An electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt, and a method for manufacturing the electrophotographic apparatus

Abstract

To provide an electrophotographic device that has an electrophotographic photoreceptor manufactured by using a (meth)acrylic polymer containing fluorine atoms as a dispersant of fluorine atom-containing resin particles, and an intermediate transfer belt in contact with the photoreceptor and manufactured by using a (meth)acrylic polymer containing fluorine atoms as a dispersant of perfluoropolyether, and that prevents an image defect caused by exudation of perfluoropolyether from the intermediate transfer belt to the electrophotographic photoreceptor during long-term stop.SOLUTION: An electrophotographic device has an electrophotographic photoreceptor, and an intermediate transfer belt that may be in contact with the electrophotographic photoreceptor. The electrophotographic photoreceptor contains polytetrafluoroethylene particles, a binding material, and a polymer A having a specific structural unit. The intermediate transfer belt contains perfluoropolyether, a binding material, and a polymer B having a specific structural unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt for an electrophotographic apparatus, and a method for manufacturing the electrophotographic apparatus.

Background Art

[0002] As an electrophotographic photoreceptor mounted on an electrophotographic apparatus, those containing an organic photoconductive substance (charge generating substance) are widely used. In recent years, for the purpose of extending the life of the electrophotographic photoreceptor and achieving high image quality during repeated use, improvement in the mechanical durability (abrasion resistance) of the electrophotographic photoreceptor has been demanded. As a technique for improving the abrasion resistance of an electrophotographic photoreceptor, there is a method of reducing the friction between the surface layer of the electrophotographic photoreceptor and a contact member such as a cleaning blade by including fluorine atom-containing resin particles in the surface layer. Patent Document 1 discloses a technique for forming a surface layer using a dispersion liquid of fluorine atom-containing resin particles such as polytetrafluoroethylene resin particles as a coating liquid for the surface layer.

[0003] In addition, when preparing a dispersion liquid of fluorine atom-containing resin particles, a method of using a (meth)acrylic polymer containing fluorine atoms as a dispersant for the fluorine atom-containing resin particles for the purpose of enhancing dispersibility is known. Patent Document 2 discloses a technique for improving the dispersibility of fluorine atom-containing resin particles by using a fluorine atom-containing (meth)acrylic polymer having a specific structure as a dispersant.

[0004] In an electrophotographic image forming apparatus, a tandem method is widely adopted in which toner images of each color of YMCK are superimposed on an intermediate transfer belt and then collectively transferred onto paper to obtain a full-color image. Here, a semiconductive belt is generally used as the intermediate transfer belt, and typically known is a belt formed by dispersing carbon black in a resin such as polyimide and polyamideimide. Under such circumstances, in electrophotographic apparatuses that require high speed and high durability, further improvement in the transfer characteristics of the intermediate transfer belt is demanded. As one of the measures, efforts have been made to improve the transfer characteristics by performing various processes on the surface of the intermediate transfer belt. In Patent Document 3, in order to reduce the adhesion of the developer to the surface of the intermediate transfer body, an intermediate transfer body has been proposed in which the transfer efficiency is increased by coating the surface with a fluorine compound having water repellency and oil repellency. In addition, Patent Document 4 discloses a method of using a (meth)acrylic polymer containing fluorine atoms as a dispersant for perfluoropolyether in order to enhance the dispersibility when dispersing water-repellent perfluoropolyether in the surface layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] An electrophotographic apparatus having an electrophotographic photoreceptor with a surface layer excellent in the dispersibility of fluorine atom-containing resin particles produced by the technique disclosed in Patent Document 2 and an intermediate transfer belt with a surface layer excellent in the dispersibility of perfluoropolyether produced by the technique disclosed in Patent Document 4 and capable of contacting the electrophotographic photoreceptor is excellent in the abrasion resistance of the electrophotographic photoreceptor and excellent in the stable formation of high-quality electrophotographic images. However, when it stops for a long time with the electrophotographic photoreceptor and the intermediate transfer belt in contact, the perfluoropolyether dispersed in the surface layer of the intermediate transfer belt may ooze out and penetrate into the electrophotographic photoreceptor, resulting in image defects. Therefore, there is room for improvement in suppressing image defects caused by the bleeding of perfluoropolyether from the intermediate transfer belt to the electrophotographic photoreceptor after long-term stoppage in an electrophotographic apparatus having an electrophotographic photoreceptor produced by using a (meth)acrylic polymer containing a fluorine atom as a dispersant for fluorine atom-containing resin particles and an intermediate transfer belt that contacts the photoreceptor and is produced by using a (meth)acrylic polymer containing a fluorine atom as a dispersant for perfluoropolyether.

[0007] One aspect of the present disclosure is directed to providing an electrophotographic apparatus in which image defects caused by the bleeding of perfluoropolyether from an intermediate transfer belt to an electrophotographic photoreceptor are suppressed. Another aspect of the present disclosure is directed to providing a method for manufacturing the electrophotographic apparatus.

Means for Solving the Problems

[0008] According to one aspect of the present disclosure, An electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt capable of contacting the electrophotographic photoreceptor, wherein the electrophotographic photoreceptor has polytetrafluoroethylene particles, a binder material, a polymer A having a structural unit having a perfluoroalkyl group, and has a surface layer containing the same, wherein the intermediate transfer belt has A perfluoropolyether, a binder material, a polymer B having a structural unit having a perfluoroalkyl group, and having a surface layer containing the same, wherein the polymer A has a structural unit represented by the following formula (1) as the structural unit having a perfluoroalkyl group, and the polymer B has a structural unit represented by the following formula (2) as the structural unit having a perfluoroalkyl group [Chemical formula] (In formula (1), R 11 represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf 1 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) [Chemical formula] (In formula (2), R 12 represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf 2 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) An electrophotographic apparatus is provided, which is characterized by the above. According to another aspect of the present disclosure, a method for manufacturing the electrophotographic apparatus is provided. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, there is provided an electrophotographic photoreceptor excellent in dispersibility of polytetrafluoroethylene particles as fluorine atom-containing resin particles in a surface layer, and an intermediate transfer belt excellent in dispersibility of perfluoropolyether in a surface layer capable of contacting the electrophotographic photoreceptor, and an electrophotographic apparatus in which image defects caused by bleeding of perfluoropolyether from the intermediate transfer belt to the electrophotographic photoreceptor after long-term stoppage are suppressed can be provided. [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described in detail with reference to preferred embodiments. As a result of the studies by the present inventors, an electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt that can come into contact with the electrophotographic photoreceptor, wherein the electrophotographic photoreceptor has a surface layer containing polytetrafluoroethylene particles, a binder material, and a polymer A having a structural unit having a perfluoroalkyl group, and the intermediate transfer belt has a surface layer containing a perfluoropolyether, a binder material, and a polymer B having a structural unit having a perfluoroalkyl group, and the polymer A has a structural unit represented by the following formula (1) as the structural unit having a perfluoroalkyl group, and the polymer B has a structural unit represented by the following formula (2) as the structural unit having a perfluoroalkyl group. It has been found that an electrophotographic apparatus characterized by this can suppress the occurrence of image defects caused by the bleeding of perfluoropolyether from the intermediate transfer belt during long-term stoppage to the surface of the electrophotographic photoreceptor.

Chemical Formula

Chemical formula

[0012] Here, the present inventors consider that the polymer A having the structural unit represented by the formula (1) functions as a dispersant for polytetrafluoroethylene particles in the step of preparing a coating liquid for the surface layer for forming the surface layer of the electrophotographic photoreceptor. Further, the present inventors consider that the polymer B having the structural unit represented by the formula (2) functions as a dispersant for perfluoropolyether in the step of preparing a coating liquid for the surface layer for forming the surface layer of the intermediate transfer belt.

[0013] Regarding the reason why the electrophotographic apparatus incorporating the electrophotographic photoreceptor and the intermediate transfer belt of the present disclosure is excellent in the effect of suppressing the occurrence of image defects that occur when printing after a long-term stop in a state where the electrophotographic photoreceptor and the intermediate transfer belt are in contact, the present inventors speculate as follows. When dispersing particles or liquids containing fluorine atoms in a resin, a dispersant containing fluorine atoms may be used to achieve uniform dispersion. The same applies when dispersing polytetrafluoroethylene particles in the surface layer of an electrophotographic photoreceptor or when dispersing perfluoropolyether in the surface layer of an intermediate transfer belt, and in both cases, a dispersant containing fluorine atoms may be used. When the same dispersant is used for the electrophotographic photoreceptor and the intermediate transfer belt that contacts the electrophotographic photoreceptor, or when a dispersant having a higher affinity for perfluoropolyether than the dispersant contained in the intermediate transfer belt that contacts the electrophotographic photoreceptor is used in the electrophotographic photoreceptor, image defects may occur when printing after a long-term stop with the electrophotographic photoreceptor and the intermediate transfer belt in contact. This is considered to be due to the perfluoropolyether dispersed in the surface layer of the intermediate transfer belt oozing out toward the surface of the electrophotographic photoreceptor with higher affinity and penetrating into the electrophotographic photoreceptor from the portion of the intermediate transfer belt in contact with the electrophotographic photoreceptor.

[0014] As a result of the study by the present inventors, an electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt that can contact the electrophotographic photoreceptor, wherein the electrophotographic photoreceptor has a surface layer containing polytetrafluoroethylene particles, a binder material, and a polymer A having a structural unit having a perfluoroalkyl group, and the intermediate transfer belt has a surface layer containing perfluoropolyether, a binder material, and a polymer B having a structural unit having a perfluoroalkyl group, and the polymer A has a structural unit represented by the formula (1) as the structural unit having a perfluoroalkyl group, and the polymer B has a structural unit represented by the formula (2) as the structural unit having a perfluoroalkyl group. It has been found that the electrophotographic apparatus characterized by this suppresses the occurrence of image defects caused by the oozing of perfluoropolyether from the intermediate transfer belt to the surface of the electrophotographic photoreceptor when printing after a long-term stop with the electrophotographic photoreceptor and the intermediate transfer belt in contact.

[0015] The perfluoropolyether dispersed in the surface layer of the intermediate transfer belt has a higher affinity for polymer B having a structural unit with a polymerizable functional group being acrylic as shown in the formula (2) than for polymer A having a structural unit with a polymerizable functional group being methacrylic as shown in the formula (1). Therefore, it is considered that the transfer of the perfluoropolyether to the surface of the electrophotographic photoreceptor in which polymer A in contact is dispersed is suppressed as compared with the case where the electrophotographic photoreceptor and the intermediate transfer belt are used in combination using the same polymer.

[0016] <Polytetrafluoroethylene particles as fluorine atom-containing resin particles> The surface layer of the electrophotographic photoreceptor used in the electrophotographic apparatus of the present disclosure contains polytetrafluoroethylene particles as fluorine atom-containing resin particles. The content of the polytetrafluoroethylene particles in the surface layer is preferably 5% by mass or more and 40% by mass or less based on the total mass of the surface layer.

[0017] In the cross-sectional observation of the surface layer, the average primary particle diameter, which is the arithmetic mean of the major axis diameters of the primary particles measured from the secondary electron image by a scanning electron microscope, of the polytetrafluoroethylene particles is preferably 150 nm or more and 300 nm or less from the viewpoints of improving dispersibility and suppressing potential fluctuations. Further, the average primary particle diameter of the polytetrafluoroethylene particles is more preferably 180 nm or more and 250 nm or less. The polytetrafluoroethylene particles preferably have an average value of roundness (average roundness) calculated from the area and perimeter of the primary particles measured from the secondary electron image by a scanning electron microscope of 0.75 or more. In order to keep the measured values of the average primary particle diameter and the average roundness of the polytetrafluoroethylene particles contained in the surface layer of the electrophotographic photoreceptor of the present disclosure within the above ranges, the polytetrafluoroethylene particles may be measured by the following method and the values of the average primary particle diameter and the average roundness calculated are within the above ranges.

