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 burn-in ghost on an image.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate, and a lamination type photosensitive layer having a charge generating layer and a charge transport layer. The charge transport layer contains polyester resin having a constitutional unit including biphenyl represented by the formula (1). The amount of aromatic carboxylic halide in the charge transport layer is 15×10-8 mol / g or less per unit mass of the charge transport layer.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Patent Document 1 discloses a polyarylate resin obtained by an interfacial polycondensation reaction between an aromatic dicarboxylic acid component and an aromatic dihydric alcohol component, the polyarylate resin having 10 ppm or less of carboxylic acid halide terminals, and an electrophotographic photoreceptor containing the polyarylate resin in a photosensitive layer. Patent Document 2 discloses an electrophotographic photoreceptor having a photosensitive layer containing a charge generating material, two kinds of charge transporting materials represented by a predetermined structural formula, and at least one selected from the group consisting of a hindered phenol-based antioxidant having a molecular weight of 300 or more and a benzophenone-based ultraviolet absorber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-169617 A [Patent Document 2] JP 2016-143024 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure relates to an electrophotographic photoreceptor having a laminated photosensitive layer, and the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 The object of the present invention is to provide an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghosting, as compared with a case in which the content exceeds 100 moles / g. The present disclosure relates to an electrophotographic photoreceptor having a single-layer type photosensitive layer, and the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8The object of the present invention is to provide an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghosting, as compared with a case in which the content exceeds 100 moles / g. [Means for solving the problem]

[0005] 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.

[0006] <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 polyester resin having a structural unit containing biphenyl represented by formula (1), The amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 moles / g or less, Electrophotographic photoreceptor. <2> The amount of aromatic carboxylic acid halide in the charge transport layer is 8×10 per unit mass of the charge transport layer. ―8 moles / g or less, <1> The electrophotographic photoreceptor according to claim 1. <3> The aromatic carboxylic acid halide is a compound represented by formula (2). <1> or <2> The electrophotographic photoreceptor according to claim 1. <4> The aromatic carboxylic acid halide comprises an aromatic carboxylic acid chloride. <1> ~ <3> 13. The electrophotographic photoreceptor according to claim 12, <5> the charge transport layer further contains a polycarbonate resin; <1> ~ <4> 13. The electrophotographic photoreceptor according to claim 12, <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). <1> ~ <5> 13. The electrophotographic photoreceptor according to claim 12, <7> The polyester resin has at least one dicarboxylic acid unit selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). <1> ~ <6> 13. The electrophotographic photoreceptor according to claim 12, <8> the polyester resin has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), and a diol unit (B8) represented by formula (B8); <1> ~ <7> 13. The electrophotographic photoreceptor according to claim 12, <9> A conductive substrate and a single-layer type photosensitive layer disposed on the conductive substrate, the single-layer type photosensitive layer contains a polyester resin having a structural unit containing biphenyl represented by formula (1), The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 moles / g or less, Electrophotographic photoreceptor. <10> The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 6×10 ―8 moles / g or less, <9> The electrophotographic photoreceptor according to claim 1. <11> The aromatic carboxylic acid halide is a compound represented by formula (2). <9> or <10> The electrophotographic photoreceptor according to claim 1. <12> The aromatic carboxylic acid halide comprises an aromatic carboxylic acid chloride. <9> ~ <11> 13. The electrophotographic photoreceptor according to claim 12, <13> The single-layer photosensitive layer further contains a polycarbonate resin. <9> ~ <12> 13. The electrophotographic photoreceptor according to claim 12, <14> 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). <9> ~ <13> 13. The electrophotographic photoreceptor according to claim 12, <15> The polyester resin has at least one dicarboxylic acid unit selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). <9> ~ <14> 13. The electrophotographic photoreceptor according to claim 12, <16> the polyester resin has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), and a diol unit (B8) represented by formula (B8); <9> ~ <15> 13. The electrophotographic photoreceptor according to claim 12, <17> <1> ~ <16> 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. <18> <1> ~ <16> and an electrophotographic photoreceptor according to any one of the above items. a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: Effect of the Invention

[0007] <1> , <3> , <4> , <5> , <6> , <7> or <8> According to the present invention, in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. <2> According to the present invention, in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 8×10 per unit mass of the charge transport layer. ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. <9> , <11> , <12> , <13> , <14> , <15> or <16> According to the invention, in an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. <10> According to the invention, in an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 6×10 ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. <17> According to the present invention, in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 or in the case of an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 As compared with the case where the content exceeds mol / g, a process cartridge is provided which has excellent abrasion resistance of an electrophotographic photosensitive member and is less susceptible to ghost marks on images. <18> According to the present invention, in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 or in the case of an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 As compared with the case where the content exceeds mol / g, an image forming apparatus is provided in which the abrasion resistance of the electrophotographic photoreceptor is excellent and image burn-in ghosts are less likely to occur in the image. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photoreceptor according to the first embodiment. [Diagram 2] FIG. 11 is a partial cross-sectional view showing an example of a layer structure of an electrophotographic photoreceptor according to a second embodiment. [Diagram 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic configuration diagram illustrating another example of an image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiments, and are not intended to limit the scope of the embodiments.

[0010] In the present disclosure, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0011] 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.

[0012] When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0013] In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0014] In the present disclosure, unless otherwise specified, the alkyl group and the alkylene group include any of straight-chain, branched, and cyclic groups.

[0015] In the present disclosure, a hydrogen atom in an organic group, an aromatic ring, a linking group, an alkyl group, an alkylene group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, and the like may be substituted with a halogen atom.

[0016] In the present disclosure, when a compound is shown by a structural formula, the symbols (C and H) representing carbon atoms and hydrogen atoms in the hydrocarbon group and / or hydrocarbon chain may be omitted.

[0017] In the present disclosure, the term "structural unit" of a copolymer or resin is synonymous with a monomer unit.

[0018] <Electrophotographic photoreceptor> The present disclosure provides a first embodiment and a second embodiment as an electrophotographic photoreceptor (hereinafter also referred to as a "photoreceptor").

[0019] The photoreceptor according to the first embodiment includes a conductive substrate and a laminated photoreceptor layer having a charge generating layer and a charge transport layer disposed on the conductive substrate. The photoreceptor according to the first embodiment may further include other layers (e.g., an undercoat layer, an intermediate layer).

[0020] 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).

[0021] Fig. 1 is a partial cross-sectional view showing an example of the layer structure of the photoreceptor according to the first embodiment. The photoreceptor 10A shown in Fig. 1 has a laminated photosensitive layer. The photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called function-separated photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3. The undercoat layer 2 may or may not be present.

[0022] Fig. 2 is a partial cross-sectional view that shows an example of the layer structure of a photoreceptor according to a second embodiment. The photoreceptor 10B shown in Fig. 2 has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are laminated in this order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5. The undercoat layer 2 may or may not be present.

[0023] In the photoreceptor according to the first embodiment, the charge transport layer contains a polyester resin having a structural unit containing biphenyl represented by formula (1), and the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 moles / g or less.

[0024] The photoreceptor according to the second embodiment has a single-layer photosensitive layer containing a polyester resin having a structural unit containing biphenyl represented by formula (1), and the amount of aromatic carboxylic acid halide in the single-layer photosensitive layer is 15×10 per unit mass of the single-layer photosensitive layer. ―8 moles / g or less.

[0025] [ka]

[0026] 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.

[0027] The biphenyl represented by formula (1) may be the entire structure or a part thereof obtained by removing an ester bond (-C(=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 be directly bonded to an ester bond or may be bonded to an ester bond via another atom or atomic group, independently of each other.

