Electrophotographic photoreceptor, process cartridge, and image formation device

Abstract

To provide an electrophotographic photoreceptor which is excellent in abrasion resistance, and can suppress abnormal discharge even when being charged by only a DC voltage.SOLUTION: An electrophotographic photoreceptor has an outermost layer containing a charge transport material and a binder resin, wherein the binder resin contains a polyester resin PA having an elastic deformation rate XA of 53.0% or more, and a polycarbonate resin PB having an elastic deformation rate XB lower than the elastic deformation rate XA of the polyester resin PA by 5% or more and 12% or less.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Formation of an image by electrophotography is carried out, for example, by charging the surface of a photoreceptor, forming an electrostatic image on the surface of the photoreceptor in accordance with image information, developing the electrostatic image with a developer containing toner to form a toner image, and transferring and fixing the toner image to the surface of a recording medium.

[0003] Patent Document 1 describes a photoconductor comprising: a charging means for charging the surface of the photoconductor; a developing means for developing an electrostatic latent image formed on the surface of the photoconductor with a developer by irradiating the surface with exposure light to form a developer image on the surface of the photoconductor; and a cleaning means for removing residual developer on the surface of the photoconductor by pressing the surface of the photoconductor against the photoconductor. The outermost layer of the photoconductor has a Martens hardness value of 175 to 196 N / mm. 2 The image forming unit is characterized in that the elastic deformation rate is 35 to 48% and the static friction coefficient is 0.535 or less."

[0004] Patent Document 2 discloses an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the photosensitive layer comprising a polyarylate resin having a carboxylic acid terminal value of 100 μequivalents / g or more and 500 μequivalents / g or less, and a triphenylamine compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-217598 A [Patent Document 2] JP 2014-209221 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present disclosure is to provide a charge transport material having an outermost layer containing a charge transport material and a binder resin, the binder resin having an elastic deformation rate X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is less than 5% lower or more than 12% lower than B Polycarbonate resin P having B and (b). The object of the present invention is to provide an electrophotographic photoreceptor which is superior in abrasion resistance compared to a case in which the photoreceptor contains the above-mentioned and can suppress abnormal discharge even when charged with only a DC voltage. [Means for solving the problem]

[0007] Specific means for solving the above problems include the following aspects. <1> a charge transport material and a binder resin; The binder resin has an elastic deformation rate X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is lower than 5% to 12% B Polycarbonate resin P having B and an electrophotographic photoreceptor comprising: <2> The polyester resin P A and the polycarbonate resin P B Content ratio of polyester resin P A : Polycarbonate resin P B ) is 7:3 to 3:7 by weight; <1> The electrophotographic photoreceptor according to claim 1. <3> The polyester resin P A and the polycarbonate resin P B Content ratio of polyester resin P A : Polycarbonate resin P B) is 7:3 to 5:5 by weight; <2> The electrophotographic photoreceptor according to claim 1. <4> The polyester resin P A The polyester resin includes a dicarboxylic acid unit (A) represented by the formula (A) and a diol unit (B) represented by the formula (B) described below. <1> ~ <3> 13. The electrophotographic photoreceptor according to claim 12, <5> The polycarbonate resin P B The polycarbonate resin includes a structural unit represented by the formula (PCA) described below and a structural unit represented by the formula (PCB) below. <1> ~ <4> 13. The electrophotographic photoreceptor according to claim 12,

[0008] <6> <1> ~ <5> The electrophotographic photoreceptor according to any one of the above items is provided, A process cartridge that is detachably attached to an image forming apparatus. <7> <1> ~ <5> and an electrophotographic photoreceptor according to any one of the above items. a charging device that comes into direct contact with the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor by applying only a DC voltage; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: <8> the charging device includes a charging member that charges a surface of the electrophotographic photoreceptor, and a DC voltage application unit that applies only a DC voltage to the charging member, the voltage applied from the DC voltage application unit to the charging member is −700 V or more and −300 V or less; <7> 2. The image forming apparatus according to claim 1 . Effect of the Invention

[0009] <1> , <4> or <5> According to the present invention, the charge transport material and the binder resin are contained in an outermost layer, and the binder resin has an elastic deformation rate X A Polyester resin P with 53.0% or moreA and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is less than 5% lower or more than 12% lower than B Polycarbonate resin P having B In comparison with the case where the toner particles contain the above-mentioned, an electrophotographic photoreceptor is provided which is superior in abrasion resistance and can suppress abnormal discharge even when charged with a DC voltage alone. <2> or <3> According to the invention, polyester resin P A : Polycarbonate resin P B However, compared with cases where the ratio does not satisfy the range of 7:3 to 3:7 on a mass basis, an electrophotographic photoreceptor is provided which is superior in wear resistance and can suppress abnormal discharge even when charged with only a DC voltage. <6> , <7> or <8> According to the present invention, the charge transport material and the binder resin are contained in an outermost layer, and the binder resin has an elastic deformation rate X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is less than 5% lower or more than 12% lower than B Polycarbonate resin P having B and a process cartridge or an image forming apparatus including an electrophotographic photosensitive member which has superior wear resistance and can suppress abnormal discharge even when charged by DC voltage alone, compared with a case in which the electrophotographic photosensitive member includes the above-mentioned. [Brief description of the drawings]

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

[0011] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiments, and are not intended to limit the scope of the embodiments.

[0012] In the present disclosure, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively.

[0013] In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0014] When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0015] In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0016] In the present disclosure, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0017] In the present disclosure, the term "(meth)acrylic" means either "acrylic" or "methacrylic".

[0018] In the present disclosure, unless otherwise specified, the alkyl group includes any of straight-chain, branched and cyclic alkyl groups.

[0019] <Electrophotographic photoreceptor> The electrophotographic photoreceptor according to the present disclosure has an outermost layer containing a charge transport material and a binder resin, and the binder resin has an elastic deformation rate X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is lower than 5% to 12% B Polycarbonate resin P having B Including, Hereinafter, the "electrophotographic photoreceptor" may be simply referred to as the "photoreceptor".

[0020] In order to improve the wear resistance of the photoconductor, a highly durable resin, for example, with an elastic deformation rate of X A Progress is being made in the development of technology that uses resins with a molecular weight of 53.0% or more. On the other hand, the elastic deformation rate X A Resins with a molecular weight of 53.0% or more have high durability, so that the surface of a photoconductor having an outermost layer containing this resin is not easily scraped, and discharge products may easily accumulate. In particular, when a photoconductor has a photosensitive layer whose outermost layer contains a charge transport material, if the photoconductor is charged by a DC charging method using only a direct current voltage, a local abnormal discharge phenomenon may occur, resulting in a deterioration in the image quality of the output image.