[0018] (Measurement method of average primary particle diameter and average roundness) That is, in the examples of the present disclosure, the average primary particle diameter and average roundness of the polytetrafluoroethylene particles contained in the surface layer of the electrophotographic photoreceptor were measured as follows using a field emission scanning electron microscope (FE-SEM). The polytetrafluoroethylene particles were attached to a commercially available carbon conductive tape, and the polytetrafluoroethylene particles not attached to the conductive tape were removed with compressed air, and platinum evaporation was performed. The deposited polytetrafluoroethylene particles were observed using an FE-SEM (S-4700) manufactured by Hitachi High-Technologies Corporation. The measurement conditions of the FE-SEM are as follows. Accelerating voltage: 2 kV WD: 5 mm Magnification: 20,000 times Number of pixels: 1280 pixels vertically and 960 pixels horizontally (size per pixel: 5 nm) From the obtained image, the Feret diameter of 100 particles was determined using ImageJ (open source software manufactured by the National Institutes of Health (NIH) of the United States), and the average value was calculated and taken as the average primary particle diameter. Similarly, the area and perimeter of the particles were determined, the roundness was determined from the following formula (II), the average value was calculated, and the average roundness of the particles was obtained. Roundness = 4 × π × (area) ÷ (square of perimeter) Formula (II) The polytetrafluoroethylene particles of the present disclosure may be used alone or in combination of two or more.

[0019] <Polymer A having a structural unit represented by formula (1) and polymer B having a structural unit represented by formula (2)> The surface layer of the electrophotographic photoreceptor incorporated in the electrophotographic apparatus of the present disclosure has a polymer A having a structural unit having a perfluoroalkyl group, and the polymer A has a structural unit represented by the following formula (1) as the structural unit having a perfluoroalkyl group.

Chemical formula

Chemical formula

[0020] Examples of the structures of Rf 1 and Rf 2 include the structures shown below, for example.

Chemical formula

Chemical formula

[0021] Examples of the structural unit represented by the formula (1) contained in the polymer A having the structural unit represented by the formula (1) used in the present disclosure include the structures shown in Table 1 below.

[0022]

Table 1

[0023] In the polymer B having the structural unit represented by the formula (2) used in the present disclosure, examples of the structural unit represented by the formula (2) include the structures shown in Table 2 below.

[0024] [Table 2]

[0025] Rf in the formula (1) included in the polymer A contained in the surface layer of the electrophotographic photoreceptor of the present disclosure 1 has the number of carbon atoms NRf 1 and Rf in the formula (2) included in the polymer B contained in the surface layer of the intermediate transfer belt of the present disclosure 2 has the number of carbon atoms NRf 2 When it is defined as NRf 1 NRf 2 ≧NRf is preferable from the viewpoint of suppressing the bleeding of the perfluoropolyether in the surface layer of the intermediate transfer belt to the surface of the electrophotographic photoreceptor.

[0026] When the mass of the structural unit having the perfluoroalkyl group in the polymer A contained in the surface layer of the electrophotographic photoreceptor of the present disclosure is defined as MTA, and the mass of the structural unit represented by the formula (1) in the polymer A is defined as M1A, the following formula (i) is satisfied. And when the mass of the structural unit having the perfluoroalkyl group in the polymer B contained in the surface layer of the intermediate transfer belt of the present disclosure is defined as MTB, and the mass of the structural unit represented by the formula (2) in the polymer B is defined as M2B, it is preferable from the viewpoint of suppressing the bleeding of the perfluoropolyether in the surface layer of the intermediate transfer belt to the surface of the electrophotographic photoreceptor that the following formula (ii) is satisfied. 0.5 < M1A / MTA ≦ 1.0 ···(i) 0.5 < M2B / MTB ≦ 1.0 ···(ii)

[0027] Furthermore, satisfying the following formula (iii) is more preferable from the viewpoint of improving the dispersibility of polytetrafluoroethylene particles in the surface layer of the electrophotographic photoreceptor, and satisfying the following formula (iv) is more preferable from the viewpoint of improving the dispersibility of perfluoropolyether in the surface layer of the intermediate transfer belt. 0.7 < M1A / MTA ≤ 1.0 ···(iii) 0.7 < M2B / MTB ≤ 1.0 ···(iv) Furthermore, satisfying M1A / MTA = 1.0 and M2B / MTB = 1.0 is most preferable from the viewpoints of improving the dispersibility of polytetrafluoroethylene particles in the surface layer of the electrophotographic photoreceptor, improving the dispersibility of perfluoropolyether in the surface layer of the intermediate transfer belt, and suppressing the bleeding of perfluoropolyether in the surface layer of the intermediate transfer belt to the surface of the electrophotographic photoreceptor.

[0028] Among the polymer A contained in the surface layer of the electrophotographic photoreceptor of the present disclosure, the content of the structural unit represented by the formula (1) is preferably 5 to 50% by number based on all the structural units of the polymer A from the viewpoint of improving the dispersibility of polytetrafluoroethylene particles. Further, the content of the structural unit represented by the formula (1) is preferably 0.05 to 14.1% by mass based on all the structural units of the polymer A. Furthermore, the structural unit represented by the formula (1) is more preferably 20 to 45% by number based on all the structural units of the polymer A. Also, the structural unit represented by the formula (1) is more preferably 0.2 to 11.9% by mass based on all the structural units of the polymer A.

[0029] The weight average molecular weight of the polymer A having the structural unit represented by the formula (1) contained in the surface layer of the electrophotographic photoreceptor of the present disclosure is preferably 16,000 or more and 300,000 or less from the viewpoints of improving the dispersibility of polytetrafluoroethylene particles and suppressing potential fluctuations during repeated use. Furthermore, the weight average molecular weight of the polymer A having the structural unit represented by the formula (1) is more preferably 40,000 or more and 250,000 or less. The weight average molecular weight of the polymer A having the structural unit represented by the formula (1) can be measured and calculated by the following method.

[0030] (Measurement of weight average molecular weight by GPC) The weight average molecular weight according to the present disclosure is measured by gel permeation chromatography (GPC) as follows. First, at room temperature over 24 hours, the sample is dissolved in tetrahydrofuran (THF). Then, the obtained solution is filtered through a solvent-resistant membrane filter "Mae Sho Disc" (manufactured by Tosoh Corporation) with a pore diameter of 0.2 μm to obtain a sample solution. Note that the concentration of the components soluble in THF in the sample solution is adjusted to be about 0.8 mass%. Using this sample solution, measurement is performed under the following conditions. · Apparatus: HLC8120 GPC (Detector: RI) (manufactured by Tosoh Corporation) · Column: 7 columns of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK) · Eluent: Tetrahydrofuran (THF) · Flow rate: 1.0 ml / min · Oven temperature: 40.0 °C · Sample injection volume: 0.10 ml When calculating the molecular weight of the sample, a molecular weight calibration curve prepared using a standard polystyrene resin (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

[0031] In the surface layer of the electrophotographic photoreceptor of the present disclosure, the content of the polymer A having the structural unit represented by the formula (1) with respect to the polytetrafluoroethylene particles is preferably 2 mass% or more and 10 mass% or less, and more preferably 4 mass% or more and 8 mass% or less, from the viewpoints of improving dispersibility and suppressing potential fluctuations during repeated use.

[0032] The polymer A is preferably a polymer having a structural unit represented by the formula (1) and a structural unit represented by the following formula (M). The polymer B is preferably a polymer having a structural unit represented by the formula (2) and a structural unit represented by the following formula (M). More preferably, the polymer A has only the structural unit represented by the formula (1) and the structural unit represented by the formula (M) as structural units.

Chemical formula

Chemical formula

[0033] In the formula (M),

Chemical formula

[0034] In the formula (M),

Chemical formula

[0035] In the polymer A having the structural unit represented by the formula (1) and the structural unit represented by the formula (M), the ratio of the structural unit represented by the formula (1) to the structural unit represented by the formula (M) is preferably 1:19 to 1:1 in molar ratio, and more preferably 1:4 to 9:11.

[0036] In the polymer B having the structural unit represented by the formula (2) and the structural unit represented by the formula (M), the ratio of the structural unit represented by the formula (2) to the structural unit represented by the formula (M) is preferably 1:19 to 1:1 in molar ratio, and more preferably 1:4 to 9:11.

[0037] Examples of the structural unit represented by the formula (M) include the structures shown in Table 3 below.

[0038]

Table 3-1

Table 3-2

[0039] Polymer B contained in the surface layer of the intermediate transfer belt of the present disclosure functions as a dispersant for dispersing perfluoropolyether (PFPE) in a binder resin. The polymer B preferably has a number average molecular weight Mn in the range of 11,000 or more and 15,000 or less, and a peak top molecular weight Mp in the range of 24,000 or more and 40,000 or less in order to disperse PFPE in the binder resin.

[0040] By having a numerical range related to the number average molecular weight and the peak top molecular weight, the polymer B exhibits a high steric hindrance effect and can effectively suppress the aggregation of PFPEs. As a result, the domain size of PFPE in the binder resin can be made small, for example, with an average major axis of 1 nm or more and 60 nm or less, and a decrease in the glossiness of the surface of an electrophotographic belt such as an intermediate transfer belt can be prevented. Further, by having a numerical range related to the number average molecular weight and the peak top molecular weight, the dispersant can prevent the encounter probability with PFPE of the dispersant from becoming too low. As a result, the aggregation of PFPEs can be suppressed and an increase in the domain size can be suppressed. As a result, a decrease in the glossiness of the surface of the intermediate transfer belt can be prevented.

[0041] Here, the number average molecular weight and the peak top molecular weight are measured by a GPC device. Specifically, the dispersant is dissolved in tetrahydrofuran. The resulting solution is injected into a column (trade name; TSK-GEL MULTIPORE HXL-M; manufactured by Tosoh Corporation), and the column is passed through at a certain flow rate. The elution time distribution is measured by a gel permeation chromatograph device (HLC-8220 manufactured by Tosoh Corporation) that elutes the components adsorbed on the column, and from the result, the molecular weight distribution is calculated using a calibration curve prepared in advance from a polystyrene standard sample with a known molecular weight. From the result, the number average molecular weight is calculated. The peak top molecular weight is taken as the value of the mode in the number average molecular weight distribution.

[0042] By the following method, a polymer A having a structural unit with a perfluoroalkyl group and a polymer B having a structural unit with a perfluoroalkyl group, in which the number-average molecular weight and the peak-top molecular weight are within a predetermined numerical range, can be prepared. That is, the dispersant according to this embodiment can be prepared using a preparative HPLC apparatus (trade name: LC-908; manufactured by Nippon Analytical Industry Co., Ltd.). As the column, for example, "JAIGEL-1H", "JAIGEL-2H", "JAIGEL-3H", "JAIGEL-4H", and "JAIGEL-5H" (all trade names; manufactured by Nippon Analytical Industry Co., Ltd., diameter 20×600 mm: preparative column) can be used. Specifically, a polymer having a structural unit with a perfluoroalkyl group according to this embodiment is injected into the column, the solution is collected at each elution time, and dispersants with different molecular weight distributions are obtained. The molecular weight distribution of each solution is measured by the GPC apparatus. A dispersant having a desired peak-top molecular weight Mp is selected from the separated solutions whose molecular weight distributions have been measured. For the separated solution in which the peak-top molecular weight Mp is specified, when the number-average molecular weight of the separated solution is larger than the desired number-average molecular weight Mn, the number-average molecular weight Mn can be decreased without changing the peak-top molecular weight Mp by mixing the separated solution on the low molecular weight side. When the number-average molecular weight of the separated solution is smaller than the desired number-average molecular weight Mn, the number-average molecular weight Mn can be increased without changing the peak-top molecular weight Mp by mixing the separated solution on the high molecular weight side. In this way, the polymer A and the polymer B according to this embodiment can be obtained.

[0043] The content of the polymer B contained in the intermediate transfer belt of the present disclosure is preferably 5% by mass or more and 30% by mass or less, more preferably 15% by mass or more and 25% by mass or less, based on the mass of the total solid content of the surface layer.

