Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that is excellent in thin line reproducibility and wear resistance.SOLUTION: An electrophotographic photoreceptor comprises a conductive substrate, and a photosensitive layer arranged on the conductive substrate. An outermost surface layer is a layer containing a charge transport material and a binder resin and having a breaking energy of 10 mJ / mm3 or more. An outer peripheral surface has a coefficient of dynamic friction of 0.5 or more and 1.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a cleaning device for cleaning a movable photosensitive drum of an image forming device that forms an image on a recording sheet, the cleaning device having a cleaning member that contacts the photosensitive drum to remove toner remaining on the photosensitive drum, and the cleaning device has a dynamic friction coefficient between the surface layer of the photosensitive drum and the cleaning member that is in the range of dynamic friction coefficient ≦0.9 measured at a scanning speed of 50 mm / min and dynamic friction coefficient measured at a scanning speed of 3 mm / min ≦dynamic friction coefficient measured at a scanning speed of 50 mm / min × 1.1 when the amount of wear of the surface layer of the photosensitive drum measured with a Taber abrasion tester is 1.5 mg or less.

[0003] Patent Document 2 discloses an image forming method for forming a large number of images by repeating the steps of charging, image exposure, development, transfer, and cleaning with a cleaning blade on an electrophotographic photosensitive member, in which the static friction coefficient of the photosensitive member against the cleaning blade is set to 1.0 or less, the cleaning blade is brought into contact with the photosensitive member in a counter direction, and the cleaning is performed by vibrating the cleaning blade with a vibration magnitude of 10 to 200 μm.

[0004] Patent Document 3 discloses an image forming method including a step of applying a uniform charge onto a traveling electrophotographic photoreceptor, a step of forming an electrostatic latent image by imagewise exposure, and each of the steps of development, transfer, and cleaning, in which a photoreceptor having a photosensitive layer containing an organic photoconductive substance is used as the photoreceptor, a rubber elastic cleaning blade having a repulsive elasticity of 35 to 75% is used as the cleaning member in the cleaning step, the cleaning blade is brought into contact with the photoreceptor at an angle in the counter direction, and the static friction coefficient of the photoreceptor surface layer against the cleaning blade is set to be in the range of 0.1 to 1.0. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-333804 A [Patent Document 2] Japanese Patent Application Publication No. 09-090843 [Patent Document 3] Japanese Patent Application Publication No. 08-083028 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure relates to a method for manufacturing a semiconductor device having a surface layer with a fracture energy of 10 mJ / mm 3 The present invention aims to provide an electrophotographic photoreceptor which is excellent in fine line reproducibility and abrasion resistance as compared with a case in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0. [Means for solving the problem]

[0007] 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.

[0008] <1> A conductive substrate and a photosensitive layer disposed on the conductive substrate, The outermost layer contains a charge transport material and a binder resin, and the breaking energy is 10 mJ / mm 3 These are the layers above. The dynamic friction coefficient of the outer circumferential surface is 0.5 or more and 1.0 or less. Electrophotographic photoreceptor. <2> The coefficient of dynamic friction is expressed as the breaking energy (mJ / mm 3 ) is between 0.05 and 0.10. <1> The electrophotographic photoreceptor according to claim 1. <3> The binder resin contains a polyester resin, and the proportion of the polyester resin in the binder resin is 35% by mass or more and 75% by mass or less. <1> or <2> The electrophotographic photoreceptor according to claim 1. <4> The proportion of the binder resin in the outermost layer is 50% by mass or more. <1> ~ <3> 13. The electrophotographic photoreceptor according to claim 12, <5> The proportion of the binder resin in the outermost layer is 55% by mass or more and 70% by mass or less. <1> ~ <4> 13. The electrophotographic photoreceptor according to claim 12, <6> The binder resin contains two or more resins. <1> ~ <5> 13. The electrophotographic photoreceptor according to claim 12, <7> The two or more resins include a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). <6> The electrophotographic photoreceptor according to claim 1. <8> The dicarboxylic acid unit (A) represented by the formula (A) includes at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3), and a dicarboxylic acid unit (A4) represented by the formula (A4). <7> The electrophotographic photoreceptor according to claim 1. <9> The diol unit (B) represented by the formula (B) includes at least one selected from the group consisting of a diol unit (B1) represented by the formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8). <7> or <8> The electrophotographic photoreceptor according to claim 1. <10> The two or more resins include a polycarbonate resin. <6> ~ <9> 13. The electrophotographic photoreceptor according to claim 12, <11> the photosensitive layer has a charge generating layer and a charge transport layer, and the charge transport layer is the outermost layer; <1> ~ <10> 13. The electrophotographic photoreceptor according to claim 12, <12> <1> ~ <11> and an electrophotographic photoreceptor according to any one of the above items. a charging device for charging a surface of the electrophotographic photosensitive member, the charging device having a charging member in direct contact with the electrophotographic photosensitive member and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; A process cartridge that is detachably attached to an image forming apparatus. <13> <1> ~ <11> and an electrophotographic photoreceptor according to any one of the above items. a charging device for charging a surface of the electrophotographic photoreceptor, the charging device having a charging member that is in direct contact with the electrophotographic photoreceptor and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; 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; A cleaning device that cleans the surface of the electrophotographic photoreceptor. Image forming device. Effect of the Invention