[0021] The present inventors have investigated techniques that can suppress abnormal discharge even when charged with only a DC voltage while maintaining wear resistance, and have discovered the configuration of a photoreceptor according to the present disclosure. That is, the polyester resin P is used as a binder resin contained in the outermost layer together with the charge transport material. A and polycarbonate resin P B The polyester resin P has high durability. A and polycarbonate resin P B Difference in elastic deformation rate (elastic deformation rate X A - Elastic deformation rate X BIt has been found that by setting the content of the abrasion resistance in the range of 5% or more and 12% or less, it is possible to suppress abnormal discharge even when the material is charged by only a DC voltage while maintaining wear resistance. Hereinafter, the "abnormal discharge when charged only by DC voltage" will also be referred to simply as "abnormal discharge".

[0022] In addition, the photoreceptor according to the present disclosure forms an uneven shape on the outermost layer due to the difference in elastic deformation rate between the above two types of resins when it is run on an actual machine. When a silicone component is contained in the developer, the silicone component in the developer moderately accumulates in the recesses of the outermost layer, reducing the apparent friction coefficient, which may improve the cleaning performance on the surface of the photoreceptor.

[0023] <Layer configuration> The layer structure of the photoreceptor according to this embodiment will be described below. Fig. 1 is a partial cross-sectional view showing an example of the layer structure of a photoreceptor according to the present embodiment. The photoreceptor 10A shown in Fig. 1 has a laminated photosensitive layer. The photoreceptor 10A has a structure in which an undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (a so-called function-separated photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3.

[0024] Fig. 2 is a partial cross-sectional view showing an example of the layer structure of the photoreceptor according to the present embodiment. The photoreceptor 10B shown in Fig. 2 has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are laminated in this order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5.

[0025] [Top layer] The outermost layer contains a charge transport material and a binder resin, and therefore corresponds to the charge transport layer in the multi-layer photosensitive layer or the single-layer photosensitive layer in the single-layer photosensitive layer.

[0026] [Binding resin] In the outermost layer, the binder resin has an elastic deformation rate XA Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is lower than 5% to 12% B Polycarbonate resin P having B Including, Here, polyester resin P A and polycarbonate resin P B Difference in elastic deformation rate (elastic deformation rate X A - Elastic deformation rate X B ) is 5% or more and 12% or less, and more preferably 7% or more and 10% or less.

[0027] Polyester Resin P A and polycarbonate resin P B The elastic deformation rate is calculated as follows. Here, the elastic deformation rate is defined as the total deformation amount when a load is applied to the measurement object, divided into the elastic deformation amount and the plastic deformation amount, and the elastic deformation rate is defined as the elastic deformation rate / total deformation amount. Specifically, first, a resin layer of 5 μm thickness made of resin only is obtained as the measurement object. Then, for this resin layer, the indentation depth and the indentation depth-stress curve are measured using Nanoindenter SA2 manufactured by MTS, a DCM head, and a diamond equilateral triangular pyramid indenter, and the elastic deformation rate is calculated. More specifically, the indentation depth when the indentation depth is set to 500 nm under the measurement conditions of a temperature of 24° C. and a humidity of 50% is defined as Dmax (nm), and then the indentation depth in a completely unloaded state is defined as D1 (nm), and the elastic deformation rate R of the resin layer is calculated using the following formula. The calculated elastic deformation rate R is defined as the elastic deformation rate of the resin constituting the resin layer. [Formula] Elastic deformation ratio R = (Dmax-D1) / Dmax

[0028] (Polyester Resin P A ) Hereinafter, the elastic deformation rate X A Polyester resin P is 53.0% or more A This article explains: Polyester Resin PA is the elastic deformation rate X A There are no particular restrictions as long as the ratio is 53.0% or more. Polyester Resin P A Elastic deformation rate X A is 53.0% or more, and more preferably 58.0% or more. In addition, polyester resin P A Elastic deformation rate X A The upper limit is, for example, 60.0%.

[0029] Polyester Resin P A It is preferable that the polyester resin contains a polyester resin having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B). Hereinafter, a polyester resin having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B) will be referred to as "polyester resin (1)".

[0030] [ka]

[0031] In formula (A), Ar A1 and Ar A2 each independently represents an aromatic ring which may have a substituent; L A is a single bond or a divalent linking group, n A1 is 0, 1 or 2. In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent; L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 is 0, 1 or 2. Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 1 and Rb 2may be bonded to form a cyclic alkyl group.

[0032] The polyester resin (1) may contain a dicarboxylic acid unit other than the dicarboxylic acid unit (A).The polyester resin (1) may contain a diol unit other than the diol unit (B).

[0033] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0034] [ka]

[0035] In formula (A), Ar A1 and Ar A2 each independently represents an aromatic ring which may have a substituent; L A is a single bond or a divalent linking group, n A1 is 0, 1 or 2.

[0036] Ar A1 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0037] Ar A1 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. A1 The aromatic ring of When substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0038] Ar A2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0039] Ar A2 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. A2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0040] L A When is a divalent linking group, examples of the divalent linking group include an oxygen atom, a sulfur atom, -C(Ra 1 )(Ra 2 )-, where Ra 1 and Ra 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; 1 and Ra 2 may be bonded to form a cyclic alkyl group.

[0041] Ra 1 and Ra 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0042] Ra 1 and Ra 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6.

[0043] Ra 1 and Ra 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0044] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the dicarboxylic acid unit (A1) represented by the following formula (A1), the dicarboxylic acid unit (A2) represented by the following formula (A2), the dicarboxylic acid unit (A3) represented by the following formula (A3), and the dicarboxylic acid unit (A4) represented by the following formula (A4). The dicarboxylic acid unit (A) more preferably contains at least one selected from the group consisting of the dicarboxylic acid unit (A2), the dicarboxylic acid unit (A3), and the dicarboxylic acid unit (A4), and further preferably contains the dicarboxylic acid unit (A2).

[0045] [ka]

[0046] In formula (A1), n 101 is an integer between 0 and 4, and n 101 Ra 101 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 101 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0047] [ka]

[0048] In formula (A2), n 201 and n 202 are each independently an integer of 0 to 4, 201 Ra 201 and n 202 Ra202 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 201 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 202 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0049] [ka]

[0050] In formula (A3), n 301 and n 302 are each independently an integer of 0 to 4, 301 Ra 301 and n 302 Ra 302 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. n 302 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0.

[0051] [ka]

[0052] In formula (A4), n 401 is an integer between 0 and 6, and n 401 Ra 401 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and even more preferably 0.

[0053] Ra in formula (A1) 101 , Ra in formula (A2) 201 and Ra 202 , Ra in formula (A3) 301 and Ra 302 And Ra of formula (A4) 401 Since the specific and preferred embodiments of are the same, hereinafter, Ra 101 , Ra 201 , Ra 202 , Ra 301 , Ra 302 and Ra 401 These will be collectively referred to as "Ra".

[0054] The alkyl group having 1 to 10 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. Examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of the branched alkyl group having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, and a tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl group formed by linking these monocyclic alkyl groups.