[0044] <Electrophotographic photoreceptor> Fig. 1 shows an example of the layer structure of the electrophotographic photoreceptor used in the electrophotographic apparatus of the present disclosure. In Fig. 1, an undercoat layer 102, a charge generation layer 103, a charge transport layer 104, and a surface layer 105 are laminated on a support 101. The photosensitive layer may be composed of a laminated photosensitive layer having a charge generation layer and a charge transport layer, or may be composed of a single-layer photosensitive layer containing a charge generating substance and a charge transport substance. The surface layer of the electrophotographic photoreceptor of the present disclosure contains polytetrafluoroethylene particles, a binder material, and a polymer A having a structural unit represented by the formula (1). As a method for manufacturing the electrophotographic photoreceptor used in the electrophotographic apparatus of the present disclosure, there is a method of preparing coating liquids for each layer described later, coating the desired layers in order, and drying them. At this time, examples of the coating method of the coating liquid include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, and the like. Among these, dip coating is preferable from the viewpoints of efficiency and productivity.

[0045] Hereinafter, the configuration of the electrophotographic photoreceptor used in the electrophotographic apparatus of the present disclosure will be described. <Support> The support of the electrophotographic photoreceptor is preferably a conductive one (conductive support). Examples of the shape of the support include a cylindrical shape, a belt shape, and a sheet shape. Among them, a cylindrical support is preferable. Further, an electrochemical treatment such as anodic oxidation, a blasting treatment, a cutting treatment, or the like may be performed on the surface of the support. As the material of the support, metals, resins, glasses, etc. are preferable. Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among them, an aluminum support using aluminum is preferable. In addition, it is preferable to impart conductivity to resins and glasses by treatments such as mixing or coating with a conductive material.

[0046] <Conductive layer> A conductive layer may be provided on the support. By providing the conductive layer, it is possible to conceal scratches and unevenness on the surface of the support and to control the reflection of light on the support surface. The conductive layer preferably contains conductive particles and a resin. Examples of the material of the conductive particles include metal oxides, metals, carbon black, and the like. Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, bismuth oxide, and the like. Examples of the metal include aluminum, nickel, iron, chromium, copper, zinc, silver, and the like. Among these, it is preferable to use metal oxide particles as the conductive particles, and more preferably, titanium oxide particles, tin oxide particles, and zinc oxide particles. When using metal oxide particles as the 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 and aluminum or their oxides. Further, the conductive particles may have a laminated structure including core material particles and a coating layer covering the particles. Examples of the core material particles include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of the coating layer include metal oxide particles such as tin oxide. When using metal oxide particles as the conductive particles, the volume average particle diameter 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 the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, and the like. Further, the conductive layer may further contain a concealer such as silicone oil, resin particles, and titanium oxide. The conductive layer can be formed by preparing a coating solution for the conductive layer containing each of the above materials and a solvent, forming this coating film on a support, and drying it. Examples of the solvent used in the coating solution for the conductive layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like. Examples of the dispersion method for dispersing conductive particles in the coating solution for the conductive layer include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser. The film 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.

[0047] <Undercoat layer> In the present disclosure, an undercoat layer may be provided on the support or the conductive layer. By providing the undercoat layer, the interlayer adhesion function can be enhanced and a charge injection blocking function can be imparted. The undercoat layer preferably contains a resin. Further, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, cellulose resin, and the like. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include isocyanate group, blocked isocyanate group, methylol group, alkylated methylol group, epoxy group, metal alkoxyl group, hydroxy group, amino group, carboxy group, thiol group, carboxylic anhydride group, carbon-carbon double bond group, and the like.

[0048] Further, the undercoat layer may further contain an electron transport material, metal oxide particles, metal particles, a conductive polymer, etc. for the purpose of enhancing electrical characteristics. Among these, it is preferable to use an electron transport material and metal oxide particles. Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, aryl halide compounds, silole compounds, boron-containing compounds, and the like. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the monomer having the above-described polymerizable functional group to form an undercoat layer as a cured film. Examples of the metal oxide particles include particles of indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, zinc oxide, aluminum oxide, and the like. Silicon dioxide particles can also be used. Examples of the metal particles include particles of gold, silver, aluminum, and the like.

[0049] The metal oxide particles contained in the undercoat layer may be surface-treated using a surface treatment agent such as a silane coupling agent before use. As a method for surface-treating the metal oxide particles, a general method is used. For example, a dry method or a wet method can be mentioned. The dry method involves adding an alcohol aqueous solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent while stirring metal oxide particles in a mixer capable of high-speed stirring such as a Henschel mixer, uniformly dispersing them, and then drying. In the wet method, the metal oxide particles and the surface treatment agent are stirred in a solvent or dispersed using a sand mill or the like with glass beads or the like, and after dispersion, the solvent is removed by filtration or distillation under reduced pressure. After removal of the solvent, it is preferably baked at 100°C or higher.

[0050] The undercoat layer may further contain an additive, and for example, known materials such as metal particles such as aluminum particles, conductive particles such as carbon black, charge transport materials, metal chelate compounds, and organometallic compounds can be contained. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing each of the above materials and a solvent, forming this coating film on a support or a conductive layer, and drying and / or curing it. Examples of the solvent used in the coating solution for the undercoat layer include organic solvents such as alcohol, sulfoxide, ketone, ether, ester, aliphatic halogenated hydrocarbon, and aromatic compound. In the present disclosure, it is preferable to use alcohol-based and ketone-based solvents. Examples of the dispersion method for preparing the coating solution for the undercoat layer include methods using a homogenizer, ultrasonic disperser, ball mill, sand mill, roll mill, vibration mill, attritor, and liquid collision type high-speed disperser. The film 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. Also, the film 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.

[0051] <Photosensitive layer> The photosensitive layer of the electrophotographic photoreceptor is mainly classified into (1) a laminated photosensitive layer and (2) a single-layer photosensitive layer. (1) The laminated photosensitive layer is a photosensitive layer having a charge generation layer containing a charge generating substance and a charge transport layer containing a charge transport substance. (2) The single-layer photosensitive layer is a photosensitive layer containing both a charge generating substance and a charge transport substance.

[0052] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generation layer and a charge transport layer.

[0053] (1-1) Charge generation layer The charge generation layer preferably contains a charge generating substance and a resin. Examples of the charge generating material include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments, etc. Among these, azo pigments and phthalocyanine pigments are preferred. Among the phthalocyanine pigments, oxy titanium phthalocyanine pigments, chloro gallium phthalocyanine pigments, and hydroxy gallium phthalocyanine pigments are preferred. The content of the charge generating material in the charge generation layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generation layer. Examples of the resin include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, polyvinyl acetate resins, polyvinyl chloride resins, etc. Among these, polyvinyl butyral resins are more preferred. Also, the charge generation layer may further contain additives such as antioxidants and ultraviolet absorbers. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, etc. can be mentioned. The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing each of the above materials and a solvent, forming this coating film on a support, a conductive layer or an undercoat layer, and drying it. Examples of the solvent used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, etc. The film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, more preferably 0.15 μm or more and 0.4 μm or less.

[0054] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a binder material. When the protective layer described later is not provided, the charge transport layer becomes the surface layer of the electrophotographic photoreceptor. In this case, the charge transport layer contains fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the formula (1). Examples of the charge transport material 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% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 55% by mass or less, based on the total mass of the charge transport layer. As the binder material, a thermoplastic resin (hereinafter also referred to as "resin") is used. Examples of the thermoplastic resin include polyester resins, polycarbonate resins, acrylic resins, polystyrene resins, etc. Among these, polycarbonate resins and polyester resins are preferred. Among the polyester resins, polyarylate resins are particularly preferred. The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, more preferably 5:10 to 12:10. The content of the fluorine atom-containing resin particles in the charge transport layer is preferably 5% by mass or more and 20% by mass or less, more preferably 7% by mass or more and 10% by mass or less. Further, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, etc. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, boron nitride particles, etc. can be mentioned. The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing each of the above materials and a solvent, forming this coating film on the charge generation layer, and drying it. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Among these solvents, ether solvents or aromatic hydrocarbon solvents are preferred. The film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

[0055] (2) Single-layer type photosensitive layer The single-layer type photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating substance, a charge transporting substance, a resin, and a solvent, forming this coating film on a support, a conductive layer, or an undercoat layer, and drying it. Examples of the charge generating substance, the charge transporting substance, and the resin are the same as those exemplified in the above "(1) Laminated type photosensitive layer".

[0056] <Protective layer> In the present disclosure, a protective layer may be provided on the photosensitive layer. By providing the protective layer, the durability can be improved. When the protective layer is not provided, the charge transport layer or the photosensitive layer becomes the surface layer. When the protective layer is provided, the protective layer becomes the surface layer of the electrophotographic photoreceptor. In this case, the protective layer contains fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the formula (1). The protective layer may be formed as a cured film by polymerizing a composition containing, for example, a monomer having a polymerizable functional group, which is a raw material of the binder material. Examples of the reaction in this case include thermal polymerization reaction, photopolymerization reaction, radiation polymerization reaction, etc. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include isocyanate group, blocked isocyanate group, methylol group, alkylmethylol group, epoxy group, metal alkoxyl group, hydroxy group, amino group, carboxy group, thiol group, carboxylic anhydride group, a group containing a carbon-carbon double bond, etc. Examples of the group containing a carbon-carbon double bond include acryloyl group, methacryloyl group, etc. As the monomer having a polymerizable functional group, a monomer having a charge transport ability may be used.

[0057] Here, the cured product of the monomer having a polymerizable functional group is the binder material of the protective layer. That is, in the present disclosure, the surface layer contains at least any one selected from the binder material, or the binder material and the raw material of the binder material. As the monomer having a polymerizable functional group, it is preferable to use a hole transporting compound having a chain polymerizable functional group. As the hole transporting compound having a chain polymerizable functional group, it is more preferable that it is a compound represented by the following formula (CT-1) or (CT-2).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0058] The content of the polytetrafluoroethylene particles in the protective layer is preferably 5% by mass or more and 40% by mass or less, more preferably 25% by mass or more and 35% by mass or less, based on the total mass of the protective layer.

[0059] The protective layer preferably contains a compound represented by the following formula (3). Also, from the viewpoint of using it as a dispersion medium when preparing the coating liquid for the surface layer, the compound represented by the following formula (3) is preferably a liquid compound.

Chemical formula

[0060] Examples of the compound represented by the formula (3) include methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, 1,1,1,2,3,4,4,5,5,5 - decafluoro - 3 - methoxy - 2 - (trifluoromethyl) pentane, 1,1,2,2 - tetrafluoroethyl - 2,2,2 - trifluoroethyl ether, and the like. Among them, 1,1,2,2 - tetrafluoroethyl - 2,2,2 - trifluoroethyl ether is preferable from the viewpoints of improving dispersibility and suppressing potential fluctuations during repeated use. In the protective layer, the content of the compound represented by the formula (3) is preferably 1 ppm or more and 10 ppm or less from the viewpoint of suppressing potential fluctuations.

[0061] Examples of the method for measuring the content of the compound represented by the formula (3) in the protective layer include a method by GCMS analysis. As the measurement sample, a film sample obtained by scraping off the surface layer on the electrophotographic photoreceptor with a razor or the like is used. By analyzing this measurement sample by GCMS, the content of the compound represented by the formula (3) contained in the surface layer can be measured. As the apparatus used for GCMS analysis, for example, GCMS - QP2000 (manufactured by Shimadzu Corporation) can be used. Also in the examples of the present disclosure, after obtaining a measurement sample by the above method, the content of the compound represented by the formula (3) was measured using the above GCMS apparatus.

[0062] The protective 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, and silicone oils. The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned respective materials and a solvent, forming this coating film on the photosensitive layer, and drying and / or curing it. Examples of the solvent 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 film 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.

