Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

An electrophotographic photoreceptor, a process cartridge, and an image forming apparatus, the electrophotographic photoreceptor including a conductive substrate and a photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, the average thickness of the charge transport layer being 30 [mu] m or more, the charge transport layer containing a polyarylate resin, and the average thickness of the charge transport layer being 30 [mu] m or more. The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1) and formula (2). Formula (1): Iu < = 0.95 * Im, Formula (2): 1.05 * Im < = Il.

Description

Technical Field

[0001] The present invention relates to an electronic photographic photosensitive body, a processing box and an image forming device. Background Art

[0002] Patent document 1 discloses an electronic photographic photosensitive body comprising a support, an undercoat layer, a charge generating layer and a charge transport layer, wherein the charge generating layer contains at least one of an oxytitanium phthalocyanine pigment and a gallium phthalocyanine pigment, and the charge transport layer contains at least one of a polycarbonate resin and a polyarylate resin, and wherein the charge generating layer has an area α in a non-image forming area where the thickness of the charge generating layer is thinner than that of the charge generating layer in an image forming area.

[0003] Patent document 2 discloses an electronic photographic photosensitive body, which has a cylindrical support body, a charge generating layer and a charge transport layer. With respect to the charge generating layer, an area from the central position of the image forming area to the edge position of the image forming area in the axial direction of the cylindrical support body is equally divided into five parts. When the average value of the film thickness of the charge generating layer in each equally divided area is set to d11, d12, d13, d14, and d15 in sequence from the central position of the image forming area toward the edge position of the image forming area, the film thickness of the charge generating layer satisfies the relationship of d11<d12<d13<d14<d15. With respect to the charge transport layer, an area from the central position of the image forming area to the edge position of the image forming area in the axial direction of the cylindrical support body is equally divided into five parts. When the average value of the film thickness of the charge transport layer in each equally divided area is set to d21, d22, d23, d24, and d25 in sequence from the central position of the image forming area toward the edge position of the image forming area, the film thickness of the charge transport layer satisfies the relationship of d21>d22>d23>d24>d25.

[0004] Patent document 3 discloses a method for forming a charge generating layer on a photoconductive drum, the method comprising the following steps: preparing a dispersion having a charge generating composition; immersing an elongated supporting element in the dispersion; extracting a first portion of the elongated supporting element from the dispersion at a first speed, and coating the charge generating composition on the first portion with a first thickness; extracting a second portion of the elongated supporting element from the dispersion at a second speed faster than the first speed, and coating the charge generating composition on the second portion with a second thickness thicker than the first thickness.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-031517

[0006] Patent Document 2: Japanese Patent Application Publication No. 2021-004948

[0007] Patent Document 3: U.S. Patent Application Publication No. 2021 / 0124277 Summary of the invention

[0008] An object of the present invention is to provide an electrophotographic photoreceptor which has excellent wear resistance and is less likely to cause charging unevenness than an electrophotographic photoreceptor which does not satisfy one or both of the formula (1) and the formula (2).

[0009] Specific means for solving the above-mentioned problems include the following aspects: Each formula representing a compound is the same as the formula having the same number described below.

[0010] <1> An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer having a charge generating layer and a charge transporting layer disposed on the conductive substrate, wherein:

[0011] The average thickness of the charge transport layer is 30 μm or more.

[0012] The charge transport layer contains a polyarylate resin,

[0013] The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1) and formula (2):

[0014] Formula (1): Iu≤0.95×Im

[0015] Formula (2): 1.05×Im≤Il

[0016] When the total length of the electrophotographic photoreceptor in the axial direction is defined as L,

[0017] Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor,

[0018] Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end,

[0019] I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

[0020] <2> The electrophotographic photoreceptor according to <1>, wherein

[0021] The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1-3) and formula (2-3),

[0022] Formula (1-3): 0.75×Im<Iu≤0.95×Im

[0023] Formula (2-3): 1.05×Im≤Il<1.25×Im

[0024] When the total length of the electrophotographic photoreceptor in the axial direction is defined as L,

[0025] Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor,

[0026] Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end,

[0027] I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

[0028] <3> The electrophotographic photoreceptor according to <1> or <2>, wherein

[0029] The charge generating layer contains hydroxygallium phthalocyanine.

[0030] <4> The electrophotographic photoreceptor according to any one of <1> to <3>, wherein

[0031] The weight average molecular weight of the polyarylate resin contained in the charge transport layer is 80,000 or more.

[0032] <5> The electrophotographic photoreceptor according to any one of <1> to <4>, wherein

[0033] The charge transport layer further contains a polycarbonate resin.

[0034] <6> The electrophotographic photoreceptor according to any one of <1> to <5>, wherein

[0035] The polyarylate resin includes a polyarylate resin (1) having a dicarboxylic acid unit (A) represented by the formula (A) and a diol unit (B) represented by the formula (B).

[0036] <7> The electrophotographic photoreceptor according to <6>, wherein

[0037] The polyarylate resin (1) has the dicarboxylic acid unit (A) comprising 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).

[0038] <8> The electrophotographic photoreceptor according to <6> or <7>, wherein

[0039] The polyarylate resin (1) comprises at least one diol unit (B) 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).

[0040] <9> The electrophotographic photoreceptor according to any one of <6> to <8>, wherein

[0041] The polyarylate resin (1) has the dicarboxylic acid unit (A) comprising at least one selected from the group consisting of a dicarboxylic acid unit (A2) represented by the formula (A2) and a dicarboxylic acid unit (A4) represented by the formula (A4).

[0042] <10> The electrophotographic photoreceptor according to any one of <6> to <9>, wherein

[0043] The polyarylate resin (1) has the diol unit (B) comprising at least one selected from the group consisting of a diol unit (B1) represented by the formula (B1) and a diol unit (B2) represented by the formula (B2).

[0044] <11> A process cartridge comprising the electrophotographic photoreceptor according to any one of <1> to <10>, wherein

[0045] The process cartridge is attachable to and detachable from the image forming apparatus.

[0046] <12> An image forming apparatus comprising:

[0047] The electrophotographic photoreceptor according to any one of <1> to <10>;

[0048] A charging device for charging the surface of the electrophotographic photoreceptor;

[0049] An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0050] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and

[0051] The transfer device transfers the toner image to the surface of a recording medium.

[0052] Effects of the Invention

[0053] According to the inventions described in <1>, <3>, <5>, <6>, <7>, <8>, <9> or <10>, there is provided an electrophotographic photoreceptor having excellent wear resistance and being less likely to produce uneven charging than an electrophotographic photoreceptor that does not satisfy one or both of formula (1) and formula (2).

[0054] According to the invention of <2>, there is provided an electrophotographic photoreceptor having excellent wear resistance and less prone to uneven charging than an electrophotographic photoreceptor that does not satisfy one or both of the formulas (1-3) and (2-3).

[0055] According to the invention as set forth in <4>, there is provided an electrophotographic photoreceptor having excellent abrasion resistance compared with a case where the weight average molecular weight of the polyarylate resin is less than 80,000.

[0056] According to the invention of <11>, there is provided a process cartridge having an electrophotographic photoreceptor having excellent wear resistance and less prone to uneven charging, compared with a process cartridge including an electrophotographic photoreceptor that does not satisfy one or both of the equations (1) and (2).

[0057] According to the invention of <12>, there is provided an image forming apparatus having an electrophotographic photoreceptor having excellent wear resistance and less prone to uneven charging, compared with an image forming apparatus having an electrophotographic photoreceptor that does not satisfy one or both of the equations (1) and (2). BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0059] Figure 1 is a partial cross-sectional view showing an example of a layer structure of an electrophotographic photoreceptor according to the present embodiment;

[0060] Figure 2 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0061] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0062] Explanation of symbols

[0063] 1-conductive substrate, 2-undercoat layer, 3-charge generating layer, 4-charge transporting layer, 5-photosensitive layer, 10A-photoreceptor.

[0064] 7-electrophotographic photoreceptor, 8-charging device, 9-exposure device, 11-developing device, 13-cleaning device, 14-lubricant, 40-transfer device, 50-intermediate transfer body, 100-image forming device, 120-image forming device, 131-cleaning blade, 132-fibrous component (roller-shaped), 133-fibrous component (flat brush-shaped), 300-processing box. DETAILED DESCRIPTION

[0065] Hereinafter, embodiments of the present invention will be described. These descriptions and examples are intended to illustrate the embodiments and do not limit the scope of the embodiments.

[0066] In the present invention, a numerical range expressed using "to" indicates a range including the numerical values ​​before and after "to" as the minimum value and the maximum value, respectively.

[0067] In the numerical ranges recorded in stages in the present invention, the upper limit or lower limit recorded in one numerical range may also be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical ranges recorded in the present invention, the upper limit or lower limit of the numerical range may also be replaced by the value shown in the embodiment.

[0068] In the present invention, the word "process" is included in this term if the purpose of the process can be achieved not only in an independent process but also in a case where the process cannot be clearly distinguished from other processes.

[0069] In the present invention, when the embodiments are described with reference to the drawings, the structure of the embodiments is not limited to the structure shown in the drawings. In addition, the sizes of the components in the drawings are conceptual, and the relative relationship between the sizes of the components is not limited thereto.

[0070] In the present invention, each component may also include a plurality of corresponding substances. In the present invention, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it indicates the total amount of the plurality of substances present in the composition.

[0071] In the present invention, multiple types of particles corresponding to each component may be contained. When multiple types of particles corresponding to each component are present in the composition, unless otherwise specified, the particle size of each component represents a value for a mixture of the multiple types of particles present in the composition.

[0072] In the present invention, unless otherwise specified, an alkyl group and an alkylene group include linear, branched, and cyclic groups.

[0073] In the present invention, regarding the organic group, aromatic ring, linking group, alkyl group, alkylene group, aryl group, aralkyl group, alkoxy group, aryloxy group and the like, the hydrogen atom in the group may be substituted by a halogen atom.

[0074] In the present invention, when a compound is represented by a structural formula, the structural formula may be represented by omitting the symbols (C and H) representing the carbon atoms and hydrogen atoms in the hydrocarbon group and / or hydrocarbon chain.

[0075] In the present invention, the "structural unit" of the copolymer or resin has the same meaning as the monomer unit.

[0076] In the present invention, the “axial direction” of the electrophotographic photoreceptor means the direction in which the rotation axis of the electrophotographic photoreceptor extends, and the “circumferential direction” of the electrophotographic photoreceptor means the rotation direction of the electrophotographic photoreceptor.

[0077] <Electronic Photographic Photoreceptor>

[0078] The electrophotographic photoreceptor (hereinafter also referred to as “photoreceptor”) according to the present embodiment includes a conductive substrate and a photosensitive layer having a charge generating layer and a charge transporting layer disposed on the conductive substrate.

