Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in wear resistance and reduces the occurrence of filming.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate, and a laminated photosensitive layer having a charge generating layer and a charge transport layer. The charge transport layer contains a charge transport material, and at least one of polyester resin and polycarbonate resin having a constitutional unit including biphenyl represented by the formula (1). The charge transport layer has an acid value of 2 mgKOH / g or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the photosensitive layer containing a polyarylate resin having a carboxylic acid terminal value of 100 μequivalents / g or more and 500 μequivalents / g or less and a triphenylamine compound.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor that includes a conductive substrate and a laminated photosensitive layer having a charge generation layer and a charge transport layer, in which the charge transport layer contains a charge transport material, at least one of a polyester resin having a structural unit with an aromatic ring and a polycarbonate resin having a structural unit with an aromatic ring, and a compound represented by a predetermined chemical formula and having a melting point of 40°C or higher. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-209221 [Patent Document 2] Japanese Patent Application Publication No. 2023-121554 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide an electrophotographic photoreceptor that is excellent in abrasion resistance and is less susceptible to filming. [Means for solving the problem]

[0006] 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.

[0007] <1> a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the conductive substrate; the charge transport layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by formula (1), the acid value of the charge transport layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. <2> the mass ratio of the charge transport material in the charge transport layer is 30 mass % or more and 50 mass % or less; <1> The electrophotographic photoreceptor according to claim 1. <3> the polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by formula (1-A) and a diol unit (1-B) represented by formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by formula (1-C): <1> or <2> The electrophotographic photoreceptor according to claim 1. <4> A conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), the acid value of the single-layer photosensitive layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. <5> the mass ratio of the charge transport material in the single-layer photosensitive layer is 40 mass % or more and 60 mass % or less; <4> The electrophotographic photoreceptor according to claim 1. <6> the polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by formula (1-A) and a diol unit (1-B) represented by formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by formula (1-C): <4> or <5> The electrophotographic photoreceptor according to claim 1. <7> <1> ~ <6> The electrophotographic photoreceptor according to any one of the above items is provided, A process cartridge that is detachably attached to an image forming apparatus. <8> <1> ~ <6> an electrophotographic photoreceptor according to any one of the above items; a charging device that charges the surface of the electrophotographic photosensitive member; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image; a transfer device that transfers the toner image onto a surface of a recording medium; An image forming apparatus comprising: [Effects of the Invention]

[0008] <1> , <2> or <3> According to the present invention, an electrophotographic photoreceptor having a laminated photosensitive layer is provided, which has excellent abrasion resistance and is less susceptible to filming compared to an electrophotographic photoreceptor having a charge transport layer with an acid value of more than 2 mgKOH / g. <4> , <5> or <6> According to the present invention, an electrophotographic photoreceptor is provided which has a single-layer photosensitive layer, and which has excellent abrasion resistance and is less susceptible to filming compared to an electrophotographic photoreceptor having a single-layer photosensitive layer with an acid value of more than 2 mgKOH / g. <7> According to the present invention, a process cartridge is provided that includes an electrophotographic photosensitive member that is superior in abrasion resistance and less susceptible to filming compared to an electrophotographic photosensitive member having a charge transport layer of a laminated type photosensitive layer or a single-layer type photosensitive layer with an acid value of more than 2 mgKOH / g. <8> According to the present invention, an image forming apparatus is provided that includes an electrophotographic photosensitive member that is superior in abrasion resistance and less susceptible to filming compared to an electrophotographic photosensitive member having a charge transport layer of a laminated photosensitive layer or a single-layer photosensitive layer with an acid value of more than 2 mgKOH / g. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photosensitive member according to the first embodiment. [Figure 2] FIG. 6 is a partial cross-sectional view showing an example of a layer structure of an electrophotographic photosensitive member according to a second embodiment. [Figure 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. 10 is a schematic configuration diagram illustrating another example of an image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0011] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0012] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0013] 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.

[0014] When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0015] In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0016] In the present disclosure, alkyl groups and alkylene groups include any of linear, branched and cyclic groups, unless otherwise specified. In the present disclosure, a hydrogen atom in an organic group, aromatic ring, linking group, alkyl group, alkylene group, aryl group, aralkyl group, alkoxy group, aryloxy group, or the like may be substituted with a halogen atom.

[0017] In the present disclosure, when a compound is represented 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.

[0018] In the present disclosure, the term "structural unit" of a copolymer or resin has the same meaning as a monomer unit.

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

[0020] The photoreceptor according to the first embodiment includes a conductive substrate and a laminated photoreceptor layer having a charge generating layer and a charge transport layer disposed on the conductive substrate. The photoreceptor according to the first embodiment may further include other layers (for example, an undercoat layer, an intermediate layer).

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

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

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

[0024] In the photoreceptor according to the first embodiment, the charge transport layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), and the acid value of the charge transport layer is 2 mgKOH / g or less.

[0025] In the photoreceptor according to the second embodiment, the single-layer photosensitive layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), and the acid value of the single-layer photosensitive layer is 2 mgKOH / g or less.

[0026] [ka]

[0027] In formula (1), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group.

[0028] The biphenyl represented by formula (1) may be the entire structure or a part thereof obtained by removing an ester bond (-C(=O)O-) or a carbonate bond (-OC(=O)O-) from a structural unit containing the biphenyl represented by formula (1). In other words, the right end and the left end of the biphenyl represented by formula (1) may each independently be bonded directly to an ester bond or a carbonate bond, or may be bonded to an ester bond or a carbonate bond via another atom or atomic group.

[0029] Hereinafter, when matters common to the first and second embodiments are described, both forms will be collectively referred to as the present embodiment.

[0030] The photoreceptor according to this embodiment has excellent abrasion resistance and is less susceptible to filming. The mechanism behind this is presumed to be as follows. In the following description, the charge transport layer of the multi-layer photosensitive layer and the single-layer photosensitive layer are collectively referred to as the "photosensitive layer."

[0031] A photosensitive layer containing at least one of a polyester resin and a polycarbonate resin as a binder resin, each of which has a structural unit containing a biphenyl represented by formula (1), has a strong cohesive force between the binder resins due to the stacking effect between the biphenyls represented by formula (1), thereby improving the abrasion resistance of the photosensitive layer. However, the excellent abrasion resistance of the photosensitive layer inhibits refreshing of the photoreceptor surface, and toner components may adhere to the surface, causing filming. The photoreceptor according to this embodiment has a low acid value in the photosensitive layer, i.e., the content of acid groups in the photosensitive layer is reduced, thereby suppressing the adhesion of substances that react with or are attracted to acid groups, which is presumably why filming is less likely to occur on the surface of the photoreceptor.

[0032] In the photoreceptor according to the first embodiment, from the viewpoint of suppressing the occurrence of filming, it is preferable that the acid value of the charge transport layer is as low as possible, and the acid value of the charge transport layer is 2 mg KOH / g or less, preferably 1.5 mg KOH / g or less, and more preferably 1 mg KOH / g or less.

[0033] In the photoreceptor according to the second embodiment, from the viewpoint of suppressing the occurrence of filming, it is preferable that the acid value of the single-layer photosensitive layer is as low as possible, and the acid value of the single-layer photosensitive layer is 2 mgKOH / g or less, preferably 1.5 mgKOH / g or less, and more preferably 1 mgKOH / g or less.

[0034] The acid value of the charge transport layer or the single-layer photosensitive layer can be adjusted by the following means. When polymerizing a polyester resin or a polycarbonate resin used as a binder resin for a charge transport layer or a single-layer photosensitive layer, measures such as using an appropriate amount of an end-capping agent, increasing the purity of the raw material monomer, starting the polymerization reaction after the monomer is sufficiently dissolved, or setting the concentration of dicarboxylic acid (specifically, dicarboxylic acid chloride) or phosgene in the polymerization reaction system to a low level can be mentioned.

[0035] The acid value of the charge transport layer or the single-layer photosensitive layer is measured as follows: In the following description, the charge transport layer of the multi-layer photosensitive layer and the single-layer photosensitive layer are collectively referred to as "photosensitive layer".

