Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus

Abstract

Provided is an electrophotographic photoreceptor capable of providing good electrical characteristics, in particular, residual potential characteristics, even when a compound having an electron-transporting structure is contained in a protective layer. As a novel electrophotographic photoreceptor, the electrophotographic photoreceptor has at least a photosensitive layer and a protective layer on a conductive support, in which the protective layer contains an electron-donating compound and preferably further contains an electron-transporting compound.

Description

Technical Field

[0001] The present invention relates to an electrophotographic photoreceptor used in a copying machine, a printer, etc., an electrophotographic photoreceptor cartridge using the electrophotographic photoreceptor, and an image forming apparatus. Background Art

[0002] In printers and copiers, when a charged organic photoconductor (OPC) drum is irradiated with light, the portion is de-charged to generate an electrostatic latent image, and toner is attached to the electrostatic latent image, thereby obtaining an image. In devices using such electrophotographic technology, the photoconductor is a core component.

[0003] This type of organic photoreceptor has a wide range of material choices and is easy to control the properties of the photoreceptor. Therefore, the "functional separation type photoreceptor" in which different compounds share the charge generation and transfer functions has become the mainstream. For example, there are known single-layer electrophotographic photoreceptors (hereinafter referred to as single-layer photoreceptors) having a charge generating material (CGM) and a charge transporting material (CTM) in the same layer, and stacked electrophotographic photoreceptors (hereinafter referred to as stacked photoreceptors) in which a charge generating layer containing a charge generating material (CGM) and a charge transporting layer containing a charge transporting material (CTM) are stacked. In addition, as charging methods for the photoreceptor, there can be cited: a negative charging method in which the surface of the photoreceptor is negatively charged and a positive charging method in which the surface of the photoreceptor is positively charged. Examples of the combination of the layer structure and charging method of photoreceptors currently in practical use include "negatively chargeable laminated photoreceptors" and "positively chargeable single-layer photoreceptors".

[0004] A "negatively charged stacked photosensitive body" generally has the following structure: a base coat layer (UCL) composed of a resin or the like is provided on a conductive substrate such as an aluminum tube, a charge generating layer (CGL) composed of a charge generating material (CGM) and a resin or the like is provided thereon, and further a charge transport layer (CTL) composed of a hole transport material (HTM) and a resin or the like is provided thereon.

[0005] On the other hand, a "positively charged single-layer photosensitive body" generally has the following structure: a base coat layer (UCL) composed of a resin or the like is provided on a conductive substrate such as an aluminum tube, and a single-layer photosensitive layer composed of a charge generating material (CGM), a hole transporting material (HTM), an electron transporting material (ETM) and a resin or the like is provided thereon (for example, refer to Patent Document 1).

[0006] In any photoreceptor, after the surface of the photoreceptor is charged by corona discharge or contact, the surface charge is neutralized by exposing the photoreceptor, thereby forming an electrostatic latent image due to the potential difference with the surrounding surface. Then, the toner is brought into contact with the surface of the photoreceptor to form a toner image corresponding to the electrostatic latent image, which is transferred / heated and melted to paper, etc., thereby completing printing.

[0007] As described above, the basic structure of the electrophotographic photoreceptor is a structure in which a photosensitive layer is formed on a conductive support. However, a protective layer may be provided on the photosensitive layer for the purpose of improving wear resistance and the like.

[0008] As a technology for improving the mechanical strength and even the wear resistance of the surface of a photoreceptor, a photoreceptor is disclosed, in which a layer containing a compound having a chain polymerizable functional group as a binder resin is formed on the outermost layer of the photoreceptor, and the layer is polymerized by applying energy such as heat, light, radiation, etc. to the layer to form a cured resin layer (for example, refer to patent documents 1 and 2). Prior art literature Patent Literature

[0009] Patent Document 1: U.S. Patent No. 9417538 Patent Document 2: International Publication No. 2010 / 035683 (Patent No. 5263296) Summary of the invention Problems to be solved by the invention

[0010] As described above, a protective layer is provided to improve the wear resistance of a photoreceptor. Among them, a protective layer using a curable compound is particularly excellent in mechanical strength. From the viewpoint of improving the electrical characteristics of the photoreceptor, such a protective layer is required to have electron transport properties. As a means for this purpose, it is considered effective to contain a compound having an electron transport structure in the protective layer using a curable compound. However, it is known that when a compound having an electron-transporting structure is contained in a protective layer, the electrical characteristics, in particular, the residual potential characteristics, become insufficient.

[0011] Therefore, the present invention relates to an electrophotographic photoreceptor including a photosensitive layer and a protective layer in this order on a conductive support, and provides a novel electrophotographic photoreceptor capable of improving electrical characteristics, particularly residual potential characteristics. Technical solutions to the problem

[0012] The inventors' research results show that the above-mentioned problems can be solved as long as the electrophotographic photoreceptor has at least a photosensitive layer and a protective layer in sequence on a conductive support, wherein the protective layer contains an electron-donating compound. In addition, it is known that even if the protective layer contains an electron-donating compound, the potential retention rate, hardness and elastic deformation rate remain unchanged and are good.

[0013] Therefore, the present invention proposes an electrophotographic photoreceptor, an electrophotographic photoreceptor cartridge, and an image forming apparatus according to the following embodiments.

[0014] A first embodiment of the present invention provides an electrophotographic photoreceptor, which is an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron-donating compound and a cured product formed by curing a photocurable compound. The electron donating compound is a compound having a benzimidazole structure or a guanidine structure.

[0015] A second embodiment of the present invention provides an electrophotographic photoreceptor, which is an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron-donating compound, The electron donating compound is a compound having a benzimidazole structure or a guanidine structure, The content of the electron donating compound in the protective layer is 0.62 parts by mass or more relative to 100 parts by mass of the total mass of the protective layer.

[0016] A third embodiment of the present invention provides an electrophotographic photoreceptor, which is an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron donating compound and an electron transporting compound, The content mass ratio of the electron donating compound to the electron transporting compound is 0.001 or more and 0.8 or less.

[0017] That is, the gist of the present invention lies in the following [1] to

[15] .

[0018] [1] An electrophotographic photoreceptor comprising at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron-donating compound and a cured product formed by curing a photocurable compound. The electron donating compound is a compound having a benzimidazole structure or a guanidine structure.

[0019] [2] An electrophotographic photoreceptor comprising at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron-donating compound, The electron donating compound is a compound having a benzimidazole structure or a guanidine structure, The content of the electron donating compound in the protective layer is 0.62 parts by mass or more relative to 100 parts by mass of the total mass of the protective layer.

[0020] [3] An electrophotographic photoreceptor comprising at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron donating compound and an electron transporting compound, The content mass ratio of the electron donating compound to the electron transporting compound is 0.001 or more and 0.8 or less.

[0021] [4] The electrophotographic photoreceptor according to [3], wherein the electron donating compound is a compound having two or more nitrogen atoms in a molecule. [5] The electrophotographic photoreceptor according to [3] or [4], wherein the electron donating compound is a compound having a benzimidazole structure or a guanidine structure.

[0022] [6] The electrophotographic photoreceptor according to any one of [1] to [5], wherein the electron donating compound is a compound represented by the following formula (2) or (3).

[0023]

[0024]

[0025] In the above formula (2), E 1 ~E 4 Each is independently a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkylthio group which may have a substituent, an arylthio group which may have a substituent, an arylsulfonyl group which may have a substituent, an amino group which may have a substituent, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, a hydroxyl group which may have a substituent, an alkoxy group which may have a substituent, an amide group which may have a substituent, an acyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, a carboxyl group which may have a substituent, a carboxamide group which may have a substituent, a carbonylalkoxy group which may have a substituent, an acyl group which may have a substituent, a sulfonyl group which may have a substituent, a cyano group which may have a substituent, or a nitro group which may have a substituent, or a derivative of any of them. In addition, E 1 ~E 4 They are optionally bonded to each other to form a ring. h is an integer greater than or equal to 0.

[0026] In formula (3), Ar T1 According to the above formula (4), G 1 is a hydrocarbon group which may have a substituent, and g1 is an integer of 1 or more.

[0027]

[0028] In formula (4), * represents the same as G in formula (3). 1 Bonding, G 2 It is an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a halogen atom, and g2 is an integer greater than or equal to 0.

[0029] [7] The electrophotographic photoreceptor according to [6], wherein the electron donating compound is at least one selected from the group consisting of compounds represented by the following formula.

[0030]

[0031] [8] The electrophotographic photoreceptor according to any one of [1], [2], [6] and [7], wherein the protective layer further contains an electron transporting compound. [9] The electrophotographic photoreceptor according to [8], wherein the content mass ratio of the electron donating compound to the electron transporting compound is 0.001 or more and 1.0 or less.

[0032]

[10] The electrophotographic photoreceptor according to any one of [3] to [5], [8] and [9], wherein the electron transporting compound is an electron transporting compound represented by the following formula (1).

[0033]

[0034] In formula (1), X represents an electron transport skeleton. R1 and R2 each independently represent a hydrogen atom or an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heteroaryloxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a dialkylamino group which may have a substituent, a diarylamino group which may have a substituent, an arylalkylamino group which may have a substituent, an acyl group which may have a substituent, a haloalkyl group which may have a substituent, an alkylthio group which may have a substituent, an arylthio group which may have a substituent, a silyl group which may have a substituent, a silyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. L1 represents a divalent group. Z1 represents a hydrogen atom, an alkoxy group, an amide group (-NHCO-R'), an acrylamide group, a methacrylamide group, an acryloyl group, or a methacryl group. The R' represents a hydrogen atom or an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic group which may have a substituent. a represents an integer of 1 or more. When a is an integer of 2 or more, R1, R2, L1 and Z1 in the repeating structure may be the same as or different from each other.

[0035]

[11] The electrophotographic photoreceptor according to

[10] , wherein the structure in which X in the formula (1) is substituted with a hydrogen atom at its bonding site is a structure selected from the group consisting of formulae (A-1) to (A-13) shown below.

[0036] It should be noted that in the formulas (A-1) to (A-13) shown below, P1 to P 21 Each independently represents a hydrogen atom, or an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aromatic group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an acyl group which may have a substituent, an ester group which may have a substituent, a cyano group which may have a substituent, a nitro group which may have a substituent, a sulfone group which may have a substituent, a hydroxyl group which may have a substituent, an aldehyde group which may have a substituent, or a halogen atom. m1 to m10 each independently represent an integer greater than 0. When m1 to m10 are each an integer greater than 2, P6 to P7 in the repeating structure are 15 Each of them can be the same or different from each other. 24Each independently represents an oxygen atom, a sulfur atom, C(CN)2, CR"CN, CA2, C(COOR")2, CR"COOR", NR" or NCR", wherein A represents a halogen atom, and R" represents a hydrogen atom or an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heteroaryloxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a dialkylamino group which may have a substituent, a diarylamino group which may have a substituent, an arylalkylamino group which may have a substituent, an acyl group which may have a substituent, a haloalkyl group which may have a substituent, an alkylthio group which may have a substituent, an arylthio group which may have a substituent, a silyl group which may have a substituent, a silyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar1 to Ar 19 Each independently represents an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent.

[0037]

[12] The electrophotographic photoreceptor according to

[10] or

[11] , wherein the structure formed by replacing the bonding site of X in the formula (1) with a hydrogen atom is a structure selected from the group consisting of the following formulae (B-1) to (B-38).