[0079] Figure 1 This is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to the present embodiment. Figure 1 The photoreceptor 10A shown has a structure in which an undercoat layer 2, a charge generating layer 3, and a charge transporting layer 4 are sequentially stacked on a conductive substrate 1, and the charge generating layer 3 and the charge transporting layer 4 constitute a photosensitive layer 5 (a so-called functional separation type photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generating layer 3. The undercoat layer 2 may or may not be provided.

[0080] In the photoreceptor according to this embodiment,

[0081] The average thickness of the charge transport layer is 30 μm or more.

[0082] The charge transport layer contains a polyarylate resin,

[0083] The absorption spectrum measured after the photosensitive layer was peeled off and dissolved in tetrahydrofuran satisfied the following formula (1) and formula (2).

[0084] Formula (1): Iu≤0.95×Im

[0085] Formula (2): 1.05×Im≤Il

[0086] When the total length of the photoreceptor in the axial direction is L,

[0087] Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the photoreceptor,

[0088] Iu is the absorbance at a wavelength of 678 nm for the photosensitive layer peeled off from the position of 0.40 L from the center toward one end in the axial direction of the photoreceptor,

[0089] I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the position of 0.40L from the center in the axial direction of the photoreceptor toward the other end.

[0090] The photoreceptor according to the present embodiment has the above-mentioned structure, and thus has excellent wear resistance and is less likely to cause uneven charging. The mechanism is estimated as follows.

[0091] For example, the photosensitive layer is preferably thick for the purpose of prolonging the life of the photoreceptor, and the charge transport layer is preferably 30 μm or more. In addition, from the perspective of the wear resistance of the photosensitive layer, for example, polyarylate resin is preferably used as the binder resin of the charge transport layer. A large molecular weight of the polyarylate resin is more conducive to wear resistance.

[0092] The photosensitive layer is usually formed by immersing the conductive substrate in a coating solution with the axial direction thereof set as the gravity direction. Polyarylate resin is a resin that tends to become viscous due to its molecular structure (stacking of aromatic rings), and the larger the molecular weight, the more viscous it tends to become. In order to ensure the coating properties of the coating solution, the concentration of the polyarylate resin in the coating solution is set to a relatively low concentration.

[0093] However, the coating liquid with a lower concentration of polyarylate resin tends to flow in the direction of gravity, and takes a long time to dry. Therefore, the charge transport layer formed by dip coating tends to be thin at the top and thick at the bottom, and the thicker the charge transport layer is, the more obvious this tendency is. The uneven thickness of the charge transport layer in the axial direction of the photoreceptor causes the uneven charging of the photoreceptor.

[0094] In order to solve the above-mentioned problems, in the photoreceptor according to the present embodiment, the thickness of the charge generating layer located below the charge transporting layer is made thinner at one end portion and thicker at the other end portion compared to the central portion.

[0095] It is speculated that when a charge transport layer is formed on a charge generating layer by dip coating, if the thin end of the charge generating layer is placed above the gravity direction and the thick end of the charge generating layer is placed below the gravity direction for dip coating, the uniformity of the thickness of the charge transport layer is improved according to the following mechanism.

[0096] It is believed that if the thickness of the upper end of the charge generating layer is thinner than the central part, the dryness of the thin upper end is high, so the coating liquid for forming the charge transport layer is easy to adhere to the upper end, and the flow of the coating liquid from the upper end is suppressed, thereby suppressing the thin filmization of the charge transport layer at the upper end. In addition, it is believed that the coating liquid for forming the charge transport layer is also easy to be retained at the upper end, thereby suppressing the thin filmization of the charge transport layer at the upper end, based on the fact that the thickness of the upper end of the charge generating layer is thinner than the central part. It is believed that if the thickness of the upper end of the charge generating layer is the same as or thicker than the central part, the coating liquid for forming the charge transport layer is easy to flow in the direction of gravity, thereby easily thinning the charge transport layer at the upper end.

[0097] It is believed that if the thickness of the lower end of the charge generating layer is thicker than that of the central part, the dryness of the thick lower end is low, so the coating liquid for forming the charge transport layer is not easy to adhere to the lower end, and the coating liquid flows from the lower end, thereby suppressing the thickening of the charge transport layer at the lower end. In addition, it is believed that the thickening of the charge transport layer at the lower end is also suppressed based on the fact that the thickness of the lower end of the charge generating layer is thicker than that of the central part. It is believed that if the thickness of the lower end of the charge generating layer is the same as that of the central part or thinner than that of the central part, the coating liquid for forming the charge transport layer accumulates thickly at the lower end, thereby easily thickening the charge transport layer at the lower end.

[0098] According to the above mechanism, the thickness of the charge generating layer is thin at one end and thick at the other end, which improves the uniformity of the thickness of the charge transporting layer. As a result, it is believed that charging unevenness is less likely to occur in the photoreceptor.

[0099] However, the charge generation layer is originally a thin layer. The layer thickness of the charge generation layer is usually less than 1 μm and is several μm at most. Therefore, the difference in the layer thickness of the charge generation layer in the axial direction is very small, and it is sometimes difficult to detect the difference in the layer thickness.

[0100] Therefore, the photoreceptor involved in this embodiment uses the absorbance of the wavelength 678nm in the absorption spectrum of the photosensitive layer as an indicator of the thickness of the charge generating layer. As the charge generating material of the charge generating layer, a charge generating material having absorption at a wavelength of 678nm is often used. It can be considered that the higher the absorbance at a wavelength of 678nm, the thicker the charge generating layer, and the lower the absorbance at a wavelength of 678nm, the thinner the charge generating layer. By comparing the absorbance at a wavelength of 678nm in the central part, one end, and the other end of the photoreceptor, the thickness of the charge generating layer can be known.

[0101] The absorption spectrum of the photosensitive layer was measured as follows.

[0102] The photosensitive layer was peeled off and cut out from position (M), position (U) and position (L) in a square of axial direction × circumferential direction = 1 cm × 1 cm.

[0103] The position (M) is the center of the photoreceptor in the axial direction.

[0104] The position (U) is a position 0.40 L from the center of the photoreceptor in the axial direction toward one end. Here, L is the total length of the photoreceptor in the axial direction.

[0105] The position (L) is a position 0.40 L from the center of the photoreceptor in the axial direction toward the other end. Here, L is the total length of the photoreceptor in the axial direction.

[0106] The photosensitive layer was cut out at four positions with 90° scales along the circumference at position (M), position (U), and position (L). Thus, four 1 cm×1 cm square films were obtained at position (M), position (U), and position (L).

[0107] Four films are immersed in 100 mL of tetrahydrofuran for each position to prepare a solution, and the solution is used as a sample, and an absorption spectrum is measured by an ultraviolet-visible spectrophotometer (eg, HITACHI U2000) to detect the absorbance at a wavelength of 678 nm.

[0108] The absorbance of the photosensitive layer at position (M) at a wavelength of 678 nm is referred to as Im.

[0109] The absorbance of the photosensitive layer at position (U) at a wavelength of 678 nm is referred to as Iu.

[0110] The absorbance of the photosensitive layer at position (L) at a wavelength of 678 nm is referred to as I1.

[0111] In the photoreceptor according to the present embodiment, Iu and Im are in the relationship of formula (1): Iu≤0.95×Im.

[0112] If Iu exceeds 0.95×Im, for example, one end of the charge generation layer (the upper end when the charge transport layer is formed by dip coating) is not as thin as desired, so the charge transport layer is easily thinned in this part. From the viewpoint of suppressing the thinning of the charge transport layer in this part, for example, Iu and Im are in the relationship of formula (1), preferably in the relationship of formula (1-1), more preferably in the relationship of formula (1-2), and further preferably in the relationship of formula (1-3).

[0113] Formula (1): Iu≤0.95×Im

[0114] Formula (1-1): 0.70×Im<Iu≤0.95×Im

[0115] Formula (1-2): 0.75×Im≤Iu≤0.95×Im

[0116] Formula (1-3): 0.75×Im<Iu≤0.95×Im

[0117] In the photoreceptor according to the present embodiment, Il and Im are in the relationship of formula (2): 1.05×Im≤Il.

[0118] If Il is less than 1.05×Im, for example, the other end of the charge generation layer (the lower end when the charge transport layer is formed by dip coating) is not as thick as desired, so the charge transport layer is easily thickened in this part. From the viewpoint of suppressing the thickening of the charge transport layer in this part, for example, Il and Im are in the relationship of formula (2), preferably in the relationship of formula (2-1), more preferably in the relationship of formula (2-2), and further preferably in the relationship of formula (2-3).

[0119] Formula (2): 1.05×Im≤Il

[0120] Formula (2-1): 1.05×Im≤Il<1.30×Im

[0121] Formula (2-2): 1.05×Im≤Il≤1.25×Im

[0122] Formula (2-3): 1.05×Im≤Il<1.25×Im

[0123] As a method of making the thickness of the charge generating layer thinner at one end portion and thicker at the other end portion than at the center portion, the following method can be mentioned so as to satisfy the formula (1) and the formula (2).

[0124] When the charge generating layer is formed by dip coating, when the conductive substrate is pulled upward from the charge generating layer forming coating liquid in the direction of gravity, the speed is controlled so that the pulling speed at the upper end is less than the pulling speed at the center and less than the pulling speed at the lower end.

[0125] When the charge generating layer is formed by the blade coating method, the blade pressure on the conductive substrate is controlled so that the blade pressure at one end > the blade pressure at the center > the blade pressure at the other end.

[0126] When the charge generating layer is formed by a spray coating method, the spray amount of the coating liquid is controlled so that the spray amount at one end portion is less than the spray amount at the center portion and less than the spray amount at the other end portion.

[0127] In the above methods, the "central portion" is preferably a region that occupies, for example, 60% to 80% of the total axial length L of the photoreceptor. In the central portion, the pulling speed, blade pressure, or spray amount is preferably constant.

[0128] Hereinafter, the polyarylate resin contained in the charge transport layer and each layer of the photoreceptor will be described in detail.

[0129] [Polyarylate resin (1)]

[0130] The polyarylate resin as the binder resin of the charge transport layer is preferably a polyarylate resin (1) having at least a dicarboxylic acid unit (A) and a diol unit (B). The polyarylate resin (1) may contain other dicarboxylic acid units other than the dicarboxylic acid unit (A). The polyarylate resin (1) may contain other diol units other than the diol unit (B).

[0131] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0132] [Chemical formula 1]

[0133] Formula (A)

[0134] In formula (A), Ar A1 and Ar A2 are each independently 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.

