Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that has reduced the roughness of an outer peripheral surface.SOLUTION: An electrophotographic photoreceptor has a substrate and a photosensitive layer on the substrate. An outermost layer forming an outermost surface contains at least one selected from the group consisting of cyclic siloxane compounds represented by the specific general formulas (1)-(4) in a total amount of 0.0010 ppm or more.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] Patent Document 1 discloses an electrophotographic photoreceptor having a photosensitive layer and a protective layer provided in this order on a conductive substrate, the protective layer containing a charge transport agent having at least two hydroxy functional groups, a silicone oil having at least one type of hydroxy functional group, and at least one type of binder resin capable of forming a hydrogen bond with the hydroxy functional groups.

[0003] Patent Document 2 discloses an electrophotographic photoreceptor comprising a conductive support and a photosensitive layer disposed on the support, the photosensitive layer comprising a silicon compound-containing layer that contains a cyclic siloxane compound and / or a derivative thereof having a cyclic structure including a repeating unit represented by general formula (1).

[0004] Patent Document 3 discloses a method for forming a coating film for an electrophotographic photoreceptor, which comprises applying a coating material for an electrophotographic photoreceptor containing, as a volatile leveling agent, a silicone oil having a siloxane structure with a molecular weight of 1,000 or less, and then heating and drying the coating material to volatilize the leveling agent and form a coating film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-239887 [Patent Document 2] Patent No. 4322468 [Patent Document 3] Patent No. 3015074 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, when the surface roughness of the outer peripheral surface of an electrophotographic photosensitive member increases, the cleaning performance of the electrophotographic photosensitive member decreases, and defects may occur in an image formed on a recording medium due to the influence of toner, etc. remaining on the outer peripheral surface.

[0007] Therefore, an object of the present disclosure is to provide an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor containing only 0.0010 ppm or more of "KP340" manufactured by Shin-Etsu Chemical Co., Ltd. as a silicone oil in the outermost layer, and a process cartridge and an image forming apparatus each including the electrophotographic photoreceptor. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects. <1> A substrate; A photosensitive layer on the substrate, An electrophotographic photoreceptor, wherein an outermost layer constituting the outermost surface contains at least one cyclic siloxane compound selected from the group consisting of cyclic siloxane compounds represented by the following general formulas (1), (2), (3) and (4) in a total amount of 0.0010 ppm or more: [ka] (In the above general formulas (1), (2), (3) and (4), R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46each independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent. 11 , Z 12 , Z 21 , Z 22 , Z 23 , Z 31 , Z 32 , Z 33 , Z 34 , Z 41 , Z 42 , Z 43 , Z 44 , and Z 45 are each independently -Y 12 -X 12 X represents a group represented by the formula: 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42 Y each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, an alicyclic epoxy group, an amino group, a hydroxyl group, and a glycidyl group. 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 each independently represents a divalent organic linking group. <2> The outermost layer contains a cyclic siloxane compound represented by the general formula (2) in a total amount of 0.0010 ppm or more. <1> The electrophotographic photoreceptor according to claim 1. <3> In the cyclic siloxane compound represented by the general formula (2), 21 , Z 22 , and Z 23 One or three of the following are -Y 12 -X 12 is a group represented by <2> The electrophotographic photoreceptor according to claim 1. <4> In the cyclic siloxane compound represented by the general formula (2),22 Ga-Y 12 -X 12 The Z 21 and Z 23 is a hydrogen atom or a monovalent alkyl group; <3> The electrophotographic photoreceptor according to claim 1. <5> In the general formulas (1), (2), (3) and (4), the X 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42 each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, and an amino group; <1> The electrophotographic photoreceptor according to claim 1. <6> In the general formulas (1), (2), (3) and (4), the Y 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 Each independently represents -(CH2) n - represents a divalent organic linking group (where n = 1 or more and 8 or less), <1> The electrophotographic photoreceptor according to claim 1. <7> In the general formulas (1), (2), (3) and (4), 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46each independently represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms which may have a substituent; <1> The electrophotographic photoreceptor according to claim 1. <8> The cyclic siloxane compound is contained in a total amount of 0.005 ppm or more and 20 ppm or less. <1> The electrophotographic photoreceptor according to claim 1. <9> The cyclic siloxane compound is contained in a total amount of 0.1 ppm or more and 15 ppm or less. <8> The electrophotographic photoreceptor according to claim 1. <10> The outer peripheral surface of the outermost layer has a surface roughness Ra of 15 nm or less. <1> The electrophotographic photoreceptor according to claim 1. <11> The surface roughness Ra of the outer peripheral surface of the outermost layer is 1 nm or more and 10 nm or less. <10> The electrophotographic photoreceptor according to claim 1. <12> <1> The electrophotographic photoreceptor according to claim 1, A process cartridge that is detachably attached to an image forming apparatus. <13> <1> and an electrophotographic photoreceptor according to the above item (1); a charging means for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing unit 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 means for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: Effect of the Invention

[0009] <1> , <6> or <7> According to the present invention, there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, compared to an electrophotographic photoreceptor containing only 0.0010 ppm or more of "KP340" manufactured by Shin-Etsu Chemical Co., Ltd. as silicone oil in the outermost layer. <2> According to the present invention, there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor containing less than 0.0010 ppm in total of cyclic siloxane compounds represented by general formula (2) in the outermost layer. <3> or <4> According to the present invention, Z in the cyclic siloxane compound represented by general formula (2) 21 , Z 22 , and Z 23 0 or 2 of the characters are -Y 12 -X 12 In this way, an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface is provided, as compared with an electrophotographic photoreceptor having a group represented by the formula: <5> According to the present invention, the cyclic siloxane compound is represented by the general formula (2) 21 , vX 22 As compared with an electrophotographic photoreceptor containing only a cyclic siloxane compound in which the cyclic epoxy group is an alicyclic epoxy group, an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface is provided. <8> or <9> According to the invention, there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor having a total content of cyclic siloxane compounds of less than 0.005 ppm. <10> or <11> According to the invention, there is provided an electrophotographic photoreceptor in which deterioration in cleaning performance is suppressed, as compared with an electrophotographic photoreceptor in which the outer peripheral surface of the outermost layer has a surface roughness Ra of more than 15 nm. <12> or <13> According to the invention, there is provided a process cartridge and an image forming apparatus equipped with an electrophotographic photoreceptor in which deterioration in cleaning performance is suppressed compared to a case in which an electrophotographic photoreceptor containing only "KP340" manufactured by Shin-Etsu Chemical Co., Ltd. at 0.0010 ppm or more as silicone oil in the outermost layer. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of the electrophotographic photoreceptor of the present embodiment. [Diagram 2] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Diagram 3] 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 numerical ranges described in this specification, 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 another stepwise manner. In addition, in the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0013] In this specification, each component may contain multiple corresponding substances. In this specification, when referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0014] [Electrophotographic photoreceptor] The electrophotographic photoreceptor (hereinafter also simply referred to as "photoreceptor") according to an embodiment of the present disclosure has a substrate and a photosensitive layer on the substrate. The outermost layer constituting the outermost surface contains at least one selected from the group consisting of cyclic siloxane compounds represented by the following general formulas (1), (2), (3) and (4) in a total amount of 0.0010 ppm or more.