[0028] Hereinafter, when matters common to the first and second embodiments are described, both forms will be collectively referred to as this embodiment.

[0029] The photoreceptor according to this embodiment has excellent abrasion resistance and is less susceptible to image burn-in ghosting. The mechanism behind this is believed to be as follows. The term "burn-in ghost" refers to an image defect in which the surface potential of the photosensitive layer decreases in areas with a high exposure history, causing the density of a halftone image to increase.

[0030] A photosensitive layer containing a polyester resin having a structural unit containing biphenyl represented by formula (1) as a binder resin has strong cohesive force between the polyester resins due to stacking of the biphenyls represented by formula (1), thereby improving the abrasion resistance of the photosensitive layer. However, when using a photoconductor equipped with the above-mentioned photosensitive layer, burn-in ghosts may occur in the image. This is presumably due to aromatic carboxylic acid halides that are generated during the synthesis of the polyester resin. Although the detailed mechanism is not entirely clear, photosensitive layers that contain aromatic carboxylic acid halides tend to have a lower surface potential when images are formed continuously, which makes them prone to a phenomenon known as burn-in ghosts.

[0031] In the photoreceptor according to the first embodiment, the amount of aromatic carboxylic acid halide in the charge transport layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 8×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0032] In the photoreceptor according to the second embodiment, the amount of aromatic carboxylic acid halide in the single-layer photosensitive layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 6×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0033] In this embodiment, the amount (mol) of the aromatic carboxylic acid halide contained in the charge transport layer or the single-layer photosensitive layer is determined by preparing a measurement sample according to the following procedures (1) to (6) and quantifying the amount by HPLC (High Performance Liquid Chromatography). The following description is for the first embodiment. The second embodiment is similar to the first embodiment, except that the "charge transport layer" is replaced with a "single-layer type photosensitive layer."

[0034] (1) Dissolve 2 g of diethylamine in methylene chloride to prepare 100 g of solution (1). (2) The charge transport layer is peeled off from the photoreceptor, and 1 g is precisely weighed out. (3) 1 g of the charge transport layer is dissolved in the solution (1) and stirred overnight to react the aromatic carboxylic acid halide with diethylamine. (4) After the reaction, methylene chloride is removed from the solution by distillation under reduced pressure. (5) The residue is dissolved in 1 ml of N-methyl-2-pyrrolidone (a good solvent for polyester resins), and 9 ml of methanol (a poor solvent for polyester resins) is added to precipitate the polyester resin. (6) Filter the supernatant through a PTFE filter, and use the filtrate as the HPLC measurement sample. HPLC is performed using an ODS column as the HPLC separation column, water containing phosphoric acid and acetonitrile as the eluent, and a photodiode array detector (example of detection wavelength: 254 nm) as the detection device. A calibration curve for quantification is created using 4,4'-biphenyldicarbonyl chloride and 4-(4-phenylcarbonyl chloride)benzoic acid as standard substances, and standard samples (prepared with six samples in the concentration range of 1 ppm to 100 ppm) in which the compounds are dissolved in solution (1). It is assumed that all carbonyl chloride terminals react with diethylamine, and a diamide compound (molecular weight 352.5) ​​or a monoamide compound (molecular weight 260.7) is formed in the standard sample. The diamide compound and the monoamide compound formed by the reaction of the aromatic carboxylic acid halide with diethylamine are each quantified by the above measurement method. The mass of the quantified diamide compound is divided by 352.5, and the mass of the quantified monoamide compound is divided by 260.7 to calculate the amount of each substance (moles), and then the amounts are added together.

[0035] As a means for reducing the content of aromatic carboxylic acid halide contained in the charge transport layer or the single-layer type photosensitive layer, there is a means for purifying the polyester resin for forming the layer to remove the aromatic carboxylic acid halide. Specifically, there are means for increasing the purity of the monomer as the raw material when polymerizing the polyester resin, for starting the polymerization reaction after sufficiently dissolving the monomer, for setting the concentration of the dicarboxylic acid (specifically, the dicarboxylic acid chloride) in the polymerization reaction system to a low level, and the like. Examples of the method include purifying the polyester resin by reprecipitating it in a solvent (e.g., alcohol) that is a poor solvent for the polyester resin and a good solvent for the aromatic carboxylic acid halide after polymerization of the polyester resin; treating the polyester resin with an amine to decompose the aromatic carboxylic acid halide; and the like.

[0036] The polyester resin having a biphenyl-containing structural unit represented by formula (1) and the aromatic carboxylic acid halide will be described in detail below.

[0037] [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).

[0038] [ka]

[0039] 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.

[0040] 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 R11 are each independently a methyl group or an ethyl group, and are preferably a methyl group.

[0041] 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, further 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.

[0042] 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 dicarboxylic acid unit (1-A) represented by formula (1-A) below and diol unit (1-B) represented by formula (1-B) below, and more preferably has dicarboxylic acid unit (1-A) represented by formula (1-A).

[0043] [ka]

[0044] 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, L A is a single bond or a divalent linking group, Ar A is an aromatic ring which may have a substituent, n A is 0, 1 or 2.

[0045] 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.

[0046] LA 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.

[0047] 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.

[0048] 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 of the aryl group is preferably 6 to 10, and more preferably 6.

[0049] 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.

[0050] Ar AThe aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred. Ar A The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. 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.

[0051] [ka]

[0052] 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, L B is a single bond or a divalent linking group, Ar B is an aromatic ring which may have a substituent, n B is 0, 1 or 2.

[0053] 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.

[0054] L B When R 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 2each independently represents 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; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0055] Rb 1 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.

[0056] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6.

[0057] 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.

[0058] 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, and the benzene ring and the naphthalene ring are preferred. Ar B The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. BWhen 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.

[0059] 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 formula (1-B) is preferably a diol unit (11-B) represented by the following formula (11-B).

[0060] [ka]

[0061] 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.

[0062] j, k, and R in formula (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 formula (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.

[0063] Specific examples of the dicarboxylic acid unit (1-A) include the following dicarboxylic acid units (1-A1) to (1-A10), but the dicarboxylic acid unit (1-A) is not limited thereto.

[0064] [ka]

[0065] As the dicarboxylic acid unit (1-A), at least one selected from the group consisting of dicarboxylic acid units (1-A3) to (1-A7) is preferable, at least one selected from the group consisting of dicarboxylic acid units (1-A3) to (1-A6) is more preferable, and the dicarboxylic acid unit (1-A3) is further preferable.

[0066] Specific examples of the diol unit (1-B) include the following diol units (1-B1) to (1-B10), but the diol unit (1-B) is not limited thereto.

[0067] [ka]

[0068] As the diol unit (1-B), at least one selected from the group consisting of diol units (1-B3) to (1-B7) is preferable, at least one selected from the group consisting of diol units (1-B3) to (1-B6) is more preferable, and the diol unit (1-B3) is further preferable.

[0069] The total mass proportion of the biphenyl-containing structural units represented by formula (1) in the polyester resin (1) is preferably from 15% by mass to 60% by mass, more preferably from 20% by mass to 55% by mass, and even more preferably from 25% by mass to 50% by mass.

[0070] The polyester resin (1) may have a structural unit other than the structural unit containing biphenyl represented by formula (1). Hereinafter, the structural unit other than the structural unit containing biphenyl represented by formula (1) will be described.

[0071] 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).

[0072] 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).