[0038] It should be noted that in the formulas (B-1) to (B-38) shown below, P1 to P 21 Each independently represents a hydrogen atom, or an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aromatic group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an acyl group which may have a substituent, an ester group which may have a substituent, a cyano group which may have a substituent, a nitro group which may have a substituent, a sulfone group which may have a substituent, a hydroxyl group which may have a substituent, an aldehyde group which may have a substituent, or a halogen atom. m1 to m10 each independently represent an integer greater than 0. When m1 to m10 are each an integer greater than 2, P6 to P7 in the repeating structure are 15 They are optionally the same as or different from each other.

[0039]

[13] An electrophotographic photoreceptor according to any one of

[10] to

[12] , wherein in the formula (1), L1 is an alkylene group, a divalent group having a keto group, a divalent group having an ether bond, a divalent group having an ester bond, or a group formed by connecting these groups.

[0040]

[14] An electrophotographic photosensitive body box comprising the electrophotographic photosensitive body described in any one of [1] to

[13] .

[15] An image forming device comprising the electrophotographic photoreceptor described in any one of [1] to

[13] . Effects of the Invention

[0041] In the electrophotographic photoreceptor proposed by the present invention, the protective layer contains an electron-donating compound, i.e., an electron dopant, which can improve the electron conductivity (electron transportability) in the protective layer, thereby making the electrical properties, especially the residual potential properties, of the electrophotographic photoreceptor good. In addition, even if the protective layer contains an electron-donating compound, the potential retention rate, hardness, and elastic deformation rate remain unchanged and become good. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a diagram schematically showing an example of the configuration of an image forming apparatus that can be configured using an electrophotographic photoreceptor according to an example of the present invention. Figure 2 This is a graph showing a general relationship between the indentation depth of the indenter and the load curve when measuring the Martens hardness and elastic deformation rate of the photoreceptor. Description of Reference Numerals 1 Photoreceptor (electrophotographic photoreceptor) 2 Charging device (charging roller; charging part) 3Exposure device (exposure unit) 4Developing device (developing unit) 5. Transfer device 6. Cleaning device 7Fixing device 41Developer Tank 42. Mixer 43 Supply roller 44Developing roller 45 Restricted parts 71 Upper fixing unit (pressure roller) 72 Lower fixing unit (fixing roller) 73 Heating device T-toner P recording paper (paper, medium) DETAILED DESCRIPTION

[0043] Hereinafter, the mode for implementing the present invention (hereinafter referred to as the embodiment of the invention) will be described in detail. It should be noted that the present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist thereof.

[0044] <<The present electrophotographic photoreceptor>> An electrophotographic photoreceptor according to an embodiment of the present invention (also referred to as “the present electrophotographic photoreceptor”) is an electrophotographic photoreceptor including at least a photosensitive layer and a protective layer in this order on a conductive support.

[0045] The present electrophotographic photoreceptor may optionally have layers other than the photosensitive layer and the protective layer. In addition, the charging method of the electrophotographic photoreceptor can be any one of a negative charging method for making the surface of the photoreceptor negatively charged and a positive charging method for making the surface of the photoreceptor positively charged. Among them, from the viewpoint of requiring electron transportability of the protective layer, it is believed that the positive charging method can further enjoy the effect of the present invention, and therefore the positive charging method is preferred.

[0046] In the present electrophotographic photoreceptor, the side opposite to the conductive support is the upper side or the surface side, and the conductive support side is the lower side or the back side.

[0047] <This protective layer> The protective layer preferably contains an electron-donating compound, particularly preferably contains an electron-transporting compound, and further preferably contains a cured product formed by curing a curable compound. That is, the present protective layer preferably contains, in addition to the electron donating compound, any one or both of an electron transporting compound and a cured product obtained by curing the curable compound.

[0048] Here, in the present invention, "electron donating compound" refers to a compound that can donate electrons to the protective layer. In other words, "electron donating compound" refers to a compound that can reduce the energy barrier (energy barrier) during electron transfer in the target compound (electron transport compound) in the protective layer by any mechanism and inject electrons into the target compound. As the mechanism, for example, electrons can be directly transferred from the electron donating compound to the target compound, or electrons can be transferred by forming a hydrogen bond between the electron donating compound and the target compound, or the energy barrier (energy barrier) during electron transfer can be reduced by forming a hydrogen bond between the electron donating compound and the target compound, and the electrons transferred from the photosensitive layer can be injected into the target compound present in the protective layer. Examples of conventionally known electron donating compounds include compounds having structures such as triphenylmethane, acridine, amine, amidine, aniline, pyridine, xanthene, benzimidazole, guanidine, and phosphazene. Compounds for which such an action has been confirmed are also included. In the present invention, the "electron transporting compound" refers to a compound having an electron transporting property, in other words, a compound having an electron transporting skeleton.

[0049] The protective layer may be formed of a composition containing an electron donating compound and, if necessary, an electron transporting compound, a curable compound, a polymerization initiator, inorganic particles, and other materials, for example. However, the protective layer is not limited to being formed of such a composition.

[0050] From the perspective of further obtaining the effects of the present invention, the protective layer is preferably the outermost layer, that is, the outermost layer located on the opposite side of the conductive support. However, the protective layer does not have to be the outermost layer to obtain the effects of the present invention. For example, in the case where there is a segregation layer on the outermost layer of the photoreceptor, the effects can be obtained even if the protective layer is not the outermost layer.

[0051] (Electron Donating Compounds) As described above, as electron donating compounds, for example, compounds having structures such as triphenylmethane, acridine, amine, amidine, aniline, pyridine, xanthene, benzimidazole, guanidine, and phosphazene can be cited. Among them, from the viewpoint of stability, compounds having a benzimidazole structure or a guanidine structure are preferred. In addition, as the guanidine structure, any of a chain guanidine structure and a cyclic guanidine structure can be used. From the viewpoint of stability, a cyclic guanidine structure is preferred. As the electron donating compound, it is preferably a compound having one or more heteroatoms in the molecule, wherein it is more preferably a compound having one or more nitrogen atoms (N atoms) in the molecule. From the viewpoint of stability, the number of heteroatoms in one molecule of the electron donating compound is preferably one or more, more preferably two or more, and further preferably three or more. In addition, from the viewpoint of electron donating energy, the number of nitrogen atoms (N atoms) in one molecule of the electron donating compound is preferably one or more, more preferably two or more, and further preferably three or more. In addition, as the electron donating compound, a compound having one or more cyclic structures is preferred from the viewpoint of stability.

[0052] The electron donating compound is preferably an electron donating compound represented by the following formula (2) or (3). These electron-donating compounds are activated, for example, when heated to above room temperature, and can supply electrons to the present protective layer. Specifically, the electron-donating compound represented by the following formula (2) is activated when heated to above about 80°C, and can supply electrons to the present protective layer. The electron-donating compound represented by the following formula (3) is activated when heated to above room temperature, and can supply electrons to the present protective layer. Therefore, for example, when forming the present protective layer, due to the temperature rise accompanying ultraviolet irradiation, these compounds are activated and can supply electrons to the present protective layer.

[0053]

[0054]

[0055] In formula (2), E 1 ~E 4Each of them is independently preferably a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, a thioalkyl group which may have a substituent, a thioaryl group which may have a substituent, an arylsulfonyl group which may have a substituent, an amino group which may have a substituent, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, a hydroxy group which may have a substituent, an alkoxy group which may have a substituent, an amide group which may have a substituent, an acyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, a carboxyl group which may have a substituent, a carboxyamide group which may have a substituent, a carboxyalkoxy group which may have a substituent, an acyl group which may have a substituent, a sulfonyl group which may have a substituent, a cyano group which may have a substituent, a nitro group which may have a substituent, or a derivative of any of these groups. In addition, E 1 ~E 4 They are optionally bonded to each other to form a ring.

[0056] In addition, in the present invention, "may have a substituent" means that it may have a substituent, and includes both the case of having a substituent and the case of not having a substituent.

[0057] In the above formula (2), h is an integer of 0 or more, preferably 2 or less, more preferably 1 or less, and even more preferably 0, from the viewpoint of stability.

[0058] In the above formula (3), g1 is an integer of 1 or more, preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less, from the viewpoint of electrical properties.

[0059] In the above formula (3), Ar T1 Preferred is a compound represented by the following formula (4). G 1 Preferably, it is a hydrocarbon group which may have a substituent. The number of carbon atoms of the hydrocarbon group is preferably 1 or more, more preferably 3 or more, and on the other hand, it is preferably 12 or less, more preferably 10 or less. When g1 is 1, the hydrocarbon group is preferably an alkyl group, for example, methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, decyl, etc. When g1 is 2, the hydrocarbon group is preferably an alkylene group, for example, methylene, vinyl, etc.

[0060]

[0061] In formula (4), * represents the same as G in formula (3). 1 bonding. G 2 An alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a halogen atom is preferred.

[0062] In formula (4), g2 is an integer greater than or equal to 0, preferably less than or equal to 2, more preferably less than or equal to 1, and most preferably less than or equal to 0 from the viewpoint of stability.

[0063] From the viewpoint of electrical properties, the content of the electron-donating compound in the protective layer is preferably 0.10 parts by mass or more, more preferably 0.62 parts by mass or more, more preferably 0.70 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 2.0 parts by mass or more, relative to the total mass of 100 parts by mass of the protective layer. On the other hand, from the viewpoint of electrical properties, relative to the total mass of 100 parts by mass of the protective layer, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less, wherein it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, further preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. It should be noted that the total mass of the protective layer refers to the total mass of the protective layer after curing, which is consistent with the total mass of the solid content in the coating solution for forming the protective layer.

[0064] Specific examples of the electron donating compound are shown below, but the present invention is not limited to these.

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] (Electron transporting compound) The electron-transporting compound used in the present protective layer is preferably a compound represented by the following formula (1). When the electron transporting compound exists in this protective layer together with the above-mentioned electron donating compound, the electron transporting compound becomes more receptive to electrons by supplying electrons to the electron donating compound, and its performance, i.e., the electron transporting performance is activated, which can further improve the electron transporting property of this protective layer and enable the electrical properties, especially the residual potential properties, of this electronic photographic photosensitive body to become better.

[0080]

[0081] [Electron transport skeleton: X] In the above formula (1), X may be a structure having electron-transporting properties, that is, an electron-transporting skeleton, and a known electron-transporting skeleton may be appropriately adopted. As the electron transport skeleton, for example, an anthraquinone skeleton, a dinaphthoquinone skeleton, a phthalimide skeleton, a naphthalimide skeleton, a perylene diimide skeleton, an isoindigo skeleton, a diketopyrrolopyrrole skeleton, a thiadiazole skeleton, a pyrazine skeleton, etc. Among them, from the viewpoint of electron transport and solubility, a dinaphthoquinone skeleton, a phthalimide skeleton, a naphthalimide skeleton, a perylene diimide skeleton are preferred, a phthalimide skeleton, a naphthalimide skeleton, a perylene diimide skeleton are more preferred, and a phthalimide skeleton, a naphthalimide skeleton, a perylene diimide skeleton are further preferred.

[0082] The structure in which X in the above formula (1) is substituted with a hydrogen atom at its bonding site is preferably a structure selected from the group consisting of the following formulae (A-1) to (A-13).

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096] In the above formulas (A-1) to (A-13), P1 to P 21 Each of them is independently preferably a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an acyl group which may have a substituent, an ester group which may have a substituent, a cyano group which may have a substituent, a nitro group which may have a substituent, a sulfone group which may have a substituent, a hydroxyl group which may have a substituent, an aldehyde group which may have a substituent, or a halogen atom. Among them, from the viewpoint of solubility and curability, a hydrogen atom or an alkyl group which may have a substituent is more preferred, and a hydrogen atom is further preferred.