[0063] <Surface treatment of the electrophotographic photoreceptor> In the present disclosure, surface treatment of the electrophotographic photoreceptor may be performed. By performing surface treatment, the behavior of the cleaning means (cleaning blade) that contacts the electrophotographic photoreceptor can be made more stable. Examples of the surface treatment method include a method of pressing a mold having convex portions against the surface of the electrophotographic photoreceptor to perform shape transfer, a method of imparting an uneven shape by mechanical polishing, or a method of causing powder to collide with the surface of the electrophotographic photoreceptor to roughen the surface. Thus, by providing concave portions or convex portions in the surface layer of the electrophotographic photoreceptor, the behavior of the cleaning means that contacts the electrophotographic photoreceptor can be made more stable. The concave portions or convex portions may be formed over the entire surface of the electrophotographic photoreceptor, or may be formed on a part of the surface of the electrophotographic photoreceptor. When the concave portions or convex portions are formed on a part of the surface of the electrophotographic photoreceptor, it is preferable that the concave portions or convex portions are formed over the entire contact area with at least the cleaning means (cleaning blade). When forming the concave portions, the concave portions can be formed on the surface of the electrophotographic photoreceptor by pressing a mold having convex portions corresponding to the concave portions against the surface of the electrophotographic photoreceptor and performing shape transfer.

[0064] <Abrasive tools used for mechanical polishing> Mechanical polishing can utilize known means. Generally, a polishing tool is brought into contact with the electrophotographic photoreceptor, and either one or both are relatively moved to polish the surface of the electrophotographic photoreceptor. The polishing tool is a polishing member provided with a layer in which abrasive grains are dispersed in a binder resin on a substrate. Examples of the abrasive grains include particles such as aluminum oxide, chromium oxide, diamond, iron oxide, cerium oxide, corundum, silica, silicon nitride, boron nitride, molybdenum carbide, silicon carbide, tungsten carbide, titanium carbide, and silicon oxide. The particle size of the abrasive grains is preferably 0.01 μm or more and 50 μm or less, and more preferably 1 μm or more and 15 μm or less. If the particle size of the abrasive grains is too small, the polishing force becomes weak, and it becomes difficult to increase the molar fraction ratio of fluorine atom F to carbon atom C, i.e., the F / C ratio, by X-ray photoelectron spectroscopy of the surface layer on the outermost surface of the electrophotographic photoreceptor. These abrasive grains can be used alone or in a mixture of two or more. When mixing two or more types, they may or may not have different materials and particle sizes. As the binder resin for dispersing the abrasive grains used in the polishing tool, known thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, ultraviolet curable resins, visible light curable resins, and antifungal resins can be used. Examples of the thermoplastic resin include vinyl chloride resin, polyamide resin, polyester resin, polycarbonate resin, amino resin, styrene-butadiene copolymer, urethane elastomer, and polyamide-silicone resin. Examples of the thermosetting resin include phenol resin, phenoxy resin, epoxy resin, polyurethane resin, polyester resin, silicone resin, melamine resin, and alkyd resin. Also, an isocyanate-based curing agent may be added to the thermoplastic resin. The film thickness of the layer formed by dispersing the abrasive grains in the binder resin of the polishing tool is preferably 1 μm or more and 100 μm or less. If the film thickness is too thick, film thickness unevenness is likely to occur, and as a result, unevenness in the surface roughness of the workpiece becomes a problem. On the other hand, if the film thickness is too thin, the abrasive grains are likely to fall off. The shape of the base material of the abrasive tool is not particularly limited. In the examples of the present disclosure, a sheet-shaped base material was used to efficiently polish a cylindrical electrophotographic photoreceptor, but other shapes may also be used (hereinafter, the abrasive tool of the present disclosure is also referred to as a "polishing sheet"). The material of the base material of the abrasive tool is not particularly limited either. For example, as the material of the sheet-shaped base material, paper, woven fabric, non-woven fabric, and plastic film can be mentioned. The abrasive tool can be obtained by applying and drying a paint in which abrasive grains, a binder resin, and a solvent capable of dissolving the binder resin are mixed and dispersed on a base material.

[0065] <Polishing device> An example of the polishing device for the electrophotographic photoreceptor of the present disclosure is shown in FIG. 2. FIG. 2 is a device for polishing a cylindrical electrophotographic photoreceptor using a polishing sheet. In FIG. 2, the polishing sheet 2-1 is wound around a hollow shaft 2-6, and a motor (not shown) is arranged so as to apply tension to the polishing sheet 2-1 in a direction opposite 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 the backup roller 2-3 via the guide rollers 2-2a and 2-2b, and the polished polishing sheet 2-1 is wound around the winding means 2-5 by a motor (not shown) via the guide rollers 2-2c and 2-2d. The polishing is performed by constantly pressing the polishing sheet 2-1 against the object to be processed (the electrophotographic photoreceptor before polishing) 2-4. Since the polishing sheet 2-1 is often insulating, it is preferable to use something that contacts the ground or has conductivity at the part where the polishing sheet 2-1 contacts. The feed speed of the polishing sheet 2-1 is preferably in the range of 10 to 1000 mm / min. If the feed amount is small, adhesion of the binder resin to the surface of the polishing sheet 2-1 and, as a result, deep scratches may occur on the surface of the object to be processed 2-4. The object to be processed 2-4 is placed at a position facing the backup roller 2-3 via the polishing sheet 2-1. The backup roller 2-3 is preferably an elastic body from the viewpoint of improving the uniformity of the surface roughness of the object to be processed 2-4. At this time, the object to be processed 2-4 and the backup roller 2-3 are pressed against each other via the polishing sheet 2-1 at a desired set value for a predetermined time, and the surface of the object to be processed 2-4 is polished. The rotation direction of the object to be processed 2-4 may be the same as or opposite to the direction in which the polishing sheet 2-1 is fed. Also, the rotation direction may be changed during polishing. The pressing pressure of the backup roller 2-3 against the object to be processed 2-4 depends on the hardness of the backup roller 2-3 and the polishing time, but is preferably 0.005 to 15 N / m 2 is preferred. The surface roughness of the electrophotographic photoreceptor can be adjusted by appropriately selecting the feed speed of the polishing sheet 2-1, the pressing pressure of the backup roller 2-3, the abrasive grain type of the polishing sheet, the film thickness of the binder resin of the polishing sheet, the thickness of the substrate, etc.

[0066] <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, the following can be mentioned. Surface roughness meters such as the Surf Coater SE3500 type surface roughness measuring instrument manufactured by Kosaka Laboratory Ltd. Non-contact three-dimensional surface measuring machine Micromap 557N manufactured by Hishikawa System Co., Ltd. Microscopes capable of acquiring three-dimensional shapes such as the ultra-depth shape measuring microscope VK-8550 and VK-9000 manufactured by Keyence Corporation. In the present disclosure, among the indicators of surface roughness, the maximum height Rmax in JIS B0601 1982 defined by the Japanese Industrial Standard JIS is used as the polishing depth L (μm). Also, in the present disclosure, the Rmax is measured in advance for the range of the 5 mm square section of the electrophotographic photoreceptor cut out as a specimen for the X-ray photoelectron spectroscopy described later. The measurement is performed arbitrarily at three locations in the range of the 5 mm square of the cut-out electrophotographic photoreceptor, and the average value is adopted as the polishing depth L (μm).

[0067] <Intermediate Transfer Belt for Electrophotography> The surface layer of the intermediate transfer belt of the present disclosure has a perfluoropolyether, a binder material, and a polymer B having a structural unit represented by the formula (2).

[0068] <Base Layer> As shown in FIG. 6, the intermediate transfer belt 30 is composed of two layers: a base layer 31 and a surface layer 32 provided on the outer periphery of the base layer 31. As the material constituting the base layer 31, a resin having mechanical strength and flex resistance as an intermediate transfer belt for an image forming apparatus is preferable. Specific examples of such resins are given below. Polyamide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polysulfone, polyethersulfone, polyphenylsulfide, polybutylene terephthalate, polyetheretherketone, polyvinylidene fluoride, polyvinyl fluoride, polyetheramide copolymer, polyurethane copolymer, polyimide, polyamideimide. The base layer 31 is preferably formed from one of these resins or a mixture thereof. In the base layer 31, a conductive substance can usually be added to impart conductivity. Examples of the conductive substance include carbon-based inorganic conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and inorganic conductive particles such as metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide. The base layer 31 preferably has a volume resistivity adjusted in the range of 1×10 8 [Ω·cm] or more and 1×10 12 [Ω·cm] or less. By setting the volume resistivity of the base layer 31 to 1×10 12 [Ω·cm] or less, a decrease in primary transferability and secondary transferability due to application of a predetermined transfer bias can be more reliably suppressed. Also, by setting the volume resistivity of the base layer 31 to 1×10 8 [Ω·cm] or more, generation of resistance unevenness can be suppressed, and generation of transfer unevenness, image defects, etc. can be more reliably prevented. Further, the base layer 31 preferably has a surface resistivity adjusted to a range of 1×10 8 [Ω / sq] or more and 1×10 14 [Ω / sq] or less. By setting the surface resistivity of the base layer 31 within the above range, it is possible to more reliably reduce image defects caused by peeling discharge when the transfer material separates from the intermediate transfer belt and toner scattering. The thickness of the base layer 31 is preferably 40 μm or more and 200 μm or less in terms of mechanical strength and flex resistance.

[0069] <Surface layer> The surface layer 32 contains a binder resin as a binder material, perfluoropolyether (hereinafter also referred to as PFPE), and a polymer B having a structural unit represented by the above formula (2). The polymer B is a copolymer of an acrylate having a fluoroalkyl group and a methacrylate macromonomer having polymethyl methacrylate in its side chain, having a number average molecular weight of 11,000 or more and 15,000 or less, and a peak top molecular weight of 24,000 or more and 40,000 or less. In addition to the above binder resin, PFPE, and dispersant, the surface layer 32 may contain a photopolymerization initiator, a conductive substance, etc.

[0070] <Binder resin> As the binder resin as a binder material, styrene resin, acrylic resin, methacrylic resin, epoxy resin, polyester resin, polyether resin, silicone resin, polyvinyl butyral resin, and a mixed resin thereof can be used. The binder resin is used to disperse PFPE, ensure adhesion to the base layer 31, and ensure mechanical strength characteristics. Among the above binder resins, a methacrylic resin or an acrylic resin is preferably used because it is possible to favorably disperse PFPE constituting the surface layer 32 of the intermediate transfer belt. Hereinafter, methacrylic resin and acrylic resin are collectively referred to as acrylic resin.

[0071] Examples of the polymerizable monomer for forming the acrylic resin include the following (i) or (ii). It is also possible to use a polymerizable monomer that is commercially available as a paint. (i) At least one acrylate selected from the group consisting of pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, alkyl acrylate, benzyl acrylate, phenyl acrylate, ethylene glycol diacrylate, and bisphenol A diacrylate. (ii) At least one methacrylate selected from the group consisting of pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, alkyl methacrylate, benzyl methacrylate, phenyl methacrylate, ethylene glycol dimethacrylate, and bisphenol A dimethacrylate. Among these, considering rubbing against other members such as a photoreceptor and a cleaning blade, it is preferably hard. For this reason, it is preferable to use a large amount of a bifunctional or higher crosslinkable monomer for the acrylic resin to make it harder.

[0072] In addition, to form an acrylic resin from such a polymerizable monomer, there is a method of adding a photoinitiator and polymerizing it by an electron beam or ultraviolet rays. Examples of the photoinitiator include radical-generating photoinitiators such as benzophenone, thioxanthone-based, benzyldimethylketal, α-hydroxyketone, α-hydroxyalkylphenone, α-aminoketone, α-aminoalkylphenone, monoacylphosphine oxide, bisacylphosphine oxide, hydroxybenzophenone, aminobenzophenone, titanocene-based, oxime ester, and oxyphenylacetic acid ester. The content of the binder resin in the surface layer is preferably 20% by mass or more and 70% by mass or less with respect to the mass of the total solid content of the surface layer 32 in order to give the surface layer excellent strength and to impart excellent toner releasability to the outer surface of the surface layer.