[0036] Peel off the photosensitive layer from the photoreceptor and weigh out 500 mg. Mix 500 mg of the photosensitive layer with 20 mL of tetrahydrofuran and stir thoroughly to dissolve or disperse the components of the photosensitive layer in tetrahydrofuran. This will be used as the titration sample. Using an automatic potentiometric titrator, add 0.01 mL of 0.005 mol / L potassium hydroxide-isopropyl alcohol solution to the titration sample in increments, creating a titration curve. The inflection point on the titration curve is set as the endpoint, and the titration volume up to the endpoint is determined. The acid value of the photosensitive layer (mgKOH / g) is calculated from the titration volume and the mass (500 mg) of the photosensitive layer used in the titration.

[0037] The polyester resin and polycarbonate resin having a structural unit containing biphenyl represented by formula (1) will be described in detail below.

[0038] [Polyester resin (1)] In the present disclosure, a polyester resin having a structural unit containing biphenyl represented by formula (1) is referred to as polyester resin (1).

[0039] [ka]

[0040] In formula (1), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group.

[0041] j is an integer of 0 or more and 4 or less, preferably an integer of 0 or more and 3 or less, more preferably an integer of 0 or more and 2 or less, further preferably 0 or 1, and particularly preferably 0. When j is an integer equal to or greater than 1, j R 11 are each independently a methyl group or an ethyl group, and are preferably a methyl group.

[0042] k is an integer of 0 or more and 4 or less, preferably an integer of 0 or more and 3 or less, more preferably an integer of 0 or more and 2 or less, even more preferably 0 or 1, and particularly preferably 0. When k is an integer equal to or greater than 1, k R 12 are each independently a methyl group or an ethyl group, and are preferably a methyl group.

[0043] From the viewpoint of having a structural unit containing biphenyl represented by formula (1) in the molecule, polyester resin (1) preferably has at least one of a dicarboxylic acid unit (1-A) represented by formula (1-A) below and a diol unit (1-B) represented by formula (1-B) below, and more preferably has a dicarboxylic acid unit (1-A) represented by formula (1-A).

[0044] [ka]

[0045] In formula (1-A), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group, and L A is a single bond or a divalent linking group, and Ar A is an aromatic ring which may have a substituent, and n A is 0, 1 or 2.

[0046] j, k, and R in formula (1-A) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R 12 The specific and preferred embodiments are also the same.

[0047] L A When is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Ra 1 )(Ra 2)-, where Ra 1 and Ra 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; 1 and Ra 2 may be bonded to form a cyclic alkyl group.

[0048] Ra 1 and Ra 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0049] Ra 1 and Ra 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0050] Ra 1 and Ra 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0051] Ar A The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred. Ar AThe hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. A 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.

[0052] [ka]

[0053] In formula (1-B), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group, and L B is a single bond or a divalent linking group, and Ar B is an aromatic ring which may have a substituent, and n B is 0, 1 or 2.

[0054] j, k, and R in formula (1-B) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R 12 The specific and preferred embodiments are also the same.

[0055] L B When Rb is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Rb 1 )(Rb 2 )-, where Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0056] Rb1 and Rb 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0057] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0058] 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.

[0059] Ar B The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred. Ar B The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B 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.

[0060] The dicarboxylic acid unit (1-A) represented by the formula (1-A) is preferably a dicarboxylic acid unit (11-A) represented by the following formula (11-A). The diol unit (1-B) represented by the formula (1-B) is preferably a diol unit (11-B) represented by the following formula (11-B).

[0061] [ka]

[0062] In formula (11-A), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group. In formula (11-B), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group.

[0063] j, k, and R in equation (11-A) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R 12 The specific and preferred embodiments are also the same. j, k, and R in equation (11-B) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R 12 The specific and preferred embodiments are also the same.

[0064] Specific examples of the dicarboxylic acid unit (1-A) include the following dicarboxylic acid units (1-A1) to (1-A10): The dicarboxylic acid unit (1-A) is not limited thereto.

[0065] [ka]

[0066] The dicarboxylic acid unit (1-A) is preferably at least one selected from the group consisting of dicarboxylic acid units (1-A3) to (1-A7), more preferably at least one selected from the group consisting of dicarboxylic acid units (1-A3) to (1-A6), and even more preferably the dicarboxylic acid unit (1-A3).

[0067] Specific examples of the diol unit (1-B) include the following diol units (1-B1) to (1-B10): The diol unit (1-B) is not limited thereto.

[0068] [ka]

[0069] The diol unit (1-B) is preferably at least one selected from the group consisting of diol units (1-B3) to (1-B7), more preferably at least one selected from the group consisting of diol units (1-B3) to (1-B6), and even more preferably the diol unit (1-B3).

[0070] The total mass proportion of the biphenyl-containing structural units represented by formula (1) in polyester resin (1) is preferably 15% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 55% by mass or less, and even more preferably 25% by mass or more and 50% by mass or less.

[0071] The polyester resin (1) may have a structural unit other than the biphenyl-containing structural unit represented by formula (1). The structural unit other than the biphenyl-containing structural unit represented by formula (1) will be described below.

[0072] The polyester resin (1) may have at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A1) represented by the following formula (A1), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4).

[0073] When the polyester resin (1) has a dicarboxylic acid unit (A), the dicarboxylic acid unit (A) may be one type or two or more types. The dicarboxylic acid unit (A) is preferably at least one type selected from the group consisting of a dicarboxylic acid unit (A3) and a dicarboxylic acid unit (A4).

[0074] [ka]

[0075] In formula (A1), n 101 is an integer between 0 and 4, and n 101 Ra 101 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 101 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0076] [ka]

[0077] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301is 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.

[0078] [ka]

[0079] In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401 is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0080] Ra in formula (A1) 101 , Ra in formula (A3) 301 and Ra 302 and Ra in formula (A4) 401 Since the specific and preferred embodiments of Ra are the same as those of 101 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0081] The alkyl group having 1 to 10 carbon atoms represented by Ra may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of branched alkyl groups having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0082] The aryl group having 6 to 12 carbon atoms for Ra may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0083] The alkyl group in the alkoxy group having 1 to 6 carbon atoms, represented by Ra, may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0084] Specific examples of the dicarboxylic acid unit (A1) include dicarboxylic acid units (A1-1) to (A1-9), but the dicarboxylic acid unit (A1) is not limited thereto.

[0085] [ka]

[0086] Specific examples of the dicarboxylic acid unit (A3) include dicarboxylic acid units (A3-1) and (A3-2), but the dicarboxylic acid unit (A3) is not limited thereto.

[0087] [ka]

[0088] Specific examples of the dicarboxylic acid unit (A4) include dicarboxylic acid units (A4-1) to (A4-3), but the dicarboxylic acid unit (A4) is not limited thereto.

[0089] [ka]

[0090] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the above specific examples (A1-1), (A1-7), (A3-2) and (A4-3), and more preferably contains at least one selected from the group consisting of (A3-2) and (A4-3).

[0091] When the polyester resin (1) has dicarboxylic acid units (A), the total mass proportion of the dicarboxylic acid units (A) in the polyester resin (1) is preferably 15% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 55% by mass or less, and even more preferably 25% by mass or more and 50% by mass or less.

[0092] The polyester resin (1) may contain dicarboxylic acid units other than the biphenyl-containing structural unit represented by formula (1) and the dicarboxylic acid unit (A). Examples of the other dicarboxylic acid units include aliphatic dicarboxylic acid units (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The polyester resin (1) may contain one or more types of these dicarboxylic acid units.

[0093] The polyester resin (1) may have at least one diol unit (B) 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), and a diol unit (B8) represented by the formula (B8).

[0094] When the polyester resin (1) has the diol unit (B), the diol unit (B) may be one type or two or more types. The diol unit (B) is preferably at least one selected from the group consisting of a diol unit (B1), a diol unit (B2), a diol unit (B4), a diol unit (B5), and a diol unit (B6), more preferably at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6); More preferably, it is at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), and the diol unit (B6), At least one selected from the group consisting of the diol unit (B1) and the diol unit (B2) is most preferred.

[0095] [ka]

[0096] In formula (B1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0097] Rb 101 The number of carbon atoms in the branched alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 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.