[0097] In the above formulae (A-1) to (A-13), m1 to m10 may each independently represent an integer greater than 0. In particular, from the viewpoint of solubility and curability, m1 to m10 are each preferably each independently represent an integer greater than 1. It should be noted that when m1 to m10 are each an integer greater than 2, P6 to P10 in the repeating structure 15 They are optionally the same as or different from each other.

[0098] In the above formulas (A-1) to (A-13), Q1 to Q 24 Each is independently preferably any one of an oxygen atom, a sulfur atom, C(CN)2, CR"CN, CA2, C(COOR")2, CR"COOR", NR" or NCR". Among them, from the viewpoint of electron transport properties, an oxygen atom, C(CN)2, CR"CN is preferred, and an oxygen atom, C(CN)2 is more preferred. It should be noted that A represents a halogen atom, and R" is preferably a hydrogen atom or an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heteroaryloxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a dialkylamino group which may have a substituent, a diarylamino group which may have a substituent, an arylalkylamino group which may have a substituent, an acyl group which may have a substituent, a haloalkyl group which may have a substituent, an alkylthio group which may have a substituent, an arylthio group which may have a substituent, a silyl group which may have a substituent, a silyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Among them, from the viewpoint of solubility, R" is preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, and more preferably an alkyl group.

[0099] In the above formulas (A-1) to (A-13), Ar1 to Ar 19 Each independently is preferably an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent. Among them, an aromatic group which may have a substituent is more preferred from the viewpoint of solubility. Among the above formulas (A-1) to (A-13), from the viewpoint of electron transport properties, preferred are (A-1), (A-2), (A-3), (A-6), and (A-9), more preferred are (A-2), (A-3), and (A-9), and further preferred are (A-2) and (A-3).

[0100] Among them, the structure in which X in the above formula (1) is substituted with a hydrogen atom at its bonding site is more preferably a structure selected from the group consisting of the following formulae (B-1) to (B-38).

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139] In the above formulas (B-1) to (B-38), P1 to P 21Each of them is independently preferably a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an acyl group which may have a substituent, an ester group which may have a substituent, a cyano group which may have a substituent, a nitro group which may have a substituent, a sulfone group which may have a substituent, a hydroxyl group which may have a substituent, an aldehyde group which may have a substituent, or a halogen atom. Among them, from the viewpoint of solubility and curability, a hydrogen atom or an alkyl group which may have a substituent is more preferred, and a hydrogen atom is further preferred.

[0140] In the above formulae (B-1) to (B-38), m1 to m10 may each independently represent an integer greater than 0. Among them, m1 to m10 may each independently represent an integer greater than 1, preferably from the viewpoint of solubility and curability. It should be noted that when m1 to m10 are each an integer greater than 2, P6 to P10 in the repeating structure 15 They are optionally the same as or different from each other. In the above formulas (B-1) to (B-38), from the viewpoint of solubility and electron transport properties, preferred are (B-1), (B-2), (B-7), (B-12), (B-14), (B-15), (B-16), (B-24), and (B-30), more preferred are (B-7), (B-12), (B-14), (B-15), (B-16), and (B-30), and further preferred are (B-7), (B-14), (B-15), and (B-16).

[0141] [Z1] In the above formula (1), Z1 represents a hydrogen atom, an alkoxy group, an amide group (-NHCO-R'), an acrylamide group, a methacrylamide group, an acryloyl group or a methacryloyl group. It should be noted that R' in the amide group (-NHCO-R') represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aromatic group which may have a substituent. Among them, an alkyl group which may have a substituent is preferred from the viewpoint of solubility.

[0142] In formula (1), Z1 is more preferably an alkoxy group, an amide group (-NHCO-R'), an acrylamide group, a methacrylamide group, an acryloyl group or a methacryloyl group, and from the viewpoint of improving the mechanical strength of the protective layer, it is further preferably an acrylamide group, a methacrylamide group, an acryloyl group or a methacryloyl group. In other words, in formula (1), at least one Z1 is further preferably an acrylamide group, a methacrylamide group, an acryloyl group or a methacryloyl group. In this case, it can also function as a chain polymerizable functional group and can be cross-linked with the curable compound in the protective layer, so the mechanical strength, such as hardness and elastic deformation rate of the protective layer is better.

[0143] [R1, R2] In formula (1), R1 and R2 are each independently preferably a hydrogen atom or an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heteroaryloxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a dialkylamino group which may have a substituent, a diarylamino group which may have a substituent, an arylalkylamino group which may have a substituent, an acyl group which may have a substituent, a haloalkyl group which may have a substituent, an alkylthio group which may have a substituent, an arylthio group which may have a substituent, a silyl group which may have a substituent, a silyloxy group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Among them, a hydrogen atom or an alkyl group which may have a substituent is more preferred from the viewpoint of solubility.

[0144] In the formula (1), if at least one of R1 and R2 is an alkyl group having 2 or more carbon atoms and optionally having a substituent, a more excellent effect can be obtained in terms of dark attenuation, which is particularly preferred.

[0145] [L1] In formula (1), L1 can be a divalent group. For example, it can be an alkylene group, a divalent group having a ketone group, a divalent group having an ether bond, a divalent group having an ester bond, or a group formed by connecting them. However, it is not limited to these. Among them, from the viewpoint of solubility, the structure represented by the following formulas (L-1) to (L-5) is preferred, among which formula (L-3), formula (L-4), and formula (L-5) are more preferred.

[0146]

[0147] In the above formulae (L-1) to (L-5), * represents a carbon atom or a bonding site of Z1 to which R1 and R2 in formula (1) are bonded.

[0148] In formula (1), L1 is the connecting portion of the carbon atom bonded to R1 and R2 and bonded to Z1, and the carbon atom bonded to R1 and R2 is further bonded to the electron transport skeleton, so L1 can also be said to be the connecting portion of the electron transport skeleton and Z1 bonded. It is believed that Z1 is less susceptible to the interaction of the electron transport skeleton when it is away from the electron transport skeleton, especially when Z1 contains an amide bond, which enhances the effect of the amide bond, that is, the effect of affinity with the solvent. From this point of view, it is believed that the number of atoms in the main chain of L1 is preferably 4 or more.

[0149] [a] In the above formula (1), the portion other than the electron transport skeleton X may be a repeating structure, and a in the above formula (1) represents the number of the repeating structure. That is, in the above formula (1), a may be an integer of 1 or more, and preferably 2 or more from the viewpoint of solubility and curability. It should be noted that when a is an integer greater than or equal to 2, R1, R2, L1 and Z1 in the repeating structure in the above formula (1) may be the same or different.

[0150] Specific examples of the electron transporting compound are shown below, but the present invention is not limited to these.

[0151]

[0152] From the perspective of electron transport, the content of the electron transport compound in the protective layer is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, and further preferably 80 parts by mass or more, relative to 100 parts by mass of the total mass of the protective layer. It should be noted that the total mass of the protective layer refers to the total mass of the protective layer after curing, which is consistent with the total mass of the solid content in the coating solution for forming the protective layer.

[0153] (Content ratio of electron donating compound and electron transporting compound) From the viewpoint of electrical properties, the mass ratio of the electron-donating compound to the electron-transporting compound (electron-donating compound / electron-transporting compound) is preferably 0.001 or more, more preferably 0.005 or more, more preferably 0.01 or more, more preferably 0.02 or more. On the other hand, from the viewpoint of electrical properties, it is preferably 1.0 or less, more preferably 0.8 or less, more preferably 0.7 or less, more preferably 0.6 or less, particularly preferably 0.4 or less, particularly preferably 0.1 or less, and particularly preferably 0.04 or less.

[0154] (Curing compound) The curable compound can be any compound having a chain polymerizable functional group. Among them, monomers, oligomers or polymers having free radical polymerizable functional groups are preferred. Among them, cross-linking curable compounds are preferred, and photocurable compounds are particularly preferred. For example, curable compounds having two or more free radical polymerizable functional groups can be mentioned. Compounds having one free radical polymerizable functional group can also be used in combination. Examples of the radical polymerizable functional group include either or both of an acryloyl group (including an acryloyloxy group) and a methacryloyl group (including a methacryloyloxy group).

[0155] Hereinafter, preferred compounds are exemplified as the photocurable compound having a radical polymerizable functional group. Examples of the monomer having an acryloyl group or a methacryloyl group include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerol triacrylate, tri(acryloyloxyethyl)isocyanurate, dipentaerythritol hexaacrylate, dimethylolpropane tetraacrylate, pentaerythritol ethoxy tetraacrylate, EO-modified phosphoric acid triacrylate, 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, polyethylene glycol dipropylene glycol, and the like. Acid ester, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, EO modified bisphenol A diacrylate, PO modified bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, tricyclodecane dimethanol diacrylate, decanediol diacrylate, hexanediol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, EO modified bisphenol A dimethacrylate, PO modified bisphenol A dimethacrylate, tricyclodecane dimethanol dimethacrylate, decanediol dimethacrylate, hexanediol dimethacrylate, etc.

[0156] Examples of oligomers and polymers having an acryloyl group or a methacryloyl group include urethane acrylates, ester acrylates, acrylic acrylates, epoxy acrylates, etc. Among them, urethane acrylates and ester acrylates are preferred, and ester acrylates are more preferred.

[0157] The above-mentioned curable compounds may be used alone or in combination of two or more.

[0158] From the viewpoint of electron transport properties, the content mass ratio of the curable compound to the electron donating compound in the protective layer (curable compound / electron donating compound) is preferably 40 or less, more preferably 30 or less, and even more preferably 20 or less. From the viewpoint of electron transporting property, the content mass ratio of the curable compound to the electron transporting compound in the protective layer (curable compound / electron transporting compound) is preferably 1.0 or less, more preferably 0.5 or less, and further preferably 0.1 or less.

[0159] (Polymerization initiator) Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator. Examples of the thermal polymerization initiator include peroxide compounds such as 2,5-dimethylhexane-2,5-dihydroperoxide and azo compounds such as 2,2′-azobis(isobutyronitrile).

[0160] Photopolymerization initiators can be divided into direct cleavage type and hydrogen abstraction type according to the different free radical generation mechanisms. When a direct cleavage type photopolymerization initiator absorbs light energy, some of the covalent bonds in the molecule break to generate free radicals. On the other hand, in a hydrogen abstraction type photopolymerization initiator, the molecule that becomes excited by absorbing light energy generates free radicals by abstracting hydrogen from a hydrogen donor.

[0161] Examples of direct cleavage-type photopolymerization initiators include acetophenone-based or ketal-based compounds such as acetophenone, 2-benzoyl-2-propanol, 1-benzoylcyclohexanol, 2,2-diethoxyacetophenone, benzyl dimethyl ketal, and 2-methyl-4′-(methylthio)-2-morpholinopropiophenone; benzoin ether-based compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, and O-toluenesulfonylbenzoin; and acylphosphine oxide-based compounds such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and phenyl(2,4,6-trimethylbenzoyl)phosphine lithium phosphonate.

[0162] Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, 4-benzoylbenzoic acid, 2-benzoylbenzoic acid, methyl 2-benzoylbenzoate, methyl benzoylformate, benzil, p-anisil, 2-benzoylnaphthalene, 4,4'-bis(dimethylamino)benzophenone, 4,4'-dichlorobenzophenone, 1,4-dibenzoylbenzene and other benzophenone-based compounds, and anthraquinone-based or thioxanthone-based compounds such as 2-ethylanthraquinone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone. As another photopolymerization initiator, camphorquinone, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, an acridine compound, a triazine compound, and an imidazole compound are mentioned, for example.