[0015] [ka] (In the above general formulas (1), (2), (3) and (4), R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 Each of Z independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent. 11 , Z 12 , Z 21 , Z 22 , Z 23 , Z 31 , Z 32 , Z 33 , Z 34 , Z 41 , Z 42 , Z 43 , Z 44 , and Z 45 are each independently -Y 12 -X 12 X represents a group represented by the formula: 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42 Y each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, an alicyclic epoxy group, an amino group, a hydroxyl group, and a glycidyl group. 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 each independently represents a divalent organic linking group.

[0016] The photoreceptor according to the embodiment of the present disclosure, which contains the cyclic siloxane compound, has reduced roughness on the outer peripheral surface. The reason for this effect is presumed to be as follows.

[0017] When the outer peripheral surface of the photoreceptor becomes rough (i.e., the surface roughness increases), the cleaning performance of the photoreceptor decreases, and defects may occur in the image formed on the recording medium due to the influence of toner, etc. remaining on the outer peripheral surface. Note that the surface roughness of the outer peripheral surface of the photoreceptor may be affected by hardening and shrinkage that occurs on the surface of the coating film during the drying process after coating the coating liquid for forming the outermost layer when forming the outermost layer, for example, and the surface of the photoreceptor may become rough.

[0018] In contrast, the photoreceptor according to the embodiment of the present disclosure contains at least one selected from the group consisting of cyclic siloxane compounds represented by the general formulas (1), (2), (3) and (4) in the amount described above. By containing the cyclic siloxane compound represented by the general formula, stress relaxation due to the cyclic siloxane skeleton is realized, curing shrinkage of the outermost layer is alleviated, and roughness on the outer peripheral surface is reduced. As a result, deterioration of cleaning performance in the photoreceptor is suppressed, and occurrence of image defects due to the influence of toner remaining on the outer peripheral surface is suppressed.

[0019] -Cyclic siloxane compounds- Here, the cyclic siloxane compound contained in the outermost layer of the photoreceptor according to the embodiment of the present disclosure will be described. The cyclic siloxane compound has a structure represented by the above-mentioned general formula (1), (2), (3) or (4).

[0020] In the general formulas (1), (2), (3) and (4), R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46R each independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent. 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 From the viewpoint of reducing the roughness on the outer peripheral surface of the photoreceptor, it is preferable that each of them independently represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms which may have a substituent.

[0021] R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 The monovalent alkyl group represented by the following formula may have a substituent.

[0022] Examples of the unsubstituted alkyl group include a linear alkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), a branched alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms), and a cyclic alkyl group having 3 to 20 carbon atoms (preferably 3 to 10 carbon atoms).

[0023] Examples of the linear alkyl group having 1 to 20 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, 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.

[0024] Examples of the branched alkyl group having 3 to 20 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, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group.

[0025] Examples of the cyclic alkyl group having 3 to 20 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 groups formed by linking these monocyclic alkyl groups.

[0026] Among the above, as the unsubstituted alkyl group, a straight-chain alkyl group such as a methyl group or an ethyl group is preferable.

[0027] Substituents in the alkyl group include an alkoxy group, a hydroxy group, a carboxy group, a nitro group, and a halogen atom (such as a fluorine atom, a bromine atom, or an iodine atom).

[0028] In the general formulas (1), (2), (3) and (4), Z 11 , Z 12 , Z 21 , Z22 , Z 23 , Z 31 , Z 32 , Z 33 , Z 34 , Z 41 , Z 42 , Z 43 , Z 44 , and Z 45 are each independently -Y 12 -X 12 Z represents a group represented by the formula: 11 , Z 12 , Z 21 , Z 22 , Z 23 , Z 31 , Z 32 , Z 33 , Z 34 , Z 41 , Z 42 , Z 43 , Z 44 , and Z 45 Preferred examples of the monovalent alkyl group which may have a substituent represented by the formula: 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 The substituents are the same as those of the monovalent alkyl group which may have a substituent and is represented by the following formula:

[0029] In the general formulas (1), (2), (3) and (4), X 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, an alicyclic epoxy group, an amino group, a hydroxyl group, and a glycidyl group.

[0030] The succinic anhydride group, the amino group, the hydroxyl group, and the glycidyl group each have the structure shown below: The (meth)acrylic group represents an acrylic group or a methacrylic group, each having the structure shown below. The alicyclic epoxy group is not limited as long as it is a monovalent group having an alicyclic structure and an epoxy group, and examples thereof include the following alicyclic epoxy group (1): In addition to the following alicyclic epoxy group (1), examples include alicyclic epoxy groups having an alicyclic structure in which the alicyclic structure portion has 3 to 20 carbon atoms, and the epoxy group may be located anywhere in the alicyclic structure. The monovalent groups shown below are linked at the "*" portion.

[0031] [ka]

[0032] X 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42 From the viewpoint of reducing the roughness on the outer peripheral surface of the photoreceptor, it is preferable that each of them independently is a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, and an amino group.

[0033] In the general formulas (1), (2), (3) and (4), Y 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42Each of Y independently represents a divalent organic linking group. The organic linking group refers to a divalent group containing carbon. An example of the divalent organic linking group is a divalent alkyl group which may have a substituent. 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 Preferred examples of the optionally substituted divalent alkyl group in the formula (I) include R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 Further, a group represented by the formula (I) is a monovalent alkyl group which may have a substituent and is represented by the formula (I) below, and which is divalent by removing one hydrogen atom from the monovalent alkyl group represented by the formula (I). 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 Each of the groups independently represents -(CH2) from the viewpoint of reducing the roughness of the outer peripheral surface of the photoconductor. n It is preferably a divalent organic linking group represented by the formula - (wherein n is preferably 1 or more and 8 or less, and more preferably 1 or more and 6 or less).

[0034] From the viewpoint of reducing the roughness on the outer peripheral surface of the photoreceptor, the cyclic siloxane compound contained in the outermost layer is preferably a cyclic siloxane compound represented by general formula (2), and it is preferable that the cyclic siloxane compound represented by general formula (2) is contained in a total amount of 0.0010 ppm or more.

[0035] From the viewpoint of reducing the roughness of the outer peripheral surface of the photoreceptor, it is preferable that the cyclic siloxane compound represented by the general formula (2) has two or four functional groups, that is, Z 21 , Z 22 , and Z 23 One or three of the following are -Y 12 -X 12 Furthermore, it is preferable that the cyclic siloxane compound represented by the general formula (2) has two functional groups, that is, Z 22 -Y 12 -X 12 is a group represented by 21 and Z 23 It is more preferable that is a hydrogen atom or a monovalent alkyl group.