[0098] [ka]

[0099] In formula (B2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0100] Rb 102 The carbon number of the linear alkyl group having 4 to 20 carbon atoms in the formula (Rb) is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples of the alkyl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0101] [ka]

[0102] In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0103] Rb 113 and Rb 213The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 213 The alkyl group in the alkoxy group having from 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 4 carbon atoms is preferably from 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0104] [ka]

[0105] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0106] Rb 104 The alkyl group having 1 to 3 carbon atoms in the formula (Rb) may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably has 1 carbon atom. 104 Specific examples of the group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0107] [ka]

[0108] In formula (B5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0109] Ar 105 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms according to the above formula may be either monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of 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 anthracenylmethyl group, and a phenyl-cyclopentylmethyl group.

[0110] [ka]

[0111] In formula (B6), Rb 116 and Rb 216are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb 406 , Rb 506 , Rb 806 and Rb 906 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0112] 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 from 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 4 carbon atoms is preferably from 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0113] [ka]

[0114] In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0115] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific and preferred embodiments of Rb are the same as those of Rb, 201 , Rb 202 , Rb 204 and Rb 205 "Rb 200 " is collectively referred to as ".

[0116] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably 1 carbon atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0117] 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 and Rb of formula (B8) 408 Since the specific and preferred embodiments of Rb are the same as those of Rb, 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 and Rb 408 "Rb 400 " is collectively referred to as ".

[0118] Rb 400 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0119] Rb 400 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0120] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0121] 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 and Rb of formula (B8) 508 Since the specific and preferred embodiments of Rb are the same as those of Rb, 501 , Rb 502 , Rb 503 , Rb 504 , Rb505 , Rb 506 and Rb 508 "Rb 500 " is collectively referred to as ".

[0122] 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.

[0123] Rb 500 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0124] Rb 500Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0125] 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 and Rb of formula (B8) 808 Since the specific and preferred embodiments of Rb are the same as those of Rb, 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 and Rb 808 "Rb 800 " is collectively referred to as ".

[0126] 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.

[0127] Rb 800 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0128] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0129] 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 and Rb of formula (B8) 908 Since the specific and preferred embodiments of Rb are the same as those of Rb, 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 and Rb 908 "Rb 900 " is collectively referred to as ".

[0130] 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.

[0131] Rb 900 The alkyl group in the alkoxy group having from 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having from 1 to 6 carbon atoms is preferably from 1 to 4, more preferably from 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0132] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0133] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0134] [ka]

[0135] Specific examples of the diol unit (B2) include diol units (B2-1) to (B2-11), but the diol unit (B2) is not limited thereto.

[0136] [ka]

[0137] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0138] [ka]

[0139] Specific examples of the diol unit (B4) include diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0140] [ka]

[0141] Specific examples of the diol unit (B5) include diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0142] [ka]

[0143] Specific examples of the diol unit (B6) include diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0144] [ka]

[0145] Specific examples of the diol unit (B8) include diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0146] [ka]

[0147] When the polyester resin (1) has the diol unit (B), the mass proportion of the diol unit (B) in the polyester resin (1) is preferably 25 mass% or more and 80 mass% or less, more preferably 30 mass% or more and 75 mass% or less, and even more preferably 35 mass% or more and 70 mass% or less.

[0148] The polyester resin (1) may contain other diol units in addition to the biphenyl-containing structural unit represented by formula (1) and the diol unit (B). Examples of other diol units 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.

[0149] The ends of the polyester resin (1) may be capped or modified with a terminal capping agent or a molecular weight modifier used during production. Examples of the terminal capping agent or molecular weight modifier include monohydric phenols, monohydric acid chlorides, monohydric alcohols, and monocarboxylic acids. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m Examples include o-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 thereof. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monocarboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0150] The weight average molecular weight of the polyester resin (1) is preferably 30,000 or more and 300,000 or less, more preferably 40,000 or more and 250,000 or less, and even more preferably 50,000 or more and 200,000 or less. The molecular weight of the polyester resin (1) is a polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography), which uses tetrahydrofuran as an eluent.

[0151] Polyester resin (1) can be obtained by conventional polycondensation of a monomer that provides a biphenyl-containing structural unit represented by formula (1), optionally a monomer that provides a dicarboxylic acid unit (A), optionally a monomer that provides a diol unit (B), and optionally other monomers. Examples of methods for polycondensation of monomers include interfacial polymerization, solution polymerization, and melt polymerization. Interfacial polymerization is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in a water-immiscible organic solvent with a dihydric alcohol dissolved in an aqueous alkaline solution. Examples of literature related to interfacial polymerization include WMA Reckson, J. Poly. Sci., XL399, 1959, and Japanese Patent Publication No. 1965-1959. Because interfacial polymerization has a faster reaction rate than solution polymerization, it can suppress hydrolysis of the dicarboxylic acid halide, resulting in a high molecular weight polyester resin.

[0152] [Polycarbonate resin (1)] In the present disclosure, a polycarbonate resin having a structural unit containing biphenyl represented by formula (1) is referred to as polycarbonate resin (1).

[0153] [ka]

[0154] In formula (1), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group.

[0155] j is an integer of 0 or more and 4 or less, preferably an integer of 0 or more and 3 or less, more preferably an integer of 0 or more and 2 or less, further preferably 0 or 1, and particularly preferably 0. When j is an integer equal to or greater than 1, j R 11 are each independently a methyl group or an ethyl group, and are preferably a methyl group.

[0156] k is an integer of 0 or more and 4 or less, preferably an integer of 0 or more and 3 or less, more preferably an integer of 0 or more and 2 or less, even more preferably 0 or 1, and particularly preferably 0. When k is an integer equal to or greater than 1, k R 12 are each independently a methyl group or an ethyl group, and are preferably a methyl group.

[0157] The polycarbonate resin (1) preferably has a structural unit (1-C) represented by the following formula (1-C) from the viewpoint of having a structural unit containing biphenyl represented by formula (1) in the molecule.

[0158] [ka]

[0159] In formula (1-C), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group, and L C is a single bond or a divalent linking group, and Ar C is an aromatic ring which may have a substituent, and n C is 0, 1 or 2.

[0160] j, k, and R in formula (1-C) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R12 The specific and preferred embodiments are also the same.

[0161] L C When Rc is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Rc 1 )(Rc 2 )-, where Rc 1 and Rc 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rc 1 and Rc 2 may be bonded to form a cyclic alkyl group.

[0162] Rc 1 and Rc 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0163] Rc 1 and Rc 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0164] Rc 1 and Rc 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rc 1 and Rc 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0165] Ar CThe aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring and a naphthalene ring being preferred. Ar C The hydrogen atoms on the aromatic ring of Ar may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. C 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.

[0166] The structural unit (1-C) represented by formula (1-C) is preferably a structural unit (11-C) represented by the following formula (11-C).

[0167] [ka]

[0168] In formula (11-C), j is an integer of 0 to 4, and j R 11 are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R 12 are each independently a methyl group or an ethyl group.

[0169] j, k, and R in formula (11-C) 11 and R 12 are j, k, and R in equation (1), respectively. 11 and R 12 The specific and preferred embodiments are also the same.

[0170] Specific examples of the structural unit (1-C) include the following structural units (1-C1) to (1-C10), but the structural unit (1-C) is not limited thereto.

[0171] [ka]

[0172] The structural unit (1-C) is preferably at least one selected from the group consisting of structural units (1-C3) to (1-C7), more preferably at least one selected from the group consisting of structural units (1-C3) to (1-C6), and even more preferably structural unit (1-C3).

[0173] The polycarbonate resin (1) may have a structural unit other than the biphenyl-containing structural unit represented by formula (1). The structural unit other than the biphenyl-containing structural unit represented by formula (1) will be described below.

[0174] The polycarbonate resin (1) may have at least one structural unit (C) selected from the group consisting of a structural unit (Ca1) represented by the following formula (Ca1), a structural unit (Ca3) represented by the formula (Ca3), a structural unit (Ca4) represented by the formula (Ca4), a structural unit (Cb1) represented by the formula (Cb1), a structural unit (Cb2) represented by the formula (Cb2), a structural unit (Cb3) represented by the formula (Cb3), a structural unit (Cb4) represented by the formula (Cb4), a structural unit (Cb5) represented by the formula (Cb5), a structural unit (Cb6) represented by the formula (Cb6), and a structural unit (Cb8) represented by the formula (Cb8).