[0009] <1> or <11> According to the study, the fracture energy of the outermost layer is 10 mJ / mm 3 In comparison with a case in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0, an electrophotographic photoreceptor excellent in thin-line reproducibility and abrasion resistance is provided. <2> According to this, an electrophotographic photoreceptor is provided which is excellent in fine line reproducibility and abrasion resistance, as compared with a case in which the value obtained by dividing the dynamic friction coefficient by the breaking energy is less than 0.05 or exceeds 0.10. <3> According to this, an electrophotographic photoreceptor having excellent fine line reproducibility and abrasion resistance is provided, as compared with a case in which the proportion of the polyester resin in the binder resin is less than 35% by mass or more than 75% by mass. <4> According to this, an electrophotographic photoreceptor having excellent fine line reproducibility and abrasion resistance is provided, as compared with a case in which the proportion of the binder resin in the outermost layer is less than 50% by mass. <5> According to this, an electrophotographic photoreceptor having excellent fine line reproducibility and abrasion resistance is provided, as compared with a case in which the proportion of the binder resin in the outermost layer is less than 55% by mass or more than 70% by mass. <6> , <7> , <8> , <9> or <10> According to this, an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, as compared with a case in which the binder resin is one type of resin. <12> According to the , the breaking energy of the outermost layer of the electrophotographic photoreceptor is 10 mJ / mm 3 The present invention provides a process cartridge having an electrophotographic photosensitive member which is excellent in thin-line reproducibility and wear resistance compared to a case in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0. <13> According to the , the breaking energy of the outermost layer of the electrophotographic photoreceptor is 10 mJ / mm 3 The present invention provides an image forming apparatus equipped with an electrophotographic photoreceptor which is excellent in fine line reproducibility and wear resistance compared to an electrophotographic photoreceptor in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photoreceptor according to the present embodiment. [Diagram 2] FIG. 4 is a partial cross-sectional view showing another example of the layer structure of the electrophotographic photoreceptor according to the present embodiment. [Diagram 3] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. 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

[0011] 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.

[0012] 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.

[0013] In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0014] When 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.

[0015] 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.

[0016] In the present disclosure, unless otherwise specified, the alkyl group and the alkylene group include any of straight-chain, branched, and cyclic groups. 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. 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 electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") according to this embodiment includes a conductive substrate and a photosensitive layer disposed on the conductive substrate.

[0019] FIG. 1 is a partial cross-sectional view that shows an example of the layer structure of the photoreceptor according to the present embodiment. The photoreceptor 10A shown in FIG. 1 has a laminated photosensitive layer. The photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called function-separated photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3. The photoreceptor 10A may have a protective layer (not shown) on the photosensitive layer 5. The undercoat layer 2 may or may not be present.

[0020] Fig. 2 is a partial cross-sectional view that shows a schematic example of another example of the layer structure of the photoreceptor according to the present embodiment. The photoreceptor 10B shown in Fig. 2 has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are laminated in this order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5. The photoreceptor 10B may have a protective layer (not shown) on the photosensitive layer 5. The undercoat layer 2 may or may not be present.

[0021] The photoreceptor according to the present embodiment has an outermost layer containing a charge transport material and a binder resin and a breaking energy of 10 mJ / mm3 The coefficient of dynamic friction of the outer peripheral surface is 0.5 to 1.0. The outer peripheral surface is the exposed surface of the outermost layer.

[0022] An example of an embodiment of the photoreceptor has a laminated photosensitive layer in which a charge generating layer and a charge transport layer are laminated, and the charge transport layer is the outermost layer. Another example of an embodiment of the photoreceptor has a single-layer type photosensitive layer, and the single-layer type photosensitive layer is the outermost layer. Another example of an embodiment of the photoreceptor has a protective layer on the multi-layer type photosensitive layer or the single-layer type photosensitive layer, and the protective layer is the outermost layer.

[0023] Fracture energy of the outermost layer (mJ / mm 3 The measurement method for is as follows. The outermost layer is peeled off from the photoreceptor and cut into a square of 50 mm on each side. The thickness of the outermost layer after peeling is measured. The square is cut into a rectangle of 5 mm width x 25 mm length to create 10 samples. The samples are fixed to the testing machine and measurements are performed under the following measurement conditions. Measuring device: MODEL-1605N (Aiko Engineering Co., Ltd.) Measurement conditions: Load and displacement were measured at a tensile speed of 20 mm / min. Measurement interval was 0.1. Measurements: 10 times (10 samples) The breaking energy is calculated from the integral of the stress (Pa) and strain up to the break. The measurement results of 10 samples are arithmetically averaged.

[0024] The dynamic friction coefficient of the outer peripheral surface of the photoreceptor is measured as follows. A sapphire probe is brought into contact with the photoconductor. The dynamic friction coefficient is calculated from the average value of the friction coefficients after 15 reciprocations at a moving distance of 10 mm and a moving speed of 10 mm / sec.

[0025] The photoconductor according to this embodiment has a breaking energy of 10 mJ / mm 3 When the dynamic friction coefficient of the outer peripheral surface is 0.5 or more and 1.0 or less, excellent fine line reproducibility and abrasion resistance are achieved. It has been known that a filler having lubricating properties is contained in the outermost layer of a photoreceptor in order to suppress wear of the photoreceptor. However, the filler in the outermost layer may lead to a decrease in image quality (e.g., a decrease in fine line reproducibility). The present inventors have conducted extensive research and have found that the outermost layer has excellent abrasion resistance without relying on a filler. The photoreceptor according to this embodiment does not require the outermost layer to contain a filler, and therefore has excellent fine line reproducibility.

