Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Abstract

The invention relates to an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus. Provided is an electrophotographic photosensitive member including: a support; and a photosensitive layer. The photosensitive layer contains a binder resin, a charge generating substance, an electron transporting substance, and a hole transporting substance. The binder resin contains a polyaryl compound resin having a specific structural unit. The hole transport substance contains a specific compound.

Description

Technical Field

[0001] The present invention relates to an electrophotographic photosensitive member, a process cartridge including the electrophotographic photosensitive member, and an electrophotographic apparatus including the electrophotographic photosensitive member. Background Art

[0002] In recent years, there is a demand for electrophotographic apparatuses having a longer service life and capable of forming images of higher image quality, and it is desired to provide an apparatus having high stability in quality of output images even when used repeatedly (hereinafter sometimes referred to as "after endurance").

[0003] An organic electrophotographic photosensitive member (hereinafter sometimes referred to simply as "electrophotographic photosensitive member" or "photosensitive member") containing an organic photoconductive substance (charge generating substance) is used as an electrophotographic photosensitive member installed in an electrophotographic apparatus or in a process cartridge installed on the electrophotographic apparatus. In recent electrophotographic apparatuses, in order to cope with the above-mentioned longer service life, technologies for improving the durability of various components have been proposed.

[0004] For example, in each of Japanese Patent Application Laid-Open Nos. 2022-49733 and 2023-19706, a photosensitive member using a polyarylate resin (PAR) excellent in abrasion resistance as a binder resin in a photosensitive layer has been proposed.

[0005] According to studies conducted by the inventors of the present invention, in the photosensitive member described in each of Japanese Patent Application Laid-Open Nos. 2022-49733 and 2023-19706 using a polyarylate resin for the purpose of improving durability, there is room for improvement in suppressing a decrease in sensitivity during repeated use. Summary of the invention

[0006] Therefore, an object of the present invention is to provide an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus which have high durability and suppress a decrease in sensitivity when repeatedly used.

[0007] The above-mentioned object is achieved by the present invention described below. That is, according to one aspect of the present invention, there is provided an electrophotographic photosensitive member comprising: a support; and a photosensitive layer, wherein the photosensitive layer comprises: a binder resin, a charge generating substance, an electron transporting substance, and a hole transporting substance, wherein the binder resin comprises a polyarylate resin having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3), and a structural unit represented by the following formula (4):

[0008]

[0009] And wherein the hole transporting substance comprises a compound represented by the following formula (5):

[0010]

[0011] In formula (5), R 1 represents an alkyl group having 2 or more and 4 or less carbon atoms, and Ar 1 It represents an aryl group which may have an alkyl group having 1 to 4 carbon atoms as a substituent.

[0012] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0014] Figure 2 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0015] Figure 3 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0016] Figure 4 is a diagram for illustrating an example of a schematic configuration of an electrophotographic apparatus according to the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below by way of exemplary embodiments.

[0018] In the electrophotographic photosensitive member described in each of Japanese Patent Applications No. 2022-49733 and No. 2023-19706, a polyarylate resin is used as a binder resin in the photosensitive layer to improve durability. At the same time, as a result of research conducted by the inventors, it has been found that in the electrophotographic photosensitive member described in each of Japanese Patent Applications No. 2022-49733 and 2023-19706, the sensitivity is low from the beginning and further decreases during repeated use. The reasons for the foregoing are considered to be as follows. Due to strong resin interactions, the polyarylate resin that contributes to the high durability of the electrophotographic photosensitive member has low compatibility with the hole transporting substance and cannot be properly mixed therewith. Therefore, the hole extraction ability and hole transporting ability of the hole transporting substance are reduced, and the holes cannot flow smoothly, resulting in reduced sensitivity. In addition, it has been found that in the electrophotographic photosensitive member described in Japanese Patent Application Laid-Open No. 2022-49733, image smear, which is one of the image defects, is easily caused by repeated use. The inventors speculate that the reason for the foregoing is as follows. The photosensitive layer containing the polyarylate resin has high wear resistance, so the discharge product generated on the surface of the photosensitive member cannot be properly removed during cleaning.

[0019] Based on the above assumptions, the present inventors have conducted various studies on means for suppressing the occurrence of image offset while maintaining high sensitivity during repeated use in a highly durable electrophotographic photosensitive member using a polyarylate resin as a binder resin in a photosensitive layer, and have arrived at the present invention.

[0020] That is, the electrophotographic photosensitive member according to the present invention comprises a support and a photosensitive layer, and the photosensitive layer comprises a binder resin, a charge generating substance, an electron transporting substance, and a hole transporting substance. In addition, the binder resin comprises a polyarylate resin having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3), and a structural unit represented by the following formula (4).

[0021]

[0022] Furthermore, the hole transporting substance contains a compound represented by the following formula (5).

[0023]

[0024] In formula (5), R 1 represents an alkyl group having 2 or more and 4 or less carbon atoms, and Ar 1 It represents an aryl group which may have an alkyl group having 1 to 4 carbon atoms as a substituent.

[0025] The present inventors have found that when the electrophotographic photosensitive member has the above-described constitution according to the present invention, high sensitivity can be maintained during repeated use, and the occurrence of image offset can be suppressed while achieving high durability.

[0026] The inventors speculate that the reasons for the above situation are as follows. Due to strong resin interactions, the polyarylate resin having each structural unit represented by formulas (1), (2), (3) and (4) has low compatibility with hole transport substances having a small amount of heteroatoms in the molecule and having low polarity. However, the hole transport substance represented by formula (5) has a phenoxy structure, so this type of hole transport substance has high compatibility with the polyarylate resin and at the same time has a low ionization potential. It can be seen that the hole transport substance represented by formula (5) has an improved hole extraction ability. Therefore, the holes flow smoothly without being retained, and high sensitivity can be maintained during repeated use. In addition, the high compatibility between the above-mentioned polyarylate resin and the hole transport substance suppresses the uneven microelectrical resistance on the surface of the photosensitive member. Therefore, the discharge becomes uniform, and the generation of discharge products caused by local large currents caused by uneven discharge can be suppressed. As a result, the occurrence of image smear can be suppressed.

[0027] The constitution of the electrophotographic photosensitive member according to the present invention is described below in more detail.

[0028] [Electrophotographic photosensitive member]

[0029] The electrophotographic photosensitive member according to the present invention includes a support and a photosensitive layer formed on the support.