[0036] -Specific examples of cyclic siloxane compounds- Preferred specific examples of the cyclic siloxane compound include compounds No. 1 to No. 14 in the table below, in which R each independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent, and n is 1 or more and 6 or less.

[0037] [Table 1]

[0038] [ka]

[0039] The outermost layer contains at least one selected from the group consisting of cyclic siloxane compounds represented by general formulas (1), (2), (3) and (4) in a total amount of 0.0010 ppm or more. From the viewpoint of reducing the roughness of the outer peripheral surface of the photoreceptor, the outermost layer contains the cyclic siloxane compounds in a total amount of preferably 0.005 ppm or more and 20 ppm or less, more preferably 0.1 ppm or more and 15 ppm or less.

[0040] The surface roughness Ra (arithmetic mean surface roughness Ra) of the outer peripheral surface of the outermost layer is preferably 15 nm or less, more preferably 10 nm or less, and even more preferably 8 nm or less, from the viewpoint of suppressing deterioration of the cleaning performance of the photoreceptor. The lower limit of the surface roughness Ra may be 0 nm or more, or may be 1 nm or more.

[0041] The surface roughness Ra (arithmetic mean surface roughness Ra) is measured as follows. A part of the outermost layer to be measured is cut out with a cutter or the like to obtain a measurement sample. This measurement sample is measured using a stylus-type surface roughness measuring instrument (Surfcom 1400A: manufactured by Tokyo Seimitsu Co., Ltd., etc.). The measurement conditions are in accordance with JIS B0601-1994, with evaluation length Ln = 2.5 mm, reference length L = 0.8 mm, and cutoff value = 0.008 mm.

[0042] Next, the layer structure of the electrophotographic photoreceptor according to the present embodiment will be described with reference to the drawings.

[0043] In the drawings, the same or corresponding parts are given the same symbols and duplicate explanations are omitted. 1 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment. The photoreceptor 107A has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a charge generation layer 102 and a charge transport layer 103 are sequentially formed thereon. The photoreceptor 107A has an organic photoreceptor layer 105 whose functions are separated into the charge generation layer 102 and the charge transport layer 103. An intermediate layer may be provided between the conductive substrate 104 and the undercoat layer 101.

[0044] In photoreceptor 107A, charge transport layer 103 constitutes the outermost layer. However, the present disclosure is not limited to this configuration, and the outermost layer in the photoreceptor may be, for example, a charge generation layer, or may be an integrated organic photoreceptor layer in which the charge generation layer and the charge transport layer are not functionally separated.

[0045] Hereinafter, each element constituting the electrophotographic photoreceptor will be described, with the reference numerals sometimes omitted.

[0046] (charge transport layer) In photoreceptor 107A, charge transport layer 103 constitutes the outermost layer. Charge transport layer 103, which is the outermost layer, contains at least one selected from the group consisting of cyclic siloxane compounds represented by general formulas (1), (2), (3), and (4) in a total amount of 0.0010 ppm or more. The components other than the cyclic siloxane compound in the charge transport layer will be described below.

[0047] The charge transport layer according to the present embodiment contains, for example, a binder resin and a charge transport material. The charge transport layer may further contain inorganic particles, fluorine-containing resin particles, well-known additives, etc. The charge transport layer is provided on a charge generation layer described later.

[0048] ·Charge transport material Examples of charge transport materials include electron transport 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 transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds.

[0049] The charge transport material preferably contains at least one of a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2).

[0050] [ka]

[0051] 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 , R T5 , 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.

[0052] [ka]

[0053] 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 RT16 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.

[0054] 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 preferred.

[0055] The charge transport material preferably contains a charge transport material having a molecular weight of 850 or less, more preferably contains a charge transport material having a molecular weight of 50 to 600, and even more preferably contains a charge transport material having a molecular weight of 90 to 550.

[0056] Specific examples of the charge transport material are given below, but the charge transport material according to this embodiment is not limited thereto.

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] For example, when the charge transport material contains two kinds of materials, that is, one kind selected from the triarylamine derivatives represented by structural formula (a-1) and one kind selected from the triarylamine derivatives represented by structural formula (a-2), the blending ratio of the two kinds is not particularly limited, but for example, the ratio (one kind selected from the triarylamine derivatives represented by structural formula (a-1) / one kind selected from the triarylamine derivatives represented by structural formula (a-2)) is preferably 10 / 1 or more and 1 / 10 or less, more preferably 5 / 1 or more and 1 / 5 or less, and even more preferably 2 / 1 or more and 1 / 2 or less.

[0062] In the charge transport layer according to this embodiment, the content of the charge transport material is preferably 10% by mass or more and 50% by mass or less, and may be 20% by mass or more and 40% by mass or less, or may be 25% by mass or more and 40% by mass or less, based on the total amount of the charge transport material and the binder resin in the charge transport layer.

[0063] ·Binding resin Specific examples of binder resins include polycarbonate resins (homopolymerized types of bisphenol A, bisphenol Z, bisphenol C, bisphenol TP, etc., or copolymerized types thereof), polyarylate resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers, polyvinyl acetate resins, styrene-butadiene copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, styrene-acrylic copolymers, ethylene-alkyd resins, poly-N-vinylcarbazole resins, polyvinyl butyral resins, polyphenylene ether resins, etc. The binder resins are used alone or in combination of two or more. The compounding ratio of the charge transport material to the binder resin is preferably from 10:1 to 1:5 by mass.

[0064] Among the above-mentioned binder resins, polycarbonate resins (homopolymer type of bisphenol A, bisphenol Z, bisphenol C, bisphenol TP, etc., or copolymer type thereof) are preferred. The polycarbonate resins may be used alone or in combination of two or more. From the same point of view, among polycarbonate resins, it is more preferred to include a homopolymer type polycarbonate resin of bisphenol Z.

[0065] The binder resin may have a viscosity average molecular weight of, for example, 50,000 or less. It may also have a viscosity average molecular weight of 45,000 or less, or 35,000 or less. The lower limit of the viscosity average molecular weight is preferably 20,000 or more in order to maintain the properties as a binder resin.

[0066] The viscosity average molecular weight of the binder resin is measured by the following single-point measurement method. First, the charge transport layer to be measured is exposed from the photoconductor to be measured, and then a part of the charge transport layer is scraped off to prepare a measurement sample. Next, the binder resin is extracted from the measurement sample. 1 g of the extracted binder resin is dissolved in 100 cm of methylene chloride. 3 The specific viscosity ηsp is measured using an Ubbelohde viscometer at a measurement environment of 25°C. Then, ηsp / c = [η] + 0.45 [η] 2 c (where c is the concentration (g / cm 3 ) to obtain the intrinsic viscosity [η] (cm 3 / g) and the formula given by H. Schnell, [η] = 1.23 × 10 -4 Mv 0.83 The viscosity average molecular weight Mv is calculated from the following equation.

