Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention discloses an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus, the electrophotographic photoreceptor includes a conductive substrate, and a laminated photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, the charge transport layer containing a charge transport material and a polyester resin (1), the molecular weight distribution curve of the polyester resin (1) contained in the charge transport layer has at least two peaks, and when the molecular weight at the maximum point of the peak with the minimum molecular weight is Mmin, the molecular weight at the maximum point of the peak with the maximum molecular weight is Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the charge transport layer is Mw, the molecular weight at the maximum point of the peak with the maximum molecular weight is Mw. 50,000 < = Mw < = 200,000, and 0.4 < = (Mmax-Mmin) / Mw < = 5.0.

Description

Technical Field

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

[0002] Japanese Patent Publication No. 2023-047285 discloses an electrophotographic photoreceptor comprising a conductive substrate and a laminated photosensitive layer having a charge generating layer and a charge transport layer, wherein the charge transport layer comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by a given formula (A) and a diol unit (B) represented by a given formula (B), and a charge transport material. When the weight average molecular weight Mw of the polyester resin (1) contained in the charge transport layer is set to A (10,000), the value of the ratio M1 / M2 of the mass M1 of the charge transport material contained in the charge transport layer to the mass M2 of the charge transport layer is set to Cs, and the average thickness of the charge transport layer is set to Ds (μm), 5≤A≤40, 0.28≤Cs≤0.55, 27≤Ds≤50, and 2.5≤(A×Ds) / (Cs×100)≤70.0 are satisfied.

[0003] Japanese Patent Gazette No. 2023-130296 discloses an electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a laminated photosensitive layer having a charge generating layer and a charge transport layer disposed on the undercoat layer, wherein the charge transport layer contains a charge transport material and a polyester resin. When the average thickness of the charge transport layer is As (μm) and the average thickness of the undercoat layer is Bs (μm), 27≤As≤50, 10≤Bs≤40, and 0.70≤As / Bs≤4.80 are satisfied. Summary of the Invention

[0004] The present invention aims to provide an electrophotographic photoreceptor having excellent uniformity of potential distribution on its surface and hardly causing image defects even when dropped in a high-temperature, high-humidity environment or when left in a high-temperature, high-humidity environment for a long period of time.

[0005] According to a first embodiment of the present invention, an electrophotographic photoreceptor is provided, comprising a conductive substrate and a laminated photosensitive layer having a charge generating layer and a charge transport layer arranged on the conductive substrate, wherein the charge transport layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B), wherein the molecular weight distribution curve of the polyester resin (1) contained in the charge transport layer has at least two peaks, and when the molecular weight of the maximum point of the peak with the smallest molecular weight is defined as Mmin and the molecular weight of the maximum point of the peak with the largest molecular weight is defined as Mmax, and when the weight-average molecular weight of the polyester resin (1) contained in the charge transport layer is defined as Mw, the following conditions are satisfied: 50,000 ≤ Mw ≤ 200,000, and 0.4 ≤ (Mmax - Mmin) / Mw ≤ 5.0.

[0006] Formula (A)

[0007] Formula (B)

[0008] 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 0, 1, or 2.

[0009] 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group.

[0010] According to a second aspect of the present invention, the electrophotographic photoreceptor of the first aspect satisfies 0.5≤(Mmax−Mmin) / Mw≤4.5.

[0011] According to a third aspect of the present invention, the electrophotographic photoreceptor of the first or second aspect satisfies 80,000≦Mw≦150,000.

[0012] According to a fourth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to third aspects, the dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4).

[0013] Formula (A1)

[0014] Formula (A2)

[0015] Formula (A3)

[0016] Formula (A4)

[0017] 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.

[0018] In formula (A2), n 201 and n 202 are each independently an integer of 0 or more and 4 or less, 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.

[0019] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, 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.

[0020] 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.

[0021] According to a fifth aspect of the present invention, in the electrophotographic photoreceptor of the fourth aspect, the dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4).

[0022] According to a sixth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to fifth aspects, the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7) and a diol unit (B8) represented by formula (B8).

[0023] Formula (B1)

[0024] Formula (B2)

[0025] Formula (B3)

[0026] Formula (B4)

[0027] Formula (B5)

[0028] Formula (B6)

[0029] Formula (B7)

[0030] Formula (B8)

[0031] In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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.

[0032] In formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less carbon atoms, Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, Rb402 , 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.

[0033] 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.

[0034] In formula (B4), Rb 104 and Rb 204 are 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.

[0035] 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.

[0036] 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.

[0037] In formula (B7), Rb 407 , 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.

[0038] 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.

[0039] According to a seventh aspect of the present invention, in the electrophotographic photoreceptor of the sixth aspect, the diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6).

[0040] According to the eighth embodiment of the present invention, an electronic photographic photosensitive body is provided, which comprises a conductive substrate and a single-layer photosensitive layer arranged on the conductive substrate, wherein the single-layer photosensitive layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B), and the molecular weight distribution curve of the polyester resin (1) contained in the single-layer photosensitive layer has at least two peaks, and when the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin and the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the single-layer photosensitive layer is set to Mw, 50,000 ≤ Mw ≤ 200,000, and 0.4 ≤ (Mmax-Mmin) / Mw ≤ 5.0 are satisfied.

[0041] Formula (A)

[0042] Formula (B)

[0043] 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 0, 1, or 2.

[0044] In formula (B), Ar B1 and Ar B2 are each independently an aromatic ring which may have a substituent, LB 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group.

[0045] According to a ninth aspect of the present invention, the electrophotographic photoreceptor of the eighth aspect satisfies 0.5≤(Mmax−Mmin) / Mw≤4.5.

[0046] According to a tenth aspect of the present invention, in the electrophotographic photoreceptor of the eighth or ninth aspect, 80,000≦Mw≦150,000 is satisfied.

[0047] According to the eleventh aspect of the present invention, in the electrophotographic photoreceptor according to any one of the eighth to tenth aspects, the dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4).

[0048] Formula (A1)

[0049] Formula (A2)

[0050] Formula (A3)

[0051] Formula (A4)

[0052] 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.

[0053] In formula (A2), n 201 and n 202 are each independently an integer of 0 or more and 4 or less, n 201 Ra 201 and n 202 Ra 202Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0054] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, 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.

[0055] 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.

[0056] According to a twelfth aspect of the present invention, in the electrophotographic photoreceptor according to the eleventh aspect, the dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4).

[0057] According to the thirteenth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the eighth to twelfth aspects, the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7) and a diol unit (B8) represented by formula (B8).

[0058] Formula (B1) Formula (B2) Formula (B3)

[0059] Formula (B4)

[0060] Formula (B5)

[0061] Formula (B6)

[0062] Formula (B7)

[0063] Formula (B8)

[0064] In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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.

[0065] In formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less 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.

[0066] 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.

[0067] In formula (B4), Rb 104 and Rb 204 are 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.

[0068] 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 205is 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.

[0069] 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.

[0070] In formula (B7), Rb 407 , 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.

[0071] 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.

[0072] According to a fourteenth aspect of the present invention, in the electrophotographic photoreceptor of the thirteenth aspect, the diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6).

[0073] According to a fifteenth aspect of the present invention, there is provided a process cartridge including the electrophotographic photoreceptor according to any one of the first to fourteenth aspects, wherein the process cartridge is attachable to and detachable from an image forming apparatus.

[0074] According to the sixteenth embodiment of the present invention, an image forming device is provided, which comprises: the electronic photographic photoreceptor of any one of the first to fourteenth embodiments; a charging device, which charges the surface of the electronic photographic photoreceptor; an electrostatic latent image forming device, which forms an electrostatic latent image on the surface of the charged electronic photographic photoreceptor; a developing device, which develops the electrostatic latent image formed on the surface of the electronic photographic photoreceptor by a developer containing a colorant to form a colorant image; and a transfer device, which transfers the colorant image to the surface of a recording medium.

[0075] (Effect)

[0076] According to the first, fourth, fifth, sixth or seventh scheme, an electronic photographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photoreceptor having a laminated photosensitive layer and a charge transport layer containing a polyester resin (1) having an Mw of less than 50,000 or more than 200,000 or (Mmax-Mmin) / Mw of less than 0.4 or more than 5.0, and is less likely to produce image defects even when dropped in a high temperature and high humidity environment, and is less likely to produce image defects even when left in a high temperature and high humidity environment for a long time.

[0077] According to the second embodiment, an electrophotographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electrophotographic photoreceptor having a laminated photosensitive layer and a charge transport layer in which the (Mmax-Mmin) / Mw of the polyester resin (1) is less than 0.5 or exceeds 4.5, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long period of time.

[0078] According to the third scheme, an electronic photographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photoreceptor having a laminated photosensitive layer and a charge transport layer containing a polyester resin (1) with an Mw of less than 80,000 or more than 150,000, and is less likely to produce image defects even when dropped in a high temperature and high humidity environment, and is less likely to produce image defects even when left in a high temperature and high humidity environment for a long period of time.

[0079] According to the eighth, eleventh, twelfth, thirteenth or fourteenth scheme, an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared with an electronic photographic photosensitive body having a single-layer photosensitive layer and the Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 50,000 or exceeds 200,000, or (Mmax-Mmin) / Mw is less than 0.4 or exceeds 5.0, and is not likely to produce image defects even if dropped in a high temperature and high humidity environment, and is not likely to produce image defects even if left in a high temperature and high humidity environment for a long time.

[0080] According to the ninth scheme, an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photosensitive body having a single-layer photosensitive layer and in which the (Mmax-Mmin) / Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 0.5 or exceeds 4.5, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long time.

[0081] According to the tenth scheme, an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photosensitive body having a single-layer photosensitive layer and in which the Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 80,000 or exceeds 150,000, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long time.

[0082] According to the fifteenth scheme, a processing box is provided, which has an electronic photographic photosensitive body with excellent uniformity of surface potential distribution, and is not prone to image defects even if dropped in a high temperature and high humidity environment, and is not prone to image defects even if left in a high temperature and high humidity environment for a long time.

[0083] According to the sixteenth scheme, an image forming device is provided, which has an electronic photographic photosensitive body with excellent uniformity of surface potential distribution, which is not prone to image defects even if dropped in a high temperature and high humidity environment, and is not prone to image defects even if left in a high temperature and high humidity environment for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 This is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the first embodiment.

[0085] Figure 2 This is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the second embodiment.

[0086] Figure 3 This is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0087] Figure 4 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0088] Hereinafter, embodiments of the present invention will be described. These descriptions and examples are provided to illustrate the embodiments and do not limit the scope of the embodiments.