[0030] The method for producing the electrophotographic photosensitive member according to the present invention is, for example, a method involving: preparing a coating liquid for each layer described later; applying the liquid in the desired order of the layers; and drying the liquid. In this case, examples of the method for applying the coating liquid include dip coating, spray coating, inkjet coating, roller coating, die coating, blade coating, curtain coating, wire rod coating, and ring coating. Among them, dip coating is preferred from the viewpoint of efficiency and productivity.

[0031] (Single-layer type photosensitive member)

[0032] Refer to the following Figures 1 to 3 A single-layer type photosensitive member 1 according to an embodiment of the present invention is described. Figures 1 to 3 Each is a partial cross-sectional view for illustrating an example of the layer constitution of the single-layer type photosensitive member 1 .

[0033] like Figure 1As shown, the single-layer photosensitive member 1 includes, for example, a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 included in the single-layer photosensitive member 1 is a single-layer (one-layer) single-layer photosensitive layer. The photosensitive layer 3 contains a binder resin, a charge generating substance, an electron transporting substance, and a hole transporting substance.

[0034] like Figure 2 As shown in FIG. 1 , the single-layer photosensitive member 1 may further include an undercoat layer 4 (intermediate layer) in addition to the support 2 and the photosensitive layer 3. That is, in the single-layer photosensitive member 1, the photosensitive layer 3 may be directly formed on the support 2, or may be formed as shown in FIG. Figure 2 The substrate is shown to be formed on the support 2 via the primer layer 4 .

[0035] In addition, if Figure 3 As shown in FIG. 1 , the single-layer type photosensitive member 1 may further include a protective layer 5 in addition to the support 2 and the photosensitive layer 3. The protective layer 5 is formed on the photosensitive layer 3. In the present invention, Figure 1 and Figure 2 As shown in each of the above, it is preferred that the single-layer photosensitive member 1 does not include the protective layer 5 and the photosensitive layer 3 is formed as a surface layer of the single-layer photosensitive member 1. When the photosensitive layer 3 containing the polyarylate resin (PAR) having each structural unit represented by formulae (1) to (4) as a binder resin is formed as a surface layer, the effect of the present invention is easily obtained during repeated use.

[0036] The thickness of the photosensitive layer 3 is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0037] <Support>

[0038] In the present invention, the electrophotographic photosensitive member includes a support. In the present invention, the support is preferably a conductive support having conductivity. In addition, examples of the shape of the support include cylindrical, belt-like, and sheet-like. Among these shapes, a support having a cylindrical shape is preferred. In addition, the surface of the support may be subjected to, for example, electrochemical treatment such as anodizing, sandblasting, or cutting treatment.

[0039] As a material for the support, metal, resin, glass or the like is preferable.

[0040] Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof Among these metals, an aluminum support using aluminum is preferred.

[0041] Furthermore, conductivity may be imparted to the resin or glass through a process involving, for example, mixing the resin or glass with a conductive material or coating the resin or glass with a conductive material.

[0042] <Base Coating>

[0043] In the present invention, an undercoat layer may be provided on the support. The undercoat layer may improve the interlayer adhesion function and impart a charge injection suppression function.

[0044] The primer layer preferably contains a resin. In addition, the primer layer can be formed into a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

[0045] Examples of the resin include polyester resins, polyarylate resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinylphenolic resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide resins, polyamic acid resins, polyimide resins, polyamideimide resins, and cellulose resins.

[0046] Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0047] In order to improve electrical characteristics, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, a conductive polymer, etc. Among them, an electron transporting substance and a metal oxide are preferably used.

[0048] Examples of electron transporting substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds and boron-containing compounds. An electron transporting substance having a polymerizable functional group can be used as the electron transporting substance and copolymerized with the above-mentioned monomer having a polymerizable functional group to form a primer layer as a cured film.

[0049] Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of metals include gold, silver, and aluminum.

[0050] In addition, the undercoat layer may further contain additives.

[0051] The thickness of the undercoat layer is preferably 0.1 μm to 50 μm, more preferably 0.2 μm to 40 μm, particularly preferably 0.3 μm to 30 μm.

[0052] The undercoat layer can be formed by preparing an undercoat layer coating solution containing the above-mentioned substances and a solvent; forming a coating film of the coating solution; and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0053] <Single-layer photosensitive layer>

[0054] The electrophotographic photosensitive member according to the present invention includes a single-layer type photosensitive layer provided on a support, or on an undercoat layer provided on a support.

[0055] In the present invention, the single-layer type photosensitive layer contains a binder resin, a charge generating substance, a hole transporting substance, and an electron transporting substance.

[0056] [Binder resin]

[0057] The binder resin used in the photosensitive layer contains a polyarylate resin having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3) and a structural unit represented by the following formula (4).

[0058]

[0059] The above-mentioned polyarylate resin may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer or a block copolymer.

[0060] In the above-mentioned polyarylate resin, the ratio of the amount of the structural unit represented by formula (1) to the total amount of the structural units forming the polyarylate resin is represented by M1. In addition, the ratio of the amount of the structural unit represented by formula (2) to the total amount of the structural units forming the polyarylate resin is represented by M2. In addition, the ratio of the amount of the structural unit represented by formula (3) to the total amount of the structural units forming the polyarylate resin is represented by M3. In addition, the ratio of the amount of the structural unit represented by formula (4) to the total amount of the structural units forming the polyarylate resin is represented by M4. The amounts are measured in moles. In this case, from the viewpoint of improving wear resistance, M1 / (M1+M3) is preferably 0.30 or more, more preferably 0.55 or more.

[0061] In addition, from the viewpoint of improving abrasion resistance, M2 / (M2+M4) is preferably larger, and specifically, preferably 0.10 or more. In addition, from the viewpoint of solubility in a solvent, M2 / (M2+M4) is preferably less than 0.50. When the solubility in a solvent is improved, a photosensitive layer can be satisfactorily formed. Therefore, M2 / (M2+M4) is preferably 0.10 or more and less than 0.50.

[0062] Furthermore, from the viewpoint of suppressing a decrease in sensitivity, M3 / (M1+M3) is preferably 0.30 or more and less than 0.70.

[0063] Furthermore, from the viewpoint of improving solubility in a solvent, M4 / (M2+M4) is preferably less than 0.90.