[0067] ·Inorganic particles Examples of inorganic particles include silica particles, alumina particles, titanium oxide particles, calcium carbonate particles, magnesium carbonate particles, tricalcium phosphate particles, and cerium oxide particles. The inorganic particles may be used alone or in combination of two or more kinds. Among the above, the charge transport layer according to the present embodiment preferably contains silica particles.

[0068] The silica particles preferably account for 90% by mass or more and 100% by mass or less, more preferably 98% by mass or more and 100% by mass or less, and even more preferably 100% by mass, based on the total amount of the inorganic particles.

[0069] The content of the inorganic particles is preferably 30% by mass or more and 70% by mass or less, more preferably 50% by mass or more and 70% by mass or less, and even more preferably 60% by mass or more and 70% by mass or less, based on the total solid content of the charge transport layer.

[0070] The silica particles may be either dry silica particles or wet silica particles. Examples of dry silica particles include combustion silica (fumed silica) obtained by burning a silane compound, and deflagration silica obtained by explosively burning metallic silicon powder. Examples of wet silica particles include wet silica particles obtained by a neutralization reaction between sodium silicate and a mineral acid (precipitation method silica synthesized and agglomerated under alkaline conditions, gel method silica particles synthesized and agglomerated under acidic conditions), colloidal silica particles (silica sol particles) obtained by making acidic silicic acid alkaline and polymerizing it, and sol-gel method silica particles obtained by hydrolysis of an organic silane compound (e.g., alkoxysilane). Among these, from the viewpoint of suppressing the generation of residual potential, it is preferable to use combustion method silica particles having a low silanol group content on the surface and a low void structure.

[0071] The volume average particle diameter of the silica particles is preferably, for example, 20 nm or more and 200 nm or less. The lower limit of the volume average particle diameter of the silica particles may be 40 nm or more, or 50 nm or more. The lower limit of the volume average particle diameter of the silica particles may be 150 nm or less, 120 nm or less, or 110 nm or less.

[0072] The volume average particle size of the silica particles is measured by separating the silica particles from the layer, observing 100 primary particles of the silica particles with a scanning electron microscope (SEM) at a magnification of 40,000 times, measuring the longest and shortest diameters of each particle by image analysis of the primary particles, and measuring the sphere-equivalent diameter from the intermediate value. The 50% diameter (D50v) of the cumulative frequency of the obtained sphere-equivalent diameters is calculated and measured as the volume average particle size of the silica particles.

[0073] The silica particles are preferably surface-treated with a hydrophobizing agent, which reduces the number of silanol groups on the surfaces of the silica particles and makes it easier to suppress the generation of residual potential. Examples of the hydrophobic treatment agent include well-known silane compounds such as chlorosilane, alkoxysilane, and silazane. Among these, the hydrophobizing agent is preferably a silane compound having a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group, from the viewpoint of easily suppressing the generation of residual potential. In other words, it is preferable that the surface of the silica particle has a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group. Examples of silane compounds having a trimethylsilyl group include trimethylchlorosilane, trimethylmethoxysilane, and 1,1,1,3,3,3-hexamethyldisilazane. Examples of silane compounds having a decylsilyl group include decyltrichlorosilane, decyldimethylchlorosilane, and decyltrimethoxysilane. Examples of the silane compound having a phenyl group include triphenylmethoxysilane and triphenylchlorosilane.

[0074] The condensation rate of the hydrophobized silica particles (the ratio of Si-O-Si in the SiO4- bonds in the silica particles: hereinafter also referred to as the "condensation rate of the hydrophobizing agent") is, for example, 90% or more, preferably 91% or more, and more preferably 95% or more, based on the silanol groups on the surface of the silica particles. When the condensation rate of the hydrophobizing agent is within the above range, the silanol groups of the silica particles are further reduced, and the generation of residual potential is easily suppressed.

[0075] The condensation rate of the hydrophobic treatment agent indicates the ratio of condensed silicon to the total bondable sites of silicon in the condensed portion detected by NMR, and is measured as follows. First, the silica particles are separated from the layer. The separated silica particles are subjected to Si CP / MAS NMR analysis using a Bruker AVANCEIII 400 to obtain the peak area according to the number of SiO substitutions, and the values ​​of 2-substitution (Si(OH)2(0-Si)2-), 3-substitution (Si(OH)(0-Si)3-), and 4-substitution (Si(0-Si)4-) are respectively designated as Q2, Q3, and Q4, and the condensation rate of the hydrophobic treatment agent is calculated by the formula: (Q2×2+Q3×3+Q4×4) / 4×(Q2+Q3+Q4).

[0076] The volume resistivity of silica particles is, for example, 10 11 Ωcm or more is good, 10 12 Ωcm or more is preferable, and 10 13 More preferably, it is Ωcm or more. When the volume resistivity of the silica particles is within the above range, the deterioration of the electrical properties is suppressed.

[0077] The volume resistivity of the silica particles is measured as follows, where the measurement environment is a temperature of 20° C. and a humidity of 50% RH. First, the silica particles are separated from the layer. Then, 2 On the surface of the circular jig on which the electrode plate is arranged, the separated silica particles to be measured are placed to a thickness of about 1 mm to 3 mm to form a silica particle layer. 2An electrode plate is placed on top of the silica particle layer and the silica particle layer is sandwiched between them. In order to eliminate gaps between the silica particles, a load of 4 kg is placed on the electrode plate placed on the silica particle layer, and then the thickness (cm) of the silica particle layer is measured. An electrometer and a high-voltage power supply generator are connected to both electrodes above and below the silica particle layer. A high voltage is applied to both electrodes so that the electric field becomes a predetermined value, and the current value (A) that flows at this time is read to calculate the volume resistivity (Ωcm) of the silica particles. The formula for calculating the volume resistivity (Ωcm) of silica particles is as shown below. In the formula, ρ is the volume resistivity (Ωcm) of the silica particles, E is the applied voltage (V), I is the current value (A), I0 is the current value (A) at an applied voltage of 0 V, and L is the thickness (cm) of the silica particle layer. In this evaluation, the volume resistivity when the applied voltage was 1000 V was used. Formula: ρ=E×20 / (I-I0) / L

[0078] Fluorine-containing resin particles As the fluorine-containing resin particles, it is preferable to select one or more kinds from, for example, tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin, and copolymer particles thereof. Among these, tetrafluoroethylene resin particles and vinylidene fluoride resin particles are particularly preferable as the fluorine-containing resin particles.

[0079] The primary particle size of the fluorine-containing resin particles is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. The primary particles are obtained by obtaining a sample piece from the photosensitive layer (charge transport layer), observing the sample piece with a SEM (scanning electron microscope) at a magnification of, for example, 5000 times or more, measuring the maximum diameter of the fluororesin particles in the primary particle state, and taking the average value for 50 particles. The SEM used is a JEOL JSM-6700F, and secondary electron images are observed at an accelerating voltage of 5 kV.

[0080] Commercially available fluororesin particles include, for example, the Lubron (registered trademark) series (manufactured by Daikin Industries, Ltd.), the Teflon (registered trademark) series (manufactured by DuPont), and the Dyneon (registered trademark) series (manufactured by Sumitomo 3M).