[0175] When the polycarbonate resin (1) has the structural unit (C), the structural unit (C) may be one type or two or more types. The structural unit (C) is preferably at least one selected from the group consisting of the structural unit (Cb1), the structural unit (Cb2), the structural unit (Cb3), the structural unit (Cb4), the structural unit (Cb5), the structural unit (Cb6), and the structural unit (Cb8).

[0176] [ka]

[0177] In formula (Ca1), n 101 is an integer between 0 and 4, and n 101 Ra 101are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca1) 101 and n 101 are the Ra in formula (A1), respectively. 101 and n 101 It has the same meaning and specific form as above.

[0178] [ka]

[0179] In formula (Ca3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca3) 301 , Ra 302 , n 301 and n 302 are the Ra in equation (A3), respectively. 301 , Ra 302 , n 301 and n 302 It has the same meaning and specific form as above.

[0180] [ka]

[0181] In formula (Ca4), n 401 is an integer between 0 and 6, and n 401 Ra 401 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. Ra in formula (Ca4) 401 and n401 are the Ra in formula (A4), respectively. 401 and n 401 It has the same meaning and specific form as above.

[0182] [ka]

[0183] In formula (Cb1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb1) 101 , Rb 201 , Rb 401 , Rb 501 , Rb 801 and Rb 901 are Rb in formula (B1), respectively. 101 , Rb 201 , Rb 401 , Rb 501 , Rb 801 and Rb 901 It has the same meaning and specific form as above.

[0184] [ka]

[0185] In formula (Cb2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb2) 102 , Rb 202 , Rb 402 , Rb 502 , Rb 802 and Rb 902 are Rb in formula (B2), respectively. 102 , Rb 202 , Rb 402 , Rb 502 , Rb 802 and Rb 902 It has the same meaning and specific form as above.

[0186] [ka]

[0187] In formula (Cb3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb3) 113 , Rb 213 , d, Rb 403 , Rb 503 , Rb 803 and Rb 903 are Rb in formula (B3), respectively. 113 , Rb 213 , d, Rb 403 , Rb 503 , Rb 803 and Rb 903 It has the same meaning and specific form as above.

[0188] [ka]

[0189] In formula (Cb4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb4) 104 , Rb 204 , Rb 404 , Rb 504 , Rb 804 and Rb 904 are Rb in formula (B4), respectively. 104 , Rb 204 , Rb 404 , Rb 504 , Rb 804 and Rb 904 It has the same meaning and specific form as above.

[0190] [ka]

[0191] In formula (Cb5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Ar in formula (Cb5) 105 , Rb 205 , Rb 405 , Rb 505 , Rb 805 and Rb 905respectively represent Ar in formula (B5) 105 , Rb 205 , Rb 405 , Rb 505 , Rb 805 and Rb 905 It has the same meaning and specific form as above.

[0192] [ka]

[0193] In formula (Cb6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb 406 , Rb 506 , Rb 806 and Rb 906 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb6) 116 , Rb 216 , e, Rb 406 , Rb 506 , Rb 806 and Rb 906 are Rb in formula (B6), respectively. 116 , Rb 216 , e, Rb 406 , Rb 506 , Rb 806 and Rb 906 It has the same meaning and specific form as above.

[0194] [ka]

[0195] In formula (Cb8), Rb 408 , Rb 508 , Rb 808 and Rb 908are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Rb in formula (Cb8) 408 , Rb 508 , Rb 808 and Rb 908 are Rb in formula (B8), respectively. 408 , Rb 508 , Rb 808 and Rb 908 It has the same meaning and specific form as above.

[0196] Specific examples of the structural unit (Ca1) include structural units (Ca1-1) to (Ca1-9), but the structural unit (Ca1) is not limited to these.

[0197] [ka]

[0198] Specific examples of the structural unit (Ca3) include structural units (Ca3-1) and (Ca3-2), but the structural unit (Ca3) is not limited to these.

[0199] [ka]

[0200] Specific examples of the structural unit (Ca4) include structural units (Ca4-1) to (Ca4-3), but the structural unit (Ca4) is not limited to these.

[0201] [ka]

[0202] Specific examples of the structural unit (Cb1) include structural units (Cb1-1) to (Cb1-6), but the structural unit (Cb1) is not limited to these.

[0203] [ka]

[0204] Specific examples of the structural unit (Cb2) include structural units (Cb2-1) to (Cb2-11) shown below, but the structural unit (Cb2) is not limited to these.

[0205] [ka]

[0206] Specific examples of the structural unit (Cb3) include structural units (Cb3-1) to (Cb3-4), but the structural unit (Cb3) is not limited to these.

[0207] [ka]

[0208] Specific examples of the structural unit (Cb4) include structural units (Cb4-1) to (Cb4-7), but the structural unit (Cb4) is not limited to these.

[0209] [ka]

[0210] Specific examples of the structural unit (Cb5) include structural units (Cb5-1) to (Cb5-6), but the structural unit (Cb5) is not limited to these.

[0211] [ka]

[0212] Specific examples of the structural unit (Cb6) include structural units (Cb6-1) to (Cb6-4), but the structural unit (Cb6) is not limited to these.

[0213] [ka]

[0214] Specific examples of the structural unit (Cb8) include structural units (Cb8-1) to (Cb8-3), but the structural unit (Cb8) is not limited to these.

[0215] [ka]

[0216] When the polycarbonate resin (1) has the structural unit (C), the mass proportion of the structural unit (C) in the polycarbonate resin (1) is preferably 20 mass% or more and 70 mass% or less, more preferably 30 mass% or more and 60 mass% or less, and even more preferably 40 mass% or more and 50 mass% or less.

[0217] The polycarbonate resin (1) may contain other structural units in addition to the biphenyl-containing structural unit represented by formula (1) and the structural unit (C). Examples of other structural units include structural units derived from an aliphatic diol (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol) and phosgene, and structural units derived from an alicyclic diol (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A) and phosgene. The polycarbonate resin (1) may contain one or more of these structural units.

[0218] The terminals of the polycarbonate resin (1) are preferably capped or modified with a terminal capping agent or a molecular weight modifier used in the production of the resin. The terminal capping agent or molecular weight modifier is preferably the terminal capping agent or molecular weight modifier described above for the polyester resin (1).

[0219] The weight average molecular weight of the polycarbonate resin (1) is preferably 35,000 or more and 300,000 or less, more preferably 40,000 or more and 250,000 or less, and even more preferably 50,000 or more and 200,000 or less. The molecular weight of the polycarbonate resin (1) is a molecular weight measured in terms of polystyrene by GPC (gel permeation chromatography). GPC is measured by a conventional method using, for example, tetrahydrofuran or chloroform as an eluent.

[0220] The polycarbonate resin (1) can be produced by known polymerization methods (interfacial polymerization, solution polymerization, melt polymerization). Specific examples of the polymerization reaction include a polymerization reaction in which a diol is reacted with a carbonate precursor such as phosgene or a carbonate diester. The structural units of the polycarbonate resin (1) can be introduced into the polycarbonate resin by, for example, using a diol that provides the structural unit in the polymerization.

[0221] Each layer of the photoreceptor will be described in detail below.

[0222] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is less than Ωcm.

[0223] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm inclusive in order to suppress interference fringes that occur when irradiated with laser light. When incoherent light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate by suppressing defects caused by surface irregularities.

[0224] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, which involves pressing the conductive substrate against a rotating grinding wheel and continuously grinding the substrate; and anodizing.

[0225] As a method for roughening the surface, there may be mentioned a method in which, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0226] Anodizing is a surface roughening treatment that uses a metallic (e.g., aluminum) conductive substrate as the anode and anodizes it in an electrolyte solution to form an oxide film on the surface of the conductive substrate. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active in its original state, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are sealed by volume expansion caused by hydration in pressurized steam or boiling water (with the addition of a metal salt such as nickel), converting the film into a more stable hydrated oxide.

[0227] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm, inclusive, and within this range, the film tends to exhibit barrier properties against injection and also tends to suppress an increase in residual potential due to repeated use.

