Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus

Abstract

To provide an electrophotographic photoreceptor having excellent wear resistance and a surface layer that suppresses image blurring. [Solution] An electrophotographic photoreceptor having a surface layer containing a polymer of a polymerizable charge-transporting compound, wherein in kinematic viscoelasticity measurements, the relationship between the storage modulus G' and the loss modulus G'' of the surface layer is G'>G'' at room temperature, and the Tanδ peak top is in the temperature range of 85°C to 100°C.

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic photoreceptor, a process cartridge, and an electrophotographic apparatus.

Background Art

[0002] An organic electrophotographic photoreceptor (hereinafter referred to as "electrophotographic photoreceptor") mounted in an electrophotographic apparatus is required to achieve both improvement in mechanical durability (abrasion resistance) and suppression of image flow that causes image quality defects for the purpose of extending the service life and improving the image quality during repeated use.

[0003] As a technique for improving the abrasion resistance of an electrophotographic photoreceptor, there is a method of containing a thiol compound in the surface layer of the electrophotographic photoreceptor to improve the mechanical strength and flexibility of the surface layer. In Patent Document 1, a technique is disclosed in which the mechanical strength is improved and flexibility and toughness are imparted by including a compound having four or more primary thiol groups and a compound having two or more secondary thiol groups in the surface layer.

[0004] Also, as a technique for suppressing image flow, there is a method of making the chain polymerizable functional group of the resin used in the surface layer of the electrophotographic photoreceptor a methacryloyl group. In Patent Document 2, a technique is disclosed in which a surface layer composed of a compound having a methacryloyl group as the chain polymerizable functional group and having two functional groups provides excellent potential stability during repeated use of the photoreceptor and suppresses image flow.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technology disclosed in Patent Document 1, further improvement in abrasion resistance was required to meet the demand for higher durability. In addition, in the technology disclosed in Patent Document 2, while a surface layer capable of suppressing image flow could be obtained, the abrasion resistance might deteriorate. Therefore, there was room for improvement in achieving both high abrasion resistance and suppression of image flow in the electrophotographic photoreceptor.

[0007] One aspect of the present disclosure aims to provide an electrophotographic photoreceptor having high abrasion resistance and suppressed image flow. Another aspect of the present disclosure aims to provide a process cartridge equipped with the electrophotographic photoreceptor and an electrophotographic apparatus equipped with the process cartridge.

Means for Solving the Problems

[0008] According to one aspect of the present disclosure, the electrophotographic photoreceptor according to the present disclosure has a surface layer containing a polymer of at least one polymerizable charge transporting compound selected from the group consisting of the compound represented by formula (CT-1) and the compound represented by formula (CT-2), and in the dynamic viscoelasticity measurement, the relationship between the storage modulus G' and the loss modulus G'' is G' > G'' at room temperature, and it has a peak top of Tanδ in the temperature range of 85°C or higher and 100°C or lower.

Chemical Formula

Chemical Formula

[0009] Furthermore, the electrophotographic photoreceptor has a storage modulus G' of 1000 Pa or more and a loss modulus G'' of 1000 Pa or more.

[0010] Furthermore, the surface layer contains polymers of a composition containing the polymerizable charge transport compound and the thiol compound, The electrophotographic photoreceptor is characterized in that when the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the composition is denoted as WCT, and the content of the thiol compound is denoted as WT, WCT and WT satisfy formula (1). 0.01 ≤ WT / WCT ≤ 0.07 (1)

[0011] Furthermore, the electrophotographic photoreceptor is a compound represented by formula (T-1) in which the thiol compound is expressed. [ka] (In formula (T-1), Y represents a carbon atom or a heterocycle with 2 or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with 1 to 3 carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.) [Effects of the Invention]

[0012] According to one aspect of this disclosure, an electrophotographic photoreceptor is provided that has high wear resistance and suppresses image flow. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of the configuration of the electrophotographic photoreceptor described herein. [Figure 2] This figure shows an example of a polishing machine using abrasive sheets. [Figure 3] This figure shows an example of a schematic configuration of a process cartridge equipped with the electrophotographic photoreceptor of this disclosure, and an electrophotographic apparatus equipped with the process cartridge. [Figure 4] This is a schematic diagram showing an example of a process cartridge having an electrophotographic photoreceptor according to the present disclosure. [Figure 5] This is a schematic diagram showing an example of an electrophotographic apparatus having an electrophotographic photoreceptor according to the present disclosure. [Modes for carrying out the invention]

[0014] In this disclosure, unless otherwise specified, the expressions "XX or greater and YY or less" or "XX to YY" that represent a numerical range mean a numerical range that includes the lower and upper limits. Furthermore, when a numerical range is described in steps, the upper and lower limits of each numerical range can be combined in any way. The present disclosure will be described in detail below with reference to preferred embodiments. As a result of the studies by the present inventors, an electrophotographic photoreceptor has a surface layer containing a polymer of at least one polymerizable charge transport compound selected from the group consisting of the compound represented by formula (CT-1) and the compound represented by formula (CT-2), and in the dynamic viscoelasticity measurement, the relationship between the storage elastic modulus G' and the loss elastic modulus G" of the surface layer is G' > G" at room temperature, and it has a peak top of Tanδ in the temperature range of 85°C or higher and 100°C or lower, so that an electrophotographic photoreceptor having high wear resistance and suppressed image flow has been found.

Chemical formula

Chemical formula

Chemical formula

[0015] The inventors speculate that the electrophotographic photoreceptor described herein exhibits excellent wear resistance and superior image blur suppression as follows: Electrophotographic photoreceptors having a surface layer containing a charge-transporting compound whose polymerizable functional group is an acrylic group tend to exhibit image blurring. This is thought to be because when the acrylic group is subjected to discharge, it interacts with oxygen and water in the atmosphere to form oxalic acid-derived discharge products, which accumulate on the drum surface. This reduces the drum's surface resistance, making image blurring more likely.

[0016] As a result of our investigations, we found that image blurring can be suppressed by incorporating polymers of charge-transporting compounds, represented by formulas (CT-1) and (CT-2), in the surface layer, where the polymerizable functional group is a methacryloyl group. It is believed that because the C=C double bond portion of the methacryloyl group is protected by a methyl group, even when subjected to discharge degradation, interaction with oxygen and water in the atmosphere is less likely to occur, thereby suppressing the generation of discharge products derived from oxalic acid and thus suppressing image blurring. However, the surface layer having polymers of charge-transporting compounds with a polymerizable functional group of a methacryloyl group has lower abrasion resistance than the surface layer with an acrylic group polymerizable functional group, so there was room for improvement.

[0017] As a result of further investigation by the present inventors, it was found that an electrophotographic photoreceptor with excellent surface abrasion resistance can be obtained by adjusting the peak top of Tanδ in a temperature range of 85°C to 100°C, where the storage modulus (G') > loss modulus (G") of the surface layer is measured at room temperature in kinematic viscoelasticity measurements.

[0018] The Tanδ peak top temperature, obtained in dynamic viscoelasticity measurements, is the temperature at which molecular chain motion begins to become active, and at which molecular stretching and rotational motion within the molecular chains increases. When molecular stretching and rotational motion within the molecular chains increases, internal stress can be dispersed. Therefore, if the surface layer has a storage modulus (G') > loss modulus (G") at room temperature, and the Tanδ peak top temperature is within the temperature range generated by the frictional heat temperature of the nip section, i.e., between 85°C and 100°C, the pressure applied from the blade to the electrophotographic photoreceptor can be dispersed most effectively, and wear can be suppressed. One method for achieving the above range in dynamic viscoelasticity measurements is to use Ar in equation (CT-1). 11 ~Ar 13 Methods for adjusting the total number of carbon atoms in the alkyl and alkylene groups contained in the substituted aryl group shown, methods for incorporating a polymer of a composition containing the thiol compound shown in formula (T-1) into the surface layer, and combinations thereof are examples.

[0019] For example, in this disclosure, in formula (CT-1), Ar 11 ~Ar 13 Each of these independently represents a substituted or unsubstituted aryl group, of which at least one has a monovalent functional group represented by formula (P-1). The alkylene group Z in formula (P-1) 11 The flexibility of the alkyl chain can be adjusted by adjusting the total number of carbon atoms in each alkyl group contained in the aryl group other than formula (P-1). In kinematic viscoelasticity measurements, in order to adjust so that the storage modulus (G') > loss modulus (G") at room temperature and the Tanδ peak top is in the temperature range of 85°C to 100°C, it is preferable to set the total number of carbon atoms to 2 or more and 15 or less. By setting the total number of carbon atoms to the above range, the pressure applied from the blade to the electrophotographic photoreceptor can be best dispersed by the flexibility of the alkyl chain, the amount of wear is suppressed, and an electrophotographic photoreceptor with high wear resistance and suppressed image flow can be obtained.