[0055] The aryl group having 6 to 12 carbon atoms related to Ra may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0056] The alkyl group in the alkoxy group having 1 to 6 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0057] Specific examples of the dicarboxylic acid unit (A1) include the following dicarboxylic acid units (A1-1) to (A1-9), but the dicarboxylic acid unit (A1) is not limited thereto.

[0058] [ka]

[0059] Specific examples of the dicarboxylic acid unit (A2) include the following dicarboxylic acid units (A2-1) to (A2-3), but the dicarboxylic acid unit (A2) is not limited thereto.

[0060] [ka]

[0061] Specific examples of the dicarboxylic acid unit (A3) include the dicarboxylic acid units (A3-1) and (A3-2), but the dicarboxylic acid unit (A3) is not limited thereto.

[0062] [ka]

[0063] Specific examples of the dicarboxylic acid unit (A4) include the following dicarboxylic acid units (A4-1) to (A4-3), but the dicarboxylic acid unit (A4) is not limited thereto.

[0064] [ka]

[0065] The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of the above specific examples (A1-1), (A1-7), (A2-3), (A3-2) and (A4-3), more preferably contains at least one selected from the group consisting of (A2-3), (A3-2) and (A4-3), and further preferably contains at least (A2-3). preferable.

[0066] The total mass proportion of the dicarboxylic acid units (A1) to (A4) in the polyester resin (1) is preferably 15 mass % or more and 60 mass % or less. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 15 mass% or more, the photosensitive layer has good abrasion resistance. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 20 mass% or more, and further preferably 25 mass% or more. When the total mass proportion of the dicarboxylic acid units (A1) to (A4) is 60 mass% or less, peeling of the photosensitive layer can be suppressed. From this viewpoint, the total mass proportion of the dicarboxylic acid units (A1) to (A4) is more preferably 55 mass% or less, and further preferably 50 mass% or less. The dicarboxylic acid units (A1) to (A4) contained in the polyester resin (1) may be of one type or of two or more types.

[0067] Examples of the dicarboxylic acid units (A) other than the dicarboxylic acid units (A1) to (A4) include aliphatic dicarboxylic acid (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid) units, alicyclic dicarboxylic acid (e.g., cyclohexanedicarboxylic acid) units, and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The dicarboxylic acid units contained in the polyester resin (1) may be of one type or two or more types.

[0068] The dicarboxylic acid unit (A) contained in the polyester resin (1) may be of one type or of two or more types.

[0069] The diol unit (B) is a structural unit represented by the following formula (B).

[0070] [ka]

[0071] In formula (B), Ar B1 and Ar B2 each independently represents an aromatic ring which may have a substituent; L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 is 0, 1 or 2. Rb 1 and Rb 2each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0072] Ar B1 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and the benzene ring and the naphthalene ring are preferred.

[0073] Ar B1 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B1 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0074] Ar B2 The aromatic ring may be either a monocyclic or polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. A naphthalene ring is preferred.

[0075] Ar B2 The hydrogen atoms on the aromatic ring of may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom, or the like. B2 When the aromatic ring is substituted, the substituent is preferably an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0076] Rb 1 and Rb 2The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 18 carbon atoms, more preferably 1 to 14 carbon atoms, and even more preferably 1 to 10 carbon atoms.

[0077] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6.

[0078] Rb 1 and Rb 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, more preferably 6.

[0079] The diol unit (B) preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8).

[0080] It is more preferable that the diol unit (B) contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), and a diol unit (B6) represented by the following formula (B6): It is more preferable that the diol unit (B1) represented by the following formula (B1), the diol unit (B2) represented by the following formula (B2), the diol unit (B5) represented by the following formula (B5), and the diol unit (B6) represented by the following formula (B6) are contained in the diol unit (B1), It is even more preferable that the diol unit (B1) represented by the following formula (B1), the diol unit (B2) represented by the following formula (B2), and the diol unit (B6) represented by the following formula (B6) are contained in the diol unit (B1), It is most preferable that the diol unit (B1) contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1) and a diol unit (B2) represented by the following formula (B2).

[0081] [ka]

[0082] In formula (B1), Rb 101 is a branched alkyl group having 4 to 20 carbon atoms, and Rb 201 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 401 , Rb 501 , Rb 801 and Rb 901 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0083] Rb 101 The carbon number of the branched alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 101Specific examples of the aryl group include an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0084] [ka]

[0085] In formula (B2), Rb 102 is a linear alkyl group having 4 to 20 carbon atoms, and Rb 202 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 402 , Rb 502 , Rb 802 and Rb 902 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0086] Rb 102 The carbon number of the linear alkyl group having 4 to 20 carbon atoms in the formula Rb is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples of the aryl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0087] [ka]

[0088] In formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; d is an integer of 7 to 15; Rb 403 , Rb 503 , Rb 803 and Rb 903 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0089] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 213 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of the group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb 113 and Rb 213 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0090] [ka]

[0091] In formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb804 and Rb 904 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0092] Rb 104 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 or 2, and more preferably 1. 104 Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0093] [ka]

[0094] In formula (B5), Ar 105 is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, Rb 205 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 405 , Rb 505 , Rb 805 and Rb 905 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0095] Ar 105 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ar 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms is a monocyclic or The number of carbon atoms in the aryl group is preferably 6 or more and 10 or less, and more preferably 6. Examples of the aralkyl group having 7 or more and 20 or less carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathylmethyl group, and a phenyl-cyclopentylmethyl group.

[0096] [ka]

[0097] In formula (B6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; e is an integer of 4 to 6; Rb 406 , Rb 506 , Rb 806 and Rb 906 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0098] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of such groups include a methyl group, an ethyl group, and an n-propyl group. Rb 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of the group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a cyclopropoxy group, and a cyclobutoxy group. Rb116 and Rb 216 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0099] [ka]

[0100] In formula (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0101] [ka]

[0102] In formula (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0103] Rb in formula (B1) 201 , Rb in formula (B2) 202 , Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 201 , Rb 202 , Rb 204 and Rb 205 "Rb 200 " is collectively described as such.

[0104] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably has 1 carbon atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group.

[0105] Rb in formula (B1) 401 , Rb in formula (B2) 402 , Rb in formula (B3) 403 , Rb in formula (B4) 404 , Rb in formula (B5) 405 , Rb in formula (B6) 406 , Rb in formula (B7) 407 and Rb of formula (B8) 408 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 "Rb 400 " is collectively described as such.

[0106] Rb 400 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0107] Rb 400 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0108] Rb 400 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0109] Rb in formula (B1) 501 , Rb in formula (B2) 502 , Rb in formula (B3) 503 , Rb in formula (B4) 504 , Rb in formula (B5) 505 , Rb in formula (B6) 506 , Rb in formula (B7) 507 and Rb of formula (B8) 508 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 "Rb 500 " is collectively described as such.