[0089] 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.

[0090] In the numerical ranges described in the present invention, the upper limit or lower limit of one numerical range may be replaced by the upper limit or lower limit of another numerical range described in the present invention. In addition, in the numerical ranges described in the present invention, the upper limit or lower limit of the numerical range may be replaced by the values shown in the examples.

[0091] In the present invention, "A and / or B" has the same meaning as "at least one of A and B." That is, "A and / or B" may mean only A, only B, or a combination of A and B.

[0092] In the present invention, the term "process" refers not only to an independent process but also to a process that cannot be clearly distinguished from other processes as long as the purpose of the process can be achieved.

[0093] In the present invention, when the embodiments are described with reference to the drawings, the structure of the embodiment is not limited to the structure shown in the drawings. In addition, the sizes of the components in each figure are conceptual, and the relative relationship between the sizes of the components is not limited to this.

[0094] In the present invention, each component may contain multiple corresponding substances. In the present invention, when referring to the amount of each component in the composition, when multiple substances corresponding to each component are present in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition.

[0095] 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, the particle size of each component refers to the value for the mixture of the multiple types of particles present in the composition unless otherwise specified.

[0096] In the present invention, unless otherwise specified, alkyl groups and alkylene groups include linear, branched, and cyclic groups.

[0097] 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.

[0098] In the present invention, when a compound is represented by a structural formula, the symbols (C and H) representing carbon atoms and hydrogen atoms in a hydrocarbon group and / or hydrocarbon chain may be omitted.

[0099] In the present invention, the "structural unit" of a copolymer or resin has the same meaning as a monomer unit.

[0100] <Electrophotographic Photoreceptor>

[0101] The present invention provides a first embodiment and a second embodiment as an electrophotographic photoreceptor (hereinafter also referred to as a “photoreceptor”).

[0102] The photoreceptor according to the first embodiment includes a conductive substrate and a laminated photosensitive layer disposed on the conductive substrate and having a charge generating layer and a charge transporting layer.

[0103] The photoreceptor of the first embodiment may further include other layers (eg, an undercoat layer and an intermediate layer). In the photoreceptor of the first embodiment, the charge transport layer is preferably a surface layer.

[0104] The photoreceptor according to the second embodiment includes a conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate.

[0105] The photoreceptor of the second embodiment may further include other layers (eg, an undercoat layer and an intermediate layer). In the photoreceptor of the second embodiment, the single-layer photosensitive layer is preferably the surface layer.

[0106] Figure 1 This is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to the first embodiment. Figure 1 The photoreceptor 10A shown has a laminated photosensitive layer. Photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1. The charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called functionally separated photosensitive layer). Photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3. The undercoat layer 2 may or may not be present.

[0107] Figure 2 This is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to the second embodiment. Figure 2 The photoreceptor 10B shown has a single-layer photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are sequentially laminated on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5. The undercoat layer 2 may or may not be present.

[0108] In the photosensitive body of the first embodiment, the charge transport layer of the laminated photosensitive layer contains a charge transport material and a polyester resin (1), and the molecular weight distribution curve of the polyester resin (1) contained in the charge transport layer has at least two peaks. When the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the charge transport layer is set to Mw, 50,000≤Mw≤200,000 and 0.4≤(Mmax-Mmin) / Mw≤5.0 are satisfied.

[0109] In the photosensitive body of the second embodiment, the single-layer photosensitive layer contains a charge transport material and a polyester resin (1), and the molecular weight distribution curve of the polyester resin (1) contained in the single-layer photosensitive layer has at least two peaks. When the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the single-layer photosensitive layer is set to Mw, 50,000 ≤ Mw ≤ 200,000, and 0.4 ≤ (Mmax-Mmin) / Mw ≤ 5.0 are satisfied.

[0110] Hereinafter, when describing matters common to the first and second embodiments, the two embodiments will be collectively referred to as the present embodiment. When describing matters common to the charge transport layer and the single-layer photosensitive layer, the two layers will be collectively referred to as the photosensitive layer.

[0111] The photosensitive layer of the photoreceptor of this embodiment contains a polyester resin (1). The polyester resin (1) has aromatic rings stacked together to bond resin molecules to each other by intermolecular forces, thereby improving the wear resistance of the photosensitive layer.

[0112] The molecular weight distribution curve of the polyester resin (1) contained in the photosensitive layer of the photosensitive body of this embodiment has at least two peaks. When the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the photosensitive layer is set to Mw, 50,000≤Mw≤200,000 and 0.4≤(Mmax-Mmin) / Mw≤5.0 are satisfied.

[0113] The photosensitive body of this embodiment has the above-mentioned structure, so the potential distribution on the surface of the photosensitive body is excellent in uniformity, and image defects are not easily generated even if it is dropped in a high temperature and high humidity environment, and image defects are not easily generated even if it is left in a high temperature and high humidity environment for a long time.

[0114] The relatively low molecular weight polyester resin (1) is easily mixed with a charge transport material when preparing a coating solution for forming a photosensitive layer. Using a relatively low molecular weight polyester resin (1) in forming the photosensitive layer improves the dispersibility of the charge transport material in the photosensitive layer. As a result, the potential distribution on the surface of the photoreceptor is more uniform.

[0115] The photosensitive layer containing a relatively high molecular weight polyester resin (1) is not easy to soften even in a high temperature and high humidity environment (for example, a temperature of 40°C and a relative humidity of 85%). Therefore, it is not easy to produce image defects even if it is dropped in a high temperature and high humidity environment, and it is not easy to produce image defects even if it is left in a high temperature and high humidity environment for a long time.

[0116] The photosensitive layer of the photoreceptor of this embodiment produces the above-mentioned effects by containing both the relatively low molecular weight polyester resin (1) and the relatively high molecular weight polyester resin (1).

[0117] The molecular weight distribution curve of the polyester resin (1) contained in the photosensitive layer has at least two peaks. A polyester resin (1) having only one peak in the molecular weight distribution curve is not easy to achieve both "uniformity of potential distribution" and "image quality after dropping and after storage in a high-temperature and high-humidity environment."

[0118] When the Mw of the polyester resin (1) contained in the photosensitive layer is less than 50,000, the film tends to soften and flow at high temperatures, and the image quality deteriorates after being dropped or stored in a high-temperature, high-humidity environment. From the viewpoint of suppressing this phenomenon, the Mw of the polyester resin (1) contained in the photosensitive layer is 50,000 or more, preferably 80,000 or more, and more preferably 90,000 or more.

[0119] When the Mw of the polyester resin (1) contained in the photosensitive layer exceeds 200,000, the dispersibility of the charge transport material decreases, and the uniformity of the potential distribution decreases. From the viewpoint of suppressing this phenomenon, the Mw of the polyester resin (1) contained in the photosensitive layer is 200,000 or less, preferably 150,000 or less, and more preferably 130,000 or less.

[0120] If the (Mmax-Mmin) / Mw ratio of the polyester resin (1) contained in the photosensitive layer is less than 0.4, it is difficult for the low molecular weight component and the high molecular weight component to exert their respective preferred functions, and it is difficult to achieve both "uniformity of potential distribution" and "image quality after dropping and after storage in a high temperature and high humidity environment." From the viewpoint of achieving both "uniformity of potential distribution" and "image quality after dropping and after storage in a high temperature and high humidity environment," the (Mmax-Mmin) / Mw ratio of the polyester resin (1) contained in the photosensitive layer is 0.4 or more, preferably 0.5 or more, and more preferably 0.6 or more.

[0121] When the (Mmax-Mmin) / Mw ratio of the polyester resin (1) contained in the photosensitive layer exceeds 5.0, the disadvantages of the low molecular weight component and the high molecular weight component (low molecular weight component: easy to soften and flow, high molecular weight component: low dispersibility of the charge transport material) are emphasized, making it difficult to achieve both "uniformity of potential distribution" and "image quality after dropping and after storage in a high temperature and high humidity environment". From the viewpoint of achieving both "uniformity of potential distribution" and "image quality after dropping and after storage in a high temperature and high humidity environment", the (Mmax-Mmin) / Mw ratio of the polyester resin (1) contained in the photosensitive layer is 5.0 or less, preferably 4.5 or less, and more preferably 4.0 or less.

[0122] In this embodiment, the method for determining the molecular weight distribution curve, Mmin, Mmax and weight average molecular weight Mw of the polyester resin (1) contained in the photosensitive layer (a charge transport layer of a laminated photosensitive layer in the first embodiment and a single-layer photosensitive layer in the second embodiment) is as follows.

[0123] The photoreceptor is immersed in various solvents (which may be mixed solvents) to determine the solvent in which the photosensitive layer is dissolved. The photoreceptor is immersed in the solvent in which the photosensitive layer is dissolved to extract the constituent materials of the photosensitive layer. The solution from which the constituent materials of the photosensitive layer are extracted is added dropwise to a poor solvent for the polyester resin (1) (e.g., a non-polar solvent such as hexane, toluene, or a lower alcohol such as methanol, isopropyl alcohol. The poor solvent may be a mixed solvent) to reprecipitate the resin. The reprecipitation process is repeated twice as needed, and the reprecipitate is vacuum-dried to obtain the polyester resin (1).

[0124] The molecular weight of the polyester resin (1) obtained by the above treatment is measured by GPC (gel permeation chromatography). The GPC apparatus is, for example, HLC-8120 (Tosoh Corporation), the chromatographic column is, for example, TSKgel GMHHR-M+TSKgel GMHHR-M (7.8 mm I.D. × 30 cm) (Tosoh Corporation), and the solvent is tetrahydrofuran. Molecular weight calibration is performed using a monodisperse polystyrene standard sample, and the molecular weight Mmin of the maximum point of the minimum molecular weight peak, the molecular weight Mmax of the maximum point of the maximum molecular weight peak, and the weight-average molecular weight Mw are determined.

[0125] The molecular weight distribution curve of the polyester resin (1) contained in the photosensitive layer can have at least two peaks by mixing two or more polyester resins (1) having different weight-average molecular weights and using the mixed polyester resin (1) to form the photosensitive layer. The two or more polyester resins (1) mixed may have the same or different types of structural units.

[0126] When the mixed polyester resin (1) is set as resin a, resin b, resin c, ..., resin n, the weight average molecular weight of each is set as Mw(a), Mw(b), Mw(c), ..., Mw(n), and the mass ratio of each is set as W(a), W(b), W(c), ..., W(n), the weight average molecular weight Mw(Mix) of the mixed polyester resin (1) is Mw(Mix) = Σ(Mw(n) × W(n)).