[0081] The content of the fluorine-containing resin particles is preferably from 1 to 30% by mass, more preferably from 3 to 20% by mass, and even more preferably from 5 to 15% by mass, based on the total solid content of the photosensitive layer (charge transport layer).

[0082] The charge transport layer according to this embodiment may further contain a fluorine-containing dispersant in addition to the fluorine-containing resin particles. Next, the fluorine-containing dispersant will be described. The fluorine-containing dispersant may be a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group (hereinafter also referred to as a "fluorinated alkyl group-containing polymer").

[0083] Specific examples of the fluorine-containing dispersant include homopolymers of (meth)acrylates having a fluoroalkyl group, random or block copolymers of (meth)acrylates having a fluoroalkyl group and monomers not having fluorine atoms, etc. Note that (meth)acrylate refers to both acrylate and methacrylate. Examples of the (meth)acrylate having a fluorinated alkyl group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropyl (meth)acrylate. Examples of monomers not having a fluorine atom include (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, and ethyl carbitol (meth). p)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethyl o-phenylphenol (meth)acrylate, o-phenylphenol glycidyl ether (meth)acrylate.

[0084] Other specific examples of the fluorine-containing dispersant include block or branched polymers disclosed in U.S. Patent No. 5,637,142 and Japanese Patent No. 4,251,662. Further specific examples of the fluorine-containing dispersant include fluorine-based surfactants.

[0085] Among these, as the fluorine-containing dispersant, a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) is preferred, and a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) is more preferred.

[0086] Hereinafter, a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) will be described.

[0087] [ka]

[0088] In the general formulas (FA) and (FB), R F1 , R F2 , R F3 and R F4 each independently represents a hydrogen atom or an alkyl group. X F1 represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond. Y F1 is an alkylene chain, a halogen-substituted alkylene chain, -(C fx H 2fx-1 (OH))- or a single bond. Q F1 represents -O- or -NH-. Each of fl, fm and fn independently represents an integer of 1 or more. fp, fq, fr and fs each independently represent an integer of 0 or 1 or more. ft represents an integer between 1 and 7. fx represents an integer of 1 or greater.

[0089] In the general formulas (FA) and (FB), R F1 , R F2 , R F3 and R F4 The group represented by the formula (I) is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, or the like, more preferably a hydrogen atom or a methyl group, and even more preferably a methyl group.

[0090] In the general formulas (FA) and (FB), X F1 and Y F1 The alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) represented by the formula (I) is preferably a linear or branched alkylene chain having 1 to 10 carbon atoms. Y F1 Represents -(C fx H 2fx-1 It is preferable that fx in (OH)- represents an integer of 1 or more and 10 or less. It is preferable that fp, fq, fr and fs each independently represent 0 or an integer of 1 or more and 10 or less. It is preferable that fn is, for example, 1 or more and 60 or less.

[0091] Here, in the fluorine-containing dispersant, the ratio of the structural unit represented by general formula (FA) to the structural unit represented by general formula (FB), i.e., fl:fm, is preferably in the range of 1:9 to 9:1, and more preferably in the range of 3:7 to 7:3.

[0092] The fluorine-containing dispersant may further have a structural unit represented by the following general formula (FC) in addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB). The content ratio of the structural unit represented by the general formula (FC) is preferably in the range of 10:0 to 7:3, more preferably in the range of 9:1 to 7:3, in terms of the ratio (fl+fm:fz) to the total of the structural units represented by the general formulas (FA) and (FB), i.e., fl+fm.

[0093] [ka]

[0094] In the general formula (FC), R F5 , and R F6 each independently represents a hydrogen atom or an alkyl group, and fz represents an integer of 1 or greater.

[0095] In the general formula (FC), R F5 , and R F6 The group represented by the formula (I) is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, or the like, more preferably a hydrogen atom or a methyl group, and even more preferably a methyl group.

[0096] Commercially available fluorine-containing dispersants include, for example, GF300, GF400 (manufactured by Toagosei Co., Ltd.), Surflon (registered trademark) series (manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent series (manufactured by Neos Corporation), PF series (manufactured by Kitamura Chemical Co., Ltd.), Megafac (registered trademark) series (manufactured by DIC), and FC series (manufactured by 3M).

[0097] The weight average molecular weight of the fluorine-containing dispersant is, for example, preferably 2,000 or more and 250,000 or less, more preferably 3,000 or more and 150,000 or less, and even more preferably 50,000 or more and 100,000 or less. The weight average molecular weight of a fluorine-containing dispersant is a value measured by gel permeation chromatography (GPC). For example, molecular weight measurement by GPC is performed using a Tosoh GPC HLC-8120 as a measuring device, a Tosoh TSKgel GMHHR-M + TSKgel GMHHR-M (7.8mm I.D. 30cm) column, and a chloroform solvent, and the molecular weight is calculated from the measurement results using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

[0098] The content of the fluoroalkyl group-containing polymer is, for example, preferably from 0.5% by mass to 10% by mass, more preferably from 1% by mass to 7% by mass, based on the mass of the fluorine-containing resin particles. The fluoroalkyl group-containing polymers may be used alone or in combination of two or more kinds.

[0099] Formation of charge transport layer 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.

[0100] 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.

[0101] 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.

[0102] When particles (e.g., silica particles or fluororesin particles) are dispersed in the coating liquid for forming the charge transport layer, the dispersion method may be, for example, a media disperser such as a ball mill, a vibration ball mill, an attritor, a sand mill, or a horizontal sand mill, or a media-less disperser such as an agitator, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer. 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 is dispersed by penetrating a fine flow path under high pressure.

[0103] (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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the material 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.

[0111] (subbing layer) The undercoat layer may be, for example, a layer containing inorganic particles and a binder resin, or may be a layer made of a metal oxide.

[0112] Layer containing inorganic particles and resin particles The inorganic particles in the layer containing inorganic particles and resin particles have a 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.

[0113] 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).

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] Here, when the undercoat layer is a layer containing inorganic particles and resin particles, 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.

[0122] 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; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone. 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] When the undercoat layer is a layer containing inorganic particles and resin particles, 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, oxide 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0136] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0137] When the undercoat layer is a layer containing inorganic particles and resin particles, 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.

[0138] When the undercoat layer is a layer containing inorganic particles and resin particles, 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 an undercoat layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] When the undercoat layer is a layer containing inorganic particles and resin particles, the thickness of the undercoat layer is set, for example, preferably 15 μm or more, more preferably in the range of 20 μm or more and 50 μm or less.