[0073] [ka]

[0074] In formula (A1), n 101 is an integer between 0 and 4, and n 101 Ra 101 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 101 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0075] [ka]

[0076] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 302 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0077] [ka]

[0078] In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401 is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0079] 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 are the same, hereinafter, Ra 101 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0080] The alkyl group having 1 to 10 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of the branched alkyl group having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl group formed by linking these monocyclic alkyl groups.

[0081] The aryl group having 6 to 12 carbon atoms related to Ra may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0082] The alkyl group in the alkoxy group having 1 to 6 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0083] Specific examples of the dicarboxylic acid unit (A1) include the following dicarboxylic acid units (A1-1) to (A1-9), but the dicarboxylic acid unit (A1) is not limited thereto.

[0084] [ka]

[0085] Specific examples of the dicarboxylic acid unit (A3) include the dicarboxylic acid units (A3-1) and (A3-2), but the dicarboxylic acid unit (A3) is not limited thereto.

[0086] [ka]

[0087] Specific examples of the dicarboxylic acid unit (A4) include the following dicarboxylic acid units (A4-1) to (A4-3), but the dicarboxylic acid unit (A4) is not limited thereto.

[0088] [ka]

[0089] 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).

[0090] 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 from 15% by mass to 60% by mass, more preferably from 20% by mass to 55% by mass, and even more preferably from 25% by mass to 50% by mass.

[0091] The polyester resin (1) may have a dicarboxylic acid unit 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 (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid) units, alicyclic dicarboxylic acid (e.g., cyclohexanedicarboxylic acid) units, and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The polyester resin (1) may have one or more types of dicarboxylic acid units.

[0092] 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 following formula (B2), a diol unit (B3) represented by the following formula (B3), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), a diol unit (B6) represented by the following formula (B6), and a diol unit (B8) represented by the following formula (B8).

[0093] When the polyester resin (1) has the diol unit (B), the diol unit (B) may be of one type or of 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); 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) is more preferred, More preferably, the diol unit 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.

[0094] [ka]

[0095] In formula (B1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0096] Rb 101 The carbon number of the branched alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 101 Specific examples of the aryl group include an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0097] [ka]

[0098] In formula (B2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0099] Rb 102 The carbon number of the linear alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples of the aryl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0100] [ka]

[0101] In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0102] 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 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0103] [ka]

[0104] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0105] Rb 104 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 or 2, and more preferably 1. 104 Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0106] [ka]

[0107] In formula (B5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0108] Ar 105 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthracenylmethyl group, and a phenyl-cyclopentylmethyl group.

[0109] [ka]

[0110] 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 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0111] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0112] [ka]

[0113] In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0114] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 201 , Rb 202 , Rb 204 and Rb 205 "Rb 200 " is collectively described as such.

[0115] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably has 1 carbon atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0116] 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 forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 and Rb 408 "Rb 400 " is collectively described as such.

[0117] 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.

[0118] Rb 400 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0119] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0120] 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 forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 501 , Rb 502 , Rb 503 , Rb 504 , Rb505 , Rb 506 and Rb 508 "Rb 500 " is collectively described as such.

[0121] 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.

[0122] Rb 500 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0123] Rb 500Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0124] 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 forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 and Rb 808 "Rb 800 " is collectively described as such.

[0125] 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.

[0126] Rb 800 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0127] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0128] 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 forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 and Rb 908 "Rb 900 " is collectively described as such.

[0129] 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.

[0130] Rb 900 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0131] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0132] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0133] [ka]

[0134] Specific examples of the diol unit (B2) include the diol units (B2-1) to (B2-11), but the diol unit (B2) is not limited thereto.

[0135] [ka]

[0136] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0137] [ka]

[0138] Specific examples of the diol unit (B4) include the diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0139] [ka]

[0140] Specific examples of the diol unit (B5) include the diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0141] [ka]

[0142] Specific examples of the diol unit (B6) include the diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0143] [ka]

[0144] Specific examples of the diol unit (B8) include the diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0145] [ka]

[0146] 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.

[0147] The polyester resin (1) may have a diol unit other than the biphenyl-containing structural unit represented by formula (1) and the diol unit (B). Examples of the other diol units include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol) units and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0148] The ends of the polyester resin (1) may be capped or modified with an end-capping agent or a molecular weight regulator used during production. Examples of the end-capping agent or the molecular weight regulator include a monohydric phenol, a monovalent acid chloride, a monohydric alcohol, and a monovalent carboxylic acid. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m -phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, and 2-phenyl-2-(3-hydroxyphenyl)propane. Examples of the monovalent acid chloride include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetic acid chloride, butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and substituted versions of these. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monovalent carboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0149] The weight average molecular weight of the polyester resin (1) is preferably from 30,000 to 300,000, more preferably from 40,000 to 250,000, and even more preferably from 50,000 to 200,000. The molecular weight of the polyester resin (1) is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (GPC), which uses tetrahydrofuran as an eluent.

[0150] The polyester resin (1) can be obtained by polycondensing a monomer that provides a biphenyl-containing structural unit represented by formula (1), a monomer that provides a dicarboxylic acid unit (A) if necessary, a monomer that provides a diol unit (B), and other monomers if necessary, by a conventional method. Examples of the method for polycondensing monomers include interfacial polymerization, solution polymerization, and melt polymerization. The interfacial polymerization is a polymerization method for obtaining a polyester by mixing a divalent carboxylic acid halide dissolved in an organic solvent that is not compatible with water with a dihydric alcohol dissolved in an aqueous alkali solution. Examples of literature related to the interfacial polymerization include WME ARECSON, J. Poly. Sci., XL399, 1959, and JP-B-1959. The interfacial polymerization has a faster reaction rate than the solution polymerization, and therefore can suppress hydrolysis of the divalent carboxylic acid halide, resulting in a polyester resin with a high molecular weight.

[0151] [Aromatic carboxylic acid halides] The aromatic carboxylic acid halide is generated during the synthesis of the polyester resin and is believed to be carried into the photosensitive layer by the polyester resin used to form the photosensitive layer. Examples of the aromatic carboxylic acid halide include aromatic carboxylic acid fluorides, aromatic carboxylic acid chlorides, aromatic carboxylic acid bromides, and aromatic carboxylic acid iodides.

[0152] The aromatic carboxylic acid halide is, for example, a monohalide or dihalide of a monomer that provides the dicarboxylic acid unit (1-A), for example, a monohalide or dihalide of a monomer that provides the dicarboxylic acid unit (11-A), and for example, a monohalide or dihalide of each of the monomers that provide the dicarboxylic acid units (1-A1) to (1-A10).

[0153] The aromatic carboxylic acid halide is, for example, a monochloride or dichloride of a monomer that provides the dicarboxylic acid unit (1-A), for example, a monochloride or dichloride of a monomer that provides the dicarboxylic acid unit (11-A), and for example, a monochloride or dichloride of each of the monomers that provide the dicarboxylic acid units (1-A1) to (1-A10).

[0154] The aromatic carboxylic acid halide is, for example, a compound represented by the following formula (2).

[0155] [ka]

[0156] In formula (2), p is an integer of 0 to 4, and p R 21 are each independently a methyl group or an ethyl group, q is an integer of 0 to 4, and q R 22 are each independently a methyl group or an ethyl group, r is an integer of 0 to 4, and r R 23 each independently represents a methyl group or an ethyl group, n is 0 or 1, X and Y each independently represent a halogen atom or -OH, and at least one of X and Y is a halogen atom.

[0157] p is an integer of 0 or more and 4 or less, and in one example, an integer of 0 or more and 3 or less, and in one example, an integer of 0 or more and 2 or less, and in one example, 0 or 1, and in one example, 0. When p is an integer equal to or greater than 1, p R 21are each independently a methyl group or an ethyl group, and in one example are each a methyl group.

