Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus

Abstract

Provided is a new electrophotographic photoreceptor which has a high photoreceptor surface hardness and with which it is possible to suppress the formation of a mixed layer between a photosensitive layer and a protective layer to prevent deterioration of electrical characteristics.　An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer in the stated order on an electroconductive support, wherein the protective layer contains a polymer having a structure represented by the following formula (1) or (2).　[Formula (1)] (In formula (1), l, m, n, and o are each integers of 0-10 inclusive, and l+m+n+o is 1 or greater. Each R independently represents a divalent group selected from C1-C8 alkylene groups, C1-C8 oxyalkylene groups, and −O−(C=O)−(CH2)p− (where p is 2-6 inclusive). T represents a bond with any atom. Q represents a hydroxy group or the following formula (3). Each Z1 independently represents a hydrogen atom or a C1-C4 alkyl group, at least one being a C1-C4 alkyl group.)　[Formula (2)] (In formula (2), f, g, h, i, j, and k are integers of 0-10 inclusive, and f+g+h+i+j+k is 1 or greater. Each R independently represents a divalent group selected from C1-C8 alkylene groups, C1-C8 oxyalkylene groups, and −O−(C=O)−(CH2)p− (where p is 2-6 inclusive). T represents a bond with any atom. Q represents a hydroxy group or the following formula (3). Each Z1 independently represents a hydrogen atom or a C1-C4 alkyl group, at least one being a C1-C4 alkyl group.)　[Formula (3)] (In formula (3), Z2 represents a bond with R in formula (1) or (2). Z1 represents a hydrogen atom or a C1-C4 alkyl group. T represents a bond with any atom.)

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 same, and an image forming apparatus.

Background Art

[0002] In printers, copiers, etc., when light is irradiated onto a charged organic photoreceptor (OPC) drum, the irradiated portion is discharged and an electrostatic latent image is formed. By attaching toner to the electrostatic latent image, an image can be obtained. In such devices using electrophotographic technology, the photoreceptor is a core member.

[0003] For this type of organic photoreceptor, since there is a large margin in material selection and it is easy to control the characteristics of the photoreceptor, a "function-separated photoreceptor" that distributes the functions of charge generation and movement to different compounds has become the mainstream. For example, a single-layer electrophotographic photoreceptor (hereinafter referred to as a single-layer photoreceptor) having a charge generation material (CGM) and a charge transport material (CTM) in the same layer, and a laminated electrophotographic photoreceptor (hereinafter referred to as a laminated photoreceptor) formed by laminating a charge generation layer containing a charge generation material (CGM) and a charge transport layer containing a charge transport material (CTM) are known. Further, as the charging method of the photoreceptor, a negative charging method for charging the surface of the photoreceptor with a negative charge and a positive charging method for charging the surface of the photoreceptor with a positive charge can be mentioned. As combinations of the layer structure and charging method of currently commercialized photoreceptors, a "negatively charged laminated photoreceptor" and a "positively charged single-layer photoreceptor" can be mentioned.

[0004] A "negatively charged laminated photoreceptor" generally has a structure in which an undercoat layer (UCL) made of resin or the like is provided on a conductive substrate such as an aluminum tube, a charge generation layer (CGL) made of a charge generation material (CGM) and resin or the like is provided thereon, and further a charge transport layer (CTL) made of a hole transport material (HTM) and resin or the like is provided thereon.

[0005] On the one hand, a "positively charged single-layer photoreceptor" generally has a structure in which an undercoat layer (UCL) made of resin or the like is provided on a conductive substrate such as an aluminum tube, and a single-layer photosensitive layer made of a charge generating material (CGM), a hole transporting material (HTM), an electron transporting material (ETM), and resin or the like is provided thereon (see, for example, Patent Document 1).

[0006] In any photoreceptor, after the surface of the photoreceptor is charged by a corona discharge method or a contact method, the photoreceptor is exposed to neutralize the surface charges, thereby forming an electrostatic latent image due to the potential difference with the surrounding surface. Then, toner is brought into contact with the surface of the photoreceptor to form a toner image corresponding to the electrostatic latent image, and this is transferred to paper or the like and heat-fused and fixed to complete printing.

[0007] As described above, the basic structure of an electrophotographic photoreceptor is a photosensitive layer formed on a conductive support, but for the purpose of improving wear resistance and the like, a protective layer is also provided on the photosensitive layer.

[0008] As a technique for improving the mechanical strength or wear resistance of the photoreceptor surface, a photoreceptor is disclosed in which a layer containing a compound having a chain-polymerizable functional group is formed as the outermost layer of the photoreceptor, and this is polymerized by applying energy such as heat, light, radiation, etc. to form a cured resin layer (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] As mentioned above, a method for improving the mechanical strength or abrasion resistance of the photoreceptor surface is known, which involves forming a protective layer using a polyfunctional acrylate or polyfunctional methacrylate as a curable resin. However, when a protective layer is formed using certain polyfunctional acrylates or polyfunctional methacrylates, the electrical properties deteriorate, and a tendency for residual charge to remain after exposure is observed. For example, trimethylolpropane trimethacrylate (TMPT) is relatively easy to obtain, and because it has a small molecular weight and low functional group equivalent, it can be crosslinked densely in three dimensions and is known as a material with excellent mechanical strength. For this reason, TMPT is a well-known material as a (meth)acrylate material for forming protective layers. However, when a protective layer is formed using certain polyfunctional acrylates or polyfunctional methacrylates, such as TMPT, a tendency for residual potential properties to deteriorate, resulting in residual charge after exposure, is observed. Furthermore, printers and copiers have built-in chargers for charging the photoreceptor, and when charging, acidic gases such as ozone are generated from the charger. When these acidic gases penetrate the protective layer, the gas resistance tends to deteriorate depending on the material forming the protective layer.

[0011] The object of the present invention is to provide a novel electrophotographic photoreceptor having a photosensitive layer and a protective layer sequentially provided on a conductive support, which has high Martens hardness and elastic deformation rate on the surface of the photoreceptor, while preventing deterioration of electrical properties, such as residual potential properties, and also having good gas resistance. [Means for solving the problem]

[0012] The present invention solves the above problems by forming a protective layer using a compound having a specific structure among polyfunctional acrylates or polyfunctional methacrylates. In other words, the gist of the present invention is found in the following [1] to

[11] .

[0013] [1] An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, wherein the protective layer contains a polymer having a structure represented by the following formula (1) or (2).

[0014] [Formula (1)] TIFF0007896636000001.tif52170

[0015] In formula (1), l, m, n, and o are integers between 0 and 10, and l+m+n+o is 1 or greater. R is independently an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) represents a divalent group. T represents a bond with any atom. Q represents a hydroxyl group or formula (3) below. Z 1 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms.

[0016] [Formula (2)] TIFF0007896636000002.tif46170

[0017] In equation (2), f, g, h, i, j, and k are integers between 0 and 10, and f+g+h+i+j+k is 1 or greater. R is independently an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) represents a divalent group. T represents a bond with any atom. Q represents a hydroxyl group or formula (3) below. Z 1 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms.

[0018] [Formula (3)] TIFF0007896636000003.tif33170

[0019] In formula (3), Z 2 represents the bond with R in equation (1) or (2). Z 1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. T represents a bond with any atom.

[0020] [2] The electrophotographic photoreceptor according to [1], wherein the protective layer contains a polymer having the structure represented by formula (1) above.

[0021] [3] An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, wherein the protective layer contains a polymer of compound a having a structure represented by the following formula (1') or a polymer of compound b having a structure represented by the following formula (2').

[0022] [Formula (1')] TIFF0007896636000004.tif53170

[0023] In formula (1'), l, m, n, and o are integers between 0 and 10, and l+m+n+o is 1 or greater. R is independently an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) represents a divalent group. Q represents a hydroxyl group or the following formula (3'). Z 1 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms.

[0024] [Formula (2')] TIFF0007896636000005.tif50170

[0025] In formula (2'), f, g, h, i, j, and k are integers between 0 and 10, and f+g+h+i+j+k is 1 or greater. R is independently an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2)p -(provided that p represents a divalent group selected from among (where p is 2 or more and 6 or less)). Q represents a hydroxy group or the following formula (3’). Z 1 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of them is an alkyl group having 1 to 4 carbon atoms.

[0026] [Formula (3’)] TIFF0007896636000006.tif29170

[0027] In formula (3’), Z 2 represents a bond with R in formula (1’) or formula (2’). Z 1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0028] [4] An electrophotographic photoreceptor sequentially provided with a photosensitive layer and a protective layer on a conductive support, where the protective layer contains a polymer of a compound a having a structure represented by the above formula (1’), which is the electrophotographic photoreceptor according to [3].

[0029] [5] The electrophotographic photoreceptor according to any one of [1] to [4], wherein R in formula (1), formula (2), formula (1’) or formula (2’) is an oxyalkylene group having 1 to 8 carbon atoms.

[0030] [6] The electrophotographic photoreceptor according to any one of [1] to [5], wherein the protective layer contains metal oxide particles. [7] The electrophotographic photoreceptor according to any one of [1] to [6], wherein the protective layer is a layer cured by irradiation with ultraviolet light or / and visible light. [8] The electrophotographic photoreceptor according to any one of [1] to [7], wherein the photosensitive layer is a single-layer type photosensitive layer containing both a charge generating substance and a charge transporting substance in the same layer.

[0031] [9] The electrophotographic photoreceptor according to [3] or [4], characterized in that the molecular weight X of compounds a and b represented by either formula (1') or (2') and the number Y of acryloyl groups and methacryloyl groups contained in one molecule satisfy the following formula (4). 120 ≤ X / Y ≤ 400 (4)

[0032]

[10] The electrophotographic photoreceptor according to [3] or [4], wherein the molecular weights of compounds a and b represented by either formula (1') or (2') are 550 or more and 1400 or less.

[11] An electrophotographic photoreceptor according to any one of [1] to

[10] , wherein l, m, n, and o in formula (1) or formula (1') are each integers between 0 and 8.

[12] An electrophotographic photoreceptor according to any one of [1] to

[11] , wherein l+m+n+o in formula (1) or formula (1') is 1 or more and 12 or less.

[13] An electrophotographic photoreceptor according to any one of [1] to

[12] , wherein f+g+h+i+j+k in formula (2) or formula (2') is 1 or more and 18 or less.

[0033]

[14] An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, An electrophotographic photoreceptor comprising a polymer having a group represented by R' below, a structure represented by formula (5) below, and a structure represented by formula (6) below, wherein the protective layer contains a polymer. R': Alkylene group with 1 to 8 carbon atoms, oxyalkylene group with 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - A divalent group selected from (where p is between 2 and 6)

[0034] [Formula (5)] JPEG0007896636000007.jpg32158

[0035] In formula (5), Z 3 This represents a bond with any atom.

[0036] [Formula (6)] JPEG0007896636000008.jpg34166

[0037] In formula (6), Z 4 represents an alkyl group with 1 to 4 carbon atoms. T represents a bond with any atom.