[0143] -Metal oxide layer The undercoat layer, which is a layer made of a metal oxide, refers to a layer of a metal oxide (for example, a CVD film of a metal oxide, a vapor deposition film of a metal oxide, a sputtered film of a metal oxide, etc.), and does not include aggregates or aggregates of metal oxide particles. As the undercoat layer made of a metal oxide layer, a metal oxide layer made of a metal oxide containing a Group 13 element and oxygen is preferred because it has excellent mechanical strength, light transmittance, and electrical conductivity. Examples of metal oxides containing a Group 13 element and oxygen include metal oxides such as gallium oxide, aluminum oxide, indium oxide, and boron oxide, and mixed crystals of these. Among these, as the metal oxide containing a Group 13 element and oxygen, gallium oxide is particularly preferred from the viewpoints of excellent mechanical strength and light transmittance, particularly having n-type conductivity, and excellent controllability of the conductivity. In other words, the layer made of a metal oxide is preferably a metal oxide layer containing gallium and oxygen. The undercoat layer made of a metal oxide layer is preferably a layer made of a metal oxide containing a Group 13 element (preferably gallium) and oxygen, but may be a layer containing hydrogen and carbon atoms as necessary.

[0144] The undercoat layer made of a metal oxide layer may further include a layer containing zinc (Zn). The undercoat layer made of a metal oxide layer may contain other elements to control the conductivity type. In order to control the conductivity type, the undercoat layer made of a metal oxide layer may contain one or more elements selected from C, Si, Ge, and Sn in the case of n-type, and may contain one or more elements selected from N, Be, Mg, Ca, and Sr in the case of p-type. In particular, it is preferable that the undercoat layer made of a metal oxide layer contains a Group 13 element, oxygen, and hydrogen, and that the sum of the elemental composition ratios of the Group 13 element, oxygen, and hydrogen to all elements constituting the undercoat layer made of a metal oxide layer is 90 atomic % or more.

[0145] The undercoat layer made of a metal oxide layer can be formed by known vapor phase deposition methods such as plasma CVD (Chemical Vapor Deposition), metalorganic vapor phase epitaxy, molecular beam epitaxy, vapor deposition, and sputtering.

[0146] The thickness of the undercoat layer made of a metal oxide layer is preferably from 0.1 μm to 10 μm, more preferably from 0.2 μm to 8.0 μm, and even more preferably from 0.5 μm to 5.0 μm.

[0147] (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.

[0148] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0149] 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.

[0150] 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.

[0151] (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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] The charge generating layer may contain other well-known additives.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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 0.15 μm or more and 2.0 μm or less.

[0165] [Image forming device (and process cartridge)] The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging unit for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing unit 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 unit for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

[0166] 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 means for fixing a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type for directly transferring a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type for primarily transferring a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member, and then secondarily transferring 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 means for cleaning the surface of an electrophotographic photosensitive member before charging after the transfer of a toner image; an apparatus provided with a discharging means for irradiating the surface of an electrophotographic photosensitive member with discharging light to discharge the surface 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.

[0167] In the case of an intermediate transfer type device, the transfer means has, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0168] 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).

[0169] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photoreceptor 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 the electrophotographic photoreceptor according to the present embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may include at least one selected from the group consisting of a charging means, an electrostatic latent image forming means, a developing means, and a transfer means.

[0170] 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.

[0171] FIG. 2 is a schematic diagram showing an example of the image forming apparatus according to the present embodiment. As shown in FIG. 2, 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 means), 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 means. In the image forming apparatus 100, the control device 60 (an example of a control means) is a device that controls the operation of each device and each member within the image forming apparatus 100, and is arranged so as to be connected to each device and each member.

[0172] 2 supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging means), a developing device 11 (an example of a developing means), and a cleaning device 13 (an example of a cleaning means) 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.

[0173] FIG. 2 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.

[0174] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0175] -Charging device- As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also, a non-contact type roller charger, a scorotron charger or corotron charger that utilizes corona discharge, or other chargers known per se, can be used.

[0176] -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.

[0177] -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.

[0178] 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.

[0179] -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.

[0180] -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.

[0181] -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.

[0182] -Control device- The control device 60 is configured as a computer that controls the entire device and performs various calculations. Specifically, the control device 60 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores various programs, a RAM (Random Access Memory) that is used as a work area when the programs are executed, a non-volatile memory that stores various information, and an input / output interface (I / O). The CPU, ROM, RAM, non-volatile memory, and I / O are each connected via a bus. The I / O is connected to each part of the image forming device 100, such as the electrophotographic photosensitive member 7 (including the driving motor 30), the charging device 8, the exposure device 9, the developing device 11, and the transfer device 40.

[0183] The CPU executes programs (e.g., control programs for an image formation sequence, a recovery sequence, etc.) stored in, for example, a ROM or a non-volatile memory, and controls the operation of each part of the image forming apparatus 100. The RAM is used as a work memory. For example, the programs executed by the CPU and data necessary for the CPU's processing are stored in the ROM or non-volatile memory. The control programs and various data may be stored in other storage devices such as a storage unit, or may be acquired from outside via a communication unit.

[0184] Various drives may also be connected to the control device 60. Examples of the various drives include devices that read data from and write data to computer-readable portable recording media such as flexible disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and USB (Universal Serial Bus) memories. When various drives are provided, a control program may be recorded on a portable recording medium and read and executed by a corresponding drive.

[0185] FIG. 3 is a schematic diagram showing another example of the image forming apparatus according to the present embodiment. 3 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.

[0186] The image forming apparatus 100 according to the present embodiment is not limited to the above configuration, and may be, for example, provided around the electrophotographic photosensitive member 7, downstream of the transfer device 40 in the rotation direction of the electrophotographic photosensitive member 7 and upstream of the cleaning device 13 in the rotation direction of the electrophotographic photosensitive member, with a first static elimination device for aligning the polarity of residual toner to make it easier to remove with a cleaning brush, or may be provided downstream of the cleaning device 13 in the rotation direction of the electrophotographic photosensitive member and upstream of the charging device 8 in the rotation direction of the electrophotographic photosensitive member, with a second static elimination device for eliminating static electricity from the surface of the electrophotographic photosensitive member 7.

[0187] Furthermore, the image forming apparatus 100 according to this embodiment is not limited to the above configuration, and may have a well-known configuration, for example, a direct transfer type image forming apparatus in which a toner image formed on an electrophotographic photosensitive member 7 is directly transferred to a recording medium. EXAMPLES

[0188] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to the following examples. The materials, amounts used, ratios, processing procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present disclosure.