[0228] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acidic treatment solution is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, with the total concentration of these acids preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0229] The boehmite treatment is carried out, for example, by immersing the steel sheet in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the steel sheet with heated steam at 90°C to 120°C for 5 to 60 minutes. The coating film preferably has a thickness of 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution with low coating solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0230] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0231] For example, inorganic particles have a powder resistance (volume resistivity) of 1×10 2 Ωcm or more 1×10 11 Examples include inorganic particles with a particle size of Ωcm or less. Among these, inorganic particles having the above resistance value are preferably metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0232] The specific surface area of inorganic particles measured by the BET method is, for example, 10 m 2 / g or more is preferable. The volume average particle size of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

[0233] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

[0234] The inorganic particles may be surface-treated, and two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0235] Examples of the surface treatment agent include a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, a surfactant, etc. In particular, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0236] 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.

[0237] Two or more silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0238] 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.

[0239] The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0240] Here, it is preferable that the undercoat layer contains an electron-accepting compound (acceptor compound) together with the inorganic particles, from the viewpoint of improving the long-term stability of the electrical properties and the carrier blocking property.

[0241] Examples of the electron-accepting compound include electron-transporting substances such as quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds such as 4-hydroxybenzophenone and 2,3,4-trihydroxybenzophenone. In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure, such as a hydroxyanthraquinone compound, an aminoanthraquinone compound, or an aminohydroxyanthraquinone compound, and specifically, for example, anthraquinone, alizarin, quinizarin, anthrarphine, or purpurin.

[0242] 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.

[0243] The electron-accepting compound can be attached to the surface of the inorganic particles by, for example, a dry method or a wet method.

[0244] The dry method is a method in which, while stirring inorganic particles using a mixer or the like with high shear force, an electron-accepting compound is added dropwise, either directly or dissolved in an organic solvent, or sprayed together with dry air or nitrogen gas to adhere the electron-accepting compound to the surface of the inorganic particles. The electron-accepting compound is preferably added dropwise or sprayed at a temperature below the boiling point of the solvent. After the electron-accepting compound has been added dropwise or sprayed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as they achieve electrophotographic properties.

[0245] The wet method involves dispersing inorganic particles in a solvent using, for example, stirring, ultrasonic waves, a sand mill, an attritor, or a ball mill, while adding an electron-accepting compound. The mixture is stirred or dispersed, and then the solvent is removed to adhere the electron-accepting compound to the surfaces of the inorganic particles. The solvent can be removed, for example, by filtration or distillation. After solvent removal, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound. Examples of such methods include a method of removing the moisture by stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0246] The attachment of the electron-accepting compound may be carried out before or after the inorganic particles are surface-treated with a surface-treating agent, or the attachment of the electron-accepting compound and the surface treatment with a surface-treating agent may be carried out simultaneously.

[0247] The content of the electron-accepting compound is, for example, 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less, based on the inorganic particles.

[0248] Examples of binder resins used in the undercoat layer include known polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents. Examples of binder resins used in the undercoat layer include charge transporting resins having charge transporting groups, conductive resins (such as polyaniline), and the like.

[0249] Among these, the binder resin used in the undercoat layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and in particular, a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, and epoxy resins, and polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins with a curing agent is preferred. When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0250] The undercoat layer may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of additives include known materials such as polycyclic condensation and azo electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Silane coupling agents are used for the surface treatment of inorganic particles as described above, and may also be added to the undercoat layer as an additive.

[0251] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0252] Examples of zirconium chelate compounds include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0253] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-normal-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0254] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0255] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0256] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of polishing methods include buffing, sandblasting, wet honing, and grinding.

[0257] The formation of the undercoat layer is not particularly limited, and a known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating liquid for forming an undercoat layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0258] Examples of solvents for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0259] Examples of a method for dispersing inorganic particles when preparing a coating liquid for forming an undercoat layer include known methods such as using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

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

[0261] The average thickness of the undercoat layer is set, for example, preferably at least 15 μm, more preferably in the range of from 20 μm to 50 μm.

[0262] [Middle layer] An intermediate layer may be further provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (such as polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0263] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0264] The formation of the intermediate layer is not particularly limited, and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating liquid for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it if necessary. The 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, air knife coating, and curtain coating.

[0265] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm, and the intermediate layer may also be used as an undercoat layer.

[0266] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable for use with an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0267] Examples of the charge generating material include azo pigments such as bisazo and trisazo; fused-ring aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0268] Among these, in order to be compatible with laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material, specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine.

[0269] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include fused ring aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0270] The above charge-generating materials may also be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm. However, from the viewpoint of resolution, when using a thin photosensitive layer of 20 μm or less, the electric field strength in the photosensitive layer becomes high, and charge injection from the substrate can easily cause a decrease in charging, resulting in image defects known as black spots. This problem becomes more pronounced when using charge-generating materials that are p-type semiconductors, such as trigonal selenium and phthalocyanine pigments, that are prone to generating dark current.

[0271] In contrast, when n-type semiconductors such as fused-ring aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark current is less likely to occur, and image defects known as black spots can be suppressed even in thin films. The n-type is determined by the polarity of the photocurrent that flows using the commonly used time-of-flight method, and materials that more easily pass electrons as carriers than holes are considered n-type.

[0272] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (e.g., polycondensation product of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, etc. Here, "insulating" means a material having a volume resistivity of 1×10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0273] The compounding ratio of the charge generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass.

[0274] The charge generating layer may contain other known additives.

[0275] The formation of the charge generation layer is not particularly limited, and a known formation method can be used. For example, the charge generation layer can be formed by forming a coating film of a coating liquid for forming the charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer can also be formed by vapor deposition of the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a fused ring aromatic pigment or a perylene pigment is used as the charge generation material.

[0276] Examples of solvents for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0277] Methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming the charge generating layer include, for example, media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by passing through a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0278] Examples of methods for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0279] The thickness of the charge generating layer is set, for example, preferably in the range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0280] [Charge transport layer] The charge transport layer is a layer containing at least a charge transport material and a binder resin. The charge transport material may be a polymer charge transport material.

[0281] Examples of charge transport materials include electron transport compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of charge transport materials also include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0282] Examples of polymer charge transport materials include known chemical substances having charge transport properties, such as poly-N-vinylcarbazole and polysilane. For example, polyester-based polymer charge transport materials are preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0283] Examples of the charge transport material or polymeric charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, paragraphs 0078 to 0080 of Japanese Patent Application Laid-Open No. 2021-117377, paragraphs 0046 to 0048 of Japanese Patent Application Laid-Open No. 2019-035900, paragraphs 0052 to 0053 of Japanese Patent Application Laid-Open No. 2019-012141, paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-071565, and paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-015223 Examples of the compounds include those described in paragraphs 0101 to 0110 of JP 2013-097300 A, paragraph 0116, paragraphs 0309 to 0316 of WO 2019 / 070003 A, paragraphs 0103 to 0107 of JP 2018-159087 A, and paragraphs 0102 to 0113 of JP 2021-148818 A.

[0284] From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a compound (D1) represented by the following formula (D1), a compound (D2) represented by the following formula (D2), a compound (D3) represented by the following formula (D3), and a compound (D4) represented by the following formula (D4).

[0285] [ka]

[0286] In formula (D1), 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 ) is R T4 , R T5 , R T6 , R T7 and R T8 R is independently a hydrogen atom, an alkyl group, or an aryl group. T5 and R T6 When is an aryl group, the aryl groups are connected to each other by -C(R 51 )(R 52 )- and / or -C(R 61 )=C(R 62 R 51 , R 52 , R 61 and R 62 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0287] The group in formula (D1) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0288] From the viewpoint of charge mobility, the compound (D1) is preferably an aryl group or —CH—CH═CH—CH═C(R T7 )(R T8 ) is preferred, and a compound (D'1) represented by the following formula (D'1) is more preferred.

[0289] [ka]

[0290] In formula (D'1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132are each independently a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0291] [ka]

[0292] In formula (D2), R T201 , R T202 , R T211 and R T212 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ) R T21 , R T22 , R T23 , R T24 and R T25 R is independently a hydrogen atom, an alkyl group, or an aryl group. T221 and R T222 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. Tm1, Tm2, Tn1, and Tn2 are each independently 0, 1, or 2.