[0135] Ar A1 The aromatic ring may be a monocyclic ring or a polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and preferably a benzene ring and a naphthalene ring.

[0136] Ar A1 The hydrogen atoms on the aromatic ring of may be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. A1 When the aromatic ring is substituted, the substituent is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

[0137] Ar A2 The aromatic ring may be a monocyclic ring or a polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and preferably a benzene ring and a naphthalene ring.

[0138] Ar A2 The hydrogen atoms on the aromatic ring of may be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. A2 When the aromatic ring is substituted, the substituent is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

[0139] When L A When it is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Ra 1)(Ra 2 )-. Here, 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, Ra 1 With Ra 2 They may be bonded to form a cyclic alkyl group.

[0140] 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.

[0141] Ra 1 and Ra 2 The aryl group having 6 or more and 12 or less carbon atoms may be a monocyclic or polycyclic ring. The aryl group preferably has 6 or more and 10 or less carbon atoms, and more preferably 6 carbon atoms.

[0142] Ra 1 and Ra 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms 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.

[0143] Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be a monocyclic or polycyclic ring. The aryl group preferably has 6 to 10 carbon atoms, and more preferably 6 carbon atoms.

[0144] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the following 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).

[0145] For example, the dicarboxylic acid unit (A) more preferably contains at least one selected from the group consisting of dicarboxylic acid units (A2), dicarboxylic acid units (A3) and dicarboxylic acid units (A4), further preferably contains at least one selected from the group consisting of dicarboxylic acid units (A2) and dicarboxylic acid units (A4), and further preferably contains dicarboxylic acid units (A2).

[0146] [Chemical formula 2]

[0147] Formula (A1)

[0148] In formula (A1), n 101 is an integer greater than or equal to 0 and less than or equal to 4, 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.

[0149] n 101 For example, it is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0150] [Chemical formula 3]

[0151] Formula (A2)

[0152] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, and n 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.

[0153] n 201 For example, it is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0154] n 202 For example, it is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0155] [Chemical formula 4]

[0156] Formula (A3)

[0157] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, and n 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.

[0158] n 301 For example, it is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0159] n 302 For example, it is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0160] [Chemical formula 5]

[0161] Formula (A4)

[0162] In formula (A4), n 401 is an integer greater than or equal to 0 and less than or equal to 6, 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.

[0163] n 401 For example, it is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and still more preferably 0.

[0164] Ra of formula (A1) 101 , Ra of formula (A2) 201 and Ra 202 , Ra of formula (A3) 301 and Ra 302 And Ra of formula (A4) 401 The specific method and preferred method are the same, so in the following, Ra 101 , Ra 201 , Ra 202 , Ra 301 , Ra 302 and Ra 401 They are collectively referred to as “Ra” for explanation.

[0165] The alkyl group having 1 to 10 carbon atoms represented by Ra may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0166] Examples of the linear alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl.

[0167] Examples of the branched alkyl group having 3 to 10 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, and tert-decyl.

[0168] Examples of the cyclic alkyl group having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups in which these monocyclic alkyl groups are linked.

[0169] The aryl group having 6 or more and 12 or less carbon atoms represented by Ra may be a monocyclic or polycyclic group. The aryl group preferably has 6 or more and 10 or less carbon atoms, and more preferably 6 carbon atoms.

[0170] Examples of the aryl group having 6 to 12 carbon atoms include phenyl, biphenyl, 1-naphthyl, and 2-naphthyl.

[0171] The alkyl group in the alkoxy group having 1 to 6 carbon atoms represented by Ra may be any of linear, branched, and 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.

[0172] 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.

[0173] Examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy and tert-hexyloxy.

[0174] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy.

[0175] Hereinafter, dicarboxylic acid units (A1-1) to (A1-9) are shown as specific examples of the dicarboxylic acid unit (A1). The dicarboxylic acid unit (A1) is not limited thereto.

[0176] [Chemical formula 6]

[0177]

[0178] Hereinafter, dicarboxylic acid units (A2-1) to (A2-3) are shown as specific examples of the dicarboxylic acid units (A2), but the dicarboxylic acid units (A2) are not limited thereto.

[0179] [Chemical formula 7]

[0180]

[0181] Hereinafter, dicarboxylic acid units (A3-1) to (A3-2) are shown as specific examples of the dicarboxylic acid unit (A3). The dicarboxylic acid unit (A3) is not limited thereto.

[0182] [Chemical formula 8]

[0183]

[0184] Hereinafter, dicarboxylic acid units (A4-1) to (A4-3) are shown as specific examples of the dicarboxylic acid unit (A4). The dicarboxylic acid unit (A4) is not limited thereto.

[0185] [Chemical formula 9]

[0186]

[0187] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of (A1-1), (A1-7), (A2-3), (A3-2) and (A4-3) as the specific examples above, more preferably contains at least one selected from the group consisting of (A2-3), (A3-2) and (A4-3), further preferably contains at least one selected from the group consisting of (A2-3) and (A4-3), and most preferably contains at least (A2-3).

[0188] The total mass ratio of the dicarboxylic acid units (A1) to (A4) in the polyarylate resin (1) is preferably, for example, 15 mass % or more and 60 mass % or less.

[0189] When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 15 mass % or more, the abrasion resistance of the photosensitive layer is good. From this viewpoint, the total mass ratio of the dicarboxylic acid units (A1) to (A4) is, for example, more preferably 20 mass % or more, and further preferably 25 mass % or more.

[0190] When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 60 mass % or less, peeling of the photosensitive layer can be suppressed. From this viewpoint, the total mass ratio of the dicarboxylic acid units (A1) to (A4) is, for example, more preferably 55 mass % or less, and further preferably 50 mass % or less.

[0191] The dicarboxylic acid units (A1) to (A4) contained in the polyarylate resin (1) may be one type or two or more types.

[0192] Examples of other 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, alkenyl succinic acid, adipic acid, sebacic acid) units, alicyclic dicarboxylic acid (e.g., cyclohexane dicarboxylic acid) units, and lower (e.g., carbon number of 1 to 5) alkyl ester units thereof. The dicarboxylic acid units contained in the polyarylate resin (1) may be one type or two or more types.

[0193] The dicarboxylic acid units (A) contained in the polyarylate resin (1) may be one type or two or more types.

[0194] The diol unit (B) is a structural unit represented by the following formula (B).

[0195] [Chemical formula 10]

[0196] Formula (B)

[0197] In formula (B), Ar B1 and Ar B2 are each independently an aromatic ring which may have a substituent, L B is a single bond, oxygen atom, sulfur atom or -C(Rb 1 )(Rb 2 )-,n B1 is 0, 1 or 2. 1 and Rb 2 are each independently 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, and Rb 1 With Rb 2 They may be bonded to form a cyclic alkyl group.

[0198] Ar B1 The aromatic ring may be a monocyclic ring or a polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and preferably a benzene ring and a naphthalene ring.

[0199] Ar B1 The hydrogen atoms on the aromatic ring of may be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. B1 When the aromatic ring is substituted, the substituent is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

[0200] Ar B2The aromatic ring may be a monocyclic ring or a polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and preferably a benzene ring and a naphthalene ring.

[0201] Ar B2 The hydrogen atoms on the aromatic ring of may be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. B2 When the aromatic ring is substituted, the substituent is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms.

[0202] R 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.

[0203] R 1 and Rb 2 The aryl group having 6 or more and 12 or less carbon atoms may be a monocyclic or polycyclic ring. The aryl group preferably has 6 or more and 10 or less carbon atoms, and more preferably 6 carbon atoms.

[0204] R 1 and Rb 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms 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.

[0205] R 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be a monocyclic or polycyclic ring. The aryl group preferably has 6 to 10 carbon atoms, and more preferably 6 carbon atoms.

[0206] The diol unit (B) preferably includes 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).

[0207] For example, the diol unit (B) more preferably includes at least one selected from the group consisting of diol units (B1), diol units (B2), diol units (B4), diol units (B5) and diol units (B6), further preferably includes at least one selected from the group consisting of diol units (B1), diol units (B2), diol units (B5) and diol units (B6), further preferably includes at least one selected from the group consisting of diol units (B1), diol units (B2) and diol units (B6), and most preferably includes at least one selected from the group consisting of diol units (B1) and diol units (B2).

[0208] [Chemical formula 11]

[0209] Formula (B1)

[0210] 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 of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0211] R 101 The branched alkyl group having 4 to 20 carbon atoms preferably has 4 to 16 carbon atoms, more preferably 4 to 12 carbon atoms, and even more preferably 4 to 8 carbon atoms. 101 Specific examples of include isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, isododecyl, sec-dodecyl, tert-dodecyl, tert-tetradecyl, and tert-pentadecyl.

[0212] [Chemical formula 12]

[0213] Formula (B2)

[0214] In formula (B2), Rb 102 is a straight-chain 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 902Each of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0215] R 102 The carbon number of the linear alkyl group having 4 or more and 20 or less is, for example, preferably 4 or more and 16 or less, more preferably 4 or more and 12 or less, and even more preferably 4 or more and 8 or less. 102 Specific examples include n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, tridecyl, n-tetradecyl, n-pentadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl.

[0216] [Chemical formula 13]

[0217] Formula (B3)

[0218] 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 of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0219] R 113 and Rb 213 The carbon number of the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of the group include a methyl group, an ethyl group, and an n-propyl group.

[0220] R 113 and Rb 213 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be any of linear, branched, and 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 further preferably 1. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropyloxy, and cyclobutyloxy.

[0221] As Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0222] [Chemical formula 14]

[0223] Formula (B4)

[0224] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, Rb 404 , Rb 504 , Rb 804 and Rb 904 Each of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0225] R 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, more preferably 1. 104 Specific examples of include methyl, ethyl, n-propyl, isopropyl and cyclopropyl.

[0226] [Chemical formula 15]

[0227] Formula (B5)

[0228] 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 of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0229] Ar 105 The aryl group having 6 or more and 12 or less carbon atoms may be a monocyclic or polycyclic ring. The aryl group preferably has 6 or more and 10 or less carbon atoms, and more preferably 6 carbon atoms.

[0230] Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms 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. 105The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic group. The number of carbon atoms of the aryl group is preferably, for example, 6 to 10, more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthracenylmethyl, and phenyl-cyclopentylmethyl.

[0231] [Chemical formula 16]

[0232] Formula (B6)

[0233] 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 of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0234] R 116 and Rb 216 The carbon number of the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of the group include a methyl group, an ethyl group, and an n-propyl group.

[0235] R 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be any of linear, branched, and 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 further preferably 1. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropyloxy, and cyclobutyloxy.