[0127] When two or more polyester resins (1) having different weight average molecular weights are mixed, they are mixed so that Mw(Mix) satisfies the relationship of 50,000 ≤ Mw(Mix) ≤ 200,000.

[0128] In addition, when two or more polyester resins (1) having different weight-average molecular weights are mixed, they are mixed in such a manner that the difference ΔMw between the minimum and maximum values among Mw(a), Mw(b), Mw(c), ..., Mw(n) and Mw(Mix) satisfy the relationship 0.4×Mw(Mix)≤ΔMw≤5.0×Mw(Mix).

[0129] In the above, the two or more polyester resins (1) mixed may be the same or different in the type of structural unit. From the viewpoint of improving the uniformity of dispersion of the charge transport material in the photosensitive layer, it is preferred that the two or more polyester resins (1) mixed be the same in the type of structural unit. In other words, it is preferred that the photosensitive layer contain one type of polyester resin (1) in terms of the type of structural unit.

[0130] Hereinafter, the polyester resin (1) contained in the photosensitive layer and each layer of the photoreceptor will be described in detail.

[0131] [Polyester resin (1)]

[0132] The photosensitive layer contains a polyester resin (1) having at least a dicarboxylic acid unit (A) and a diol unit (B) as a binder resin. The polyester resin (1) may contain other dicarboxylic acid units in addition to the dicarboxylic acid unit (A). The polyester resin (1) may contain other diol units in addition to the diol unit (B).

[0133] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0134] Formula (A)

[0135] 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 0, 1, or 2.

[0136] ArA1 The aromatic ring may be a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and a benzene ring and a naphthalene ring are preferred.

[0137] Ar A1 The hydrogen atoms on the aromatic ring can be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. A1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0138] Ar A2 The aromatic ring may be a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and a benzene ring and a naphthalene ring are preferred.

[0139] Ar A2 The hydrogen atoms on the aromatic ring can be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. A2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0140] 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, 1 and Ra 2 They may be bonded to form a cyclic alkyl group.

[0141] Ra 1 and Ra 2 The alkyl group having 1 to 10 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0142] Ra 1 and Ra 2 The aryl group having 6 or more and 12 or less carbon atoms may be either a monocyclic ring or a polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 or more and 10 or less, and more preferably 6.

[0143] Ra 1and 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.

[0144] Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic ring or a polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

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

[0146] Formula (A1)

[0147] 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.

[0148] n 101 It is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0149] Formula (A2)

[0150] In formula (A2), n 201 and n 202 are each independently an integer of 0 or more and 4 or less, 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.

[0151] n 201 It is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0152] n 202 It is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0153] Formula (A3)

[0154] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, 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.

[0155] n 301 It is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0156] n 302 It is preferably 0, 1 or 2, more preferably 0 or 1, and further preferably 0.

[0157] Formula (A4)

[0158] 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.

[0159] n 401 It is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0160] Ra of formula (A1) 101 , Ra of formula (A2) 201 and Ra 202 , Ra in formula (A3) 301 and Ra 302 And Ra of formula (A4) 401 The specific method and preferred method are the same, therefore, Ra 101 、Ra 201 、Ra 202 、Ra 301 、Ra 302 and Ra 401 They are collectively referred to as "Ra" for explanation.

[0161] The alkyl group having 1 to 10 carbon atoms in 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.

[0162] 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.

[0163] 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.

[0164] 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 formed by linking these monocyclic alkyl groups.

[0165] The aryl group having 6 to 12 carbon atoms in Ra may be either monocyclic or polycyclic. The aryl group preferably has 6 to 10 carbon atoms, more preferably 6 carbon atoms.

[0166] Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0167] The alkyl group in the alkoxy group having 1 to 6 carbon atoms represented by Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0168] 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-pentoxy group, and an n-hexoxy group.

[0169] 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.

[0170] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0171] Hereinafter, dicarboxylic acid units (A1-1) to (A1-9) are shown as specific examples of the dicarboxylic acid unit (A1).

[0172] The dicarboxylic acid unit (A1) is not limited thereto.

[0173]

[0174] Hereinafter, dicarboxylic acid units (A2-1) to (A2-3) are shown as specific examples of the dicarboxylic acid unit (A2).

[0175] The dicarboxylic acid unit (A2) is not limited thereto.

[0176]

[0177] Hereinafter, dicarboxylic acid units (A3-1) to (A3-2) are shown as specific examples of the dicarboxylic acid unit (A3).

[0178] The dicarboxylic acid unit (A3) is not limited thereto.

[0179]

[0180] Hereinafter, dicarboxylic acid units (A4-1) to (A4-3) are shown as specific examples of the dicarboxylic acid unit (A4).

[0181] The dicarboxylic acid unit (A4) is not limited thereto.

[0182]

[0183] 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), and further preferably contains at least (A2-3).

[0184] The mass ratio of the total of the dicarboxylic acid units (A1) to (A4) in the polyester resin (1) is preferably 15% by mass or more and 60% by mass or less.

[0185] When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 15% by 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 more preferably 20% by mass or more, and even more preferably 25% by mass or more.

[0186] When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 60% by 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 more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0187] The dicarboxylic acid units (A1) to (A4) contained in the polyester resin (1) may be one type or two or more types.

[0188] Examples of the other dicarboxylic acid units (A) other than the dicarboxylic acid units (A1) to (A4) include aliphatic dicarboxylic acid units (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and these lower (e.g., having 1 to 5 carbon atoms) alkyl ester units. The polyester resin (1) may contain one or more of these dicarboxylic acid units.

[0189] The dicarboxylic acid units (A) contained in the polyester resin (1) may be one type or two or more types.

[0190] The diol unit (B) is a structural unit represented by the following formula (B).

[0191] Formula (B)

[0192] 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group.

[0193] Ar B1 The aromatic ring may be a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and a benzene ring and a naphthalene ring are preferred.

[0194] Ar B1 The hydrogen atoms on the aromatic ring can be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. B1When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0195] Ar B2 The aromatic ring may be a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and a benzene ring and a naphthalene ring are preferred.

[0196] Ar B2 The hydrogen atoms on the aromatic ring can be substituted by alkyl, aryl, aralkyl, alkoxy, aryloxy, halogen atoms, etc. B2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0197] Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be any of linear, branched, and 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.

[0198] Rb 1 and Rb 2 The aryl group having 6 or more and 12 or less carbon atoms may be either a monocyclic ring or a polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 or more and 10 or less, and more preferably 6.

[0199] Rb 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.

[0200] Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic ring or a polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0201] The diol unit (B) preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8).

[0202] The diol unit (B) more preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), and a diol unit (B6) represented by the formula (B6).

[0203] It is more preferred that the diol unit (B1) be selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B5) represented by the following formula (B5), and a diol unit (B6) represented by the following formula (B6).

[0204] More preferably, it contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), and a diol unit (B6) represented by the following formula (B6).

[0205] Most preferably, it contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1) and a diol unit (B2) represented by the following formula (B2).

[0206] Formula (B1)

[0207] In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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.

[0208] Rb 101 The number of carbon atoms in the branched alkyl group having 4 or more and 20 or less is 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. 101Specific 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, tert-pentadecyl, etc.

[0209] Formula (B2)

[0210] In formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less 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.

[0211] Rb 102 The number of carbon atoms in the linear alkyl group having 4 or more and 20 or less is preferably 4 or more and 16 or less, more preferably 4 or more and 12 or less, and further 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.

[0212] Formula (B3)

[0213] 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.

[0214] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, more preferably 1. Specific examples of the group include a methyl group, an ethyl group, and an n-propyl group.

[0215] Rb 113 and Rb 213 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropyloxy, and cyclobutyloxy.

[0216] 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.

[0217] Formula (B4)

[0218] In formula (B4), Rb 104 and Rb 204 are 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.

[0219] Rb 104 The alkyl group having 1 or more and 3 or less carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms in the alkyl group is preferably 1 or 2, more preferably 1. 104 Specific examples of include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0220] Formula (B5)

[0221] 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.

[0222] Ar 105The aryl group having 6 or more and 12 or less carbon atoms may be either a monocyclic ring or a polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 or more and 10 or less, and more preferably 6.

[0223] Ar 105 The alkyl group in the aralkyl group having 7 or more and 20 or less carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms in the aralkyl group having 7 or more and 20 or less carbon atoms is preferably 1 or more and 4 or less, more preferably 1 or 3 or less, and further preferably 1 or 2. 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthracenylmethyl, and phenyl-cyclopentylmethyl.

[0224] Formula (B6)

[0225] 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.

[0226] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, more preferably 1. Specific examples of the group include a methyl group, an ethyl group, and an n-propyl group.

[0227] Rb 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of such groups include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropyloxy, and cyclobutyloxy.

[0228] As Rb116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0229] Formula (B7)

[0230] In formula (B7), Rb 407 , 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.

[0231] Formula (B8)

[0232] 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.

[0233] 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, therefore, Rb 201 , Rb 202 , Rb 204 and Rb 205 Collectively referred to as "Rb 200 " for explanation.

[0234] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, more preferably 1.

[0235] 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.

[0236] Rb in formula (B1) 401 , Rb of formula (B2) 402 , Rb of formula (B3) 403 , Rb of formula (B4) 404 , Rb in formula (B5) 405 , Rb in formula (B6) 406 , Rb in formula (B7) 407 And Rb in formula (B8)408 The specific method and preferred method are the same, therefore, Rb 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 Collectively referred to as "Rb 400 " for explanation.

[0237] Rb 400 The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1.

[0238] 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.

[0239] Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

[0240] Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0241] Rb 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.

[0242] 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-pentoxy group, and an n-hexoxy group.

[0243] 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.

[0244] Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0245] As Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0246] Rb in formula (B1) 501 , Rb of formula (B2) 502, Rb of formula (B3) 503 , Rb of formula (B4) 504 , Rb in formula (B5) 505 , Rb in formula (B6) 506 , Rb in formula (B7) 507 And Rb in formula (B8) 508 The specific method and preferred method are the same, therefore, Rb 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 Collectively referred to as "Rb 500 " for explanation.

[0247] Rb 500 The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1.

[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 a cyclopropyl group and a cyclobutyl group.

[0251] Rb 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.