[0163] In order to efficiently absorb light energy and generate radicals, the photopolymerization initiator preferably has an absorption wavelength within the wavelength range of the light source used for light irradiation. Among them, it is preferred to contain an acylphosphine oxide-based compound having an absorption wavelength on the relatively long wavelength side. In addition, from the viewpoint of supplementing the curability of the protective layer surface, it is further preferred to use an acylphosphine oxide compound and a hydrogen abstraction type initiator in combination. In this case, the content ratio of the hydrogen abstraction type initiator relative to the acylphosphine oxide compound is not particularly limited. From the viewpoint of supplementing the surface curability, it is preferably 0.1 parts by mass or more relative to 1 part by mass of the acylphosphine oxide compound, and from the viewpoint of maintaining the internal curability, it is preferably 5 parts by mass or less.

[0164] In addition, an initiator having a photopolymerization accelerating effect may be used alone or in combination with the above-mentioned photopolymerization initiator. Examples of initiators having a photopolymerization accelerating effect include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isopentyl 4-dimethylaminobenzoate, (2-dimethylamino)ethyl benzoate, and 4,4'-dimethylaminobenzophenone.

[0165] The polymerization initiator may be used alone or in combination of two or more. The content of the polymerization initiator is preferably 0.5 to 40 parts by mass, more preferably 1 part by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total radical polymerizable content. The radical polymerizable total content includes the electron transporting compound represented by the above formula (1) and the curable compound.

[0166] (Inorganic particles) From the viewpoint of improving strong exposure characteristics and mechanical strength and also from the viewpoint of imparting charge transporting ability, the present protective layer may contain inorganic particles. However, it is not necessary to contain inorganic particles.

[0001] Examples of the inorganic particles include metal powders, metal oxides, metal fluorides, potassium titanate, and boron nitride. Any inorganic particles that can be used in electrophotographic photoreceptors can be used. As the inorganic particles, only one kind of particles may be used, or a plurality of kinds of particles may be mixed and used.

[0168] (Other materials) This protective layer may also contain other materials as required. As other materials, for example, stabilizers (heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, etc.), dispersants, antistatic agents, colorants, lubricants, etc. can be mentioned. They can be used alone or in any ratio and combination of two or more.

[0169] (Method for forming the protective layer) [Coating liquid for forming protective layer] The present protective layer can be formed, for example, by applying a coating liquid formed by dissolving a curable composition containing an electron-donating compound and, if necessary, an electron-transporting compound, a curable compound, a polymerization initiator, inorganic particles, and other materials in a solvent or a coating liquid dispersed in a dispersion solvent (referred to as "the present protective layer-forming coating liquid") on the present photosensitive layer and curing the coating liquid. However, the present protective layer is not limited to this method. It should be noted that, when the electron transport compound has a chain polymerizable functional group such as an acrylamide group, a methacrylamide group, an acryloyl group or a methacryl group, it can have the function of a curable compound. In this case, it is possible to not contain a curable compound other than the electron transport compound having a chain polymerizable functional group. Even in the case of not containing a curable compound or in the case of a small amount of curable compound, by using the electron transport compound having a chain polymerizable functional group, the mechanical strength of the protective layer can be fully obtained, and the residual potential caused by containing a curable compound can be suppressed. Deterioration. However, it does not exclude the use of an electron transport compound and a curable compound having a chain polymerizable functional group.

[0170] The electron donating compound used in the present protective layer-forming coating liquid is preferably a compound represented by the above formula (2) or (3). The electron transporting compound used in the present protective layer-forming coating liquid is preferably a compound represented by the above formula (1). Preferred aspects of the curable compound, polymerization initiator, inorganic particles, and other materials used in the coating solution for forming the protective layer are the same as those of the materials used in the protective layer.

[0171] The content ratio of the electron donating compound to the electron transporting compound in the protective layer-forming coating liquid (electron donating compound / electron transporting compound) is the same as the content mass ratio of the electron donating compound to the electron transporting compound in the protective layer described above (electron donating compound / electron transporting compound). The content ratio of the curable compound to the electron donating compound in the protective layer-forming coating liquid is the same as the content mass ratio of the curable compound to the electron donating compound in the protective layer described above. The content ratio of the curable compound to the electron transporting compound in the coating liquid for forming the protective layer (curable compound / electron transporting compound) is the same as the content mass ratio of the curable compound to the electron transporting compound in the protective layer described above (curable compound / electron transporting compound).

[0172] From the viewpoint of electrical properties, the content of the electron-donating compound in the coating solution for forming a protective layer is preferably 0.06 parts by mass or more, more preferably 0.10 parts by mass or more, and further preferably 0.14 parts by mass or more, relative to 100 parts by mass of the solvent. On the other hand, from the viewpoint of solubility, it is preferably 1.30 parts by mass or less, more preferably 1.00 parts by mass or less, and further preferably 0.70 parts by mass or less, relative to 100 parts by mass of the solvent. From the viewpoint of film uniformity of the protective layer, the content of the electron transporting compound in the coating solution for forming the protective layer is preferably 4 parts by mass or more, more preferably 6 parts by mass or more, and further preferably 8 parts by mass or more, relative to 100 parts by mass of the solvent. On the other hand, from the viewpoint of solubility, it is preferably 14 parts by mass or less, more preferably 12 parts by mass or less, and further preferably 10 parts by mass or less, relative to 100 parts by mass of the solvent. From the viewpoint of film uniformity of the protective layer, the content of the curable compound in the coating solution for forming the protective layer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 4 parts by mass or more, relative to 100 parts by mass of the solvent. On the other hand, from the viewpoint of solubility, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 6 parts by mass or less, relative to 100 parts by mass of the solvent. In particular, when the electron transport compound contained in the coating liquid for forming the protective layer has a chain polymerizable functional group, from the viewpoint of residual potential, the content of the curable compound in the coating liquid for forming the protective layer is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 0 parts by mass, relative to 100 parts by mass of the solvent.

[0173] As the solvent used in the coating liquid for forming the protective layer, an organic solvent can be used, for example. Examples of the organic solvent include: alcohols such as methanol, ethanol, propanol, and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane, and dimethoxyethane; esters such as methyl formate and ethyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and anisole; chlorinated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, and trichloroethylene; nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, and triethylenediamine; aprotic polar solvents such as acetonitrile, N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide, etc. A mixed solvent in any combination and any proportion can also be used from these. Among them, alcohols, ethers, aromatic hydrocarbons, and aprotic polar solvents are preferred from the viewpoint of solubility and coating properties, alcohols, ethers, and aromatic hydrocarbons are more preferred, alcohols and ethers are further preferred, and alcohols are most preferred. In addition, even an organic solvent that does not dissolve the electron-donating compound used in the protective layer of the present electrophotographic photoreceptor when used alone can be used as long as it can be dissolved by, for example, making a mixed solvent with the above-mentioned organic solvent. Generally, the use of a mixed solvent can reduce uneven coating. In the case of using an immersion coating method in the coating method described later, it is preferred to select a solvent that does not dissolve the lower layer. From this point of view, it is particularly preferred to contain alcohols.

[0174] The quantitative ratio of the solvent to the solid content used in the protective layer-forming coating liquid varies depending on the coating method of the protective layer-forming coating liquid, and can be appropriately changed so as to form a uniform coating film in an appropriate coating method.

[0175] [Coating method] The coating method of the coating liquid for forming the present protective layer is not particularly limited, and examples thereof include spray coating, spin coating, ring coating, and dip coating.

[0176] After forming the coating film by the above coating method, the coating film is dried. At this time, the drying temperature and time are not limited as long as necessary and sufficient drying can be obtained. However, in the case where the protective layer is applied only by air drying after the photosensitive layer is applied, it is preferred to perform sufficient drying by the method described in the method for forming the photosensitive layer described later.

[0177] [Curing method of the protective layer] The present protective layer can be formed by applying the present protective layer-forming coating liquid and then applying energy from the outside to cure the coating liquid. Examples of the external energy used in this case include heat, light, and radiation.

[0178] As a method of applying heat energy, there can be mentioned: heating methods using air, gas such as nitrogen, steam or various heat media, infrared rays, and electromagnetic waves. In addition, the heating can be performed from the coating surface side or the support side. The heating temperature is preferably 100° C. or more and 170° C. or less.

[0179] As light energy, UV irradiation light sources such as high pressure mercury lamps, metal halide lamps, electrodeless bulbs, and light emitting diodes having an emission wavelength in the ultraviolet (UV) range can be used. In addition, a visible light source can be selected to match the absorption wavelength of the chain polymerizable compound or photopolymerization initiator. From the viewpoint of curability, the light irradiation amount is preferably 10 J / cm 2 More preferably, 30 J / cm 2 More than 100 J / cm 2 In addition, from the viewpoint of electrical properties, 500 J / cm 2 Below, more preferably 300 J / cm 2 Below, particularly preferably 200 J / cm 2 the following. On the other hand, as the energy of radiation, there is mentioned the energy using electron beam (EB).

[0180] Among these energies, light energy is preferably used from the viewpoints of ease of reaction rate control, simplicity of the device, and length of pot life.

[0181] After curing the protective layer, a heating step may be added from the viewpoint of relaxing residual stress, relaxing residual free radicals, and improving electrical properties. The heating temperature is preferably 60° C. or higher, more preferably 100° C. or higher, preferably 200° C. or lower, and more preferably 150° C. or lower.

[0182] (Layer Thickness) From the viewpoint of wear resistance, the thickness of the protective layer is preferably 0.5 μm or more, more preferably 1 μm or more, while from the viewpoint of electrical properties, it is preferably 5 μm or less, more preferably 3 μm or less. In addition, from the same viewpoint, the thickness of the protective layer is preferably 1 / 50 or more, more preferably 1 / 40 or more, and more preferably 1 / 30 or more relative to the thickness of the photosensitive layer. On the other hand, it is preferably less than 1 / 5, more preferably less than 1 / 10, and more preferably less than 1 / 20.

[0183] <This photosensitive layer> The photosensitive layer in the present electrophotographic photoreceptor (also referred to as "present photosensitive layer") may be a layer containing at least a charge generating material (CGM) and a charge transporting material.

[0184] The photosensitive layer may be a single-layer photosensitive layer containing both a charge generating material and a charge transporting material in the same layer, or may be a laminated photosensitive layer separated into a charge generating layer and a charge transporting layer.

[0185] <Single-layer photosensitive layer> When the present photosensitive layer is a single-layer photosensitive layer, it is preferred that at least a charge generating material (CGM), a hole transporting material (HTM), an electron transporting material (ETM), and a binder resin are contained in the same layer.

[0186] (Charge Generating Material) As the charge generating material used in the photosensitive layer, various photoconductive materials such as inorganic photoconductive materials and organic pigments can be used. Among them, organic pigments are particularly preferred, and phthalocyanine pigments and azo pigments are more preferred.

[0187] In particular, when phthalocyanine pigments are used as charge generating materials, specifically, metal-free phthalocyanines, phthalocyanines coordinated by metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or their oxides, halides, etc. are used. Among them, X-type and τ-type metal-free phthalocyanines, A-type, B-type, D-type oxytitanium phthalocyanines, oxyvanadium phthalocyanines, chloroindium phthalocyanines, chlorogallium phthalocyanines, hydroxygallium phthalocyanines, etc., which have high sensitivity, are particularly preferred.

[0188] When an azo pigment is used, it is preferable to use various known disazo pigments and trisazo pigments.

[0189] In addition, the charge generating material may be used alone or in any combination and ratio. Furthermore, when two or more charge generating materials are used in combination, the charge generating materials used in combination may be mixed and used later, or may be mixed and used in the production / processing steps of the charge generating materials such as synthesis, pigmentation, and crystallization.