[0236] As Rb 116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0237] [Chemical formula 17]

[0238] Formula (B7)

[0239] In formula (B7), Rb407 , Rb 507 , Rb 807 and Rb 907 Each of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0240] [Chemical formula 18]

[0241] Formula (B8)

[0242] In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 Each of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0243] Rb in formula (B1) 201 , Rb of formula (B2) 202 , Rb of formula (B4) 204 And Rb in formula (B5) 205 The specific method and preferred method are the same, so below, Rb 201 , Rb 202 , Rb 204 and Rb 205 Collectively referred to as "Rb 200 " to explain.

[0244] R 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably 1 carbon atom.

[0245] 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.

[0246] Rb in formula (B1) 401 , Rb of formula (B2) 402 , Rb of formula (B3) 403 , Rb of formula (B4) 404 , Rb of formula (B5) 405 , Rb of formula (B6) 406 , Rb of formula (B7) 407 And Rb in formula (B8) 408 The specific method and preferred method are the same, so below, Rb 401 , Rb 402 , Rb 403 , Rb 404 , Rb405 , Rb 406 , Rb 407 and Rb 408 Collectively referred to as "Rb 400 " to explain.

[0247] R 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 carbon atom.

[0248] 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.

[0249] Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

[0250] Examples of the cyclic alkyl group having 3 or 4 carbon atoms include cyclopropyl and cyclobutyl.

[0251] R 400 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of linear, branched, and 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.

[0252] 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.

[0253] Examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy and tert-hexyloxy.

[0254] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy.

[0255] As Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0256] Rb in formula (B1) 501 , Rb of formula (B2) 502 , Rb of formula (B3) 503 , Rb of formula (B4) 504 , Rb of formula (B5) 505 , Rb of formula (B6) 506 , Rb of formula (B7)507 And Rb in formula (B8) 508 The specific method and preferred method are the same, so below, Rb 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 Collectively referred to as "Rb 500 " to explain.

[0257] R 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 carbon atom.

[0258] 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.

[0259] Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

[0260] Examples of the cyclic alkyl group having 3 or 4 carbon atoms include cyclopropyl and cyclobutyl.

[0261] R 500 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of linear, branched, and 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.

[0262] 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.

[0263] Examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy and tert-hexyloxy.

[0264] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy.

[0265] As Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0266] Rb in formula (B1) 801, Rb of formula (B2) 802 , Rb of formula (B3) 803 , Rb of formula (B4) 804 , Rb of formula (B5) 805 , Rb of formula (B6) 806 , Rb of formula (B7) 807 And Rb in formula (B8) 808 The specific method and preferred method are the same, so below, Rb 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 Collectively referred to as "Rb 800 " to explain.

[0267] R 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 carbon atom.

[0268] 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.

[0269] Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

[0270] Examples of the cyclic alkyl group having 3 or 4 carbon atoms include cyclopropyl and cyclobutyl.

[0271] R 800 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of linear, branched, and 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.

[0272] 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.

[0273] Examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy and tert-hexyloxy.

[0274] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy.

[0275] As Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0276] Rb in formula (B1) 901 , Rb of formula (B2) 902 , Rb of formula (B3) 903 , Rb of formula (B4) 904 , Rb of formula (B5) 905 , Rb of formula (B6) 906 , Rb of formula (B7) 907 And Rb in formula (B8) 908 The specific method and preferred method are the same, so below, Rb 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb 907 and Rb 908 Collectively referred to as "Rb 900 " to explain.

[0277] R 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 carbon atom.

[0278] 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.

[0279] Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

[0280] Examples of the cyclic alkyl group having 3 or 4 carbon atoms include cyclopropyl and cyclobutyl.

[0281] R 900 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of linear, branched, and 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.

[0282] 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.

[0283] Examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy and tert-hexyloxy.

[0284] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy.

[0285] As Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0286] Hereinafter, diol units (B1-1) to (B1-6) are shown as specific examples of the diol unit (B1), but the diol unit (B1) is not limited thereto.

[0287] [Chemical formula 19]

[0288]

[0289] Hereinafter, diol units (B2-1) to (B2-11) are shown as specific examples of the diol unit (B2), but the diol unit (B2) is not limited thereto.

[0290] [Chemical formula 20]

[0291]

[0292] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0293] [Chemical formula 21]

[0294]

[0295] Specific examples of the diol unit (B4) include diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0296] [Chemical formula 22]

[0297]

[0298] Specific examples of the diol unit (B5) include diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0299] [Chemical formula 23]

[0300]

[0301] Specific examples of the diol unit (B6) include diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0302] [Chemical formula 24]

[0303]

[0304] Hereinafter, diol units (B7-1) to (B7-3) are shown as specific examples of the diol unit (B7), but the diol unit (B7) is not limited thereto.

[0305] [Chemical formula 25]

[0306]

[0307] Specific examples of the diol unit (B8) include diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0308] [Chemical formula 26]

[0309]

[0310] The diol unit (B) contained in the polyarylate resin (1) may be one kind or two or more kinds.

[0311] The mass ratio of the diol unit (B) in the polyarylate resin (1) is preferably, for example, 25 mass % or more and 80 mass % or less.

[0312] When the mass ratio of the diol unit (B) is 25 mass % or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass ratio of the diol unit (B) is, for example, more preferably 30 mass % or more, and further preferably 35 mass % or more.

[0313] When the mass ratio of the diol unit (B) is 80 mass % or less, the solubility in the coating solution for forming the photosensitive layer can be maintained and the wear resistance can be improved. From this viewpoint, the mass ratio of the diol unit (B) is, for example, more preferably 75 mass % or less, and further preferably 70 mass % or less.

[0314] Examples of other diol units other than the diol unit (B) include aliphatic diol (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol) units and alicyclic diol (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A) units. The diol units contained in the polyarylate resin (1) may be one type or two or more types.

[0315] The ends of the polyarylate resin (1) may be capped or modified by an end-capping agent or a molecular weight modifier used in the production. Examples of the end-capping agent or molecular weight modifier include monophenols, monoacid chlorides, monoalcohols, and monocarboxylic acids.

[0316] Examples of the monohydric phenol 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, Phenol, 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, 2-phenyl-2-(3-hydroxyphenyl)propane.

[0317] Examples of the monoacid chloride include monofunctional acid halides such as benzoyl chloride, benzoyl chloride, methanesulfonyl chloride, phenyl chloroformate, acetyl chloride, butyryl chloride, octanoyl chloride, benzenesulfonyl chloride, benzenesulfenyl chloride, sulfenyl chloride, phenylphosphonyl chloride, and substitution products thereof.

[0318] Examples of the monohydric alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol.

[0319] Examples of the monocarboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, methylbenzoic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0320] From the viewpoint of the wear resistance of the charge transport layer, the weight average molecular weight of the polyarylate resin and the polyarylate resin (1) is, for example, preferably 50,000 or more, more preferably 80,000 or more, and even more preferably 100,000 or more.

[0321] From the viewpoint of setting the polyarylate resin concentration of the charge transport layer-forming coating liquid to a certain level or higher, the weight average molecular weight of the polyarylate resin and the polyarylate resin (1) is, for example, preferably 300,000 or less, more preferably 250,000 or less, and even more preferably 200,000 or less.

[0322] The molecular weights of the polyarylate resin and the polyarylate resin (1) are molecular weights in terms of polystyrene measured by GPC (gel permeation chromatography). Tetrahydrofuran is used as an eluent in GPC.

[0323] The polyarylate resin (1) is obtained by polycondensing a monomer imparting a dicarboxylic acid unit (A) and a monomer imparting a diol unit (B), and other monomers as needed, by a conventional method. Examples of the polycondensation method of the monomers include interfacial polymerization, solution polymerization, and melt polymerization. The interfacial polymerization method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent incompatible with water and a diol dissolved in an alkaline aqueous solution. Examples of literature related to the interfacial polymerization method include WMEARECKSON, J.Poly.Sci., XL399, 1959, Special Publication No. 40-1959, and the like. Compared with the solution polymerization method, the interfacial polymerization method has a fast reaction, so the hydrolysis of the dicarboxylic acid halide can be suppressed, and as a result, a high molecular weight polyarylate resin can be obtained.

[0324] [Conductive substrate]

[0325] As the conductive substrate, for example, 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.) can be cited. In addition, as the conductive substrate, for example, conductive compounds (such as conductive polymers, indium oxide, etc.); paper coated, vapor-deposited, or laminated with metals (such as aluminum, palladium, gold, etc.) or alloys; resin films; belts, etc. Here, "conductive" means that the volume resistivity is less than 1×10 13 Ω·cm.

[0326] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to 0.04 μm or more and 0.5 μm or less in terms of center line average roughness Ra for the purpose of suppressing interference fringes generated when irradiating a laser beam. When incoherent light is used as a light source, roughening to prevent interference fringes is not particularly necessary, but the generation of defects caused by the unevenness of the conductive substrate surface is suppressed, so it is suitable for a longer life.

[0327] Examples of the roughening method include wet grinding in which an abrasive is suspended in water and sprayed onto the conductive substrate, centerless grinding in which the conductive substrate is pressed against a rotating grinding wheel and continuously ground, and anodizing.

[0328] As a method of roughening, there is also a method in which, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and roughening is performed by particles dispersed in the layer.

[0329] The roughening treatment based on anodization is to use a metal (e.g., aluminum) conductive substrate as an anode and perform anodization in an electrolyte solution, thereby forming an oxide film on the surface of the conductive substrate. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be cited. However, the porous anodized film formed by anodization has chemical activity in its original state, is easily contaminated, and the resistance change caused by the environment is also large. Therefore, for example, it is preferred that the porous anodized film is blocked by the volume expansion caused by water and reaction in pressurized water vapor or boiling water (metal salts such as nickel can be added) to change the micropores of the oxide film to the sealing treatment of a more stable hydrated oxide.

[0330] The film thickness of the anodized film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, the barrier property against injection tends to function and the increase in residual potential due to repeated use tends to be suppressed.

[0331] The conductive substrate may be subjected to a treatment using an acidic treatment liquid or a boehmite treatment.

[0332] The treatment based on the acidic treatment solution is implemented, for example, in the following manner. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The proportion of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment solution is, for example, in the range of 10 mass % to 11 mass % for phosphoric acid, in the range of 3 mass % to 5 mass % for chromic acid, and in the range of 0.5 mass % to 2 mass % for hydrofluoric acid, and the concentration of the total amount of these acids is preferably in the range of 13.5 mass % to 18 mass %. The treatment temperature is, for example, preferably 42° C. to 48° C. The film thickness of the film is, for example, preferably 0.3 μm to 15 μm.