[0038]

[15] An electrophotographic photoreceptor cartridge having an electrophotographic photoreceptor as described in any one of [1] to

[14] .

[16] An image forming apparatus having an electrophotographic photoreceptor as described in any one of [1] to

[14] . [Effects of the Invention]

[0039] The electrophotographic photoreceptor of the present invention has high Martens hardness and elastic deformation rate on the surface of the photoreceptor, while preventing deterioration of electrical properties, such as deterioration of residual potential properties where charge remains after exposure, and also exhibits good gas resistance. [Brief explanation of the drawing]

[0040] [Figure 1] This figure schematically shows an example of the configuration of an image forming apparatus that can be constructed using an electrophotographic photoreceptor according to an example of the present invention. [Figure 2] This graph shows the general relationship between the indentation depth of the indenter and the load curve when measuring the Martens hardness and elastic deformation rate of a photoreceptor. [Modes for carrying out the invention]

[0041] The embodiments for carrying out the present invention (hereinafter referred to as "embodiments of the invention") will be described in detail below. However, the present invention is not limited to the following embodiments and can be implemented in various ways within the scope of its essence.

[0042] <<This electrophotographic light conductor>> An example of an embodiment of the present invention (also referred to as "this electrophotographic photoreceptor") is an electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, wherein the protective layer preferably contains a cured product obtained by curing a curable compound.

[0043] This electrophotographic photoreceptor may optionally have layers other than the photosensitive layer and the protective layer. Furthermore, the charging method for this electrophotographic photoreceptor may be either a negative charging method, which charges the surface of the photoreceptor with a negative charge, or a positive charging method, which charges the surface of the photoreceptor with a positive charge.

[0044] In this electrophotographic photoreceptor, the side opposite to the conductive support is the upper side or front side, and the side with the conductive support is the lower side or back side. From the viewpoint of obtaining the effects of the present invention to the fullest, it is preferable that the protective layer is the outermost layer.

[0045] <Main protective layer> The protective layer of this electrophotographic photoreceptor (also referred to as "this protective layer") is preferably a layer containing polymer A having a structure represented by the following formula (1) or polymer B having a structure represented by the following formula (2).

[0046] [Formula (1)] TIFF0007896636000009.tif52170

[0047] [Formula (2)] TIFF0007896636000010.tif46170

[0048] The protective layer is also preferably a layer containing polymer A' of compound a having the structure represented by the following formula (1'), or polymer B' of compound b having the structure represented by the following formula (2'). In other words, the protective layer contains a cured product obtained by curing a curable compound, and the curable compound is preferably a compound having the structure represented by the following formula (1'), or a compound having the structure represented by the following formula (2').

[0049] [Formula (1')] TIFF0007896636000011.tif53170

[0050] [Formula (2')] TIFF0007896636000012.tif50170

[0051] As mentioned above, when a protective layer is formed using trimethylolpropane trimethacrylate (TMPT), a tendency for residual potential characteristics, where charge remains after exposure, to deteriorate was observed. The inventors speculate on the cause of this as follows: The alkyl side chains in the molecule of TMPT have a nonpolar structure. On the other hand, the binder resin, hole transport material, electron transport material, etc., which are the main components of the photosensitive layer, also have relatively nonpolar structures. Therefore, TMPT has a high affinity for the photosensitive layer, and when a protective layer is formed using TMPT, for example, when a protective layer forming solution is applied to the surface of the photosensitive layer and heated and dried, or when it is subsequently cured, a layer (mixed layer) in which the components of both layers are mixed is easily formed between the protective layer and the photosensitive layer. It is thought that this mixed layer inhibits charge transport from the photosensitive layer to the protective layer, thus deteriorating the electrical properties, especially the residual potential characteristics. In contrast, the structures represented by formulas (1), (2), (1'), or (2') do not have low-polarity side chains such as alkyl groups, and furthermore, they have structures in which groups with relatively high polarity C=O bonds (e.g., acryloyl groups, methacryloyl groups) or hydroxyl groups are located on the outside of the molecule. These polar groups located on the outside have poor affinity with the relatively low-polarity photosensitive layer. Therefore, when forming this protective layer, especially when applying the protective layer forming coating solution to the photosensitive layer surface and heating and drying it, it is possible to suppress the formation of a mixed layer between the protective layer and the photosensitive layer, and as a result, it is thought that deterioration of electrical properties, particularly deterioration of residual potential properties, can be prevented. Furthermore, the structure represented by equation (1), equation (2), equation (1'), or equation (2') is at least one Z 1 This is an alkyl group with 1 to 4 carbon atoms. As a result, acidic gases such as ozone generated inside the printer are Z 1Because it sterically inhibits the approach of the unreacted carbon-carbon double bond to which it is bonded, it is thought that oxidative degradation of the carbon-carbon double bond can be suppressed, resulting in good gas resistance.

[0052] [Equation (1) and Equation (1')] In formulas (1) and (1') above, l, m, n, and o are integers between 0 and 10, inclusive. Preferably, they are integers of 1 or greater, more preferably 8 or less, more preferably 4 or less, and even more preferably 2 or less. l+m+n+o represents the equivalent amount of the linking chain R contained in formula (1) and formula (1') above. A value of 1 or more is preferable from the viewpoint of suppressing steric repulsion between groups having C=O bonds (e.g., (meth)acryloyl groups) located at the terminal end of the molecule and preventing the elimination of C=O bonded groups (e.g., (meth)acryloyl groups), and a value of 2 or more is even more preferable. On the other hand, a value of 20 or less is preferable from the viewpoint of the mechanical strength of the protective layer, a value of 12 or less is more preferable, a value of 6 or less is even more preferable, and a value of 4 or less is particularly preferable.

[0053] In formulas (1) and (1') above, the presence of the linking chain R suppresses steric repulsion between groups having C=O bonds (e.g., (meth)acryloyl groups) located at the terminal end of the molecule, and prevents the elimination of groups having C=O bonds (e.g., (meth)acryloyl groups). From this viewpoint, R is independently an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) is a divalent group selected from among these. Among these, an oxyalkylene group having 1 to 8 carbon atoms is preferred from the viewpoint of ease of synthesis. Examples of oxyalkylene groups having 1 to 8 carbon atoms include -O-CH2-, -O-CH2-CH2-, -O-CH(CH3)-CH2-, -O-CH2-CH(CH3)-, -O-CH2-CH2-CH2-, and -O-CH2-CH2-CH2-CH2-. Among these, -O-CH2-CH2- and -O-CH(CH3)-CH2- are preferred, and -O-CH2-CH2- is more preferred. When the linking chain R is an oxyalkylene group having 1 to 8 carbon atoms, the number of oxyalkylene groups in one molecule of compound a having the structure represented by formula (1') is preferably 2 or more, more preferably 4 or more. On the other hand, it is preferably 12 or less, more preferably 10 or less, and even more preferably 6 or less.

[0054] In equation (1) above, T represents a bond with any atom. Examples of such atoms include carbon, hydrogen, nitrogen, and oxygen.

[0055] In formula (1) above, Q is preferably a hydroxyl group or the following formula (3) from the viewpoint of having polarity and suppressing the formation of a mixed layer. Furthermore, Q in formula (1') above is preferably a hydroxyl group or formula (3') below, from the viewpoint of having polarity and suppressing the formation of a mixed layer.

[0056] In equations (1) and (1') above, Z 1 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and preferably at least one of them is an alkyl group having 1 to 4 carbon atoms. In formulas (1) and (1') above, Z 1 It is more preferable that two or more of them are alkyl groups having 1 to 4 carbon atoms, and even more preferable that three or more of them are alkyl groups having 1 to 4 carbon atoms, and all Z 1 It is particularly preferable that the alkyl group has 1 to 4 carbon atoms. 1 If the alkyl group has 1 to 4 carbon atoms, then acidic gases such as ozone will react to Z 1 Because it sterically inhibits the approach of the unreacted carbon-carbon double bond to which it is bonded, it has good gas resistance. Also, Z in equations (1) and (1') 1 When is an alkyl group having 1 to 4 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, i.e., a methyl group.

[0057] [Equations (2) and (2')] In equations (2) and (2') above, f, g, h, i, j, and k are integers between 0 and 10, inclusive. Preferably, they are integers of 1 or greater, more preferably 8 or less, more preferably 4 or less, and even more preferably 2 or less. f+g+h+i+j+k represents the equivalent amount of the linking chain R included in formula (2) and formula (2') above. A value of 1 or more is preferable from the viewpoint of suppressing steric repulsion between groups having C=O bonds (e.g., (meth)acryloyl groups) located at the terminal end of the molecule and preventing the elimination of C=O bonded groups (e.g., (meth)acryloyl groups). A value of 2 or more is more preferable, and a value of 4 or more is particularly preferable. On the other hand, a value of 20 or less is preferable from the viewpoint of the mechanical strength of the protective layer. A value of 18 or less is more preferable, a value of 12 or less is even more preferable, and a value of 6 or less is particularly preferable.

[0058] In formulas (2) and (2') above, R is independently selected from the viewpoint of suppressing steric repulsion between groups having C=O bonds located at the terminal end of the molecule (e.g., (meth)acryloyl groups) and preventing the elimination of C=O bonded groups (e.g., (meth)acryloyl groups), to be an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) is preferred to be a divalent group. Among these, an oxyalkylene group having 1 to 8 carbon atoms is preferred from the viewpoint of ease of synthesis. Examples of oxyalkylene groups having 1 to 8 carbon atoms include -O-CH2-, -O-CH2-CH2-, -O-CH(CH3)-CH2-, -O-CH2-CH(CH3)-, -O-CH2-CH2-CH2-, and -O-CH2-CH2-CH2-CH2-. Among these, -O-CH2-CH2- and -O-CH(CH3)-CH2- are preferred, and -O-CH2-CH2- is more preferred. When the linking chain R is an oxyalkylene group having 1 to 8 carbon atoms, the number of oxyalkylene groups in one molecule of compound b having the structure represented by formula (2') is preferably 2 or more, more preferably 4 or more. On the other hand, it is preferably 12 or less, more preferably 10 or less, and more preferably 6 or less.

[0059] In equation (2) above, T represents a bond with any atom. Examples of such atoms include carbon, hydrogen, nitrogen, and oxygen.

[0060] In formula (2) above, Q is preferably a hydroxyl group or the following formula (3) from the viewpoint of having polarity and suppressing the formation of a mixed layer. Furthermore, Q in formula (2') above is preferably a hydroxyl group or the following formula (3') from the viewpoint of having polarity and suppressing the formation of a mixed layer.

[0061] In equations (2) and (2') above, Z 1 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and preferably at least one of them is an alkyl group having 1 to 4 carbon atoms. In formulas (2) and (2') above, Z 1 It is more preferable that two or more of them are alkyl groups having 1 to 4 carbon atoms, and even more preferable that four or more of them are alkyl groups having 1 to 4 carbon atoms, and all Z 1 It is particularly preferable that the alkyl group has 1 to 4 carbon atoms. 1 If the alkyl group has 1 to 4 carbon atoms, then acidic gases such as ozone will react to Z 1 Because it sterically inhibits the approach of the unreacted carbon-carbon double bond to which it is bonded, it has good gas resistance. Also, Z in equations (2) and (2') 1 When is an alkyl group having 1 to 4 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, i.e., a methyl group.

