resin in the undercoat layer, the type and mass ratio of the perinone compound in the undercoat layer, the type of organic acid metal salt or organometallic complex in the undercoat layer, the average thickness of the undercoat layer, the type of charge generating material in the charge generating layer, the type and mass ratio of the binder resin in the charge transport layer, the type and mass ratio of the charge transport material in the charge transport layer, and the average thickness of the charge transport layer were changed to the specifications shown in Tables 2 and 3.

[0340] In Example S8, the solvent of the coating liquid for forming the undercoat layer was changed from methyl ethyl ketone to a mixed solvent of isopropanol and water (mass ratio 60:40).

[0341] The polyolefin (1) used in Example S8 is a resin obtained by hydrolyzing the maleic anhydride portion of Bondine HX-8290 (Sumitomo Chemical Co., Ltd., ethylene-acrylic acid ester-maleic anhydride terpolymer) to form a triethylamine salt. Specifically, it was synthesized as follows. In a reaction vessel, 75 parts of Bondine HX-8290, 90 parts of isopropanol, 1.2 times the equivalent of triethylamine relative to the carboxyl group of maleic anhydride in the resin, and 200 parts of distilled water were charged and heated at 145° C. for 60 minutes while stirring. Then, the mixture was cooled to room temperature while stirring, and pressure-filtered through a 300-mesh stainless steel filter to obtain an aqueous dispersion of polyolefin (1) with a solid content concentration of 20%.

[0342] In Example S9, the solvent of the coating liquid for forming the undercoat layer was changed from methyl ethyl ketone to a mixed solvent of methanol and isopropanol (mass ratio 70:30). The polyamide (1) used in Example S9 was CM8000 (Toray Industries, Inc.).

[0343] The "hydroxy Ga phthalocyanine" described in Tables 3 and 6 is hydroxygallium phthalocyanine. The "Ti phthalocyanine" in Table 3 is titanyl phthalocyanine. The imide compound (A), polyester resin (C1) and charge transport materials CTM-2 to CTM-4 are the following compounds, respectively.

[0344] [ka]

[0345] [ka]

[0346] [ka]

[0347] <Production of a photoreceptor having a single-layer type photosensitive layer> [Photoconductor T1] - Formation of undercoat layer - An undercoat layer was formed on the conductive substrate in the same manner as in Example S1. The average thickness of the undercoat layer is shown in Table 5.

[0348] - Formation of a single-layer photosensitive layer - 52.75 parts of polyester resin (1-1) as a binder resin, 1.25 parts of V-type hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in the X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generating material, 7.8 parts of ETM-1 as an electron transport material, 38.2 parts of CTM-1 as a charge transport material (mass ratio of ETM-1 to CTM-1: 17:83), 175 parts of tetrahydrofuran and 75 parts of toluene as a solvent were mixed, and dispersion treatment was performed for 4 hours using a sand mill with glass beads having a diameter of 1 mm to obtain a coating liquid for forming a photosensitive layer. This coating liquid was dip-coated on the undercoat layer, and dried and cured at a temperature of 110° C. for 40 minutes to form a single-layer type photosensitive layer with an average thickness of 34 μm.

[0349] [ka]

[0350] [Photoconductor T2~T6, Photoconductor TC1~TC3] Each photoreceptor was produced in the same manner as photoreceptor T1, except that the type of binder resin in the undercoat layer, the type of perinone compound in the undercoat layer, the type of binder resin in the single-layer photosensitive layer, the type of charge transport material in the single-layer photosensitive layer, and the average thickness of the single-layer photosensitive layer were changed to the specifications shown in Tables 5 and 6.