[0020] Furthermore, in this disclosure, it is preferable to include a polymer of a composition containing the thiol compound represented by formula (T-1) in the surface layer. When a polymer of a composition containing the thiol compound represented by formula (T-1) is included in the surface layer, the polymerizable functional group of the charge transport compound and the thiol compound undergo an enthiol reaction, forming CS bonds in the cured film which is the surface layer. Since CS bonds have lower bond energy than CC bonds, their intramolecular stability is reduced, and the Tanδ peak top can be adjusted. Specifically, when the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the surface layer composition is WCT, and the content of the thiol compound is WT, then WCT and WT are of formula (1) 0.01 ≤ WT / WCT ≤ 0.07 (1) By incorporating the material to satisfy the specified conditions, the Tanδ peak top temperature can be adjusted to a range of 85°C to 100°C. This allows for the most even distribution of pressure from the blade to the electrophotographic photoreceptor, thus reducing wear. If WT / WCT is less than 0.01, the Tanδ peak top temperature is higher than the nip friction heat temperature, suggesting that molecular motion is sluggish at the nip friction heat temperature. Consequently, the pressure from the blade to the electrophotographic photoreceptor is not evenly distributed, leading to cracking of the surface layer and increased wear. If WT / WCT is greater than 0.07, the Tanδ peak top temperature is lower than the nip friction heat temperature, suggesting that molecular motion becomes more active at the nip friction heat temperature. This molecular motion is not limited to intramolecular stretching and rotation, but the entire molecular chain begins to move, resulting in fluidity. Increased fluidity leads to greater deformation of the surface layer, which is thought to increase wear. Therefore, when the thiol compound represented by formula (T-1) is included in such a way that formula (1) is satisfied, an electrophotographic photoreceptor with high wear resistance and suppressed image blurring can be obtained. [ka] (In formula (T-1), Y represents a carbon atom or a heterocycle with 2 or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with 1 to 3 carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.)

[0021] The relationship between the storage modulus G' and the loss modulus G'' of the surface layer is G' > G'' at room temperature. Furthermore, it is preferable that the storage modulus G' is 1000 Pa or more and the loss modulus G'' is 1000 Pa or more. It is even more preferable that both the storage modulus G' and the loss modulus G'' are 10000 Pa or more.

[0022] <Charge-transporting compounds represented by formula (CT-1)> In the surface layer of the electrophotographic photoreceptor of this disclosure, when forming the surface layer of the electrophotographic photoreceptor, only one compound represented by formula (CT-1) may be used, or two or more compounds may be used in combination. The following are specific examples of compounds represented by formula (CT-1) of this disclosure, but this disclosure is not limited to these. [ka]

[0023] <Charge-transporting compounds represented by formula (CT-2)> In the surface layer of the electrophotographic photoreceptor of this disclosure, when forming the surface layer of the electrophotographic photoreceptor, one compound represented by formula (CT-2) may be used alone, or two compounds may be used in combination. The following are specific examples of compounds represented by formula (CT-2) of this disclosure, but this disclosure is not limited to these. [ka]

[0024] <Measurement of Tanδ peak top temperature in kinematic viscoelasticity measurements> In the embodiments of this disclosure, the storage modulus, Tanδ, of the surface layer of the electrophotographic photoreceptor was measured using a rotating plate rheometer "ARES" (manufactured by TA INSTRUMENTS). The surface layer of the electrophotographic photoreceptor was scraped off with a razor blade, and the back surface of the scraped film was rubbed with a cotton swab soaked in xylene to obtain a sample of the surface layer alone, which was then used for measurement. The measurement was performed under the following conditions. (1) Use a parallel plate with a diameter of 7.9 mm. (2) The frequency shall be 6.28 rad / sec (1.0 Hz). (3) Set the initial applied strain value (Strain) to 0.1%. (4) Measurements will be taken between 30°C and 200°C at a heating rate (Ramp Rate) of 2.0°C / min. The measurements will be taken using the following automatic adjustment mode settings: Measurements will be taken in automatic strain adjustment mode (Auto Strain). (5) Set Max Applied Strain to 20.0%. (6) The maximum torque (Max Allowed Torque) is set to 200.0 g·cm, and the minimum torque (Min Allowed Torque) is set to 0.2 g·cm. (7) Set the Strain Adjustment to 20.0% of Current Strain. For measurement, use the Auto Tension mode. (8) Set Auto Tension Direction to Compression. (9) Set the initial static force to 10.0g and the auto tension sensitivity to 40.0g. (10) The operating conditions for Auto Tension are: Sample Modulus is 1.0 × 10 3 It is Pa or higher.

[0025] <Thiol compounds represented by formula (T-1)> In the surface layer of the electrophotographic photoreceptor of this disclosure, when forming the surface layer of the electrophotographic photoreceptor, one thiol compound represented by formula (T-1) may be used, or two or more may be used in combination. Suitable thiol compounds to use include Karenz MT® BD1 (1,4-bis(3-mercaptobutyryloxy)butane, manufactured by Resonaq Corporation, a compound containing two secondary thiol groups), Karenz MT NR1 (1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by Resonaq Corporation, a compound containing three secondary thiol groups), or Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups).

[0026] From the viewpoint of wear resistance, the content of the thiol compound represented by formula (T-1) contained in the surface layer of the electrophotographic photoreceptor of this disclosure is preferably such that WT / WCT is 0.01 or more and 0.03 or less, and particularly preferably 0.02, where WCT is the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the composition and WT is the content of the thiol compound.

[0027] Furthermore, the molecular weight of the thiol compound represented by formula (T-1) is preferably 250 to 600, and more preferably 260 to 570.

[0028] <Measurement of remaining thiol compounds> The residual rate of the thiol compound contained in the surface layer of the electrophotographic photoreceptor of this disclosure was evaluated as follows. For electrophotographic photoreceptors, the surface layer was scraped off at a position 179 mm from the top edge of the photoreceptor using a razor blade. Infrared absorption measurements were performed on the surface layer fragment using Fourier transform infrared spectroscopy total internal reflection, and the IR peak ratio of residues of thiol compounds (SH groups) that did not contribute to the polymerization reaction was calculated. A Perkin Elmer Instruments Spectrum One FT-IR Spectrometer was used for the Fourier transform infrared spectroscopy, and measurements were performed using a Ge prism and a KRS-5 prism, respectively. The 2550-2600 cm⁻¹ range originated from the thiol compounds. -1 The absorbance of the SH stretch absorber exhibiting infrared absorption spectra in the range is denoted as AT, and the absorbance derived from the thiol compound is 1735-1750 cm⁻¹. -1 When the absorbance of the C=O stretchable absorber of the ester group exhibiting an infrared absorption spectrum in the specified range is denoted as AE, it is preferable that AT / AE is 0.001 or less.

[0029] For example, 2550-2600 cm³ derived from thiol compounds such as Karenz MT BD1, Karenz MT NR1, or Karenz MT PE1 -1 The absorbance of the SH stretch absorber of a thiol compound exhibiting an infrared absorption spectrum in the range is defined as AT, and the absorbance from Karenz MT BD1, Karenz MT NR1, or Karenz MT PE1 is 1735-1750 cm⁻¹. -1 When the absorbance of the C=O stretchable absorber of the ester group of a thiol compound exhibiting an infrared absorption spectrum in the specified range is denoted as AE, it is preferable that AT / AE is 0.001 or less.

[0030] <Electrophotographic photoconductor> Figure 1 shows an example of the layer structure of the electrophotographic photoreceptor of this disclosure. In Figure 1, a base layer 102, a charge generation layer 103, a charge transport layer 104, and a protective layer 105 are laminated on a support 101. The photosensitive layer, which will be described later, may be composed of a laminated photosensitive layer having a charge generation layer and a charge transport layer, or it may be composed of a single-layer photosensitive layer containing a charge generation material and a charge transport material.

[0031] Methods for applying the coating solution to each layer include immersion coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, immersion coating is preferred from the viewpoint of efficiency and productivity.

[0032] The configuration of the electrophotographic photoreceptor described herein will be explained below. <Support> The support for the electrophotographic photoreceptor is preferably conductive (a conductive support). The support can take various shapes, such as cylindrical, belt-shaped, or sheet-shaped. A cylindrical support is preferred. The surface of the support may also be subjected to electrochemical treatments such as anodizing, blasting, or cutting. Suitable materials for the support include metal, resin, and glass. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support made of aluminum is preferred. Furthermore, it is preferable to impart conductivity to resins and glass by processing them, such as by mixing or coating them with conductive materials.