[0333] The boehmite treatment is carried out, for example, by immersing in pure water at 90°C to 100°C for 5 to 60 minutes or contacting in heated water vapor at 90°C to 120°C for 5 to 60 minutes. The film thickness of the film is preferably 0.1 μm to 5 μm. An anodizing treatment can be further performed using an electrolyte solution with low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0334] [Undercoat]

[0335] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0336] Examples of inorganic particles include powder resistance (volume resistivity) of 1×10 2 Ω·cm or more and 1×10 11 Inorganic particles with a particle size of less than Ω·cm.

[0337] Among them, examples of the inorganic particles having the above 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.

[0338] The specific surface area of ​​the inorganic particles based on the BET method is, for example, 10 m 2 / g or above.

[0339] The volume average particle size of the inorganic particles may be, for example, 50 nm or more and 2000 nm or less (for example, preferably 60 nm or more and 1000 nm or less).

[0340] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less, based on the binder resin.

[0341] The inorganic particles may be subjected to surface treatment. Two or more inorganic particles having different surface treatments or particles having different particle sizes may be used in combination.

[0342] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, for example, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0343] Examples of the silane coupling agent 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.

[0344] Silane coupling agents can be mixed and used in two or more ways. For example, silane coupling agents with amino groups can be used in combination with other silane coupling agents. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, etc. can be cited, but it is not limited thereto.

[0345] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0346] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0347] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier blocking properties, the undercoat layer preferably contains an electron accepting compound (acceptor compound) together with the inorganic particles.

[0348] As electron accepting compounds, for example, there can be mentioned quinone compounds such as chloranil and tetrabromobenzoquinone; tetracyanobenzoquinone dimethane 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-tert-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-tert-butyldiphenoquinone; benzophenone compounds; and other electron transporting substances.

[0349] In particular, the electron accepting compound is preferably a compound having an anthraquinone structure. The compound having an anthraquinone structure is preferably a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, and more specifically, anthraquinone, alizarin, quinizarin, anthraquinone, purpurin, and the like.

[0350] 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 the undercoat layer in a state of being attached to the surfaces of the inorganic particles.

[0351] Examples of a method for attaching the electron accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0352] The dry method is, for example, a method in which an electron accepting compound is directly added dropwise or an electron accepting compound dissolved in an organic solvent is added dropwise while stirring the inorganic particles by a mixer with a large shear force, and the electron accepting compound is sprayed together with dry air or nitrogen to attach the electron accepting compound to the surface of the inorganic particles. When the electron accepting compound is added dropwise or sprayed, it is preferably performed at a temperature below the boiling point of the solvent. After the electron accepting compound is added dropwise or sprayed, sintering can also be performed at a condition of 100°C or above. There is no particular limitation on sintering as long as the temperature and time at which the electrophotographic properties can be obtained.

[0353] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent by stirring, ultrasonic waves, a sand mill, a grinder, a ball mill, etc., and after adding an electron accepting compound and stirring or dispersing, the solvent is removed to attach the electron accepting compound to the surface of the inorganic particles. The solvent removal method is, for example, to remove the solvent by filtering or distilling. After removing the solvent, sintering can also be performed at a condition of 100°C or above. Sintering is not particularly limited as long as the temperature and time are such that electronic photographic properties can be obtained. In the wet method, the water content of the inorganic particles can be removed before adding the electron accepting compound. As examples thereof, a method of removing the water content while stirring and heating in a solvent and a method of removing the water content by azeotropic co-existence with the solvent can be cited.

[0354] The electron accepting compound may be attached before or after the inorganic particles are surface treated with a surface treatment agent, or the electron accepting compound may be attached and the surface treated with a surface treatment agent may be simultaneously performed.

[0355] The content of the electron accepting compound may be, for example, 0.01 mass % to 20 mass % inclusive, and preferably 0.01 mass % to 10 mass % inclusive, based on the inorganic particles.

[0356] Examples of the binder resin used in the lower coating layer include acetal resins (e.g., polyvinyl butyral), 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, epoxy resins and other well-known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; silane coupling agents and other well-known materials.

[0357] Examples of the binder resin used in the undercoat layer include a charge transporting resin having a charge transporting group, and a conductive resin (for example, polyaniline).

[0358] Among them, the binding resin used in the lower coating layer is preferably a resin that is insoluble in the coating solvent in the upper layer, and is particularly preferably a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenolic resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, epoxy resin, polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin with a curing agent.

[0359] When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0360] In order to improve electrical characteristics, improve environmental stability, and improve image quality, various additives may be included in the undercoat layer.

[0361] As additives, there can be mentioned known materials such as polycyclic condensation type, azo type and other electron transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but can also be added to the undercoat layer as an additive.

[0362] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0363] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0364] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octanediol, ammonium lactate titanium, titanium lactate, ethyl lactate titanium, triethanolamine titanium, and polyhydroxystearate titanium.

[0365] Examples of the aluminum chelate compound include aluminum isopropoxide, monobutoxyaluminum diisopropoxide, aluminum butoxide, diethyl acetoacetate aluminum diisopropoxide, and tris(ethyl acetoacetate)aluminum.

[0366] These additives may be used alone or in the form of a mixture or polycondensate of a plurality of compounds.

[0367] The undercoat layer may have a Vickers hardness of 35 or more, for example.

[0368] In order to suppress interference moire images, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to, for example, 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the exposure laser wavelength λ used.

[0369] In order to adjust the surface roughness, resin particles or the like may be added to the undercoat layer. Examples of the resin particles include silicone resin particles and cross-linked polymethacrylate methyl resin particles. In addition, in order to adjust the surface roughness, the surface of the undercoat layer may be ground. Examples of the grinding method include polishing, sandblasting, wet grinding, grinding, and the like.

[0370] The formation of the undercoat layer is not particularly limited and can be performed by a known formation method. For example, the undercoat layer can be formed by forming a coating film of an undercoat layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating as necessary.

[0371] Examples of the solvent used for preparing the coating solution for forming an undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0372] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0373] Examples of a method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0374] Examples of a method for applying the coating liquid for forming an undercoat layer onto the conductive substrate include common methods such as dip coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, and curtain coating.

[0375] The average thickness of the undercoat layer is, for example, preferably 10 μm to 40 μm, more preferably 14 μm to 36 μm, further preferably 18 μm to 32 μm, and further preferably 20 μm to 30 μm.

[0376] [Middle layer]

[0377] An intermediate layer may be provided between the undercoat layer and the photosensitive layer.

[0378] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, melamine resins and other polymer compounds.

[0379] The intermediate layer may be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0380] The compounds used in the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0381] Among them, the intermediate layer is preferably a layer containing an organic metal compound containing zirconium atoms or silicon atoms, for example.

[0382] The formation of the intermediate layer is not particularly limited and can be performed by a known formation method. For example, the intermediate layer can be formed by forming a coating film of an intermediate layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0383] As a coating method for forming the intermediate layer, a common method such as a dip coating method, a push coating method, a wire bar coating method, a spray coating method, a blade coating method, an air knife coating method, a curtain coating method, etc. can be used.

[0384] The thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm or more and 3 μm or less. The intermediate layer can be used as an undercoat layer.

[0385] [Charge Generation Layer]

[0386] The charge generating layer is, for example, a layer containing a charge generating material and a binder resin. Furthermore, the charge generating layer may be a vapor-deposited layer of the charge generating material. The vapor-deposited layer of the charge generating material is suitable for the case where an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-luminescence) image array is used.

[0387] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed ring aromatic pigments such as dibromoanthraquinone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0388] Among them, in order to cope with laser exposure in the near-infrared region, as a charge generating material, for example, a metal phthalocyanine pigment or a metal-free phthalocyanine pigment is preferably used. Specifically, for example, at least one selected from the group consisting of hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine and oxytitanium phthalocyanine is preferred, hydroxygallium phthalocyanine and / or chlorogallium phthalocyanine is more preferred, and hydroxygallium phthalocyanine is further preferred. Hydroxygallium phthalocyanine has an absorption peak at a wavelength of 678nm.

[0389] In order to cope with laser exposure in the near-ultraviolet region, the charge generating material is preferably a condensed-ring aromatic pigment such as dibromoanthraquinone; a thioindigo pigment; a porphyrazine compound; zinc oxide; a trigonal selenium; a disazo pigment, and the like.

[0390] Even when using an incoherent light source such as an LED or an organic EL image array whose central wavelength of light emission is within the range of 450nm to 780nm, the above-mentioned charge generating material can be used. However, from the viewpoint of resolution, when a photosensitive layer is used as a thin film of 20μm or less, the electric field intensity in the photosensitive layer becomes high, and the charge is reduced due to the injection of charges from the substrate, which easily causes image defects called black spots. This becomes significant when using a charge generating material that easily generates dark current in a p-type semiconductor such as trigonal selenium and phthalocyanine pigments.

[0391] In contrast, when n-type semiconductors such as condensed aromatic pigments, perylene pigments, and azo pigments are used as charge generating materials, dark current is less likely to be generated, and image defects called black spots can be suppressed even in thin films. The n-type is determined by the polarity of the photocurrent flowing using the commonly used time-of-flight method, and semiconductors that are more likely to flow with electrons as carriers than holes are defined as n-type.

[0392] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins, and can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane.

[0393] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (condensation products of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. Here, "insulation" means that the volume resistivity is 1×10 13 Ω·cm or more.

[0394] These binder resins may be used alone or in combination of two or more.

[0395] The mixing ratio of the charge generating material to the binder resin is preferably in the range of 10:1 to 1:10, for example, in terms of mass ratio.

[0396] Other known additives may be contained in the charge generating layer.

[0397] The formation of the charge generating layer is not particularly limited, and a known formation method can be used, but for example, a coating film of a charge generating layer-forming coating liquid in which the above-mentioned components are added to a solvent is formed, the coating film is dried, and heating is performed as needed. The charge generating layer can be formed by vapor deposition of the charge generating material. The formation of the charge generating layer by vapor deposition is particularly suitable for the case where, for example, a condensed ring aromatic pigment or a perylene pigment is used as the charge generating material.

[0398] Examples of the solvent used for preparing the charge generating layer-forming coating solution 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, dichloromethane, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0399] As a method for dispersing particles (e.g., charge generating material) in the coating liquid for forming the charge generating layer, for example, a medium disperser such as a ball mill, a vibrating ball mill, a grinder, a sand mill, a horizontal sand mill, or a stirrer, an ultrasonic disperser, a roll mill, a high-pressure homogenizer, or a medium-free disperser can be used. As a high-pressure homogenizer, for example, a collision method in which the dispersion 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, etc. can be cited.

