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 desirable to provide an apparatus having high stability in the image 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 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 stability of image quality in 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 also have high stability of image quality.

[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 , R 2 , R 3 and R 4 Each independently represents an alkyl group or an alkoxy group having 1 to 4 carbon atoms.

[0012] In addition, according to another aspect of the present invention, a processing box is provided, which includes: the above-mentioned electronic photographic photosensitive member; and at least one unit selected from the group consisting of a charging unit, a developing unit and a cleaning unit, the processing box integrally supports the electronic photographic photosensitive member and the at least one unit, and can be removably mounted on the main body of the electronic photographic device.

[0013] Furthermore, according to another aspect of the present invention, there is provided an electrophotographic apparatus including: the above-mentioned electrophotographic photosensitive member; a charging unit; an exposure unit; a developing unit; and a transfer unit.

[0014] 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

[0015] Figure 1 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0016] Figure 2 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0017] Figure 3 is a diagram for illustrating an example of the layer constitution of the electrophotographic photosensitive member according to the present invention.

[0018] Figure 4 is a diagram for illustrating an example of a schematic configuration of an electrophotographic apparatus according to the present invention.

[0019] Figure 5 is a diagram for illustrating an example of the configuration of an image forming unit included in the electrophotographic apparatus according to the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in detail below by way of exemplary embodiments.

[0021] In the electrophotographic photosensitive member described in each of Japanese Patent Application Laid-Open Nos. 2022-49733 and 2023-19706, it has been found that image smearing, which is one of image defects, is easily generated during 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.

[0022] Based on the above assumptions, the present inventors have conducted various studies on means for suppressing the occurrence of image offset 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.

[0023] 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).

[0024]

[0025] Furthermore, the hole transporting substance includes a compound represented by the following formula (5):

[0026]

[0027] In formula (5), R 1 , R 2 , R 3 and R 4 Each independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0028] The present inventors have found that when the electrophotographic photosensitive member has the above-described constitution according to the present invention, during repeated use, the occurrence of image offset can be suppressed while achieving high durability.

[0029] The inventors speculate that the reasons for the foregoing 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 a hole transporting substance having a large molecular weight and a rigid skeleton having high hole transport performance. However, the hole transporting substance represented by formula (5) has a relatively soft skeleton while having a large molecular weight, and therefore has high compatibility with the polyarylate resin. When the polyarylate resin and the hole transporting substance cannot be satisfactorily mixed with each other due to low compatibility, uneven concentration of the hole transporting substance occurs on the surface of the photosensitive member, causing uneven micro electrical resistance. Then, the local large current caused by the uneven discharge generates discharge products, thereby causing image smearing. By using the hole transporting substance represented by formula (5), the resistance unevenness is eliminated and the generation of discharge products can be suppressed, so the occurrence of image smearing can be suppressed.

[0030] The constitution of the electrophotographic photosensitive member according to the present invention is described below in more detail.

[0031] [Electrophotographic photosensitive member]

[0032] The electrophotographic photosensitive member according to the present invention includes a support and a photosensitive layer formed on the support.

[0033] 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.

[0034] (Single-layer type photosensitive member)

[0035] Refer to the following Figures 1 to 3 A single-layer type photosensitive member 1 according to one 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 .

[0036] like Figure 1 As 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 photosensitive layer composed of a single layer (one layer). The photosensitive layer 3 includes a binder resin, a charge generating substance, an electron transporting substance, and a hole transporting substance.

[0037] like Figure 2As 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 may be Figure 1 As shown, it can be formed directly on the support 2, or it can be formed as shown. Figure 2 The substrate is shown to be formed on the support 2 via the primer layer 4 .

[0038] 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.

[0039] 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.

[0040] <Support>

[0041] 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.

[0042] As a material for the support, metal, resin, glass or the like is preferable.

[0043] 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.

[0044] Furthermore, conductivity may be imparted to the resin or glass through a treatment involving, for example, mixing the resin or glass with a conductive substance or coating the resin or glass with a conductive substance.

[0045] <Base Coating>

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] In addition, the undercoat layer may further contain additives.

[0054] 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.