[0026] The breaking energy of the outermost layer of the photoconductor is 10 mJ / mm 3 If the surface tension is less than 10 mJ / mm, the wear of the photoconductor is accelerated, and the wear variation of the photoconductor increases, resulting in uneven density. 3 More than 12 mJ / mm 3 More preferably, it is equal to or greater than this. The upper limit of the breaking energy of the outermost layer of the photoconductor is, for example, 50 mJ / mm 3 For example, 45 mJ / mm 3 For example, 30 mJ / mm 3 The following is the result.

[0027] If the dynamic friction coefficient of the outer peripheral surface of the photoreceptor is less than 0.5, the toner cannot be sufficiently stopped by the cleaning blade, causing contamination of the charging member. From the viewpoint of suppressing this phenomenon, the dynamic friction coefficient of the outer peripheral surface of the photoreceptor is 0.5 or more, preferably 0.55 or more, more preferably 0.6 or more, and even more preferably 0.65 or more. If the dynamic friction coefficient of the outer peripheral surface of the photoreceptor exceeds 1.0, problems such as an increased motor load during image formation and turning over of the cleaning blade occur. From the viewpoint of suppressing these phenomena, the dynamic friction coefficient of the outer peripheral surface of the photoreceptor is 1.0 or less, and preferably 0.8 or less.

[0028] The coefficient of dynamic friction of the outer peripheral surface of the photoreceptor is expressed as the rupture energy (mJ / mm 3From the viewpoint of reducing the wear rate, the value obtained by dividing the coefficient of dynamic friction by the energy to break (dynamic friction coefficient / breaking energy) is preferably 0.01 or more and 0.10 or less, and more preferably 0.03 or more and 0.08 or less.

[0029] The breaking energy of the outermost layer of the photoconductor and the dynamic friction coefficient of the outer peripheral surface of the photoconductor are controlled by the type and combination of resins constituting the binder resin of the outermost layer and the content of the resin. A preferred embodiment of the binder resin is described below.

[0030] From the viewpoint of abrasion resistance of the outermost layer, the outermost layer of the photoreceptor preferably contains a polyester resin as a binder resin, and the proportion of the polyester resin in the binder resin is preferably 20% by mass or more and 80% by mass or less. When the proportion of the polyester resin in the binder resin is 20% by mass or more, the wear variation is reduced. From this viewpoint, the proportion of the polyester resin in the binder resin is more preferably 25% by mass or more, further preferably 30% by mass or more, and further preferably 35% by mass or more. When the proportion of the polyester resin in the binder resin is 80% by mass or less, the cleaning property becomes good. From this viewpoint, the proportion of the polyester resin in the binder resin is more preferably 75% by mass or less.

[0031] From the viewpoint of the abrasion resistance of the outermost layer, the outermost layer of the photoreceptor preferably contains polyester resin (1) as a binder resin, and the proportion of polyester resin (1) in the binder resin is preferably 20% by mass or more and 80% by mass or less. The proportion of the polyester resin (1) in the binder resin is more preferably 25% by mass or more, further preferably 30% by mass or more, and further preferably 35% by mass or more. The proportion of the polyester resin (1) in the binder resin is more preferably 75 mass % or less. The polyester resin (1) will be described in detail later.

[0032] The proportion of the binder resin in the outermost layer of the photoreceptor is preferably 50% by mass or more, and more preferably 55% by mass or more, from the viewpoint of reducing wear variation. The proportion of the binder resin in the outermost layer of the photoreceptor is preferably 70% by mass or less, and more preferably 65% ​​by mass or less, from the viewpoint of electrical properties.

[0033] The binder resin of the outermost layer of the photoreceptor preferably contains two or more resins. By mixing two or more resins, minute irregularities are formed on the outer peripheral surface, and the dynamic friction coefficient of the outer peripheral surface can be reduced.

[0034] From the viewpoint of abrasion resistance of the outermost layer, the binder resin of the outermost layer of the photoreceptor preferably contains a polyester resin and a polycarbonate resin, more preferably contains a polyarylate resin and a polycarbonate resin, and further preferably contains a polyester resin (1) and a polycarbonate resin. 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 preferable.

[0035] When the outermost layer of the photoreceptor contains a polyester resin and a polycarbonate resin, the mass ratio of the two resins, polyester resin:polycarbonate resin, is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, further preferably 30:70 to 75:25, and further preferably 35:65 to 75:25. When the outermost layer of the photoreceptor contains polyester resin (1) and polycarbonate resin, the mass ratio of the two resins, polyester resin (1):polycarbonate resin, is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, even more preferably 30:70 to 75:25, and still more preferably 35:65 to 75:25.

[0036] In the photoreceptor according to this embodiment, the proportion of fluororesin particles in the outermost layer is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass (i.e., no fluororesin particles are contained). Conventionally, it is known that the outermost layer contains fluororesin particles in order to suppress the wear of the photoreceptor. However, if the outermost layer contains fluororesin particles, the exposure light (e.g., laser beam) that forms an electrostatic latent image on the photoreceptor may be scattered, and the reproducibility of fine lines may be reduced. Therefore, it is preferable that the outermost layer of the photoreceptor according to this embodiment does not contain fluororesin particles.