[0062] [Formula (3)] TIFF0007896636000013.tif33170

[0063] In formula (3), Z 1 Z represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 2 represents a bond with R in formula (1) or formula (2). T represents a bond with any atom. Z in equation (3) 1 When is an alkyl group having 1 to 4 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, i.e., a methyl group.

[0064] [Formula (3')] TIFF0007896636000014.tif29170

[0065] In formula (3'), Z 1 Z represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 2 represents the bond with R in equation (1') or equation (2'). Z in equation (3') 1 When is an alkyl group having 1 to 4 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, i.e., a methyl group.

[0066] Furthermore, it is preferable that the protective layer of this electrophotographic photoreceptor is a layer containing a polymer having a group represented by R' below, a structure represented by formula (5) below, and a structure represented by formula (6) below.

[0067] R': Alkylene group with 1 to 8 carbon atoms, oxyalkylene group with 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - A divalent group selected from (where p is between 2 and 6)

[0068] [Formula (5)] JPEG0007896636000015.jpg32158

[0069] In formula (5), Z 3 This represents a bond with any atom.

[0070] [Formula (6)] JPEG0007896636000016.jpg34166

[0071] In formula (6), Z 4 represents an alkyl group with 1 to 4 carbon atoms. T represents a bond with any atom.

[0072] [R'] The group represented by R' is an alkylene group having 1 to 8 carbon atoms, an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p - (where p is between 2 and 6) is a divalent group selected from these. These preferred embodiments are the same as the linked chain R in formulas (1), (2), (1'), or (2') described above.

[0073] [Equations (5) and (6)] In the above equation (5), Z 3 The symbol represents a bond with any atom. Examples of such atoms include carbon, hydrogen, nitrogen, and oxygen. In the above equation (6), Z 4 represents an alkyl group having 1 to 4 carbon atoms. T represents a bond with any atom. Examples of such atoms include carbon, hydrogen, nitrogen, and oxygen. Z in equation (6) 4When is an alkyl group having 1 to 4 carbon atoms, the number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, i.e., a methyl group.

[0074] Furthermore, it can be confirmed, for example, by the following method, that the protective layer of the electrophotographic photoreceptor is a layer containing a polymer having the group represented by R', the structure represented by formula (5), and the structure represented by formula (6). By isolating the protective layer from the electrophotographic photoreceptor and performing thermal decomposition GC / MS analysis, the structure contained in the protective layer can be analyzed, and the group represented by R', the structure represented by formula (5), and the structure represented by formula (6) can be detected. When the compound has the structure represented by formula (5), examples of compounds that can be detected by pyrolysis GC / MS analysis include pentaerythritol, methylpentaerythritol, dimethylpentaerythritol, trimethylpentaerythritol, tetramethylpentaerythritol, ethylpentaerythritol, diethylpentaerythritol, triethylpentaerythritol, tetraethylpentaerythritol, and dipentaerythritol. In the case of having the structure represented by formula (6), examples of compounds contained in the protective layer before curing (before polymerization) include acrylic acid, methacrylic acid, 2-ethylpropa-2-enoic acid, 2-propylpropa-2-enoic acid, 2-butylpropa-2-enoic acid, methyl acrylate, methyl methacrylate, 2-ethylpropa-2-enoic acid, 2-propylpropa-2-enoic acid, 2-butylpropa-2-enoic acid, ethyl acrylate, ethyl methacrylate, 2-ethylpropa-2-enoic acid, 2-propylpropa-2-enoic acid, 2-butylpropa-2-enoic acid, and the like. Compounds contained in these pre-curing (pre-polymerization) protective layers may remain in the cured protective layer as unreacted compounds. In such cases, if thermal decomposition GC / MS analysis is performed on the cured protective layer, the unreacted compounds may be detected, and it can be inferred that the protective layer contains a polymer having the structure represented by formula (6).

[0075] [Molecular weight] The molecular weights of compound a having the structure represented by formula (1') and compound b having the structure represented by formula (2') are preferably 400 to 1400. As mentioned above, compounds a and b do not have low-polarity side chains such as alkyl groups, and have a structure in which a group with a relatively high polarity C=O bond (e.g., acryloyl group, methacryloyl group) or a hydroxyl group is located on the outside of the molecule. Therefore, even if the molecular weight is small, it is thought that they are unlikely to form a mixed layer. However, if the molecular weight is too small, the effect of suppressing mixing may become relatively small. On the other hand, if the molecular weights of compounds a and b are large, it is generally thought that they are unlikely to form a mixed layer. From this viewpoint, the molecular weights of compounds a and b are preferably 400 or more, more preferably 500 or more, and particularly preferably 550 or more. On the other hand, they are preferably 1400 or less, more preferably 1200 or less, and particularly preferably 1000 or less.

[0076] [Functional group equivalent] With respect to compound a represented by formula (1') or compound b represented by formula (2'), it is preferable that the molecular weight X of compound a or compound b and the number Y of acryloyl groups and methacryloyl groups contained in one molecule satisfy the following formula (4). 120 ≤ X / Y ≤ 400 (4) If there are a large number of polar (meth)acryloyl groups or hydroxyl groups, the mixing-inhibiting effect of the polar groups mentioned above will be enhanced, and the formation of a mixed layer can be further suppressed. In other words, by having a sufficient number of polar groups (acryloyl groups or methacryloyl groups) relative to the molecular weight, the formation of a mixed layer can be further suppressed. In addition, sufficient mechanical strength to exhibit wear resistance can be obtained. From this viewpoint, in compound a or b represented by either formula (1') or (2'), the ratio of the molecular weight X of compound a or b to the number Y of acryloyl groups and methacryloyl groups contained in one molecule (X / Y), i.e., the functional group equivalent, is preferably 400 or less, and more preferably 300 or less, 200 or less, and 180 or less. On the other hand, if the ratio (X / Y), i.e., the functional group equivalent, is large, it is considered that residual stress will be low and cracks will not easily occur. Therefore, it is preferable that the ratio (X / Y), i.e., the functional group equivalent, be 120 or more, and more preferably 130 or more, 140 or more, and 150 or more. The number Y of acryloyl groups and methacryloyl groups in one molecule is preferably 2 or more, more preferably 3 or more, and more preferably 4 or more. On the other hand, it is preferably 12 or less, more preferably 10 or less, even more preferably 8 or less, and particularly preferably 6 or less.

[0077] (metal oxide particles) This protective layer preferably contains metal oxide particles from the viewpoint of imparting charge transport ability and improving mechanical strength.

[0078] As the metal oxide particles, metal oxide particles that can be used in electrophotographic photoreceptors can be used. Examples of metal oxide particles include metal oxide particles containing one metal element such as titanium oxide, tin 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 metal oxide particles may be of a single type or a mixture of multiple types. Among these metal oxide particles, titanium oxide, tin oxide, aluminum oxide, silicon oxide, or zinc oxide are preferred, and titanium oxide and tin oxide are more preferred. Titanium oxide is particularly preferred.

[0079] Any of the following crystalline forms of titanium dioxide particles can be used: rutile, anatase, brookite, or amorphous. Furthermore, a mixture of these particles in different crystalline states may be included.

[0080] The surface of the metal oxide particles may be subjected to various surface treatments. For example, they may be treated with inorganic substances such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, and silicon oxide, or with organic substances such as stearic acid, polyols, and organosilicon compounds. In particular, when titanium oxide particles are used, surface treatment with organosilicon compounds is preferred. Examples of the organosilicon compounds include silicone oils such as dimethylpolysiloxane, organosilanes such as methyldimethoxysilane, silazanes such as hexamethyldisilazane, and silane coupling agents such as 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. In particular, from the viewpoint of improving the mechanical strength of the protective layer, 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane, which have chain polymerizable functional groups, are preferred. Furthermore, the outermost surface of these surface-treated particles may have been treated with a treatment agent such as aluminum oxide, silicon oxide, or zirconium oxide before being treated with such a treatment agent.

[0081] The particle size of the metal oxide particles is preferably such that the average primary particle diameter is 500 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. Furthermore, it is more preferably 1 nm or more, and even more preferably 5 nm or more. This average primary particle diameter can be determined by the arithmetic mean of the particle diameters directly observed using a transmission electron microscope (TEM).

[0082] Furthermore, from the viewpoint of electrical properties, the content of metal oxide particles in the protective layer is preferably 20 parts by mass or more per 100 parts by mass of the polymer contained in the protective layer, more preferably 60 parts by mass or more, and more preferably 80 parts by mass or more. On the other hand, from the viewpoint of maintaining surface charge, it is preferably 200 parts by mass or less, more preferably 160 parts by mass or less, and more preferably 120 parts by mass or less.

[0083] (Other materials) In addition to the materials described above, this protective layer may contain other materials as needed. These other materials may include, for example, a "charge transport substance" to enhance charge transport ability, or a "polymerization initiator" to promote polymerization. Furthermore, it may also contain, as needed, stabilizers (heat stabilizers, UV absorbers, light stabilizers, antioxidants, etc.), dispersants, antistatic agents, colorants, lubricants, etc. These can be used individually or in any ratio and combination of two or more as appropriate.

[0084] [Charge transport material] The charge transport material contained in this protective layer can be the same as the charge transport material used in the photosensitive layer described later.

[0085] Furthermore, from the viewpoint of improving the Martens hardness of the photoreceptor surface, the protective layer may contain a structure formed by polymerizing a charge transport material having chain polymerizable functional groups. Examples of chain polymerizable functional groups in charge transport materials are acryloyl groups, methacryloyl groups, vinyl groups, epoxy groups, etc. Among these, acryloyl groups or methacryloyl groups are preferred from the viewpoint of curability. The structure of the charge transport material portion of the charge transport material having chain polymerizable functional groups is preferably a carbazole derivative, arylamine derivative, stilbene derivative, butadiene derivative or enamine derivative, or a compound in which multiple types of these compounds are bonded together.

[0086] The amount of charge transport material in the protective layer of this electrophotographic photoreceptor is not particularly limited. From the viewpoint of electrical properties, it is preferable that the amount is 10 parts by mass or more per 100 parts by mass of a polymer having the structure represented by formula (1) or (2), or a polymer of a compound having the structure represented by formula (1') or (2'), or a polymer having the group represented by R', the structure represented by formula (5), and the structure represented by formula (6), more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more. Furthermore, from the viewpoint of maintaining good surface resistance, it is more preferable that the amount is 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less.

[0087] [Polymerization initiator] Polymerization initiators include thermal polymerization initiators, photopolymerization initiators, and the like.

[0088] Examples of thermal polymerization initiators include peroxide compounds such as 2,5-dimethylhexane-2,5-dihydroperoxide and azo compounds such as 2,2'-azobis(isobutyronitrile).