[0064] In the above-mentioned polyarylate resin, the sum of the ratio of the amount of the structural unit represented by formula (1) to the total amount of the structural unit derived from the dicarboxylic acid used to form the polyarylate resin and the ratio of the amount of the structural unit represented by formula (3) to the total amount of the structural unit derived from the dicarboxylic acid used to form the polyarylate resin is preferably 0.30 or more, more preferably 0.50 or more.

[0065] In the above-mentioned polyarylate resin, the sum of the ratio of the amount of the structural unit represented by formula (2) to the total amount of the structural unit derived from the bisphenol used to form the polyarylate resin and the ratio of the amount of the structural unit represented by formula (4) to the total amount of the structural unit derived from the bisphenol used to form the polyarylate resin is preferably greater than 0 and less than 0.50.

[0066] The ratio of the amount of the structural unit represented by the formula (1) to the total amount of the structural units derived from the dicarboxylic acid used to form the polyarylate resin is preferably 0.50 or more.

[0067] Furthermore, in the electrophotographic photosensitive member according to the present invention, the ratio of the mass of the above-mentioned polyarylate resin to the total mass of the binder resin is preferably 50% by mass or more.

[0068] The viscosity average molecular weight of the polyarylate resin (PAR) is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. When the viscosity average molecular weight of the polyarylate resin (PAR) is 10,000 or more, the wear resistance of the photosensitive member is improved. Meanwhile, the viscosity average molecular weight of the polyarylate resin (PAR) is preferably 80,000 or less, more preferably 70,000 or less. When the viscosity average molecular weight of the polyarylate resin (PAR) is 80,000 or less, the polyarylate resin (PAR) is easily dissolved in a solvent for forming a photosensitive layer.

[0069] Examples of bisphenols used to form the repeating units derived from bisphenol in the above-mentioned polyarylate resin include compounds represented by the following formula (BP-1) and compounds represented by the following formula (BP-2). The compound represented by the following formula (BP-1) is sometimes referred to as "compound (BP-1)" below. In addition, the compound represented by the following formula (BP-2) is sometimes referred to as "compound (BP-2)" below.

[0070]

[0071] In addition, examples of dicarboxylic acids used to form repeating units derived from dicarboxylic acids in the above-mentioned polyarylate resin include compounds represented by the following formula (DC-1) and compounds represented by the following formula (DC-2). The compound represented by the following formula (DC-1) is sometimes referred to as "compound (DC-1)" below. In addition, the compound represented by the following formula (DC-2) is sometimes referred to as "compound (DC-2)" below.

[0072]

[0073] When producing the above polyarylate resin (PAR), the bisphenol ratio in the resin can be adjusted by changing the amounts of the compound (BP-1) and the compound (BP-2) to be added. In addition, when producing the above polyarylate resin (PAR), the dicarboxylic acid ratio in the resin can be similarly adjusted by changing the amounts of the compound (DC-1) and the compound (DC-2) to be added.

[0074] Bisphenols (e.g., compounds (BP-1) and (BP-2)) can each be used by derivatization to aromatic diacetates. Dicarboxylic acids (e.g., compounds (DC-1) and (DC-2)) can each be used by derivatization. Examples of derivatives of dicarboxylic acids include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. Dicarboxylic acid dichlorides are compounds having a structure in which two "-C(=O)-OH" groups of dicarboxylic acids are each substituted with a "-C(=O)-Cl" group.

[0075] In the polycondensation of bisphenol and dicarboxylic acid, one or both of a base and a catalyst may be added. An example of the base is sodium hydroxide. Examples of the catalyst include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

[0076] The photosensitive layer may contain only the above-mentioned polyarylate resin (PAR) as a binder resin, and may further contain a binder resin other than the above (hereinafter sometimes referred to as "other binder resin"). When the photosensitive layer contains other binder resins in addition to the above-mentioned polyarylate resin, the ratio of the mass of the above-mentioned polyarylate resin to the total mass of the binder resins in the photosensitive layer is preferably 0.8 or more.

[0077] Examples of other binder resins include: thermoplastic resins (more specifically, polyarylate resins other than the above-mentioned polyarylate resin (PAR), polycarbonate resins, styrene resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins); thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and any other crosslinking thermosetting resins); and photocurable resins (more specifically, epoxy-acrylic resins and urethane-acrylic copolymers).

[0078] The structure of the polyarylate resin used in the present invention can be obtained by treating the high molecular weight components recovered from the photosensitive layer in deuterated chloroform. 1 H-NMR spectroscopy analysis 1 determined by H-NMR spectroscopy.

[0079] An example of a specific analysis method of the polyarylate resin in the photosensitive layer when the photosensitive member is a cylindrical body is described below.

[0080] (Reprecipitation of resin in photosensitive layer)

[0081] The photosensitive member was cut with a wire saw at a position 10 cm away from the end of the photosensitive member in the generatrix direction.

[0082] • Wipe the inner surface of the cut 10 cm cylinder with lens cleaning paper soaked in chloroform.

[0083] To wash off the photosensitive layer, 3 cm of the end of the cut cylinder was immersed in chloroform. (Put about 60 mL of chloroform in a 100 mL beaker and immerse the end therein for 5 minutes at room temperature.)

[0084] The chloroform solution containing the photosensitive layer was concentrated to 2 mL using a rotary evaporator, and the concentration was stopped.

[0085] 50 mL of a methanol / acetone mixed solution (volume ratio of 1:1) was prepared, and the entire amount of the concentrated solution was dropped therein while stirring the mixed solution, thereby performing reprecipitation.

[0086] Suction filtration was performed using a funnel (funnel: SU-40, filter paper: No. 5C-40, manufactured by Kiriyama Glass Co.).

[0087] The residue on the filter paper was recovered with a scraper and dried in vacuum (70°C, 1 hour).

[0088] (NMR measurement)

[0089] To prepare a measurement sample, 20 mg of a sample is dissolved in 1 g of deuterated chloroform containing tetramethylsilane as a reference substance, and the entire amount thereof is transferred to an NMR tube.

[0090] (Deuterated chloroform: manufactured by Sigma-Aldrich Japan GK, Chloroform-d, model: 612200)

[0091] (NMR tube: manufactured by Norell, Inc., ST500-7, model: S3010)

[0092] • Perform NMR measurements.

[0093] Equipment: AVANCE 500 manufactured by Bruker

[0094] Conditions: Proton NMR, automated measurement by Icon-NMR

[0095] Scan times: 32

[0096] Reference peak: The methyl peak of tetramethylsilane was set to 0 ppm.

[0097] [Hole transport substances]

[0098] The hole transporting substance includes a compound represented by the following formula (5).