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

[0038] [Polyester resin (1)] The polyester resin, which is the binder resin of the outermost layer, is preferably a polyester resin (1) having at least a dicarboxylic acid unit (A) and a diol unit (B). The polyester resin (1) may contain a dicarboxylic acid unit other than the dicarboxylic acid unit (A). The polyester resin (1) may contain a diol unit other than the diol unit (B).

[0039] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0040] [ka]

[0041] In formula (A), Ar A1 and Ar A2 each independently represents an aromatic ring which may have a substituent; L A is a single bond or a divalent linking group, n A1 is 0, 1 or 2.

[0042] Ar A1 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.

[0043] Ar A1The 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. A1 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.

[0044] Ar A2 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.

[0045] Ar A2 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. A2 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.

[0046] L A When is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Ra 1 )(Ra 2 )-, where Ra 1 and Ra 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; 1 and Ra 2 may be bonded to form a cyclic alkyl group.

[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] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the dicarboxylic acid unit (A1) represented by the following formula (A1), the dicarboxylic acid unit (A2) represented by the following formula (A2), the dicarboxylic acid unit (A3) represented by the following formula (A3), and the dicarboxylic acid unit (A4) represented by the following formula (A4). The dicarboxylic acid unit (A) more preferably contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4), and further preferably contains the dicarboxylic acid unit (A2).

[0051] [ka]

[0052] 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 101is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0053] [ka]

[0054] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra 202 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 201 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 202 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0055] [ka]

[0056] 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.

[0057] [ka]

[0058] 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.

[0059] Ra in formula (A1) 101 , Ra in formula (A2) 201 and Ra 202 , Ra in formula (A3) 301 and Ra 302 And Ra of formula (A4) 401 Since the specific and preferred embodiments of are the same, hereinafter, Ra 101 , Ra 201 , Ra 202 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] [ka]

[0065] Specific examples of the dicarboxylic acid unit (A2) include the following dicarboxylic acid units (A2-1) to (A2-3), but the dicarboxylic acid unit (A2) is not limited thereto.

[0066] [ka]

[0067] 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.

[0068] [ka]

[0069] 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.

[0070] [ka]

[0071] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the above specific examples (A1-1), (A1-7), (A2-3), (A3-2) and (A4-3), more preferably contains at least one selected from the group consisting of (A2-3), (A3-2) and (A4-3), and even more preferably contains at least (A2-3).

[0072] The total mass proportion of the dicarboxylic acid units (A1) to (A4) in the polyester resin (1) is preferably 15 mass % or more and 60 mass % or less. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 15 mass% or more, the outermost layer has good abrasion resistance. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 20 mass% or more, and further preferably 25 mass% or more. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 60 mass% or less, peeling of the outermost surface layer can be suppressed. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 55 mass% or less, and further preferably 50 mass% or less. The dicarboxylic acid units (A1) to (A4) contained in the polyester resin (1) may be of one type or of two or more types.

[0073] Examples of the dicarboxylic acid units (A) other than the dicarboxylic acid units (A1) to (A4) include aliphatic dicarboxylic acid (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid) units, alicyclic dicarboxylic acid (e.g., cyclohexanedicarboxylic acid) units, and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The dicarboxylic acid units contained in the polyester resin (1) may be of one type or two or more types.

[0074] The dicarboxylic acid unit (A) contained in the polyester resin (1) may be of one type or of two or more types.

[0075] The diol unit (B) is a structural unit represented by the following formula (B).

[0076] [ka]

[0077] In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent; L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 is 0, 1 or 2. Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0078] Ar B1 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.

[0079] Ar B1 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0080] Ar B2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0081] Ar B2 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0082] Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, more preferably 1 to 14 carbon atoms, and even more preferably 1 to 10 carbon atoms.

[0083] 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.

[0084] 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.

[0085] The diol unit (B) preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8).

[0086] It is more preferable that the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), and a diol unit (B6) represented by the following formula (B6): It is more preferable that the diol unit (B1) represented by the following formula (B1), the diol unit (B2) represented by the following formula (B2), the diol unit (B5) represented by the following formula (B5), and the diol unit (B6) represented by the following formula (B6) are contained in the diol unit (B1), It is even more preferable that the diol unit (B1) represented by the following formula (B1), the diol unit (B2) represented by the following formula (B2), and the diol unit (B6) represented by the following formula (B6) are contained in the diol unit (B1), It is most preferable that the diol unit (B1) contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1) and a diol unit (B2) represented by the following formula (B2).

[0087] [ka]

[0088] 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 , Rb801 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.

[0089] 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.

[0090] [ka]

[0091] 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.

[0092] 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. 102Specific 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.

[0093] [ka]

[0094] 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.

[0095] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 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 213Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0096] [ka]

[0097] 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.

[0098] 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.

[0099] [ka]

[0100] 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.

[0101] Ar 105The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathylmethyl group, and a phenyl-cyclopentylmethyl group.

[0102] [ka]

[0103] 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.

[0104] 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.

[0105] [ka]

[0106] In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0107] [ka]

[0108] 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.

[0109] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205Since 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 referred to as ".