[0158] q is an integer of 0 or more and 4 or less, and in one example, an integer of 0 or more and 3 or less, and in one example, an integer of 0 or more and 2 or less, and in one example, 0 or 1, and in one example, 0. When q is an integer equal to or greater than 1, q R 22 are each independently a methyl group or an ethyl group, and in one example are each a methyl group.

[0159] r is an integer of 0 or more and 4 or less, and in one example, an integer of 0 or more and 3 or less, and in one example, an integer of 0 or more and 2 or less, and in one example, 0 or 1, and in one example, 0. If r is an integer equal to or greater than 1, then 23 are each independently a methyl group or an ethyl group, and in one example are each a methyl group.

[0160] When X is a halogen atom, X is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. When Y is a halogen atom, Y is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. When X and Y are halogen atoms, X and Y are generally the same type of halogen atom.

[0161] In one embodiment, the aromatic carboxylic acid halide represented by formula (2) is an aromatic carboxylic acid halide represented by the following formula (21).

[0162] [ka]

[0163] In formula (21), n ​​is 0 or 1, X and Y each independently represent a halogen atom or --OH, and at least one of X and Y is a halogen atom. When X is a halogen atom, X is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. When Y is a halogen atom, Y is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. When X and Y are halogen atoms, X and Y are generally the same type of halogen atom.

[0164] In one embodiment, the aromatic carboxylic acid halide includes an aromatic carboxylic acid fluoride. The aromatic carboxylic acid fluoride is, for example, a compound represented by formula (2) or a compound represented by formula (21). In this case, in formula (2) or formula (21), X and Y are each independently a fluorine atom or -OH, and at least one of X and Y is a fluorine atom.

[0165] In the photoreceptor according to the first embodiment, the amount of aromatic carboxylic acid fluoride in the charge transport layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 mol / g or less, preferably 8×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g. In the photoreceptor according to the second embodiment, the amount of aromatic carboxylic acid fluoride in the single-layer photosensitive layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 6×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0166] In one embodiment, the aromatic carboxylic acid halide includes an aromatic carboxylic acid chloride. The aromatic carboxylic acid chloride is, for example, a compound represented by formula (2) or a compound represented by formula (21). In this case, in formula (2) or formula (21), X and Y are each independently a chlorine atom or -OH, and at least one of X and Y is a chlorine atom.

[0167] In the photoreceptor according to the first embodiment, the amount of aromatic carboxylic acid chloride in the charge transport layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 mol / g or less, preferably 8×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g. In the photoreceptor according to the second embodiment, the amount of aromatic carboxylic acid chloride in the single-layer photosensitive layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 6×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0168] In one embodiment, the aromatic carboxylic acid halide includes an aromatic carboxylic acid bromide. The aromatic carboxylic acid bromide is, for example, a compound represented by formula (2) or a compound represented by formula (21). In this case, in formula (2) or formula (21), X and Y are each independently a bromine atom or -OH, and at least one of X and Y is a bromine atom.

[0169] In the photoreceptor according to the first embodiment, the amount of aromatic carboxylic acid bromide in the charge transport layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 mol / g or less, preferably 8×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g. In the photoreceptor according to the second embodiment, the amount of aromatic carboxylic acid bromide in the single-layer photosensitive layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 6×10―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0170] In one embodiment, the aromatic carboxylic acid halide includes an aromatic carboxylic acid iodide. The aromatic carboxylic acid iodide is, for example, a compound represented by formula (2) or a compound represented by formula (21). In this case, in formula (2) or formula (21), X and Y are each independently an iodine atom or -OH, and at least one of X and Y is an iodine atom.

[0171] In the photoreceptor according to the first embodiment, the amount of aromatic carboxylic acid iodide in the charge transport layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 8×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g. In the photoreceptor according to the second embodiment, the amount of aromatic carboxylic acid iodide in the single-layer photosensitive layer is preferably as small as possible from the viewpoint of suppressing the occurrence of burn-in ghosts. ―8 moles / g or less, preferably 6×10 ―8 moles / g or less, more preferably 2×10 ―8 mol / g or less, most preferably 0 mol / g.

[0172] Specific examples of the aromatic carboxylic acid halide represented by formula (2) include the following aromatic carboxylic acid chlorides (2-1-1) to (2-4-2).

[0173] [ka]

[0174] [ka]

[0175] Specific examples of aromatic carboxylic acid fluorides include compounds in which the chlorine atoms in the aromatic carboxylic acid chlorides (2-1-1) to (2-4-2) are replaced with fluorine atoms. Specific examples of aromatic carboxylic acid bromides include compounds in which the chlorine atoms in the aromatic carboxylic acid chlorides (2-1-1) to (2-4-2) are replaced with bromine atoms. Specific examples of aromatic carboxylic acid iodides include compounds in which the chlorine atoms in the aromatic carboxylic acid chlorides (2-1-1) to (2-4-2) are replaced with iodine atoms.

[0176] Each layer of the photoreceptor will now be described in detail.

[0177] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is less than Ωcm.

[0178] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiating with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate since it suppresses the occurrence of defects due to unevenness on the surface.

[0179] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0180] As a method for roughening the surface, there can be mentioned a method in which, without roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0181] In the roughening treatment by anodization, an oxide film is formed on the surface of a conductive substrate made of metal (e.g., aluminum) by anodizing the substrate in an electrolyte solution using the substrate as the anode. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodization is chemically active in its original state, easily contaminated, and has a large resistance variation depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are filled by volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel may be added) to change the film into a more stable hydrated oxide.

[0182] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm. If the thickness is within this range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0183] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acid treatment liquid is carried out, for example, as follows. First, an acid treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acid treatment liquid are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42° C. to 48° C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0184] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the material with heated steam at 90°C to 120°C for 5 to 60 minutes. The thickness of the coating is preferably 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution having low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0185] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0186] For example, inorganic particles have a powder resistance (volume resistivity) of 1×10 2 Ωcm or more 1×10 11 Examples of such particles include inorganic particles with a particle size of Ωcm or less. Among these, examples of inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0187] The specific surface area of ​​inorganic particles by the BET method is, for example, 10 m 2 / g or higher is preferable. The volume average particle size of the inorganic particles is, for example, from 50 nm to 2000 nm (preferably from 60 nm to 1000 nm).

[0188] The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0189] The inorganic particles may be surface-treated. Two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0190] Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum 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.

[0191] 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.

[0192] Silane coupling agents may be used in combination of two or more kinds. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0193] 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.

[0194] The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

[0195] Here, it is preferable that the undercoat layer contains an electron accepting compound (acceptor compound) together with the inorganic particles, from the viewpoints of improving the long-term stability of electrical properties and carrier blocking properties.

[0196] 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. In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and more specifically, anthraquinone, alizarin, quinizarin, anthrarufin, and purpurin.

[0197] 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.

[0198] The method for attaching the electron accepting compound to the surface of the inorganic particles may be, for example, a dry method or a wet method.

[0199] The dry method is, for example, a method in which an electron-accepting compound is attached to the surface of inorganic particles by dropping an electron-accepting compound directly or dissolved in an organic solvent or spraying it together with dry air or nitrogen gas while stirring inorganic particles with a mixer or the like that exerts a large shearing force. The dropping or spraying of the electron-accepting compound is preferably performed at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100° C. or higher. The temperature and time of baking are not particularly limited as long as electrophotographic properties can be obtained.