[0400] When performing the dispersion, it is effective to set the average particle size of the charge generating material in the charge generating layer forming coating liquid to 0.5 μm or less, for example, preferably 0.3 μm or less, more preferably 0.15 μm or less.

[0401] Examples of a method for applying the charge generating layer forming coating liquid onto the undercoat layer (or the intermediate layer) include common methods such as dip coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, and curtain coating.

[0402] From the viewpoint of productivity in continuously forming the charge generating layer and the charge transporting layer, the method for forming the charge generating layer is preferably a dip coating method, for example.

[0403] The average thickness of the charge generating layer is set, for example, in the range of 0.05 μm to 5.0 μm, 0.10 μm to 2.0 μm, or 0.15 μm to 1.0 μm.

[0404] [Charge transport layer]

[0405] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material.

[0406] As charge transport materials, there can be cited quinone compounds such as p-benzoquinone, chloranil, tetrabromobenzoquinone, anthraquinone, etc.; tetracyanoterephthalene compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; anthrone compounds; benzophenone compounds; cyanoethylene compounds; vinyl compounds and other electron transport compounds. As charge transport materials, there can also be cited triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, hydrazone compounds and other hole transport compounds. These charge transport materials can be used alone or in combination of two or more, but are not limited thereto.

[0407] As the polymer charge transport material, known chemical substances having charge transport properties such as poly-N-vinyl carbazole and polysilane can be cited. For example, polyester-based polymer charge transport materials are preferred. The polymer charge transport material can be used alone or in combination with a binder resin.

[0408] As charge transport materials or polymer charge transport materials, there can also be mentioned polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triallylamine compounds (especially triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyanide compounds, benzofuran compounds, aniline compounds, butadiene compounds and resins having groups derived from these substances. Specifically, paragraphs 0078 to 0080 of Japanese Patent Application Publication No. 2021-117377, paragraphs 0046 to 0048 of Japanese Patent Application Publication No. 2019-035900, paragraphs 0052 to 0053 of Japanese Patent Application Publication No. 2019-012141, paragraphs 0122 to 0134 of Japanese Patent Application Publication No. 2021-071565, and paragraphs 0136 to 0137 of Japanese Patent Application Publication No. 2021-0 Compounds described in paragraphs 0101 to 0110 of Japanese Patent Application No. 15223, paragraph 0116 of Japanese Patent Application No. 2013-097300, paragraphs 0309 to 0316 of International Publication No. 2019 / 070003, paragraphs 0103 to 0107 of Japanese Patent Application No. 2018-159087, and paragraphs 0102 to 0113 of Japanese Patent Application No. 2021-148818.

[0409] From the viewpoint of charge mobility, the charge transport material, for example, preferably includes at least one selected from the group consisting of a compound (C1) represented by the following formula (C1), a compound (C2) represented by formula (C2), a compound (C3) represented by formula (C3) and a compound (C4) represented by formula (C4).

[0410] [Chemical formula 27]

[0411] Formula (c1)

[0412] In formula (C1), Ar T1 ,Ar T2 and Ar T3 are independently aryl, -C 6 H 4 -C(R T4 )=C(R T5 )(R T6 ) or -C 6 H 4 -CH=CH-CH=C(R T7 )(R T8 ). T4 , R T5 , R T6 , R T7 and R T8 are independently a hydrogen atom, an alkyl group or an aryl group. T5 and R T6 When the aromatic groups are aromatic, the aromatic groups can be connected to each other through -C(R 51 )(R 52 )-and / or-C(R 61 )=C(R 62 )- is linked to a divalent group. 51 , R 52 , R 61 and R 62 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0413] The group in formula (C1) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0414] From the viewpoint of charge mobility, the compound (C1) preferably has at least one aryl group or -C 6 H 4 -CH=CH-CH=C(R T7 )(R T8), and more preferably a compound (C′1) represented by the following formula (C′1).

[0415] [Chemical formula 28]

[0416]

[0417] In formula (C′1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132 Each of Tj1, Tj2, Tj3, Tk1, Tk2 and Tk3 is independently 0, 1 or 2.

[0418] [Chemical formula 29]

[0419] Formula (C2)

[0420] In formula (C2), R T201 , R T202 , R T211 and R T212 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 or 2 carbon atoms, an aryl group, a -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(R T25 ). T21 , R T22 , R T23 , R T24 and R T25 are independently a hydrogen atom, an alkyl group or an aryl group. T221 and R T222 Each of them is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. Tm1, Tm2, ​​Tn1, and Tn2 are each independently 0, 1, or 2.

[0421] The group in formula (C2) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0422] From the viewpoint of charge mobility, the compound (C2) preferably has at least one alkyl group, aryl group or -CH=CH-CH=C(R T24 )(R T25 ), more preferably a compound having two alkyl groups, aryl groups or -CH=CH-CH=C(R T24 )(R T25 ) compounds.

[0423] [Chemical formula 30]

[0424] Formula (c3)

[0425] In formula (C3), R T301 , R T302 , R T311 and R T312 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 or 2 carbon atoms, an aryl group, a -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ). T31 , R T32 , R T33 , R T34 and R T35 are independently a hydrogen atom, an alkyl group or an aryl group. T321 , R T322 and R T331 Each of them is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, To2, Tp1, Tp2, Tq1, Tq2, and Tr1 are each independently 0, 1, or 2.

[0426] The group in formula (C3) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0427] [Chemical formula 31]

[0428] Formula (c4)

[0429] In formula (C4), R T401 , R T402 , R T411 and R T412are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 or 2 carbon atoms, an aryl group, a -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ). T41 , R T42 , R T43 , R T44 and R T45 are independently a hydrogen atom, an alkyl group or an aryl group. T421 , R T422 and R T431 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 are each independently 0, 1, or 2.

[0430] The group in formula (C4) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0431] The content of the charge transport material contained in the charge transport layer is preferably, for example, 20% by mass or more and 70% by mass or less relative to the total mass of the charge transport layer.

[0432] The charge transport layer contains at least a polyarylate resin as a binder resin, and preferably contains at least a polyarylate resin (1), for example.

[0433] The proportion of the polyarylate resin in the total amount of the binder resin contained in the charge transport layer is, for example, preferably 60 mass % or more, more preferably 70 mass % or more, further preferably 80 mass % or more, particularly preferably 90 mass % or more.

[0434] The proportion of the polyarylate resin (1) in the total amount of the binder resin contained in the charge transport layer is, for example, preferably 60 mass % or more, more preferably 70 mass % or more, further preferably 80 mass % or more, particularly preferably 90 mass % or more.

[0435] One embodiment of the charge transport layer contains a polyarylate resin and a polycarbonate resin as a binder resin. In this case, the mass ratio of the two resins is preferably, for example, polyarylate resin:polycarbonate resin=95:5 to 40:60.

[0436] When the polyarylate resin (1) and the polycarbonate resin are used in combination, the mass ratio of the two resins is preferably, for example, polyarylate resin (1):polycarbonate resin=95:5 to 40:60.

[0437] As the polycarbonate resin, for example, a polycarbonate resin having a continuous structural unit having an aromatic ring is preferred, and specific examples thereof include the polycarbonate resins used in the Examples described below.

[0438] The charge transport layer may include other binding resins other than polyarylate resin and polycarbonate resin. As other binding resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenolic-formaldehyde resins, styrene-alkyd resins, poly-N-vinyl carbazole, polysilane, etc., other than polyarylate resins, may be cited. These binding resins are used alone or in combination.

[0439] The charge transport layer may contain other known additives, such as antioxidants, leveling agents, defoaming agents, fillers, and viscosity modifiers.

[0440] The charge transport layer can be formed by any known method without particular limitation, but can be formed by, for example, forming a coating film of a charge transport layer-forming coating liquid obtained by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0441] As the solvent for preparing the coating solution for forming the charge transport layer, there can be mentioned aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and dichloroethane; cyclic or linear ethers such as tetrahydrofuran and diethyl ether, and other common organic solvents. These solvents can be used alone or in combination of two or more.

[0442] Examples of a coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as dip coating, blade coating, wire bar coating, spray coating, bead coating, air knife coating, and curtain coating.

[0443] From the viewpoint of productivity of the photoreceptor, the charge transport layer is preferably formed by, for example, a dip coating method.

[0444] From the viewpoint of extending the life of the photoreceptor, the average thickness of the charge transport layer is, for example, 30 μm or more, preferably 34 μm or more, and more preferably 38 μm or more.

[0445] From the viewpoint of suppressing uneven layer thickness, the average thickness of the charge transport layer is, for example, preferably 50 μm or less, more preferably 47 μm or less, and further preferably 45 μm or less.

[0446] The average thickness of the charge transport layer is the arithmetic mean of the values ​​measured by an optical interference film thickness meter, and the measurement locations are 12 locations in total at 90° scales along the circumferential direction at position (M), position (U) and position (L).

[0447] [Protective layer]

[0448] The protective layer is provided on the photosensitive layer as required. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during charging or to further improve the mechanical strength of the photosensitive layer.

[0449] Therefore, for example, a layer composed of a cured film (crosslinked film) is preferably used as the protective layer. Examples of these layers include the layers shown in the following 1) or 2).

[0450] 1) A layer consisting 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 a crosslinked body of the reactive group-containing charge transport material)

[0451] 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material having a reactive group but not having a charge transport skeleton (i.e., a layer comprising a non-reactive charge transport material and a polymer or a crosslinked body of the non-charge transport material having a reactive group)

[0452] Examples of the reactive group of the charge transport material containing a reactive group include a chain polymerizable group, an epoxy group, -OH, -OR [wherein R represents an alkyl group], -NH 2 、-SH、-COOH、-SiR Q1 3-Qn (OR Q2 ) Qn [Among them, 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, a trialkylsilyl group, Qn represents an integer of 1 to 3] and the like.

[0453] The chain polymerizable group is not particularly limited as long as it is a functional group capable of free radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specifically, a group containing at least one selected from vinyl, vinyl ether, vinyl thioether, phenylvinyl, vinylphenyl, acryloyl, methacryloyl, and derivatives thereof may be cited. Among them, since it has excellent reactivity, the chain polymerizable group is preferably a group containing at least one selected from vinyl, phenylvinyl, vinylphenyl, acryloyl, methacryloyl, and derivatives thereof.

[0454] The charge transport skeleton of the charge transport material containing a reactive group is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include skeletons derived from nitrogen-containing hole transport compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, and structures conjugated with nitrogen atoms. Among them, for example, a triarylamine skeleton is preferred.

[0455] The reactive group-containing charge transport material, the non-reactive charge transport material, and the reactive group-containing non-charge transport material having these reactive groups and charge transport skeletons may be selected from known materials.