[0190] From the viewpoint of electrical properties, it is desirable that the particle size of the charge generating material is small. Specifically, the particle size of the charge generating material is preferably 1 μm or less, more preferably 0.5 μm or less. The lower limit is 0.01 μm or more. The particle size of the charge generating material here refers to the particle size in the state of being contained in the photosensitive layer.

[0191] Furthermore, from the viewpoint of sensitivity, the amount of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and from the viewpoint of sensitivity and charging properties, preferably 50% by mass or less, more preferably 20% by mass or less.

[0192] (Charge Transport Material) Charge transport materials are divided into hole transport materials that mainly have hole transport capability and electron transport materials that mainly have electron transport capability. However, when the photosensitive layer is a single-layer photosensitive layer, it is preferred that at least a hole transport material and an electron transport material are contained in the same layer.

[0193] [Hole transport material] Hole transport materials (HTM) can be selected from known materials. Examples include heterocyclic compounds such as carbazole derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, and benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, and enamine derivatives, as well as products of combinations of multiple of these compounds, and electron-donating materials such as polymers having groups composed of these compounds in the main chain or side chain.

[0194] Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and products of combining two or more of these compounds are preferred, and aromatic amine derivatives and enamine derivatives are more preferred.

[0195] The hole transporting material may be used alone or in combination of two or more. From the viewpoint of hole transportability, the amount of hole transport material in the monolayer photosensitive layer is preferably 20% by mass or more, more preferably 30% by mass or more, relative to 100% by mass of the entire photosensitive layer. In addition, from the viewpoint of solubility, it is preferably 55% by mass or less, more preferably 45% by mass or less.

[0196] [Electron transport substances] The electron transport material (ETM) can be selected from known materials. For example, it can be: an aromatic nitro compound such as 2,4,7-trinitrofluorenone, a cyano compound such as tetracyanoquinodimethane, an electron-withdrawing substance such as a quinone compound such as dibenzoquinone, a known cyclic ketone compound, a perylene pigment (perylene derivative), etc. Among these, from the viewpoint of electrical properties, a quinone compound and a perylene pigment (perylene derivative) are preferred, and a quinone compound is more preferred. Among the quinone compounds, dibenzoquinone or dinaphthoquinone is preferred from the viewpoint of electrical properties, and dinaphthoquinone is more preferred.

[0197] The electron transport material may be used alone or in combination of two or more. From the viewpoint of electron transportability, the amount of electron transport material in the monolayer photosensitive layer is preferably 15% by mass or more, more preferably 25% by mass or more, relative to the entire 100% by mass of the photosensitive layer. In addition, from the viewpoint of solubility, it is preferably 40% by mass or less, more preferably 30% by mass or less.

[0198] The structures of preferred electron transport substances are exemplified below.

[0199]

[0200] Among the above-mentioned electron transport materials, ET-2 and ET-5 are preferred, and ET-2 is more preferred, from the viewpoint of electrical characteristics.

[0201] (Binder resin) Next, the binder resin used in the present photosensitive layer will be described. As the binder resin used in the photosensitive layer, for example, there can be mentioned: vinyl polymers such as polymethyl methacrylate, polystyrene, polyvinyl chloride or their copolymers; vinyl alcohol resin; polyvinyl butyral resin; polyvinyl formal resin; partially modified polyvinyl acetal resin; polyarylate resin; polyamide resin; polyurethane resin; polycarbonate resin; polyester resin; polyester carbonate resin; polyimide resin; phenoxy resin; epoxy resin; silicone resin; and their partially crosslinked cured products. In addition, the above resins can also be modified with silicon reagents, etc. In addition, these can be used alone or in any ratio and combination of two or more.

[0202] In addition, the binder resin used in the present photosensitive layer preferably contains one or two or more polymers obtained by interfacial polymerization.

[0203] As the binder resin obtained by the above-mentioned interfacial polymerization, polycarbonate resins and polyester resins are preferred, and polycarbonate resins and polyarylate resins are particularly preferred. In addition, polymers made from aromatic diols are particularly preferred.

[0204] (Other substances) In addition to the above materials, in order to improve film-forming properties, flexibility, coating properties, pollution resistance, gas resistance, light resistance, etc., the present photosensitive layer may also contain additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents. In addition, the present photosensitive layer may also contain various additives such as sensitizers, dyes, pigments (excluding the above-mentioned charge generating substances, hole transport substances, and electron transport substances), surfactants, etc. as needed. Examples of surfactants include silicone oils, fluorine compounds, etc. In the present invention, these additives may be used alone or in any ratio and combination of two or more.

[0205] In order to reduce the friction resistance of the surface of the photosensitive layer, the photosensitive layer may contain fluorine-based resins, silicone resins, etc., and may also contain particles composed of these resins, and particles of inorganic compounds such as alumina.

[0206] (Layer Thickness) When the photosensitive layer is a single-layer photosensitive layer, the thickness of the photosensitive layer is preferably 20 μm or more, more preferably 25 μm or more, from the viewpoint of dielectric breakdown resistance. On the other hand, from the viewpoint of electrical properties, it is preferably 50 μm or less, more preferably 40 μm or less.

[0207] <Laminated photosensitive layer> When the electrophotographic photoreceptor is a laminated photosensitive layer, for example, a structure in which a charge transport layer (CTL) containing a charge transport material is laminated on a charge generating layer (CGL) containing a charge generating material (CGM) may be mentioned. In this case, other layers other than the charge generating layer (CGL) and the charge transport layer (CTL) may also be included.

[0208] <Charge Generation Layer (CGL)> The charge generating layer generally contains a charge generating material (CGM) and a binder resin. The charge generating material (CGM) and the binder resin are the same as those explained in the above-mentioned single-layer type photosensitive layer.

[0209] (Other ingredients) The charge generating layer may contain other components as required in addition to the charge generating material and the binder resin. For example, in order to improve film forming properties, flexibility, coating properties, pollution resistance, gas resistance, light resistance, etc., known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, visible light shielding agents, fillers and other additives may be contained.

[0210] (Mixing ratio) In the charge generating layer, when the ratio of the charge generating material is too high, the stability of the coating liquid may be reduced due to the aggregation of the charge generating material, etc. On the other hand, when the ratio of the charge generating material is too low, it may lead to a decrease in sensitivity as a photoreceptor. Therefore, the mixing ratio (mass) of the binder resin and the charge generating material is preferably 10 parts by mass or more of the charge generating material per 100 parts by mass of the binder resin, and more preferably 30 parts by mass or more. On the other hand, it is preferably contained in a ratio of 1000 parts by mass or less, and more preferably in a ratio of 500 parts by mass or less. From the viewpoint of film strength, it is more preferably contained in a ratio of 300 parts by mass or less, and more preferably in a ratio of 200 parts by mass or less.

[0211] (Layer Thickness) The thickness of the charge generating layer is preferably 0.1 μm or more, more preferably 0.15 μm or more, and is preferably 10 μm or less, more preferably 0.6 μm or less.

[0212] <Charge Transport Layer (CTL)> The charge transport layer (CTL) generally contains a charge transport material and a binder resin. The charge transport material and the binder resin are the same as those explained in the above-mentioned single-layer type photosensitive layer.

[0213] In the charge transport layer (CTL), the ratio of the binder resin to the hole transport material (HTM) is preferably such that the hole transport material (HTM) is added in a ratio of 20 parts by mass or more relative to 100 parts by mass of the binder resin, wherein, from the viewpoint of reducing the residual potential, it is more preferably added in a ratio of 30 parts by mass or more, and further from the viewpoint of stability during repeated use and charge mobility, it is further preferably added in a ratio of 40 parts by mass or more. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is preferred that the hole transport material (HTM) is added in a ratio of 200 parts by mass or less relative to 100 parts by mass of the binder resin, and further from the viewpoint of compatibility of the hole transport material (HTM) with the binder resin, it is more preferably added in a ratio of 150 parts by mass or less, and from the viewpoint of glass transition temperature, it is particularly preferably added in a ratio of 120 parts by mass or less.

[0214] (Other ingredients) In addition to the electron transport material (ETM), the hole transport material (HTM) and the binder resin, the charge transport layer may contain other components as needed. For example, in order to improve film forming properties, flexibility, coating properties, pollution resistance, gas resistance, light resistance, etc., known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, visible light shielding agents, fillers and other additives may be contained.

[0215] (Layer Thickness) The thickness of the charge transport layer is not particularly limited. From the viewpoint of electrical properties, image stability, and further from the viewpoint of high resolution, it is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 35 μm or less, and even more preferably 15 μm or more and 25 μm or less.

[0216] <Method for Forming Photosensitive Layer> In either the laminated type or the single-layer type, the above-mentioned layers can be formed as follows. The formation can be carried out by repeating the coating / drying steps for each layer on a conductive support by a coating liquid obtained by dissolving or dispersing the contained substances in a solvent by a known method such as dip coating, spray coating, nozzle coating, bar coating, roll coating, and knife coating. However, the present invention is not limited to such a forming method.

[0217] The solvent or dispersing solvent used in the preparation of the coating liquid is not particularly limited. Specific examples include alcohols, ethers, aromatic hydrocarbons, chlorinated hydrocarbons, etc. In addition, they can be used alone or in any combination and type.

[0218] The amount of the solvent or dispersion medium used is not particularly limited, but is preferably appropriately adjusted in consideration of the purpose of each layer or the properties of the selected solvent / dispersion medium so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. The coating film is preferably dried by touch at room temperature, and then usually dried by heating at a temperature range of 30°C to 200°C for 1 minute to 2 hours, either statically or with air. The heating temperature may be constant or may be varied during drying.

[0219] <Conductive Support> The conductive support of the present electrophotographic photoreceptor (also referred to as "present conductive support") is not particularly limited as long as it can support the layer formed thereon and exhibit conductivity. As the conductive support, for example, mainly metal materials such as aluminum, aluminum alloy, stainless steel, copper, nickel, etc. can be used; resin materials that are given conductivity by allowing conductive powders such as metal, carbon, tin oxide, etc. to coexist; resins formed by evaporating or coating conductive materials such as aluminum, nickel, ITO (indium oxide tin oxide alloy) on the surface; glass, paper, etc. As the form of the conductive support, a support in the form of a drum, a cylinder, a sheet, a belt, or the like can be used. The conductive support of the present invention may be coated with a conductive material having an appropriate resistance value on the conductive support made of a metal material in order to control conductivity, surface properties, etc. or to cover defects.

[0220] When a metal material such as an aluminum alloy is used as the conductive support, the metal material may be used after an anodic oxide film is applied thereto.

[0221] The average film thickness of the anodized film is preferably 20 μm or less, and more preferably 7 μm or less.

[0222] When an anodic oxide film is formed on a metal material, it is preferable to perform a pore sealing treatment. The pore sealing treatment can be performed by a known method.

[0223] The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or performing a grinding treatment. Alternatively, the surface may be roughened by mixing particles of an appropriate particle size into the material constituting the support. In addition, a primer layer described below may be provided between the conductive support and the photosensitive layer in order to improve adhesiveness, adhesion, and the like.

[0224] <Base coating> The present electrophotographic photoreceptor may have an undercoat layer (also referred to as "undercoat layer") between the present photosensitive layer and the present conductive support.

[0225] As the base coat layer, for example, a resin or a material obtained by dispersing particles of an organic pigment or metal oxide in a resin can be used. Examples of organic pigments used in the undercoat layer include phthalocyanine pigments, azo pigments, perylene pigments, etc. Among them, phthalocyanine pigments and azo pigments are mentioned, and specifically, phthalocyanine pigments or azo pigments are mentioned when used as the above-mentioned charge generating material.

[0226] Examples of metal oxide particles used in the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, and iron oxide, and metal oxide particles containing multiple metal elements such as calcium titanate, strontium titanate, and barium titanate. The undercoat layer may use only one of the above particles, or may use a plurality of particles mixed in any ratio and combination.