[0089] Photopolymerization initiators can be classified into direct cleavage type and hydrogen abstraction type based on differences in their radical generation mechanisms.

[0090] 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, benzyldimethylketal, 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-tosylbenzoin; and acylphosphine oxide-based compounds such as diphenyl(2,4,6-trimethylbenzoyl)phosphone oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphone oxide, and lithiumphenyl(2,4,6-trimethylbenzoyl)phosphonate.

[0091] Examples of hydrogen abstraction type photopolymerization initiators include benzophenone compounds such as benzophenone, 4-benzoylbenzoic acid, 2-benzoylbenzoic acid, methyl 2-benzoylbenzoate, methyl benzoylformate, benzyl, p-anisyl, 2-benzoylnaphthalene, 4,4'-bis(dimethylamino)benzophenone, 4,4'-dichlorobenzophenone, and 1,4-dibenzoylbenzene; anthraquinone or thioxanthone compounds such as 2-ethylanthraquinone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone. Other photopolymerization initiators include camphorquinone, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, acridine compounds, triazine compounds, and imidazole compounds.

[0092] In order to efficiently absorb light energy and generate radicals, it is preferable that the photopolymerization initiator has an absorption wavelength within the wavelength range of the light source used for irradiation. From the viewpoint of preventing a decrease in radical generation efficiency, it is preferable to include an acyl phosphine oxide compound that has an absorption wavelength on the relatively long wavelength side among photopolymerization initiators. In this case, from the viewpoint of compensating for the curability of the protective layer surface, it is even more preferable to use an acylphosphine oxide compound and a hydrogen abstraction type initiator in combination. The ratio of the hydrogen abstraction type initiator to the acylphosphine oxide compound is not particularly limited. For example, from the viewpoint of compensating for surface curability, it is preferable to contain 0.1 parts by mass or more of the hydrogen abstraction type initiator per 1 part by mass of the acylphosphine oxide compound, and from the viewpoint of maintaining internal curability, it is preferable to contain it in a ratio of 5 parts by mass or less.

[0093] Furthermore, substances that have a photopolymerization-promoting effect can be used alone or in combination with the above-mentioned photopolymerization initiator. Examples of substances that have a photopolymerization-promoting effect include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino)ethyl benzoate, and 4,4'-dimethylaminobenzophenone.

[0094] The polymerization initiator may be used as a mixture of one or more types. The content of the polymerization initiator is preferably 0.5 to 40 parts by mass per 100 parts by mass of the total radical polymerizable content, and more preferably 1 part by mass or more, or 20 parts by mass or less.

[0095] (Method for forming this protective layer) Next, the method for forming this protective layer will be explained. The method for forming this protective layer is not particularly limited. For example, the protective layer can be formed by applying a coating solution (referred to as the "coating solution for forming this protective layer") in which compound a having the structure represented by formula (1') or compound b having the structure represented by formula (2'), optionally the metal oxide particles, optionally the polymerization initiator, optionally the charge transporter, and optionally other substances are dispersed in a solvent or dispersion medium, onto the photosensitive layer and curing it.

[0096] [Solvent used in coating solutions for forming protective layers] Examples of organic solvents used in the coating solution for forming the protective layer include alcohols such as methanol, ethanol, propanol, and 2-methoxyethanol; ethers such as tetrahydrofuran; esters such as methyl formate; ketones such as acetone; aromatic hydrocarbons such as benzene and toluene; chlorinated hydrocarbons such as dichloromethane and chloroform; nitrogen-containing compounds such as n-butylamine; and aprotic polar solvents such as acetonitrile. Any combination and proportion of these mixed solvents can also be used. Furthermore, even organic solvents that do not dissolve the protective layer material of the electrophotographic photoreceptor on their own can be used if they become soluble when mixed with, for example, the above organic solvents. Generally, using a mixed solvent can reduce uneven coating. When using the immersion coating method described later, it is preferable to select a solvent that does not dissolve the lower layer. From this viewpoint, it is preferable to include alcohols that have low solubility in polycarbonate and polyarylate, which are suitably used for the photosensitive layer.

[0097] The ratio of organic solvent to solid content used in this protective layer-forming coating solution varies depending on the application method of the protective layer-forming coating solution. It should be adjusted as appropriate to ensure that a uniform coating film is formed using the applicable application method.

[0098] [Application Method] The method for applying the coating solution to form this protective layer is not particularly limited, and examples include spray coating, spiral coating, ring coating, and immersion coating.

[0099] After forming the coating film using the above coating method, the coating film is dried. At this time, the temperature and time of drying are not specified as long as the necessary and sufficient drying is achieved. However, if the protective layer is applied by air drying only after the photosensitive layer has been applied, it is preferable to perform sufficient drying using the method described later for forming the photosensitive layer.

[0100] [Curing method for this protective layer] This protective layer can be formed by applying the protective layer-forming coating solution and then curing it by applying external energy. Examples of external energy that can be used include heat, light, and radiation. Due to these curing reactions, compound a, represented by formula (1'), polymerizes to polymer A or A', and compound b, represented by formula (2'), polymerizes to polymer B or B'.

[0101] Methods for applying thermal energy include heating using gases such as air and nitrogen, steam, various heat transfer fluids, infrared radiation, and electromagnetic waves. Furthermore, this heating can be performed from either the coated surface side or the support side. The heating temperature is preferably between 100°C and 170°C.

[0102] For light energy, UV irradiation light sources such as high-pressure mercury lamps, metal halide lamps, electrodeless lamp bulbs, and light-emitting diodes, which emit light at wavelengths primarily in the ultraviolet (UV) range, can be used. Furthermore, it is possible to select a visible light source that matches the absorption wavelength of the chain-polymerizable compound or photopolymerization initiator. The light irradiation dose is 10 J / cm² from the perspective of curing properties. 2 The above is preferable, 30 J / cm 2 The above is even more preferable, 100 J / cm² 2 The above is particularly preferable. Also, from the viewpoint of electrical characteristics, 500 J / cm 2 The following is preferable: 300 J / cm² 2 The following is even more preferable: 200 J / cm² 2 The following are particularly preferable. On the other hand, one example of radiation energy is that which uses electron beams (EB).

[0103] Among these energy sources, light energy is preferred from the viewpoint of ease of reaction rate control, simplicity of the apparatus, and long pod life.

[0104] After curing the protective layer, a heating step may be added from the viewpoint of relieving residual stress, relieving residual 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.

[0105] (layer thickness) From the viewpoint of abrasion resistance, the thickness of this protective layer is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, from the viewpoint of electrical properties, it is preferably 5 μm or less, and more preferably 3 μm or less. Furthermore, from a similar viewpoint, the thickness of the protective layer is preferably 1 / 50 or more of the thickness of the photosensitive layer, more preferably 1 / 40 or more, and even more preferably 1 / 30 or more. On the other hand, it is preferably 1 / 5 or less, more preferably 1 / 10 or less, and even more preferably 1 / 20 or less.

[0106] <Main photosensitive layer> The photosensitive layer in this electrophotographic photoreceptor (also referred to as "this photosensitive layer") only needs to be a layer containing at least a charge generating material (CGM) and a charge transporting material.

[0107] This photosensitive layer may be a single-layer photosensitive layer containing both a charge-generating material and a charge-transporting material within the same layer, or it may be a multilayer photosensitive layer separated into a charge-generating layer and a charge-transporting layer. Whether it is a single-layer or multilayer photosensitive layer, the mechanism by which a mixed layer is formed between the protective layer and the photosensitive layer is the same: the concentration of charge transport material in the mixed layer is lower than that of the photosensitive layer, resulting in a decrease in charge transport capability. Therefore, the effects of the present invention can be enjoyed with either a single-layer or multilayer photosensitive layer. However, generally, in a single-layer photosensitive layer, in addition to the binder resin, hole transport material, electron transport material, and charge generating material are contained in the same layer, resulting in a higher proportion of low-molecular-weight components and a lower glass transition temperature of the photosensitive layer compared to a multilayer photosensitive layer. Therefore, the photosensitive layer is more prone to softening due to heating and drying when forming the protective layer and the heat generated during curing, making it easier to form a mixed layer in a single-layer photosensitive layer. From this perspective, it is considered that a single-layer photosensitive layer can enjoy the effects of the present invention even more than a multilayer photosensitive layer.

[0108] <Single-layer photosensitive layer> If the photosensitive layer is a single-layer photosensitive layer, it is preferable that at least a charge generating material (CGM), a hole transport material (HTM), an electron transport material (ETM), and a binder resin are contained within the same layer.

[0109] (Charge-generating material) Various photoconductive materials, such as inorganic photoconductive materials and organic pigments, can be used as charge-generating materials for this photosensitive layer. Among these, organic pigments are particularly preferred, and phthalocyanine pigments and azo pigments are even more preferred.

[0110] In particular, when phthalocyanine pigments are used as charge-generating materials, specific examples include metal-free phthalocyanines, phthalocyanines coordinated with metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, and germanium, or their oxides and halides. Examples of ligands for metal atoms with a valency of 3 or higher include oxygen atoms, chlorine atoms, as well as hydroxyl groups and alkoxy groups. Among these, X-type and τ-type metal-free phthalocyanines, A-type, B-type, and D-type titanyl phthalocyanines, vanadyl phthalocyanines, chloroindium phthalocyanines, chlorogallium phthalocyanines, and hydroxygallium phthalocyanines, which have particularly high sensitivity, are preferred.

[0111] Furthermore, when using azo pigments, various known bis-azo pigments and tris-azo pigments are preferably used.

[0112] Furthermore, the charge-generating material may be used alone, or two or more may be used in any combination and ratio. In addition, when two or more charge-generating materials are used in combination, the charge-generating materials may be mixed afterwards, or they may be mixed during the manufacturing or processing steps of the charge-generating materials, such as synthesis, pigmentation, or crystallization.

[0113] From the viewpoint of electrical properties, it is desirable that the particle size of the charge-generating material be small. Specifically, the particle size of the charge-generating material is preferably 1 μm or less, and more preferably 0.5 μm or less. The lower limit is 0.01 μm or more. Here, the particle size of the charge-generating material refers to the particle size when it is contained in the photosensitive layer.

[0114] Furthermore, from the viewpoint of sensitivity, the amount of charge-generating material in the single-layer photosensitive layer is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Also, from the viewpoint of sensitivity and chargeability, it is preferably 50% by mass or less, and more preferably 20% by mass or less.

[0115] (charge transport material) Charge transport materials are classified into hole transport materials, which primarily possess hole transport ability, and electron transport materials, which primarily possess electron transport ability. However, if the photosensitive layer is a single-layer photosensitive layer, it is preferable to contain at least a hole transport material and an electron transport material within the same layer.

[0116] [Hole transport material] The hole transport material (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, arylamine derivatives, stilbene derivatives, butadiene derivatives, and enamine derivatives, as well as compounds formed by the combination of multiple types of these compounds, and electron-donating materials such as polymers having groups made of these compounds in their main chain or side chain.