[0033] <Conductive layer> Although not shown in Figure 1, a conductive layer may be provided on the support. By providing a conductive layer, scratches and irregularities on the surface of the support can be concealed, and light reflection on the surface of the support can be controlled. The conductive layer preferably contains conductive particles and a resin. Examples of materials for conductive particles include metal oxides, metals, and carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, and bismuth oxide. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, it is preferable to use metal oxide particles as conductive particles, and it is more preferable to use titanium oxide particles, tin oxide particles, or zinc oxide particles. When using metal oxide particles as conductive particles, the surface of the metal oxide particles may be treated with a silane coupling agent or the like, or the metal oxide particles may be doped with elements such as phosphorus or aluminum, or their oxides.

[0034] Furthermore, the conductive particles may have a laminated structure comprising core material particles and a coating layer covering those particles. Examples of core material particles include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of coating layer particles include metal oxide particles such as tin oxide. Furthermore, when metal oxide particles are used as conductive particles, their volume-average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less. Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, and alkyd resin.

[0035] Furthermore, the conductive layer may further contain silicone oil, resin particles, a concealing agent such as titanium dioxide, etc. A conductive layer can be formed by preparing a coating solution for a conductive layer containing the above-mentioned materials and solvents, forming this coating film on a support, and drying it. Examples of solvents used in the coating solution for a conductive layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Methods for dispersing conductive particles in the coating solution for a conductive layer include using a paint shaker, sand mill, ball mill, or liquid impact type high-speed disperser. The thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0036] <Underlayer> In this disclosure, an undercoat layer may be provided on the support or conductive layer. Providing an undercoat layer enhances the interlayer adhesion function and imparts a charge injection blocking function. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having polymerizable functional groups.

[0037] Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamide-imide resin, and cellulose resin. Polymerizable functional groups found in monomers possessing polymerizable functional groups include isocyanate groups, blocked isocyanate groups, methylol groups, alkylated methylol groups, epoxy groups, metal alkoxide groups, hydroxyl groups, amino groups, carboxyl groups, thiol groups, carboxylic acid anhydride groups, and carbon-carbon double bond groups.

[0038] Furthermore, the undercoat layer may further contain electron transport materials, metal oxide particles, metal particles, conductive polymers, etc., for the purpose of improving electrical properties. Among these, electron transport materials and metal oxide particles are preferred. Examples of electron transport materials include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, aryl halides, silole compounds, and boron-containing compounds. An electron transport material having polymerizable functional groups may be used as the electron transport material, and a base layer may be formed as a cured film by copolymerizing it with the above-mentioned monomers having polymerizable functional groups. Examples of metal oxide particles include indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, zinc oxide, and aluminum oxide. Silicon dioxide particles can also be used. Examples of metal particles include gold, silver, and aluminum.

[0039] The metal oxide particles contained in the undercoat may be surface-treated using a surface treatment agent such as a silane coupling agent before use. Common methods are used for surface treatment of metal oxide particles. Examples include dry and wet methods.

[0040] The dry method involves stirring metal oxide particles in a high-speed mixer such as a Henschel mixer, while adding an aqueous alcohol solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent, uniformly dispersing the particles, and then drying them. In the wet method, metal oxide particles and a surface treatment agent are stirred in a solvent or dispersed using glass beads or the like in a sand mill. After dispersion, the solvent is removed by filtration or reduced-pressure distillation. After solvent removal, it is preferable to further bake the mixture at 100°C or higher.

[0041] The undercoat layer may further contain additives, such as known materials including metal particles like aluminum particles, conductive particles like carbon black, charge transport materials, metal chelate compounds, and organometallic compounds. The undercoat layer can be formed by preparing an undercoat coating solution containing the above-mentioned materials and solvents, forming this coating film on a support or conductive layer, and then drying and / or curing it. Examples of solvents used in the coating liquid for the undercoat include organic solvents such as alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, aliphatic halogenated hydrocarbon-based solvents, and aromatic compound-based solvents. In this disclosure, it is preferable to use alcohol-based solvents or ketone-based solvents. Dispersion methods for preparing coating liquids for the undercoat include methods using homogenizers, ultrasonic dispersers, ball mills, sand mills, roll mills, vibratory mills, attritors, and liquid impact type high-speed dispersers.

[0042] The thickness of the undercoat layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and particularly preferably 0.3 μm or more. Furthermore, the thickness of the undercoat layer is preferably 50 μm or less, more preferably 40 μm or less, more preferably 30 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less.

[0043] <Photosensitive layer> The photosensitive layers of electrophotographic photoreceptors are mainly classified into (1) multilayer photosensitive layers and (2) single-layer photosensitive layers. (1) A multilayer photosensitive layer is a photosensitive layer having a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material. (2) A single-layer photosensitive layer is a photosensitive layer containing both a charge generating material and a charge transport material.

[0044] (1) Stacked photosensitive layer The stacked photosensitive layer comprises a charge generation layer and a charge transport layer.

[0045] (1-1) Charge generation layer The charge generation layer preferably contains a charge generation material and a resin. Examples of charge-generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. The content of the charge generating material in the charge generating layer is preferably 40% to 85% by mass, and more preferably 60% to 80% by mass, relative to the total mass of the charge generating layer. Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, and polyvinyl chloride resin. Among these, polyvinyl butyral resin is more preferred.

[0046] Furthermore, the charge generation layer may contain additives such as antioxidants and ultraviolet absorbers. Specifically, these include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds. The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing the above-mentioned materials and solvents, forming this coating film on the undercoat layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. The thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0047] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a binder material. Examples of charge transport materials include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably 25% to 70% by mass, and more preferably 30% to 55% by mass, relative to the total mass of the charge transport layer.

[0048] A thermoplastic resin (hereinafter also referred to as "resin") is used as the binding material. Examples of thermoplastic resins include polyester resin, polycarbonate resin, acrylic resin, and polystyrene resin. Among these, polycarbonate resin and polyester resin are preferred. Polyarylate resin is particularly preferred among polyester resins. The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0049] Furthermore, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, and leveling agents. Specifically, examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, and boron nitride particles. The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvents, forming this coating film on the charge generating layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred. The thickness of the charge transport layer is preferably 5 μm to 50 μm, more preferably 8 μm to 40 μm, and particularly preferably 10 μm to 30 μm.

[0050] (2) Single-layer photosensitive layer A single-layer photosensitive layer can be formed by preparing a coating solution for a photosensitive layer containing a charge generating substance, a charge transporting substance, a resin, and a solvent, forming this coating film on an undercoat layer, and drying it. The charge generating substance, charge transporting substance, and resin are the same as the examples of materials in "(1) Multilayer Photosensitive Layer" above.

[0051] <Protective layer> In this disclosure, the protective layer is the surface layer of the electrophotographic photoreceptor. In this case, the protective layer contains a polymer of at least one polymerizable charge-transporting compound selected from the group consisting of compounds represented by formulas (CT-1) and (CT-2), and the protective layer has a storage modulus (G') > loss modulus (G") at room temperature in kinematic viscoelasticity measurements, and has a Tanδ peak top in the temperature range of 85°C to 100°C. In this disclosure, the protective layer may further contain a polymer of a composition containing a thiol compound represented by formula (T-1). The polymerizable charge-transporting compound used in the surface layer of the electrophotographic photoreceptor is more preferably the compound represented by formula (CT-1).

[0052] The protective layer may contain additives such as antioxidants, UV absorbers, plasticizers, and leveling agents. Specifically, examples include hindered phenol compounds, hindered amine compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, and silicone compounds. Examples of silicone compounds include silicone-modified acrylic resins having acryloyloxy groups or methacryloyloxy groups. In this case, silicone compounds having methacryloyloxy groups are more preferred. The protective layer can be formed by preparing a protective coating solution containing the above-mentioned materials and solvents, forming this coating film on the photosensitive layer, and drying and / or curing it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

[0053] <Surface treatment of electrophotographic photoreceptors> In this disclosure, the surface of the electrophotographic photoreceptor may be processed. By processing the surface, the behavior of the cleaning means (cleaning blade) that comes into contact with the electrophotographic photoreceptor can be made more stable. Methods of surface processing include pressing a mold having protrusions onto the surface of the electrophotographic photoreceptor to transfer the shape, creating an uneven shape by mechanical polishing, or roughening the surface of the electrophotographic photoreceptor by impacting it with powder. By providing recesses or protrusions on the surface layer of the electrophotographic photoreceptor in this way, the behavior of the cleaning means that comes into contact with the electrophotographic photoreceptor can be made more stable.