[0200] The wet method is a method in which, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and the inorganic particles are stirred or dispersed, and then the solvent is removed to attach the electron-accepting compound to the surface of the inorganic particles. The solvent is removed, for example, by filtration or distillation. After the solvent is removed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound, and examples of such methods include a method of removing the moisture while stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0201] The attachment of the electron accepting compound may be carried out before or after the inorganic particles are subjected to a surface treatment with a surface treatment agent, or the attachment of the electron accepting compound and the surface treatment with the surface treatment agent may be carried out simultaneously.

[0202] The content of the electron accepting compound is, for example, from 0.01% by mass to 20% by mass, and preferably from 0.01% by mass to 10% by mass, based on the inorganic particles.

[0203] Examples of the binder resin used in the undercoat layer include known materials 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, phenol 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 the binder resin used in the undercoat layer include charge transporting resins having charge transporting groups, conductive resins (such as polyaniline, etc.), and the like.

[0204] 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, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, and epoxy 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.

[0205] The undercoat layer may contain various additives for improving electrical properties, environmental stability, and image quality. Examples of the additives include known materials such as polycyclic condensation and azo-based electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As described above, silane coupling agents are used for surface treatment of inorganic particles, and may also be added to the undercoat layer as an additive.

[0206] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like.

[0207] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0208] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0209] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0210] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0211] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used in order to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, grinding, and the like.

[0212] The formation of the undercoat layer is not particularly limited, and a known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating solution for forming the undercoat layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary.

[0213] Examples of the solvent for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0214] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming the undercoat layer include known methods such as those using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0215] Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0216] The average thickness of the undercoat layer is preferably from 10 μm to 40 μm, more preferably from 15 μm to 35 μm, and even more preferably from 20 μm to 30 μm.

[0217] [Middle layer] An intermediate layer may further be provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0218] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0219] The formation of the intermediate layer is not particularly limited, and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating solution for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary. The intermediate layer can be formed by any of the usual coating methods, such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating.

[0220] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm The intermediate layer may be used as an undercoat layer.

[0221] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may also be a vapor deposition layer of the charge generation material. The vapor deposition layer of the charge generation material is suitable for use with a non-coherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0222] Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0223] Among these, in order to accommodate laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material, specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine.

[0224] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include condensed aromatic pigments such as dibromoanthanthrone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and bisazo pigments.

[0225] The above charge generating materials may be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm, but 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 a decrease in charging due to charge injection from the substrate, so-called black spots, is likely to occur as an image defect. This becomes more noticeable when using charge generating materials that are p-type semiconductors such as trigonal selenium and phthalocyanine pigments and are prone to generating dark current.

[0226] In contrast, when n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge generating materials, dark current is unlikely to occur, and image defects called black spots can be suppressed even in thin films. The n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and those that are more likely to pass electrons as carriers than holes are considered to be n-type.

[0227] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, and the like. Examples of binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic dicarboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamide resins, acrylic resins, polyacrylamide resins, polyvinylpyridine resins, cellulose resins, urethane resins, epoxy resins, casein, polyvinyl alcohol resins, polyvinylpyrrolidone resins, etc. Here, "insulating" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0228] The compounding ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 by mass.

[0229] The charge generating layer may contain other known additives.

[0230] The formation of the charge generation layer is not particularly limited, and a known formation method is used, for example, by forming a coating film of a coating solution for forming the charge generation layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary. The formation of the charge generation layer may be performed by vapor deposition of the charge generation material. The formation of the charge generation layer by vapor deposition is particularly suitable when a condensed ring aromatic pigment or a perylene pigment is used as the charge generation material.

[0231] Examples of the solvent for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0232] Examples of methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming a charge generating layer include media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion liquid is dispersed by penetrating a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0233] Examples of a method for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0234] The thickness of the charge generating layer is set, for example, preferably in the range of 0.1 μm or more and 5.0 μm or less, and more preferably in the range of 0.2 μm or more and 2.0 μm or less.

[0235] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin, and may be a layer containing a polymer charge transport material.

[0236] Examples of the charge transport material include electron transporting compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of the charge transport material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0237] Examples of the polymer charge transport material include known chemical substances having charge transport properties, such as poly-N-vinylcarbazole and polysilane. For example, a polyester-based polymer charge transport material is preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0238] Examples of the charge transport material or polymer charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, paragraphs 0078 to 0080 of JP 2021-117377 A, paragraphs 0046 to 0048 of JP 2019-035900 A, paragraphs 0052 to 0053 of JP 2019-012141 A, paragraphs 0122 to 0134 of JP 2021-071565 A, and paragraphs 0122 to 0134 of JP 2021-015223 A Examples of the compounds include those described in paragraphs 0101 to 0110 of JP 2013-097300 A, paragraphs 0116 of WO 2019 / 070003 A, paragraphs 0103 to 0107 of JP 2018-159087 A, and paragraphs 0102 to 0113 of JP 2021-148818 A.

[0239] 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).

[0240] [ka]

[0241] 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 ) R T4 , R T5 , R T6 , R T7 and R T8 R is independently a hydrogen atom, an alkyl group, or an aryl group. T5 and R T6 When is an aryl group, the aryl groups are connected to each other by -C(R 51 )(R 52 )- and / or -C(R 61 )=C(R 62 R may be linked to the ring via a divalent group represented by the formula: 51 , R 52 , R 61 and R 62 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0242] 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.

[0243] 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.

[0244] [ka]

[0245] 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.

[0246] [ka]

[0247] In formula (D2), R T201 , R T202 , R T211 and R T212 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ) R T21 , R T22 , R T23 , R T24 and R T25 R is independently a hydrogen atom, an alkyl group, or an aryl group. T221 and R T222 are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2.

[0248] 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.

[0249] 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 an alkyl group, an aryl group, or a -CH=CH-CH=C(R T24 )(R T25 ) is more preferred.

[0250] [ka]

[0251] In formula (D3), R T301 , R T302 , R T311 and R T312 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ) 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.

[0252] 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.

[0253] [ka]

[0254] In formula (D4), R T401 , R T402 , R T411 and R T412 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ) R T41 , R T42 , R T43 , R T44 and R T45 R is independently a hydrogen atom, an alkyl group, or an aryl group. T421 , R T422 and R T431 each independently represents a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, or an alkoxy group having from 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 each independently represent 0, 1, or 2.

[0255] 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.

[0256] The content of the charge transport material in the charge transport layer is preferably 20% by mass or more and 70% by mass or less based on the total mass of the charge transport layer.

[0257] The charge transport layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the charge transport layer is, for example, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass.

[0258] From the viewpoint of superior abrasion resistance, the charge transport layer preferably contains a polyester resin (1) and a polycarbonate resin as binder resins, and in this case, the mass ratio of the two resins, polyester resin (1):polycarbonate resin, is preferably 95:5 to 40:60.

[0259] As the polycarbonate resin, a polycarbonate resin having continuous structural units each having an aromatic ring is preferable, and specifically, the polycarbonate resin used in the examples described later is particularly preferable.

[0260] The charge transport layer may contain other binder resins other than the polyester resin (1) and the polycarbonate resin. Examples of other binder resins include polyester resins other than the polyester resin (1), methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilanes, etc. These binder resins are used alone or in combination of two or more.

[0261] The charge transport layer may contain other known additives, such as an antioxidant, a leveling agent, a defoaming agent, a filler, and a viscosity modifier.

[0262] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0263] Examples of solvents for preparing the coating liquid for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination of two or more.

[0264] Examples of a coating method for coating the coating liquid for forming the charge transport layer on the charge generating layer include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating and curtain coating.