[0055] 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.

[0056] <Single-layer photosensitive layer>

[0057] 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.

[0058] 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.

[0059] [Binder resin]

[0060] 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).

[0061]

[0062] The above-mentioned polyarylate resin may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer or a block copolymer.

[0063] 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 greater than 0.30, and more preferably greater than 0.55.

[0064] 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.

[0065] Furthermore, from the viewpoint of suppressing an increase in residual potential, M3 / (M1+M3) is preferably 0.30 or more and less than 0.70.

[0066] Furthermore, from the viewpoint of improving solubility in a solvent, M4 / (M2+M4) is preferably less than 0.90.

[0067] 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 0.50 or more.

[0068] 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.

[0069] 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 preferably 0.30 or more, more preferably 0.50 or more.

[0070] 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.

[0071] 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.

[0072] 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.

[0073]

[0074] 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.

[0075]

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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-mentioned (hereinafter sometimes referred to as "other binder resin").

[0080] 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).

[0081] The structure of the polyarylate resin of the present invention can be obtained by using 1 The composition of the polymer components recovered from the photosensitive layer was analyzed by H-NMR spectroscopy. 1 determined by H-NMR spectroscopy.

[0082] 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.

[0083] (Reprecipitation of resin in photosensitive layer)

[0084] 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.

[0085] • Wipe the inner surface of the cut 10 cm cylinder with lens cleaning paper soaked in chloroform.

[0086] 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.)

[0087] The chloroform solution containing the photosensitive layer was concentrated to 2 mL using a rotary evaporator, and the concentration was stopped. 50 mL of a methanol / acetone mixed solution (volume ratio of 1:1) was prepared, and the entire amount of the concentrated solution was added dropwise thereto while stirring the mixed solution, thereby performing reprecipitation.

[0088] Suction filtration was performed using a funnel (funnel: SU-40, filter paper: No. 5C-40, manufactured by Kiriyama Glass Co.).

[0089] The residue on the filter paper was recovered with a scraper and dried in vacuum (70°C, 1 hour).

[0090] (NMR measurement)

[0091] 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.

[0092] (Deuterated chloroform: manufactured by Sigma-Aldrich Japan GK, chloroform-d, model: 612200) (NMR tube: manufactured by Norell, Inc., ST500-7, model: S3010)

[0093] • Perform NMR measurements.

[0094] Equipment: AVANCE 500 manufactured by Bruker

[0095] Conditions: Proton NMR, automated measurement by Icon-NMR

[0096] Scan times: 32

[0097] Reference peak: The methyl peak of tetramethylsilane was set to 0 ppm.

[0098] [Hole transport substances]

[0099] The hole transporting substance includes a compound represented by the following formula (5).

[0100]

[0101] In formula (5), R 1 , R 2 , R 3 and R 4 Each independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0102] Preferably, in formula (5), R 2 and R 4 The substitution positions of are each 6-position. In addition, it is preferred that in formula (5), R 1 and R 3 represent the same groups, and R 2 and R 4 represent groups that are identical to each other.

[0103] By R 1 , R 2 , R 3 and R 4Examples of the alkyl group represented by each of include alkyl groups each having a carbon atom number of 1 or more and 4 or less, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0104] In the compound represented by formula (5), there are cis isomers and trans isomers. Among them, the trans isomer is preferably used.

[0105] Suitable examples of the compound represented by formula (5) include the compounds shown in Table 1. Examples of the compound represented by formula (5) shown in Table 1 are sometimes referred to as "hole transport substances (H-1) to (H-10)" below. Hole transport substances (H-1) to (H-10) are each a trans isomer.

[0106] 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 confirmed.