[0110] Rb 500 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0111] Rb 500 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0112] Rb 500 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0113] Rb in formula (B1) 801 , Rb in formula (B2) 802 , Rb in formula (B3) 803 , Rb in formula (B4) 804 , Rb in formula (B5) 805 , Rb in formula (B6) 806 , Rb in formula (B7) 807 and Rb of formula (B8) 808Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 "Rb 800 " is collectively described as such.

[0114] Rb 800 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0115] Rb 800 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0116] Rb 800 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0117] Rb in formula (B1) 901 , Rb in formula (B2) 902 , Rb in formula (B3) 903 , Rb in formula (B4) 904 , Rb in formula (B5) 905 , Rb in formula (B6) 906 , Rb in formula (B7) 907 and Rb of formula (B8) 908 Since the specific and preferred forms of Rb are the same as those of Rb, Rb will be referred to as Rb in the following. 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb 907 and Rb 908 "Rb 900 " is collectively described as such.

[0118] Rb 900 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2, and even more preferably 1. Examples of the linear alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Examples of the branched alkyl group having 3 or 4 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples of the cyclic alkyl group having 3 or 4 carbon atoms include a cyclopropyl group and a cyclobutyl group.

[0119] Rb 900The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0120] Rb 900 Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0121] Specific examples of the diol unit (B1) include diol units (B1-1) to (B1-6), but the diol unit (B1) is not limited thereto.

[0122] [ka]

[0123] Specific examples of the diol unit (B2) include the diol units (B2-1) to (B2-11), but the diol unit (B2) is not limited thereto.

[0124] [ka]

[0125] Specific examples of the diol unit (B3) include diol units (B3-1) to (B3-4), but the diol unit (B3) is not limited thereto.

[0126] [ka]

[0127] Specific examples of the diol unit (B4) include the diol units (B4-1) to (B4-7), but the diol unit (B4) is not limited thereto.

[0128] [ka]

[0129] Specific examples of the diol unit (B5) include the diol units (B5-1) to (B5-6), but the diol unit (B5) is not limited thereto.

[0130] [ka]

[0131] Specific examples of the diol unit (B6) include the diol units (B6-1) to (B6-4), but the diol unit (B6) is not limited thereto.

[0132] [ka]

[0133] Specific examples of the diol unit (B7) include diol units (B7-1) to (B7-3), but the diol unit (B7) is not limited thereto.

[0134] [ka]

[0135] Specific examples of the diol unit (B8) include the diol units (B8-1) to (B8-3), but the diol unit (B8) is not limited thereto.

[0136] [ka]

[0137] The diol unit (B) contained in the polyester resin (1) may be of one type or of two or more types.

[0138] The mass proportion of the diol unit (B) in the polyester resin (1) is preferably 25 mass % or more and 80 mass % or less. When the mass proportion of the diol unit (B) is 25 mass% or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 30 mass% or more, and further preferably 35 mass% or more. When the mass proportion of the diol unit (B) is 80 mass% or less, the solubility in the coating solution for forming the photosensitive layer can be maintained and the abrasion resistance can be improved. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 75 mass% or less, and further preferably 70 mass% or less.

[0139] Examples of the diol units other than the diol units (B) include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0140] The ends of the polyester resin (1) may be capped or modified with an end-capping agent or a molecular weight regulator used during production. Examples of the end-capping agent or the molecular weight regulator include a monohydric phenol, a monovalent acid chloride, a monohydric alcohol, and a monovalent carboxylic acid. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, 2 ... Phenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, 2-phenyl-2-(3-hydroxyphenyl)propane (1) propane. Examples of the monovalent acid chloride include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetic acid chloride, butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and substituted versions of these. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monovalent carboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0141] The weight average molecular weight of the polyester resin (1) is preferably from 30,000 to 300,000, more preferably from 40,000 to 250,000, and even more preferably from 50,000 to 200,000. The molecular weight of the polyester resin (1) is a polystyrene-equivalent molecular weight measured by gel permeation chromatography (GPC), which uses tetrahydrofuran as an eluent.

[0142] The polyester resin (1) can be obtained by polycondensing a monomer that gives a dicarboxylic acid unit (A) and a monomer that gives a diol unit (B) with other monomers as required by a conventional method. Examples of the method for polycondensing a monomer include an interfacial polymerization method, a solution polymerization method, and a melt polymerization method. The interfacial polymerization method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent that is not compatible with water with a dihydric alcohol dissolved in an alkaline aqueous solution. Examples of literature related to the interfacial polymerization method include WME ARECSON, J. Poly. Sci., XL399, 1959, and JP-B-1959. The interfacial polymerization method has a faster reaction rate than the solution polymerization method, and therefore can suppress hydrolysis of the dicarboxylic acid halide, resulting in a polyester resin with a high molecular weight.

[0143] (Polycarbonate resin P B ) Hereinafter, polycarbonate resin P B This article explains: Polycarbonate Resin P B is the polyester resin P used in combination A Difference in elastic deformation rate (elastic deformation rate X A - Elastic deformation rate X B ) is not particularly limited as long as it is in the range of 5% or more and 12% or less.

[0144] Polycarbonate Resin P B It is preferable that the polycarbonate resin contains a constitutional unit represented by the following formula (PCA) and a constitutional unit represented by the following formula (PCB). A polycarbonate resin having a constitutional unit represented by the following formula (PCA) and a constitutional unit represented by the following formula (PCB) is simply referred to as polycarbonate resin (2).

[0145] [ka]

[0146] In the formula (PCA), R P1 and R P2 each independently represents a hydrogen atom, a halogen atom, an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 5 to 7 carbon atoms, or an aryl group having from 6 to 12 carbon atoms. In the formula (PCB), R P3 and R P4 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms. P1 represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group.

[0147] In the formula (PCA) and the formula (PCB), R P1 , R P2 , R P3 , and R P4 The alkyl group represented by the formula (I) includes a linear or branched alkyl group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms). Specific examples of the straight-chain alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Specific examples of branched alkyl groups include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, and a tert-hexyl group. Among these, the alkyl group is preferably a lower alkyl group such as a methyl group or an ethyl group.

[0148] In the formula (PCA) and the formula (PCB), R P1 , R P2 , R P3 , and R P4 Examples of the cycloalkyl group represented by the formula (I) include cyclopentyl, cyclohexyl, and cycloheptyl.

[0149] In the formula (PCA) and the formula (PCB), R P1 , R P2 , R P3 , and R P4 Examples of the aryl group represented by the formula (I) include a phenyl group, a naphthyl group, and a biphenylyl group.

[0150] In the formula (PCA) and the formula (PCB), X P1 The alkylene group represented by the formula (I) includes a linear or branched alkylene group having 1 to 12 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms). Specific examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-undecylene group, and an n-dodecylene group. Specific examples of branched alkylene groups include isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, neopentylene, tert-pentylene, isohexylene, sec-hexylene, tert-hexylene, isoheptylene, sec-heptylene, tert-heptylene, isooctylene, sec-octylene, tert-octylene, isononylene, sec-nonylene, tert-nonylene, isodecylene, sec-decylene, tert-decylene, isoundecylene, sec-undecylene, tert-undecylene, neoundecylene, isododecylene, sec-dodecylene, tert-dodecylene, and neododecylene. Among these, the alkylene group is preferably a lower alkyl group such as a methylene group, an ethylene group, or a butylene group.