[0117] Among these, carbazole derivatives, arylamine derivatives, stilbene derivatives, butadiene derivatives, and enamine derivatives, as well as compounds formed by combining multiple types of these compounds, are preferred, with arylamine derivatives and enamine derivatives being more preferred.

[0118] The molecular weight of the hole transporter is preferably 600 or higher, more preferably 650 or higher, even more preferably 700 or higher, and particularly preferably 740 or higher, from the viewpoint of electrical properties. On the other hand, from the viewpoint of ease of synthesis and stability of the compound, it is preferably 1200 or lower, more preferably 1000 or lower, and even more preferably 900 or lower.

[0119] The hole transport material may be used alone, or two or more may be used in any ratio and combination.

[0120] The following are examples of preferred hole transporter structures.

[0121] TIFF0007896636000017.tif64170

[0122] TIFF0007896636000018.tif74170

[0123] TIFF0007896636000019.tif98170

[0124] Among the hole transport materials listed above, HTM31, HTM32, HTM33, HTM34, HTM35, HTM39, HTM40, HTM41, HTM42, HTM43, and HTM48 are preferred from the viewpoint of electrical properties, and HTM39, HTM40, HTM41, HTM42, HTM43, and HTM48 are even more preferred.

[0125] [Electron transport material] The electron transport material (ETM) can be selected from known materials. Examples include electron-withdrawing substances such as aromatic nitro compounds like 2,4,7-trinitrofluorenone, cyano compounds like tetracyanoquinodimethane, and quinone compounds like diphenoquinone, as well as known cyclic ketone compounds and perylene pigments (perylene derivatives). Among these, quinone compounds and perylene pigments (perylene derivatives) are preferred from the viewpoint of electrical properties, and quinone compounds are more preferred. Among the quinone compounds mentioned above, diphenoquinone or dinaphthylquinone is preferred from the viewpoint of electrical properties. Of these, dinaphthylquinone is more preferred.

[0126] The molecular weight of the electron transport material is preferably 400 or more, more preferably 410 or more, and even more preferably 420 or more, from the viewpoint of electrical properties. On the other hand, it is preferably 1000 or less, more preferably 800 or less, and even more preferably 600 or less.

[0127] The electron transport material may be used alone, or two or more may be used in any ratio and combination.

[0128] The following are examples of preferred electron transport material structures.

[0129] TIFF0007896636000020.tif39170

[0130] Among the electron transport materials mentioned above, ET-2 and ET-5 are preferred in terms of electrical properties, with ET-2 being even more preferred.

[0131] [Content of hole transporter and electron transporter] The ratio of the mass of electron transport material to the mass of hole transport material in a single-layer photosensitive layer is preferably 0.3 or higher from the viewpoint of electron transport properties, and more preferably 0.4 or higher from the viewpoint of electrical properties. On the other hand, from the viewpoint of hole transport properties, it is preferably 1.0 or lower, more preferably 0.9 or lower from the viewpoint of suppressing the deposition of electron transport material, and more preferably 0.8 or lower from the viewpoint of adhesion.

[0132] From the viewpoint of hole transportability, the content of the hole transport substance in this electrophotographic photoreceptor is preferably 50 parts by mass or more per 100 parts by mass of the binder resin described below, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more. On the other hand, regarding the upper limit, from the viewpoint of suppressing precipitation, it is more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less.

[0133] (Binder resin) Next, we will explain the binder resin used in this photosensitive layer. Examples of binder resins used in this photosensitive layer include vinyl polymers or copolymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride; 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 partially crosslinked cured products thereof. The above resins may also be modified with silicon reagents, etc. These can be used individually, or two or more can be used in any ratio and combination.

[0134] Furthermore, the binder resin used in this photosensitive layer preferably contains one or more polymers obtained by interfacial polymerization.

[0135] The binder resin obtained by the above interfacial polymerization is preferably a polycarbonate resin or a polyester resin, more preferably a polycarbonate resin or a polyarylate resin, and even more preferably a polycarbonate resin. In particular, it is preferable that the polymer is derived from an aromatic diol.

[0136] (Other substances) In addition to the materials mentioned above, the photosensitive layer may contain additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents to improve film-forming properties, flexibility, coatability, stain resistance, gas resistance, and light resistance. The photosensitive layer may also contain various additives such as sensitizers, dyes, pigments (excluding those that are charge-generating substances, hole-transporting substances, or electron-transporting substances), and surfactants as needed. Examples of surfactants include silicone oil and fluorine-based compounds. In the present invention, these can be used individually or in any ratio and combination of two or more as appropriate.

[0137] Furthermore, in order to reduce the frictional resistance of the photosensitive layer surface, the photosensitive layer may contain fluororesins, silicone resins, etc., and may also contain particles made of these resins or particles of inorganic compounds such as aluminum oxide.

[0138] (layer thickness) When the photosensitive layer is a single-layer photosensitive layer, the thickness of the photosensitive layer is preferably 20 μm or more, and more preferably 25 μm or more, from the viewpoint of dielectric breakdown resistance. On the other hand, from the viewpoint of electrical characteristics, it is preferably 50 μm or less, and more preferably 40 μm or less.

[0139] <Laminated photosensitive layer> When the electrophotographic photoreceptor is a multilayer type, for example, a configuration can be given in which a charge transport layer (CTL) containing an electron transport material (ETM) and a hole transport material (HTM) is laminated on a charge generating layer (CGL) containing a charge generating material (CGM). In this case, it is also possible to include other layers besides the charge generating layer (CGL) and the charge transport layer (CTL).

[0140] <Charge Generation Layer (CGL)> The charge generation layer typically contains a charge-generating material (CGM) and a binder resin. The charge-generating material (CGM) and binder resin are the same as those described for the single-layer photosensitive layer.

[0141] (Other ingredients) The charge generating layer may contain other components in addition to the charge generating substance and binder resin, as needed. For example, known additives such as antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, visible light shielding agents, and fillers may be included to improve film-forming properties, flexibility, coatability, stain resistance, gas resistance, light resistance, etc.

[0142] (composition ratio) In the charge generation layer, if the proportion of charge generation material is too high, the stability of the coating solution may decrease due to aggregation of the charge generation material, etc. On the other hand, if the proportion of charge generation material is too low, it may lead to a decrease in the sensitivity of the photoreceptor. Therefore, the mixing ratio (mass) of binder resin and charge generation material is preferably such that the charge generation material is contained in 10 parts by mass or more per 100 parts by mass of binder resin, more preferably 30 parts by mass or more, on the other hand, it is preferable to contain it in a proportion of 1000 parts by mass or less, and even more preferably 500 parts by mass or less. From the viewpoint of film strength, it is more preferable to contain it in a proportion of 300 parts by mass or less, and even more preferably 200 parts by mass or less.

[0143] (layer thickness) The thickness of the charge generation layer is preferably 0.1 μm or more, and more preferably 0.15 μm or more. On the other hand, it is preferably 10 μm or less, and more preferably 6 μm or less.

[0144] <Charge transport layer (CTL)> The charge transport layer (CTL) typically contains a hole transport material (HTM) and a binder resin, and may also contain an electron transport material (ETM). The electron transport material (ETM), hole transport material (HTM), and binder resin are the same as those described for the single-layer photosensitive layer.

[0145] In the charge transport layer (CTL), the blending ratio of the binder resin to the hole transport material (HTM) is preferably 20 parts by mass or more of the hole transport material (HTM) per 100 parts by mass of the binder resin, more preferably 30 parts by mass or more from the viewpoint of reducing residual potential, and even more preferably 40 parts by mass or more from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is preferable to blend the hole transport material (HTM) at a ratio of 200 parts by mass or less per 100 parts by mass of the binder resin, more preferably 150 parts by mass or less from the viewpoint of compatibility between the hole transport material (HTM) and the binder resin, and particularly preferable 120 parts by mass or less from the viewpoint of glass transition temperature.

[0146] (Other ingredients) The charge transport layer may contain other components as needed, in addition to electron transport material (ETM), hole transport material (HTM), and binder resin. For example, known additives such as antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, visible light shielding agents, and fillers may be included to improve film formation, flexibility, coatability, stain resistance, gas resistance, light resistance, etc.

[0147] (layer thickness) The thickness of the charge transport layer is not particularly limited. From the viewpoint of electrical properties, image stability, and high resolution, it is preferably 5 μm to 50 μm, more preferably 10 μm to 35 μm, and even more preferably 15 μm to 25 μm.

[0148] <Method for forming a photosensitive layer> In both the laminated and single-layer types, each of the above layers can be formed as follows. The coating solution obtained by dissolving or dispersing the substance to be contained in a solvent can be formed on a conductive support by sequentially repeating the coating and drying process for each layer using known methods such as immersion coating, spray coating, nozzle coating, bar coating, roll coating, and blade coating. However, this method of formation is not limited to this specific method.

[0149] There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution. Specific examples include alcohols such as methanol, ethanol, propanol, and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane, and dimethoxyethane; aromatic hydrocarbons such as benzene, toluene, and xylene; and chlorinated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, and trichloroethylene. These may be used individually or in any combination and of any type.

[0150] The amount of solvent or dispersion medium used is not particularly limited. It is preferable to appropriately adjust the physical properties of the coating solution, such as the solid content concentration and viscosity, to be within the desired range, taking into consideration the purpose of each layer and the properties of the selected solvent / dispersion medium. For drying the coated film, it is preferable to dry it by touch at room temperature, and then heat-dry it at a temperature range of 30°C to 200°C for 1 minute to 2 hours, either stationary or under a fan. The heating temperature may be constant, or it may be changed during the drying process.

[0151] <This conductive support> The conductive support for this electrophotographic photoreceptor (also referred to as "this conductive support") is not particularly limited as long as it supports the layer formed thereon and exhibits conductivity. As the conductive support, for example, metal materials such as aluminum, aluminum alloys, stainless steel, copper, and nickel, or resin materials that have been imparted conductivity by coexisting conductive powders such as metal, carbon, and tin oxide, or resins, glass, paper, etc., on which conductive materials such as aluminum, nickel, and ITO (indium tin oxide alloy) have been deposited or coated on their surface can be mainly used. The conductive support can take the form of a drum, cylinder, sheet, belt, or other similar shape. This conductive support may be a conductive support made of a metal material to which a conductive material with an appropriate resistance value is coated for the purpose of controlling conductivity and surface properties or covering defects.

[0152] When using a metal material such as an aluminum alloy as the conductive support, the metal material may be coated with an anodic oxide film before use.

[0153] The average thickness of the anodic oxide coating is preferably 20 μm or less, and more preferably 7 μm or less.

[0154] When applying an anodized coating to a metal material, it is preferable to perform a sealing treatment. The sealing treatment can be carried out by known methods.

[0155] The surface of this conductive support may be smooth, or it may be roughened by using a special cutting method or by polishing. Alternatively, it may be roughened by mixing particles of an appropriate particle size into the material constituting the support. Furthermore, an undercoat layer, as described below, may be provided between the conductive support and the photosensitive layer to improve adhesion, blocking properties, etc.

[0156] <Main underlay layer> This electrophotographic photoreceptor may have an undercoat layer (also referred to as "this undercoat layer") between the photosensitive layer and the conductive support.