[0227] Among the above-mentioned metal oxide particles, titanium oxide and aluminum oxide are preferred, and titanium oxide is particularly preferred.

[0228] The particle size of the metal oxide particles used in the primer layer is not particularly limited. From the perspective of the properties of the primer layer and the stability of the solution used to form the primer layer, the average primary particle size is preferably 10 nm or more, preferably 100 nm or less, and more preferably 50 nm or less.

[0229] As the binder resin used in the base coat, for example, the following resins can be selected and used: polyvinyl acetal resins such as polyvinyl butyral resins; insulating resins such as polyarylate resins, polycarbonate resins, polyester resins, phenoxy resins, acrylic resins, methacrylic resins, polyamide resins, polyurethane resins, epoxy resins, silicone resins, polyvinyl alcohol resins, styrene-alkyd resins, etc. However, it is not limited to these polymers. In addition, these binder resins can be used alone, or two or more can be mixed and used, and can also be used in a cured form together with a curing agent. Among them, polyvinyl acetal resins, alcohol-soluble copolymer polyamides, modified polyamides, etc. are preferred because they have good dispersibility and coating properties. Among them, alcohol-soluble copolymer polyamides are particularly preferred.

[0230] The mixing ratio of the particles to the binder resin may be arbitrarily selected, but is preferably used in a range of 10% by mass to 500% by mass in view of the stability and coating properties of the dispersion.

[0231] The film thickness of the undercoat layer can be arbitrarily selected. From the perspective of the characteristics of the electrophotographic photoreceptor and the coating properties of the dispersion, it is preferably 0.1 μm or more, and more preferably 20 μm or less. In addition, the undercoat layer may contain a known antioxidant or the like.

[0232] <Other layers> The present electrophotographic photoreceptor may further include other layers as required in addition to the present conductive support, the present photosensitive layer, the present protective layer and the undercoat layer.

[0233] <<Image Forming Apparatus>> The present electrophotographic photoreceptor can be used to constitute an image forming apparatus ("present image forming apparatus"). However, the present image forming apparatus described below is an example of an image forming apparatus that can be configured using the present electrophotographic photoreceptor, and is not limited to the present image forming apparatus.

[0234] like Figure 1 As shown, the image forming apparatus includes an electrophotographic photoreceptor 1, a charging device 2, an exposure device 3, and a developing device 4, and further includes a transfer device 5, a cleaning device 6, and a fixing device 7 as required. The present electrophotographic photoreceptor 1 is not particularly limited as long as it is the present electrophotographic photoreceptor described above. Figure 1 As an example, a drum-shaped photoreceptor having the above-mentioned photosensitive layer formed on the surface of a cylindrical conductive support is shown. Along the outer peripheral surface of the electrophotographic photoreceptor 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5 and a cleaning device 6 are arranged respectively.

[0235] As the charging device 2, there can be cited: a non-contact corona charging device such as a single-stage electrode wire (Corotron) or a grid-type electrode wire (Scorotron), or a contact charging device (direct charging device) that charges by bringing a charging component to which a voltage is applied into contact with the surface of the photoreceptor. Examples of contact charging devices include charging rollers, charging brushes, etc. It should be noted that Figure 1 In FIG. 1 , a roller-type charging device (charging roller) is shown as an example of the charging device 2 .

[0236] The exposure device 3 is not particularly limited in type as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1 . Alternatively, exposure may be performed by internal exposure of a photoreceptor. The light used for exposure is arbitrary.

[0237] The toner T may be of any type, and in addition to powdery toner, polymerized toner produced by a suspension polymerization method, an emulsion polymerization method, or the like may be used.

[0238] The structure of the developing device 4 is also arbitrary. Figure 1 The developing device 4 shown has a structure in which the toner T is thinned by a regulating member (developing blade) 45, frictionally charged to a predetermined polarity, and conveyed while being carried on a developing roller 44 to contact the surface of the photoreceptor 1. However, the present invention is not limited to this structure. The type of the transfer device 5 is not particularly limited, and a device using any method such as an electrostatic transfer method such as corona transfer, roller transfer, and belt transfer, a pressure transfer method, and an adhesive transfer method can be used.

[0239] The cleaning device 6 is not particularly limited. For example, any cleaning device such as a brush cleaner, a magnetic roller cleaner, or a blade cleaner may be used. When little or no toner remains on the surface of the photoreceptor, the cleaning device 6 may not be required. The fixing device 7 also has any structure. It should be noted that, in addition to the above-mentioned configuration, the image forming apparatus may also adopt a configuration capable of performing a static elimination process, for example.

[0240] In addition, the image forming apparatus may be further deformed in structure. For example, it may be configured to be capable of performing pre-exposure processes, auxiliary charging processes, etc., or to perform offset printing, or to be configured in a full-color tandem manner using a variety of colorants.

[0241] <<This electrophotographic photosensitive body cartridge>> The present electrophotographic photoreceptor 1 can be combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6 and the fixing device 7 to form an integrated box (referred to as "the present electrophotographic photoreceptor box"). However, the present electrophotographic photoreceptor cartridge described below is an example of an electrophotographic photoreceptor cartridge that can be configured using the present electrophotographic photoreceptor, and is not limited to the present electrophotographic photoreceptor cartridge.

[0242] The electrophotographic photosensitive body cartridge can be detachable from the main body of the electrophotographic device such as a copier or a laser printer. In this case, for example, when the electrophotographic photosensitive body 1 or other components are deteriorated, the maintenance / management of the image forming device is facilitated by removing the electrophotographic photosensitive body cartridge from the main body of the image forming device and installing another new electrophotographic photosensitive body cartridge on the main body of the image forming device.

[0243] <<Description of statement>> In the present invention, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, the expression "preferably" in this specification includes the meaning of "not necessarily, but preferably necessarily". In addition, the expression "even" in this specification means "and / or". Example

[0244] Hereinafter, the embodiments of the present invention will be further described in detail by way of example. However, the following embodiments are provided to illustrate the present invention in detail. As long as the present invention does not depart from its purport, the present invention is not limited to the embodiments shown below and can be arbitrarily deformed and implemented. In addition, as long as no particular provisions are made, the description of "parts" in the following embodiments and comparative examples indicates "parts by mass".

[0245] In the present specification, DMF refers to N,N-dimethylformamide, and MEHQ refers to 4-methoxyphenol.

[0246] <Synthesis of Electron Transporting Compounds> Next, the synthesis method of the electron transporting compounds 1 to 3 is described.

[0247] [Synthesis of Electron Transporting Compound 1] The synthesis scheme of the electron transporting compound 1 represented by the following structural formula is shown below.

[0248]

[0249]

[0250] The synthesis steps of the electron transporting compound 1 are as follows.

[0251] (Synthesis of Intermediate 1-1) Under nitrogen atmosphere, 100 mL of 1,4-dioxane was added to a mixture of succinic anhydride (11.0 g, 109.5 mmol) and 4-DMAP (4-dimethylaminopyridine, 0.26 g, 2.19 mmol) to prepare a solution. A mixed solution of glycerol dimethacrylate (25 g, 109.5 mmol) and MEHQ (27 mg, 0.22 mmol) dissolved in 50 mL of 1,4-dioxane was added dropwise to the solution, and stirred at 80°C for 9 hours. After cooling to room temperature, the solution was poured into 200 mL of water, extracted with dichloromethane, and the organic layer was washed with water and dried with magnesium sulfate. The obtained solid was filtered, the solvent of the filtrate was distilled off under reduced pressure, and the residue was dried to obtain intermediate 1-1 (yield 30 g, yield 83% by mass).

[0252] (Synthesis of Intermediate 1-2) Under nitrogen atmosphere, 100 mL of dehydrated dichloromethane and 1 mL of dehydrated dimethylformamide were added to intermediate 1-1 (21.6 g, 65.8 mmol), and the mixture was cooled on ice. Oxalyl chloride (11.2 mL, 131.6 mmol) was added dropwise, and the mixture was stirred for 2 hours under ice cooling and for 12 hours at room temperature. After the solvent was distilled off under reduced pressure, the residue was dried to obtain intermediate 1-2 (yield 21.5 g, yield 94% by mass).

[0253] (Synthesis of Intermediate 1-3) Under nitrogen atmosphere, 60 mL of N,N-dimethylformamide was added to naphthalene-1,4,5,8-tetracarboxylic dianhydride (7.18 g, 26.8 mmol) to prepare a solution. A mixed solution of L-(+)-leucinol (4.71 g, 40.2 mmol) and 2-ethylhexylamine (5.19 g, 40.2 mmol) dissolved in 40 mL of N,N-dimethylformamide was added dropwise to the solution and stirred at 120°C for 8 hours. After cooling to room temperature, the solution was poured into 200 mL of ice water, and 1N hydrochloric acid was added to make the reaction solution acidic. Extracted with dichloromethane, the organic layer was washed with water, dried with magnesium sulfate, and the solid obtained was filtered. The solvent of the filtrate was distilled off under reduced pressure, and the residue was dried to obtain intermediate 1-3 (yield 10.7 g, yield 84% by mass).

[0254] (Synthesis of Electron Transporting Compound 1) Under nitrogen atmosphere, 150 mL of dehydrated dichloromethane and triethylamine (11.7 mL, 84.4 mmol) were added to a mixture of intermediate 1-3 (10.1 g, 21.1 mmol) and 4-methoxyphenol (0.01 g) to prepare a solution, which was then ice-cooled. The intermediate 1-2 (14.6 g, 42.2 mmol) dissolved in 50 mL of dehydrated dichloromethane was added dropwise to the solution, stirred for 1 hour under ice-cooling, and stirred for 12 hours at room temperature. The reaction solution was injected into 100 mL of water, extracted with dichloromethane, and the organic layer was washed with water and dried over magnesium sulfate. The solid obtained was filtered, the solvent of the filtrate was distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography to obtain compound 1 (yield 5.3 g, yield 32% by mass).

[0255] [Synthesis of Electron Transporting Compound 2] The synthesis scheme of the electron transporting compound 2 represented by the following structural formula is shown below. It should be noted that the electron transporting compound 2 is a mixture of the electron transporting compound 2-a and the electron transporting compound 2-b.

[0256]

[0257]

[0258] The synthesis procedure of the electron transporting compound 2 is as follows.

[0259] (Synthesis of Intermediate 2-1) Under a nitrogen atmosphere, 100 mL of dehydrated dichloromethane was added to [2-(2-methoxyethoxy)ethoxy]acetic acid (6.3 g, 35.3 mmol) to prepare a solution, which was then ice-cooled. After 0.5 mL of N,N-dimethylformamide was added to the solution, oxalyl chloride (6.1 mL, 70.7 mmol) was added dropwise, and the mixture was stirred for 1 hour under ice-cooling and for 12 hours at room temperature. After the solvent was distilled off under reduced pressure, the residue was dried to obtain intermediate 2-1 (yield 6.9 g, yield 99% by mass).

[0260] (Synthesis of Intermediate 2-2) Under a nitrogen atmosphere, 3,4,9,10-perylenetetracarboxylic dianhydride (11.4 g, 29.0 mmol), zinc acetate (5.32 g, 29.0 mmol), imidazole 50 g and L-(+)-leucine alcohol (8.5 g, 72.5 mmol) were mixed and stirred at 160°C for 7 hours. After cooling to room temperature, the mixture was dissolved in dichloromethane, and the solution was poured into 200 mL of ice water. 1N hydrochloric acid was added to make the reaction solution acidic. The mixture was extracted with dichloromethane, and the organic layer was washed with water and dried over magnesium sulfate. The solid obtained was filtered, the solvent of the filtrate was distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography to obtain intermediate 2-2 (yield 12.0 g, yield 70% by mass).