[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-pentoxy group, and an n-hexoxy 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 a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0255] As Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0256] Rb in formula (B1) 801 , Rb of formula (B2) 802 , Rb of formula (B3) 803 , Rb of formula (B4) 804 , Rb in formula (B5) 805 , Rb in formula (B6) 806 , Rb in formula (B7) 807 And Rb in formula (B8) 808 The specific method and preferred method are the same, therefore, Rb 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 Collectively referred to as "Rb 800 " for explanation.

[0257] Rb 800 The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1.

[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 a cyclopropyl group and a cyclobutyl group.

[0261] Rb 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.

[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-pentoxy group, and an n-hexoxy 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 a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0265] As Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0266] Rb in formula (B1) 901 , Rb of formula (B2) 902 , Rb of formula (B3) 903 , Rb of formula (B4) 904 , Rb in formula (B5) 905 , Rb in formula (B6) 906 , Rb in formula (B7) 907 And Rb in formula (B8) 908 The specific method and preferred method are the same, therefore, Rb 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb 907 and Rb 908 Collectively referred to as "Rb 900 " for explanation.

[0267] Rb 900 The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1.

[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 a cyclopropyl group and a cyclobutyl group.

[0271] Rb 900The 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-pentoxy group, and an n-hexoxy 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 a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0275] As Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0276] 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.

[0277]

[0278] 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.

[0279]

[0280] Hereinafter, diol units (B3-1) to (B3-4) are shown as specific examples of the diol unit (B3), but the diol unit (B3) is not limited thereto.

[0281]

[0282] Hereinafter, diol units (B4-1) to (B4-7) are shown as specific examples of the diol unit (B4), but the diol unit (B4) is not limited thereto.

[0283]

[0284] Hereinafter, diol units (B5-1) to (B5-6) are shown as specific examples of the diol unit (B5), but the diol unit (B5) is not limited thereto.

[0285]

[0286] Hereinafter, diol units (B6-1) to (B6-4) are shown as specific examples of the diol unit (B6), but the diol unit (B6) is not limited thereto.

[0287]

[0288] 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.

[0289]

[0290] Hereinafter, diol units (B8-1) to (B8-3) are shown as specific examples of the diol unit (B8), but the diol unit (B8) is not limited thereto.

[0291]

[0292] The diol units (B) contained in the polyester resin (1) may be one type or two or more types.

[0293] The mass ratio of the diol unit (B) in the polyester resin (1) is preferably 25% by mass or more and 80% by mass or less.

[0294] When the mass ratio of the diol unit (B) is 25% by mass or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass ratio of the diol unit (B) is more preferably 30% by mass or more, and even more preferably 35% by mass or more.

[0295] When the mass ratio of the diol unit (B) is 80% by mass or less, solubility in the coating solution for forming the photosensitive layer can be maintained, thereby improving abrasion resistance. From this viewpoint, the mass ratio of the diol unit (B) is more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0296] Examples of other diol units other than the diol unit (B) include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more of these diol units.

[0297] The ends of the polyester resin (1) can be capped or modified by an end-capping agent or a molecular weight modifier used during production. Examples of the end-capping agent or molecular weight modifier include monophenols, monoacid chlorides, monoalcohols, and monocarboxylic acids.

[0298] 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.

[0299] Examples of the monobasic acid chloride include monofunctional acid halides such as benzoyl chloride, benzoyl chloride, methanesulfonyl chloride, phenylchloroformate, acetyl chloride, butyryl chloride, octanoyl chloride, benzenesulfonyl chloride, benzenesulfenyl chloride, sulfenyl chloride, phenylphosphonyl chloride, and substituted products thereof.

[0300] Examples of the monohydric alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, and phenylethanol.

[0301] 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.

[0302] When two or more polyester resins (1) having different weight-average molecular weights are mixed and the mixed polyester resins (1) are used to form a photosensitive layer, the weight-average molecular weight of each polyester resin (1) before mixing is preferably 30,000 or more and 300,000 or less, more preferably 40,000 or more and 250,000 or less, and even more preferably 50,000 or more and 200,000 or less.

[0303] The molecular weight of the polyester resin (1) is a molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography), using tetrahydrofuran as an eluent.

[0304] The polyester resin (1) can be 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. As methods for polycondensing monomers, interfacial polymerization, solution polymerization, melt polymerization, etc. can be cited. The interfacial polymerization method is a polymerization method for obtaining polyester by mixing a dibasic carboxylic acid halide dissolved in an organic solvent immiscible with water and a diol dissolved in an alkaline aqueous solution. As literature related to the interfacial polymerization method, WMEARECKSON, J.Poly.Sci., XL399, 1959, Japanese Patent Publication No. 40-1959, etc. can be cited. The interfacial polymerization method reacts faster than the solution polymerization method, and therefore, the hydrolysis of the dibasic carboxylic acid halide can be suppressed, and as a result, a high molecular weight polyester resin can be obtained.

[0305] [Conductive substrate]

[0306] Examples of the conductive substrate include metal plates, metal drums, and metal belts made of metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of the conductive substrate include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" means a volume resistivity of less than 1×10 13 Ω·cm.

[0307] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a centerline average roughness Ra of 0.04 μm or greater and 0.5 μm or less to suppress interference fringes generated when irradiated with a laser beam. When non-interference light is used as the light source, preventing coarsening of interference fringes is not particularly necessary, but it is more suitable for extending the life of the printer because it suppresses defects caused by unevenness on the conductive substrate surface.

[0308] Examples of roughening methods include wet honing 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.

[0309] As a roughening method, there is also a method in which, instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the particles dispersed in the layer roughen the surface.

[0310] The roughening treatment based on anodic oxidation is to carry out anodic oxidation in the electrolyte solution with the conductive substrate of metal (such as aluminum) as anode, thus forms the process of oxide film on the surface of conductive substrate.As electrolyte solution, for example, sulfuric acid solution, oxalic acid solution etc. can be enumerated.But the porous anodic oxide film formed by anodic oxidation has chemical activity in its original state, is easily contaminated, and the resistance change caused by environment is also large.Therefore, preferably porous anodic oxide film is carried out to block the micropore of oxide film by the volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel can be added) to change into the sealing treatment of more stable hydrated oxide.

[0311] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the thickness is within the above range, the barrier property against injection tends to be effective and the increase in residual potential due to repeated use tends to be suppressed.

[0312] The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.

[0313] The treatment based on the acidic treatment liquid is carried out, for example, in the following manner. First, an acidic treatment liquid containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. As the mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid, for example, phosphoric acid is in the range of 10 mass % or more and 11 mass % or less, chromic acid is in the range of 3 mass % or more and 5 mass % or less, hydrofluoric acid is in the range of 0.5 mass % or more and 2 mass % or less, and the overall concentration of these acids is in the range of 13.5 mass % or more and 18 mass % or less. The treatment temperature is preferably, for example, 42°C or more and 48°C or less. The film thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

[0314] The boehmite treatment is performed, for example, by immersing the substrate in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the substrate with heated steam at 90°C to 120°C for 5 to 60 minutes. The coating preferably has a thickness of 0.1 μm to 5 μm. The substrate may further be anodized using an electrolyte solution with low coating solubility, such as adipic acid, boric acid, a borate, a phosphate, a phthalate, a maleate, a benzoate, a tartrate, or a citrate.

[0315] [Undercoat]

[0316] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0317] Examples of inorganic particles include powder resistance (volume resistivity) 1×10 2 Ω·cm or more and 1×10 11 Inorganic particles with a particle size of Ω·cm or less.

[0318] Among these, examples of the inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0319] The specific surface area of the inorganic particles obtained by the BET method is, for example, 10 m 2 / g or above is sufficient.

[0320] The volume average particle diameter of the inorganic particles may be, for example, 50 nm to 2000 nm (preferably 60 nm to 1000 nm).

[0321] 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, relative to the binder resin.

[0322] The inorganic particles may be surface treated. Two or more inorganic particles having different surface treatments or different particle sizes may be mixed and used.

[0323] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

[0324] 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.

[0325] Silane coupling agents can be used in combination of two or more. For example, a silane coupling agent having an amino group and other silane coupling agents can be used in combination. 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., but are not limited thereto.

[0326] 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.

[0327] The treatment amount of the surface treatment agent is preferably 0.5% by mass or more and 10% by mass or less relative to the inorganic particles, for example.

[0328] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier-blocking properties, the undercoat layer preferably contains both inorganic particles and an electron-accepting compound (acceptor compound).

[0329] As electron-accepting compounds, for example, there can be mentioned: quinone compounds such as tetrachlorobenzoquinone and tetrabromobenzoquinone (Bromanil); tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-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; dibenzophenone compounds; and other electron-transporting substances.

[0330] In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferably used. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, etc. are preferably used, and specifically, for example, anthraquinone, alizarin, quinizarin, anthraquinone, purpurin and their derivatives are preferably used.

[0331] 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.

[0332] 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.

[0333] The dry method is, for example, a method in which an electron accepting compound or an electron accepting compound dissolved in an organic solvent is directly added dropwise while stirring the inorganic particles by a mixer having a large shear force, and the electron accepting compound is sprayed together with dry air or nitrogen to adhere to the surface of the inorganic particles. When the electron accepting compound is added dropwise or sprayed, it can be done 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 100°C or above. There is no particular limitation on the sintering temperature and time as long as the electrophotographic properties can be obtained.

[0334] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent by a blender, ultrasonic dispersant, sand mill, grinder, 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, distillation by filtration or distillation. After the solvent is removed, sintering may be performed at a temperature of 100°C or above. The sintering temperature and time are not particularly limited as long as the electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles can be removed before the electron-accepting compound is added. Examples thereof include a method of removing the water content in the solvent while stirring and heating, and a method of removing the water content by azeotropic reaction with the solvent.

[0335] 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 treatment with a surface treatment agent may be performed simultaneously.

[0336] The content of the electron-accepting compound may be, for example, 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less, relative to the inorganic particles.

[0337] Examples of the binder resin for the undercoat 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, phenolic 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.

[0338] Examples of the binder resin used for the undercoat layer include charge-transporting resins having charge-transporting groups and conductive resins (eg, polyaniline).

[0339] Among them, the binder resin for the lower coating layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and 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, polyurethane 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.

[0340] When two or more of these binder resins are used in combination, the mixing ratio is set as needed.

[0341] The undercoat layer may contain various additives in order to improve electrical characteristics, enhance environmental stability, and enhance image quality.

[0342] Examples of additives include known materials such as electron-transporting pigments such as polycyclic condensation pigments and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they can also be added to the undercoat layer as additives.

[0343] 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.

[0344] 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 octylate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium butoxide stearate, and zirconium butoxide isostearate.