[0099]

[0100] In formula (5), R 1 represents an alkyl group having 2 or more and 4 or less carbon atoms, and Ar 1 It represents an aryl group which may have an alkyl group having 1 to 4 carbon atoms as a substituent.

[0101] In formula (5), R 1 Examples of the alkyl group represented include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

[0102] Ar in formula (5) 1 Preferably, it represents a phenyl group which may have an alkyl group as a substituent. 1 The number of substituents of the aryl group represented by is preferably 0 or 1, and more preferably 0. 1Examples of the substituent of the aryl group represented by include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

[0103] Suitable examples of the compound represented by formula (5) include the compounds shown in Table 1. The compounds represented by formula (5) shown as examples in Table 1 are hereinafter sometimes referred to as "hole transport substances (H-1) to (H-10)", respectively.

[0104] Regarding the compound represented by formula (5), 1 H-NMR spectroscopy can be performed by 1 As a result, the structure represented by formula (5) was determined.

[0105] Table 1

[0106]

[0107] In Table 1, Me represents a methyl group, Et represents an ethyl group, n-Pr represents an n-propyl group, i-Pr represents an isopropyl group, n-Bu represents an n-butyl group, and t-Bu represents a tert-butyl group.

[0108] The content of the hole transport substance in the photosensitive layer is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 30 parts by mass or more and 120 parts by mass or less, and still more preferably 50 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0109] The photosensitive layer may further contain one or more hole transport substances other than the compound represented by formula (5) (hereinafter sometimes referred to as "other hole transport substances"). Examples of other hole transport substances include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthalenediamine derivatives, N,N,N',N'-tetraphenylphenanthrenediamine derivatives and di(aminophenylvinyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-bis(4-methylaminophenyl)-1,3,4-oxadiazole), styryl compounds (e.g., 9-(4-diethylaminostyryl)anthracene), carbazole compounds (e.g., polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (e.g., 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds.

[0110] It is preferred that the ratio of the amount of the compound represented by formula (5) in the photosensitive layer to the total amount of all hole transport substances in the photosensitive layer, the amount of the substance being calculated in moles, is 0.6 or more.

[0111] It is preferred that the content of the compound represented by formula (5) in the photosensitive layer is 50% by mass or more relative to the total amount of hole transporting substances in the photosensitive layer.

[0112] [Charge generating material]

[0113] Examples of the charge generating material include phthalocyanine pigments, perylene pigments, disazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaric acid pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one charge generating material, or may contain two or more charge generating materials.

[0114] Phthalocyanine pigments are pigments having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include oxytitanium phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine. Metal phthalocyanine is preferably oxytitanium phthalocyanine. Oxytitanium phthalocyanine is represented by the following formula (CGM-1).

[0115]

[0116] Phthalocyanine pigments may be crystalline or non-crystalline. Examples of crystals of metal-free phthalocyanine are X-type crystals of metal-free phthalocyanine (hereinafter sometimes referred to as "X-type metal-free phthalocyanine"). Examples of crystals of oxytitanium phthalocyanine include α-type, β-type and Y-type crystals of oxytitanium phthalocyanine (hereinafter sometimes referred to as "α-type, β-type and Y-type oxytitanium phthalocyanine", respectively). For example, in digital optical electrophotographic equipment (for example, a laser beam printer or fax machine using a light source such as a semiconductor laser), it is preferred to use a photosensitive member having sensitivity in a wavelength region of 700 nm or more. The charge generating substance is preferably a phthalocyanine pigment, and more preferably a metal-free phthalocyanine or oxytitanium phthalocyanine, because these substances each have a high quantum yield in a wavelength region of 700 nm or more. In addition, the charge generating substance is more preferably oxytitanium phthalocyanine, and particularly preferably Y-type oxytitanium phthalocyanine.

[0117] In the CuKα characteristic X-ray diffraction spectrum, Y-type oxytitanium phthalocyanine has no peak at 26.2° and has a main peak at a Bragg angle (2θ±0.2°) of 27.2°, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second maximum intensity within the range of the Bragg angle (2θ±0.2°) being 3° or more and 40° or less.

[0118] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample (oxytitanium phthalocyanine) is loaded into a sample holder of an X-ray diffraction apparatus (for example, "RINT (trademark) 1100" manufactured by Rigaku Corporation). Then, the CuKα characteristic X-ray spectrum is measured under the conditions of Cu as the X-ray tube, 40 kV as the tube voltage, 30 mA as the tube current, and a CuKα characteristic X-ray wavelength of 1.5 Å. The X-ray diffraction spectrum is measured under the conditions of . The measurement range (2θ) is, for example, 3° or more and 40° or less (start angle: 3° and end angle: 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0119] The content of the charge generating substance in the photosensitive layer is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0120] [Electron transport substances]

[0121] It is preferred that the electron transporting substance contains at least one compound selected from the group consisting of: a compound represented by the following formula (6); a compound represented by the following formula (7); a compound represented by the following formula (8); a compound represented by the following formula (9); a compound represented by the following formula (10); a compound represented by the following formula (11); and a compound represented by the following formula (12). It is believed that when the photosensitive layer contains the above-mentioned electron transporting substance, the compatibility between the above-mentioned polyarylate resin and the compound represented by formula (5) is improved to enhance the uniformity inside the photosensitive layer, thereby highly achieving the effect of the present invention.

[0122]

[0123]

[0124] Q in formula (6) 1 and Q 2 , Q in formula (7) 11 , Q 12 and Q 13 , Q in formula (8) 21 , Q 22 , Q 23 and Q24 , Q in formula (9) 31 and Q 32 , Q in formula (10) 41 , Q 42 , Q 43 and Q 44 , Q in formula (11) 51 , Q 52 , Q 53 , Q 54 , Q 55 and Q 56 , and Q in formula (12) 61 and Q 62 Each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 Each independently represents an oxygen atom or a sulfur atom.

[0125] Preferably, Q in formula (6) 1 and Q 2 , Q in formula (7) 11 To Q 13 , Q in formula (8) 21 To Q 24 , Q in formula (9) 31 and Q 32 , Q in formula (10) 41 To Q 44 , Q in formula (11) 51 To Q 56 And Q in formula (12) 61 and Q 62 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 Each represents an oxygen atom.