[0110] 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.

[0111] Rb in formula (B1) 401 , Rb in formula (B2) 402 , Rb in formula (B3) 403 , Rb in formula (B4) 404 , Rb in formula (B5) 405 , Rb in formula (B6) 406 , Rb in formula (B7) 407 and Rb of formula (B8) 408 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 "Rb 400 " is collectively referred to as ".

[0112] 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.

[0113] 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.

[0114] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0115] Rb in formula (B1) 501 , Rb in formula (B2) 502 , Rb in formula (B3) 503 , Rb in formula (B4) 504 , Rb in formula (B5) 505 , Rb in formula (B6) 506 , Rb in formula (B7) 507 and Rb of formula (B8) 508 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb508 "Rb 500 " is collectively referred to as ".

[0116] 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.

[0117] 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.

[0118] Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0119] Rb in formula (B1) 801 , Rb in formula (B2) 802 , Rb in formula (B3) 803 , Rb in formula (B4) 804 , Rb in formula (B5) 805 , Rb in formula (B6) 806 , Rb in formula (B7) 807 and Rb of formula (B8) 808 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 "Rb 800 " is collectively referred to as ".

[0120] 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.

[0121] 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.

[0122] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0123] Rb in formula (B1) 901 , Rb in formula (B2) 902 , Rb in formula (B3) 903 , Rb in formula (B4) 904 , Rb in formula (B5) 905 , Rb in formula (B6) 906 , Rb in formula (B7) 907 and Rb of formula (B8) 908 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb 907 and Rb 908 "Rb 900 " is collectively referred to as ".

[0124] 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.

[0125] 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.

[0126] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0127] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0128] [ka]

[0129] 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.

[0130] [ka]

[0131] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0132] [ka]

[0133] 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.

[0134] [ka]

[0135] 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.

[0136] [ka]

[0137] 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.

[0138] [ka]

[0139] Specific examples of the diol unit (B7) include diol units (B7-1) to (B7-3), but the diol unit (B7) is not limited thereto.

[0140] [ka]

[0141] 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.

[0142] [ka]

[0143] The diol unit (B) contained in the polyester resin (1) may be of one type or of two or more types.

[0144] The mass proportion of the diol unit (B) in the polyester resin (1) is preferably 25 mass % or more and 80 mass % or less. When the mass proportion of the diol unit (B) is 25 mass% or more, peeling of the outermost surface layer can be suppressed. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 30 mass% or more, and further preferably 35 mass% or more. When the mass proportion of the diol unit (B) is 80 mass% or less, the solubility in the coating liquid for forming the outermost layer can be maintained and the abrasion resistance can be improved. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 75 mass% or less, and further preferably 70 mass% or less.

[0145] Examples of the diol units other than the diol units (B) include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0146] 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.

[0147] 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.

[0148] The polyester resin (1) can be obtained by polycondensing a monomer that gives a dicarboxylic acid unit (A) and a monomer that gives a diol unit (B) with other monomers as required by a conventional method. Examples of the method for polycondensing a monomer include an interfacial polymerization method, a solution polymerization method, and a melt polymerization method. The interfacial polymerization method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent that is not compatible with water with a dihydric alcohol dissolved in an alkaline aqueous solution. Examples of literature related to the interfacial polymerization method include WME ARECSON, J. Poly. Sci., XL399, 1959, and JP-B-1959. The interfacial polymerization method has a faster reaction rate than the solution polymerization method, and therefore can suppress hydrolysis of the dicarboxylic acid halide, resulting in a polyester resin with a high molecular weight.

[0149] [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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0158] 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.

[0159] 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).

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0182] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] The thickness of the undercoat layer is preferably set to 15 μm or more, and more preferably within the range of 20 μm to 50 μm.

[0189] [Middle 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.

[0190] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0191] 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.

[0192] The thickness of the intermediate layer is preferably set in the range of 0.1 μm to 3 μm. The intermediate layer may be used as an undercoat layer.

[0193] [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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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 the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensation product of bisphenols and aromatic dicarboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, etc. Here, "insulating" means a material having a volume resistivity of 10 13These binder resins are used alone or in combination of two or more.

[0200] 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.

[0201] The charge generating layer may contain other known additives.

[0202] 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.

[0203] 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.

[0204] As a method for dispersing particles (e.g., charge generating material) in the coating liquid for forming a charge generating layer, for example, a media dispersing machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, or a horizontal sand mill, or a media-less dispersing machine such as an agitator, an ultrasonic dispersing machine, a roll mill, or a high-pressure homogenizer, may be used. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating a fine flow path under high pressure. During dispersion, it is effective to set the average particle size of the charge generating material in the coating liquid for forming a charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0205] 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.

[0206] The thickness of the charge generating layer is preferably set within the range of 0.1 μm or more and 5.0 μm or less, and more preferably 0.2 μm or more and 2.0 μm or less.

[0207] [Charge transport layer] The charge transport layer is, for example, a layer containing a binder resin and a charge transport material, and may be a layer containing a polymer charge transport material.

[0208] 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.