[0345] 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 titanium lactate, titanium lactate, ethyl titanium lactate, triethanolamine titanium, and titanium polyhydroxystearate.

[0346] Examples of the aluminum chelate compound include aluminum isopropoxide, monobutoxyaluminum diisopropoxide, aluminum butoxide, diethylacetoacetate aluminum diisopropoxide, and tris(ethylacetoacetate)aluminum.

[0347] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0348] The Vickers hardness of the undercoat layer may be 35 or higher.

[0349] To suppress moiré images, the surface roughness (ten-point average roughness) of the undercoat layer may be adjusted to 1 / (4n) to 1 / 2 of the wavelength λ of the exposure laser used (n is the refractive index of the upper layer).

[0350] 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 polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the surface of the undercoat layer may be ground. Examples of the grinding method include polishing, sandblasting, wet honing, and grinding.

[0351] The undercoat layer can be formed without particular limitation and can be formed by a known formation method, for example, 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 needed.

[0352] Examples of the solvent used for preparing the coating liquid for forming the 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.

[0353] 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.

[0354] 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.

[0355] Examples of a method for applying the undercoat layer-forming coating liquid to the conductive substrate include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0356] The film thickness of the undercoat layer is set within the range of, for example, preferably 15 μm or more, more preferably 20 μm or more and 50 μm or less.

[0357] [Middle layer]

[0358] An intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

[0359] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins.

[0360] 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.

[0361] The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0362] Among these compounds, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

[0363] The formation of the intermediate layer is not particularly limited and can be performed by a known formation method, for example, by forming a coating film of an intermediate layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0364] As a coating method for forming the intermediate layer, a conventional method such as dip coating, push coating, wire bar coating, spray coating, blade coating, air knife coating, curtain coating, etc. can be used.

[0365] The thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm to 3 μm. The intermediate layer can be used as an undercoat layer.

[0366] [Charge Generation Layer]

[0367] The charge generating layer may be, for example, a layer containing a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. Vapor-deposited layers of charge generating material are suitable for use with incoherent light sources such as LEDs (Light Emitting Diodes) and organic EL (Electroluminescence) image arrays.

[0368] 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.

[0369] Among them, in order to cope with near-infrared laser exposure, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials. Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, oxytitanium phthalocyanine, etc. are more preferred.

[0370] On the other hand, in order to cope with near-ultraviolet laser exposure, preferred charge generating materials include fused-ring aromatic pigments such as dibromoanthraquinone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and disazo pigments.

[0371] The above-mentioned charge generation material can be used even when using an incoherent light source such as an LED or an organic EL array whose light emission center wavelength is from 450 nm to 780 nm.

[0372] In contrast, using n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments as charge-generating materials reduces the generation of dark current, and even in thin films, image defects known as black spots can be suppressed. The n-type is determined based on the polarity of the photocurrent flowing using the commonly used time-of-flight method, with materials that more readily carry electrons than holes being considered n-type.

[0373] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane.

[0374] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (a polycondensate 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, polyurethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. Here, "insulating property" refers to a volume resistivity of 1×10 13 Ω·cm or more.

[0375] These binder resins may be used alone or in combination of two or more.

[0376] The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10:1 to 1:10 in terms of mass ratio.

[0377] The charge generating layer may contain other known additives.

[0378] The charge generating layer can be formed without particular limitation and can be formed using known methods, for example, by forming a coating film of a charge generating layer-forming coating solution comprising the above-mentioned components added to a solvent, drying the coating film, and heating as needed. The charge generating layer can be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when using condensed-ring aromatic pigments or perylene pigments as the charge generating material.

[0379] Examples of solvents used to prepare 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, and toluene. These solvents may be used alone or in combination of two or more.

[0380] As a method for dispersing particles (e.g., charge generating material) in the charge generating layer-forming coating liquid, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, or a horizontal sand mill; or a media-free disperser such as a stirrer, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer can be used. Examples of high-pressure homogenizers include 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 fine flow channels under high pressure.

[0381] During 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, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0382] Examples of a method for applying the charge generating layer-forming coating liquid onto the undercoat layer (or the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0383] The film thickness of the charge generating layer is set, for example, preferably within the range of 0.1 μm to 5.0 μm, more preferably within the range of 0.2 μm to 2.0 μm.

[0384] [Charge transport layer]

[0385] The charge transport layer is a layer containing a charge transport material and a binder resin.

[0386] Examples of charge transport materials include electron-transporting compounds such as p-benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and vinyl compounds. Other examples of charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

[0387] As the charge transport material, a polymer charge transport material can be used. Examples of the polymer charge transport material include known compounds having charge transport properties such as poly-N-vinylcarbazole and polysilane, among which polyester-based polymer charge transport materials are preferred.

[0388] 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, triarylamine 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, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds and resins having groups derived from these substances. Specifically, the following can be cited: paragraphs 0078 to 0080 of Japanese Patent Application Laid-Open No. 2021-117377, paragraphs 0046 to 0048 of Japanese Patent Application Laid-Open No. 2019-035900, paragraphs 0052 to 0053 of Japanese Patent Application Laid-Open No. 2019-012141, paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-071565, and paragraphs 015 Compounds described in paragraphs 0101 to 0110 of Japanese Patent Application No. 223, paragraph 0116 of Japanese Patent Application Laid-Open No. 2013-097300, paragraphs 0309 to 0316 of International Publication No. 2019 / 070003, paragraphs 0103 to 0107 of Japanese Patent Application Laid-Open No. 2018-159087, and paragraphs 0102 to 0113 of Japanese Patent Application Laid-Open No. 2021-148818.

[0389] From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a compound (C1) represented by the following formula (C1), a compound (C2) represented by formula (C2), a compound (C3) represented by formula (C3) and a compound (C4) represented by formula (C4).

[0390] Formula (C1)

[0391] In formula (C1), Ar T1 、Ar T2 and Ar T3 are independently aryl, -C6H 4- C(R T4 )=C(R T5 )(R T6 ) or -C6H 4- CH=CH-CH=C(R T7 )(R T8 ). R T4 、R T5 、R T6 、R T7 and R T8 are independently hydrogen, alkyl or aryl. T5 and R T6 When the aryl groups are aryl groups, the aryl groups can be connected to each other through -C(R 51 )(R 52 )-and / or-C(R 61 )=C(R 62 )-divalent group connected. R 51 、R 52 、R 61 and R 62 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0392] 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.

[0393] From the viewpoint of charge mobility, the compound (C1) preferably has at least one aryl group or -C6H 4- CH=CH-CH=C(R T7 )(R T8 ), more preferably a compound (C'1) represented by the following formula (C'1).

[0394] Formula (C'1)

[0395]

[0396] In formula (C'1), R T111 、R T112 、R T121 、R T122 、R T131 and R T132Each independently represents a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0397] Formula (C2)

[0398] 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 with 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 ). R T21 、R T22 、R T23 、R T24 and R T25 R are independently a hydrogen atom, an alkyl group or an aryl group. T221 and R T222 Each of Tm1, Tm2, Tn1 and Tn2 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.

[0399] 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.

[0400] As compound (C2), it is preferable that it 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.

[0401] Formula (C3)

[0402]

[0403] In formula (C3), R T301 、R T302 、RT311 and R T312 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, a -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ). R T31 、R T32 、R T33 、R T34 and R T35 R are independently a hydrogen atom, an alkyl group or an aryl group. T321 、R T322 and R T331 Each of To1, To2, Tp1, Tp2, Tq1, Tq2 and Tr1 is independently 0, 1 or 2.

[0404] 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.

[0405] Formula (C4)

[0406] In formula (C4), R T401 、R T402 、R T411 and R T412 are each independently a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, a -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ). R T41 、R T42 、R T43 、R T44 and R T45 R are independently a hydrogen atom, an alkyl group or an aryl group. T421 、R T422 and R T431Each 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. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2, and Tv1 are each independently 0, 1, or 2.

[0407] 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.

[0408] The content of the charge transport material contained in the charge transport layer is preferably 20% by mass or more and 70% by mass or less, more preferably 25% by mass or more and 65% by mass or less, and further preferably 30% by mass or more and 60% by mass or less, relative to the total mass of the charge transport layer.

[0409] The charge transport layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the charge transport layer is preferably 30% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, and particularly preferably 55% by mass or more. When the polyester resin (1) is used in combination with another resin, the other resin is preferably a polycarbonate resin.

[0410] The charge transport layer may contain other binder resins other than the polyester resin (1). Examples of other binder resins include polyester resins other than the polyester resin (1), polycarbonate 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, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinyl carbazole, and polysilane. These binder resins may be used alone or in combination of two or more.

[0411] The charge transport layer may contain other known additives, such as antioxidants, leveling agents, defoaming agents, fillers, and viscosity modifiers.

[0412] The charge transport layer can be formed without particular limitation and can be formed by a known method, for example, by forming a coating film of a charge transport layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0413] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and dichloroethane; and cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents can be used alone or in combination of two or more.

[0414] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0415] The film thickness of the charge transport layer is, for example, greater than 5 μm and less than 50 μm. From the viewpoint of the photosensitivity and wear life of the photoreceptor, it is preferably greater than 20 μm, more preferably greater than 22 μm, and further preferably greater than 25 μm. From the viewpoint of residual potential, it is preferably less than 50 μm, more preferably less than 47 μm, and further preferably less than 45 μm.

[0416] [Single-layer photosensitive layer]

[0417] The single-layer photosensitive layer (charge generation / charge transport layer) contains a charge generation material, a charge transport material, a binder resin, and, if necessary, other additives. These materials are the same as those described for the charge generation layer and the charge transport layer.

[0418] The single-layer photosensitive layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the single-layer photosensitive layer is preferably 30% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, and particularly preferably 55% by mass or more. When the polyester resin (1) is used in combination with another resin, the other resin is preferably a polycarbonate resin.

[0419] The content of the charge generating material in the single-layer photosensitive layer may be 0.1% by mass or more and 10% by mass or less, and preferably 0.8% by mass or more and 5% by mass or less, based on the total mass of the single-layer photosensitive layer.

[0420] The content of the charge transport material contained in the single-layer photosensitive layer is preferably 25% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 65% by mass or less, and further preferably 40% by mass or more and 60% by mass or less relative to the total mass of the single-layer photosensitive layer.

[0421] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer or the charge transporting layer.