[0189] Example 1 - Formation of undercoat layer - Zinc oxide: (average particle size 70 nm: manufactured by Teika Co., Ltd.: specific surface area value 15 m 2 100 parts by mass of zinc oxide (100 parts by mass / g) was mixed with 500 parts by mass of tetrahydrofuran and stirred, and 1.3 parts by mass of a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. Thereafter, the tetrahydrofuran was distilled off by reduced pressure distillation, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent. 110 parts by mass of zinc oxide that had been subjected to the above surface treatment was mixed with stirring in 500 parts by mass of tetrahydrofuran, and a solution in which 0.6 parts by mass of alizarin was dissolved in 50 parts by mass of tetrahydrofuran was added, followed by stirring for 5 hours at 50° C. Thereafter, the zinc oxide to which alizarin had been added was filtered out by filtration under reduced pressure, and further dried under reduced pressure at 60° C. to obtain zinc oxide to which alizarin had been added. A mixed solution was obtained by mixing 60 parts by mass of this alizarin-added zinc oxide, 13.5 parts by mass of a curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), 15 parts by mass of a butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) with 85 parts by mass of methyl ethyl ketone. 38 parts by mass of this mixed solution and 25 parts by mass of methyl ethyl ketone were mixed, and the mixture was dispersed for 2 hours in a sand mill using 1 mmφ glass beads to obtain a dispersion solution. To the resulting dispersion, 0.005 parts by mass of dioctyltin dilaurate as a catalyst and 40 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials, Inc.) were added to obtain a coating solution for the undercoat layer. This coating solution was applied to an aluminum substrate with a diameter of 60 mm, a length of 357 mm, and a thickness of 1 mm by a dip coating method, and dried and cured at 170°C for 40 minutes to obtain a 19 μm thick undercoat layer.

[0190] - Formation of charge generation layer - A mixture consisting of 15 parts by mass of hydroxygallium phthalocyanine as a charge generating material, which has diffraction peaks at Bragg angles (2θ±0.2°) at least 7.3°, 16.0°, 24.9°, and 28.0° in the X-ray diffraction spectrum using Cukα characteristic X-rays, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts by mass of n-butyl acetate was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the obtained dispersion and stirred to obtain a coating liquid for the charge generating layer. This coating liquid for the charge generating layer was dip-coated on the undercoat layer and dried at room temperature (25°C) to form a charge generating layer with a film thickness of 0.2 μm.

[0191] - Formation of charge transport layer - While keeping 95 parts by mass of tetrahydrofuran at a liquid temperature of 20°C, 10 parts by mass of (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-diphenyl)-4,4'-diamine, 10 parts by mass of bisphenol Z type polycarbonate resin (viscosity average molecular weight: 50,000) as a binder resin, and cyclic siloxane compound (1) in the content shown in Table 2 were added and mixed with stirring for 12 hours to obtain a coating liquid for forming a charge transport layer.

[0192] This charge transport layer forming coating liquid was applied onto the charge generation layer and dried at 135° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm. Through the above steps, a photoreceptor (1) was obtained in which an undercoat layer, a charge generation layer, and a charge transport layer were laminated in this order on an aluminum substrate.

[0193] [Examples 2 to 17, Comparative Examples 1 to 7] A photoreceptor was obtained in the same manner as in Example 1, except that the type and amount of the cyclic siloxane compound added in forming the charge transport layer were changed to those shown in Table 1. In Comparative Example 1, no cyclic siloxane compound was added.

[0194] Details of the cyclic siloxane compounds used in each example are given below. Compound (1): Specific example No. 1 of the aforementioned cyclic siloxane compound (X = succinic anhydride, number of X = 2, R = methyl group, n = 1) Compound (2): Example No. 8 of the aforementioned cyclic siloxane compound (X = succinic anhydride, number of X = 4, R = methyl group, n = 1) Compound (3): Specific example No. 9 of the aforementioned cyclic siloxane compound (X = acrylic group, number of X = 4, R = methyl group, n = 1) Compound (4): Specific example No. 2 of the above-mentioned cyclic siloxane compound (X = acrylic group, number of X = 2, R = methyl group, n = 1) Compound (5): Specific example No. 11 of the aforementioned cyclic siloxane compound (X = alicyclic epoxy group, number of X = 4, R = methyl group, n = 1) Compound (6): Specific example No. 4 of the above-mentioned cyclic siloxane compound (X = alicyclic epoxy group, number of X = 2, R = methyl group, n = 1) Compound (7): Specific example No. 13 of the above-mentioned cyclic siloxane compound (X = amino group, number of X = 4, R = methyl group, n = 1) · KP340: Silicone oil "KP340" manufactured by Shin-Etsu Chemical Co., Ltd.

[0195] -evaluation- The surface roughness Ra of the outermost layer of the photosensitive layer (that is, the charge transport layer) was measured by the above-mentioned method and evaluated according to the following criteria. A◎: Ra is 5 nm or less B〇: Ra is over 5nm and 10nm or less C△: Ra is over 10 nm and 15 nm or less D×: Ra is over 15 nm

[0196] [Table 2]

[0197] As shown in the table, it is clear that the electrophotographic photoreceptors of the Examples have reduced surface roughness Ra compared to the electrophotographic photoreceptors of the Comparative Examples.

[0198] The present embodiment includes the following aspects. (((1))) A substrate; A photosensitive layer on the substrate, An electrophotographic photoreceptor, wherein an outermost layer constituting the outermost surface contains at least one cyclic siloxane compound selected from the group consisting of cyclic siloxane compounds represented by the following general formulas (1), (2), (3) and (4) in a total amount of 0.0010 ppm or more: [ka] (In the above general formulas (1), (2), (3) and (4), R 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 Each of Z independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent. 11 , Z 12 , Z 21 , Z 22 , Z 23 , Z 31 , Z 32 , Z 33 , Z 34 , Z 41 , Z 42 , Z 43 , Z 44 , and Z 45 are each independently -Y 12 -X 12 X represents a group represented by the formula: 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42Y each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, an alicyclic epoxy group, an amino group, a hydroxyl group, and a glycidyl group. 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 each independently represents a divalent organic linking group. (((2))) The electrophotographic photoreceptor according to (((1))), wherein the outermost layer contains 0.0010 ppm or more in total of the cyclic siloxane compound represented by general formula (2). (((3))) In the cyclic siloxane compound represented by the general formula (2), 21 , Z 22 , and Z 23 One or three of the following are -Y 12 -X 12 The electrophotographic photoreceptor according to (((2))), wherein the group is represented by the formula: (((4))) In the cyclic siloxane compound represented by the general formula (2), 22 Ga-Y 12 -X 12 The Z 21 and Z 23 is a hydrogen atom or a monovalent alkyl group. (((5))) In the general formulas (1), (2), (3) and (4), the X 11 , X 12 , X 21 , X 22 , X 31 , X 32 , X 41 , and X 42 each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, and an amino group. (((6))) In the general formulas (1), (2), (3) and (4), the Y 11 , Y 12 , Y 21 , Y 22 , Y 31 , Y 32 , Y 41 , and Y 42 Each independently represents -(CH2) n The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein n represents a divalent organic linking group represented by - (wherein n is 1 or more and 8 or less). (((7))) In the general formulas (1), (2), (3) and (4), 11 , R 12 , R 13 , R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 , R 35 , R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 each independently represents a hydrogen atom or a monovalent alkyl group having from 1 to 10 carbon atoms which may have a substituent. (((8))) The electrophotographic photoreceptor according to any one of (((1))) to (((7))), containing the cyclic siloxane compounds in a total amount of 0.005 ppm or more and 20 ppm or less. (((9))) The electrophotographic photoreceptor according to (((8))), which contains the cyclic siloxane compounds in a total amount of 0.1 ppm or more and 15 ppm or less. (((10))) The electrophotographic photoreceptor according to any one of (((1))) to (((9))), wherein the outermost layer has a peripheral surface having a surface roughness Ra of 15 nm or less. (((11))) The electrophotographic photoreceptor according to (((10))), wherein the outer peripheral surface of the outermost layer has a surface roughness Ra of 1 nm or more and 10 nm or less. (((12))) The electrophotographic photoreceptor according to any one of (((1))) to (((11))) is provided, A process cartridge that is detachably attached to an image forming apparatus. (((13))) An electrophotographic photoreceptor according to any one of (((1))) to (((11))), a charging means for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing unit 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 means for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