[0209] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

[0210] [ka]

[0211] In structural formula (a-1), Ar T1 , Ar T2 , and ArT3 each independently represents a substituted or unsubstituted aryl group; 6 H 4 -C(R T4 )=C(R T5 )(R T6 ), or -C 6 H 4 -CH=CH-CH=C(R T7 )(R T8 ) is shown. T4 , R T5 , R T6 , R T7 , and R T8 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0212] [ka]

[0213] In structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 each independently represents a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, an amino group substituted with an alkyl group having from 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) and R T12 , R T13 , R T14 , R T15 and R T16each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0214] Among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, 6 H 4 -CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 ) is preferable from the viewpoint of charge mobility.

[0215] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0216] Examples of the binder resin used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, polysilane, etc. Among these, polycarbonate resin or polyarylate resin is suitable as the binder resin. These binder resins are used alone or in combination of two or more. The compounding ratio of the charge transport material to the binder resin is preferably from 10:1 to 1:5 by mass.

[0217] The charge transport layer may contain other known additives.

[0218] 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 solution for forming the charge transport layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary.

[0219] 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.

[0220] 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.

[0221] The thickness of the charge transport layer is set, for example, preferably in the range of 5 μm or more and 50 μm or less, and more preferably in the range of 10 μm or more and 30 μm or less.

[0222] [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. For this reason, 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).

[0223] 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).

[0224] The reactive group of the reactive group-containing charge transport material may be a chain polymerizable group, an epoxy group, -OH, -OR (wherein R is an alkyl group), -NH 2 , -SH, -COOH, -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.

[0225] 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 styryl group (vinyl phenyl 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 styryl group (vinyl phenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof, because of its excellent reactivity.

[0226] 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.

[0227] 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.

[0228] The protective layer may contain other known additives.

[0229] 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.

[0230] 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.

[0231] 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.

[0232] 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.

[0233] [Single-layer photosensitive layer] The single-layer type photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material, a charge transport material, and, if necessary, a binder resin and other known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass to 10% by mass, more preferably 0.8% by mass to 5% by mass, based on the total solid content. The content of the charge transport material in the single-layer photosensitive layer is preferably 5% by mass to 50% by mass, based on the total solid content. The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer. The thickness of the single-layer photosensitive layer is, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 40 μm or less.

[0234] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging device for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, a transfer device for transferring the toner image to the surface of a recording medium, and a cleaning device for cleaning the surface of the electrophotographic photoreceptor.The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

[0235] In the image forming apparatus according to the present embodiment, the charging device has a charging member that directly contacts the photoconductor, and applies a voltage in which an AC voltage is superimposed on a DC voltage to the charging member. When this charging device is used, the fine line reproducibility and abrasion resistance caused by the surface properties of the photoconductor tend to become apparent, and the effect of the photoconductor according to the present embodiment (excellent fine line reproducibility and abrasion resistance) is prominently exhibited.

[0236] In the image forming apparatus according to the present embodiment, the cleaning device cleans the surface of the photoconductor after the toner image is transferred and before charging. The cleaning device includes a cleaning member that contacts the outer peripheral surface of the photoconductor. The cleaning member contacts the outer peripheral surface of the photoconductor, and the photoconductor according to the present embodiment has excellent wear resistance.

[0237] 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 that fixes a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type that directly transfers a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type that primarily transfers a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member, and then secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus provided with a static elimination device that irradiates the surface of an electrophotographic photosensitive member with static elimination light to eliminate static electricity after the transfer of the toner image and before charging; 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.

[0238] 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.

[0239] 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).

[0240] 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.

[0241] 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.

[0242] 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.

[0243] 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.

[0244] 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.

[0245] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0246] -Charging device- As the charging device 8, for example, a contact-type charging member using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. is used. The charging device 8 is a charging device of a type that applies a voltage in which an AC voltage is superimposed on a DC voltage to the contact-type charging member.

[0247] -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.

[0248] -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.

[0249] 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.

[0250] -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.

[0251] -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.

[0252] -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.

[0253] 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

[0254] 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.).

[0255] <Synthesis of polyester resin (1)> Polyester resin (1-1) was synthesized, which is polyester resin (1). In the synthesis of the resin, polymerization was carried out in the presence of a terminal blocking agent, 4-tert-butylphenol, to block the terminals of the polyester resin. Table 1 shows the units and composition of the polyester resin (1-1). A2-3 in Table 1 is a specific example of the above-mentioned dicarboxylic acid unit (A). B1-4 in Table 1 are specific examples of the diol unit (B) described above.

[0256] [Table 1]

[0257] <Example 1> As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm was prepared.

[0258] [Formation of undercoat layer] Zinc oxide (average particle size 70 nm, specific surface area 15 m2 100 parts of a silane coupling agent (trade name: KBM603, Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0259] 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. Next, 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.

[0260] 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, Sumitomo Bayer Urethane Co., Ltd.), and 15 parts of butyral resin (product name: S-LEC BM-1, Sekisui Chemical Co., Ltd.) dissolved in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone, and 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, Momentive Performance Materials Co., Ltd.) were added to the dispersion to obtain a coating liquid for forming an undercoat layer. The coating liquid for forming an undercoat layer was applied to the outer peripheral surface of a conductive substrate by dip coating, and dried and cured at 170°C for 40 minutes to form an undercoat layer with a thickness of 20 μm.

[0261] [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 (product 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 a layer thickness of 0.25 μm.