[0293] The group in formula (D2) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0294] From the viewpoint of charge mobility, the compound (D2) is preferably an alkyl group, an aryl group, or a -CH=CH-CH=C(R T24 )(R T25) is preferred, and the compound having at least one alkyl group, aryl group, or -CH=CH-CH=C(R T24 )(R T25 ) is more preferred.

[0295] [ka]

[0296] In formula (D3), R T301 , R T302 , R T311 and R T312 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ) is R T31 , R T32 , R T33 , R T34 and R T35 R is independently a hydrogen atom, an alkyl group, or an aryl group. T321 , R T322 and R T331 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2.

[0297] The group in formula (D3) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0298] [ka]

[0299] In formula (D4), R T401 , R T402 , R T411 and R T412 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ) R T41 , R T42 , R T43 , R T44 and R T45 R is independently a hydrogen atom, an alkyl group, or an aryl group. T421 , R T422 and R T431 are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 are each independently 0, 1, or 2.

[0300] The group in formula (D4) may be substituted with a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0301] The mass ratio of the charge transport material in the charge transport layer is preferably from 20 to 70% by mass, more preferably from 25 to 60% by mass, and even more preferably from 30 to 50% by mass.

[0302] The charge transport layer contains at least a polyester resin (1) and / or a polycarbonate resin (1) as a binder resin. When the charge transport layer contains 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 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. When the polyester resin (1) is used in combination with another resin, the other resin to be used in combination is preferably a polycarbonate resin (1).

[0303] When the charge transport layer contains a polyester resin (1) and a polycarbonate resin (1) as binder resins, the mass ratio of the two resins, polyester resin (1):polycarbonate resin (1), is preferably 95:5 to 50:50, more preferably 90:10 to 55:45, and even more preferably 85:15 to 60:40.

[0304] The charge transport layer may contain a binder resin other than the polyester resin (1) and the polycarbonate resin (1). Examples of the other binder resin include polyester resins other than the polyester resin (1), polycarbonate resins other than the polycarbonate resin (1), methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, and polysilanes. These binder resins may be used alone or in combination of two or more.

[0305] The charge transport layer may contain other known additives, such as antioxidants, leveling agents, antifoaming agents, fillers, and viscosity modifiers.

[0306] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it if necessary.

[0307] Examples of solvents for preparing the coating solution for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination.

[0308] Examples of a coating method for applying the coating liquid for forming the charge transport layer onto the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0309] The average thickness of the charge transport layer is preferably from 20 μm to 50 μm, more preferably from 25 μm to 45 μm, and even more preferably from 30 μm to 40 μm.

[0310] [Single-layer photosensitive layer] The single-layer photosensitive layer (charge generation / charge transport layer) is a layer containing a charge generation material, a charge transport material, a binder resin, and, if necessary, other additives. These materials are the same as those described for the charge generation layer and the charge transport layer.

[0311] The single-layer photosensitive layer contains at least a polyester resin (1) and / or a polycarbonate resin (1) as a binder resin. When the single-layer photosensitive layer contains a polyester resin (1) as a binder resin, the proportion of the polyester resin (1) in the total amount of binder resins 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. When the polyester resin (1) is used in combination with another resin, the other resin to be used in combination is preferably a polycarbonate resin (1).

[0312] When the single-layer photosensitive layer contains polyester resin (1) and polycarbonate resin (1) as binder resins, the mass ratio of the two resins, polyester resin (1):polycarbonate resin (1), is preferably 95:5 to 40:60.

[0313] The mass ratio of the charge generating material in the single-layer photosensitive layer is preferably from 0.1% to 10% by mass, and more preferably from 0.8% to 5% by mass.

[0314] The mass proportion of the charge transport material in the single-layer photosensitive layer is preferably 30% by mass to 70% by mass, more preferably 35% by mass to 65% by mass, and even more preferably 40% by mass to 60% by mass.

[0315] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer.

[0316] The average thickness of the single-layer photosensitive layer is preferably from 25 μm to 50 μm, more preferably from 28 μm to 45 μm, and even more preferably from 30 μm to 40 μm.

[0317] [Protective layer] A protective layer may be provided on the photosensitive layer as needed, for example, to prevent chemical changes in the photosensitive layer when charged, or to further improve the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a layer made of a cured film (crosslinked film) as the protective layer. Examples of such a layer include the following layers 1) and 2).

[0318] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer containing a polymer or crosslinked product of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material that does not have a charge transport skeleton and has a reactive group (i.e., a layer containing a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material).

[0319] The reactive group of the reactive group-containing charge transport material may be a chain polymerizable group, an epoxy group, -OH, -OR (wherein R represents an alkyl group), -NH2, -SH, -COOH, or -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R Q2 represents a hydrogen atom, an alkyl group or a trialkylsilyl group, and Qn represents an integer of 1 to 3.

[0320] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specific examples include groups containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among these, a group containing at least one selected from a vinyl group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof is preferred as the chain polymerizable group because of its excellent reactivity.

[0321] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it has a known structure in electrophotographic photoreceptors, and examples thereof include a skeleton derived from a nitrogen-containing hole transport compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and having a conjugated structure with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0322] 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.

[0323] The protective layer may also contain other known additives.

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

[0325] Examples of solvents for preparing the coating liquid for forming the protective layer include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as tetrahydrofuran and dioxane, cellosolve solvents such as ethylene glycol monomethyl ether, and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination. The coating liquid for forming the protective layer may be a solvent-free coating liquid.

[0326] 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, air knife coating, and curtain coating.

[0327] The thickness of the protective layer is set, for example, preferably in the range of 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less.

[0328] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photosensitive member, a charging device that charges the surface of the electrophotographic photosensitive member, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member, a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and a transfer device that transfers the toner image to the surface of a recording medium. The electrophotographic photosensitive member according to the present embodiment is used as the electrophotographic photosensitive member.

[0329] 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 after transfer of a toner image but before charging; an apparatus including a static elimination device that irradiates the surface of an electrophotographic photosensitive member with static elimination light to eliminate static electricity after transfer of a toner image but before charging; and an apparatus including an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0330] 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 that performs primary transfer of the toner image formed on the surface of the electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer device that performs secondarily transfer of the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0331] The image forming apparatus according to this embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0332] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include, for example, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0333] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. The main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0334] FIG. 3 is a schematic diagram showing an example of the configuration of an image forming apparatus according to this embodiment. As shown in FIG. 3 , the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photosensitive member 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the electrophotographic photosensitive member 7 through the opening of the process cartridge 300, and the transfer device 40 is disposed at a position facing the electrophotographic photosensitive member 7 via the intermediate transfer member 50, with a portion of the intermediate transfer member 50 being in contact with the electrophotographic photosensitive member 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred onto the intermediate transfer member 50 onto a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to examples of transfer devices.

[0335] 3 integrally supports an electrophotographic photosensitive member 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) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photosensitive member 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0336] FIG. 3 shows an example of an image forming apparatus that includes a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists cleaning, which may be arranged as needed.

[0337] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0338] -Charging device- The charging device 8 may be, for example, a contact-type charger using a conductive or semi-conductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also usable are non-contact type roller chargers, scorotron chargers and corotron chargers that utilize corona discharge, and other known chargers.

[0339] -Exposure equipment- The exposure device 9 may be, for example, an optical system that exposes the surface of the electrophotographic photosensitive member 7 to light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photosensitive member. The wavelength of semiconductor lasers is mainly near-infrared, with an oscillation wavelength around 780 nm. However, this wavelength is not limited to this, and lasers with an oscillation wavelength in the 600 nm range or blue lasers with an oscillation wavelength of 400 nm to 450 nm may also be used. Furthermore, for color image formation, a surface-emitting laser light source capable of outputting multiple beams is also effective.

[0340] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contact or non-contact application of a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected depending on the purpose. For example, it may be a known developing device that has a function of applying a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, roller, or the like. Among these, a developing roller that holds a developer on its surface is preferred.

[0341] The developer used in the developing device 11 may be a one-component developer containing only toner, or a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Known developers are used.

[0342] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning type or a simultaneous development cleaning type may also be used.