[0107] Table 1

[0108] The compound represented by formula (5) <![CDATA[R 1 ]]> <![CDATA[R 2 ]]> <![CDATA[R 3 ]]> <![CDATA[R 4 ]]> H-1 Me 6-Et Me 6-Et H-2 Et 6-Et Et 6-Et H-3 i-Pr 6-i-Pr i-Pr 6-i-Pr H-4 Me 6-t-Bu Me 6-t-Bu H-5 Me 6-OMe Me 6-OMe H-6 OMe 6-OMe OMe 6-OMe H-7 Me 4-OMe Me 4-OMe H-8 OE 6-OEt OE 6-OMe H-9 Me 6-Et Et 6-Et H-10 Me 6-Et i-Pr 6-i-Pr

[0109] In Table 1, Me represents a methyl group, Et represents an ethyl group, i-Pr represents an isopropyl group, t-Bu represents a tert-butyl group, OMe represents a methoxy group, and OEt represents an ethoxy group.

[0110] In addition, in Table 1, R 2 and R 4 The digital representation of the structure of formula (5) is 2 and R 4 replacement position.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] It is preferred that the ratio of the content of the compound represented by formula (5) in the photosensitive layer to the content of all hole transport substances in the photosensitive layer is 50% by mass or more.

[0115] [Charge generating material]

[0116] 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.

[0117] 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).

[0118]

[0119] Phthalocyanine pigments may be crystalline or amorphous. 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).

[0120] For example, in a digital optical image forming apparatus (e.g., a laser beam printer or a facsimile 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, more preferably a metal-free phthalocyanine or an oxytitanium phthalocyanine, because these substances each have a high quantum yield in a wavelength region of 700 nm or more. Furthermore, the charge generating substance is still more preferably an oxytitanium phthalocyanine, and particularly preferably a Y-type oxytitanium phthalocyanine.

[0121] 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.

[0122] 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.

[0123] 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 5 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0124] [Electron transport substances]

[0125] 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.

[0126]

[0127]

[0128] 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 Q 24 , 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.

[0129] Preferably, Q in formula (6) 1 and Q 2 , Q in formula (7) 11 To Q 13 , Q in formula (8) 21 To Q24 , 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.

[0130] 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 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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)" below, respectively.

[0137]

[0138]

[0139]

[0140] 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.

[0141] [additive]

[0142] The photosensitive layer may include additives as required. 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.

[0143] 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.

[0144]

[0145]

[0146] Next, a process cartridge and an electrophotographic apparatus according to the present invention are described.

[0147] 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.

[0148] 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.

[0149] The charging unit may be a charging unit configured to positively charge the electrophotographic photosensitive member.

[0150] [Electronic photography equipment]

[0151] An example of the constitution of an electrophotographic apparatus including the process cartridge according to the present invention is described in detail below.

[0152] Figure 4 is a schematic diagram for illustrating an example of the configuration of the electrophotographic apparatus according to the present invention. Figure 5 It is used to show Figure 4 Schematic diagram of an example of the configuration of an image forming unit included in the electrophotographic apparatus shown in FIG.

[0153] In the electrophotographic apparatus 400, as Figure 4As shown, image forming units A, B, C, and D each including a photosensitive member 407 are arranged in series. The image forming units A, B, C, and D each include a photosensitive member 407, a charging device 402, and a developing device 406, and the electrophotographic apparatus 400 is configured to form an image by superimposing a toner image formed on each photosensitive member 407 on a transfer material such as paper.

[0154] The toners used in the respective image forming units A, B, C, and D are toners corresponding to yellow, magenta, cyan, and black, respectively, and the toner images formed by the respective image forming units are superimposed to form a full-color image.

[0155] The transfer material is picked up from the transfer material box 410 by the pickup roller 413, conveyed by the conveying roller 414, adjusted in position by the registration roller 415, and adsorbed onto the transfer material conveying and transfer belt 416. Thereafter, the images sequentially formed by the respective image forming units A, B, C, and D are transferred onto the transfer material, and the toner images transferred onto the transfer material are each fixed by the fixing device 412. In addition, the toner, paper powder, etc. on the transfer material conveying and transfer belt 416 are cleaned by the belt cleaning device 411.

[0156] Each of the image forming units A, B, C, and D includes a photosensitive member 407, a charging device 402, an exposure device 401, a developing device 406, and a transfer device 408. In each of the image forming units A, B, C, and D, the charging device 402 charges the photosensitive member 407, and the exposure device 401 exposes the charged photosensitive member 407 to exposure light 404 to form an electrostatic latent image. In addition, the developing device 406 develops the electrostatic latent image with a toner, and the transfer device 408 transfers the toner image onto a transfer material.