[0262] [Formation of charge transport layer] Binder resin: polyester resin (1-1) 60 parts ·Charge transport material: CTM-1 ··· 40 parts Solvent: Tetrahydrofuran 270 parts Solvent: toluene 30 parts The above materials were mixed by stirring to obtain a coating solution for forming a charge transport layer, which was then dip-coated onto the charge generating layer and dried at 145° C. for 30 minutes to form a charge transport layer having a thickness of 30 μm.

[0263] [ka]

[0264] <Examples 2 to 14, Comparative Example 1> Each photoreceptor was prepared in the same manner as in Example 1, except that in forming the charge transport layer, part or all of the polyester resin (1-1) was replaced with polycarbonate resin (PC1) and / or the proportion of the binder resin was changed as shown in Table 2.

[0265] [ka]

[0266] <Comparative Example 2> The same procedure as in Example 1 was followed, except that in forming the charge transport layer, the polyester resin (1-1) was replaced with polycarbonate resin (PC1), and PTFE particles (polytetrafluoroethylene particles) with an average particle size of 3.3 μm were used. The mixing ratio of the two components was polycarbonate resin (PC1):PTFE particles=90:10, and the value shown in "Proportion of binder resin in the outermost layer" in Table 2 is the total mass ratio of the polycarbonate resin (PC1) and the PTFE particles.

[0267] <Photoreceptor performance evaluation> The photoconductor of each Example or Comparative Example was mounted on an electrophotographic image forming apparatus Apeos C7070 (FUJIFILM Business Innovation Co., Ltd.) The charging device of this image forming apparatus includes a contact-type charging roll, and applies a voltage in which an AC voltage is superimposed on a DC voltage to the contact-type charging roll.

[0268] [Fine line reproducibility] In an environment with a temperature of 25°C and a relative humidity of 55%, an "ITE High Definition In Megacycle Chart" (Dai Nippon Printing Co., Ltd.) was printed in black on A3-sized plain paper. The fine lines were visually inspected and classified as follows: G1: All fine lines are well reproduced. G2: Very thin lines are partially blurred and / or thickened. Practical use is not affected. G3: There are some parts where very thin wires are connected. Acceptable for practical use. G4: There are parts where very thin wires are connected to each other and parts where very thin wires are connected to each other. Not suitable for practical use.

[0269] [Cleaning ability] Under an environment of 25°C temperature and 55% relative humidity, 40,000 full-page halftone images with a cyan density of 30% were continuously printed on A3-size plain paper. The outer surface of the photoconductor was observed under an optical microscope and classified as follows. The results are shown in Table 2. A: No stains are observed. B: There is very little dirt that does not cause image defects. C: There is a level of dirt that causes image defects.

[0270] [Wear rate of the outermost layer (charge transport layer)] Before and after the above image formation for the evaluation of cleaning performance, the thickness of the charge transport layer was measured at four locations at 90° intervals in the circumferential direction at the center of the axial direction of the photoreceptor. An electromagnetic film thickness meter (Fisher Instruments, Permascope) was used for the measurements. The layer thicknesses at the four locations were averaged, and the average value after image formation was subtracted from the average value before image formation to calculate the amount of wear. The wear rate (nm / kcy) was calculated by dividing the amount of wear by the number of photoreceptor running cycles. The results are shown in Table 2.

[0271] [Table 2]

[0272] 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.

[0273] (((1))) A conductive substrate and a photosensitive layer disposed on the conductive substrate, The outermost layer contains a charge transport material and a binder resin, and the breaking energy is 10 mJ / mm 3 These are the layers above. The dynamic friction coefficient of the outer circumferential surface is 0.5 or more and 1.0 or less. Electrophotographic photoreceptor. (((2))) The coefficient of dynamic friction is expressed as the breaking energy (mJ / mm 3 ) is 0.05 or more and 0.10 or less. (((3))) The electrophotographic photoreceptor according to (((1))) or (((2))), wherein the binder resin contains a polyester resin, and the proportion of the polyester resin in the binder resin is 35% by mass or more and 75% by mass or less. (((4))) The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein the binder resin accounts for 50% by mass or more of the outermost layer. (((5))) The electrophotographic photoreceptor according to any one of (((1))) to (((4))), wherein the proportion of the binder resin in the outermost layer is 55% by mass or more and 70% by mass or less. (((6))) The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein the binder resin contains two or more types of resins. (((7))) The electrophotographic photoreceptor according to (((6))), wherein the two or more resins include a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). (((8))) The electrophotographic photoreceptor according to (((7))), wherein the dicarboxylic acid unit (A) represented by the formula (A) comprises at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3), and a dicarboxylic acid unit (A4) represented by the formula (A4). (((9))) The electrophotographic photoreceptor according to (((7))) or (((8))), wherein the diol unit (B) represented by formula (B) comprises at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8). (((10))) The electrophotographic photoreceptor according to any one of (((6))) to (((9))), wherein the two or more types of resins include a polycarbonate resin. (((11))) The electrophotographic photoreceptor according to any one of (((1))) to (((10))), wherein the photosensitive layer has a charge generating layer and a charge transporting layer, and the charge transporting layer is the outermost layer. (((12))) An electrophotographic photoreceptor according to any one of (((1))) to (((11))); a charging device for charging a surface of the electrophotographic photosensitive member, the charging device having a charging member in direct contact with the electrophotographic photosensitive member and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; A process cartridge that is detachably attached to an image forming apparatus. (((13))) An electrophotographic photoreceptor according to any one of (((1))) to (((11))); a charging device for charging a surface of the electrophotographic photoreceptor, the charging device having a charging member that is in direct contact with the electrophotographic photoreceptor and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; 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; A cleaning device that cleans the surface of the electrophotographic photoreceptor. Image forming device.