[0351] <Photoreceptor performance evaluation> The photoreceptor of each of the examples and comparative examples was mounted on an image forming apparatus Apeos C7070 manufactured by FUJIFILM Business Innovation Co., Ltd. To measure the surface potential of the photoreceptor, a probe connected to a surface potential meter (Trek 334, manufactured by Trek Corporation) was placed at the center of the photoreceptor and 1 mm away from the surface of the photoreceptor. In an environment of 28° C. temperature and 85% relative humidity, the charging conditions and exposure conditions were adjusted for the photoconductor of Example S5 (before printing evaluation) so that the charging potential and the potential after exposure became the following settings A and B. For the other photoconductors, the printing evaluation described below was performed under the same charging conditions and exposure conditions. Setting A: Surface potential after charging is -700V, and surface potential after exposure is -240V Setting B: Surface potential after charging is -800V, and surface potential after exposure is -210V

[0352] [Charged potential maintenance] In an environment with a temperature of 28°C and a relative humidity of 85%, 70,000 full-page halftone images with an image density of 30% were printed on A3-sized paper using setting A and setting B. The difference in charge potential between the first sheet printed and the 70,000th sheet printed was calculated and classified as follows. The evaluation results are shown in Tables 4 and 7. A: The difference in charged potential is less than 20V B: The difference in charged potential is 20V or more and less than 30V C: The difference in charged potential is 30V or more and less than 40V D: The difference in charged potential is 40V or more and less than 50V E: The difference in charged potential is 50V or more

[0353] [Maintenance of potential after exposure] In an environment with a temperature of 28°C and a relative humidity of 85%, 70,000 full-page halftone images with an image density of 30% were printed on A3 size paper using setting A and setting B. The difference in residual potential after the first sheet was printed and exposed and the 70,000th sheet was printed and exposed was calculated and classified as follows. The evaluation results are shown in Tables 4 and 7. A: The difference in residual potential is less than 30V B: The difference in residual potential is 30V or more and less than 40V C: Residual potential difference is 40V or more and less than 50V D: Residual potential difference is 50V or more and less than 60V E: Residual potential difference is 60V or more

[0354] [Burned-in ghost] In an environment with a temperature of 28°C and a relative humidity of 85%, 30,000 sheets of the grid-like chart image (cyan color) shown in Figure 5(A) were printed on A3 size paper using setting A and setting B, and then one full-surface halftone image (cyan color) with an image density of 20% was continuously output. The appearance of the grid-like image (burn-in ghost) on the full-surface halftone image was visually observed and classified as follows. The evaluation results are shown in Tables 4 and 7. A: As shown in Figure 5(B), no lattice image is observed. B: As in Figure 5(C), a faint grid-like image can be seen. C: As in Figure 5(D), a grid-like image is clearly visible.

[0355] [Table 2]

[0356] [Table 3]

[0357] [Table 4]

[0358] [Table 5]

[0359] [Table 6]

[0360] [Table 7]

[0361] The electrophotographic photoreceptor, process cartridge, and image forming apparatus of the present disclosure include the following aspects: Each formula is the same as the formula with the same number described above.

[0362] (((1))) A conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer, the undercoat layer contains a binder resin and at least one perinone compound selected from the group consisting of compounds represented by formula (1) and compounds represented by formula (2), the photosensitive layer contains a polyester resin (1) having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4), and a diol unit (B) represented by formula (B), The mass ratio of the polyester resin (1) in the photosensitive layer is 15 mass% or more. Electrophotographic photoreceptor. (((2))) The electrophotographic photoreceptor according to (((1))), wherein the mass ratio of the perinone compound in the undercoat layer is 30 mass % or more and 90 mass % or less. (((3))) The electrophotographic photoreceptor according to (((1))) or (((2))), wherein the undercoat layer contains polyurethane. (((4))) The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein the average thickness of the undercoat layer is 5 μm or more and 30 μm or less. (((5))) The electrophotographic photoreceptor according to any one of (((1))) to (((4))), wherein the photosensitive layer further contains a polycarbonate resin. (((6))) The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein the polyester resin (1) has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8). (((7))) The electrophotographic photoreceptor according to any one of (((1))) to (((6))), wherein the photosensitive layer contains gallium phthalocyanine as a charge generating material. (((8))) An electrophotographic photoreceptor according to any one of (((1))) to (((7))), A process cartridge that is detachably attached to an image forming apparatus. (((9))) An electrophotographic photoreceptor according to any one of (((1))) to (((7))), a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