[0422] The film thickness of the single-layer photosensitive layer is, for example, greater than 5 μm and less than 50 μm. From the viewpoint of the photosensitivity and wear life of the photoreceptor, it is preferably greater than 10 μm, more preferably greater than 12 μm, and further preferably greater than 15 μm. From the viewpoint of residual potential, it is preferably less than 50 μm, more preferably less than 47 μm, further preferably less than 45 μm, and further preferably less than 40 μm.

[0423] [Protective layer]

[0424] A protective layer is provided on the photosensitive layer as needed. 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.

[0425] Therefore, the protective layer may be a layer composed of a cured film (crosslinked film). Examples of these layers include the layers described in the following 1) or 2).

[0426] 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 product of the reactive group-containing charge transport material)

[0427] 2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton and having reactive groups (i.e., a layer containing a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

[0428] Examples of the reactive group of the reactive group-containing charge transport material include: chain polymerizable groups, epoxy groups, -OH, -OR [wherein R represents an alkyl group], -NH2, -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, and Qn represents an integer of 1 to 3] and other known reactive groups.

[0429] The chain polymerizable group is not particularly limited as long as it is a functional group capable of free radical polymerization. For example, it is a functional group having at least one carbon double bond. Specifically, it includes a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl sulfide group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among these, a group containing at least one selected from a vinyl group, a phenylvinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof is preferred as the chain polymerizable group due to its excellent reactivity.

[0430] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors. Examples thereof include skeletons derived from nitrogen-containing hole transport compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, and conjugated with nitrogen atoms. Among these, a triarylamine skeleton is preferred.

[0431] 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.

[0432] The protective layer may contain other known additives.

[0433] The protective layer can be formed by any known method, for example, by forming a coating film of a protective layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and optionally performing a curing treatment such as heating.

[0434] Examples of solvents used to prepare the protective layer-forming coating liquid include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.

[0435] The protective layer-forming coating liquid may be a solvent-free coating liquid.

[0436] Examples of a method for applying the protective layer-forming coating liquid onto the photosensitive layer (eg, charge transport layer) include conventional methods such as dip coating, push coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0437] The film thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, more preferably within the range of 2 μm to 10 μm.

[0438] <Image Forming Apparatus, Process Cartridge>

[0439] The image forming apparatus of this 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 charged surface of the electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. Furthermore, the electrophotographic photoreceptor of this embodiment is used as the electrophotographic photoreceptor.

[0440] The image forming device of this embodiment is applicable to the following well-known image forming devices: a device equipped with a fixing device for fixing the colorant image transferred to the surface of a recording medium; a device of a direct transfer method for directly transferring the colorant image formed on the surface of an electronic photographic photosensitive body to a recording medium; a device of an intermediate transfer method for transferring the colorant image formed on the surface of an electronic photographic photosensitive body once to the surface of an intermediate transfer body, and for a second time transferring the colorant 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 an electronic photographic photosensitive body before charging after transferring the colorant image; a device equipped with an anti-static device for eliminating static electricity by irradiating the surface of an electronic photographic photosensitive body with anti-static light after transferring the colorant image and before charging; and a device equipped with an electronic photographic photosensitive body heating component for increasing the temperature of the electronic photographic photosensitive body and lowering the relative temperature, etc.

[0441] In the case of an intermediate transfer method device, the transfer device is applicable, for example, to a structure having the following devices: an intermediate transfer body on the surface of which the colorant image is transferred, a primary transfer device that transfers the colorant image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time, and a secondary transfer device that transfers the colorant image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time.

[0442] The image forming apparatus of the present embodiment may be any of a dry development system image forming apparatus and a wet development system (development system using a liquid developer) image forming apparatus.

[0443] In the image forming apparatus of this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor of this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may further comprise, for example, at least one member selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0444] An example of the image forming apparatus according to the present embodiment will be described below, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and descriptions of the other parts will be omitted.

[0445] Figure 3 This is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0446] like Figure 3 As shown, the image forming apparatus 100 of this embodiment includes a process cartridge 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 positioned so as to be able to expose the electrophotographic photoreceptor 7 through the opening of the process cartridge 300. The transfer device 40 is positioned so as to face the electrophotographic photoreceptor 7 across the intermediate transfer body 50, with the intermediate transfer body 50 being positioned so as to partially contact the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 further includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) constitute an example of a transfer device.

[0447] Figure 3 The process cartridge 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) within a housing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, which is arranged 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.

[0448] Figure 3 In the example shown, the image forming apparatus includes 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, which are arranged as needed.

[0449] Hereinafter, each structure of the image forming apparatus according to this embodiment will be described.

[0450] -Charging device-

[0451] As the charging device 8, for example, a contact-type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging hose, etc. can be used. Alternatively, a non-contact roller charger, a grid electrode charger using corona discharge, a corotron charger, or other known chargers can be used.

[0452] -Exposure device-

[0453] As the exposure device 9, for example, an optical system device that exposes a semiconductor laser beam, LED light, liquid crystal shutter light, or the like to a prescribed image form on the surface of the electrophotographic photoreceptor 7 can be cited. 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 having an oscillation wavelength of around 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 having an oscillation wavelength in the range of more than 400nm and less than 450nm can also be used. In addition, a surface-emitting laser source that can output multiple beams in order to form a color image is also effective.

[0454] -Developing device-

[0455] Examples of the developing device 11 include conventional developing devices that develop with or without contacting a developer. The developing device 11 is not particularly limited as long as it has the aforementioned functions, and may be selected based on the intended purpose. Examples include known developers that utilize a brush, roller, or the like to deposit a single-component developer or a two-component developer onto the electrophotographic photoreceptor 7. Of these, a developing device that utilizes a developing roller that holds the developer on its surface is preferred.

[0456] 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 use with known developers.

[0457] -Cleaning device-

[0458] 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 type or a development and cleaning concurrent type may be employed.

[0459] -Transfer device-

[0460] Examples of the transfer device 40 include known transfer chargers such as a contact transfer charger using a belt, roller, film, or rubber blade, a grid electrode transfer charger using corona discharge, and a corotron transfer charger.

[0461] -Intermediate transfer body-

[0462] As the intermediate transfer member 50, a belt-shaped intermediate transfer member (intermediate transfer belt) made of polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity can be used. In addition, as the form of the intermediate transfer member, a roller-shaped intermediate transfer member can also be used in addition to the belt-shaped intermediate transfer member.

[0463] Figure 4 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0464] Figure 4 The illustrated image forming apparatus 120 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged side by side on the intermediate transfer body 50, and a single electrophotographic photoreceptor is used for each color. Aside from the tandem design, the image forming apparatus 120 has the same structure as the image forming apparatus 100.

[0465] [Example]

[0466] Hereinafter, the disclosed embodiments will be described in detail using examples, but the disclosed embodiments are not limited to these examples.

[0467] In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0468] In the following description, unless otherwise specified, synthesis, treatment, production, etc. are performed at room temperature (25°C ± 3°C).

[0469] <Preparation of polyester resin>

[0470] In each of the Examples and Comparative Examples shown in Tables 1 and 2, at least two polyester resins having the same structural unit type and different weight-average molecular weights were synthesized and mixed to prepare the polyester resin for each example. In all polyester resin syntheses, polymerization was performed in the presence of 2,3,5-trimethylphenol, a terminal capping agent, to cap the resin terminals.

[0471] In Comparative Example S1 and Comparative Example T1, a monodispersed polyester resin was used.

[0472] Tables 1 and 2 show the units constituting the polyester resins.

[0473] A2-3 and the like described in Table 1 and Table 2 are specific examples of the dicarboxylic acid unit (A) already described.

[0474] B1-4 and the like described in Table 1 and Table 2 are specific examples of the diol unit (B) already described.

[0475] In Example S13, two dicarboxylic acid units (A) are used in the synthesis of the polyester resin, and the molar ratio of the two dicarboxylic acid units (A) is (A1-1):(A1-7)=1:1.

[0476] Example S22 uses two diol acid units (B) in the synthesis of polyester resin, and the molar ratio of the two diol units (B) is (B1-2):(B7-2)=2:3.

[0477] In Example S23, two dicarboxylic acid units (A) are used in the synthesis of the polyester resin, and the molar ratio of the two dicarboxylic acid units (A) is (A3-2):(A4-3)=4:1.

[0478] <Manufacturing of a Photoreceptor Having a Laminated Photosensitive Layer>

[0479] [Example S1]

[0480] -Formation of undercoat layer-

[0481] As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1.6 mm was prepared.

[0482] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 100 parts of silane (1,000 g, TAYCA Co., Ltd.) and 500 parts of toluene were stirred and mixed, and 1.3 parts of a silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was calcined at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0483] 110 parts of surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, 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. The solid content was then filtered off by vacuum filtration and dried at 60°C under reduced pressure to obtain alizarin-imparted zinc oxide.

[0484] 100 parts of a solution prepared by dissolving 60 parts of alizarin-imparted zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, trade name: SUMIDUR 3175, Sumitomo Bayer Urethane Co., Ltd.), and 15 parts of a butyral resin (trade name: S-LEC BM-1, Sekisui Chemical Co., Ltd.) in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone and dispersed for 2 hours using a sand mill with 1 mm diameter glass beads to obtain a dispersion. 0.005 parts of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: Tospearl 145, Momentive Performance Materials Japan LLC) were added to the dispersion as a catalyst to obtain a coating solution for forming an undercoat layer. The coating liquid for forming an undercoat layer was applied to the outer peripheral surface of the conductive substrate by dip coating, and dried and cured at 185° C. for 35 minutes to form an undercoat layer having an average thickness of 25 μm.

[0485] -Formation of Charge Generation Layer-

[0486] A mixture consisting 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 an X-ray diffraction spectrum using CuKα characteristic X-rays), 10 parts of a vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, Nippon Unicar Company Limited) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill for 4 hours using 1 mm diameter glass beads. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature (25°C±3°C) to form a charge generating layer with an average thickness of 0.25 μm.

[0487] -Formation of Charge Transport Layer-

[0488] ·Binder resin: 60 parts of polyester resin

[0489] Charge transport material: CTM-1 40 parts

[0490] 270 parts of tetrahydrofuran

[0491] 30 parts of toluene

[0492] Table 1 lists the structural units, weight-average molecular weight, and molecular weight distribution of the polyester resin used in this example.

[0493] The above materials were stirred and mixed to obtain a charge transport layer coating solution, which was dip-coated on the charge generating layer and dried at 145° C. for 30 minutes to form a charge transport layer with an average thickness of 40 μm.