[0054] The recesses or protrusions described above may be formed over the entire surface of the electrophotographic photoreceptor, or on a portion of the surface of the electrophotographic photoreceptor. If the recesses or protrusions are formed on a portion of the surface of the electrophotographic photoreceptor, it is preferable that the recesses or protrusions are formed over at least the entire contact area with the cleaning means (cleaning blade). To form a recess, a mold having a convex portion corresponding to the recess is pressed against the surface of the electrophotographic photoreceptor, and the shape is transferred, thereby forming a recess on the surface of the electrophotographic photoreceptor.

[0055] <Polishing equipment> An example of the polishing apparatus for electrophotographic photoreceptors described herein is shown in Figure 2. Figure 2 shows an apparatus for polishing a cylindrical electrophotographic photoreceptor using a polishing sheet. In Figure 2, the polishing sheet 2-1 is wound around a hollow shaft 2-6, and a motor (not shown) is positioned so that tension is applied to the polishing sheet 2-1 in the opposite direction to the direction in which the polishing sheet 2-1 is fed to the shaft 2-6. The polishing sheet 2-1 is fed in the direction of the arrow, passes through guide rollers 2-2a and 2-2b to a backup roller 2-3, and after polishing, the polishing sheet 2-1 is wound onto a winding means 2-5 by a motor (not shown) via guide rollers 2-2c and 2-2d. Polishing is performed by constantly pressing the polishing sheet 2-1 against the workpiece (electrophotographic photoreceptor before polishing) 2-4. Since the polishing sheet 2-1 is often insulating, it is preferable to use a material that is grounded or conductive at the contact points of the polishing sheet 2-1.

[0056] The feed speed of the abrasive sheet 2-1 is preferably in the range of 10 to 1000 mm / min. If the feed rate is too low, the binder resin may adhere to the surface of the abrasive sheet 2-1, which may result in deep scratches on the surface of the workpiece 2-4. The workpiece 2-4 is placed facing the backup roller 2-3 via the abrasive sheet 2-1. The backup roller 2-3 is preferably elastic in order to improve the uniformity of the surface roughness of the workpiece 2-4. In this process, the workpiece 2-4 and the backup roller 2-3 are pressed together for a predetermined time at a desired setting value via the abrasive sheet 2-1, and the surface of the workpiece 2-4 is polished. The rotation direction of the workpiece 2-4 may be the same as the direction in which the abrasive sheet 2-1 is fed, or it may be opposite. Furthermore, the rotation direction may be changed during polishing.

[0057] The pressure applied by the backup rollers 2-3 against the workpiece 2-4 depends on the hardness of the backup rollers 2-3 and the polishing time, but is approximately 0.005 to 15 N / m 2 It is preferable. The surface roughness of the electrophotographic photoreceptor can be adjusted by appropriately selecting the feed speed of the abrasive sheet 2-1, the pressure applied by the backup roller 2-3, the type of abrasive grain of the abrasive sheet, the film thickness of the binder resin on the abrasive sheet, and the thickness of the substrate.

[0058] <Measurement of the maximum height Rmax in JIS B0601 1982> The surface roughness of the electrophotographic photoreceptor can be measured by known means. For example, surface roughness meters such as the Surf Coater SE3500 type surface roughness measuring instrument manufactured by Kosaka Laboratory Ltd., and microscopes capable of acquiring three-dimensional shapes such as the ultra-depth shape measuring microscope VK-8550 and VK-9000 manufactured by Keyence Corporation can be mentioned.

[0059] <Process cartridge, electrophotographic apparatus> The electrophotographic photoreceptor of the present disclosure may be one of the components of a process cartridge or an electrophotographic apparatus. The process cartridge integrally supports the electrophotographic photoreceptor described so far and at least one means selected from the group consisting of charging means, developing means, and cleaning means, and is detachable from the electrophotographic apparatus main body. Further, the electrophotographic apparatus is characterized by having at least one means selected from the group consisting of the electrophotographic photoreceptor, charging means, exposure means, developing means, and transfer means described so far.

[0060] FIG. 3 shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge including the electrophotographic photoreceptor of the present disclosure. The cylindrical (drum-shaped) electrophotographic photoreceptor 201 is rotationally driven at a predetermined peripheral speed (process speed) in the direction of the arrow about the axis 202. The surface of the electrophotographic photoreceptor 201 is charged to a positive or negative predetermined potential by the charging means 203 during the rotation process. In FIG. 3, a roller charging method using a roller-type charging member is shown, but charging methods such as corona charging, proximity charging, and injection charging may be adopted. The surface of the charged electrophotographic photoreceptor 201 is irradiated with exposure light 204 from an exposure means (not shown), and an electrostatic latent image corresponding to the target image information is formed. The exposure light 204 is light intensity-modulated corresponding to the time-series electrical digital image signal of the target image information, and is output from an image exposure means such as slit exposure or laser beam scanning exposure, for example.

[0061] The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 201 is developed (normal development or reverse development) by toner on the developing member 213 housed in the developing means 205, and a toner image is formed on the surface of the electrophotographic photoreceptor 201. The toner image formed on the surface of the electrophotographic photoreceptor 201 is transferred to the transfer material 207 by the transfer means 206. At this time, a bias voltage with the opposite polarity to the charge held by the toner is applied to the transfer means 206 from a bias power supply (not shown). If the transfer material 207 is paper, the transfer material 207 is taken out from the paper feeding unit (not shown) and fed between the electrophotographic photoreceptor 201 and the transfer means 206 in synchronization with the rotation of the electrophotographic photoreceptor 201.

[0062] The transfer material 207, onto which the toner image has been transferred from the electrophotographic photoreceptor 201, is separated from the surface of the electrophotographic photoreceptor 201 and transported to the fixing means 208, where it undergoes a toner image fixing process and is printed out as an image-forming product (print, copy) outside the electrophotographic apparatus. The electrophotographic apparatus may also have a cleaning means 209 for removing any toner or other deposits remaining on the surface of the electrophotographic photoreceptor 201 after the transfer. Alternatively, a so-called cleanerless system may be used, in which the deposits are removed by a developing means or the like without a separate cleaning means.

[0063] A process cartridge can be formed by housing multiple components selected from the above-mentioned components, such as the electrophotographic photoreceptor 201, charging means 203, developing means 205, and cleaning means 209, in a container and supporting them integrally. Furthermore, it can be configured to be detachable from the electrophotographic apparatus body. For example, at least one selected from the charging means 203, developing means 205, and cleaning means 209 can be integrally supported together with the electrophotographic photoreceptor 201 to form a cartridge. This can then be further made into a process cartridge 211 that is detachable from the electrophotographic apparatus body using guide means 212 such as rails on the electrophotographic apparatus body. The electrophotographic apparatus may have a static elimination mechanism that removes static electricity from the surface of the electrophotographic photoreceptor 201 with pre-exposure light 210 from a pre-exposure means (not shown). In addition, guide means 212 such as rails may be provided for attaching and detaching the process cartridge 211 to the electrophotographic apparatus body. The electrophotographic apparatus of this disclosure may include an electrophotographic photoreceptor 201, as well as a charging means 203, an exposure means, a developing means 205, and a transfer means 206.

[0064] Figure 4 shows an example of a schematic configuration of a process cartridge equipped with the electrophotographic photoreceptor of this disclosure, and Figure 5 shows an example of a schematic configuration of an electrophotographic apparatus having the process cartridge of Figure 4. In Figure 4, the cylindrical electrophotographic photoreceptor 1 is driven to rotate at a predetermined peripheral speed in the direction of the arrow. The peripheral surface of the rotating electrophotographic photoreceptor 1 is uniformly charged to a predetermined positive or negative potential by the charging means 2. Next, the charged peripheral surface of the electrophotographic photoreceptor 1 receives exposure light (image exposure light) 3 output from an exposure means (not shown), such as slit exposure or laser beam scanning exposure. In this way, an electrostatic latent image corresponding to the desired image is sequentially formed on the peripheral surface of the electrophotographic photoreceptor 1. The voltage applied to the charging means (charging roller, etc.) 2 may be either a voltage with an AC component superimposed on a DC component, or a voltage with only a DC component.