[0151] In the formula (PCA) and the formula (PCB), X P1 The cycloalkylene group represented by the formula (I) includes a cycloalkylene group having 3 to 12 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 8 carbon atoms). Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and a cyclododecanyl group. Of these, the cycloalkyl group is preferably a cyclohexyl group.

[0152] In addition, in the formula (PCA) and the formula (PCB), R P1 , R P2 , R P3 , R P4 , and X P1 Each of the above-mentioned substituents represented by also includes groups having a further substituent. Examples of the substituent include a halogen atom (e.g., a fluorine atom, a chlorine atom), an alkyl group (e.g., an alkyl group having 1 to 6 carbon atoms), a cycloalkyl group (e.g., a cycloalkyl group having 5 to 7 carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 to 4 carbon atoms), and an aryl group (e.g., a phenyl group, a naphthyl group, a biphenylyl group, etc.).

[0153] In the formula (PCA), R P1 , and R P2 each independently preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R P1 , and R P2 More preferably, represents a hydrogen atom. In the formula (PCB), R P3 , and R P4 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; X P1 It is preferred that represents an alkylene group or a cycloalkylene group.

[0154] Specific examples of the polycarbonate resin (2) include, but are not limited to, the following: In the example compounds, pm and pn indicate the copolymerization ratio.

[0155] [ka]

[0156] Here, in the polycarbonate resin (2), the content (copolymerization ratio) of the structural unit represented by formula (PCA) is preferably in the range of 5 mol % or more and 95 mol % or less with respect to all structural units constituting the polycarbonate resin, and from the viewpoint of suppressing uneven density of a grainy image, it is preferably in the range of 5 mol % or more and 50 mol % or less, and more preferably in the range of 15 mol % or more and 30 mol % or less. Specifically, in the above-mentioned exemplary compounds of the polycarbonate resin (2), pm and pn indicate a copolymerization ratio (molar ratio), and pm:pn is in the range of 95:5 to 5:95, 50:50 to 5:95, and more preferably 15:85 to 30:70.

[0157] In order to suppress abnormal discharge while maintaining wear resistance, the polyester resin P in the outermost layer is A and polycarbonate resin P B Content ratio of polyester resin PA : Polycarbonate resin P B ) is preferably 7:3 to 3:7, and more preferably 7:3 to 5:5, on a mass basis.

[0158] [Charge transport material] As the charge transport material, the same charge transport material as in the charge transport layer described below can be used.

[0159] Hereinafter, the members or layers other than the outermost layer of the electrophotographic photoreceptor according to the present embodiment will be described in detail, with the reference numerals being omitted.

[0160] [Conductive Substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a material having a volume resistivity of 10 13 This means that the resistance is less than Ωcm.

[0161] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiating with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate since it suppresses the occurrence of defects due to unevenness on the surface.

[0162] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0163] As a method for roughening the surface, there can be mentioned a method in which, without roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0164] In the roughening treatment by anodization, an oxide film is formed on the surface of a conductive substrate made of metal (e.g., aluminum) by anodizing the substrate in an electrolyte solution using the substrate as the anode. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodization is chemically active in its original state, easily contaminated, and has a large resistance variation depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are filled by volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel may be added) to change the film into a more stable hydrated oxide.

[0165] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm. If the thickness is within this range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0166] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acid treatment liquid is carried out, for example, as follows. First, an acid treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acid treatment liquid are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42° C. to 48° C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0167] The boehmite treatment is carried out, for example, by immersing the plate in pure water at 90° C. to 100° C. for 5 to 60 minutes, or by contacting the plate with heated steam at 90° C. to 120° C. for 5 to 60 minutes. The thickness of the coating is preferably 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution having low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0168] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0169] As inorganic particles, for example, powder resistivity (volume resistivity) of 10 2 Ωcm or more 10 11 Examples of such particles include inorganic particles with a particle size of Ωcm or less. Among these, examples of inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0170] The specific surface area of ​​inorganic particles by the BET method is, for example, 10 m 2 / g or higher is preferable. The volume average particle size of the inorganic particles is, for example, from 50 nm to 2000 nm (preferably from 60 nm to 1000 nm).

[0171] The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0172] The inorganic particles may be surface-treated. Two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0173] Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, etc. In particular, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0174] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0175] Silane coupling agents may be used in combination of two or more kinds. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0176] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

[0177] The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

[0178] Here, it is preferable that the undercoat layer contains an electron accepting compound (acceptor compound) together with the inorganic particles, from the viewpoints of improving the long-term stability of electrical properties and carrier blocking properties.

[0179] Examples of the electron-accepting compound include electron-transporting substances such as quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds. In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and more specifically, anthraquinone, alizarin, quinizarin, anthrarufin, and purpurin.

[0180] The electron accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surfaces of the inorganic particles.

[0181] The method for attaching the electron accepting compound to the surface of the inorganic particles may be, for example, a dry method or a wet method.

[0182] The dry method is, for example, a method in which an electron-accepting compound is attached to the surface of inorganic particles by dropping an electron-accepting compound directly or dissolved in an organic solvent or spraying it together with dry air or nitrogen gas while stirring inorganic particles with a mixer or the like that exerts a large shearing force. The dropping or spraying of the electron-accepting compound is preferably performed at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100° C. or higher. The temperature and time of baking are not particularly limited as long as electrophotographic properties can be obtained.

[0183] The wet method is a method in which, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and the inorganic particles are stirred or dispersed, and then the solvent is removed to attach the electron-accepting compound to the surface of the inorganic particles. The solvent is removed, for example, by filtration or distillation. After the solvent is removed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound, and examples of such methods include a method of removing the moisture while stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0184] The attachment of the electron accepting compound may be carried out before or after the inorganic particles are subjected to a surface treatment with a surface treatment agent, or the attachment of the electron accepting compound and the surface treatment with the surface treatment agent may be carried out simultaneously.

[0185] The content of the electron accepting compound is, for example, from 0.01% by mass to 20% by mass, and preferably from 0.01% by mass to 10% by mass, based on the inorganic particles.

[0186] Examples of the binder resin used in the undercoat layer include known materials such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents. Examples of the binder resin used in the undercoat layer include charge transporting resins having charge transporting groups, conductive resins (such as polyaniline, etc.), and the like.

[0187] Among these, the binder resin used in the undercoat layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and in particular, a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, and epoxy resins, with a curing agent is preferred. When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0188] The undercoat layer may contain various additives for improving electrical properties, environmental stability, and image quality. Examples of the additives include known materials such as polycyclic condensation and azo-based electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As described above, silane coupling agents are used for surface treatment of inorganic particles, and may also be added to the undercoat layer as an additive.