[0199] According to the invention related to (((1))), (((6))) or (((7))), there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor containing 0.0010 ppm or more of only "KP340" manufactured by Shin-Etsu Chemical Co., Ltd. as a silicone oil in the outermost layer. According to the invention related to (((2))), there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor containing less than 0.0010 ppm in total of cyclic siloxane compounds represented by general formula (2) in the outermost layer. According to the invention related to (((3))) or (((4))), Z in the cyclic siloxane compound represented by general formula (2) 21 , Z 22 , and Z 23 0 or 2 of the characters are -Y 12 -X 12 In this way, an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface is provided, as compared with an electrophotographic photoreceptor having a group represented by the formula: According to the invention (((5))), the cyclic siloxane compound is represented by the general formula (2), 21, vX 22 As compared with an electrophotographic photoreceptor containing only a cyclic siloxane compound in which the cyclic epoxy group is an alicyclic epoxy group, an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface is provided. According to the invention related to (((8))) or (((9))), there is provided an electrophotographic photoreceptor having reduced roughness on the outer peripheral surface, as compared with an electrophotographic photoreceptor having a total content of cyclic siloxane compounds of less than 0.005 ppm. According to the invention related to (((10))) or (((11))), an electrophotographic photoreceptor is provided in which deterioration in cleaning performance is suppressed, as compared with an electrophotographic photoreceptor in which the outer peripheral surface of the outermost layer has a surface roughness Ra of more than 15 nm. According to the invention relating to (((12))) or (((13))), there are provided a process cartridge and an image forming apparatus which are equipped with an electrophotographic photoreceptor in which deterioration in cleaning performance is suppressed compared to when the electrophotographic photoreceptor contains only 0.0010 ppm or more of Shin-Etsu Chemical Co., Ltd.'s "KP340" as a silicone oil in the outermost layer. [Explanation of symbols]

[0200] 101 undercoat layer, 102 charge generating layer, 103 charge transport layer, 104 conductive substrate, 105 organic photosensitive layer, 107A, 7 electrophotographic photosensitive member (photosensitive member), 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 30 drive motor, 40 transfer device, 50 intermediate transfer body, 60 control device, 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. Substrate and The substrate has a photosensitive layer, An electrophotographic photoreceptor in which the outermost layer constituting the outermost surface contains at least one selected from the group consisting of cyclic siloxane compounds represented by the following general formulas (1), (2), (3), and (4) in a total amount of 0.0010 ppm or more. 【Chemistry 1】 (In the general formulas (1), (2), (3) and (4), R １１ , R １２ , R １３ , R ２１ , R ２２ , R ２３ , R ２４ , R ３１ , R ３２ , R ３３ , R ３４ , R ３５ , R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , and R ４６ each independently represents a hydrogen atom or a monovalent alkyl group which may have a substituent. Z １１ , Z １２ , Z ２１ , Z ２２ , Z ２３ , Z ３２ , Z ３３ , Z ３４ , Z ４１ , Z ４２ , Z ４３ , Z ４４ , and Z ４５ each independently represents a group represented by -Y １２ -X １２ , a hydrogen atom, or a monovalent alkyl group which may have a substituent. X １１ , X １２ , X ２１ , X ３１ , and X ４１ each independently represents a monovalent functional group selected from the group consisting of a succinic anhydride group, a (meth)acrylic group, an alicyclic epoxy group, an amino group, a hydroxyl group, and a glycidyl group. Y １１ , Y １２ , Y ２１ , Y ３１ , and Y ４１ each independently represents a divalent organic linking group.)

2. The outermost layer contains a total of 0.00 cyclic siloxane compounds represented by the general formula (2). The electrophotographic photoreceptor according to claim 1, containing 10 ppm or more.

3. In the cyclic siloxane compound represented by the general formula (2), the Z ２１ Z ２２ , and Z ２３ One or three of them are -Y １２ -X １２ The electrophotographic photoreceptor according to claim 2, wherein the base is represented by [the base].

4. In the cyclic siloxane compound represented by the general formula (2), the Z ２２ ga-Y １２ -X １２ The group is represented by the Z ２１ and Z ２３ The electrophotographic photoreceptor according to claim 3, wherein is a hydrogen atom or a monovalent alkyl group.

5. In the above general formulas (1), (2), (3), and (4), the X １１ , X １２ , X ２１ , X ３１ , and X ４１ The electrophotographic photoreceptor according to claim 1, wherein each independently represents a monovalent functional group selected from the group consisting of succinic anhydride groups, (meth)acrylic groups, and amino groups.

6. In the above general formulas (1), (2), (3), and (4), the Y １１ , Y １２ , Y ２１ , Y ３１ , and Y ４１ However, each independently, - (CH ２ ) ｎ The electrophotographic photoreceptor according to claim 1, which represents a divalent organic linking group (where n = 1 or more and 8 or less) represented by -.

7. In the above general formulas (1), (2), (3), and (4), the R １１ , R １２ , R １３ , R ２１ , R ２２ , R ２３ , R ２４ , R ３１ , R ３２ , R ３３ , R ３４ , R ３５ , R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , and R ４６ The electrophotographic photoreceptor according to claim 1, wherein each independently represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, which may have substituents.

8. The electrophotographic photoreceptor according to claim 1, further containing the cyclic siloxane compound in a total amount of 0.005 ppm or more and 20 ppm or less.

9. The electrophotographic photoreceptor according to claim 8, further containing the cyclic siloxane compound in a total amount of 0.1 ppm to 15 ppm.

10. The electrophotographic photoreceptor according to claim 1, wherein the surface roughness Ra of the outermost surface of the outermost layer is 15 nm or less.

11. The electrophotographic photoreceptor according to claim 10, wherein the surface roughness Ra of the outermost surface of the outermost layer is 1 nm or more and 10 nm or less.

12. The electrophotographic photoreceptor described in claim 1 comprises, A process cartridge that is attached to and detached from an image forming apparatus.

13. The electrophotographic photoreceptor according to claim 1, A charging means for charging the surface of the electrophotographic photoreceptor, An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, A developing means that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, A transfer means for transferring the toner image onto the surface of a recording medium, An image forming apparatus equipped with the following features.

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