[0065] The electrostatic latent image formed on the circumferential surface of the electrophotographic photoreceptor 1 is developed by the toner contained in the developer of the developing means 4 to form a toner image. Next, the toner image formed and supported on the circumferential surface of the electrophotographic photoreceptor 1 is sequentially transferred to the transfer material (paper, intermediate transfer material, etc.) 6 by the transfer bias from the transfer means (transfer roller, etc.) 5. The transfer material 6 is fed in synchronization with the rotation of the electrophotographic photoreceptor 1. After toner image transfer, the surface of the electrophotographic photoreceptor 1 is treated to remove static electricity by pre-exposure light 7 from a pre-exposure means (not shown), and then cleaned by a cleaning means 8 to remove any remaining toner. The electrophotographic photoreceptor 1 is then repeatedly used for image formation. The pre-exposure means may be performed before or after the cleaning process, and is not necessarily required.

[0066] The electrophotographic photoreceptor 1 may be mounted in an electrophotographic device such as a copier or a laser beam printer. Alternatively, a process cartridge 9 may be constructed by housing and supporting multiple components, such as the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8, in a container, and making it detachable from the main body of the electrophotographic device. In Figure 4, the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8 are supported together in a process cartridge 9 that is detachable from the main body of the electrophotographic device.

[0067] Next, an electrophotographic apparatus equipped with the electrophotographic photoreceptor of this disclosure will be described. Figure 5 shows an example of the configuration of the electrophotographic apparatus of this disclosure. Process cartridges 17 for yellow, 18 for magenta, 19 for cyan, and 20 for black, corresponding to yellow, magenta, cyan, and black respectively, are arranged side by side along the intermediate transfer body 10. The diameter, constituent materials, developer, charging method, and other means of the electrophotographic photoreceptor do not necessarily have to be the same for each color.

[0068] When the image formation operation begins, toner images of each color are sequentially superimposed on the intermediate transfer body 10 according to the image formation process described above. In parallel, the transfer paper 11 is fed from the paper tray 13 by the paper feed path 12 and is fed to the secondary transfer means 14 in time with the rotation of the intermediate transfer body 10. The toner image on the intermediate transfer body 10 is transferred to the transfer paper 11 by the transfer bias from the secondary transfer means 14. The toner image transferred onto the transfer paper 11 is transported along the paper feed path 12, fixed onto the transfer paper by the fixing means 15, and then discharged from the paper discharge unit 16. The electrophotographic photoreceptor of this disclosure can be used in laser beam printers, LED printers, copiers, facsimile machines, and multifunction devices thereof. [Examples]

[0069] The present disclosure will be described in further detail below using examples and comparative examples, but will not be limited thereto. In the following descriptions of examples, "parts" refers to mass unless otherwise specified.

[0070] <Synthesis of charge-transporting compounds represented by formula (CT-1)> The compound represented by formula (CT-1) in this disclosure can be synthesized, for example, using the synthesis method described in Japanese Patent Application Publication No. 2010-156835.

[0071] [Example 1-1] (Support) As the support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) that had been machined was used. Ultrasonic cleaning was performed in a cleaning solution containing detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water, followed by rinsing off the cleaning solution, and then further ultrasonic cleaning in pure water to degrease the cylinder, which was then used as the support.

[0072] (Bottom layer 1) Zinc oxide particles (specific surface area: 19 m²) 2100 parts of zinc oxide (powder resistance: 4.7 × 10⁶ Ω·cm) were mixed with 500 parts of toluene and stirred. 0.8 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) were added and the mixture was stirred for 6 hours. After that, the toluene was removed by distillation under reduced pressure, and the mixture was heated and dried at 130°C for 6 hours to obtain surface-treated zinc oxide particles A.

[0073] Next, 15 parts of polyvinyl butyral (trade name: S-Rec® BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 15 parts of blocked isocyanate (trade name: Duranate® TPA-B80E, non-volatile content 80% by mass, manufactured by Asahi Kasei Chemicals Corporation) were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. To this solution, 80.8 parts of surface-treated zinc oxide particles A and 0.81 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was dispersed for 3 hours at 23±3℃ using a sand mill apparatus with glass beads with a diameter of 0.8 mm.

[0074] After dispersion treatment, 0.01 parts of silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (formerly Toray Dow Corning Silicone Co., Ltd.)) and 5.6 parts of cross-linked polymethyl methacrylate (PMMA) particles (product name: Techpolymer® SSX-103, manufactured by Sekisui Chemical Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer. The obtained undercoating solution was applied to the support by immersion to form a coating film, and the coating film was dried at 160°C for 30 minutes to form an undercoating layer 1 with a thickness of 18 μm.

[0075] (Charge generation layer) Four parts of hydroxygallium phthalocyanine crystals (charge-generating material) in a crystalline form having strong peaks at 7.4° and 28.1° of the Bragg angle 2θ±0.2° in CuKα characteristic X-ray diffraction, and 0.04 parts of the compound represented by formula (E) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. Subsequently, the mixture was dispersed for 1 hour in a sand mill using 1 mm diameter glass beads under an atmosphere of 23±3°C. After dispersion, 100 parts of ethyl acetate were added to prepare a coating solution for the charge-generating layer. This charge generation layer coating solution was applied to the undercoat layer 1 by immersion, and the resulting coating film was dried at 90°C for 10 minutes to form a charge generation layer with a thickness of 0.15 μm. [ka]

[0076] (charge transport layer) A coating solution for the charge transport layer was prepared by dissolving 60 parts of the compound represented by formula (F), 30 parts of the compound represented by formula (G), 10 parts of the compound represented by formula (H), 100 parts of bisphenol Z type polycarbonate resin (product name: Yupiron Z400, manufactured by Mitsubishi Engineering Plastics Corporation), and 0.2 parts of polycarbonate having the structural unit represented by formula (I) (viscosity-average molecular weight Mv: 20000) in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane.

[0077] This charge transport layer coating solution was applied to the charge generation layer by immersion to form a coating film, and the resulting coating film was dried at 115°C for 50 minutes to form a charge transport layer with a thickness of 18 μm. [ka] [ka] [ka] [ka] (In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0078] (protective layer) Next, as the compound represented by formula (CT-1), 60 parts of the compound represented by formula (CT1-1) were dissolved in 70 parts of n-propanol, and then 70 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeolora® hyH, manufactured by Nippon Zeon Co., Ltd.) were added to prepare a protective coating solution. After that, the solution was filtered using a polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare the protective coating solution.

[0079] The protective coating solution was applied to the charge transport layer by immersion to form a coating film, and the resulting film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an accelerating voltage of 70kV and an absorbed dose of 15kGy in a nitrogen atmosphere. Subsequently, the coating film was heat-treated for 15 seconds under conditions of a nitrogen atmosphere to reach a temperature of 135°C. The oxygen concentration from electron beam irradiation to the 15-second heat treatment was 15ppm. Next, the coating film was allowed to cool naturally in air until its temperature reached 25°C, and then heat-treated for 1 hour to reach a temperature of 105°C to form a protective layer with a thickness of 5μm. In this way, an electrophotographic photoreceptor having a support and a surface layer before surface polishing was fabricated. The kinematic viscoelasticity measurements of the fabricated protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 90°C.

[0080] <Surface treatment of electrophotographic photoreceptors> (Polishing of the electrophotographic photoreceptor before surface polishing) The surface of the electrophotographic photoreceptor was polished before surface shaping was formed. Polishing was performed using the polishing apparatus shown in Figure 2 under the following conditions. Abrasive sheet feed speed: 400 mm / min Rotation speed of the electrophotographic photoreceptor: 450 rpm Pressing the electrophotographic photoreceptor onto the backup roller; 3.5 mm Rotation direction of the polishing sheet and electrophotographic photoreceptor; with

[0081] [Examples 1-2 to 5] Electrophotographic photoreceptors were fabricated in the same manner as in Example 1-1, except that the polymerizable charge transport compound represented by formula (CT1-1) was replaced with the compounds represented by formulas (CT1-2), (CT1-8), (CT1-7), and (CT1-6) in the formation of the protective layer. The kinematic viscoelasticity measurements of the fabricated protective layers all showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperatures of Tanδ were 93°C, 96°C, 94°C, and 91°C, respectively.

[0082] [Examples 1-6, 7] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was changed to the compounds represented by formulas (CT1-10) and (CT1-12), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT1-10) or (CT1-12) in the composition was denoted as WCT, and the content of Karenz MT PE1 was denoted as WT, the composition was formulated so that WT / WCT = 0.06. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less in both cases. Electrophotographic photoreceptors were fabricated under the same conditions as in Example 1-1, except for these factors. The kinematic viscoelasticity measurements of the fabricated protective layers showed that storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperatures of Tanδ were 88°C and 86°C, respectively.