[0189] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like.

[0190] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0191] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0192] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0193] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0194] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used in order to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, grinding, and the like.

[0195] The formation of the undercoat layer is not particularly limited, and a well-known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating solution for forming the undercoat layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary.

[0196] Examples of the solvent for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0197] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming the undercoat layer include known methods such as those using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0198] Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0199] The thickness of the undercoat layer is set, for example, preferably at least 15 μm, and more preferably within the range of from 20 μm to 50 μm.

[0200] [Middle class] Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0201] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0202] The formation of the intermediate layer is not particularly limited, and a well-known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating liquid for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it if necessary. The intermediate layer can be formed by any of the usual coating methods, such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating.

[0203] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm. The intermediate layer may also be used as an undercoat layer.

[0204] [Charge Generation Layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may also be a vapor deposition layer of the charge generation material. The vapor deposition layer of the charge generation material is suitable for use with a non-coherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0205] Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0206] Among these, in order to accommodate laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material, specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine.

[0207] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include condensed aromatic pigments such as dibromoanthanthrone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and bisazo pigments.

[0208] The above charge generating materials may be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm, but from the viewpoint of resolution, when using a thin photosensitive layer of 20 μm or less, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate, so-called black spots, is likely to occur as an image defect. This becomes more noticeable when using charge generating materials that are p-type semiconductors such as trigonal selenium and phthalocyanine pigments and are prone to generating dark current.

[0209] In contrast, when an n-type semiconductor such as a fused aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is unlikely to occur, and image defects called black spots can be suppressed even when the material is made into a thin film. The n-type is determined by the polarity of the photocurrent that flows using the commonly used time-of-flight method, and those that easily pass electrons as carriers rather than holes are considered to be n-type.

[0210] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, and the like. Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensation product of bisphenols and aromatic dicarboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, etc. Here, "insulating" means a material having a volume resistivity of 10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0211] The compounding ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 by mass.

[0212] The charge generating layer may contain other well-known additives.

[0213] The formation of the charge generation layer is not particularly limited, and a known formation method is used, for example, by forming a coating film of a coating solution for forming a charge generation layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary. The formation of the charge generation layer may be performed by vapor deposition of a charge generation material. The formation of the charge generation layer by vapor deposition is particularly suitable when a condensed ring aromatic pigment or a perylene pigment is used as the charge generation material.

[0214] Examples of the solvent for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0215] Examples of methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming a charge generating layer include media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion liquid is dispersed by penetrating a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0216] Examples of a method for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0217] The thickness of the charge generating layer is set, for example, preferably in the range of 0.1 μm or more and 5.0 μm or less, and more preferably in the range of 0.2 μm or more and 2.0 μm or less.

[0218] [Charge transport layer] The charge transport layer is a layer containing a charge transport material and a binder resin, and may be a layer containing a polymer charge transport material.

[0219] Examples of the charge transport material include electron transporting compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of the charge transport material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0220] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

[0221] [ka]

[0222] In structural formula (a-1), Ar T1 , Ar T2 , and Ar T3 each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -CH-CH=CH-CH=C(R T7 )(R T8 ) is shown. T4 , RT5 , R T6 , R T7 , and R T8 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0223] [ka]

[0224] In structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 each independently represents a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, an amino group substituted with an alkyl group having from 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) and R T12 , R T13 , R T14 , R T15 and R T16 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0225] Among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 ) is preferable from the viewpoint of charge mobility.

[0226] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0227] The binder resin used in the charge transport layer is the polyester resin P A and polycarbonate resin P B In addition, other resins may be contained within a range that does not impair the effects of wear resistance and suppression of abnormal discharge. Other resins include polycarbonate resin P B Other than polycarbonate resin, polyester resin P A Other examples of the binder resin include polyester resins, polyarylate resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, and polysilanes. Among these, polycarbonate resins or polyarylate resins are suitable as the binder resin. These other resins are used alone or in combination of two or more.

[0228] The compounding ratio of the charge transport material to the binder resin is preferably from 10:1 to 1:5 by mass.

[0229] The charge transport layer may contain other well-known additives.

[0230] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0231] Examples of solvents for preparing the coating liquid for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination of two or more.

[0232] Examples of a coating method for coating the coating liquid for forming the charge transport layer on the charge generating layer include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating and curtain coating.

[0233] The thickness of the charge transport layer is set, for example, preferably in the range of 5 μm or more and 50 μm or less, and more preferably in the range of 10 μm or more and 30 μm or less.

[0234] [Single-layer type photosensitive layer] The single-layer type photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material, a charge transport material, a binder resin, and, if necessary, other well-known additives. Note that these materials are the same as those described for the outermost layer, the charge generation layer, and the charge transport layer. In the single-layer photosensitive layer, the content of the charge generating material is preferably from 0.1% by mass to 10% by mass, more preferably from 0.8% by mass to 5% by mass, based on the total solid content. In the single-layer photosensitive layer, the content of the charge transport material is preferably 5% by mass or more and 50% by mass or less based on the total solid content. The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generating layer and the charge transport layer. The thickness of the single-layer photosensitive layer is, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 40 μm or less.

[0235] <Image forming apparatus (and process cartridge)> The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging device for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to the present embodiment is used as the electrophotographic photoreceptor, and the charging device is a charging device that comes into direct contact with the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor by applying only a DC voltage.

[0236] In the image forming apparatus according to the present embodiment, the charging device has a charging member that charges the surface of the electrophotographic photosensitive member, and a DC voltage application section that applies only a DC voltage to the charging member, and it is preferable that the voltage applied from the DC voltage application section to the charging member is −700 V or more and −300 V or less (more preferably −650 V or more and −450 V or less). Even under such charging conditions, abnormal discharge can be effectively suppressed.

[0237] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus provided with a fixing device that fixes a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type that directly transfers a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type that performs primary transfer of a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member and secondary transfer of the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus provided with a cleaning device that cleans the surface of an electrophotographic photosensitive member before charging after the transfer of a toner image; an apparatus provided with a static elimination device that irradiates the surface of an electrophotographic photosensitive member with static elimination light to eliminate static electricity before charging after the transfer of a toner image; and an apparatus provided with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0238] In the case of an intermediate transfer type device, the transfer device is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer device which primarily transfers the toner image formed on the surface of an electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer device which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0239] The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (a development type using a liquid developer).

[0240] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may be a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including an electrophotographic photosensitive member according to the present embodiment is preferably used. In addition to the electrophotographic photosensitive member, the process cartridge may include at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0241] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of the rest will be omitted.

[0242] FIG. 3 is a schematic diagram showing an example of an image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, and the intermediate transfer body 50 is disposed with a part of it in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer device.