[0157] The toner supply device 405 is provided on the developing device 406. Furthermore, a cleaning device 409 for removing residual toner from the surface of the photosensitive member 407 after transfer and a pre-exposure device 403 are provided around the photosensitive member 407.

[0158] The process cartridge 500 , which is configured to be detachably mounted to the main body of the electrophotographic apparatus 400 , integrally supports the photosensitive member 407 , the charging device 402 , the developing device 406 , and the cleaning device 409 .

[0159] The transfer device 408 preferably includes a contact transfer unit. A belt, a roller or a drum is preferably used as the contact transfer unit.

[0160] exist Figure 4, an example of a configuration in which an image is directly transferred onto a transfer material conveyed by a transfer material conveyor and a transfer belt 416 by using a transfer device 408 is shown, but a configuration in which an image is first transferred onto an intermediate transfer member and then transferred from the intermediate transfer member onto a transfer material may be adopted.

[0161] In the cleaning device 409, a scraper cleaning, a roller cleaning, a brush cleaning, a magnetic roller cleaning, etc. are used. In particular, as Figure 5 As shown, it is suitable for cleaning with a scraper. Figure 5 In the example shown, a cleaning blade 501 is used, and the scraped toner is stored. From the viewpoint of preventing the surface of the photosensitive member from being scratched, a cleaner-less configuration is preferred.

[0162] As the exposure device 401 for forming an electrostatic latent image, a known unit such as a device that emits laser light as the exposure light 404 or a device including a light emitting diode (LED) as a light source is used.

[0163] The photosensitive member 407 is the above-described electrophotographic photosensitive member according to the present invention.

[0164] The charging device 402 includes a corona charging member 508. The corona charging member 508 charges the photosensitive member 407 without contacting the photosensitive member 407, such as Figure 5 As shown in detail.

[0165] The corona charging member 508 includes a charging control unit 510 that controls the charging potential and a discharge electrode 509 .

[0166] As the discharge electrode 509 of the corona charging member 508, a metal wire having a diameter of preferably 10 μm to 500 μm, more preferably 50 μm to 200 μm is preferably used. As the material of the metal wire, tungsten or stainless steel coated with a noble metal such as gold as required is used. In addition, as the discharge electrode 509, a needle-shaped discharge electrode can be used.

[0167] When a metal wire or needle-like electrode is used as the discharge electrode 509, a charging control unit 510 is provided between the discharge electrode 509 and the photosensitive member 407. When the charging control unit 510 is provided, the charged potential of the photosensitive member 407 can be set to a desired potential.

[0168] In a scorotron charger, a grid wire or the like to which a voltage is applied is used as the charging control unit 510. In addition, a unit having a configuration in which a metal thin plate such as stainless steel (SUS) is etched to allow ions to flow therethrough may be preferably used as the charging control unit 510 instead of the grid wire.

[0169] Meanwhile, in the case of a corotron charger, the charging potential is controlled by the amount of current, but the charging potential obtained by the corotron charger has environmental dependence. In view of the above, when pursuing high image quality, the charging potential cannot be sufficiently controlled in the corotron charger in some cases, so it is preferable to use a grid electrode charger.

[0170] Figure 4 4 is an example of a full-color printer, but the electronic photographic device according to the present invention is not limited thereto. For example, the electronic photographic device according to the present invention may be a monochrome printer. In addition, the electronic photographic device according to the present invention is not limited to a printer, and may be, for example, a copier or a multi-function peripheral device.

[0171] According to the present invention, an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus having high durability and having high stability of image quality when repeatedly used can be provided.

[0172] [Example]

[0173] 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.

[0174] <Production of Polyarylate Resin (PAR)>

[0175] [Synthesis of resin (PAR-1)]

[0176] A three-necked flask including a thermometer, a three-way stopcock and a dropping funnel was used as a reaction vessel.

[0177] First, prepare the following materials.