[0083] [Examples 1-8, 9] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was replaced with the compounds represented by formulas (CT1-4) and (CT1-11), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, a protective layer coating solution was prepared in which the content of the polymerizable charge transport compound represented by formula (CT1-4) or (CT1-11) in the composition was denoted as WCT, and the content of Karenz MT PE1 was denoted as WT, such that WT / WCT = 0.03. This protective layer coating solution was applied to the charge transport layer by immersion to form a coating film, and the resulting coating film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an accelerating voltage of 58 kV and an absorbed dose of 15 kGy in a nitrogen atmosphere. Subsequently, the coating film was heat-treated for 15 seconds under conditions of 135°C in a nitrogen atmosphere. The oxygen concentration from electron beam irradiation to the 15-second heat treatment was 15 ppm. Next, the coating film was allowed to cool naturally in air until its temperature reached 25°C, and then heat-treated for 1 hour under conditions of 105°C to form a protective layer with a thickness of 5 μm. At this time, the amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found to be 2550-2600 cm⁻¹, derived from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or greater. Electrophotographic photoreceptors were fabricated under the same conditions as in Example 1-1. The kinematic viscoelasticity measurements of the fabricated protective layers showed that storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperatures for Tanδ were 86°C and 89°C.

[0084] [Examples 1-10, 11] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was replaced with the compounds represented by formulas (CT1-5) and (CT1-9), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT1-5) or (CT1-9) in the composition was denoted as WCT, and the content of Karenz MT PE1 was denoted as WT, the composition was formulated so that WT / WCT = 0.02. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under all other conditions, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The results of the kinematic viscoelasticity measurements of the prepared protective layers all showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperatures of Tanδ were 86°C and 88°C.

[0085] [Examples 1-12] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was changed to the compound represented by formula (CT1-3), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Co., Ltd., a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT-3) in the composition was denoted as WCT and the content of Karenz MT PE1 as WT, the composition was formulated so that WT / WCT = 0.02, and 3 parts of a silicone-modified acrylic resin solution (product name: Cymac® US-270, manufactured by Toagosei Co., Ltd.) was added. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and the result showed that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under conditions other than these, the electrophotographic photoreceptor was fabricated in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the fabricated protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 85°C.

[0086] [Examples 1-13, 14] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was changed to the compound represented by formula (CT2-1) or (CT2-2), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT2-1) or (CT2-2) in the composition was denoted as WCT, and the content of Karenz MT PE1 was denoted as WT, the content was adjusted so that WT / WCT = 0.02. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Electrophotographic photoreceptors were fabricated under the same conditions as in Example 1-1. The kinematic viscoelasticity measurements of the fabricated protective layers showed that storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperatures for Tanδ were 95°C and 100°C.

[0087] [Examples 1-15] In forming the protective layer, a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, the composition was formulated so that the WT / WCT value was 0.01, with WCT being the content of the polymerizable charge transport compound represented by formula (CT1-1) and WT being the content of Karenz MT PE1. The amount of residual SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550-2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under conditions other than these, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 97°C.

[0088] [Examples 1-16] In forming the protective layer, a polymer of Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, the composition was formulated so that the WT / WCT value was 0.07, with WCT being the content of the polymerizable charge transport compound represented by formula (CT1-1) and WT being the content of Karenz MT PE1. The amount of residual SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550-2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under all other conditions, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 88°C.

[0089] [Examples 1-17] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was changed to the compound with one methacryloyl functional group represented by formula (CT1-13), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis (3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT1-13) in the composition was denoted as WCT and the content of Karenz MT PE1 as WT, the content was adjusted so that WT / WCT = 0.02. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under conditions other than these, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 87°C. [ka]

[0090] [Examples 1-18] In forming the protective layer, the polymerizable charge transport compound represented by formula (CT1-1) was changed to the compound with two methacryloyl functional groups represented by formula (CT1-14), and a polymer of Karenz MT PE1 (pentaerythritol tetrakis (3-mercaptobutyrate), manufactured by Resonaq Corporation, a compound containing four secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, when the content of the polymerizable charge transport compound represented by formula (CT1-14) in the composition was denoted as WCT and the content of Karenz MT PE1 as WT, the content was adjusted so that WT / WCT = 0.02. The amount of remaining SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT PE1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT PE1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under conditions other than these, the electrophotographic photoreceptor was fabricated in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the fabricated protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 95°C. [ka]

[0091] [Examples 1-19] In forming the protective layer, a polymer of Karenz MT NR1 (1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by Resonaq Corporation, a compound containing three secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, the composition was formulated so that the WT / WCT value was 0.02, with WCT being the content of the polymerizable charge transport compound represented by formula (CT1-1) and WT being the content of Karenz MT NR1. The amount of residual SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550~2600 cm⁻¹ originated from the thiol compound Karenz MT NR1. -1The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT NR1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under conditions other than these, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 87°C.

[0092] [Examples 1-20] In forming the protective layer, a polymer of Karenz MT BD1 (1,4-bis(3-mercaptobutyryloxy)butane, manufactured by Resonaq Corporation, a compound containing two secondary thiol groups), which is a composition containing a thiol compound, was added. At this time, the composition was formulated so that the WT / WCT value was 0.02, with WCT being the content of the polymerizable charge transport compound represented by formula (CT1-1) and WT being the content of Karenz MT BD1. The amount of residual SH in the protective layer was confirmed by infrared absorption spectroscopy, and it was found that 2550-2600 cm⁻¹ originated from the thiol compound Karenz MT BD1. -1 The absorbance of the SH stretchable absorber in the range AT, derived from Karens MT BD1, is 1735~1750cm. -1 When the absorbance of the C=O stretch absorber of the ester group within the specified range is denoted as AE, it was confirmed that AT / AE was 0.001 or less. Under all other conditions, the electrophotographic photoreceptor was prepared in the same manner as in Example 1-1. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 89°C.

[0093] [Comparative Example 1-1] An electrophotographic photoreceptor was prepared in the same manner as in Example 1-1, except that the compound represented by formula (CT1-1) was replaced with the compound represented by formula (CT1-15), in which the functional group is an acrylic group, during the formation of the protective layer. The kinematic viscoelasticity measurement of the prepared protective layer showed that the storage modulus (G') > loss modulus (G") at room temperature, and the peak top temperature of Tanδ was 85°C. [Chemical]

[0094] [Comparative Examples 1-2] In the formation of the protective layer, the coating solution for the protective layer was dip-coated on the charge transport layer to form a coating film, and the obtained coating film was dried at 40 °C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under the conditions of an acceleration voltage of 70 kV and an absorption dose of 15 kGy in a nitrogen atmosphere. Then, a heat treatment was performed for 15 seconds under the condition that the temperature of the coating film reached 80 °C in a nitrogen atmosphere. The oxygen concentration from the irradiation of the electron beam to the heat treatment for 15 seconds was 15 ppm. Next, in the atmosphere, it was naturally cooled until the temperature of the coating film reached 25 °C, and then, a heat treatment was performed for 1 hour under the condition that the coating film reached 105 °C to form a protective layer with a film thickness of 5 μm. At this time, the dynamic viscoelasticity of the protective layer was prepared such that the storage modulus (G’) < loss modulus (G”) at room temperature. The peak top temperature of Tanδ was 60 °C. An electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that the relationship between the storage modulus G’ and the loss modulus G” in the measurement of dynamic viscoelasticity was changed so that G’ < G” at room temperature.

[0095] [Comparative Example 1-3] An electrophotographic photoreceptor was produced in the same manner as in Example 1-12, except that Kurenz MT PE1 was excluded in the formation of the protective layer. The result of the measurement of the dynamic viscoelasticity of the produced protective layer was that the storage modulus (G’) > loss modulus (G”) at room temperature, and the peak top temperature of Tanδ was 125 °C.

[0096] [Comparative Example 1-4] An electrophotographic photoreceptor was produced in the same manner as in Example 1-12, except that the content of the polymerizable charge transporting compound represented by the formula (CT1-1) and the content of Kurenz MT PE1 were changed so that the WT / WCT value became 0.09. The result of the measurement of the dynamic viscoelasticity of the produced protective layer was that the storage modulus (G’) > loss modulus (G”) at room temperature, and the peak top temperature of Tanδ was 75 °C.

[0097] [Examples 2-1 to 2-20, Comparative Examples 2-1 to 2-4] Examples 1-1 to 20 and Comparative Examples 1-1 to 1-4 were prepared in the same manner as in the preparation of the electrophotographic photoreceptors, except that undercoat layer 1 was replaced with undercoat layer 2 described below.