[0157] For this undercoat, for example, a resin, or a resin in which particles such as organic pigments or metal oxides are dispersed, can be used. Examples of organic pigments used in the undercoat include phthalocyanine pigments, azo pigments, and perylene pigments. In particular, phthalocyanine pigments and azo pigments used as charge-generating materials, as mentioned above, are noteworthy.

[0158] Examples of metal oxide particles used in this undercoat 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 may use only one type of particle, or it may be a mixture of multiple types of particles in any ratio and combination.

[0159] Among the metal oxide particles mentioned above, titanium oxide and aluminum oxide are preferred, with titanium oxide being particularly preferred. The titanium oxide particles may have their surfaces treated with any inorganic or organic substance, for example. Furthermore, any of the following crystalline forms of titanium oxide particles can be used: rutile, anatase, brookite, or amorphous. Multiple crystalline states may also be included.

[0160] The particle size of the metal oxide particles used in this undercoat is not particularly limited. From the standpoint of the properties of the undercoat and the stability of the solution for forming the undercoat, the average primary particle size is preferably 10 nm or more, and more preferably 100 nm or less, and more preferably 50 nm or less.

[0161] The binder resin used in this undercoat can be selected from, for example, polyvinyl acetal resins such as polyvinyl butyral resin, polyvinyl formal resin, and partially acetalized polyvinyl butyral resin in which a portion of the butyral is modified with formal or acetal; and insulating resins such as polyarylate resin, polycarbonate resin, polyester resin, phenoxy resin, acrylic resin, methacrylic resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, styrene-alkyd resin, silicone-alkyd resin, and phenol-formaldehyde resin. However, it is not limited to these polymers. Furthermore, these binder resins may be used individually, mixed in combination of two or more types, or used in a cured form together with a curing agent. Among these, polyvinyl acetal resins, alcohol-soluble copolymerized polyamides, and modified polyamides are preferred because they exhibit good dispersibility and coating properties. Of these, alcohol-soluble copolymerized polyamides are particularly preferred.

[0162] The mixing ratio of particles to the binder resin can be arbitrarily selected. Using a ratio in the range of 10% to 500% by mass is preferable in terms of dispersion stability and coatability.

[0163] The thickness of this undercoat layer can be arbitrarily selected. Based on the characteristics of the electrophotographic photoreceptor and the coatability of the dispersion, it is preferably 0.1 μm or more, and more preferably 20 μm or less. The undercoat layer may also contain known antioxidants, etc.

[0164] <Other layers> Furthermore, in addition to the conductive support, photosensitive layer, protective layer, and undercoat layer described above, the electrophotographic photoreceptor may have other layers as needed.

[0165] <Physical properties of this electrophotographic photoreceptor> This electrophotographic photoreceptor can have the following physical properties.

[0166] (Martens hardness) In this electrophotographic photoreceptor, from the perspective of providing sufficient wear resistance for practical use, its Martens hardness is 230 N / mm². 2 Preferably, the load is 250 N / mm² or higher, and more preferably 250 N / mm². 2 Among them, 290 N / mm 2 It is more preferable that the above conditions are met. In this invention, the Martens hardness of the photoreceptor refers to the Martens hardness measured from the surface side of the photoreceptor. The Martens hardness can be measured by the method described in the examples below.

[0167] (elastic deformation rate) Furthermore, from the viewpoint of providing sufficient wear resistance for practical purposes, the elastic deformation rate of this electrophotographic photoreceptor is preferably 25% or more, more preferably 30% or more, and even more preferably 32% or more. In this invention, the elastic deformation rate of the photoreceptor refers to the elastic deformation rate measured from the surface side of the photoreceptor. The aforementioned elastic deformation rate can be measured by the method described in the embodiments below.

[0168] (Presence or absence of a mixed layer) As described above, when forming the protective layer, for example, when applying the protective layer forming coating solution to the surface of the photosensitive layer and heating and drying it, or when curing it afterward, this electrophotographic photoreceptor can suppress the formation of a mixed layer (a layer in which the components of both layers are mixed) between the protective layer and the photosensitive layer. Therefore, this electrophotographic photoreceptor can be configured without having a mixed layer between the protective layer and the photosensitive layer. However, the absence of a mixed layer in this electrophotographic photoreceptor is not a necessary condition, because the effects of the present invention can be enjoyed without confirming the presence or absence of a mixed layer.

[0169] Furthermore, whether or not a mixed layer is formed between the protective layer and the photosensitive layer can be determined by observing the cross-section of the photoreceptor with an electron microscope or the like. If an intermediate layer can be confirmed between the protective layer and the photosensitive layer, the components of this intermediate layer can be analyzed using IR (infrared spectroscopy) or the like. If both components of the protective layer and the photosensitive layer are detected, it can be determined that a mixed layer has been formed.

[0170] <<This image forming apparatus>> An image forming apparatus ("this image forming apparatus") can be constructed using this electrophotographic photoreceptor.

[0171] As shown in Figure 1, this image forming apparatus comprises an electrophotographic photoreceptor 1, a charging device 2, an exposure device 3, and a developing device 4. Furthermore, a transfer device 5, a cleaning device 6, and a fixing device 7 are provided as needed. The electrophotographic photoreceptor 1 is not particularly limited as long as it is the electrophotographic photoreceptor described above. As an example, Figure 1 shows a drum-shaped photoreceptor in which the photosensitive layer described above is formed on the surface of a cylindrical conductive support. The charging device 2, exposure device 3, developing device 4, transfer device 5, and cleaning device 6 are arranged along the outer surface of the electrophotographic photoreceptor 1, respectively.

[0172] Examples of charging devices 2 include non-contact corona charging devices such as Corotron and Scorotron, or contact-type charging devices (direct charging devices) that charge a photoreceptor surface by bringing a voltage-applied charging component into contact with it. Examples of contact-type charging devices include charging rollers and charging brushes. In Figure 1, a roller-type charging device (charging roller) is shown as an example of charging device 2.

[0173] The exposure device 3 is not particularly limited in type, as long as it is capable of exposing the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Alternatively, exposure may be performed using an internal exposure method for the photoreceptor. The light used for exposure is arbitrary.

[0174] The type of toner T is arbitrary; in addition to powdered toner, polymerized toners using methods such as suspension polymerization or emulsion polymerization can be used.

[0175] The configuration of the developing device 4 is also arbitrary. The developing device 4 shown in Figure 1 has a configuration in which toner T is thinned by a regulating member (developing blade) 45, triboelectrically charged to a predetermined polarity, and transported while supported on a developing roller 44 to bring into contact with the surface of the photoreceptor 1. However, it is not limited to this configuration. The transfer device 5 is not particularly limited in type, and any device using any method such as electrostatic transfer methods (corona transfer, roller transfer, belt transfer, etc.), pressure transfer methods, adhesive transfer methods, etc. can be used.

[0176] There are no particular restrictions on the cleaning device 6. For example, any cleaning device such as a brush cleaner or blade cleaner can be used. If there is little or almost no toner remaining on the photoreceptor surface, the cleaning device 6 may not be necessary. The configuration of the fixing device 7 is also arbitrary. In addition to the above-described configuration, the image forming apparatus may also be configured to perform, for example, an electrostatic discharge process.

[0177] Furthermore, the image forming apparatus may be further modified in its configuration. For example, it may be configured to perform processes such as a pre-exposure process and an auxiliary charging process, or to perform offset printing, or it may be configured as a full-color tandem system using multiple types of toner.

[0178] <<This electronic photo cartridge>> This electrophotographic photoreceptor 1 can be combined with one or more of the charging device 2, exposure device 3, developing device 4, transfer device 5, cleaning device 6, and fixing device 7 to form an integrated cartridge (referred to as "this electrophotographic cartridge").

[0179] This electrophotographic cartridge can be configured to be detachable from the main body of an electrophotographic device such as a copier or laser beam printer. In that case, for example, if the electrophotographic photoreceptor 1 or other components deteriorate, the electrophotographic photoreceptor cartridge can be removed from the main body of the image forming apparatus and a new electrophotographic photoreceptor cartridge can be installed in the main body of the image forming apparatus, making maintenance and management of the image forming apparatus easier.

[0180] <<Explanation of terms>> In this invention, when expressed as "X~Y" (where X and Y are any numbers), unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as the meaning of "preferably greater than X" or "preferably less than Y." Furthermore, when we use expressions like "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number), we also imply that "greater than X is preferable" or "less than Y is preferable." [Examples]

[0181] Embodiments of the present invention will be described in more detail below with reference to examples. However, the following examples are provided to illustrate the present invention in detail, and the present invention is not limited to the examples shown below, and can be modified and implemented as desired, without departing from the spirit of the invention. In addition, in the following examples and comparative examples, the term "parts" refers to "parts by mass" unless otherwise specified.

[0182] (Preparation of coating solution P1 for forming the undercoat layer) Powder X-ray diffraction using CuKα rays showed a clear peak at a diffraction angle of 2θ = 27.3° ± 0.2°. 20 parts of D-type titanyl phthalocyanine and 280 parts of 1,2-dimethoxyethane were mixed and ground in a sand grind mill for 2 hours to perform micronization and dispersion. To this, 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 added and mixed to prepare coating solution P1 for forming the undercoat layer.

[0183] (Preparation of coating solution Q1 for forming a single-layer photosensitive layer) Powder X-ray diffraction using CuKα rays showed a clear peak at the diffraction angle 2θ = 27.3° ± 0.2°. 2.6 parts of D-type titanyl phthalocyanine, 1.3 parts of perylene pigment 1 with the structure described below, 0.5 parts of polyvinyl butyral resin, 100 parts of the hole transport substance (HTM48, molecular weight 748), 60 parts of the electron transport substance (ET-2, molecular weight 424.2), 100 parts of polycarbonate resin having a biphenyl structure, and 0.05 parts of silicone oil (Shin-Etsu Silicone Co., Ltd.: product name KF-96) as a leveling agent were mixed with 793.35 parts of a mixed solvent of tetrahydrofuran (hereinafter abbreviated as THF as appropriate) and toluene (hereinafter abbreviated as TL as appropriate) (THF 80% by mass, TL 20% by mass) to prepare a single-layer photosensitive coating solution Q1 with a solid content of 25% by mass.

[0184] TIFF0007896636000021.tif32170

[0185] TIFF0007896636000022.tif39170

[0186] TIFF0007896636000023.tif57170

[0187] (Preparation of protective layer forming coating solution S1) A curable compound M1 (product name TMPT, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), having the structure and characteristics shown in Table 1, which had been previously dissolved in a mixed solvent of methanol / 1-propanol / toluene, was mixed with a slurry of titanium dioxide particles (average primary particle size 40 nm, surface treated with 7% by mass of 3-methacryloyloxypropyltrimethoxysilane) as polymerization initiators to obtain a protective layer forming coating solution S1 (solid content concentration 27.0% by mass) with a solvent composition of methanol / 1-propanol / toluene (mass ratio) = 100 / 100 / 1 / 2. The characteristics of the curable compound M1 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0188] [TMPT] TIFF0007896636000024.tif30170

[0189] (Preparation of coating solution S2 for forming a protective layer) A protective layer forming coating solution S2 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M2 (product name GLY-9E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M1 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule. In the structural formula below, R represents an oxyalkylene group -O-CH2-CH2-, and the number of these groups, l+m+n, is 9.