[0126] From Q in formula (6) 1 and Q 2 , Q in formula (7) 11 To Q 13 , Q in formula (8) 21 To Q 24 , Q in formula (9) 31and Q 32 , Q in formula (10) 41 To Q 44 , Q in formula (11) 51 To Q 56 And Q in formula (12) 61 and Q 62 The alkyl group having 1 to 6 carbon atoms each represented is preferably an alkyl group having 1 to 5 carbon atoms, preferably a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group, and particularly preferably a methyl group, an isopropyl group, a tert-butyl group or a 1,1-dimethylpropyl group.

[0127] From Q in formula (6) 1 and Q 2 , Q in formula (7) 11 To Q 13 , Q in formula (8) 21 To Q 24 , Q in formula (9) 31 and Q 32 , Q in formula (10) 41 To Q 44 , Q in formula (11) 51 To Q 56 And Q in formula (12) 61 and Q 62 The aryl group having 6 to 14 carbon atoms each represented is preferably an aryl group having 6 to 10 carbon atoms, and more preferably a phenyl group.

[0128] Here, the alkyl group having 1 to 6 carbon atoms which can be a substituent of the aryl group having 6 to 14 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group.

[0129] The halogen atom which can be a substituent of the aryl group having 6 to 14 carbon atoms is preferably a fluorine atom, a chlorine atom or a bromine atom, and particularly preferably a chlorine atom.

[0130] When the aryl group having 6 to 14 carbon atoms is substituted by a substituent, the number of the substituent is preferably 1 to 5, and more preferably 1 or 2.

[0131] The aryl group having 6 to 14 carbon atoms substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom is preferably a chlorophenyl group, a dichlorophenyl group or an ethylmethylphenyl group, and more preferably a 4-chlorophenyl group, a 2,5-dichlorophenyl group or a 2-ethyl-6-methylphenyl group.

[0132] A suitable example of the compound represented by formula (6) is a compound represented by the following formula (E-4). A suitable example of the compound represented by formula (7) is a compound represented by the following formula (E-5). A suitable example of the compound represented by formula (8) is a compound represented by the following formula (E-7). A suitable example of the compound represented by formula (9) is a compound represented by the following formula (E-6). A suitable example of the compound represented by formula (10) is a compound represented by the following formula (E-8). Suitable examples of the compound represented by formula (11) include a compound represented by the following formula (E-2) and a compound represented by the following formula (E-3). A suitable example of the compound represented by formula (12) is a compound represented by the following formula (E-1). The compounds represented by formulas (E-1) to (E-8) are sometimes referred to as "electron transport substances (E-1) to (E-8)", respectively.

[0133]

[0134]

[0135]

[0136] The content of the electron transporting substance in the photosensitive layer is preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 100 parts by mass or less, and still more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the binder resin. The photosensitive layer may contain only one electron transporting substance, or may contain two or more electron transporting substances.

[0137] [additive]

[0138] The photosensitive layer may include additives as needed. Examples of additives include UV absorbers, antioxidants, free radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, waxes, donors, surfactants, plasticizers, sensitizers and leveling agents. In particular, it is preferred that the photosensitive layer include at least one compound selected from the group consisting of: a compound represented by the following formula (T-1), a compound represented by the following formula (T-2), a compound represented by the following formula (T-3) and a compound represented by the following formula (T-4). "t-Bu" in each of formulas (T-2), (T-3) and (T-4) represents a tert-butyl group.

[0139] The content ratio of the additive in the photosensitive layer is preferably 0.1% by mass or more and 10% by mass or less relative to the total mass of the photosensitive layer.

[0140]

[0141] Next, a process cartridge and an electrophotographic apparatus according to the present invention are described.

[0142] The process cartridge according to the present invention is characterized by integrally supporting the above-mentioned electrophotographic photosensitive member and at least one unit selected from the group consisting of a charging unit, a developing unit and a cleaning unit, and is detachably mountable to a main body of an electrophotographic apparatus.

[0143] Furthermore, an electrophotographic apparatus according to the present invention is characterized by including the above-mentioned electrophotographic photosensitive member, and a charging unit, an exposure unit, a developing unit, and a transfer unit.

[0144] The charging unit may be a charging unit configured to positively charge the electrophotographic photosensitive member.

[0145] [Electronic photography equipment]

[0146] An example of the constitution of the electrophotographic apparatus according to the present invention is described in detail below.

[0147] Refer to the following Figure 4 A tandem type color electrophotographic apparatus is described as an example. Figure 4 is a cross-sectional view for illustrating an example of the configuration of an electrophotographic apparatus. Figure 4 The illustrated electrophotographic apparatus 100 includes image forming units 40a, 40b, 40c, and 40d, a transfer belt 50, and a fixing device 54. When no distinction is required, each of the image forming units 40a, 40b, 40c, and 40d is hereinafter referred to as an "image forming unit 40". The image forming unit 40 includes an image bearing member 30, a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The image bearing member 30 is a photosensitive member (specifically, a single-layer photosensitive member 1). In addition, a recording medium P is located at a lower portion of the electrophotographic apparatus. The image bearing member 30 is disposed at a central position of the image forming unit 40. The image bearing member 30 is disposed so as to be movable in the direction of the arrow ( Figure 4 The charging device 42, the exposure device 44, the developing device 46, and the transfer device 48 are arranged around the image bearing member 30 in the stated order from the upstream side in the rotation direction of the image bearing member 30.

[0148] By the respective image forming units 40 a to 40 d , toner images of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) are sequentially superimposed on the recording medium P on the transfer belt 50 .

[0149] The charging device 42 charges the surface (eg, circumferential surface) of the image bearing member 30 to positive polarity. When the image bearing member 30 is a single-layer type photosensitive member 1, the surface of the image bearing member 30 is charged to positive polarity. The charging device 42 is, for example, a charging roller.

[0150] The exposure device 44 irradiates the surface of the charged image bearing member 30 with exposure light. That is, the exposure device 44 exposes the surface of the charged image bearing member 30. As a result, an electrostatic latent image is formed on the surface of the image bearing member 30. The electrostatic latent image is formed based on the image data input to the electrophotographic apparatus 100.

[0151] The developing device 46 supplies the toner to the surface of the image bearing member 30, thereby developing the electrostatic latent image into a toner image. The developing device 46 (for example, the surface of the developing device 46, more specifically, the circumferential surface of the developing device 46) is in contact with the surface of the image bearing member 30. That is, the electrophotographic apparatus 100 adopts a contact developing system. The developing device 46 is, for example, a developing roller. When the developer is a single-component developer, the developing device 46 supplies the toner as the single-component developer to the electrostatic latent image formed on the image bearing member 30. When the developer is a two-component developer, the developing device 46 supplies the toner contained in the two-component developer and the toner in the carrier to the electrostatic latent image formed on the image bearing member 30. In this way, the image bearing member 30 carries the toner image.