[0261] (Synthesis of Electron Transporting Compound 2) Under a nitrogen atmosphere, 200 mL of dehydrated dichloromethane and triethylamine (19.5 mL, 141 mmol) were added to a mixture of intermediate 2-2 (13.9 g, 23.5 mmol) and 4-methoxyphenol (0.04 g) to prepare a solution, which was then ice-cooled. Intermediate 2-1 (12.2 g, 35.3 mmol) and intermediate 1-2 (6.94 g, 35.3 mmol) dissolved in 80 mL of dehydrated dichloromethane were added dropwise to the solution, stirred for 1 hour under ice-cooling and stirred for 12 hours at room temperature. The solvent of the reaction solution was distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography to obtain electron transport compound 2 (yield 22 g, yield 88% by mass, molar ratio of electron transport compound 2-a to electron transport compound 2-b 2-a:2-b=2:1).

[0262] [Synthesis of Electron Transporting Compound 3] The synthesis scheme of the electron transporting compound 3 represented by the following structural formula is shown below.

[0263]

[0264]

[0265] The synthesis steps of the electron transporting compound 3 are as follows.

[0266] (Synthesis of Intermediate 3-1) Under nitrogen atmosphere, 60 mL of dehydrated chloroform was added to 6-acetamidohexanoic acid (7.8 g, 45.0 mmol) to prepare a solution, and the solution was cooled on ice. Sulfonyl chloride (3.3 mL, 45.0 mmol) was added dropwise to the solution, and stirred for 30 minutes under ice cooling and for 1 hour at 60° C. After cooling to room temperature, the solvent was distilled off under reduced pressure, and the residue was dried to obtain intermediate 3-1 (yield 8.5 g, yield 98% by mass).

[0267] (Synthesis of Electron Transporting Compound 3) Under a nitrogen atmosphere, 60 mL of dehydrated dichloromethane and triethylamine (6.1 mL, 43.8 mmol) were added to the intermediate 2-2 (4.3 g, 7.3 mmol) to prepare a solution, which was cooled on ice. The intermediate 3-1 (4.2 g, 21.9 mmol) dissolved in 30 mL of dehydrated dichloromethane was added dropwise to the solution, stirred for 30 minutes under ice cooling, and stirred for 12 hours at room temperature. The solvent of the reaction solution was distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography to obtain an electron transport compound 3 (yield 2.5 g, yield 38% by mass).

[0268] <Electron Donating Compound 1> The electron donating compound 1 having a structure represented by the following structural formula (a product manufactured by Merck / Millipore Sigma) was used.

[0269]

[0270] <Electron Donating Compound 2> The electron donating compound 2 represented by the following structural formula was synthesized according to the method described in the Supplementary Information on page 2, line 18 to page 2, line 27 of the non-patent document (Mater. Chem. Front., 2020, 4, 3616).

[0271]

[0272] <Production of Electrophotographic Photoreceptor> (Preparation of coating solution P1 for forming undercoat layer) (Preparation of coating solution P1 for forming undercoat layer) 20 parts of D-type oxytitanium phthalocyanine showing a clear peak at a diffraction angle of 2θ=27.3°±0.2° in powder X-ray diffraction using CuKα rays were mixed with 280 parts of 1,2-dimethoxyethane, and pulverized for 2 hours with a sand mill for micronization and dispersion. 400 parts of a 1,2-dimethoxyethane solution containing 2.5% by mass of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Denka Butyral" #6000C) and 170 parts of 1,2-dimethoxyethane were further added and mixed to prepare a coating liquid P1 for forming an undercoat layer having a solid content concentration of 3.4% by mass.

[0273] (Preparation of single-layer photosensitive layer-forming coating solution Q1) 2.6 parts of D-type oxytitanium phthalocyanine showing a clear peak at a diffraction angle of 2θ=27.3°±0.2° in powder X-ray diffraction using CuKα rays, 1.3 parts of perylene pigment 1 having the following structure, 0.5 parts of polyvinyl butyral resin, 100 parts of the following hole transport material (HTM48, molecular weight 748), 60 parts of the following electron transport material (ET-2, molecular weight 424.2), 100 parts of a polycarbonate resin having a biphenyl structure, and 0.05 parts of silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd.: trade name KF-96) as a leveling agent were added to 793.35 parts of a mixed solvent (THF 80 mass %, TL 20 mass %) of tetrahydrofuran (hereinafter appropriately abbreviated as THF) and toluene (hereinafter appropriately abbreviated as TL) and mixed to prepare a single-layer photosensitive layer-forming coating liquid Q1 having a solid content concentration of 25 mass %.

[0274] Perylene Pigment 1

[0275]

[0276]

[0277] (Preparation of Protective Layer Forming Coating Liquid S1) A curable compound (polyester acrylate: ARONIX M-9050 manufactured by Toagosei Co., Ltd.) pre-dissolved in a mixed solvent of toluene / 2-propanol, Omnirad TPO H (2,4,6-trimethylbenzoyl-diphenylphosphine oxide) as a polymerization initiator and benzophenone (BP), an electron transporting compound 1, and an electron donating compound 1 are mixed to obtain a protective layer forming coating liquid S1 (solid content concentration of about 8% by mass) having a composition of electron transporting compound / M-9050 / electron donating compound / TPO+BP=100 / 50 / 2.5 / 9 (mass ratio) and a solvent composition of toluene / 2-propanol=3 / 7 (mass ratio).

[0278] (Preparation of coating solutions S2 to S16 for forming protective layer) Except that the type of the electron transport compound, the amount of the electron donating compound, the amount of the curable compound (M-9050) and the amount of the polymerization initiator are changed as shown in Table 1 and the solvent of S3 and S4 is further changed to a mixed solvent of THF / 2-propanol=3 / 7 (mass ratio), the coating liquids S2 to S16 for forming a protective layer are obtained in the same manner as the coating liquid S1 for forming a protective layer.

[0279] First, examples and comparative examples of the first and third embodiments of the present invention will be described.

[0280] <Production of Single-layer Photoreceptor> A single-layer photoreceptor was prepared by the following steps.

[0281] [Example 1-1] The coating liquid P1 for forming the undercoat layer is dip-coated on the surface of the cut On an aluminum cylinder 244 mm long, an undercoat layer was provided so that the film thickness after drying was 0.3 μm. The coating liquid Q1 for forming a single-layer photosensitive layer was dip-coated on the undercoat layer and dried at 100°C for 24 minutes to provide a single-layer photosensitive layer so that the film thickness after drying was 32 μm. The coating liquid S1 for forming a protective layer was ring-coated on the single-layer photosensitive layer, and immediately after coating, the photosensitive body was rotated at 60 rpm in a nitrogen atmosphere and heated at 0.9 W / cm 2 (108J / cm 2 ) for 2 minutes to provide a protective layer so that the thickness of the film after curing becomes 1.5 μm, thereby producing a photoreceptor A1-1.

[0282] [Examples 1-2 to 1-10 and Comparative Examples 1-1 to 1-7] Photoreceptors A1-2 to A1-16 were prepared in the same manner as in the photoreceptor A1-1 except that the protective layer forming coating liquid S1 was changed to the protective layer forming coating liquids S2 to S16.

[0283] <Electrical Characteristics: Evaluation of Residual Potential> The photoreceptors A1-1 to A1-16 obtained in the examples and comparative examples are installed on an electronic photography characteristic evaluation device made according to the measurement standards of the Society of Electronic Photography (described in "Fundamentals and Applications of Electronic Photography Technology", edited by the Society of Electronic Photography, Corona Company, pages 404-405), and the electrical characteristics based on the cycle of charging, exposure, potential measurement, and de-electrification are measured as follows. First, the grid voltage was adjusted so that the initial surface potential (V0) of the photoreceptor was charged to +700 V. Next, the photoreceptor was charged at 1.3 μJ / cm2 Exposure light was irradiated, and the residual potential (VL) was measured 60 milliseconds after the start of irradiation. It should be noted that the exposure light used was a halogen lamp light converted into 780 nm monochromatic light using an interference filter. The measurement environment was 25° C. and 50% relative humidity (N / N environment). The residual potential (VL) is shown in Table 1. The smaller the absolute value of the residual potential (VL), the more sufficient the charge is transferred and the lower the potential is, so it can be said that the result is better. In addition, the VL difference due to the presence or absence of the electron donating compound, that is, the result calculated by [(with electron donating compound; VL value of Example) - (without electron donating compound; VL value of Comparative Example)] is shown in Table 1. When the VL difference is a negative value, it can be said that the VL value is reduced by containing the electron donating compound, that is, the electrical characteristics are improved. In the first and third embodiments of the present invention, a case where the VL difference is a negative value smaller than -1 is evaluated as "acceptable".

[0284] <Evaluation of Potential Retention Rate> The photoreceptors A1-1 to A1-16 obtained in Examples and Comparative Examples were mounted on the above-mentioned electrophotographic characteristic evaluation apparatus, and the potential retention rate based on the cycle of charging, exposure, potential measurement, and charge elimination was measured as follows. As an evaluation of electrical properties, the potential retention rate (%) after charging at +700 V and leaving for 5 seconds was measured. The measurement was carried out at a temperature of 25° C. and a relative humidity of 50% (N / N environment). The potential retention rate is shown in Table 1. The potential retention rate indicates the retention rate (%) of the surface potential when the surface-charged photoreceptor is left for a certain period of time. The larger the surface potential retention rate (%), the better the potential is maintained even after a certain period of time, and the better the charging property is, so it can be said that the result is better.

[0285] <Determination of Martens hardness and elastic deformation rate> The photoreceptors A1-1 to A1-16 obtained in Examples and Comparative Examples were measured from the surface side of the photoreceptor using a microhardness tester (manufactured by Fischer: FISCHERSCOPE HM2000) at a temperature of 25° C. and a relative humidity of 50% under the following measurement conditions.

[0286] [Measurement conditions of Martens hardness and elastic deformation rate] Indenter: Vickers square pyramid diamond indenter with an opposite angle of 136° Maximum pressing load: 0.2mN Time required for loading: 10 seconds Time required to uninstall: 10 seconds The Martens hardness is calculated by the following formula. Martens hardness (N / mm 2 ) = Maximum indentation load / Depression area at maximum indentation load The elastic deformation rate is a value defined by the following formula, which is the ratio of the work performed by the film due to elasticity when unloaded to the total work required for pressing. Elastic deformation rate (%) = (We / Wt) × 100 In the above formula, the total work Wt (nJ) is expressed by Figure 2 The area enclosed by ABDA in the figure, and the elastic deformation work We (nJ) represents the area enclosed by CBDC. The larger the elastic deformation rate, the less likely it is that the deformation will remain relative to the load. When the elastic deformation rate is 100, no deformation will remain.