[0343] -Transfer device- Examples of the transfer device 40 include a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a known transfer charger such as a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0344] -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.

[0345] FIG. 4 is a schematic diagram showing another example of the configuration of the image forming apparatus according to the present embodiment. The image forming apparatus 120 shown in Fig. 4 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photosensitive member is used per color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem-type apparatus. [Example]

[0346] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples in any way. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, syntheses, treatments, manufacturing, etc. were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0347] <Synthesis of polyester resin> [Synthesis of polyester resin (PE-1-1)] A suspension was prepared by adding 12.64 g of 4,4'-(2-ethylhexylidene)diphenol, 0.123 g of 4-tert-butylphenol, 0.063 g of sodium hydrosulfite, and 250 ml of water to a reaction vessel equipped with a stirrer. While stirring this suspension at 20°C, 4.84 g of sodium hydroxide, 0.200 g of benzyltributylammonium chloride, and 150 ml of water were added and stirred for 30 minutes under a nitrogen atmosphere to prepare an aqueous solution. 200 ml of methylene chloride was added to this aqueous solution and stirred for 30 minutes under a nitrogen atmosphere. Then, 12.0 g of 4,4'-biphenyldicarbonyl chloride was added as a powder. After the addition, the mixture was stirred for 2 hours under a nitrogen atmosphere at 20°C to allow the polymerization reaction to proceed. The resulting solution was then purified as follows: The post-polymerization solution was diluted with 300 ml of methylene chloride, and the aqueous layer was removed. After washing with a dilute acetic acid solution and ion-exchanged water, the solution was poured into methanol to precipitate a polyester resin. The precipitated polyester resin was filtered off and dried at 50°C. The dried polyester resin was redissolved in 900 ml of tetrahydrofuran and poured into methanol to precipitate a polyester resin. The precipitated polyester resin was filtered off, washed with methanol, and dried at 50°C to obtain 17.4 g of a white polyester resin. The weight-average molecular weight of this polyester resin was 110,000.

[0348] [Synthesis of polyester resin (PE-1-2)] A solution was prepared by placing 13.1 g of 4,4'-(2-ethylhexylidene)diphenol and 8.26 g of triethylamine in a reaction vessel equipped with a stirrer, and adding 60 ml of methylene chloride. While stirring this solution at a temperature of 5°C, 11.33 g of 4,4'-biphenyldicarbonyl chloride was added as a powder. After the addition was complete, the solution temperature was raised to 30°C, and the solution was stirred for 2 hours under a nitrogen atmosphere to allow the polymerization reaction to proceed. The solution after polymerization was subjected to the following purification treatment. The mixture was left to stand to separate into an aqueous layer and an organic layer, and the aqueous layer was removed. The organic layer was washed with ion-exchanged water until the pH was neutral. The pressure inside the reaction vessel was reduced and the methylene chloride was distilled off, yielding 18.0 g of polyester resin. The weight-average molecular weight of this polyester resin was 110,000.

[0349] [Synthesis of polyester resin (PE-xy)] The polyester resins (PE-xy) shown in Table 1 were synthesized in the same manner as in the synthesis of polyester resins (PE-1-1) or (PE-1-2), except that the types of monomers used in the polymerization reaction were changed and the amounts charged were altered so that the number of moles of the monomers was the same. Here, x is an integer of 2 to 7, and y is an integer of 1 to 2. The polyester resin (PE-x-1) was obtained by the same polymerization method as that for the polyester resin (PE-1-1). The polyester resin (PE-x-2) was obtained by the same polymerization method as that for the polyester resin (PE-1-2).

[0350] [Synthesis of comparative polyester resin] Polyester resin (PE-X1) shown in Table 1 was synthesized in the same manner as in the synthesis of polyester resin (PE-1-1), except that the type of monomer used in the polymerization reaction was changed. In the same manner as in the synthesis of polyester resin (PE-1-2), However, the type of monomer used in the polymerization reaction was changed, and the amount charged was changed so that the number of moles of the monomers was the same, thereby synthesizing the polyester resin (PE-X2) shown in Table 1.

[0351] [Acid value measurement of polyester resin] The acid value of the polyester resin was determined by the following measurement method. 50 mg of polyester resin was weighed out and dissolved in 20 mL of tetrahydrofuran to prepare the titration sample. Using a GT-310 automatic potentiometric titrator (Nitto Seiko Analytech Co., Ltd.), 0.01 mL of 0.005 mol / L potassium hydroxide-isopropyl alcohol solution was added dropwise to the titration sample to create a titration curve. The inflection point of the titration curve was set as the endpoint, and the titration volume up to the endpoint was calculated. The acid value of the polyester resin (mgKOH / g) was calculated from the titration volume and the mass (50 mg) of the polyester resin used for titration. The results are shown in Table 1.

[0352] 1-A3 and the like shown in Table 1 are specific examples of the dicarboxylic acid unit (1-A) already described. A3-2 and the like shown in Table 1 are specific examples of the dicarboxylic acid unit (A) already described. B1-4 and the like shown in Table 1 are specific examples of the diol unit (B) already described. When there are two types of dicarboxylic acid units, Table 1 also shows the composition ratio (mol %).

[0353] [Table 1]

[0354] <Synthesis of polycarbonate resin> [Synthesis of Polycarbonate Resin for the Present Embodiment] Polycarbonate resins (PC-1) to (PC-4) shown in Table 2 were synthesized by reacting diphenol with phosgene.

[0355] [Synthesis of comparative polycarbonate resin] A polycarbonate resin (PC-X1) shown in Table 2 was synthesized by reacting diphenol with phosgene.

[0356] 1-C3 and the like shown in Table 2 are specific examples of the structural unit (1-C) already described. Cb6-3 and the like shown in Table 2 are specific examples of the aforementioned structural unit (C). When there are two types of constitutional units, Table 2 also shows the composition ratio (mol %).

[0357] [Table 2]

[0358] <Production of a photoreceptor having a laminated photosensitive layer> [Example S1] - Formation of undercoat layer - As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1.6 mm was prepared.

[0359] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 100 parts of a silane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0360] 110 parts of the surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran and stirred, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring for 5 hours at 50° C. Thereafter, the solid content was filtered off under reduced pressure and dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin added thereto.

[0361] A solution of 60 parts alizarin-modified zinc oxide, 13.5 parts curing agent (blocked isocyanate, trade name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts butyral resin (trade name: S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) dissolved in 68 parts methyl ethyl ketone was mixed with 5 parts methyl ethyl ketone and dispersed for 2 hours using 1 mm diameter glass beads in a sand mill to obtain a dispersion. To the dispersion, 0.005 parts dioctyltin dilaurate as a catalyst and 4 parts silicone resin particles (trade name: Tospearl 145, manufactured by Momentive Performance Materials Co., Ltd.) were added to obtain a coating solution for forming an undercoat layer. The coating solution for forming the undercoat layer was applied to the outer surface of a conductive substrate by dip coating and dried and cured at 185°C for 35 minutes to form an undercoat layer. The average thickness of the undercoat layer was 25 μm.

[0362] - Formation of charge generation layer - A mixture consisting of 15 parts of hydroxygallium phthalocyanine (CGL) as a charge-generating material (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using CuKα characteristic X-rays), 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using 1 mm diameter glass beads for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge-generating layer. The coating solution for forming the charge-generating layer was dip-coated onto the undercoat layer and dried at room temperature (25°C±3°C) to form a charge-generating layer with an average thickness of 0.25 μm.

[0363] - Formation of charge transport layer - Binder resin: Polyester resin (PE-1-1) 60 parts ·Charge transport material: CTM-1 ···40 parts The above materials were dissolved or dispersed in a mixed solvent of 550 parts tetrahydrofuran and 50 parts toluene to obtain a coating solution for forming a charge transport layer. The coating solution for forming a charge transport layer was dip-coated onto the charge generation layer and dried at a temperature of 150°C for 40 minutes to form a charge transport layer with an average thickness of 32 μm.

[0364] [ka]

[0365] [Examples S2 to S19, Comparative Examples S1 to S13] Each photoreceptor was prepared in the same manner as in Example S1, except that the type and amount of binder resin in forming the charge transport layer was changed to the specifications shown in Table 3.