[0098] (Bottom layer 2) The undercoat layer 2 consists of two layers: a conductive layer and a nylon resin layer. First, the conductive layer was prepared by dispersing 60 parts by mass of TiO2 particles coated with oxygen-deficient SnO2 as conductive particles, 36.5 parts by mass of phenolic resin as a binder resin, and 20 parts by mass of methoxypropanol as a solvent in a horizontal sand mill disperser using glass beads with a diameter of 1 mm for an equivalent of 1 hour. Here, the TiO2 particles coated with oxygen-deficient SnO2 as conductive particles have a powder resistivity of 100 Ω·cm and a SnO2 coating rate (mass ratio) of 40%. The phenolic resin is trade name: Priofen J-325, manufactured by Dainippon Ink and Chemicals, Inc., with a resin solids content of 60%. 18 kg of glass beads were added to the horizontal sand mill, and the rotation speed of the dispersion disk during dispersion was set to 900 rpm.

[0099] The average particle size of the oxygen-deficient SnO2-coated TiO2 particles in this dispersion was 0.36 μm. To this dispersion, 1.5 parts by mass of silicone resin particles as a surface roughening agent and 0.001 parts by mass of silicone oil as a leveling agent were added and stirred to prepare a coating solution for the conductive layer. Here, the silicone resin particles are trade name: Tospar (registered trademark) 120, manufactured by Momentive Performance Materials Japan LLC, with an average particle size of 2 μm. The silicone oil is trade name: SH28PA, manufactured by Dow Toray Ltd.

[0100] A conductive layer with a thickness of 18 μm was formed by immersion coating of this conductive layer solution onto a support and drying and heat-curing it at 150°C for 30 minutes. For the nylon resin layer, a solution was prepared by dissolving 40 parts by mass of methoxymethylated nylon 6 resin (product name: Trezin EF-30T, manufactured by Nagase ChemteX Co., Ltd.) in a mixture of 400 parts by mass of methanol and 200 parts by mass of butanol. This solution was then immersion-coated onto the conductive layer, and the solution was heated and dried in a hot air dryer adjusted to 100°C for 30 minutes to cure the coating film, thereby forming a nylon resin layer with a thickness of 0.5 μm, which served as the undercoat layer 2.

[0101] Table 1 below shows the WT / WCT values, viscoelastic properties, Tanδ peak top temperature, and residual SH amount of each protective layer for Examples 1-1 to 1-20, 2-1 to 2-20, and Comparative Examples 1-1 to 1-4, 2-1 to 2-4.

[0102] [Table 1]

[0103] <Evaluation of electrophotographic photoconductors> The electrophotographic photoreceptors obtained in Examples 1-1 to 1-20, 2-1 to 2-20, and Comparative Examples 1-1 to 1-4, 2-1 to 2-4 were evaluated as follows.

[0104] [Evaluation device 1] The electrophotographic photoreceptors prepared in Examples 1-1 to 1-20 and Comparative Examples 1-1 to 1-4 were mounted on a Canon imageRUNNER ADVANCE C5051 copier and evaluated. For further details, the evaluation apparatus was set up in a normal temperature and humidity environment of 23°C and 50% RH. The fabricated electrophotographic photoreceptor was mounted on a cyan process cartridge, and the cartridge was then placed in the cyan process cartridge station for evaluation.

[0105] [Evaluation device 2] The electrophotographic photoreceptors prepared in Examples 2-1 to 2-20 and Comparative Examples 2-1 to 2-4 were mounted on a Canon imageRunner ADVANCE DX C3830 copier and evaluated. For further details, the evaluation apparatus was set up in a normal temperature and humidity environment of 23°C and 50% RH. The fabricated electrophotographic photoreceptor was mounted on a cyan process cartridge, and the cartridge was then placed in the cyan process cartridge station for evaluation.

[0106] (Abrasion resistance evaluation) Abrasion resistance evaluation was performed using evaluation apparatus 1 and evaluation apparatus 2 described above. First, the initial total film thickness of the manufactured electrophotographic apparatus and electrophotographic photoreceptor was measured using a film thickness measuring device (kett). The electrophotographic apparatus and electrophotographic photoreceptor were left in an environment of 23°C and 5% RH humidity for more than 24 hours, after which the electrophotographic photoreceptor was mounted in the cyan cartridge of the electrophotographic apparatus. Next, an image with a print ratio of 5% was printed in cyan monochrome on A4 size plain paper, and 100,000 copies were printed continuously. The electrophotographic photoreceptor after continuous printing was measured using a film thickness measuring device (kett), and the difference in film thickness between the initial total film thickness and the film thickness of the electrophotographic photoreceptor after continuous printing was calculated and defined as the amount of wear.

[0107] Regarding the calculated wear amount, in this disclosure, a wear resistance effect was determined to be obtained at a level of 2 μm or less, and among those, a wear amount of 1.5 μm or less was judged to be an excellent level. On the other hand, a wear amount of 2 μm or more was judged to be a level where the wear resistance effect was not obtained. Table 2 shows the evaluation results of the electrophotographic photoreceptors prepared in Examples 1-1 to 1-20, 2-1 to 2-20, and Comparative Examples 1-1 to 1-4, 2-1 to 2-4, performed using Evaluation Apparatus 1 and Evaluation Apparatus 2.

[0108] (Image flow evaluation) The suppression of image flow was evaluated using the evaluation devices 1 and 2 described above. After installing the manufactured electrophotographic photoreceptor into the copier, 5,000 sheets of A4 portrait-size paper with a print ratio of 5% were fed through in an environment of 30°C and 80% RH. Then, power to the copier was cut off and it was left to rest for 48 hours. Finally, a grid image (4 lines, 40 spaces) and a character image of repeated hiragana characters (Iroha image) were output on A4 portrait-size paper.

[0109] The image flow suppression effect was evaluated for the obtained images according to the following evaluation ranks. In this disclosure, ranks 5, 4, and 3 represent levels where image flow suppression is achieved, with rank 5 being judged to be an excellent level. On the other hand, ranks 1 and 2 represent levels where the image flow suppression effect of this disclosure is not achieved. Table 2 shows the evaluation results of the electrophotographic photoreceptors prepared in Examples 1-1 to 1-20, 2-1 to 2-20, and Comparative Examples 1-1 to 1-4, 2-1 to 2-4, performed using evaluation apparatus 1 and evaluation apparatus 2.

[0110] Rank 5: No image defects were observed in either the grid image or the Iroha character image. Rank 4: The grid image is partially blurred, but there are no image defects in the Iroha character image. Rank 3: The grid image is partially blurred, and the Iroha character image is partially faded. Rank 2: The grid image is partially missing, and the Iroha character image is completely faded. Rank 1: The grid image is completely gone, and the Iroha character image is completely faded.

[0111] [Table 2]