[0287] [Table 1]

[0288] <Inspection> From the results in Table 1, it was confirmed that the residual potential (VL) of Example 1-1 was 62 V lower than that of Comparative Example 1-1 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 1-2 was 115 V lower than that of Comparative Example 1-2 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 1-3 was 56 V lower than that of Comparative Example 1-3 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 1-4 was 33 V lower than that of Comparative Example 1-4 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 1-5 was 32 V lower than that of Comparative Example 1-5 due to the addition of the electron donating compound (dopant). Furthermore, it was confirmed that the residual potential (VL) of Example 1-6 was 38 V lower than that of Comparative Example 1-6 due to the addition of the electron donating compound (dopant). Furthermore, it was confirmed that the residual potentials (VL) of Examples 1-8, 1-9, and 1-10 were 35 V, 66 V, and 3 V lower than those of Comparative Example 1-1, respectively, due to the addition of the electron donating compound (dopant). It can be seen from this that when an electron-donating compound is added to the protective layer, the electrical properties of the electrophotographic photoreceptor, especially the residual potential properties, can be further improved. This is speculated as follows: when the electron-donating compound is present in the protective layer, the electron-transporting compound becomes more likely to accept electrons through the electrons supplied to the electron-donating compound, and the electron transport performance of the electron-transporting compound is further improved, which can further improve the electron injection or electron transport performance to the protective layer, and as a result, the electrical properties of the electrophotographic photoreceptor, especially the residual potential properties, can be further improved. Furthermore, from the above results, it can be seen that even if the protective layer contains an electron donating compound, the potential retention rate, hardness, and elastic deformation rate remain unchanged and are good.

[0289] Next, examples and comparative examples of the second embodiment of the present invention will be described.

[0290] <Production of Single-layer Photoreceptor> A single-layer photoreceptor was prepared by the following steps.

[0290] [Example 2-1] A photoreceptor A2-1 was prepared in the same manner as in Example 1-1.

[0292] [Examples 2-2 to 2-9 and Comparative Examples 2-1 to 2-8] Photoreceptors A2-2 to A2-16 were prepared in the same manner as in the photoreceptor A2-1 except that the protective layer forming coating liquid S1 was changed to the protective layer forming coating liquids S2 to S16.

[0293] <Electrical Characteristics: Evaluation of Residual Potential> The residual potential (VL) of the photoreceptors A2-1 to A2-16 obtained in Examples and Comparative Examples was measured by the above-mentioned method. In addition, the VL difference caused by the presence or absence of the electron-donating compound, that is, the result calculated by [(with electron-donating compound; VL value of the embodiment)-(without electron-donating compound; VL value of the comparative example)] is shown in Table 3. When the VL difference is a negative value, it can be said that the VL value is reduced by containing the electron-donating compound, that is, the electrical characteristics become good. In the second embodiment of the present invention, the case where the VL difference is less than a negative value of -10 is evaluated as "acceptable".

[0294] <Evaluation of Potential Retention Rate> The potential retention (%) of the photoreceptors A2-1 to A2-16 obtained in Examples and Comparative Examples was measured by the above-mentioned method. The measurement results are shown in Table 2.

[0295] <Determination of Martens hardness and elastic deformation rate> The photoreceptors A2-1 to A2-16 obtained in the examples and comparative examples were measured for Martens hardness (N / mm 2 The results are shown in Table 2.

[0296] [Table 2]

[0297] <Inspection> From the results in Table 1, it was confirmed that the residual potential (VL) of Example 2-1 was 62 V lower than that of Comparative Example 2-1 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 2-2 was 115 V lower than that of Comparative Example 2-2 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 2-3 was 56 V lower than that of Comparative Example 2-3 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 2-4 was 33 V lower than that of Comparative Example 2-4 due to the addition of the electron donating compound (dopant). It was confirmed that the residual potential (VL) of Example 2-5 was 32 V lower than that of Comparative Example 2-5 due to the addition of the electron donating compound (dopant). Furthermore, it was confirmed that the residual potential (VL) of Example 2-6 was 38 V lower than that of Comparative Example 2-6 due to the addition of the electron donating compound (dopant). Furthermore, it was confirmed that the residual potentials (VL) of Examples 2-8 and 2-9 were 35 V and 66 V lower than that of Comparative Example 2-1, respectively, due to the addition of the electron donating compound (dopant). It can be seen from this that when an electron-donating compound is added to the protective layer, the electrical properties of the electrophotographic photoreceptor, especially the residual potential properties, can be further improved. This is speculated as follows: when the electron-donating compound is present in the protective layer, the electron-transporting compound becomes more likely to accept electrons through the electrons supplied to the electron-donating compound, and the electron transport performance of the electron-transporting compound is further improved, which can further improve the electron injection or electron transport performance to the protective layer, and as a result, the electrical properties of the electrophotographic photoreceptor, especially the residual potential properties, can be further improved. Furthermore, from the above results, it can be seen that even if the protective layer contains an electron donating compound, the potential retention rate, hardness, and elastic deformation rate remain unchanged and are good.

Claims

1. An electrophotographic photoreceptor, comprising at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron-donating compound and a cured product formed by curing a photocurable compound. The electron donating compound is a compound having a benzimidazole structure or a guanidine structure.

2. An electrophotographic photoreceptor, which is an electrophotographic photoreceptor having at least a photosensitive layer and a protective layer in sequence on a conductive support, wherein: The protective layer contains an electron-donating compound, The electron donating compound is a compound having a benzimidazole structure or a guanidine structure, The content of the electron donating compound in the protective layer is 0.62 parts by mass or more relative to 100 parts by mass of the total mass of the protective layer.

3. An electrophotographic photoreceptor, comprising at least a photosensitive layer and a protective layer in this order on a conductive support, wherein: The protective layer contains an electron donating compound and an electron transporting compound, The content mass ratio of the electron donating compound to the electron transporting compound is 0.001 or more and 0.8 or less.

4. The electrophotographic photoreceptor according to claim 3, wherein The electron donating compound is a compound having two or more nitrogen atoms in a molecule.

5. The electrophotographic photoreceptor according to claim 3 or 4, wherein The electron donating compound is a compound having a benzimidazole structure or a guanidine structure.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The electron donating compound is an electron donating compound represented by the following formula (2) or the following formula (3), In the above formula (2), E 1 ~E 4 each independently represents a hydrogen atom, a halogen atom, an alkyl group which may be substituted, an alkylthio group which may be substituted, an arylthio group which may be substituted, an arylsulfonyl group which may be substituted, an amino group which may be substituted, an alkylamino group which may be substituted, an arylamino group which may be substituted, a hydroxyl group which may be substituted, an alkoxy group which may be substituted, an amide group which may be substituted, an acyloxy group which may be substituted, an aromatic hydrocarbon group which may be substituted, a carboxyl group which may be substituted, a carboxamide group which may be substituted, a carbonyl alkoxy group which may be substituted, an acyl group which may be substituted, a sulfonyl group which may be substituted, a cyano group which may be substituted, or a nitro group which may be substituted, or a derivative of any of them; in addition, E 1 ~E 4 are bonded to each other to form a ring or not; h is an integer greater than 0, In formula (3), Ar T1 According to the above formula (4), G 1 is a hydrocarbon group which may have a substituent, g1 is an integer greater than 1, In formula (4), * represents the same as G in formula (3). 1 Bonding, G 2 It is an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a halogen atom, and g2 is an integer greater than or equal to 0.

7. The electrophotographic photoreceptor according to claim 6, wherein The electron donating compound is at least one selected from the group consisting of compounds represented by the following formula:

8. The electrophotographic photoreceptor according to claim 1 or 2, wherein The protective layer further contains an electron transporting compound.

9. The electrophotographic photoreceptor according to claim 8, wherein The content mass ratio of the electron donating compound to the electron transporting compound is 0.001 or more and 1.0 or less.

10. The electrophotographic photoreceptor according to any one of claims 3 to 5, 8 and 9, wherein The electron transporting compound is an electron transporting compound represented by the following formula (1), In formula (1), X represents an electron transport skeleton; R1 and R2 each independently represent a hydrogen atom or an alkyl group which may be substituted, an alkoxy group which may be substituted, an aryloxy group which may be substituted, a heteroaryloxy group which may be substituted, an alkoxycarbonyl group which may be substituted, a dialkylamino group which may be substituted, a diarylamino group which may be substituted, an arylalkylamino group which may be substituted, an acyl group which may be substituted, a haloalkyl group which may be substituted, an alkylthio group which may be substituted, an arylthio group which may be substituted, or a thioalkyl group which may be substituted. wherein the present invention further comprises a substituted silyl group, a substituted or unsubstituted silyloxy group, an aromatic hydrocarbon group which may be substituted or an aromatic heterocyclic group which may be substituted; L1 represents a divalent group; Z1 represents a hydrogen atom, an alkoxy group, an amide group (-NHCO-R'), an acrylamide group, a methacrylamide group, an acryloyl group or a methacryl group; the R' represents a hydrogen atom, an alkyl group which may be substituted or an aralkyl group which may be substituted or an aromatic group which may be substituted; a represents an integer greater than 1; when a is an integer greater than 2, R1, R2, L1 and Z1 in the repeating structure are respectively the same as or different from each other.

11. The electrophotographic photoreceptor according to claim 10, wherein The structure in which X in the formula (1) is substituted with a hydrogen atom at its bonding site is a structure selected from the group consisting of the following formulae (A-1) to (A-13): In formulas (A-1) to (A-13), P1 to P 21 Each independently represents a hydrogen atom or an alkyl group which may be substituted, an aralkyl group which may be substituted, an aromatic group which may be substituted, an alkoxy group which may be substituted, an aryloxy group which may be substituted, an acyl group which may be substituted, an ester group which may be substituted, a cyano group which may be substituted, a nitro group which may be substituted, a sulfone group which may be substituted, a hydroxyl group which may be substituted, an aldehyde group which may be substituted, or a halogen atom; m1 to m10 each independently represent an integer greater than 0; when m1 to m10 are each an integer greater than 2, P6 to P6 in the repeating structure are 15 are the same or different from each other; Q1~Q 24 each independently represents an oxygen atom, a sulfur atom, C(CN)2, CR"CN, CA2, C(COOR")2, CR"COOR", NR" or NCR", wherein A represents a halogen atom, and R" represents a hydrogen atom or an alkyl group which may be substituted, an alkoxy group which may be substituted, an aryloxy group which may be substituted, a heteroaryloxy group which may be substituted, an alkoxycarbonyl group which may be substituted, a dialkylamino group which may be substituted, a diarylamino group which may be substituted, an arylalkylamino group which may be substituted, an acyl group which may be substituted, a haloalkyl group which may be substituted, an alkylthio group which may be substituted, an arylthio group which may be substituted, a silyl group which may be substituted, a silyloxy group which may be substituted, an aromatic hydrocarbon group which may be substituted, or an aromatic heterocyclic group which may be substituted; Ar1 ​​to Ar 19 Each independently represents an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent.

12. The electrophotographic photoreceptor according to claim 10 or 11, wherein The structure in which X in the formula (1) is substituted with a hydrogen atom at its bonding site is a structure selected from the group consisting of the following formulae (B-1) to (B-38): In formulas (B-1) to (B-38), P1 to P 21 Each independently represents a hydrogen atom or an alkyl group which may be substituted, an aralkyl group which may be substituted, an aromatic group which may be substituted, an alkoxy group which may be substituted, an aryloxy group which may be substituted, an acyl group which may be substituted, an ester group which may be substituted, a cyano group which may be substituted, a nitro group which may be substituted, a sulfone group which may be substituted, a hydroxyl group which may be substituted, an aldehyde group which may be substituted, or a halogen atom; m1 to m10 each independently represent an integer greater than 0; when m1 to m10 are each an integer greater than 2, P6 to P6 in the repeating structure are 15 The same as or different from each other.

13. The electrophotographic photoreceptor according to any one of claims 10 to 12, wherein In the formula (1), L1 is an alkylene group, a divalent group having a keto group, a divalent group having an ether bond, a divalent group having an ester bond, or a group formed by connecting these groups.

14. An electrophotographic photosensitive body cartridge, characterized in that: The present invention comprises the electrophotographic photoreceptor according to any one of claims 1 to 13.

15. An image forming device, characterized in that: The present invention comprises the electrophotographic photoreceptor according to any one of claims 1 to 13.

Images