[0190] [GLY-9E] TIFF0007896636000025.tif50170

[0191] (Preparation of protective layer forming coating solution S3) A protective layer forming coating solution S3 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M3 (product name TM-4E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M3 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0192] [TM-4E] The compound represented by the general formula (1') above. However, in general formula (1'), R is always an oxyalkylene group represented by -O-CH2-CH2-, l+m+n+o=4, Q is the same as in formula (3'), Z 1 These are all methyl groups.

[0193] (Preparation of protective layer forming coating solution S4) A protective layer forming coating solution S4 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M4 (product name TM-4P, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M4 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0194] [TM-4P] The compound represented by the general formula (1') above. However, in general formula (1'), R is always an oxyalkylene group represented by -O-CH(CH3)-CH2-, l+m+n+o=4, Q is the same as in formula (3'), Z 1 These are all methyl groups.

[0195] (Preparation of coating solution S5 for forming a protective layer) A protective layer forming coating solution S5 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M5 (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name M-DPH-6E), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M5 used are shown in Table 1, including molecular weight (X), number of acryloyl and methacryloyl groups in one molecule (Y), functional group equivalent (X / Y), and number of oxyalkylene groups in one molecule.

[0196] [M-DPH-6E] The compound represented by the general formula (2') above. However, in general formula (2'), R is always an oxyalkylene group represented by -O-CH2-CH2-, f+g+h+i+j+k=6, Q is a hydroxyl group or the above formula (3'), Z 1 These are all methyl groups.

[0197] (Preparation of coating solution S6 for forming a protective layer) A protective layer forming coating solution S6 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M6 (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name M-DPH-12E), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M6 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0198] [M-DPH-12E] The compound represented by the general formula (2') above. However, in general formula (2'), R is always an oxyalkylene group represented by -O-CH2-CH2-, f+g+h+i+j+k=12, Q is a hydroxyl group or the above formula (3'), Z 1 These are all methyl groups.

[0199] (Preparation of protective layer forming coating solution S7) A protective layer forming coating solution S7 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M7 (manufactured by Shin Nakamura Chemical Industry Co., Ltd., product name ATM-35E), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M7 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0200] [ATM-35E] The compound represented by the general formula (1') above. However, in general formula (1'), R is always an oxyalkylene group represented by -O-CH2-CH2-, l+m+n+o=35, Q is a hydroxyl group or the above formula (3'), Z 1 These are all hydrogen atoms.

[0201] (Preparation of coating solution S8 for forming a protective layer) A protective layer forming coating solution S8 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M8 (product name SR494, manufactured by Arkema, Inc.), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M8 used are shown in Table 1, including its molecular weight (X), the number of acryloyl and methacryloyl groups in one molecule (Y), the functional group equivalent (X / Y), and the number of oxyalkylene groups in one molecule.

[0202] [SR494] The compound represented by the general formula (1') above. However, in general formula (1'), R is always an oxyalkylene group represented by -O-CH2-CH2-, l+m+n+o=4, Q is a hydroxyl group or the above formula (3'), Z 1 These are all hydrogen atoms.

[0203] (Preparation of coating solution S9 for forming a protective layer) A protective layer forming coating solution S9 (solid content concentration 27.0% by mass) was obtained in the same manner as the protective layer forming coating solution S1, except that a curable compound M9 (manufactured by Nippon Kayaku Co., Ltd., product name KAYARAD DPCA-120), which has the structure and characteristics shown in Table 1, was used instead of the aforementioned curable compound M1. The characteristics of the curable compound M9 used are: molecular weight (X), number of acryloyl and methacryloyl groups in one molecule (Y), functional group equivalent (X / Y), and -O-(C=O)-(CH2) in one molecule. p The number of units represented by - is shown in Table 1.

[0204] [KAYARAD DPCA-120] The compound represented by the general formula (2') above. However, in the general formula (2’), all of the Rs are groups represented by -O-(C=O)-(CH2)5-, f + g + h + i + j + k = 12, Q is a hydroxy group or the formula (3’), and Z 1 are all hydrogen atoms.

[0205] <Fabrication of Single-Layer Photoreceptor> A single-layer photoreceptor was fabricated according to the following procedure.

[0206] [Comparative Example 1] A 30 mmφ, 244 mm long aluminum cylinder with a machined surface was dip-coated with the undercoat layer forming coating liquid P1, and an undercoat layer was provided such that the film thickness after drying was 0.3 μm. The single-layer photoreceptor layer forming coating liquid Q1 was dip-coated on the undercoat layer and dried at 125°C for 24 minutes, and a single-layer photoreceptor layer was provided such that the film thickness after drying was 30 μm. The protective layer forming coating liquid S1 was ring-coated on the single-layer photoreceptor layer, dried at 50°C for 5 minutes, and then, while rotating the photoreceptor at 60 rpm in a nitrogen atmosphere, irradiated with LED light of 365 nm at an intensity of 1.3 W / cm 2 for 2 minutes to provide a protective layer such that the film thickness after curing was 2 μm, and the photoreceptor A1 was fabricated.

[0207] [Comparative Example 2] A photoreceptor A2 was fabricated in the same manner as the photoreceptor A1, except that the protective layer forming coating liquid S1 was changed to the protective layer forming coating liquid S2.

[0208] [Example 1] A photoreceptor A3 was fabricated in the same manner as the photoreceptor A1, except that the protective layer forming coating liquid S1 was changed to the protective layer forming coating liquid S3.

[0209] [Example 2] A photoreceptor A4 was fabricated in the same manner as the photoreceptor A1, except that the protective layer forming coating liquid S1 was changed to the protective layer forming coating liquid S4.

[0210] [Example 3] Photoreceptor A5 was manufactured in the same manner as photoreceptor A1, except that protective layer forming coating liquid S1 was changed to protective layer forming coating liquid S5.

[0211] [Example 4] Photoreceptor A6 was manufactured in the same manner as photoreceptor A1, except that protective layer forming coating liquid S1 was changed to protective layer forming coating liquid S6.

[0212] [Comparative Example 3] Photoreceptor A7 was manufactured in the same manner as photoreceptor A1, except that protective layer forming coating liquid S1 was changed to protective layer forming coating liquid S7.

[0213] [Comparative Example 4] Photoreceptor A8 was manufactured in the same manner as photoreceptor A1, except that protective layer forming coating liquid S1 was changed to protective layer forming coating liquid S8.

[0214] [Comparative Example 5] Photoreceptor A9 was prepared in the same manner as photoreceptor A1, except that protective layer forming coating solution S1 was changed to protective layer forming coating solution S9.

[0215] <Measurement of Martens hardness and elastic deformation rate> The photoreceptors A1 to A9 obtained in the examples and comparative examples were measured from the surface side of the photoreceptor using a microhardness tester (Fischer: FISCHERSCOPE HM2000) under the following measurement conditions at a temperature of 25°C and a relative humidity of 50%. The Martens hardness and elastic deformation rate of each sample are shown in Table 1.

[0216] (Measurement conditions for Martens hardness and elastic deformation) Indenter: Vickers square pyramidal diamond indenter with a 136° face angle. Maximum indentation load: 0.2mN Load time: 10 seconds Unloading time: 10 seconds

[0217] The Martens hardness can be calculated using the following formula. Martens hardness (N / mm 2) = Maximum indentation load / Indentation area at maximum indentation load

[0218] The elastic deformation rate is a value defined by the following formula, and represents the ratio of the work done by the membrane elastically during unloading to the total work required for indentation. Elastic deformation rate (%) = (We / Wt) × 100 In the above formula, the total work Wt (nJ) represents the area enclosed by ABDA in Figure 2, and the work of elastic deformation We (nJ) represents the area enclosed by CBDC. The larger the elastic deformation rate, the less residual deformation remains under load, and an elastic deformation rate of 100 means that no deformation remains. In this example, the Martens hardness is 230 N / mm². 2 The above was considered "passing," and an elastic deformation rate of 25% or higher was also considered "passing."

[0219] <Adhesion test to the photosensitive layer: Test to confirm the presence or absence of mixed layer formation> The protective layer-forming coating solutions S1 to S9 used in each example and comparative example were applied to the surface of the single-layer photosensitive layer obtained by the method described above, before the protective layer was formed. The layers were then placed in an oven at a set temperature of 50°C for 10 minutes. After that, the surface of the photosensitive layer was wiped clean, and it was checked whether any residue of the protective layer-forming coating solutions S1 to S9 remained. The layers were then evaluated according to the following criteria. If residue remains, it can be said that the mixed layer is easily formed. ○ (very good): No traces of residue. △ (good): There are some traces of adhesion, but it is not a problem for practical use. × (poor): There are traces of adhesion.

[0220] <Evaluation of electrical characteristics> The photoreceptors A1 to A9 obtained in the examples and comparative examples were left for 16 hours in an environment of 25°C and 50% relative humidity. Then, they were mounted in an electrophotographic characteristic evaluation device (described in "Fundamentals and Applications of Electrophotographic Technology, Continued," edited by the Electrophotographic Society, Corona Publishing Co., Ltd., pp. 404-405) prepared according to the measurement standards of the Electrophotographic Society, and their electrical characteristics were measured as follows through a cycle of charging, exposure, potential measurement, and static discharge. First, the grid voltage was adjusted to charge the photoreceptor so that the initial surface potential (V0) was +700V. Next, exposure light was irradiated at 1.0 μJ / cm 2 and the residual potential (VL) 30 milliseconds after irradiation was measured. The exposure light used was the light of a halogen lamp made into monochromatic light of 780 nm with an interference filter. The residual potential (VL) is shown in Table 1. The smaller the absolute value of the residual potential (VL), the better the electrical characteristics. In this example, 90V or less was regarded as "qualified".

[0221] <Evaluation of Gas Resistance> The photoreceptors A1, A3 to A5, and A7 to A9 obtained in the examples and comparative examples were left in an environment of a temperature of 32°C and a relative humidity of 80% for 16 hours, and then mounted on an electrophotographic characteristic evaluation apparatus (described in "Fundamentals and Applications of Electrophotography", edited by the Electrophotographic Society of Japan, Corona Publishing Co., Ltd., pages 404 - 405) prepared according to the electrophotographic society measurement standard. The photoreceptor was charged so that the initial surface potential (V0) was +700V, and deterioration treatment was performed on the central part of the photoreceptor by repeating charging and discharging 10,000 cycles. After the deterioration treatment, the photoreceptor was attached to a printer, and an actual printing test was carried out in an environment of a temperature of 32°C and a relative humidity of 80%. The gas resistance was evaluated by visually inspecting the images of the deteriorated part and the untreated part. The following indicators were used for the evaluation. 〇 (good): No significant change was observed in the deteriorated part. × (poor): White spots were observed in the deteriorated part.