[0073] <PFPE (Perfluoropolyether)> PFPE refers to an oligomer or polymer having perfluoroalkylene ether as a repeating unit. Examples of the repeating unit of perfluoroalkylene ether include repeating units of perfluoromethylene ether, perfluoroethylene ether, and perfluoropropylene ether. As PFPE, for example, those commercially available under the trade names "Demnum" (manufactured by Daikin Industries, Ltd.), "Krytox" (manufactured by DuPont), and Fomblin (manufactured by Solvay Specialty Polymers) can be used. The weight average molecular weight Mw of the PFPE is preferably 1000 or more and 9000 or less from the viewpoint of the transferability of the PFPE to the surface of the intermediate transfer belt. The weight average molecular weight referred to here is a value measured by dissolving PFPE in "Zeolora H" (trade name; manufactured by Nippon Zeon Co., Ltd.) and analyzing the solution with a liquid chromatograph analyzer (manufactured by Shimadzu Corporation). The chemical name of "Zeolora H" is 1,1,2,2,3,3,4-heptafluorocyclopentane. Further, PFPE may have a reactive functional group capable of forming a state of bonding or being close to bonding with the binder resin, and a non-reactive functional group incapable of forming a state of bonding or being close to bonding with the binder resin. When PFPE has the reactive functional group, the compatibility between the binder resin and PFPE becomes good due to the interaction with the binder resin, and it is stably dispersed. For example, when the binder resin is formed by an addition reaction, examples of the reactive functional group that undergoes an addition reaction with the monomer for forming the binder resin include an acrylic group, a methacrylic group, and an oxysilyl group. Examples of commercially available PFPEs having such reactive functional groups include "Fluorolink MD500", "Fluorolink MD700", "Fluorolink 5101X", "Fluorolink 5113X", "Fluorolink AD1700" (all are trade names; manufactured by SOLVAY), and "Optool DAC" (trade name; manufactured by Daikin). Note that "Fluorolink MD500" is a PFPE having a methacrylic group as a functional group, and "Fluorolink AD1700" is a PFPE having an acrylic group as a functional group. When the binder resin is formed by an addition reaction, examples of the monomer that causes an addition reaction with the binder resin-forming monomer and non-reactive functional groups that do not cause an addition reaction include a hydroxyl group, a trifluoromethyl group, or a methyl group. Examples of commercially available PFPEs having such non-reactive functional groups include "Fluorolink D10H", "Fluorolink D4000", "Fomblin Z15" (all are trade names; manufactured by SOLVAY); "Demnum S-20", "Demnum S-65", "Demnum S200" (all are trade names; manufactured by Daikin). Among them, from the viewpoint of further facilitating the transfer of PFPE to the surface of the intermediate transfer belt and further realizing high releasability of the surface of the intermediate transfer belt, it is preferable that the PFPE has non-reactive functional groups. Also, the content of PFPE in the surface layer is preferably 20% by mass or more and 40% by mass or less with respect to the mass of the total solid content of the surface layer. By adjusting the content of PFPE within the above range, even when repeated transfer is performed, PFPE can be supplied from the surface layer of the intermediate transfer belt to the surface of the intermediate transfer belt, and a decrease in the releasability of the surface of the intermediate transfer belt can be suppressed.

[0074] <Conductive agent> It is also preferable that the intermediate transfer belt after forming the surface layer 32 on the base layer 31 shows a similar value for the electrical resistance. Therefore, it is preferable that the surface layer 32 is also semiconductive. That is, the volume resistivity of the intermediate transfer belt is 1×10 8 [Ω·cm] or more and 1×10 12It is preferably adjusted to the range of [[Ω·cm]] or less. Further, the surface resistivity of the intermediate transfer belt is preferably adjusted to the range of 1×10 8 [Ω / □] or more and 1×10 14 [Ω / □] or less. In order to adjust the volume resistivity and surface resistivity of the intermediate transfer belt, it is preferable to contain a conductive agent in the surface layer 32. A conductive agent can be added to the surface layer 32 to impart conductivity. Examples of the conductive agent include carbon-based inorganic conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide. The surface layer 32 contains the binder material and PFPE, and preferably has a matrix-domain structure in the thickness direction thereof, and the average major axis of the domain is 1 nm or more and 60 nm or less.

[0075] <matrix-domain structure> The surface layer 32 has a matrix-domain structure in the thickness direction thereof. PFPE has a very small surface free energy. Therefore, by incorporating PFPE into the surface layer 32 of the intermediate transfer belt, the adhesiveness of toner to the surface of the surface layer 32 can be reduced. By the way, due to the characteristic that PFPE has a very small surface free energy, it easily migrates to the interface between the surface layer 32 and air, that is, the outermost surface side of the surface layer 32. That is, PFPE tends to be unevenly distributed on the surface side of the surface layer 32.

[0076] In this embodiment, PFPE having such characteristics is randomly distributed in the thickness direction of the surface layer 32 by causing PFPE to exist as a domain in the matrix resin constituting the surface layer 32. This indicates that the PFPE exists not only on the outermost surface of the surface layer 32 but also throughout the entire surface layer, and at the same time, it shows a form in which a large amount of PFPE forming domains exists. As a result, even when image output is repeatedly performed and the surface layer 32 of the intermediate transfer belt undergoes various chemical and physical deteriorations and the PFPE on the surface disappears, the PFPE domains existing inside the surface layer 32 are exposed on the surface of the surface layer 32. Thus, PFPE can always be present on the surface of the surface layer 32. Therefore, it is considered that the intermediate transfer belt according to the present invention can maintain good transfer characteristics. This is also supported by the experimental result that, as a result of surface analysis by X-ray photoelectron spectroscopy (XPS) even after the intermediate transfer belt according to this aspect has been subjected to multiple image outputs, the peak derived from PFPE is detected at a value comparable to that in the initial state.

[0077] Also, as described above, the surface layer 32 of the intermediate transfer belt according to this aspect has a matrix-domain structure in the thickness direction. For this reason, the domains containing PFPE are randomly distributed in the thickness direction of the surface layer 32, that is, from the base layer 31 side to the outermost surface side of the surface layer 32. In a surface layer having such a configuration, a part of the domain located on the outermost surface side of the surface layer 32 is exposed on the surface or is exposed at the earliest stage of image formation. As a result, a state in which domains containing PFPE are scattered in the matrix is formed on the surface of the surface layer 32. In this way, on a surface having regions with different adhesiveness to toner, it is difficult for the toner to adhere, which is a preferable form for maintaining good transfer characteristics.

[0078] Furthermore, depending on the components used when forming the surface layer 32, such as the type and combination of the binder material, PFPE, solvent, dispersant, etc. contained in the matrix, a structure may be formed in which voids exist in a part of the PFPE domains exposed on the outermost surface of the surface layer 32.

[0079] In a form where concave shapes are scattered in an island-like manner on the outermost surface due to the existence of such voids, the outermost surface is easily worn away by physical actions such as rubbing with a cleaning blade or paper. As a result, the supply of PFPE from the concave-shaped PFPE domains is promoted, and since the outermost surface is easily worn away, the PFPE domains existing in the thickness direction are likely to appear on the outermost surface, enabling the action of PFPE to be effectively manifested. Also, due to the concave shape, the contact area between the outermost surface and the toner becomes smaller, reducing the adhesion force of the toner to the surface layer 32. With these mainly three actions, the structure in which voids exist in a part of the PFPE domains exposed on the outermost surface of the surface layer can be said to be a preferable form as a structure for maintaining good transfer characteristics. The effects due to the shape described here can also be manifested by controlling the shape of the outermost surface through physical surface processing such as nanoimprinting or wrapping treatment.

[0080] In the matrix-domain structure, the average major axis of the domain is 1 nm or more and 60 nm or less. By setting the average major axis of the domain to 1 nm or more, a matrix-domain structure is formed, which can reduce the adhesion to the toner over a long period and maintain good transfer characteristics. Also, by setting the average major axis of the domain to 60 nm or less, it becomes possible to maintain the surface glossiness over a long period. The average major axis of the domain can be measured by the method described in the examples.

[0081] Also, it is difficult to obtain the effects exhibited by the intermediate transfer belt according to this aspect even if polytetrafluoroethylene particles, which are the same fluorine compound, are simply dispersed in the surface layer 32 of the intermediate transfer belt. This is also considered to be a reason why the effects are manifested due to the action of PFPE. Furthermore, although it is preferable that the domain consists substantially only of PFPE, within the range where the effects exhibited by the intermediate transfer belt according to this aspect are manifested, chemical species other than PFPE may exist in the domain in addition to PFPE. Also, additives compatible with PFPE may be added for the purpose of adjusting other characteristics. Furthermore, even when the inside of the domain is not completely filled with PFPE and voids exist, the same effects can be manifested. The domain containing PFPE is phase-separated from the matrix containing the binder material. However, even when generally phase-separated, the component compositions of the matrix and the domain are not strict. Even in the case of a phase-separated matrix and domain with a distinct interface, each phase may contain a trace amount of the components of the other phase. Also, academically, it is said that an intermediate composition exists at the interface within a very narrow width of around 10 nm. In the present invention, the presence or absence of the matrix-domain structure can be grasped by cutting out the intermediate transfer belt and observing a cross-section in the thickness direction of the surface layer 32 of the intermediate transfer belt with a scanning electron microscope (SEM).

[0082] On the other hand, the surface layer 32 where the matrix-domain structure is observed in the cross-section in the thickness direction is likely to form a state in which regions containing PFPE are scattered in an island-like manner on the outermost surface as described above. Therefore, when observing the outermost surface of the surface layer 32 with an SEM, a state in which regions containing PFPE are scattered in an island-like manner is often observed. Regarding the domain containing PFPE, it can be identified by detecting it with elemental analysis methods such as energy dispersive X-ray analysis (EDX), TOF-SIMS, and Auger spectroscopy. For example, when the domain in the intermediate transfer belt was subjected to elemental analysis by EDX, the fluorine element was detected, and it was identified that the domain was a domain containing PFPE. Also, with TOF-SIMS, fragments of the fluorocarbon ether structure derived from PFPE could be observed from the domain.

[0083] <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 a charging means, a developing means, a transferring means, and a cleaning means, and is detachable from the main body of the electrophotographic apparatus. Further, the electrophotographic apparatus is characterized by having the electrophotographic photoreceptor, a charging means, an exposure means, a developing means, and a transferring means described so far.

[0084] FIG. 3 shows an example of a 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 about the axis 202 in the direction of the arrow at a predetermined peripheral speed (process speed). The surface of the electrophotographic photoreceptor 201 is charged to a predetermined positive or negative 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 a corona charging method, a proximity charging method, and an injection charging method may also be employed. 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 whose intensity is 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. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 201 is developed (normal development or reversal development) with toner on the developing member 213 accommodated 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 having a polarity opposite to the charge held by the toner is applied to the transfer means 206 from a bias power supply (not shown). Further, when the transfer material 207 is paper, the transfer material 207 is taken out from a 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. The transfer material 207 from which the toner image has been transferred from the electrophotographic photoreceptor 201 is separated from the surface of the electrophotographic photoreceptor 201 and conveyed to the fixing means 208, and is printed out outside the electrophotographic apparatus as an image formation (print, copy) by undergoing the fixing process of the toner image. The electrophotographic apparatus may have a cleaning means 209 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 201 after transfer. Further, instead of providing a separate cleaning means, a so-called cleanerless system for removing the deposits with a developing means or the like may be used. Among the components selected from the electrophotographic photoreceptor 201, the charging means 203, the developing means 205, and the cleaning means 209, etc., a plurality of components can be housed in a container and integrally supported to form a process cartridge. Further, it can be configured to be detachable from the main body of the electrophotographic apparatus.For example, it is configured as follows. At least one selected from the charging means 203, the developing means 205, and the cleaning means 209 is integrally supported together with the electrophotographic photoreceptor 201 and made into a cartridge. By using guiding means 212 such as rails of the main body of the electrophotographic apparatus, it can be made into a process cartridge 211 that is detachable from the main body of the electrophotographic apparatus. The electrophotographic apparatus may have a discharging mechanism that discharges the surface of the electrophotographic photoreceptor 201 by pre-exposure light 210 from a pre-exposure means (not shown). Also, guiding means 212 such as rails may be provided to attach and detach the process cartridge 211 to and from the main body of the electrophotographic apparatus. The electrophotographic apparatus according to the present disclosure is characterized by having an electrophotographic photoreceptor 201, and charging means 203, an exposure means, developing means 205, and transfer means 206.