[0152] The transfer belt 50 conveys the recording medium P to a position between the image bearing member 30 and the transfer device 48. The transfer belt 50 is an endless belt. The transfer belt 50 is arranged so as to be movable in the direction of the arrow ( Figure 4 The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image bearing member 30 to the transfer target member. The transfer target member is the recording medium P. When the toner image is transferred, the image bearing member 30 is in contact with the recording medium P. That is, the electronic photographic apparatus 100 adopts a direct transfer system. The transfer device 48 is, for example, a transfer roller. The recording medium P having the toner image transferred thereto by the transfer device 48 is conveyed to the fixing device 54 by the transfer belt 50.

[0153] The fixing device 54 is, for example, a heating roller and / or a pressure roller. The unfixed toner image transferred by the transfer device 48 is heated and / or pressed by the fixing device 54. The toner image is fixed to the recording medium P by being heated and / or pressed. As a result, an image is formed on the recording medium P.

[0154] An example of an electrophotographic apparatus has been described above, but the electrophotographic apparatus is not limited to the above-mentioned electrophotographic apparatus 100. The above-mentioned electrophotographic apparatus 100 is a color electrophotographic apparatus, but the electrophotographic apparatus may also be a monochrome electrophotographic apparatus. In this case, it is only necessary that the electrophotographic apparatus includes, for example, only one image forming unit.

[0155] Furthermore, the above-described electrophotographic apparatus 100 adopts a tandem system, but the electrophotographic apparatus may also adopt, for example, a rotary system.

[0156] The charging device 42 has been described by taking the charging roller as an example, but the charging device may be a charging device other than the charging roller (e.g., a scorotron charger, a charging brush, or a corotron charger). The above-mentioned electrophotographic apparatus 100 adopts a contact developing system, but the electrophotographic apparatus may also adopt a non-contact developing system.

[0157] The above-mentioned electrophotographic apparatus 100 adopts a direct transfer system, but the electrophotographic apparatus may also adopt an intermediate transfer system. When the electrophotographic apparatus adopts an intermediate transfer system, the transfer target member corresponds to the intermediate transfer belt. In the electrophotographic apparatus, the above-mentioned image forming unit 40 does not include a cleaning member, but the image forming unit may further include a cleaning member (e.g., a cleaning blade).

[0158] The above-described image forming unit 40 does not include a static eliminating device, but the image forming unit may further include a static eliminating device.

[0159] [Processing cartridge]

[0160] Next, continue to refer to Figure 4 , describes an example of the composition of the process cartridge according to the present invention. Each image forming unit 40a to 40d includes a process cartridge. The process cartridge includes an image bearing member 30. The image bearing member 30 is a photosensitive member (specifically, a single-layer photosensitive member 1). In addition to the image bearing member 30, the process cartridge further includes at least one selected from the group consisting of a charging device 42, a developing device 46, and a cleaning member (not shown).

[0161] The process cartridge is designed to be detachably mounted on the electrophotographic apparatus 100. Therefore, the process cartridge is easy to handle and the process cartridge and the image bearing member 30 can be easily and quickly replaced when the sensitivity characteristics of the image bearing member 30, etc., are deteriorated. Figure 4 A process cartridge including a photosensitive member is described.

[0162] According to the present invention, it is possible to provide an electrophotographic photosensitive member having high durability and in which a decrease in sensitivity during repeated use is suppressed.

[0163] [Example]

[0164] The present invention is described in more detail below by examples and comparative examples.Within the scope of not departing from the gist of the present invention, the present invention is by no means restricted by the following examples.In the description of the following examples, unless otherwise indicated, the term "part" is by mass.

[0165] <Production of Polyarylate Resin (PAR)>

[0166] [Synthesis of resin (PAR-1)]

[0167] A three-necked flask including a thermometer, a three-way stopcock and a dropping funnel was used as a reaction vessel.

[0168] First, prepare the following materials.

[0169] ·Compound (BP-2) as a monomer (28.7 mmol)

[0170] ·Compound (BP-1) as a monomer (12.3 mmol)

[0171] · 2,6-Dimethylphenol (DMP) as an end terminator (0.413 mmol)

[0172] Sodium hydroxide (98 mmol)

[0173] Benzyltributylammonium chloride (0.384 mmol)

[0174] The above substances were charged into a reaction vessel, and the air in the reaction vessel was replaced with argon. Water (300 mL) was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50° C. for 1 hour. The contents of the reaction vessel were cooled to 10° C. to provide an alkaline aqueous solution A.

[0175] Next, dicarboxylic acid dichloride (20.8 mmol) of compound (DC-1) as a monomer and dicarboxylic acid dichloride (11.2 mmol) of compound (DC-2) as a monomer were dissolved in chloroform (150 mL). As a result, chloroform solution B was obtained.

[0176] Chloroform solution B was slowly dripped into alkaline aqueous solution A by using a dropping funnel over 110 minutes. While the temperature (liquid temperature) of the contents of the reaction vessel was adjusted to 15 ± 5 ° C, the contents of the reaction vessel were stirred for 4 hours to allow the polymerization reaction to proceed. The upper layer (water layer) of the contents of the reaction vessel was removed by decantation. Thus, an organic layer was obtained. Next, ion exchange water (400mL) was loaded into an Erlenmeyer flask. The obtained organic layer was further added to an Erlenmeyer flask. Chloroform (400mL) and acetic acid (2mL) were further added to an Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25 ° C) for 30 minutes. The upper layer (water layer) of the contents of the Erlenmeyer flask was removed by decantation. Thus, an organic layer was obtained. The obtained organic layer was washed with ion exchange water (1L) using a separatory funnel. The washing with ion exchange water was repeated 5 times. Thus, a washed organic layer was obtained. Next, the washed organic layer was filtered to provide a filtrate. The obtained filtrate was slowly dropped into methanol (1 L) to provide a precipitate. The precipitate was taken out by filtration. The precipitate thus taken out was vacuum dried at a temperature of 70° C. for 12 hours. As a result, a resin (PAR-1) having a viscosity average molecular weight of 55,000 was obtained.