[0494] [Examples S2 to S24 and Comparative Examples S1 to S5]

[0495] The same procedure as in Example S1 was carried out except that the type of the binder resin in the charge transport layer was changed to that described in Table 1, and respective photoreceptors were produced.

[0496] [Example S25]

[0497] A photoreceptor was prepared in the same manner as in Example S1 except that the binder resins in the charge transport layer were changed to 30 parts polyester resin and 30 parts polycarbonate resin. The structural units, weight average molecular weight, and molecular weight distribution of the polyester resin used in this example are shown in Table 1.

[0498] The polycarbonate resin used in this example is a polycarbonate resin composed of the following repeating units: This resin is referred to as polycarbonate resin (PC-1).

[0499]

[0500] [Examples S26 to S29]

[0501] The same procedure as in Example S1 was carried out except that the type of the binder resin and the type of the charge transport material in the charge transport layer were changed as shown in Table 1, and respective photoreceptors were produced.

[0502] In Example 28, 20 parts of CTM-1 and 20 parts of CTM-3 were used.

[0503] The chemical structures of charge transport materials CTM-1 to CTM-4 are shown below.

[0504]

[0505] <Manufacturing of a Photoreceptor Having a Single-Layer Photosensitive Layer>

[0506] [Example T1]

[0507] -Formation of undercoat layer-

[0508] As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1.6 mm was prepared.

[0509] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2100 parts of silane (1,000 g, TAYCA Co., Ltd.) and 500 parts of toluene were stirred and mixed, and 1.3 parts of a silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was calcined at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0510] 110 parts of surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, 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. The solid content was then filtered off by vacuum filtration and dried at 60°C under reduced pressure to obtain alizarin-imparted zinc oxide.

[0511] A solution of 60 parts of alizarin-imparted zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, trade name: SUMIDUR 3175, Sumitomo Bayer Polyurethanes Co., Ltd.), and 15 parts of a butyral resin (trade name: S-LEC BM-1, Sekisui Chemical Co., Ltd.) dissolved in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone and dispersed using 1 mm diameter glass beads in 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: Tospearl 145, Momentive Advanced Materials Japan Co., Ltd.) were added to the dispersion as catalysts to obtain a coating solution for forming an undercoat layer. This coating solution was applied to the outer surface of the conductive substrate by dip coating and dried and cured at 185°C for 35 minutes to form an undercoat layer with an average thickness of 25 μm.

[0512] -Formation of a single-layer photosensitive layer-

[0513] Binder resin: 52.75 parts polyester resin

[0514] Charge generating material: 1.25 parts of V-type hydroxygallium phthalocyanine

[0515] (The diffraction peaks are present at positions where the Bragg angles (2θ±0.2°) of the X-ray diffraction spectrum using CuKα characteristic X-rays are at least 7.3°, 16.0°, 24.9°, and 28.0°.)

[0516] Charge transport material: ETM-1 7.8 parts

[0517] Charge transport material: CTM-1 38.2 parts

[0518] (The mass ratio of ETM-1 to CTM-1 is 17:83)

[0519] 175 parts of tetrahydrofuran

[0520] 75 parts of toluene

[0521] Table 2 shows the structural units, weight average molecular weight, and molecular weight distribution of the polyester resin used in this example.

[0522] The above materials were mixed and dispersed using 1 mm diameter glass beads in a sand mill for 4 hours to obtain a photosensitive layer coating solution. This photosensitive layer coating solution was then dip-coated onto the undercoat layer and dried and cured at 110°C for 40 minutes to form a single-layer photosensitive layer with an average thickness of 34 μm.

[0523]

[0524] [Examples T2 to T11, T13, T14 and Comparative Examples T1 to T5]

[0525] The same procedure as in Example T1 was carried out except that the type of binder resin in the single-layer photosensitive layer was changed to the type listed in Table 2, and respective photoreceptors were produced.

[0526] [Example T12]

[0527] A photoreceptor was prepared in the same manner as in Example T1, except that the binder resin in the single-layer photosensitive layer was changed to 26.75 parts of a polyester resin and 26 parts of a polycarbonate resin. The structural units, weight-average molecular weight, and molecular weight distribution of the polyester resin used in this example are shown in Table 2. The polycarbonate resin used in this example was polycarbonate resin (PC-1).

[0528] <Performance Evaluation of Photoreceptor>

[0529] [Potential distribution]

[0530] The photoreceptors of each Example or Comparative Example were installed in an Apeos C7070 image forming apparatus (Fujifilm Business Innovation Co., Ltd.). To measure the surface potential of the photoreceptors, a probe connected to a surface potentiometer (Trek334, Trek Japan Co., Ltd.) was positioned 1 mm from the photoreceptor surface at the axial center of the photoreceptor. Charging and exposure conditions were adjusted in an environment with a temperature of 20°C and a relative humidity of 40% to achieve a surface potential of -650 V after charging and -300 V after exposure.

[0531] Probes connected to the surface potential meter were placed at 11 locations, one at the axial center of the photoreceptor and at positions 2 cm, 4 cm, 6 cm, 8 cm, and 10 cm from the axial center toward either end. The surface potential of the photoreceptor was measured at these 11 locations, and the difference between the maximum and minimum values was calculated. The difference was then classified as follows.

[0532] A+: The difference is less than 5V

[0533] A: The difference is more than 5V and less than 10V

[0534] B: The difference is more than 10V and less than 20V

[0535] C: The difference exceeds 20V

[0536] [Image quality after falling]

[0537] -Normal environment-

[0538] The following operations were performed in an environment with a temperature of 20° C. and a relative humidity of 40%.

[0539] The photosensitive body of each embodiment or each comparative example and other necessary components are combined to form Figure 3 The process cartridge 300 shown in FIG. To record the contact positions between the photoreceptor and the cleaning blade, oil-based ink is used to mark the contact positions at both ends of the photoreceptor in the axial direction. When an image is formed, the amount of toner deposited on the photoreceptor surface differs between the areas marked with oil-based ink and those not marked with oil-based ink, allowing identification of these locations.

[0540] Next, with the photoreceptor's axis oriented horizontally, the process cartridge was dropped from a height of 30 cm onto a concrete horizontal platform. The photoreceptor was rotated 90° in the circumferential direction (i.e., the position contacting the cleaning blade was moved 90° in the circumferential direction) four times.

[0541] Next, the process cartridge was mounted on the image forming apparatus Apeos C7070, and 10 black images having an image density (area coverage) of 30% were continuously output on A3-size plain paper.

[0542] Visually inspect 10 images. Observe the presence or absence of color density differences and image defects at the location corresponding to the point where the photoreceptor and cleaning blade would contact when the process cartridge is allowed to fall, compared to locations other than the location. The presence or absence of color density differences and image defects is categorized as follows.

[0543] A+: No image defects are visible. No color density differences are observed.

[0544] A: No image defects were observed. Slight color density differences were visible, but disappeared within 10 images.

[0545] B: Slight image defects are visible at various locations in the axial direction.

[0546] C: Obvious image defects can be seen on one axial surface.

[0547] -High temperature and high humidity-

[0548] The photosensitive body of each embodiment or each comparative example and other necessary components are combined to form Figure 3 The process cartridge 300 shown was marked with oil-based ink in the same manner as above and placed in an environment at a temperature of 40° C. and a relative humidity of 85% for three days.

[0549] Next, the same free fall test as above was performed in an environment of a temperature of 40° C. and a relative humidity of 85%.

[0550] Next, the process cartridge was left in an environment at a temperature of 20° C. and a relative humidity of 40% for 10 hours, and thereafter, the same image forming test as above was performed in an environment at a temperature of 20° C. and a relative humidity of 40%.

[0551] [Storage stability]

[0552] -Normal environment-

[0553] The following operations were performed in an environment with a temperature of 20° C. and a relative humidity of 40%.

[0554] The photosensitive body of each embodiment or each comparative example and other necessary components are combined to form Figure 3 The process cartridge 300 shown in FIG. A 1 cm square urethane sponge (3M Japan Co., Ltd. Scotch-Brite formed into a 1 cm cube) is held at the cleaning blade contact point at the axial center of the photoreceptor. To record this position, the cleaning blade contact points at both ends of the photoreceptor are marked with oil-based ink. When an image is formed on the photoreceptor surface, the amount of toner deposited differs between the areas marked with oil-based ink and those not marked with oil-based ink, allowing identification of these locations.

[0555] Next, while still holding the urethane sponge, the process box was placed in an environment at a temperature of 20° C. and a relative humidity of 40% for 3 days.

[0556] Next, the urethane sponge was removed from the process cartridge, and the process cartridge was mounted on the image forming apparatus Apeos C7070, and 10 black images with an image density (area coverage) of 30% were continuously output on A3-size plain paper.

[0557] Ten images were visually inspected. The presence or absence of color density differences and image defects was visually observed at locations corresponding to those in contact with the urethane sponge during the three-day storage period, compared to locations other than the urethane sponge. The presence or absence of color density differences and image defects was classified as follows.

[0558] A+: No image defects are visible. No color density differences are observed.

[0559] A: No image defects were observed. Slight color density differences were visible, but disappeared within 10 images.

[0560] B: Slight image defects are visible at various locations in the axial direction.

[0561] C: Obvious image defects can be seen on one axial surface.

[0562] -High temperature and high humidity-

[0563] The photosensitive body of each embodiment or each comparative example and other necessary components are combined to form Figure 3 The process cartridge 300 shown was placed in an environment of 40° C. and 85% relative humidity for 3 days while holding a urethane sponge in the same manner as described above.

[0564] Next, the urethane sponge was removed from the process cartridge, and the process cartridge was placed in an environment at a temperature of 20° C. and a relative humidity of 40% for 10 hours. Thereafter, the same image formation test as above was performed in an environment at a temperature of 20° C. and a relative humidity of 40%.

[0565] [Table 1]

[0566]

[0567] [Table 2]

[0568]

[0569] (Note) (((1)))

[0571] An electrophotographic photoreceptor comprising a conductive substrate and a laminated photosensitive layer disposed on the conductive substrate and having a charge generating layer and a charge transporting layer.

[0572] The charge transport layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B).

[0573] The molecular weight distribution curve of the polyester resin (1) contained in the charge transport layer has at least two peaks. When the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the charge transport layer is set to Mw, 50,000 ≤ Mw ≤ 200,000, and 0.4 ≤ (Mmax - Mmin) / Mw ≤ 5.0 are satisfied.

[0574] Formula (A)

[0575] Formula (B)

[0576] 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 0, 1, or 2.