[0456] Other known additives may be contained in the protective layer.

[0457] The protective layer can be formed by any known method without particular limitation, and can be formed by, for example, forming a coating film of a protective layer-forming coating liquid obtained by adding the above components to a solvent, drying the coating film, and performing a curing treatment such as heating as necessary.

[0458] Examples of the solvent used to prepare the protective layer-forming coating solution 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; alcohol solvents such as isopropyl alcohol and butanol, etc. These solvents may be used alone or in combination of two or more.

[0459] The protective layer-forming coating liquid may be a solvent-free coating liquid.

[0460] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (eg, charge transport layer) include common methods such as dip coating, push coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0461] The thickness of the protective layer is preferably set within a range of, for example, 1 μm to 20 μm, and more preferably within a range of 2 μm to 10 μm.

[0462] <Image forming apparatus, process cartridge>

[0463] 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 a toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. As the electrophotographic photoreceptor, the electrophotographic photoreceptor according to the present embodiment is applicable.

[0464] The image forming device involved in this embodiment is applicable to the following well-known image forming devices: a device equipped with a fixing device for fixing the toner image transferred to the surface of a recording medium; a device using a direct transfer method for directly transferring the toner image formed on the surface of an electrophotographic photosensitive body to the recording medium; a device using an intermediate transfer method for transferring the toner image formed on the surface of an electrophotographic photosensitive body once to the surface of an intermediate transfer body, and for a second time transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a device equipped with a cleaning device for cleaning the surface of the electrophotographic photosensitive body after transferring the toner image but before charging; a device equipped with a static elimination device for removing static electricity by irradiating the surface of the electrophotographic photosensitive body with static elimination light after transferring the toner image and before charging; and a device equipped with an electrophotographic photosensitive body heating component for increasing the temperature of the electrophotographic photosensitive body and lowering the relative temperature, etc.

[0465] In the case of an intermediate transfer type device, the transfer device, for example, is applicable to the following structure, which has an intermediate transfer body having a toner image transferred on its surface, a primary transfer device for transferring the toner image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body, and a secondary transfer device for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0466] The image forming apparatus according to the present embodiment may be any of a dry developing system image forming apparatus and a wet developing system (development system using a liquid developer) image forming apparatus.

[0467] In the image forming apparatus according to the present embodiment, for example, the portion having the electrophotographic photoreceptor may be a cartridge structure (processing cartridge) that is detachable from the image forming apparatus. As the processing cartridge, for example, a processing cartridge having the electrophotographic photoreceptor according to the present embodiment is preferably used. In the processing cartridge, in addition to the electrophotographic photoreceptor, for example, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device may be provided.

[0468] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0469] Figure 2 It is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0470] like Figure 2 As shown, the image forming apparatus 100 according to the present embodiment includes a process box 300 having 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 arranged at a position capable of exposing the electrophotographic photoreceptor 7 from the opening of the process box 300, and the transfer device 40 is arranged at a position opposed to the electrophotographic photoreceptor 7 with the intermediate transfer body 50 interposed therebetween, and the intermediate transfer body 50 is arranged so that a part thereof contacts the electrophotographic photoreceptor 7. Although not shown in the figure, a secondary transfer device is further provided for transferring 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 in the figure) correspond to an example of a transfer device.

[0471] Figure 2 The process box 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging device), the developing device 11 (an example of a developing device), and the cleaning device 13 (an example of a cleaning device) in a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is configured to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0472] exist Figure 2 In the example shown, as the image forming apparatus, a fibrous member 132 (roller-shaped) for supplying lubricant 14 to the surface of electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush-shaped) for assisting cleaning are provided, but these may be arranged as necessary.

[0473] Hereinafter, each structure of the image forming apparatus according to the present embodiment will be described.

[0474] -Electrified Devices-

[0475] As the charging device 8, for example, a contact type charging device such as a charging roller, a charging brush, a charging film, a charging rubber blade, a charging hose, etc. using conductive or semi-conductive charging can be used. In addition, a non-contact type roller charging device, a scorotron charging device or a corotron charging device using corona discharge, etc., which are known per se, can also be used.

[0476] -Exposure device-

[0477] As the exposure device 9, for example, there can be cited an optical system device that exposes semiconductor laser, LED light, liquid crystal shutter light, etc. on the surface of the electrophotographic photoreceptor 7 to a prescribed pattern. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared light with an oscillation wavelength near 780nm is the mainstream. However, it is not limited to this wavelength. As an oscillation wavelength laser or a blue laser in the 600nm band, a laser with an oscillation wavelength in the range of more than 400nm and less than 450nm can also be used. In addition, a surface-emitting laser light source of the type that can output multiple beams in order to form a color image is also effective.

[0478] -Developing device-

[0479] As the developing device 11, for example, a general developing device that develops by contact or non-contact with a developer can be cited. As the developing device 11, there is no particular limitation as long as it has the above-mentioned function, and it can be selected according to the purpose. For example, a known developer having a function of attaching a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, etc. can be cited. Among them, for example, a developer using a developing roller that holds the developer on the surface is preferred.

[0480] The developer used in the developing device 11 may be a single-component developer containing only a toner, or a two-component developer containing a toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. These developers are suitable for known developers.

[0481] -Cleaning device-

[0482] The cleaning device 13 may be a cleaning blade type device including a cleaning blade 131. In addition to the cleaning blade type, a brush cleaning method or a simultaneous development cleaning method may be used.

[0483] -Transfer device-

[0484] Examples of the transfer device 40 include a contact transfer charger using a belt, a roller, a film, a rubber blade, etc.; a corotron transfer charger using corona discharge; a corotron transfer charger, etc., which are known per se.

[0485] -Intermediate transfer body-

[0486] As the intermediate transfer body 50, a belt-shaped transfer body (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity can be used. In addition, as a form of the intermediate transfer body, a roller-shaped transfer body can be used.

[0487] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0488] Figure 3 The image forming apparatus 120 shown is a multi-color image forming apparatus of a tandem type equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged on the intermediate transfer body 50, respectively, and a single electrophotographic photoreceptor is used for each color. The image forming apparatus 120 has the same structure as the image forming apparatus 100 except for the tandem type.

[0489] Example

[0490] Hereinafter, embodiments of the present invention will be described in detail based on examples, but embodiments of the present invention are not limited to these examples.

[0491] In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0492] In the following description, unless otherwise specified, synthesis, production, treatment, measurement, etc. were performed at room temperature (25° C.±3° C.).

[0493] <Synthesis of polyarylate resin (1)>

[0494] Polyarylate resins (1-1) to (1-3) shown in Table 1 were synthesized.

[0495] A2-3 described in Table 1 is a specific example of the dicarboxylic acid unit (A) described above.

[0496] B1-4 and the like described in Table 1 are specific examples of the diol unit (B) already described.

[0497] [Table 1]

[0498] Polyarylate resin Dicarboxylic acid unit (A) Diol unit (B) (1-1) A2-3 B1-4 (1-2) A2-3 B1-2 (1-3) A2-3 B2-6

[0499] <Manufacturing of photoreceptors>

[0500] [Example 1]

[0501] -Formation of lower coating layer-

[0502] As the 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.

[0503] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 / g, manufactured by TAYCA CORPORATION) and 500 parts of toluene were mixed and stirred, and 1.3 parts of a silane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) were added and stirred for 2 hours. Then, the toluene was distilled under reduced pressure and sintered at 120° C. for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.

[0504] 110 parts of surface-treated zinc oxide and 500 parts of tetrahydrofuran were mixed and stirred, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring at 50° C. for 5 hours. Then, the solid content was filtered out by vacuum filtration and dried at 60° C. to obtain zinc oxide with alizarin.

[0505] 60 parts of zinc oxide to impart alizarin, 13.5 parts of a curing agent (blocked isocyanate, trade name: SUMIDUR3175, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 15 parts of a butyral resin (trade name: S-LEC BM-1, manufactured by SEKISUI CHEMICAL CO., LTD.) were dissolved in 100 parts of a solution containing 68 parts of methyl ethyl ketone and 5 parts of methyl ethyl ketone, and the mixture was stirred for 2 hours. The glass beads were dispersed by a sand mill for 2 hours to obtain a dispersion. 0.005 parts of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: Tospearl145, manufactured by Momentive performance Materials Inc.) were added to the dispersion as a catalyst to obtain a coating solution for forming an undercoat layer. The coating solution for forming an undercoat layer was applied to the outer peripheral surface of the conductive substrate by a dip coating method, and dried and cured at 170°C for 40 minutes to form an undercoat layer with an average thickness of 20 μm.

[0506] -Formation of Charge Generation Layer-

[0507] 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 a vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Company Limited) as a binder resin and 200 parts of n-butyl acetate was dispersed for 4 hours using a sand mill using glass beads having a diameter of 1 mm. 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.

[0508] The conductive substrate having the lower coating layer is immersed in the coating liquid, and when the conductive substrate is pulled upward from the coating liquid in the direction of gravity, the pulling speed is controlled so that the pulling speed of the upper end side is slower than that of the central part, and the pulling speed of the lower end side is faster than that of the central part, so as to obtain the absorbance ratio recorded in Table 2. Here, the "central part" is defined as a region occupying 50% of the total length L in the axial direction of the photoreceptor.

[0509] -Formation of Charge Transport Layer-

[0510] 60 parts of polyarylate resin (1-1) as a binder resin and 40 parts of CTM-1 as a charge transport material were dissolved in 270 parts of tetrahydrofuran and 30 parts of toluene to obtain a coating liquid for forming a charge transport layer. The coating liquid for forming a charge transport layer was dip-coated on the charge generating layer. Then, it was dried at 145°C for 30 minutes to form a charge transport layer. The average thickness of the charge transport layer is as shown in Table 2.

[0511] [Chemical formula 32]

[0512]

[0513] [Examples 2 to 5 and Comparative Example 1]

[0514] A photoreceptor was prepared in the same manner as in Example 1 except that the speed ratio of the pulling speed from the coating liquid was changed when the charge generating layer was dip-coated.

[0515] [Examples 6-7]

[0516] Each photoreceptor was prepared in the same manner as in Example 1 except that the type of the polyarylate resin was changed to the weight described in Table 2 in forming the charge transport layer.

[0517] [Examples 8 to 9]

[0518] Each photoreceptor was prepared in the same manner as in Example 1 except that a part of the polyarylate resin was replaced with a polycarbonate resin in forming the charge transport layer. The structures of the polycarbonate resins (1) and (2) are as follows.

[0519] [Chemical formula 33]

[0520]

[0521] In the formula, 75, 25, 50, and 50 represent polymerization molar ratios (mol %).