[0085] Further, FIG. 4 shows an example of the schematic configuration of a process cartridge including the electrophotographic photoreceptor of the present disclosure, and FIG. 5 shows an example of the schematic configuration of an electrophotographic apparatus having the process cartridge of FIG. 4. In FIG. 4, the cylindrical electrophotographic photoreceptor 1 is rotationally driven at a predetermined peripheral speed in the direction of the arrow. The peripheral surface of the rotationally driven electrophotographic photoreceptor 1 is uniformly charged to a positive or negative predetermined potential by the charging means 2. Next, the peripheral surface of the charged 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 target image is sequentially formed on the peripheral surface of the electrophotographic photoreceptor 1. As the voltage applied to the charging means (charging roller, etc.) 2, either a voltage obtained by superimposing an AC component on a DC component or a voltage of only a DC component may be used. The electrostatic latent image formed on the peripheral surface of the electrophotographic photoreceptor 1 is developed by toner contained in the developer of the developing means 4 to become a toner image. Next, the toner image formed and supported on the peripheral surface of the electrophotographic photoreceptor 1 is sequentially transferred to a transfer material (such as paper or an intermediate transfer body) 6 by a 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 the surface of the electrophotographic photoreceptor 1 after toner image transfer is discharged by pre-exposure light 7 from pre-exposure means (not shown), the remaining transferred toner is removed by cleaning means 8 to make the surface clean, and the electrophotographic photoreceptor 1 is repeatedly used for image formation. Note that the pre-exposure means may be before or after the cleaning step, and the pre-exposure means is not necessarily required. The electrophotographic photoreceptor 1 may be mounted in an electrophotographic apparatus such as a copying machine or a laser beam printer. Further, among the components such as the electrophotographic photoreceptor 1, the charging means 2, the developing means 4, and the cleaning means 8, a process cartridge 9 configured by housing a plurality of them in a container and supporting them integrally may be configured to be detachable from the main body of the electrophotographic apparatus. In FIG. 4, the electrophotographic photoreceptor 1, the charging means 2, the developing means 4, and the cleaning means 8 are integrally supported and are shown as a process cartridge 9 that is detachable from the main body of the electrophotographic apparatus.

[0086] Next, an electrophotographic apparatus including the electrophotographic photoreceptor of the present disclosure will be described. An example of the configuration of the electrophotographic apparatus of the present disclosure is shown in FIG. 5. Process cartridges 17 for yellow, 18 for magenta, 19 for cyan, and 20 for black, corresponding to yellow, magenta, cyan, and black colors respectively, are juxtaposed along the intermediate transfer body 10. The diameter, constituent material, developer, charging method, and other means of the electrophotographic photoreceptor do not necessarily have to be unified for each color. When the image formation operation starts, toner images of each color are sequentially superimposed on the intermediate transfer body 10 according to the above-described image formation process. In parallel, the transfer paper 11 is fed out from the paper feed tray 13 by the paper feed path 12 and is fed to the secondary transfer means 14 in synchronization with the rotation operation of the intermediate transfer body. By the transfer bias from the secondary transfer means 14, the toner image on the intermediate transfer body 10 is transferred to the transfer paper 11. The toner image transferred onto the transfer paper 11 is conveyed along the paper feed path 12, fixed onto the transfer paper by the fixing means 15, and discharged from the paper discharge unit 16.

[0087] The electrophotographic photoreceptor of the present disclosure can be used in laser beam printers, LED printers, copiers, facsimiles, and multifunction machines thereof.

Example

[0088] Hereinafter, the present disclosure will be described in more detail using examples and comparative examples, but it is not limited thereto. In the description of the following examples, "parts" means mass basis unless otherwise specified.

[0089] <Synthesis of Polymer A having a structural unit represented by Formula (1) and Polymer B having a structural unit represented by Formula (2)> In the present disclosure, Polymer A having a structural unit represented by the above Formula (1) (hereinafter, also referred to as "graft copolymer A") and Polymer B having a structural unit represented by Formula (2) (hereinafter, also referred to as "graft copolymer B") were synthesized as follows. Note that the acrylate compound and macromonomer compound used in the following synthesis examples can be produced, for example, by referring to JP-A-2009-104145.

[0090] (Graft copolymer A-1) 3.31 parts of 1H,1H,2H,2H-perfluorohexyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Corporation), 180 parts of a macromonomer represented by the following formula (M-1) (number average molecular weight 6,000), 14.18 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) (trade name: OTAZO-15, manufactured by Otsuka Chemical Co., Ltd.), and 900 parts of n-butyl acetate were mixed in a glass flask equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, constant temperature bath, and thermometer at 20 °C under a nitrogen atmosphere for 30 minutes, and then the reaction solution was heated to 85 to 90 °C and reacted for 5 hours. The reaction was stopped by ice cooling, and 4500 parts of 2-propanol was added to obtain a precipitate. This precipitate was washed with a mixed solvent of n-butyl acetate:2-propanol = 1:5 and dried at 80 °C under a reduced pressure of 1325 Pa or less for 3 hours to obtain graft copolymer A-1. [Chemistry]

[0091] (Graft copolymer A-2) A graft copolymer A-2 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 2.81 parts of 1H,1H,2H,2H-perfluoropentyl methacrylate.

[0092] (Graft copolymer A-3) A graft copolymer A-3 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.81 parts of 1H,1H,2H,2H-perfluorooctyl methacrylate.

[0093] (Graft copolymer A-4) A graft copolymer A-4 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 70.88 parts.

[0094] (Graft copolymer A-5) A graft copolymer A-5 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 42.53 parts.

[0095] (Graft copolymer A-6) A graft copolymer A-6 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 17.72 parts.

[0096] (Graft copolymer A-7) A graft copolymer A-7 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 11.70 parts.

[0097] (Graft copolymer A-8) A graft copolymer A-8 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 8.51 parts.

[0098] (Graft copolymer A-9) A graft copolymer A-9 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 7.80 parts.

[0099] (Graft copolymer A-10) A graft copolymer A-10 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 6.38 parts.

[0100] (Graft copolymer A-11) A graft copolymer A-11 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of the macromonomer represented by the formula (M-1) used was changed to 1440 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 88.60 parts, and the amount of n-butyl acetate used was changed to 4500 parts.

[0101] (Graft copolymer A-12) A graft copolymer A-12 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of the macromonomer represented by the formula (M-1) used was changed to 1140 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 70.88 parts, and the amount of n-butyl acetate used was changed to 4200 parts.

[0102] (Graft copolymer A-13) The graft copolymer A-13 was obtained in the same manner as in the synthesis example of the graft copolymer A-1, except that the amount of the macromonomer represented by the formula (M-1) was changed to 240 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) was changed to 17.72 parts, and the amount of n-butyl acetate was changed to 1200 parts.

[0103] (Graft copolymer A-14) The graft copolymer A-14 was obtained in the same manner as in the synthesis example of the graft copolymer A-1, except that the amount of 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 2.98 parts, the amount of the macromonomer represented by the formula (M-1) was changed to 66 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) was changed to 7.09 parts, and the amount of n-butyl acetate was changed to 500 parts.

[0104] (Graft copolymer A-15) The graft copolymer A-15 was obtained in the same manner as in the synthesis example of the graft copolymer A-1, except that the amount of the macromonomer represented by the formula (M-1) was changed to 60 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) was changed to 7.09 parts, and the amount of n-butyl acetate was changed to 500 parts.

[0105] (Graft copolymer A-16) The graft copolymer A-16 was obtained in the same manner as in the synthesis example of the graft copolymer A-1, except that the amount of 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.64 parts, the amount of the macromonomer represented by the formula (M-1) was changed to 54 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) was changed to 7.09 parts, and the amount of n-butyl acetate was changed to 500 parts.

[0106] (Graft copolymer B-1) A compound was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate. Preparation was carried out using a preparative HPLC apparatus to obtain graft copolymer B-1.

[0107] (Graft copolymer B-2) A compound was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 2.81 parts of 1H,1H,2H,2H-perfluoropentyl acrylate. Preparation was carried out using a preparative HPLC apparatus to obtain graft copolymer B-2.

[0108] (Graft copolymer B-3) A compound was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.81 parts of 1H,1H,2H,2H-perfluoroheptyl acrylate. Preparation was carried out using a preparative HPLC apparatus to obtain graft copolymer B-3.

[0109] (Graft copolymer B-4) A compound was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate. Preparation was carried out using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-4.

[0110] (Graft copolymer B-5) A compound was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate. Preparation was carried out using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-5.

[0111] (Graft copolymer B-6) A compound obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate, was prepared using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-6.

[0112] (Graft copolymer B-7) A compound obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate, was prepared using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-7.

[0113] (Graft copolymer B-8) A compound obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate, was prepared using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-8.

[0114] (Graft copolymer B-9) A compound obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 1H,1H,2H,2H-perfluorohexyl methacrylate was changed to 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate, was prepared using a preparative HPLC apparatus at an elution time different from that of graft copolymer B-1 to obtain graft copolymer B-9.

[0115] The obtained graft copolymers A-1 to A-16 were subjected to GPC measurement by the above method to calculate the weight average molecular weight. The results are shown in Table 4.

Table 4

[0116] The obtained graft copolymers B-1 to B-9 were measured by GPC by the above method, and the number average molecular weight and the peak top molecular weight were calculated. The results are shown in Table 5.

Table 5

[0117] <Fabrication of Electrophotographic Photoreceptor> 〔Photoreceptor 1〕 (Support 1) As the support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30.6 mm, length 370 mm, wall thickness 1 mm) that had been machined by cutting was used. Ultrasonic cleaning was performed in a cleaning solution containing a detergent (trade name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water. Subsequently, after flushing the cleaning solution away, ultrasonic cleaning was further performed in pure water for degreasing treatment, and this was designated as Support 1.

[0118] (Undercoat layer 1) 100 parts of zinc oxide particles (specific surface area: 19 m 2 / g, powder resistance: 4.7×10 6 Ω·cm) were stirred and mixed with 500 parts of toluene. To this, 0.8 part of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 6 hours. Thereafter, toluene was distilled off under reduced pressure and dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles A. Subsequently, 15 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol 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 part of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and this was dispersed for 3 hours in an atmosphere of 23 ± 3°C using a sand mill apparatus with glass beads having a diameter of 0.8 mm. After the dispersion treatment, 0.01 part of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (former: Toray Dow Corning Silicone Co., Ltd.)) and 5.6 parts of crosslinked polymethyl methacrylate (PMMA) particles (trade name: Tech Polymer SSX-103, manufactured by Sekisui Chemical Products Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer. The obtained coating solution for the undercoat layer was dip-coated on the support 1 to form a coating film, and the coating film was dried at 160°C for 30 minutes to form an undercoat layer 1 with a film thickness of 18 μm.

[0119] (Charge generation layer 1) 4 parts of crystalline hydroxygallium phthalocyanine crystals (charge generating substance) 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 part of the compound represented by the following formula (E) were added to a solution obtained by dissolving 2 parts of polyvinyl butyral (trade name: Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. Thereafter, it was dispersed for 1 hour in an atmosphere of 23 ± 3°C using a sand mill with glass beads having a diameter of 1 mm, and after the dispersion treatment, 100 parts of ethyl acetate was added to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was dip-coated on the undercoat layer 1, and the obtained coating film was dried at 90°C for 10 minutes to form a charge generation layer 1 with a film thickness of 0.15 μm.