[0577] 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group. (((2)))

[0579] The electrophotographic photoreceptor according to (((1))), wherein 0.5≤(Mmax-Mmin) / Mw≤4.5 is satisfied. (((3)))

[0581] The electrophotographic photoreceptor according to (((1))) or (((2))), wherein 80,000≦Mw≦150,000 is satisfied. (((4)))

[0583] The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein the dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4).

[0584] Formula (A1)

[0585] Formula (A2)

[0586] Formula (A3)

[0587] Formula (A4)

[0588] In formula (A1), n101 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.

[0589] In formula (A2), n 201 and n 202 are each independently an integer of 0 or more and 4 or less, 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.

[0590] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, 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.

[0591] 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. (((5)))

[0593] The electrophotographic photoreceptor according to (((4))), wherein the dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4). (((6)))

[0595] The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8).

[0596] Formula (B1)

[0597] Formula (B2)

[0598] Formula (B3)

[0599] Formula (B4)

[0600] Formula (B5)

[0601] Formula (B6)

[0602] Formula (B7)

[0603] Formula (B8)

[0604] In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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.

[0605] In formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less 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.

[0606] 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.

[0607] In formula (B4), Rb 104 and Rb 204 are 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.

[0608] 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.

[0609] 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.

[0610] In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907Each 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.

[0611] 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. (((7)))

[0613] The electrophotographic photoreceptor according to (((6))), wherein the diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6). (((8)))

[0615] An electrophotographic photoreceptor comprising a conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate.

[0616] The single-layer photosensitive layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B).

[0617] The molecular weight distribution curve of the polyester resin (1) contained in the single-layer photosensitive layer has at least two peaks. When the molecular weight of the maximum point of the peak with the smallest molecular weight is set to Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set to Mmax, and the weight-average molecular weight of the polyester resin (1) contained in the single-layer photosensitive layer is set to Mw, 50,000≤Mw≤200,000 and 0.4≤(Mmax-Mmin) / Mw≤5.0 are satisfied.

[0618] Formula (A)

[0619] Formula (B)

[0620] 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 0, 1, or 2.

[0621] 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(Rb1 )(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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group. (((9)))

[0623] The electrophotographic photoreceptor according to (((8))), wherein 0.5≤(Mmax-Mmin) / Mw≤4.5 is satisfied. (((10)))

[0625] The electrophotographic photoreceptor according to (((8))) or (((9))), wherein 80,000≦Mw≦150,000 is satisfied. (((11)))

[0627] The electrophotographic photoreceptor according to any one of (((8))) to (((10))), wherein the dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4).

[0628] Formula (A1)

[0629] Formula (A2)

[0630] Formula (A3)

[0631] Formula (A4)

[0632] 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.

[0633] In formula (A2), n 201 and n 202 are each independently an integer of 0 or more and 4 or less, n 201 Ra 201 and n 202 Ra202 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.

[0634] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, 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.

[0635] 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. (((12)))

[0637] The electrophotographic photoreceptor according to (((11))), wherein the dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4). (((13)))

[0639] An electrophotographic photoreceptor according to any one of (((8))) to (((12))), wherein the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8).

[0640] Formula (B1)

[0641] Formula (B2)

[0642] Formula (B3)

[0643] Formula (B4)

[0644] Formula (B5)

[0645] Formula (B6)

[0646] Formula (B7)

[0647] Formula (B8)

[0648] In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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.

[0649] In formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less 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.

[0650] 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.

[0651] In formula (B4), Rb 104 and Rb 204 are 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.

[0652] 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.

[0653] 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.

[0654] In formula (B7), Rb 407 , 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.

[0655] 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. (((14)))

[0657] The electrophotographic photoreceptor according to (((13))), wherein the diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6). (((15)))

[0659] A process cartridge comprising the electrophotographic photoreceptor described in any one of (((1))) to (((14))),

[0660] The process cartridge is attachable to and detachable from the image forming apparatus. (((16)))

[0662] An image forming apparatus comprising:

[0663] The electrophotographic photoreceptor according to any one of (((1))) to (((14)));

[0664] a charging device for charging the surface of the electrophotographic photoreceptor;

[0665] an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0666] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and

[0667] A transfer device transfers the toner image to a surface of a recording medium.

[0668] According to (((1))), (((4))), (((5))), (((6))) or (((7))), an electronic photographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photoreceptor having a laminated photosensitive layer and in which the Mw of the polyester resin (1) contained in the charge transport layer is less than 50,000 or exceeds 200,000, or (Mmax-Mmin) / Mw is less than 0.4 or exceeds 5.0, and is less likely to produce image defects even when dropped in a high temperature and high humidity environment, and is less likely to produce image defects even when left for a long period of time in a high temperature and high humidity environment.

[0669] According to (((2))), an electronic photographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photoreceptor having a laminated photosensitive layer and a charge transport layer in which the (Mmax-Mmin) / Mw of the polyester resin (1) is less than 0.5 or exceeds 4.5, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long period of time.

[0670] According to (((3))), an electronic photographic photoreceptor is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photoreceptor having a laminated photosensitive layer and a charge transport layer containing a polyester resin (1) with an Mw of less than 80,000 or more than 150,000, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long period of time.

[0671] According to (((8))), (((11))), (((12))), (((13))) or (((14))), an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared with an electronic photographic photosensitive body having a single-layer photosensitive layer and in which the Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 50,000 or exceeds 200,000, or (Mmax-Mmin) / Mw is less than 0.4 or exceeds 5.0, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long time.

[0672] According to (((9))), an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photosensitive body having a single-layer photosensitive layer and in which the (Mmax-Mmin) / Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 0.5 or exceeds 4.5, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long time.

[0673] According to (((10))), an electronic photographic photosensitive body is provided, which has excellent uniformity of surface potential distribution compared to an electronic photographic photosensitive body having a single-layer photosensitive layer and in which the Mw of the polyester resin (1) contained in the single-layer photosensitive layer is less than 80,000 or exceeds 150,000, and is less likely to produce image defects even when dropped in a high-temperature and high-humidity environment, and is less likely to produce image defects even when left in a high-temperature and high-humidity environment for a long time.

[0674] According to (((15))), a processing box is provided, which has an electronic photographic photosensitive body with excellent uniformity of surface potential distribution, and is not prone to image defects even if dropped in a high temperature and high humidity environment, and is not prone to image defects even if left for a long period of time in a high temperature and high humidity environment.

[0675] According to (((16))), an image forming device is provided, which has an electronic photographic photosensitive body with excellent uniformity of surface potential distribution, which is not prone to image defects even if dropped in a high temperature and high humidity environment, and which is not prone to image defects even if left for a long period of time in a high temperature and high humidity environment.

Claims

1. An electrophotographic photoreceptor, characterized in that A photosensitive layer having a conductive substrate and a charge generating layer and a charge transporting layer disposed on the conductive substrate. The charge transport layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). The molecular weight distribution curve of the polyester resin (1) contained in the charge transport layer has at least two peaks, and when the molecular weight of the maximum point of the peak with the smallest molecular weight is set as Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set as Mmax, and the weight average molecular weight of the polyester resin (1) contained in the charge transport layer is set as Mw, 50,000≤Mw≤200,000, and 0.4≤(Mmax-Mmin) / Mw≤5.0 is satisfied, 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group.

2. The electrophotographic photoreceptor according to claim 1, wherein Satisfies 0.5≤(Mmax-Mmin) / Mw≤4.

5.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein Meet 80,000≤Mw≤150,000.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein The dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). 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 or more and 4 or less, 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 or more and 4 or less, 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.

5. The electrophotographic photoreceptor according to claim 4, wherein The dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4).

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8), Formula (B1) Formula (B2) Formula (B3) Formula (B4) Formula (B5) Formula (B6) Formula (B7) Formula (B8) In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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 linear alkyl group having 4 or more and 20 or less 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 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.

7. The electrophotographic photoreceptor according to claim 6, wherein The diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6).

8. An electrophotographic photoreceptor, characterized in that A conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate. The single-layer photosensitive layer contains a charge transport material and a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). The molecular weight distribution curve of the polyester resin (1) contained in the single-layer photosensitive layer has at least two peaks, and when the molecular weight of the maximum point of the peak with the smallest molecular weight is set as Mmin, the molecular weight of the maximum point of the peak with the largest molecular weight is set as Mmax, and the weight average molecular weight of the polyester resin (1) contained in the single-layer photosensitive layer is set as Mw, it satisfies 50,000≤Mw≤200,000, and 0.4≤(Mmax-Mmin) / Mw≤5.0, 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, 1 and Rb 2 They may be bonded to form a cyclic alkyl group.

9. The electrophotographic photoreceptor according to claim 8, wherein Satisfies 0.5≤(Mmax-Mmin) / Mw≤4.

5.

10. The electrophotographic photoreceptor according to claim 8 or 9, wherein Meet 80,000≤Mw≤150,000.

11. The electrophotographic photoreceptor according to any one of claims 8 to 10, wherein The dicarboxylic acid unit (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by formula (A1), a dicarboxylic acid unit (A2) represented by formula (A2), a dicarboxylic acid unit (A3) represented by formula (A3), and a dicarboxylic acid unit (A4) represented by formula (A4). 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 or more and 4 or less, 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 or more and 4 or less, 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.

12. The electrophotographic photoreceptor according to claim 11, wherein The dicarboxylic acid unit (A) contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4).

13. The electrophotographic photoreceptor according to any one of claims 8 to 12, wherein The diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by formula (B1), a diol unit (B2) represented by formula (B2), a diol unit (B3) represented by formula (B3), a diol unit (B4) represented by formula (B4), a diol unit (B5) represented by formula (B5), a diol unit (B6) represented by formula (B6), a diol unit (B7) represented by formula (B7), and a diol unit (B8) represented by formula (B8), Formula (B1) Formula (B2) Formula (B3) Formula (B4) Formula (B5) Formula (B6) Formula (B7) Formula (B8) In formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less 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 linear alkyl group having 4 or more and 20 or less 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 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.

14. The electrophotographic photoreceptor according to claim 13, wherein The diol unit (B) contains at least one selected from the group consisting of the diol unit (B1), the diol unit (B2), the diol unit (B5), and the diol unit (B6).

15. A process cartridge, characterized in that: An electrophotographic photoreceptor according to any one of claims 1 to 14, The process cartridge is attachable to and detachable from the image forming apparatus.

16. An image forming apparatus, characterized in that: have: The electrophotographic photoreceptor according to any one of claims 1 to 14; 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 toner to form a toner image; and A transfer device transfers the toner image to a surface of a recording medium.

Images