[0366] <Production of a photoreceptor having a single-layer type photosensitive layer> [Example T1] - Formation of photosensitive layer - Binder resin: Polyester resin (PE-1-1) 50 parts Charge-generating material: 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 an X-ray diffraction spectrum using CuKα characteristic X-rays) ·Charge transport material: CTM-1 ···40 parts ·Charge transport material: CTM-2 ···9 parts The above materials were dissolved or dispersed in a mixed solvent of 175 parts tetrahydrofuran and 75 parts toluene, and dispersed for 4 hours in a sand mill using 1 mm diameter glass beads to obtain a coating solution for forming a photosensitive layer. The coating solution for forming a photosensitive layer was applied to the outer surface of a conductive substrate (an aluminum cylindrical tube with an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1.6 mm) by dip coating, and dried at a temperature of 150°C for 60 minutes to form a single-layer photosensitive layer with an average thickness of 36 μm.

[0367] [ka]

[0368] [Examples T2 to T8, Comparative Examples T1 to T5] Each photoreceptor was produced in the same manner as in Example T1, except that the type and amount of binder resin were changed to the specifications shown in Table 4.

[0369] <Photoreceptor performance evaluation> [Wear resistance] The photoreceptor was mounted on an electrophotographic image forming apparatus (Apeos C5570, Fujifilm Business Innovation Co., Ltd.). In a low-temperature, low-humidity environment (10°C, 15% relative humidity), 5,000 copies of each 20% halftone image in yellow, magenta, cyan, and black were printed on A3-sized paper, for a total of 20,000 copies. Before and after image formation, the thickness of the charge transport layer or single-layer photosensitive layer was measured at four locations circumferentially spaced 90° apart from the axial center of the photoreceptor. Measurements were performed using an electromagnetic film thickness meter (Fisher Instruments, Permascope). The thicknesses at the four locations were averaged, and the average value after image formation was subtracted from the average value before image formation to calculate the wear amount. The wear amount was divided by the number of photoreceptor running cycles to calculate the wear rate (nm / kcy) and classified as follows. The results are shown in Tables 3 and 4. A: The wear rate (nm / kcy) is 16 or less. B: The wear rate (nm / kcy) is more than 16 and 24 or less. C: The wear rate (nm / kcy) is greater than 24.

[0370] [Filming] The photoreceptor was mounted in an electrophotographic image forming apparatus (Apeos C6570, Fujifilm Business Innovation Co., Ltd.). In a high-temperature, high-humidity environment (28°C, 85% relative humidity), 1,000 sheets of A3-sized plain paper were printed with a black grid chart image at 5% image density. After image formation, the surface of the photoreceptor was visually observed and classified as follows. The results are shown in Tables 3 and 4. A: No filming is observed. B: Slight filming is observed in some areas. No practical problems. C: Filming is observed. Problems in practical use.

[0371] [Table 3]

[0372] [Table 4]

[0373] 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.

[0374] (((1))) a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the conductive substrate; the charge transport layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by formula (1), the acid value of the charge transport layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. (((2))) The electrophotographic photoreceptor according to (((1))), wherein the charge transport material accounts for 30% by mass or more and 50% by mass or less of the charge transport layer. (((3))) the polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by formula (1-A) and a diol unit (1-B) represented by formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by formula (1-C): The electrophotographic photoreceptor according to (((1))) or (((2))). (((4))) A conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), the acid value of the single-layer photosensitive layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. (((5))) The electrophotographic photoreceptor according to (((4))), wherein the mass ratio of the charge transport material in the single-layer photosensitive layer is 40 mass % or more and 60 mass % or less. (((6))) the polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by formula (1-A) and a diol unit (1-B) represented by formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by formula (1-C): The electrophotographic photoreceptor according to (((4))) or (((5))). (((7))) An electrophotographic photoreceptor according to any one of (((1))) to (((6))), A process cartridge that is detachably attached to an image forming apparatus. (((8))) an electrophotographic photoreceptor according to any one of (((1))) to (((6))); a charging device that charges the surface of the electrophotographic photosensitive member; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive member; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image; a transfer device that transfers the toner image onto a surface of a recording medium; An image forming apparatus comprising:

[0375] According to (((1))), (((2))), or (((3))), an electrophotographic photoreceptor is provided which is equipped with a laminated photosensitive layer and has excellent abrasion resistance and is less susceptible to filming compared to an electrophotographic photoreceptor in which the acid value of the charge transport layer is more than 2 mgKOH / g. According to (((4))), (((5))), or (((6))), an electrophotographic photoreceptor is provided which is equipped with a single-layer type photosensitive layer and which is excellent in abrasion resistance and less susceptible to filming compared to an electrophotographic photoreceptor in which the acid value of the single-layer type photosensitive layer is more than 2 mgKOH / g. According to (((7))), a process cartridge is provided that includes an electrophotographic photosensitive member that is superior in abrasion resistance and less susceptible to filming, compared to an electrophotographic photosensitive member in which the charge transport layer of the multilayer photosensitive layer or the single-layer photosensitive layer has an acid value of more than 2 mgKOH / g. According to (((8))), an image forming apparatus is provided that includes an electrophotographic photoreceptor that is superior in abrasion resistance and less susceptible to filming, compared to an electrophotographic photoreceptor in which the charge transport layer of the multilayer photoreceptor or the single-layer photoreceptor has an acid value of more than 2 mgKOH / g. [Explanation of symbols]

[0376] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0377] 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming apparatus, 120 image forming apparatus, 131 cleaning blade, 132 fibrous member (roll-shaped), 133 fibrous member (flat brush-shaped), 300 process cartridge

Claims

1. a conductive substrate; and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the conductive substrate; the charge transport layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), the acid value of the charge transport layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. 【Chemical 1】 In formula (1), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group.

2. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport material accounts for 30% by weight or more and 50% by weight or less of the charge transport layer.

3. The polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by the following formula (1-A) and a diol unit (1-B) represented by the following formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by the following formula (1-C): The electrophotographic photoreceptor according to claim 1 . 【Chemistry 2】 In formula (1-A), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ａ is a single bond or a divalent linking group, and Ar Ａ represents an aromatic ring which may have a substituent, and n Ａ is 0, 1 or 2. In formula (1-B), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ｂ is a single bond or a divalent linking group, and Ar Ｂ represents an aromatic ring which may have a substituent, and n Ｂ is 0, 1 or 2. In formula (1-C), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ｃ is a single bond or a divalent linking group, and Ar Ｃ represents an aromatic ring which may have a substituent, and n Ｃ is 0, 1 or 2.

4. A conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer contains a charge transport material and at least one of a polyester resin and a polycarbonate resin having a structural unit containing biphenyl represented by the following formula (1), the acid value of the single-layer photosensitive layer is 2 mgKOH / g or less; Electrophotographic photoreceptor. 【Chemistry 3】 In formula (1), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group.

5. 5. The electrophotographic photoreceptor according to claim 4, wherein the mass ratio of the charge transport material in the single-layer photosensitive layer is 40 mass % or more and 60 mass % or less.

6. The polyester resin has at least one of a dicarboxylic acid unit (1-A) represented by the following formula (1-A) and a diol unit (1-B) represented by the following formula (1-B), The polycarbonate resin has a structural unit (1-C) represented by the following formula (1-C): The electrophotographic photoreceptor according to claim 4. 【Chemistry 4】 In formula (1-A), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ａ is a single bond or a divalent linking group, and Ar Ａ represents an aromatic ring which may have a substituent, and n Ａ is 0, 1 or 2. In formula (1-B), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ｂ is a single bond or a divalent linking group, and Ar Ｂ represents an aromatic ring which may have a substituent, and n Ｂ is 0, 1 or 2. In formula (1-C), j is an integer of 0 to 4, and j R １１ are each independently a methyl group or an ethyl group, k is an integer of 0 to 4, and k R １２ are each independently a methyl group or an ethyl group, and L Ｃ is a single bond or a divalent linking group, and Ar Ｃ represents an aromatic ring which may have a substituent, and n Ｃ is 0, 1 or 2.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6 is provided, A process cartridge that is detachably attached to an image forming apparatus.

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

Images