[0363] According to the invention related to (((1))), (((3))), (((5))), (((6))) or (((7))), there is provided an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur in the image, compared to when the mass ratio of polyester resin (1) in the photosensitive layer is less than 15 mass %, and these are realized over a relatively wide setting range of charging and exposure intensity. The invention related to (((2))) provides an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur, compared with cases in which the mass ratio of the perinone compound in the undercoat layer is less than 30 mass % or more than 90 mass %, and which realizes these properties over a relatively wide setting range of charging and exposure intensity. According to the invention related to (((4))), there is provided an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur, compared with cases in which the average thickness of the undercoat layer is less than 5 μm or more than 30 μm, and these characteristics are realized over a relatively wide setting range of charging and exposure intensity. According to the invention related to (((8))), there is provided a process cartridge equipped with an electrophotographic photosensitive member in which the difference in electrical properties between the beginning and end of repeated image formation is small and ghost images are less likely to occur compared to when the mass ratio of polyester resin (1) in the photosensitive layer is less than 15 mass %, and these are realized over a relatively wide setting range of charging and exposure intensity. According to the invention related to (((9))), there is provided an image forming apparatus equipped with an electrophotographic photoreceptor in which the difference in electrical properties between the initial and final stages of repeated image formation is small and image burn-in ghosts are less likely to occur, compared to when the mass ratio of polyester resin (1) in the photosensitive layer is less than 15 mass %, and these are realized over a relatively wide setting range of charging and exposure intensity. [Explanation of symbols]

[0364] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0365] 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming apparatus, 120 image forming apparatus, 131 cleaning blade, 132 fibrous member (roll-shaped), 133 fibrous member (flat brush-shaped), 300 process cartridge

Claims

1. A conductive substrate, an undercoat layer disposed on the conductive substrate, and a photosensitive layer disposed on the undercoat layer, the undercoat layer contains a binder resin and at least one perinone compound selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), the photosensitive layer contains a polyester resin (1) having at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4), and a diol unit (B) represented by the following formula (B): The mass ratio of the polyester resin (1) in the photosensitive layer is 15 mass% or more. Electrophotographic photoreceptor. 【Chemistry 1】 In formula (1), R １１ , R １２ , R １３ , R １４ , R １５ , R １６ , R １７ and R １８ R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. １１ and R １２ , R １２ and R １３ and R １３ and R １４ may each independently be linked to each other to form a ring. １５ and R １６ , R １６ and R １７ and R １７ and R １８ may each independently be linked to each other to form a ring. In formula (2), R ２１ , R ２２ , R ２３ , R ２４ , R ２５ , R ２６ , R ２７ and R ２８ R each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonylalkyl group, an aryloxycarbonylalkyl group, or a halogen atom. ２１ and R ２２ , R ２２ and R ２３ and R ２３ and R ２４ may each independently be linked to each other to form a ring. ２５ and R ２６ , R ２６ and R ２７ and R ２７ and R ２８ may each independently be linked to each other to form a ring. 【Chemistry 2】 In formula (A2), n ２０１ and n ２０２ are each independently an integer of 0 to 4, ２０１ Ra ２０１ and n ２０２ Ra ２０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (B), Ar Ｂ１ and Ar Ｂ２ each independently represents an aromatic ring which may have a substituent; L Ｂ is a single bond, an oxygen atom, a sulfur atom or -C(Rb １ )(Rb ２ )-, n Ｂ１ is 0, 1 or 2. １ and Rb ２ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb １ and Rb ２ may be bonded to form a cyclic alkyl group.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the mass ratio of the perinone compound in the undercoat layer is from 30% by mass to 90% by mass.

3. The electrophotographic photoreceptor according to claim 1 , wherein the undercoat layer comprises a polyurethane.

4. 2. The electrophotographic photoreceptor according to claim 1, wherein the average thickness of the undercoat layer is from 5 [mu]m to 30 [mu]m.

5. 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer further contains a polycarbonate resin.

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

7. 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer contains gallium phthalocyanine as a charge generating material.

8. The electrophotographic photoreceptor according to any one of claims 1 to 7 is provided, A process cartridge that is detachably attached to an image forming apparatus.

9. The electrophotographic photoreceptor according to any one of claims 1 to 7, a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

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