[0265] The average thickness of the charge transport 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.

[0266] [Single-layer photosensitive layer] The single-layer photosensitive layer (charge generation / transport layer) is a layer containing a charge generation material, a charge transport material, a binder resin, and other additives as necessary. These materials are the same as those described for the charge generation layer and the charge transport layer.

[0267] The single-layer photosensitive layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the single-layer photosensitive layer is, for example, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass.

[0268] From the viewpoint of superior abrasion resistance, the single-layer type photosensitive layer preferably contains a polyester resin (1) and a polycarbonate resin as binder resins. In this case, the mass ratio of the two resins, polyester resin (1):polycarbonate resin, is preferably 95:5 to 40:60.

[0269] As the polycarbonate resin, a polycarbonate resin having continuous structural units each having an aromatic ring is preferable, and specifically, the polycarbonate resin used in the examples described later is particularly preferable.

[0270] In the single-layer photosensitive layer, the content of the charge generating material is preferably from 0.1% by mass to 10% by mass, more preferably from 0.8% by mass to 5% by mass, based on the total solid content.

[0271] The content of the charge transport material in the single-layer photosensitive layer is preferably 40% by mass or more and 60% by mass or less based on the total solid content.

[0272] The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer.

[0273] 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.

[0274] [Protective layer] A protective layer is provided on the photosensitive layer as necessary for the purpose of, for example, preventing chemical changes in the photosensitive layer when the photosensitive layer is charged and further improving the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a layer composed of a cured film (crosslinked film) as the protective layer. Examples of such a layer include the following layers 1) and 2).

[0275] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer containing a polymer or crosslinked product of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material that does not have a charge transport skeleton and has a reactive group (i.e., a layer containing a non-reactive charge transport material and a polymer or crosslinked body of the reactive group-containing non-charge transport material).

[0276] The reactive group of the reactive group-containing charge transport material may be a chain polymerizable group, an epoxy group, -OH, -OR (wherein R represents an alkyl group), -NH2, -SH, -COOH, or -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group; R Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group; Qn represents an integer of 1 to 3.

[0277] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond.Specific examples include a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof.Among them, the chain polymerizable group is preferably a group containing at least one selected from a vinyl group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof, because of its excellent reactivity.

[0278] The charge transporting skeleton of the reactive group-containing charge transporting material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors, and examples thereof include a skeleton derived from a nitrogen-containing hole transporting compound such as a triarylamine compound, a benzidine compound, a hydrazone compound, etc., and a structure conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0279] 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.

[0280] The protective layer may contain other known additives.

[0281] 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 solution for forming a protective layer in which the above components are added to a solvent, drying the coating film, and, if necessary, subjecting it to a curing treatment such as heating.

[0282] Examples of solvents for preparing a coating solution for forming a protective layer include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as tetrahydrofuran and dioxane, cellosolve solvents such as ethylene glycol monomethyl ether, and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more. The coating liquid for forming the protective layer may be a solvent-free coating liquid.

[0283] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (e.g., a charge transport layer) include conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0284] The thickness of the protective layer is set, for example, preferably in the range of 1 μm or more and 20 μm or less, and more preferably in the range of 2 μm or more and 10 μm or less.

[0285] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging device that charges the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer device that transfers the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

[0286] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus provided with a fixing device which fixes a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type which 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 which 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 provided with a cleaning device which cleans the surface of an electrophotographic photosensitive member before charging after the transfer of a toner image; an apparatus provided with a static elimination device which irradiates the surface of an electrophotographic photosensitive member with static elimination light to eliminate static electricity before charging after the transfer of a toner image; and an apparatus provided with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0287] In the case of an intermediate transfer type device, the transfer device is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer device which primarily transfers the toner image formed on the surface of an electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer device which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0288] The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0289] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. The process cartridge may include, in addition to the electrophotographic photosensitive member, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0290] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Principal parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0291] FIG. 3 is a schematic diagram showing an example of an image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, and the intermediate transfer body 50 is disposed with a part of it in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer device.

[0292] 3 supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) integrally within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0293] FIG. 3 shows an example of an image forming apparatus including a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of the electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists in cleaning, which are arranged as needed.

[0294] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0295] -Charging device- As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also, a non-contact type roller charger, a scorotron charger or corotron charger that utilizes corona discharge, or other chargers known per se, can be used.

[0296] -Exposure equipment- The exposure device 9 may be, for example, an optical device that exposes the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. The wavelength of the semiconductor laser is mainly near infrared light having an oscillation wavelength of about 780 nm. However, it is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a blue laser having an oscillation wavelength of 400 nm to 450 nm may also be used. In addition, a surface-emitting laser light source capable of outputting multiple beams is also effective for forming a color image.

[0297] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contacting or non-contacting a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected according to the purpose. For example, it may be a known developing device that has a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, roller, or the like. Among them, it is preferable to use a developing roller that holds a developer on its surface.

[0298] The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Known developers are used.

[0299] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning type or a simultaneous development and cleaning type may also be adopted.

[0300] -Transfer device- Examples of the transfer device 40 include known transfer chargers such as a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0301] -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.

[0302] FIG. 4 is a schematic diagram showing another example of the image forming apparatus according to the present embodiment. 4 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photosensitive body is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. EXAMPLES

[0303] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, unless otherwise specified, synthesis, production, processing, measurement, etc. were carried out at room temperature (25° C.±3° C.).

[0304] <Synthesis of polyester resin> [Synthesis of polyester resin (PE-1-1)] -Polymerization reaction- 400 ml of distilled water and 3.60 g of sodium hydroxide were added to a 1 L separable flask (container A) to prepare an aqueous solution of sodium hydroxide. 11.04 g of 4,4'-(2-ethylhexylidene)diphenol and 0.16 g of 2,3,6-trimethylphenol were added to the aqueous solution of sodium hydroxide and completely dissolved. 0.05 g of benzyltributylammonium chloride was then added as a phase transfer catalyst. Into a 1 L three-neck flask (container B), 200 ml of methylene chloride and 10.50 g of 4,4'-biphenyldicarbonyl chloride were placed and mixed with stirring. The solution in vessel B was transferred to vessel A over 30 minutes using a liquid transfer pump. When vessel B was empty, 50 ml of methylene chloride was added to vessel B, and the entire liquid in vessel B was transferred to vessel A. Thereafter, stirring in vessel A was continued for 2 hours to allow the polymerization reaction to proceed.

[0305] -Cleaning- Next, the aqueous layer in the vessel A was removed, and 300 ml of methylene chloride was added to the organic layer, and further 50 ml of methanol was added, and stirring was continued for 2 hours. The organic layer was then repeatedly washed with distilled water until the pH of the organic layer became neutral. The methylene chloride was then distilled off under reduced pressure to obtain a polyester resin (PE-1-1).

[0306] [Synthesis of polyester resin (PE-1-2)] The polymerization reaction was carried out in the same manner as above. Next, the aqueous layer in vessel A was removed, and 300 ml of methylene chloride was added to the organic layer, and further 50 ml of methanol was added, and stirring was continued for 30 minutes. The organic layer was then repeatedly washed with distilled water until the pH of the organic layer became neutral. The methylene chloride was then distilled off under reduced pressure to obtain a polyester resin (PE-1-2).

[0307] [Synthesis of polyester resin (PE-1-3)] The polymerization reaction was carried out in the same manner as above. Next, the aqueous layer in the container A was removed, and the organic layer was repeatedly washed with distilled water until the pH of the organic layer became neutral. Next, methylene chloride was distilled off under reduced pressure to obtain a polyester resin (PE-1-3).