[0243] 3 supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) integrally within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0244] FIG. 3 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists in cleaning, which may be arranged as needed.

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

[0246] -Charging device- The charging device 8 preferably includes a charging member that is provided in contact with the surface of the photoconductor and charges the surface of the photoconductor, and a power source (an example of a voltage application section) that applies a charging voltage to the charging member. As described above, the power source is preferably a DC voltage application section that applies only a DC voltage to the charging member. Furthermore, the voltage applied from the power source, which is the DC voltage application section, to the charging member is preferably -700V or more and -300V or less (more preferably -650V or more and -450V or less).

[0247] The charging member in the charging device 8 may be, for example, a contact type charger using a conductive charging roll, a charging brush, a charging film, a charging rubber blade, a charging tube, or the like.

[0248] -Exposure equipment- The exposure device 9 may be, for example, an optical device that exposes the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. The wavelength of the semiconductor laser is mainly near infrared light having an oscillation wavelength of about 780 nm. However, it is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a blue laser having an oscillation wavelength of 400 nm to 450 nm may also be used. In addition, a surface-emitting laser light source capable of outputting multiple beams is also effective for forming a color image.

[0249] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contacting or non-contacting a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected according to the purpose. For example, it may be a known developing device that has a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, roller, or the like. Among them, it is preferable to use a developing roller that holds a developer on its surface.

[0250] The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Well-known developers are used.

[0251] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131 . In addition to the cleaning blade system, a fur brush cleaning system or a simultaneous development and cleaning system may also be used.

[0252] -Transfer device- Examples of the transfer device 40 include known transfer chargers such as a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0253] -Intermediate transfer body- A belt-like intermediate transfer belt containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. is used as the intermediate transfer body 50. The intermediate transfer body may be in the form of a drum other than a belt.

[0254] FIG. 4 is a schematic diagram showing another example of the image forming apparatus according to the present embodiment. 4 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photosensitive body is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. EXAMPLES

[0255] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0256] In the following description, syntheses, treatments, manufactures, etc. were carried out at room temperature (25° C.±3° C.) unless otherwise specified.

[0257] <Preparation of polyester resin> Polyester resin 1 (PE1) was prepared with 50 mol% dicarboxylic acid units (A2-3) and 50 mol% diol units (B1-3). Polyester resin 2 (PE2) was prepared with 50 mol% dicarboxylic acid units (A2-3) and 50 mol% diol units (B1-4). Polyester resin 3 (PE3) was prepared with 25 mol% dicarboxylic acid units (A2-3), 25 mol% diol units (A4-3), and 50 mol% diol units (B4-4). Polyester resin 4 (PE4) was prepared with 50 mol% dicarboxylic acid units (A3-1) and 50 mol% diol units (B4-3).

[0258] <Preparation of polycarbonate resin> Polycarbonate resin 1 (PC1) having the following structure was prepared. The molar ratio of m:n in PC1 was 25:75, and the weight average molecular weight was 50,000.

[0259] [ka]

[0260] Polycarbonate resin 2 (PC2) having the following structure was prepared. The weight average molecular weight of PC2 was 50,000.

[0261] [ka]

[0262] Polycarbonate resin 3 (PC3) having the following structure was prepared. The weight average molecular weight of PC3 was 40,000.

[0263] [ka]

[0264] The elastic deformation rate of the resin was determined by the method described above. The results are shown in Table 1.

[0265] <Production of an electrophotographic photoreceptor having a laminated photosensitive layer> [Electrophotographic photoreceptor (P1)] - Formation of undercoat layer - As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm was prepared. Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 100 parts of a zinc oxide powder (100 parts by weight, manufactured by Teika Co., Ltd.) was mixed with 500 parts of toluene by stirring, and 1.3 parts of a silane coupling agent (product name: KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added thereto, followed by stirring for 2 hours. Thereafter, the toluene was distilled off under reduced pressure, and the resulting mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent. 110 parts of the surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran by stirring, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added thereto, followed by stirring for 5 hours at 50° C. Thereafter, the solid content was filtered off by reduced pressure filtration and dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin added thereto. 100 parts of a solution of 60 parts of alizarin-added zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, product name: Sumidur 3175, manufactured by Sumika Covestro Urethane Co., Ltd.), and 15 parts of butyral resin (product name: S-Lec BM-1, manufactured by Sekisui Chemical Co., Ltd.) dissolved in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone, and the mixture was dispersed for 2 hours in a sand mill using glass beads of 1 mm diameter to obtain a dispersion. 0.005 parts of dioctyltin dilaurate as a catalyst and 4 parts of silicone resin particles (product name: Tospearl 145, manufactured by Momentive Performance Materials Co., Ltd.) were added to the dispersion to obtain a coating liquid for forming an undercoat layer. The coating liquid for forming an undercoat layer was applied to the outer peripheral surface of a conductive substrate by a dip coating method, and the coating liquid was dried and cured at 170°C for 40 minutes to form an undercoat layer with an average thickness of 24 μm.

[0266] - Formation of charge generation layer - A mixture of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using Cukα characteristic X-rays) as a charge generating material, 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature (25°C±3°C) to form a charge generating layer with an average thickness of 0.18 μm.

[0267] - Formation of charge transport layer - 45 parts of a benzidine compound represented by the following formula (CTM1) as a charge transport material, 49.5 parts of resin 1 (polyester resin 1 (PE1)) as binder resins, and 5.5 parts of resin 2 (polycarbonate resin 1 (PC1)) were dissolved in 350 parts of toluene and 150 parts of tetrahydrofuran, and the mixture was treated five times with a high-pressure homogenizer to prepare a coating solution for the charge transport layer. The obtained coating liquid was applied onto the charge generating layer by dip coating, and heated at 130° C. for 45 minutes to form a charge transport layer having a thickness of 31 μm.

[0268] [ka]

[0269] [Electrophotographic photoreceptors (P2) to (P15), (CP1) to (CP4)] In forming the charge transport layer, the binder resins were of the types shown in Table 1, and electrophotographic photoreceptors were produced with the same specifications as the electrophotographic photoreceptor (P1), except that the amount ratio (based on mass) was changed.

[0270] <Preparation of Image Forming Apparatus> Each electrophotographic photoreceptor obtained as described above was attached to Apeos C2060 manufactured by FUJIFILM Business Innovation Co., Ltd. to obtain an image forming apparatus of each example. In the following evaluations, in the charging device of each example of the image forming apparatus, only a DC voltage was applied to the charging member from the voltage application unit, and the voltage applied from the voltage application unit to the charging member (also referred to as the "applied voltage") was -600 V.