[0178] ·Compound (BP-2) as a monomer (28.7 mmol)

[0179] ·Compound (BP-1) as a monomer (12.3 mmol)

[0180] · 2,6-Dimethylphenol (DMP) as an end terminator (0.413 mmol)

[0181] Sodium hydroxide (98 mmol)

[0182] Benzyltributylammonium chloride (0.384 mmol)

[0183] 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.

[0184] 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.

[0185] 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.

[0186] [Synthesis of resins (PAR-2) to (PAR-16) and (PAR-R1) to (PAR-R4)]

[0187] 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.

[0188] Table 2

[0189]

[0190] 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.

[0191] (Example 1)

[0192] <Production of electrophotographic photosensitive members>

[0193] [Production of Photosensitive Member 1]

[0194] 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.

[0195] Prepare the following materials.

[0196]

[0197] 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.

[0198] (Resin Component Analysis of Photosensitive Member 1)

[0199] 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. 1The 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.

[0200] <Evaluation>

[0201] The photosensitive member (single-layer type photosensitive member) was evaluated for image offset by the following method.

[0202] A remodeled device obtained by remodeling a monochrome laser printer (product name: HL-5200, manufactured by Brother Industries, Ltd.) was used as the electrophotographic device. A high-voltage power supply control system (product name: Model 615-3, manufactured by Trek Japan) was used as a power source for supplying power to a corona charger from the outside of the printer. The electrophotographic photosensitive member of the drum-in-box unit for this printer was taken out, and the photosensitive member 1 was set instead.

[0203] <Evaluation of Image Defacement>

[0204] First, the electrophotographic apparatus and the photosensitive member were placed 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.

[0205] The amount of current flowing through the corona wire of the corona charger was adjusted to 500 μA, and an image with an image printing rate of 3% was output onto 30,000 sheets of A4 longitudinal size paper. After that, the power supply to the electrophotographic device was stopped and it was deactivated for 3 days. After being deactivated for 3 days, the power supply to the electrophotographic 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 Tables 3-1, 3-2, 3-3, and 3-4.

[0206] Level 5: No image defect is observed in both the lattice image and the E character image.

[0207] Level 4: The grid image is partially blurred, but no image defect is observed in the E character image.

[0208] Level 3: The grid image is partially blurred, and the E character image is partially faded.

[0209] Level 2: The grid image partially disappears, and the E character image completely fades.

[0210] Level 1: The grid image completely disappears, and the E character image completely fades.

[0211] [Evaluation of wear resistance]

[0212] 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 Tables 3-1, 3-2, 3-3, and 3-4.

[0213] (Examples 2 to 32 and Comparative Examples 1 to 7)

[0214] Electrophotographic photosensitive members were produced and evaluated in the same manner as in Example 1, respectively, 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 solution were changed as shown in Table 3-1, Table 3-2, Table 3-3 and Table 3-4. The results are shown in Table 3-1, Table 3-2, Table 3-3 and Table 3-4.

[0215] The hole transporting substance HR-1 shown in Table 3-1, Table 3-2, Table 3-3, and Table 3-4 is a compound represented by the following formula (HR-1).

[0216]

[0217] Furthermore, the hole transporting substance HR-2 shown in Table 3-1, Table 3-2, Table 3-3, and Table 3-4 is a compound represented by the following formula (HR-2).

[0218]

[0219] Furthermore, the hole transporting substance HR-3 shown in Table 3-1, Table 3-2, Table 3-3, and Table 3-4 is a compound represented by the following formula (HR-3).

[0220]

[0221] Table 3-1

[0222]

[0223] Table 3-2

[0224]

[0225] Table 3-3

[0226]

[0227] Table 3-4

[0228]

[0229] 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 , R 2 , R 3 and R 4 Each independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

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 the formula (5), R 1 and R 3 represent groups that are identical to each other, and R 2 and R 4 represent groups that are identical to each other.

8. The electrophotographic photosensitive member according to claim 1 or 2, wherein In the formula (5), R 2 and R 4 The substitution position of each is the 6-position.

9. The electrophotographic photosensitive member according to claim 1 or 2, wherein the electron transporting substance comprises 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 comprises 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