[0308] [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 the polyester resins (PE-1-1) to (PE-1-3), except that the type of monomer used in the polymerization reaction was changed. Here, x is an integer of 2 to 7, and y is an integer of 1 to 3. The polyester resin (PE-x-1) was obtained by carrying out the same purification treatment as for the polyester resin (PE-1-1). The polyester resin (PE-x-2) was obtained by carrying out the same purification treatment as for the polyester resin (PE-1-2). The polyester resin (PE-x-3) was obtained by carrying out the same treatment as for the polyester resin (PE-1-3).

[0309] 1-A3 and the like shown in Table 1 are specific examples of the above-mentioned dicarboxylic acid unit (1-A). A3-2 and the like in Table 1 are specific examples of the above-mentioned dicarboxylic acid unit (A). B1-4 and the like shown in Table 1 are specific examples of the diol unit (B) described above. When there are two types of dicarboxylic acid units, Table 1 also shows the composition ratio (mol %).

[0310] [Table 1]

[0311] <Production of a photoreceptor having a laminated photosensitive layer> [Example S1] - Formation of undercoat layer - Zinc oxide (average particle size 70 nm, specific surface area 15 m 2100 parts of a silane coupling agent (product name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added to the mixture 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.

[0312] 110 parts of the surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran by stirring, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added thereto, followed by stirring for 5 hours at 50° C. Thereafter, the solid content was filtered off by reduced pressure filtration and dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin added thereto.

[0313] 100 parts of a solution of 60 parts of alizarin-added zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, product name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts of butyral resin (product name: S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) dissolved in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone, and the mixture was dispersed for 2 hours in a sand mill using glass beads with a diameter of 1 mm to obtain a dispersion. 0.005 parts of dioctyltin dilaurate as a catalyst and 4 parts of silicone resin particles (product name: Tospearl 145, manufactured by Momentive Performance Materials Co., Ltd.) were added to the dispersion to obtain a coating liquid for forming an undercoat layer. The coating solution for forming the undercoat layer was applied to the outer surface of a conductive substrate (a cylindrical aluminum tube having an outer diameter of 30 mm, a length of 365 mm, and a thickness of 1.6 mm) by dip coating, and the coating was dried and cured at 185° C. for 35 minutes to form an undercoat layer. The average thickness of the undercoat layer was 25 μm.

[0314] - Formation of charge generation layer - A mixture of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generating material, 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature to form a charge generating layer with an average thickness of 0.25 μm.

[0315] - 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 of tetrahydrofuran and 50 parts of toluene to obtain a coating solution for forming a charge transport layer. The coating solution for forming a charge transport layer was dip-coated on the charge generating 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.

[0316] [ka]

[0317] [Examples S2 to S27, Comparative Examples SC1 to SC9] Each photoreceptor was prepared in the same manner as in Example S1, except that the type of polyester resin used in forming the charge transport layer was changed to the type shown in Table 2. In Examples S15 to S27 and Comparative Examples SC8 to SC9, a part of the polyester resin was replaced with a polycarbonate resin. The structures of the polycarbonate resins (1) to (3) are as follows:

[0318] [ka]

[0319] <Production of a photoreceptor having a single-layer type photosensitive layer> [Example T1] - Formation of photosensitive layer - Binder resin: Polyester resin (PE-1-1) 45 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) 1.0 part ·Electron transport material: ETM-1 ···9 parts ·Charge transport material: CTM-1 ···45 parts The above materials were dissolved or dispersed in a mixed solvent of 175 parts of tetrahydrofuran and 75 parts of toluene, and dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours to obtain a coating solution for forming a photosensitive layer. The coating solution for forming a photosensitive layer was applied to the outer surface of a conductive substrate (a cylindrical aluminum tube with an outer diameter of 30 mm, a length of 365 mm, and a thickness of 1.6 mm) by a dip coating method, and dried at a temperature of 150°C for 60 minutes to form a single-layer type photosensitive layer with an average thickness of 36 μm.

[0320] [ka]

[0321] [Examples T2 to T3, Comparative Example TC1] In the same manner as in Example T1, except that the type of polyester resin was changed to the type shown in Table 3, each photoreceptor was produced. In Example T3, a part of the polyester resin was replaced with polycarbonate resin (1), the structure of which was as described above.

[0322] <Photoreceptor performance evaluation> The photoreceptor of each of the examples and comparative examples was mounted on an electrophotographic image forming apparatus Apeos C7070 (FUJIFILM Business Innovation Co., Ltd.).

[0323] [Wear resistance] In a low-temperature, low-humidity environment with a temperature of 10°C and a relative humidity of 15%, full-surface halftone images (images with a density of 30%) were continuously printed on A3-sized plain paper for 10,000 sheets each of yellow, magenta, cyan, and black, for a total of 40,000 sheets. The average thickness (nm) of the charge transport layer or single-layer photosensitive layer was measured before and after this image formation, and the difference in the average thickness before and after image formation was taken as the amount of wear (nm). A Permascope manufactured by Fisher Instruments was used as the film thickness measuring device. The amount of wear was classified as follows. The results are shown in Tables 2 and 3. A: Abrasion amount is less than 800 nm B: Abrasion amount is 800nm ​​or more and less than 1600nm C: Wear amount is 1600nm or more

[0324] [Burned-in ghost] In a high-temperature and high-humidity environment with a temperature of 28°C and a relative humidity of 85%, 500 sheets of grid charts (black) were printed continuously on A3-size plain paper, and then one full-surface halftone image (30% density image, black) was output. The full-surface halftone images were visually observed and classified as follows. The results are shown in Tables 2 and 3. A: No lattice-like image (burn-in ghost image) is visible. B: A faint grid-like image (burn-in ghost image) is visible. C: A grid-like image (burn-in ghost image) is clearly visible.

[0325] [Table 2]

[0326] [Table 3]

[0327] 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.

[0328] (((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 polyester resin having a structural unit containing biphenyl represented by formula (1), The amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 moles / g or less, Electrophotographic photoreceptor. (((2))) The amount of aromatic carboxylic acid halide in the charge transport layer is 8×10 per unit mass of the charge transport layer. ―8 mol / g or less. (((3))) The electrophotographic photoreceptor according to (((1))) or (((2))), wherein the aromatic carboxylic acid halide is a compound represented by formula (2). (((4))) The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein the aromatic carboxylic acid halide includes an aromatic carboxylic acid chloride. (((5))) The electrophotographic photoreceptor according to any one of (((1))) to (((4))), wherein the charge transport layer further contains a polycarbonate resin. (((6))) The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein 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). (((7))) The electrophotographic photoreceptor according to any one of (((1))) to (((6))), wherein the polyester resin has at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). (((8))) The electrophotographic photoreceptor according to any one of (((1))) to (((7))), wherein the polyester resin has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), and a diol unit (B8) represented by formula (B8). (((9))) A conductive substrate and a single-layer type photosensitive layer disposed on the conductive substrate, the single-layer type photosensitive layer contains a polyester resin having a structural unit containing biphenyl represented by formula (1), The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 moles / g or less, Electrophotographic photoreceptor. (((10))) The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 6×10 ―8 mol / g or less. (((11))) The electrophotographic photoreceptor according to (((9))) or (((10))), wherein the aromatic carboxylic acid halide is a compound represented by formula (2): (((12))) The electrophotographic photoreceptor according to any one of (((9))) to (((11))), wherein the aromatic carboxylic acid halide includes an aromatic carboxylic acid chloride. (((13))) The electrophotographic photoreceptor according to any one of (((9))) to (((12))), wherein the single-layer type photosensitive layer further contains a polycarbonate resin. (((14))) The electrophotographic photoreceptor according to any one of (((9))) to (((13))), wherein 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). (((15))) The electrophotographic photoreceptor according to any one of (((9))) to (((14))), wherein the polyester resin has at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). (((16))) The electrophotographic photoreceptor according to any one of (((9))) to (((15))), wherein the polyester resin has at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), and a diol unit (B8) represented by formula (B8). (((17))) An electrophotographic photoreceptor according to any one of (((1))) to (((16))), A process cartridge that is detachably attached to an image forming apparatus. (((18))) An electrophotographic photoreceptor according to any one of (((1))) to (((16))); a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