[0522] <Photoreceptor performance evaluation>

[0523] The photoreceptor of each example or each comparative example was installed in an electrophotographic image forming apparatus DocuCentre-VC7775 (FUJIFILM Business Inmovation).

[0524] [Abrasion resistance]

[0525] Under a low temperature and low humidity environment of 10°C and 15% relative humidity, 10,000 full-surface halftone images of 30% concentration images of yellow, magenta, cyan and black were continuously output on A3-sized plain paper, totaling 40,000 images. Before and after the image was formed, the average thickness (nm) of the charge transport layer was measured, and the difference in the average thickness before and after the image was formed was set as the wear amount (nm). As a film thickness measuring machine, PERMASCOPE manufactured by Fischer Instruments KK was used. The wear amount was classified as follows. The results are shown in Table 2.

[0526] A: Wear loss is less than 800nm

[0527] B: Wear loss is more than 800nm ​​and less than 1600nm

[0528] C: Wear loss is greater than 1600nm and less than 2400nm

[0529] D: Wear loss is more than 2400nm

[0530] [Uneven charging]

[0531] A surface potential probe connected to a surface potentiometer (TREQ334 manufactured by TREQ INC.) was set at a position corresponding to the position (U) and the position (L) and 1 mm away from the surface of the photoreceptor.

[0532] Ten sheets of halftone images with an image density of 30% were output on A3-sized plain paper at a temperature of 24°C and a relative humidity of 55%. When the image was formed on the last sheet, the charge potential of the photoreceptor was measured, and the difference between the charge potential at position (U) and the charge potential at position (L) was calculated and classified as follows. The results are shown in Table 2.

[0533] A: The difference in charged potential is less than 10V

[0534] B: The difference in charge potential is greater than 10V and less than 20V

[0535] C: The difference in charge potential is 20V or more

[0536] "Iu / Im / Il" in Table 2 is a relative value when the value of Im is set to 1.

[0537] [Table 2]

[0538]

[0539] The electrophotographic photoreceptor, process cartridge, and image forming apparatus of the present invention include the following embodiments. Each formula representing the compound is the same as the above-mentioned formula having the same number.

[0540] (1) An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer having a charge generating layer and a charge transporting layer disposed on the conductive substrate, wherein:

[0541] The average thickness of the charge transport layer is 30 μm or more.

[0542] The charge transport layer contains a polyarylate resin,

[0543] The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1) and formula (2):

[0544] Formula (1): Iu≤0.95×Im

[0545] Formula (2): 1.05×Im≤Il

[0546] When the total length of the electrophotographic photoreceptor in the axial direction is defined as L,

[0547] Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor,

[0548] Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end,

[0549] I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

[0550] (2) The electrophotographic photoreceptor according to (1), wherein

[0551] The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1-3) and formula (2-3),

[0552] Formula (1-3): 0.75×Im<Iu≤0.95×Im

[0553] Formula (2-3): 1.05×Im≤Il<1.25×Im

[0554] When the total length of the electrophotographic photoreceptor in the axial direction is defined as L,

[0555] Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor,

[0556] Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end,

[0557] I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

[0558] (3) The electrophotographic photoreceptor according to (1) or (2), wherein

[0559] The charge generating layer contains hydroxygallium phthalocyanine.

[0560] (4) The electrophotographic photoreceptor according to any one of (1) to (3), wherein

[0561] The weight average molecular weight of the polyarylate resin contained in the charge transport layer is 80,000 or more.

[0562] (5) The electrophotographic photoreceptor according to any one of (1) to (4), wherein

[0563] The charge transport layer further contains a polycarbonate resin.

[0564] (6) The electrophotographic photoreceptor according to any one of (1) to (5), wherein

[0565] The polyarylate resin includes a polyarylate resin (1) having a dicarboxylic acid unit (A) represented by the formula (A) and a diol unit (B) represented by the formula (B).

[0566] (7) The electrophotographic photoreceptor according to (6), wherein

[0567] The polyarylate resin (1) has the dicarboxylic acid unit (A) comprising 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).

[0568] (8) The electrophotographic photoreceptor according to (6) or (7), wherein

[0569] The polyarylate resin (1) comprises at least one diol unit (B) 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).

[0570] (9) The electrophotographic photoreceptor according to any one of (6) to (8), wherein

[0571] The polyarylate resin (1) has the dicarboxylic acid unit (A) comprising at least one selected from the group consisting of a dicarboxylic acid unit (A2) represented by the formula (A2) and a dicarboxylic acid unit (A4) represented by the formula (A4).

[0572] (10) The electrophotographic photoreceptor according to any one of (6) to (9), wherein

[0573] The polyarylate resin (1) has the diol unit (B) comprising at least one selected from the group consisting of a diol unit (B1) represented by the formula (B1) and a diol unit (B2) represented by the formula (B2).

[0574] (11) A process cartridge comprising the electrophotographic photoreceptor according to any one of (1) to (10), wherein:

[0575] The process cartridge is attachable to and detachable from the image forming apparatus.

[0576] (12) An image forming apparatus comprising:

[0577] The electrophotographic photoreceptor according to any one of (1) to (10);

[0578] A charging device for charging the surface of the electrophotographic photoreceptor;

[0579] An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0580] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and

[0581] The transfer device transfers the toner image to the surface of a recording medium.

[0582] According to the invention involved in (1), (3), (5), (6), (7), (8), (9) or (10), there is provided an electronic photographic photosensitive body which has excellent wear resistance and is less likely to produce uneven charging than an electronic photographic photosensitive body that does not satisfy one or both of formula (1) and formula (2).

[0583] According to the invention of (2), there is provided an electrophotographic photoreceptor which is excellent in abrasion resistance and is less likely to cause charging unevenness than an electrophotographic photoreceptor which does not satisfy one or both of the formulas (1-3) and (2-3).

[0584] According to the invention as set forth in (4), there is provided an electrophotographic photoreceptor having excellent abrasion resistance compared with a case where the weight average molecular weight of the polyarylate resin is less than 80,000.

[0585] According to the invention of (11), a process cartridge is provided in which the electrophotographic photoreceptor has excellent wear resistance and is less likely to produce uneven charging, compared with a process cartridge having an electrophotographic photoreceptor that does not satisfy one or both of the equations (1) and (2).

[0586] According to the invention involved in (12), there is provided an image forming apparatus having an electrophotographic photoreceptor with excellent wear resistance and less prone to uneven charging, compared with an image forming apparatus having an electrophotographic photoreceptor that does not satisfy one or both of equations (1) and (2).

[0587] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer having a charge generating layer and a charge transporting layer disposed on the conductive substrate, wherein: The average thickness of the charge transport layer is 30 μm or more. The charge transport layer contains a polyarylate resin, The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1) and formula (2): Formula (1): Iu≤0.95×Im Formula (2): 1.05×Im≤Il When the total length of the electrophotographic photoreceptor in the axial direction is defined as L, Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor, Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end, I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

2. The electrophotographic photoreceptor according to claim 1, wherein The absorption spectrum measured after the photosensitive layer is peeled off and dissolved in tetrahydrofuran satisfies the following formula (1-3) and formula (2-3), Formula (1-3): 0.75×Im<Iu≤0.95×Im Formula (2-3): 1.05×Im≤Il<1.25×Im When the total length of the electrophotographic photoreceptor in the axial direction is defined as L, Im is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from the center in the axial direction of the electrophotographic photoreceptor, Iu is the absorbance at a wavelength of 678 nm of the photosensitive layer peeled from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward one end, I1 is the absorbance at a wavelength of 678 nm associated with the photosensitive layer peeled off from a position of 0.40 L from the center in the axial direction of the electrophotographic photoreceptor toward the other end.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein The charge generating layer contains hydroxygallium phthalocyanine.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein The weight average molecular weight of the polyarylate resin contained in the charge transport layer is 80,000 or more.

5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein The charge transport layer further contains a polycarbonate resin.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The polyarylate resin comprises a polyarylate 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), [Chemical formula 1] Formula (A) Formula (B) In formula (A), Ar A1 and Ar A2 are each independently 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 are each independently an aromatic ring which may have a substituent, L B is a single bond, oxygen atom, sulfur atom or -C(Rb 1 )(Rb 2 )-,n B1 is 0, 1 or 2, Rb 1 and Rb 2 are each independently 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, and Rb 1 With Rb 2 They may be bonded to form a cyclic alkyl group.

7. The electrophotographic photoreceptor according to claim 6, wherein The polyarylate resin (1) comprises at least one dicarboxylic acid unit (A) selected from the group consisting of a dicarboxylic acid unit (A1) represented by the following formula (A1), a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4). [Chemical formula 2] Formula (A1) Formula (A2) Formula (A3) Formula (A4) In formula (A1), n 101 is an integer greater than or equal to 0 and less than or equal to 4, n 101 Ra 101 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, and n 201 Ra 201 and n 202 Ra 202 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, and n 301 Ra 301 and n 302 Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, In formula (A4), n 401 is an integer greater than or equal to 0 and less than or equal to 6, 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.

8. The electrophotographic photoreceptor according to claim 6 or 7, wherein The polyarylate resin (1) comprises at least one diol unit (B) selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8), [Chemical formula 3] Formula (B1) Formula (B2) Formula (B3) Formula (B4) [Chemical formula 4] Formula (B5) Formula (B6) Formula (B7) Formula (B8) 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 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B2), Rb 102 is a straight-chain 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 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer of 7 to 15, Rb 403 , Rb 503 , Rb 803 and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, Rb 404 , Rb 504 , Rb 804 and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, 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 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, 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 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 Each of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

9. The electrophotographic photoreceptor according to any one of claims 6 to 8, wherein The polyarylate resin (1) has the dicarboxylic acid unit (A) comprising at least one selected from the group consisting of a dicarboxylic acid unit (A2) represented by the following formula (A2) and a dicarboxylic acid unit (A4) represented by the following formula (A4), [Chemical formula 5] Formula (A2) Formula (A4) In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, and n 201 Ra 201 and n 202 Ra 202 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, In formula (A4), n 401 is an integer greater than or equal to 0 and less than or equal to 6, 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.

10. The electrophotographic photoreceptor according to any one of claims 6 to 9, wherein The polyarylate resin (1) has the diol unit (B) comprising 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), [Chemical formula 6] Formula (B1) Formula (B2) 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 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, In formula (B2), Rb 102 is a straight-chain 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 of them is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

11. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 10, wherein: The process cartridge is attachable to and detachable from the image forming apparatus.

12. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 10; 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 charged surface of the electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and The transfer device transfers the toner image to the surface of a recording medium.

Images