[0112] This embodiment includes the following configuration. (Composition 1) The surface layer contains a polymer of at least one polymerizable charge-transporting compound selected from the group consisting of compounds represented by formula (CT-1) and compounds represented by formula (CT-2), An electrophotographic photoreceptor characterized in that, in kinematic viscoelasticity measurements, the relationship between the storage modulus G' and the loss modulus G'' is G'>G'' at room temperature, and the surface layer has a Tanδ peak in the temperature range of 85°C to 100°C. [ka] (In formula (CT-1), Ar 11 ~Ar 13 Each of these independently represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by formula (P-1). [ka] (In formula (P-1), Z 11 represents an alkylene group with 1 to 6 carbon atoms, and * represents a bonding site with the structure shown by formula (CT-1) or (CT-2). [ka] (In formula (CT-2), Ar 21 ~Ar 24 Each of these independently represents either a substituted aryl group or an unsubstituted aryl group. 25 This represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by formula (P-1). (Configuration 2) The electrophotographic photoreceptor according to configuration 1, wherein the storage modulus G' is 1000 Pa or more and the loss modulus G'' is 1000 Pa or more. (Composition 3) The electrophotographic photoreceptor according to configuration 1 or 2, wherein the polymerizable charge transport compound is a compound represented by formula (CT-1). (Composition 4) The electrophotographic photoreceptor according to any one of configurations 1 to 3, wherein formula (CT-1) has two monovalent functional groups represented by formula (P-1). (Composition 5) The surface layer contains polymers of a composition containing the polymerizable charge transport compound and the thiol compound, The electrophotographic photoreceptor according to any one of configurations 1 to 4, characterized in that when the content of the polymerizable charge transporting compounds represented by formulas (CT-1) and (CT-2) in the composition is WCT and the content of the thiol compound is WT, WCT and WT satisfy formula (1). 0.01 ≤ WT / WCT ≤ 0.07 (1) (Composition 6) An electrophotographic photoreceptor according to any one of configurations 1 to 5, wherein WT / WCT in formula (1) is 0.01 or more and 0.03 or less. (Composition 7) The electrophotographic photoreceptor according to any one of configurations 1 to 6, wherein the thiol compound is a compound represented by formula (T-1). [ka] (In formula (T-1), Y represents a carbon atom or a heterocycle with 2 or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with 1 to 3 carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.) (Composition 8) The aforementioned surface layer, in infrared absorption measurements, has a range of 2550-2600 cm² derived from the formula (T-1). -1 Let AT be the absorbance of the SH stretch absorber of the thiol compound that exhibits an infrared absorption spectrum in the range, and the range derived from formula (T-1) is 1735-1750 cm⁻¹. -1 An electrophotographic photoreceptor according to any one of configurations 1 to 7, wherein when the absorbance of the C=O stretchable absorber of the ester group of the thiol compound exhibiting an infrared absorption spectrum in the range is denoted as AE, the AT and AE satisfy formula (2). AT / AE ≤ 0.001 (2) (Composition 9) The surface layer contains a polymer of a composition containing at least one polymerizable charge transporting compound selected from the group consisting of compounds represented by formula (CT-1) and compounds represented by formula (CT-2), and a thiol compound. An electrophotographic photoreceptor characterized in that, when the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the composition is WCT and the content of the thiol compound is WT, WCT and WT satisfy formula (1). 0.01 ≤ WT / WCT ≤ 0.07 (1) [ka] (In formula (CT-1), Ar 11 ~Ar 13 Each of these independently represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by formula (P-1). [ka] (In formula (P-1), Z 11 represents an alkylene group with 1 to 6 carbon atoms, and * represents a bonding site with the structure shown by formula (CT-1) or (CT-2). [ka] (In formula (CT-2), Ar 21 ~Ar 24 Each of these independently represents either a substituted aryl group or an unsubstituted aryl group. 25This represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by formula (P-1). (Composition 10) The electrophotographic photoreceptor according to configuration 9, wherein the thiol compound is a compound represented by formula (T-1). [ka] (In formula (T-1), Y represents a carbon atom or a heterocycle with 2 or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with 1 to 3 carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.) (Composition 11) The electrophotographic photoreceptor according to any one of configurations 1 to 10, wherein the surface layer contains a silicone compound having an acryloyloxy group or a methacryloyloxy group. (Composition 12) A process cartridge that integrally supports an electrophotographic photoreceptor as described in any one of configurations 1 to 11, and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachable from the main body of an electrophotographic apparatus. (Composition 13) An electrophotographic apparatus comprising an electrophotographic photoreceptor as described in any one of configurations 1 to 11, and at least one means selected from the group consisting of a charging means, an exposure means, a developing means, and a transfer means. [Explanation of Symbols]

[0113] 101 Support 102 Lower layer 103 Charge generation layer 104 Charge transport layer 105 Protective layer 2-1 Abrasive Sheet 2-2 Guide roller 2-3 Backup rollers 2-4 Object to be processed 2-5 Winding mechanism 2-6 axes 201 Electrophotographic photoreceptor 202 axis 203 Charging means 204 Exposure light 205 Developing means 206 Transfer means 207 Transfer material 208 Fixing means 209 Cleaning methods 210 Pre-exposure light 211 Process Cartridge 212 Guidance methods 213 Developing material 1. Electrophotographic photoreceptor 2. Charging means 3 Exposure light 4. Developing means 5. Transfer means 6 Transfer material 7. Pre-exposure light 8. Cleaning methods 9 Process Cartridges 10 Intermediate Transfer 11 Transfer paper 12 Paper feed path 13 Paper feed tray 14. Secondary transfer means 15 Fixing means 16 Paper output section 17 Process cartridge for yellow color 18 Process cartridges for magenta 19 Process cartridge for cyan 20 Process cartridges for black color

Claims

1. The surface layer contains a polymer of at least one polymerizable charge-transporting compound selected from the group consisting of the compound represented by formula (CT-1) and the compound represented by formula (CT-2), An electrophotographic photoreceptor characterized in that, in kinematic viscoelasticity measurements, the relationship between the storage modulus G' and the loss modulus G'' is G' > G'' at room temperature, and the surface layer has a Tanδ peak in the temperature range of 85°C to 100°C. 【Chemistry 1】 (In formula (CT-1), Ar １１ ~Ar １３ Each of these independently represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by formula (P-1). 【Chemistry 2】 (In formula (P-1), Z １１ (where * indicates an alkylene group having 1 to 6 carbon atoms, and * indicates a bonding site with the structure represented by formula (CT-1) or (CT-2).) 【Transformation 3】 (In formula (CT-2), Ar ２１ ~Ar ２４ Each of these independently represents either a substituted aryl group or an unsubstituted aryl group. ２５ This represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by formula (P-1).

2. The electrophotographic photoreceptor according to claim 1, wherein the storage modulus G' is 1000 Pa or more, and the loss modulus G'' is 1000 Pa or more.

3. The electrophotographic photoreceptor according to claim 1, wherein the polymerizable charge transport compound is a compound represented by formula (CT-1).

4. The electrophotographic photoreceptor according to claim 1, wherein formula (CT-1) has two monovalent functional groups represented by formula (P-1).

5. The surface layer contains polymers of a composition containing the polymerizable charge transport compound and the thiol compound, The electrophotographic photoreceptor according to claim 1, characterized in that when the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the composition is denoted as WCT and the content of the thiol compound as WT, WCT and WT satisfy formula (1). 0.01 ≤ WT / WCT ≤ 0.07 (1)

6. The electrophotographic photoreceptor according to claim 5, wherein WT / WCT in formula (1) is 0.01 or more and 0.03 or less.

7. The electrophotographic photoreceptor according to claim 5, wherein the thiol compound is a compound represented by formula (T-1). 【Chemistry 4】 (In formula (T-1), Y represents a carbon atom or a heterocycle with two or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with one to three carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.)

8. The aforementioned surface layer, in infrared absorption measurements, has a range of 2550 to 2600 cm² derived from formula (T-1). －１ Let AT be the absorbance of the S-H stretch absorber of the thiol compound that exhibits an infrared absorption spectrum in the range, and the range derived from formula (T-1) is 1735 to 1750 cm⁻¹. －１ The electrophotographic photoreceptor according to any one of claims 5 to 7, wherein when the absorbance of the C=O stretchable absorber of the ester group of the thiol compound exhibiting an infrared absorption spectrum in the range is denoted as AE, the AT and AE satisfy formula (2). AT / AE≦0.001 (2)

9. The surface layer contains a polymer of a composition containing at least one polymerizable charge transporting compound selected from the group consisting of compounds represented by formula (CT-1) and compounds represented by formula (CT-2), and a thiol compound. An electrophotographic photoreceptor characterized in that when the content of the polymerizable charge transport compounds represented by formulas (CT-1) and (CT-2) in the composition is denoted as WCT and the content of the thiol compound as WT, WCT and WT satisfy formula (1). 0.01 ≤ WT / WCT ≤ 0.07 (1) 【Transformation 5】 (In formula (CT-1), Ar １１ to Ar １３ each independently represents a substituted aryl group or an unsubstituted aryl group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 4 carbon atoms or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by formula (P-1).) 【Transformation 6】 (In formula (P-1), Z １１ (where * indicates an alkylene group having 1 to 6 carbon atoms, and * indicates a bonding site with the structure represented by formula (CT-1) or (CT-2).) 【Transformation 7】 (In formula (CT-2), Ar ２１ ~Ar ２４ Each of these independently represents either a substituted aryl group or an unsubstituted aryl group. ２５ This represents a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 4 carbon atoms, or a monovalent functional group represented by formula (P-1). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by formula (P-1).

10. The electrophotographic photoreceptor according to claim 9, wherein the thiol compound is a compound represented by formula (T-1). 【Transformation 8】 (In formula (T-1), Y represents a carbon atom or a heterocycle with two or more nitrogen atoms, and A represents a single bond, a hydrogen atom, or a linear alkylene group with one to three carbon atoms. m, n, o, and p represent integers of 0 or 1, and m+n+o+p is 2 or greater.)

11. The electrophotographic photoreceptor according to claim 1 or claim 9, wherein the surface layer contains a silicone compound having an acryloyloxy group or a methacryloyloxy group.

12. A process cartridge that integrally supports an electrophotographic photoreceptor according to claim 1 or claim 9 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachable from the body of an electrophotographic apparatus.

13. An electrophotographic apparatus comprising an electrophotographic photoreceptor according to claim 1 or claim 9, and at least one means selected from the group consisting of a charging means, an exposure means, a developing means, and a transfer means.

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