[0329] According to the invention of (((1)), (((3)), (((4)), (((5)), (((6)), (((7))) or (((8)), in an electrophotographic photoreceptor having a multi-layer photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. According to the invention of (((2)), in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 8×10 per unit mass of the charge transport layer. ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. According to the invention of (((9)), (((11)), (((12)), (((13)), (((14)), (((15))) or (((16)), in an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. According to the invention of (((10))), in an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 6×10 ―8 As compared with the case where the content exceeds mol / g, an electrophotographic photoreceptor which is excellent in abrasion resistance and which is less susceptible to image burn-in ghost is provided. According to the invention of (((17))), in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 or in the case of an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8As compared with the case where the content exceeds mol / g, a process cartridge is provided which has excellent abrasion resistance of an electrophotographic photosensitive member and is less susceptible to ghost marks on images. According to the invention of (((18))), in an electrophotographic photoreceptor having a laminated photosensitive layer, the amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. ―8 or in the case of an electrophotographic photoreceptor having a single-layer type photosensitive layer, the amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 ―8 As compared with the case where the content exceeds mol / g, an image forming apparatus is provided in which the abrasion resistance of the electrophotographic photoreceptor is excellent and image burn-in ghosts are less likely to occur in the image. [Explanation of symbols]

[0330] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0331] 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 polyester resin having a structural unit containing biphenyl represented by the following formula (1), The amount of aromatic carboxylic acid halide in the charge transport layer is 15×10 per unit mass of the charge transport layer. －８ moles / g or less; Electrophotographic photoreceptor. 【Chemistry 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. The amount of aromatic carboxylic acid halide in the charge transport layer is 8×10 per unit mass of the charge transport layer. －８ 2. The electrophotographic photoreceptor according to claim 1, wherein the molecular weight is 1.0 mol / g or less.

3. 2. The electrophotographic photoreceptor according to claim 1, wherein the aromatic carboxylic acid halide is a compound represented by the following formula (2): 【Chemistry 2】 In formula (2), p is an integer of 0 to 4, and p R ２１ are each independently a methyl group or an ethyl group, q is an integer of 0 to 4, and q R ２２ are each independently a methyl group or an ethyl group, r is an integer of 0 to 4, and r R ２３ each independently represents a methyl group or an ethyl group, n is 0 or 1, X and Y each independently represent a halogen atom or --OH, and at least one of X and Y is a halogen atom.

4. 2. The electrophotographic photoreceptor of claim 1, wherein the aromatic carboxylic acid halide comprises an aromatic carboxylic acid chloride.

5. 2. The electrophotographic photoreceptor of claim 1, wherein the charge transport layer further comprises a polycarbonate resin.

6. The electrophotographic photoreceptor according to claim 1, wherein 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). 【Chemistry 3】 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; L Ａ is a single bond or a divalent linking group, Ar Ａ represents an aromatic ring which may have a substituent; 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; L Ｂ is a single bond or a divalent linking group, Ar Ｂ represents an aromatic ring which may have a substituent; n Ｂ is 0, 1 or 2.

7. 7. The electrophotographic photoreceptor according to claim 6, wherein the polyester resin has at least one 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). 【Chemistry 4】 In formula (A1), n １０１ is an integer of 0 to 4, １０１ Ra １０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

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

9. A conductive substrate and a single-layer type photosensitive layer disposed on the conductive substrate, the single-layer photosensitive layer contains a polyester resin having a structural unit containing biphenyl represented by the following formula (1), The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 15×10 per unit mass of the single-layer type photosensitive layer. ―８ moles / g or less; Electrophotographic photoreceptor. 【Chemistry 7】 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.

10. The amount of aromatic carboxylic acid halide in the single-layer type photosensitive layer is 6×10 per unit mass of the single-layer type photosensitive layer. ―８ The electrophotographic photoreceptor according to claim 9, wherein the molecular weight is 1.0 mol / g or less.

11. The electrophotographic photoreceptor according to claim 9 , wherein the aromatic carboxylic acid halide is a compound represented by the following formula (2): 【Chemistry 8】 In formula (2), p is an integer of 0 to 4, and p R ２１ are each independently a methyl group or an ethyl group, q is an integer of 0 to 4, and q R ２２ are each independently a methyl group or an ethyl group, r is an integer of 0 to 4, and r R ２３ each independently represents a methyl group or an ethyl group, n is 0 or 1, X and Y each independently represent a halogen atom or --OH, and at least one of X and Y is a halogen atom.

12. 10. The electrophotographic photoreceptor according to claim 9, wherein the aromatic carboxylic acid halide comprises an aromatic carboxylic acid chloride.

13. The electrophotographic photoreceptor according to claim 9 , wherein the single-layer type photosensitive layer further contains a polycarbonate resin.

14. The electrophotographic photoreceptor according to claim 9, wherein 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). 【Chemistry 9】 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; L Ａ is a single bond or a divalent linking group, Ar Ａ represents an aromatic ring which may have a substituent; 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; L Ｂ is a single bond or a divalent linking group, Ar Ｂ represents an aromatic ring which may have a substituent; n Ｂ is 0, 1 or 2.

15. The electrophotographic photoreceptor according to claim 14, wherein the polyester resin has at least one 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). 【Chemistry 10】 In formula (A1), n １０１ is an integer of 0 to 4, １０１ Ra １０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

16. 15. The electrophotographic photoreceptor according to claim 14, wherein the polyester resin has at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B3) represented by the following formula (B3), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), a diol unit (B6) represented by the following formula (B6), and a diol unit (B8) represented by the following formula (B8). 【Chemistry 11】 【Chemistry 12】 In formula (B1), Rb １０１ is a branched alkyl group having 4 to 20 carbon atoms, Rb ２０１ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; Rb ４０１ , Rb ５０１ , Rb ８０１ and Rb ９０１ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B2), Rb １０２ is a linear alkyl group having 4 to 20 carbon atoms; Rb ２０２ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; Rb ４０２ , Rb ５０２ , Rb ８０２ and Rb ９０２ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B3), Rb １１３ and Rb ２１３ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; ４０３ , Rb ５０３ , Rb ８０３ and Rb ９０３ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B4), Rb １０４ and Rb ２０４ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; ４０４ , Rb ５０４ , Rb ８０４ and Rb ９０４ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B5), Ar １０５ is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, Rb ２０５ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, Rb ４０５ , Rb ５０５ , Rb ８０５ and Rb ９０５ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B6), Rb １１６ and Rb ２１６ are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb ４０６ , Rb ５０６ , Rb ８０６ and Rb ９０６ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B8), Rb ４０８ , Rb ５０８ , Rb ８０８ and Rb ９０８ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

17. The electrophotographic photoreceptor according to any one of claims 1 to 16 is provided, A process cartridge that is detachably attached to an image forming apparatus.

18. The electrophotographic photoreceptor according to any one of claims 1 to 16, a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

Images