[0274] According to (((1))) or (((11))), the fracture energy of the outermost layer is 10 mJ / mm 3 In comparison with a case in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0, an electrophotographic photoreceptor excellent in thin-line reproducibility and abrasion resistance is provided. According to (((2))), an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, as compared with a case in which the value obtained by dividing the dynamic friction coefficient by the breaking energy is less than 0.05 or exceeds 0.10. According to (((3))), an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, compared with a case in which the proportion of the polyester resin in the binder resin is less than 35 mass % or more than 75 mass %. According to (((4))), an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, compared with a case in which the proportion of the binder resin in the outermost layer is less than 50% by mass. According to (((5))), an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, compared with a case in which the proportion of the binder resin in the outermost layer is less than 55% by mass or more than 70% by mass. According to (((6)), (((7)), (((8)), (((9))) or (((10)), an electrophotographic photoreceptor excellent in fine line reproducibility and abrasion resistance is provided, compared to a case where the binder resin is one type of resin. According to (((12))), the breaking energy of the outermost layer of an electrophotographic photoreceptor is 10 mJ / mm 3 The present invention provides a process cartridge having an electrophotographic photosensitive member which is excellent in thin-line reproducibility and wear resistance compared to a case in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0. According to (((13))), the breaking energy of the outermost layer of an electrophotographic photoreceptor is 10 mJ / mm 3 The present invention provides an image forming apparatus equipped with an electrophotographic photoreceptor which is excellent in fine line reproducibility and wear resistance compared to an electrophotographic photoreceptor in which the dynamic friction coefficient of the outer peripheral surface is less than 0.5 or exceeds 1.0. [Explanation of symbols]

[0275] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0276] 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 photosensitive layer disposed on the conductive substrate, The outermost layer contains a charge transport material and a binder resin, and the breaking energy is 10 mJ / mm ３ These are the layers above. The dynamic friction coefficient of the outer peripheral surface is 0.5 or more and 1.0 or less. Electrophotographic photoreceptor.

2. The dynamic friction coefficient is calculated by dividing the breaking energy (mJ / mm ３ 2. The electrophotographic photoreceptor according to claim 1, wherein the value obtained by dividing the average particle diameter by the average particle diameter is 0.05 or more and 0.10 or less.

3. 2. The electrophotographic photoreceptor according to claim 1, wherein the binder resin contains a polyester resin, and the proportion of the polyester resin in the binder resin is 35% by mass or more and 75% by mass or less.

4. The electrophotographic photoreceptor according to claim 1 , wherein the binder resin accounts for 50% by mass or more of the outermost layer.

5. The electrophotographic photoreceptor according to claim 4 , wherein the binder resin accounts for 55% by mass or more and 70% by mass or less of the outermost layer.

6. The electrophotographic photoreceptor according to claim 1 , wherein the binder resin comprises two or more types of resin.

7. The electrophotographic photoreceptor according to claim 6 , wherein the two or more resins include a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B): 【Chemistry 1】 In formula (A), Ar Ａ１ and Ar Ａ２ each independently represents an aromatic ring which may have a substituent; L Ａ is a single bond or a divalent linking group, n Ａ１ is 0, 1 or 2. In formula (B), Ar Ｂ１ and Ar Ｂ２ each independently represents an aromatic ring which may have a substituent; L Ｂ is a single bond, an oxygen atom, a sulfur atom or -C(Rb １ )(Rb ２ )-, n Ｂ１ is 0, 1 or 2. １ and Rb ２ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb １ and Rb ２ may be bonded to form a cyclic alkyl group.

8. 8. The electrophotographic photoreceptor according to claim 7, wherein the dicarboxylic acid unit (A) represented by formula (A) comprises at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). 【Chemistry 2】 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 (A2), n ２０１ and n ２０２ are each independently an integer of 0 to 4, ２０１ Ra ２０１ and n ２０２ Ra ２０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A3), n ３０１ and n ３０２ are each independently an integer of 0 to 4, ３０１ Ra ３０１ and n ３０２ Ra ３０２ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (A4), n ４０１ is an integer of 0 to 6, ４０１ Ra ４０１ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

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

10. The electrophotographic photoreceptor according to claim 7 , wherein the two or more resins include a polycarbonate resin.

11. 2. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a charge generating layer and a charge transporting layer, and the charge transporting layer is the outermost layer.

12. The electrophotographic photoreceptor according to any one of claims 1 to 11, a charging device for charging a surface of the electrophotographic photosensitive member, the charging device having a charging member in direct contact with the electrophotographic photosensitive member and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; A process cartridge that is detachably attached to an image forming apparatus.

13. The electrophotographic photoreceptor according to any one of claims 1 to 11, a charging device for charging a surface of the electrophotographic photoreceptor, the charging device having a charging member that is in direct contact with the electrophotographic photoreceptor and applying a voltage in which an AC voltage is superimposed on a DC voltage to the charging member; 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; A cleaning device that cleans the surface of the electrophotographic photoreceptor. Image forming device.

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