Chemical formula

[0120] (Charge transport layer 1) 60 parts of the compound represented by the following formula (F), 30 parts of the compound represented by the following formula (G), 10 parts of the compound represented by the following formula (H), 100 parts of bisphenol Z type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation), and 0.2 part of polycarbonate having a structural unit represented by the following formula (I) (viscosity average molecular weight Mv: 20,000) were dissolved in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane to prepare a coating solution for the charge transport layer. This coating solution for the charge transport layer was dip-coated on the above-mentioned charge generation layer 1 to form a coating film, and the obtained coating film was dried at 115 °C for 50 minutes to form a charge transport layer 1 having a film thickness of 18 μm. [Chemical formula] [Chemical formula] [Chemical formula] [Chemical formula] (In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0121] (Protective layer 1) 2.8 parts of the above-mentioned graft copolymer A-1 was dissolved in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) and 100 parts of 1-propanol to prepare a dispersant solution. 40 parts of commercially available polytetrafluoroethylene resin particles (average primary particle size: 210 nm, average circularity: 0.85) were added to the obtained dispersant solution. Then, it was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics Corporation, USA) to obtain a polytetrafluoroethylene resin particle dispersion. To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of a hole transporting compound represented by the following formula (B), 21.9 parts of a compound represented by the following formula (C), and 100 parts of 1-propanol were added. Then, filtration was performed using a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating solution for the protective layer).

Chemical formula

Chemical formula

[0122] <Surface processing of the electrophotographic photoreceptor> (Polishing of the electrophotographic photoreceptor before surface polishing) The surface of the electrophotographic photoreceptor before forming the surface shape was polished. The polishing was performed using the polishing apparatus shown in Figure 2 under the following conditions. Feed speed of the polishing sheet; 400 mm / min Rotation speed of the electrophotographic photoreceptor; 450 rpm Pushing-in of the electrophotographic photoreceptor to the backup roller; 3.5 mm Rotation direction of the polishing sheet and the electrophotographic photoreceptor; with Backup roller; outer diameter 100 mm, Asker C hardness 25 The polishing sheet A to be attached to the polishing device was prepared by mixing the polishing abrasive grains used in GC3000 and GC2000 manufactured by Riken Korundum Co., Ltd. GC3000 (polishing sheet surface roughness Ra 0.83 μm) GC2000 (polishing sheet surface roughness Ra 1.45 μm) Polishing sheet A (polishing sheet surface roughness Ra 1.12 μm) The polishing time using the polishing sheet A was set to 20 seconds.

[0123] (Measurement of polishing depth L (μm)) Regarding the electrophotographic photoreceptor after polishing, the maximum height Rmax was measured in accordance with JIS B 0601 1982 using a surface roughness measuring instrument Surfcodar SE3500 type manufactured by Kosaka Laboratory Ltd. The measurement conditions were set as follows. The measurement was carried out arbitrarily at three locations within a 5 mm square range of the electrophotographic photoreceptor after polishing, and the average value was adopted as the polishing depth L (μm). The polishing depth L of the electrophotographic photoreceptor after surface polishing was 0.75 μm. Also, in Examples 1-2 to 1-25 described later, the polishing depth L of the electrophotographic photoreceptor subjected to surface processing was all 0.75 μm. (Measurement conditions) Detector: R2μm Stylus: Diamond needle with 0.7 mN Filter: 2CR Cutoff value: 0.08 mm Measurement length: 2.5 mm Feed speed: 0.1 mm

[0124] [Electrophotographic photoreceptors 2 to 16, 23] In the formation of the protective layer, electrophotographic photoreceptors 2 to 16 and 23 were produced in the same manner as the production of electrophotographic photoreceptor 1, except that the graft copolymer A-1 was changed to the graft copolymers shown in Table 6.

[0125] [Electrophotographic photoreceptors 17 to 20] In the formation of the protective layer, electrophotographic photoreceptors 17 to 20 were produced in the same manner as the production of electrophotographic photoreceptor 1, except that the graft copolymer A-1 was changed to the parts by mass shown in Table 6.

[0126] [Electrophotographic photoreceptor 21] In the formation of the protective layer, an electrophotographic photoreceptor 21 was produced in the same manner as the production of the electrophotographic photoreceptor 1, except that the protective layer 2 was changed to be formed as follows.

[0127] (Protective layer 2) 2.80 parts of the above graft copolymer A-1 was dissolved in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) and 100 parts of 1-propanol to prepare a dispersant solution. 40 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average roundness 0.85) were added to the obtained dispersant solution. Then, it was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics Corp., USA) to obtain a polytetrafluoroethylene resin particle dispersion. 97.3 parts of the hole transporting compound represented by the formula (B) and 100 parts of 1-propanol were added to the obtained polytetrafluoroethylene resin particle dispersion. Then, filtration was performed with a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating solution for protective layer). This coating solution for 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, heat treatment was performed for 15 seconds under the condition that the temperature of the coating film was 135 °C in a nitrogen atmosphere. The oxygen concentration from the electron beam irradiation to the 15-second heat treatment was 15 ppm. Next, in the air, it was naturally cooled until the temperature of the coating film reached 25 °C, and then heat treatment was performed for 1 hour under the condition that the coating film reached 105 °C to form a surface layer (protective layer 2) with a film thickness of 5 μm.

[0128] [Electrophotographic photoreceptor 22] In the formation of the protective layer, an electrophotographic photoreceptor 22 was produced in the same manner as in the production of the electrophotographic photoreceptor 1, except that the protective layer 3 was formed as follows.

[0129] (Protective layer 3) 4.80 parts of the aforementioned graft copolymer A-1 was dissolved in 80 parts of tetrahydrofuran to prepare a dispersant solution. To the obtained dispersant solution, 24 parts of polytetrafluoroethylene resin particles (average primary particle diameter 210 nm, average roundness 0.85) were added. Then, it was passed through a high-pressure homogenizer (trade name: Microfluidizer M-110EH, manufactured by Microfluidics Corporation, USA) to obtain a polytetrafluoroethylene resin particle dispersion. To the obtained polytetrafluoroethylene resin particle dispersion, 115 parts of a hole-transporting compound represented by the following formula (C-26), 8.00 parts of a triazine compound represented by the following formula (A-15), 2.17 parts of dodecylbenzenesulfonic acid, and 0.29 part of an antioxidant were added. [Chemical formula] [Chemical formula] Thereafter, filtration was performed using a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating solution for the protective layer). This 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 absorbed dose of 15 kGy in a nitrogen atmosphere. Thereafter, heat treatment was performed for 15 seconds under the condition that the temperature of the coating film reached 135 °C in a nitrogen atmosphere. The oxygen concentration from the electron beam irradiation to the 15-second heat treatment was 15 ppm. Next, in the air, it was naturally cooled until the temperature of the coating film reached 25 °C, and then heat treatment was performed for 1 hour under the condition that the coating film reached 105 °C to form a surface layer (protective layer 3) with a film thickness of 5 μm.

[0130] [Table 6]

[0131] <Production of Intermediate Transfer Belt> 〔Preparation of Dispersion for Forming Surface Layer〕 The following materials were mixed and dispersed using a stirring homogenizer (manufactured by AS ONE Corporation), and then dispersed using a dispersion device (product name: Nanomizer; manufactured by Yoshida Kikai Kogyo Co., Ltd.) to obtain a dispersion for forming a surface layer. · 7.0 parts by mass of dipentaerythritol hexaacrylate (DPHA) · 15.0 parts by mass of pentaerythritol tetraacrylate (PETTA) · 4.4 parts by mass of pentaerythritol triacrylate (PETA) · 26.4 parts by mass of methyl ethyl ketone · 4.5 parts by mass of antimony-doped tin oxide fine particles (product name: SN-100P; manufactured by Ishihara Sangyo Co., Ltd.) · 2.0 parts by mass of photoinitiator 1 (product name: OMNIRAD4; IGM Resins) · 14.8 parts by mass of PFPE1 (product name: Fluorolink MD700 (manufactured by Solvay Specialty Polymers)) · 25.9 parts by mass of graft copolymer B-1

[0132] 〔Intermediate Transfer Belt 1〕 An intermediate transfer belt made of polyimide, which is equipped in a color electrophotographic apparatus (product name: iRC2620; manufactured by Canon Inc.), was used as the base layer 31. The dispersion prepared above was applied to the outer peripheral surface of this base layer 31, and dried at a temperature of 70 °C for 3 minutes to form a coating film of the dispersion for forming a surface layer. Next, the coating film was irradiated with ultraviolet rays of 500 mJ / cm 2 and cured using a UV treatment apparatus (manufactured by Eye Graphics Co., Ltd.) to form a surface layer with a film thickness of 4 μm, thereby obtaining the intermediate transfer belt 1. Table 7 shows the addition amount of the perfluoropolyether used, the type of dispersant, and the addition amount. In Table 7, the addition amounts of the perfluoropolyether and the dispersant were described as the contents in the total solid content. The total solid content was calculated by excluding methyl ethyl ketone, which is a solvent, and the solvent content of the dispersant from the components of the composition.

[0133] 〔Intermediate transfer belts 2 to 9, 13〕 In the preparation of the dispersion for forming the surface layer, an intermediate transfer belt was produced in the same manner as in the production of intermediate transfer belt 1, except that the graft copolymer B-1 was changed to the graft copolymer shown in Table 7.

[0134] 〔Intermediate transfer belts 10 to 12〕 In the preparation of the dispersion for forming the surface layer, an intermediate transfer belt was produced in the same manner as in the production of intermediate transfer belt 1, except that the addition amount of the graft copolymer B-1 was changed to the addition amount shown in Table 7.

[0135]

Table 7

[0136] <Examples 1 to 37, Comparative Examples 1, 2> The obtained electrophotographic photoreceptors 1 to 23 and intermediate transfer belts 1 to 13 were combined as shown in Table 8 to form Examples 1 to 37 and Comparative Examples 1 and 2, and initial image evaluation, drum discoloration evaluation after long-term stop, and image evaluation after long-term stop were performed.

[0137]

Table 8

[0138] <Evaluation> In the following evaluation, Evaluation Device 1 and Evaluation Device 2 were used.

[0139] 〔Evaluation Device 1〕 The produced electrophotographic photoreceptor and intermediate transfer belt were mounted on an imagePRESS C800 (trade name), which is a copying machine manufactured by Canon Inc., in the combination shown in Table 8 for evaluation. Specifically, the evaluation apparatus was installed in a normal temperature and humidity environment of 23°C and 50% RH. The fabricated electrophotographic photoreceptor was attached to the process cartridge for magenta, and then attached to the station of the magenta process cartridge for evaluation.

[0140] 〔Evaluation Apparatus 2〕 The fabricated electrophotographic photoreceptor and the intermediate transfer belt were attached to a modified model of imagePRESS C800 (trade name), which is a copying machine manufactured by Canon Inc., for evaluation. The charging means of the modified model is a charging means that applies a voltage obtained by superimposing an AC voltage on a DC voltage to a roller-type contact charging member (charging roller), and the exposure means is an exposure means using a laser image exposure method (wavelength 680 nm). Specifically, the evaluation apparatus was installed in a high temperature and humidity environment of 30°C and 80% RH. The fabricated electrophotographic photoreceptor was attached to the process cartridge for magenta, and then attached to the station of the magenta process cartridge for evaluation.

[0141] (Initial Image Evaluation) The image evaluation was performed using the above-described evaluation apparatus 1. Using A4-sized glossy paper, a solid white image was output, and the number of image defects due to dispersion defects, that is, the number of black spots, included in the area corresponding to one circumference of the electrophotographic photoreceptor in the output image was visually evaluated according to the following evaluation ranks. The area corresponding to one circumference of the electrophotographic photoreceptor is a rectangular area with a length of 297 mm, which is the long side length of A4 paper, and a width of 94.2 mm, which is the circumference of the electrophotographic photoreceptor. In the present disclosure, ranks A, B, C, and D are the levels at which the effects of the present disclosure are obtained, and among them, rank A is determined to be an excellent level. On the other hand, rank E is determined to be the level at which the effects of the present disclosure are not obtained. Rank A: No black spots Rank B: 1 or more and 3 or less black spots with a diameter of less than 1.5 mm, and no black spots with a diameter of 1.5 mm or more Rank C: 1 or more and 3 or less black spots with a diameter of less than 1.5 mm, and 1 or more and 2 or less black spots with a diameter of 1.5 mm or more Rank D: There are 4 or more and 5 or less black spots with a diameter of less than 1.5 mm, and 2 or less black spots with a diameter of 1.5 mm or more Rank E: There are 6 or more black spots with a diameter of less than 1.5 mm, or 3 or more black spots with a diameter of 1.5 mm or more Evaluation was conducted in this manner. The evaluation results of Examples 1 to 37 and Comparative Examples 1 and 2 are shown in Table 9.