[0177] [Synthesis of resins (PAR-2) to (PAR-16) and (PAR-R1) to (PAR-R4)]

[0178] Resins (PAR-2) to (PAR-16) and (PAR-R1) to (PAR-R4) were synthesized by the same method as the synthesis of resin (PAR-1), except that the molar ratio of bisphenol and dicarboxylic acid and the type of terminal terminator were changed as shown in Table 2. As a result, resins (PAR-2) to (PAR-16) and (PAR-R1) to (PAR-R4) having viscosity average molecular weights as shown in Table 2 were obtained. The viscosity average molecular weight of each resin (PAR) was adjusted by changing the amount of terminal terminator used, and when the viscosity average molecular weight of each resin (PAR) was increased, the amount of terminal terminator used was reduced.

[0179] Table 2

[0180]

[0181] The numerical values ​​for bisphenol shown in Table 2 each represent the molar ratio (percent) relative to the total amount of compound (BP-1) and compound (BP-2). In addition, the numerical values ​​for dicarboxylic acid shown in Table 2 each represent the molar ratio (percent) relative to the total amount of compound (DC-1) and compound (DC-2). In addition, "PFH" represents 1H,1H-perfluoro-1-heptanol. In addition, the molecular weight represents the viscosity average molecular weight.

[0182] (Example 1)

[0183] <Production of electrophotographic photosensitive members>

[0184] [Production of Photosensitive Member 1]

[0185] An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 260.5 mm and a diameter of 30 mm was subjected to cutting processing (JIS B0601: 2014, ten-point average roughness Rzjis: 0.8 μm), and the resultant was used as a conductive support.

[0186] Prepare the following materials.

[0187]

[0188] The above substances were mixed with a rod-shaped sonic oscillator for 20 minutes to provide a dispersion. The dispersion was filtered through a filter with an opening of 5 μm to provide a photosensitive layer coating solution. The photosensitive layer coating solution was applied on a conductive support by a dip coating method and dried with hot air at 120° C. for 50 minutes. Thus, a photosensitive layer (thickness: 30 μm) was formed on the conductive support to provide a photosensitive member 1.

[0189] (Resin Component Analysis of Photosensitive Member 1)

[0190] The high molecular weight components recovered from the obtained photosensitive member are separated in deuterated chloroform. 1 H-NMR spectroscopy analysis 1 H-NMR spectrum. 1 The H-NMR spectrum has peaks at 8.22±0.02ppm, 7.18±0.02ppm, 7.16±0.02ppm, 7.10±0.02ppm, 7.06±0.02ppm, 7.04±0.02ppm, 2.28±0.02ppm, 2.20±0.02ppm, 1.59±0.02ppm and 1.54±0.02ppm. As a result, it was determined that the photosensitive member had structural units represented by formulas (1), (2), (3) and (4). In addition, based on the integration ratio of the above peaks, it can be confirmed that the material amount ratios of the structural units represented by formulas (1), (2), (3) and (4) are as shown in Table 2.

[0191] <Evaluation>

[0192] The sensitivity, image offset and abrasion resistance of the photosensitive member (single-layer type photosensitive member) were evaluated by the following methods.

[0193] A modified device of "ECOSYS P5026cdw" manufactured by KYOCERA Document Solutions Japan Inc. was used as the electrophotographic device. The modified device included a charging roller as a charging device. The charging polarity of the charging roller was positive, and the applied voltage of the charging roller was a DC voltage. In addition, the evaluation machine included a cleaning blade and a charge removing device. The electrophotographic photosensitive member of the drum-in-box unit for this printer was taken out, and the photosensitive member 1 was set instead.

[0194] [Evaluation of sensitivity]

[0195] The surface potential of the photosensitive member irradiated with exposure light after the surface was charged was evaluated as sensitivity (V). Specifically, the sensitivity was evaluated as follows.

[0196] First, the electrophotographic apparatus and the photosensitive member were left to stand under an environment of a temperature of 23° C. and a humidity of 50% RH for 24 hours or more, and then a potential measuring device for the surface of the photosensitive member was mounted on the electrophotographic apparatus.

[0197] The applied voltage was adjusted so that the surface of the photosensitive member reached a predetermined potential (Vd: +700 V). Next, the surface of the photosensitive member was charged and then charged at 0.25 μJ / cm 2 The surface of the photosensitive member was exposed to an exposure amount of . The surface potential at this time was used as the initial sensitivity. The smaller the value, the better the sensitivity. Next, the solid image was output onto 10,000 sheets of paper, and the surface potential was measured in the same manner and used as the sensitivity after durability. The evaluation results are shown in Table 3 (Table 3-1 to Table 3-4).

[0198] <Evaluation of Image Defacement>

[0199] First, the electrophotographic apparatus and the photosensitive member were left to stand under an environment of a temperature of 30° C. and a humidity of 80% RH for 24 hours or more, and then the photosensitive member was mounted on the electrophotographic apparatus.

[0200] Subsequently, an image with an image printing rate of 3% was output onto 30,000 sheets of A4 longitudinal size paper. After that, power supply to the evaluation device was stopped and deactivated for 3 days. After deactivation for 3 days, power supply to the evaluation device was started again, and a character image (E character image) of a repeating grid image and an alphabetical character E (font type: Times, font size: 6 points) was output onto A4 longitudinal size paper. The image defect suppression effect of the resulting images was evaluated separately according to the following evaluation grades. Higher grade numbers indicate more satisfactory effects, and grades 5, 4, and 3 are judged as levels at which image defect suppression effects are obtained. At the same time, grades 1 and 2 are judged as levels at which image defect suppression effects are not obtained. The evaluation results are shown in Table 3.

[0201] Level 5: No image defect is observed in both the lattice image and the E character image.

[0202] Level 4: The grid image is partially blurred, but no image defect is observed in the E character image.

[0203] Level 3: The grid image is partially blurred, and the E character image is partially faded.

[0204] Level 2: The grid image partially disappears, and the E character image completely fades.

[0205] Level 1: The grid image completely disappears, and the E character image completely fades.

[0206] [Evaluation of wear resistance]

[0207] The amount of reduction in thickness (amount of wear) from the initial stage on the surface of the central portion of the photosensitive member 1 used in the evaluation of image stain was measured. In this case, the thickness was measured using a thickness measuring device FISCHER MMS eddy current probe EAW3.3 manufactured by FISCHER INSTRUMENTS KK. The amount of reduction in the thickness of the photosensitive layer was evaluated based on a value obtained by converting the amount of reduction after outputting an image onto 30,000 sheets of paper into the amount of reduction per 1,000 sheets of paper. The evaluation results are shown in Table 3.