[0271] <Wear resistance evaluation> First, the thickness of the photosensitive layer is measured and the measured value is designated as L1. Using the image forming apparatus of each example, 10,000 sheets of random character chart with 5% image density are continuously printed in an environment of 20°C temperature / 40% RH, and then the photoconductor is removed and the thickness of the photosensitive layer is measured again, and the measured value is designated as L2.Then, the absolute value of ΔL, which is the difference between L1 and L2, is calculated. The thickness of the coating was measured using an eddy current coating thickness meter. The evaluation criteria were as follows: A: ΔL is 2.0 μm or less B: ΔL is more than 2.0 μm and less than 5.0 μm C: ΔL exceeds 5.0 μm

[0272] <Evaluation of abnormal discharge> Using the image forming apparatus of each example, 5,000 A4 sheets were continuously printed using a random character chart with an image density of 5% in a high temperature and high humidity environment of 28°C and 85% RH. After that, a 20% halftone image was output, and the number of minute color lines on the image was counted and abnormal discharge was evaluated according to the following criteria. The fewer the number of minute color lines on the image, the less abnormal discharge there was. A: Not occurred B: 1 to 5 occurrences C: 6 or more occur

[0273] <Evaluation of cleaning ability> Using the image forming apparatus of each example, 10,000 sheets of random charts with an image density of 1% were output, and then one A3 image with an image density of 100% was output. Immediately after outputting the A3 image, streaks caused by residues remaining on the photoreceptor surface in the modified apparatus were observed, the number of streaks was counted, and the cleaning ability was evaluated according to the following criteria. A: No streaks B: 5 or less streaks D: Numerous streaks (6 or more) appear on the entire surface

[0274] [Table 1]

[0275] As shown in the table, it was found that the electrophotographic photoreceptors of Examples were superior in abrasion resistance, suppression of local abnormal discharge phenomenon, and cleaning ability, as compared with the electrophotographic photoreceptors of Comparative Examples.

[0276] The present embodiment includes the following aspects. (((1))) has an outermost layer containing a charge transport material and a binder resin, The binder resin has an elastic deformation rate X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is lower than 5% to 12% B Polycarbonate resin P having B and an electrophotographic photoreceptor comprising: (((2))) The polyester resin P A and the polycarbonate resin P B Content ratio of polyester resin P A : Polycarbonate resin P B ) is 7:3 to 3:7 on a mass basis. (((3))) The polyester resin P A and the polycarbonate resin P B Content ratio of polyester resin P A : Polycarbonate resin P B ) is 7:3 to 5:5 on a mass basis. (((4))) The polyester resin P A The electrophotographic photoreceptor according to any one of (((1))) to (((3))), comprising a polyester resin having a dicarboxylic acid unit (A) represented by the formula (A) described below and a diol unit (B) represented by the formula (B). (((5))) The polycarbonate resin P B The electrophotographic photoreceptor according to any one of (((1))) to (((4))), which contains a polycarbonate resin having a structural unit represented by the formula (PCA) described below and a structural unit represented by the formula (PCB) below.

[0277] (((6))) An electrophotographic photoreceptor according to any one of (((1))) to (((5))), A process cartridge that is detachably attached to an image forming apparatus. (((7))) An electrophotographic photoreceptor according to any one of (((1))) to (((5))); a charging device that comes into direct contact with the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor by applying only a DC voltage; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: (((8))) the charging device includes a charging member that charges a surface of the electrophotographic photoreceptor, and a DC voltage application unit that applies only a DC voltage to the charging member, The image forming apparatus according to (((7))), wherein the voltage applied from the DC voltage application section to the charging member is −700 V or more and −300 V or less.

[0278] According to the invention of (((1))), (((4))), or (((5))), a charge transport material and a binder resin are contained in an outermost layer, and the binder resin has an elastic deformation ratio X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is less than 5% lower or more than 12% lower than B Polycarbonate resin P having B In comparison with the case where the toner particles contain the above-mentioned, an electrophotographic photoreceptor is provided which is superior in abrasion resistance and can suppress abnormal discharge even when charged with a DC voltage alone. According to the invention related to (((2))) or (((3))), polyester resin P A : Polycarbonate resin P B However, compared with a case where the ratio does not satisfy 7:3 to 3:7 on a mass basis, an electrophotographic photoreceptor is provided which is superior in abrasion resistance and can suppress abnormal discharge even when charged only by a DC voltage. According to the invention of (((6))), (((7))), or (((8))), a charge transport material and a binder resin are contained in an outermost layer, and the binder resin has an elastic deformation ratio X A Polyester resin P with 53.0% or more A and the polyester resin P A Elastic deformation rate X A Elastic deformation rate X is less than 5% lower or more than 12% lower than B Polycarbonate resin P having Band a process cartridge or an image forming apparatus including an electrophotographic photosensitive member which has superior wear resistance and can suppress abnormal discharge even when charged by DC voltage alone, compared with a case in which the electrophotographic photosensitive member includes the above-mentioned. [Explanation of symbols]

[0279] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0280] 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming apparatus, 120 image forming apparatus, 131 cleaning blade, 132 fibrous member (roll-shaped), 133 fibrous member (flat brush-shaped), 300 process cartridge

Claims

1. a charge transport material and a binder resin; The binder resin has an elastic deformation rate X Ａ Polyester resin P having a content of 53.0% or more Ａ and the polyester resin P Ａ Elastic deformation rate X Ａ The elastic deformation rate X is lower in the range of 5% to 12%. Ｂ Polycarbonate resin P having Ｂ and an electrophotographic photoreceptor comprising:

2. The polyester resin P Ａ and the polycarbonate resin P Ｂ The content ratio of polyester resin P Ａ : Polycarbonate resin P Ｂ 2. The electrophotographic photoreceptor according to claim 1, wherein the ratio of the polymer to the polymerizable compound is from 7:3 to 3:7 on a weight basis.

3. The polyester resin P Ａ and the polycarbonate resin P Ｂ The content ratio of polyester resin P Ａ : Polycarbonate resin P Ｂ 3. The electrophotographic photoreceptor according to claim 2, wherein the ratio of the polymer to the polymerizable compound is from 7:3 to 5:5 on a mass basis.

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

5. The polycarbonate resin P Ｂ The electrophotographic photoreceptor according to claim 1 , wherein the polycarbonate resin has a structural unit represented by the following formula (PCA) and a structural unit represented by the following formula (PCB). 【Chemistry 2】 In the formula (PCA), R Ｐ１ and R Ｐ２ each independently represents a hydrogen atom, a halogen atom, an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 5 to 7 carbon atoms, or an aryl group having from 6 to 12 carbon atoms. In the formula (PCB), R Ｐ３ and R Ｐ４ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Ｐ１ represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5 is provided, A process cartridge that is detachably attached to an image forming apparatus.

7. The electrophotographic photoreceptor according to any one of claims 1 to 5, a charging device that comes into direct contact with the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor by applying only a DC voltage; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

8. the charging device includes a charging member that charges a surface of the electrophotographic photoreceptor, and a DC voltage application unit that applies only a DC voltage to the charging member, 8. The image forming apparatus according to claim 7, wherein the voltage applied from said DC voltage application section to said charging member is −700 V or more and −300 V or less.

Images