[0222]

Table 1

[0223] <Discussion> Examples 1-4 all exhibited high Martens hardness and elastic deformation. Furthermore, Examples 1-4 all had smaller absolute values ​​of residual potential (VL) compared to Comparative Examples 1-5, confirming that they could prevent deterioration of electrical properties, such as the deterioration of residual potential properties where charge remains after exposure. In addition, adhesion tests to the photosensitive layer confirmed that Examples 1-4 all suppressed the formation of a mixed layer between the photosensitive layer and the protective layer compared to Comparative Examples 1-3 and 5. Furthermore, evaluation of gas resistance revealed that all of Examples 1-3 exhibited better gas resistance compared to Comparative Examples 3-5. Note that the curable compound M3 used in Example 1, the curable compound M5 used in Example 3, and the curable compound M6 used in Example 4 are oxyalkylene groups having 2 carbon atoms, a structure represented by formula (5), and a structure represented by formula (6) (however, Z 4 It contains the structure before polymerization of the methyl group. The curable compound M4 used in Example 2 is a carbon-3 oxyalkylene group, a structure represented by formula (5), and a structure represented by formula (6) (where Z 4 It contains the structure before polymerization of the methyl group.

[0224] The curable compounds used in the protective layers of Examples 1-4 do not have low-polarity side chains such as alkyl groups, and furthermore, they have a structure in which groups with relatively high polarity C=O bonds (e.g., acryloyl groups, methacryloyl groups) or hydroxyl groups are located on the outside of the molecule. These polar groups located on the outside have poor affinity with the relatively low-polarity photosensitive layer. Therefore, it is possible to suppress the formation of a mixed layer between the protective layer and the photosensitive layer, and as a result, it is thought that deterioration of residual potential characteristics can be prevented. Furthermore, the curable compounds used in the protective layers of Examples 1 to 4 have at least one methacryloyl group. This sterically inhibits acidic gases such as ozone from approaching the unreacted carbon-carbon double bond, thereby suppressing oxidative degradation of the carbon-carbon double bond. For this reason, it is presumed that Example 4, which was not evaluated for gas resistance, also exhibits good gas resistance (evaluation result: ○), similar to Examples 1 to 3.

[0225] Based on the results of the above examples and comparative examples, as well as the results of tests conducted by the inventors to date, it can be concluded that if the protective layer contains a polymer having the structure represented by formula (1) or (2), or a polymer having the group represented by R', the structure represented by formula (5), and the structure represented by formula (6), that is, if the protective layer is formed using a compound having the structure represented by the following formula (1') or (2'), the Martens hardness and elastic deformation rate of the photoreceptor surface will be high, while preventing deterioration of electrical properties, such as deterioration of residual potential properties where charge remains after exposure, and also providing good gas resistance.

[0226] In this case, although l+m+n+o in formula (1') is 4 in Examples 1 and 2, the formation of a mixed layer can be suppressed because it does not have a nonpolar side chain and has a polar group located at the terminal end of the molecule. Therefore, it can be considered that a similar effect can be obtained when l+m+n+o is 1 or greater. Furthermore, in Examples 1 and 2, R in formula (1') is -O-CH2-CH2- or -O-CH(CH3)-CH2-, but from the viewpoint of suppressing steric repulsion of polar groups located at the terminal end of the molecule, alkylene groups having 1 to 8 carbon atoms, oxyalkylene groups having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p -(However, it can be assumed that a similar effect can be obtained even if p is between 2 and 6). Furthermore, in Examples 1 and 2, Q in formula (1') is the same as formula (3') below, but from the viewpoint of suppressing the formation of a mixed layer by having a polar group at the terminal end of the molecule, it can be considered that a similar effect can be obtained even if a hydroxyl group is used.

[0227] Compounds having the structure represented by formula (1') below are expected to polymerize during the curing of the protective layer by reacting with reactive functional groups that bond to the double bonds at the molecular ends, thereby forming polymers with the structure represented by formula (1).

[0228] On the other hand, in Examples 3 and 4, although f+g+h+i+j+k in formula (2') is 6 or 12, the formation of a mixed layer can be suppressed because it does not have a nonpolar side chain and has a polar group located at the terminal end of the molecule. Therefore, it can be considered that a similar effect can be obtained when f+g+h+i+j+k is 1 or greater. Furthermore, in Examples 3 and 4, R in formula (2') is -O-CH2-CH2-, but from the viewpoint of suppressing steric repulsion of polar groups located at the terminal end of the molecule, alkylene groups having 1 to 8 carbon atoms, oxyalkylene groups having 1 to 8 carbon atoms, and -O-(C=O)-(CH2) p -(However, it can be assumed that a similar effect can be obtained even if p is between 2 and 6). Furthermore, in Examples 3 and 4, Q in formula (2') is either formula (3') or a hydroxyl group, and it can be considered that similar effects can be obtained in either case.

[0229] Compounds having the structure represented by formula (2') below are expected to polymerize when the protective layer hardens, as reactive functional groups bond to the double bonds at the molecular ends, resulting in a polymer having the structure represented by formula (2).

[0230] [Formula (1')] TIFF0007896636000027.tif53170

[0231] [Formula (2')] TIFF0007896636000028.tif50170

[0232] [Formula (3')] TIFF0007896636000029.tif29170

[0233] In formula (3'), Z 2 represents the bond with R in equation (1') or equation (2'). Z 1 This represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. [Explanation of Symbols]

[0234] 1. Photoreceptor (electrophotographic photoreceptor) 2. Charging device (charging roller; charging part) 3. Exposure apparatus (exposure unit) 4. Developing device (developing unit) 5 Transfer device 6. Cleaning device 7. Fixing device 41 Developer tank 42 Agitator 43 Supply roller 44 Developing roller 45 Regulating members 71 Upper fixing member (pressure roller) 72 Lower fixing member (fixing roller) 73 Heating device T Toner P Recording paper (paper, medium)

Claims

1. An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, The protective layer contains a polymer having a structure represented by the following formula (1) or (2) in an electrophotographic photoreceptor. [Formula (1)] (In formula (1), l, m, n, and o are each integers between 0 and 10, and l+m+n+o is 1 or greater. R is independently an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH 2 ) ｐ - Represents a divalent group selected from (where p is between 2 and 6). T represents a bond with any atom. Q represents a hydroxyl group or the following formula (3). Z １ Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms. [Formula (2)] (In formula (2), f, g, h, i, j, and k are integers between 0 and 10, and f+g+h+i+j+k is 1 or greater. R is independently an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH 2 ) ｐ - Represents a divalent group selected from (where p is between 2 and 6). T represents a bond with any atom. Q represents a hydroxyl group or the following formula (3). Z １ Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms. [Formula (3)] (In formula (3), Z ２ represents the bond with R in equation (1) or (2). Z １ (where T represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. T represents a bond with any atom.)

2. The electrophotographic photoreceptor according to claim 1, wherein the protective layer contains a polymer having a structure represented by the following formula (1). [Formula (1)] (In formula (1), l, m, n, and o are each an integer of 0 or more and 10 or less, and l + m + n + o is 1 or more. Each R is independently an oxyalkylene group having 1 or more and 8 or less carbon atoms, and -O-(C=O)-(CH 2 ) ｐ -(where p is 2 or more and 6 or less) represents a divalent group selected from among them. T represents a bond to an arbitrary atom. Q represents a hydroxy group or the following formula (3). Z １ each independently represents a hydrogen atom or an alkyl group having 1 or more and 4 or less carbon atoms, and at least one of them is an alkyl group having 1 or more and 4 or less carbon atoms.) [Formula (3)] (In formula (3), Z ２ represents the bond with R in equation (1) or (2). Z １ is water (Represents an elementary atom or an alkyl group with 1 to 4 carbon atoms. T represents a bond with any atom.)

3. An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, The protective layer contains a polymer of compound a having the structure represented by the following formula (1') or a polymer of compound b having the structure represented by the following formula (2'). [Formula (1')] (In formula (1'), l, m, n, and o are integers between 0 and 10, and l+m+n+o is 1 or greater. R is independently an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH 2 ) ｐ - (where p is between 2 and 6) represents a divalent group. Q represents a hydroxyl group or the following formula (3'). Z １ Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms. [Formula (2')] (In formula (2'), f, g, h, i, j, and k are integers between 0 and 10, and f+g+h+i+j+k is 1 or greater. R is independently an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH 2 ) ｐ - (where p is between 2 and 6) represents a divalent group. Q represents a hydroxyl group or the following formula (3'). Z １ Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms. [Formula (3')] (In formula (3'), Z ２ represents the bond with R in equation (1') or equation (2'). Z １ (This represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

4. An electrophotographic photoreceptor comprising a photosensitive layer and a protective layer sequentially on a conductive support, The electrophotographic photoreceptor according to claim 3, wherein the protective layer contains a polymer of compound a having a structure represented by the following formula (1'). [Formula (1')] (In formula (1'), l, m, n, and o are integers between 0 and 10, and l+m+n+o is 1 or greater. R is independently an oxyalkylene group having 1 to 8 carbon atoms, and -O-(C=O)-(CH 2 ) ｐ - (where p is between 2 and 6) represents a divalent group. Q represents a hydroxyl group or the following formula (3'). Z １ Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, with at least one of them being an alkyl group having 1 to 4 carbon atoms. [Formula (3')] (In formula (3'), Z ２ represents the bond with R in equation (1') or equation (2'). Z １ (This represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein R in formula (1), formula (2), formula (1'), or formula (2') is an oxyalkylene group having 1 to 8 carbon atoms.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, characterized in that the protective layer contains metal oxide particles.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the protective layer is a layer that has been cured by irradiation with ultraviolet light and / or visible light.

8. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the photosensitive layer is a single-layer photosensitive layer containing both a charge generating material and a charge transporting material within the same layer.

9. The electrophotographic photoreceptor according to claim 3 or 4, characterized in that the molecular weight X of compounds a and b represented by either formula (1') or (2') above, and the number Y of acryloyl groups and methacryloyl groups contained in one molecule satisfy the following formula (4). 120≦X / Y≦400 (4)

10. The electrophotographic photoreceptor according to claim 3 or 4, wherein the molecular weight of compounds a and b represented by either formula (1') or (2') is 550 or more and 1400 or less.

11. The electrophotographic photoreceptor according to any one of claims 1 to 10, wherein l, m, n, and o in formula (1) or formula (1') are each integers between 0 and 8.

12. The electrophotographic photoreceptor according to any one of claims 1 to 11, wherein l+m+n+o in formula (1) or formula (1') is 1 or more and 12 or less.

13. The electrophotographic photoreceptor according to any one of claims 1 to 12, wherein f+g+h+i+j+k in formula (2) or formula (2') is 1 or more and 18 or less.

14. An electrophotographic photoreceptor cartridge having an electrophotographic photoreceptor according to any one of claims 1 to 13.

15. An image forming apparatus having an electrophotographic photoreceptor according to any one of claims 1 to 13.

Images