[0208] (Examples 2 to 42 and Comparative Examples 1 to 9)

[0209] Electrophotographic photosensitive members were each produced and evaluated in the same manner as in Example 1 except that the kinds and amounts of the binder resin, hole transporting substance, electron transporting substance, charge generating substance and additives mixed in the photosensitive layer coating liquid were changed as shown in Table 3. The results are shown in Table 3.

[0210] The hole transporting substance HR-1 shown in Table 3 is a compound represented by the following formula (HR-1).

[0211]

[0212] Furthermore, the hole transporting substance HR-2 shown in Table 3 is a compound represented by the following formula (HR-2).

[0213]

[0214] Furthermore, the hole transporting substance HR-3 shown in Table 3 is a compound represented by the following formula (HR-3).

[0215]

[0216] Furthermore, the hole transporting substance HR-4 shown in Table 3 is a compound represented by the following formula (HR-4).

[0217]

[0218] Furthermore, the hole transporting substance HR-5 shown in Table 3 is a compound represented by the following formula (HR-5).

[0219]

[0220] Table 3-1

[0221]

[0222] Table 3-2

[0223]

[0224] Table 3-3

[0225]

[0226] Table 3-4

[0227]

[0228] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An electrophotographic photosensitive member comprising: Support body; and Photosensitive layer, wherein the photosensitive layer comprises a binder resin, a charge generating substance, an electron transporting substance and a hole transporting substance, wherein the binder resin comprises a polyarylate resin having a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3), and a structural unit represented by the following formula (4): and The hole transporting substance comprises a compound represented by the following formula (5): In formula (5), R 1 represents an alkyl group having 2 or more and 4 or less carbon atoms, and Ar 1 It represents an aryl group which may have an alkyl group having 1 to 4 carbon atoms as a substituent.

2. The electrophotographic photosensitive member according to claim 1, wherein the ratio of the amount of the structural unit represented by formula (1) relative to the total amount of the structural units derived from dicarboxylic acid used to form the polyarylate resin is 0.30 or more, the amount being calculated in moles.

3. The electrophotographic photosensitive member according to claim 1 or 2, wherein In the polyarylate resin, when the ratio of the amount of the structural unit represented by formula (1) to the total amount of the structural units used to form the polyarylate resin is represented by M1, the ratio of the amount of the structural unit represented by formula (2) to the total amount of the structural units used to form the polyarylate resin is represented by M2, the ratio of the amount of the structural unit represented by formula (3) to the total amount of the structural units used to form the polyarylate resin is represented by M3, and the ratio of the amount of the structural unit represented by formula (4) to the total amount of the structural units used to form the polyarylate resin is represented by M4, M3 / (M1+M3) is 0.30 or more and less than 0.70, and M2 / (M2+M4) is 0.10 or more and less than 0.50, and the amounts are measured in moles. 4 . The electrophotographic photosensitive member according to claim 1 , wherein a ratio of the polyarylate resin relative to the total mass of the binder resin is 50% by mass or more. 5 . The electrophotographic photosensitive member according to claim 1 , wherein the content of the hole transporting substance is 50 parts by mass or more and 90 parts by mass or less relative to 100 parts by mass of the binder resin. 6 . The electrophotographic photosensitive member according to claim 1 , wherein a ratio of the amount of substance of the compound represented by formula (5) relative to the total amount of substance of the hole transporting substance, the amount of substance being calculated in moles, is 0.6 or more.

7. The electrophotographic photosensitive member according to claim 1 or 2, wherein In formula (5), Ar 1 It represents a phenyl group which may have an alkyl group having 1 to 4 carbon atoms as a substituent. 8 . The electrophotographic photosensitive member according to claim 1 , wherein the charge generating substance contains oxytitanium phthalocyanine.

9. The electrophotographic photosensitive member according to claim 1 or 2, wherein the electron transporting substance contains at least one compound selected from the group consisting of: a compound represented by the following formula (6); a compound represented by the following formula (7); a compound represented by the following formula (8); a compound represented by the following formula (9); a compound represented by the following formula (10); a compound represented by the following formula (11); and a compound represented by the following formula (12): Wherein Q in formula (6) 1 and Q 2 , Q in the formula (7) 11 , Q 12 and Q 13 , Q in the formula (8) 21 , Q 22 , Q 23 and Q 24 , Q in the formula (9) 31 and Q 32 , Q in the formula (10) 41 , Q 42 , Q 43 and Q 44 , Q in the formula (11) 51 , Q 52 , Q 53 , Q 54 , Q 55 and Q 56 , and Q in the formula (12) 61 and Q 62 each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom, and Y in the formula (11) 1 and Y 2 Each independently represents an oxygen atom or a sulfur atom.

10. The electrophotographic photosensitive member according to claim 9, wherein the electron transporting substance contains at least one compound selected from the group consisting of: a compound represented by the following formula (E-1); a compound represented by the following formula (E-2); a compound represented by the following formula (E-3); a compound represented by the following formula (E-4); a compound represented by the following formula (E-5); a compound represented by the following formula (E-6); a compound represented by the following formula (E-7); and a compound represented by the following formula (E-8):

11. The electrophotographic photosensitive member according to claim 1 or 2, wherein the photosensitive layer contains as an additive at least one compound selected from the group consisting of: a compound represented by the following formula (T-1); a compound represented by the following formula (T-2); a compound represented by the following formula (T-3); and a compound represented by the following formula (T-4):

12. A process cartridge comprising: The electrophotographic photosensitive member according to any one of claims 1 to 11; and at least one unit selected from the group consisting of a charging unit, a developing unit, and a cleaning unit, The process cartridge integrally supports the electrophotographic photosensitive member and the at least one unit, and is detachably mountable to a main body of the electrophotographic apparatus.

13. A process cartridge according to claim 12, wherein the process cartridge includes the charging unit, and wherein the charging unit is a charging unit configured to positively charge the electrophotographic photosensitive member.

14. An electronic photographic device comprising: The electrophotographic photosensitive member according to any one of claims 1 to 11; Charging unit; Exposure unit; Development unit; and Transfer unit. 15 . The electrophotographic apparatus according to claim 14 , wherein the charging unit is a charging unit configured to positively charge the electrophotographic photosensitive member.

Images