[0142] (Measurement of average major axis of domain) The average major axis of the domain was measured by observing the cross-section of the surface layer 32 of the intermediate transfer belt using a scanning electron microscope (S-4800 manufactured by Hitachi High-Tech Corporation). First, as a sample, a cross-section of the surface layer 32 of the intermediate transfer belt cut out by a microtome (manufactured by Leica Microsystems GmbH, product name: EM UC7) was used. At this time, a cross-section SEM image in which at least 1 or more domains could be confirmed per unit area of 15 μm when the cross-section was magnified 20,000 times was used. When the number of domains was 10 or less, the major axes of all domains in the field of view were measured. When the number of domains exceeded 10, 10 domains were randomly selected and the major axes of the domains were measured. This operation was repeated 10 times for different positions of the cross-section, and the calculated average value of the major axes of a total of 100 domains measured in 10 cross-section SEM images was calculated. The obtained calculated average value was used as the average major axis of the domain in each of the following Examples and Comparative Examples. 2

[0143] (Evaluation of drum discoloration after long-term stop) The evaluation of drum discoloration after long-term stop was carried out using the above-described evaluation apparatus 2. The cartridge equipped with the produced electrophotographic photoreceptor and the intermediate transfer belt were attached to the evaluation apparatus, and after being stored for 2 months in a high-temperature and high-humidity environment at a temperature of 30°C and a relative humidity of 80%RH while stopped, the discoloration of the portion in contact with the intermediate transfer belt on the surface of the electrophotographic photoreceptor was evaluated according to the following evaluation ranks. Rank A: No discoloration is observed at all. Rank B: Almost no discoloration is observed. Rank C: Discoloration has occurred, but it is within the range of 50% or less of the portion in contact with the intermediate transfer belt.​ Rank D: Discoloration is observed. In addition, in the present disclosure, it was determined that ranks A, B, and C are the levels at which the effects of the present disclosure are obtained, and among them, rank A is an excellent level. On the other hand, rank D was determined to be the level at which the effects of the present disclosure are not obtained.

[0144] (Image evaluation after long-term stop) The image evaluation after long-term stop was performed using the above-described evaluation apparatus 2. The cartridge equipped with the produced electrophotographic photoreceptor and the intermediate transfer belt were attached to the evaluation apparatus, and after being stored for 2 months in a high-temperature and high-humidity environment at a temperature of 30 °C and a relative humidity of 80% RH while stopped, image formation was performed. At this time, the initial image before storage in the high-temperature and high-humidity environment was visually observed and compared, and evaluated based on the following criteria. Rank A: No deterioration in image quality due to transfer failure is observed. Rank B: Almost no deterioration in image quality due to transfer failure is observed. Rank C: Deterioration in image quality due to transfer failure occurs, but it is 50% or less of the printed surface. Rank D: Deterioration in image quality due to transfer failure occurs over the entire surface. In addition, in the present disclosure, it was determined that ranks A, B, and C are the levels at which the effects of the present disclosure are obtained, and among them, rank A is an excellent level. On the other hand, rank D was determined to be the level at which the effects of the present disclosure are not obtained.

[0145] Evaluation was performed in this way. The evaluation results of Examples 1 to 37 and Comparative Examples 1 and 2 are shown in Table 9.

Table 9

[0146] The disclosure of this embodiment includes the following configurations. (Configuration 1) An electrophotographic apparatus having an electrophotographic photoreceptor and an intermediate transfer belt that can contact the electrophotographic photoreceptor, wherein the electrophotographic photoreceptor polytetrafluoroethylene particles, and An adhesive material, a polymer A having a structural unit having a perfluoroalkyl group, and having a surface layer containing the intermediate transfer belt a perfluoropolyether, an adhesive material, a polymer B having a structural unit having a perfluoroalkyl group, and having a surface layer containing the polymer A has, as the structural unit having a perfluoroalkyl group, a structural unit represented by the following formula (1), the polymer B has, as the structural unit having a perfluoroalkyl group, a structural unit represented by the following formula (2), An electrophotographic apparatus characterized by the above.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Description of Reference Numerals

[0147] 101 Support 102 Undercoat layer 103 Charge generation layer 104 Charge transport layer 105 Surface layer (protective layer)

Claims

1. An electrophotographic apparatus having an electrophotographic photosensitive member and an intermediate transfer belt that can contact the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has a surface layer containing polytetrafluoroethylene particles, a binder material, and a polymer A having a structural unit having a perfluoroalkyl group, and the intermediate transfer belt has a surface layer containing a perfluoropolyether, a binder material, and a polymer B having a structural unit having a perfluoroalkyl group, the polymer A has a structural unit represented by the following formula (1) as the structural unit having a perfluoroalkyl group, the polymer B has a structural unit represented by the following formula (2) as the structural unit having a perfluoroalkyl group, an electrophotographic apparatus characterized by the above. (In formula (1), 【Chemical 1】 In formula (2), R １１ represents a single bond or an alkylene group having 1 to 3 carbon atoms, Rf １ represents a perfluoroalkyl group having 1 to 5 carbon atoms.) 【Chemical Formula 2】

2. R １２ represents a single bond or an alkylene group having 1 to 3 carbon atoms, Rf ２ represents a perfluoroalkyl group having 1 to 5 carbon atoms. When the mass of the structural unit having a perfluoroalkyl group in the polymer A is MTA and the mass of the structural unit represented by the formula (1) in the polymer A is M1A, the following formula (i) is satisfied, 0.5 < M1A / MTA ≦ 1.0... (i) When the mass of the structural unit having a perfluoroalkyl group in the polymer B is MTB and the mass of the structural unit represented by the formula (2) in the polymer B is M2B, the following formula (ii) is satisfied, 0.5 < M2B / MTB ≦ 1.0... (ii) The electrophotographic apparatus according to claim 1.

3.

4. Rf in the formula (1) above １ The electrophotographic apparatus according to claim 1, wherein the number of carbon atoms of is 2 or more and 4 or less.

5. Rf in the formula (2) above ２ The electrophotographic apparatus according to claim 1, wherein the number of carbon atoms of is 2 or more and 4 or less. The electrophotographic apparatus according to claim 1, wherein the weight average molecular weight of the polymer A is 16,000 or more and 300,000 or less.

6. The electrophotographic apparatus according to claim 1, wherein the content of the structural unit represented by the formula (1) in the polymer A is 5 to 50% by number based on all the structural units in the polymer A.

7. The electrophotographic apparatus according to claim 1, wherein the content of the polymer A in the surface layer of the electrophotographic photosensitive member is 2 to 10% by mass based on the mass of the polytetrafluoroethylene particles in the surface layer of the electrophotographic photosensitive member.

8. The electrophotographic apparatus according to claim 1, wherein the polymer A further has a structural unit represented by the following formula (M). (In formula (M), [Chemical Formula 3] m is an integer of 25 or more and 150 or less.) Y Ａ１ represents an unsubstituted alkylene group, Y Ｂ represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (—COO—), an amide bond (—NHCO—), or a urethane bond (—NHCOO—), or a divalent linking group derivable by combining one or more selected from these groups and bonds with —O— or —S—, or a single bond, Z Ａ represents a structure represented by the following formula (2A), a cyano group, or a phenyl group, R ２１ and R ２２ each independently represents a hydrogen atom or a methyl group,

9. 【Chemical Formula 4】 (In formula (2A), Z Ａ１ represents an alkyl group having 1 to 4 carbon atoms.) ​ The electrophotographic apparatus according to claim 8, wherein the polymer A has, as structural units, only the structural unit represented by the formula (1) and the structural unit represented by the formula (M).

10. The electrophotographic apparatus according to claim 8, wherein the ratio of the structural unit represented by the formula (1) to the structural unit represented by the formula (M) in the polymer A (formula (1): formula (M)) is 1:19 to 1:1 in terms of molar ratio.

11. The electrophotographic apparatus according to claim 1, wherein the content of the polytetrafluoroethylene particles in the surface layer of the electrophotographic photoreceptor is 5% by mass or more and 40% by mass or less based on the total mass of the surface layer of the electrophotographic photoreceptor.

12. The electrophotographic apparatus according to claim 1, wherein the binder material contained in the surface layer of the electrophotographic photoreceptor is a cured product of a hole-transporting compound having a chain polymerizable functional group.

13. The electrophotographic apparatus according to claim 12, wherein the hole-transporting compound having a chain polymerizable functional group is a compound represented by the following formula (CT-1) or (CT-2). [Chemical Formula 5] (In the formula (CT-1), Ar １１ to Ar １３ each independently represents a substituted aryl group or an unsubstituted aryl group, and the substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by any of the following formulas (P-1) to (P-3). However, the compound represented by the formula (CT-1) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3).) ​ (In the above formula (CT-2), Ar ２１ to Ar ２４ each independently represents a substituted aryl group or an unsubstituted aryl group, Ar ２５ represents a substituted arylene group or an unsubstituted arylene group, and the substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3), and the substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3). However, the compound represented by the formula (CT-2) has at least one monovalent functional group represented by any one of the following formulas (P-1) to (P-3).) 【Chemical Formula 7】 (In the formula (P-1), Z １１ represents a single bond or an alkylene group having 1 to 6 carbon atoms, and X １１ represents a hydrogen atom or a methyl group.) [Chemical Formula 8] (In the formula (P-2), Z ２１ represents a single bond or an alkylene group having 1 to 6 carbon atoms.) 【Chemical Formula 9】 (In the formula (P-3), Z ３１ represents a single bond or an alkylene group having 1 to 6 carbon atoms.)

14. The electrophotographic apparatus according to claim 1, wherein the surface layer of the electrophotographic photoreceptor further contains a compound represented by the following formula (3). 【Chemical Formula 10】 (In formula (3), R ３１ represents an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms, and R ３２ represents a fluoroalkyl group having 1 to 6 carbon atoms.)

15. The electrophotographic apparatus according to claim 1, wherein the number average molecular weight of the polymer B is 11,000 or more and 15,000 or less, and the peak top molecular weight is 24,000 or more and 40,000 or less.

16. The electrophotographic apparatus according to claim 1, wherein the binder material contained in the intermediate transfer belt is an acrylic resin.

17. The electrophotographic apparatus according to claim 1, wherein the content of the perfluoropolyether in the surface layer of the intermediate transfer belt is 20% by mass or more and 40% by mass or less based on the total solid content of the surface layer.

18. The electrophotographic apparatus according to claim 1, wherein the content of the polymer B contained in the surface layer of the intermediate transfer belt is 5% by mass or more and 30% by mass or less based on the total solid content of the surface layer.

19. The electrophotographic apparatus according to claim 1, wherein the surface layer of the intermediate transfer belt has a matrix-domain structure having a matrix containing the binder material and a domain containing the perfluoropolyether in its thickness direction, and the average major axis of the domain is 1 nm or more and 60 nm or less.

20. The surface layer of the electrophotographic photoreceptor is A layer formed by forming a coating film of a coating liquid for a surface layer containing the polymer A, at least one selected from a binder material and a raw material of the binder material, and the polytetrafluoroethylene particles, and drying and / or curing the coating film. The surface layer of the intermediate transfer belt is A layer formed by forming a coating film of a coating liquid for a surface layer containing the polymer B, at least one selected from a binder material and a raw material of the binder material, and the perfluoropolyether, and drying and / or curing the coating film. The electrophotographic apparatus according to claim 1.

Images