Image forming apparatus and process cartridge

Abstract

An image forming apparatus includes an image carrier and an intermediate transfer member, in which S1 / (S1 + S2) is at least 0.70 and not more than 1.00 when an area of particles on a surface of the image carrier is expressed as S1 and an area other than the particles is expressed as S2, and in a particle size distribution of the particles, S1 / (S1 + S2) is at least 0.70 and not more than 1.00. When a peak top particle diameter having a larger particle diameter value between a first peak having a maximum frequency and a second peak having a second large frequency among peaks having peak top particle diameters of 20 nm or more is denoted as DA and an arithmetic average curvature of peak points in a surface roughness shape of the intermediate transfer member is denoted as Spc, 80 nm < = DA < = 2 * (1 / Spc) is satisfied.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and a process cartridge. Background Art

[0002] As an electrophotographic imaging apparatus (such as a copier or printer) for forming a color image on a transfer material, a method using an intermediate transfer system is known. The intermediate transfer system forms an image by primarily transferring toners of multiple colors from an electrophotographic photosensitive member to an intermediate transfer member, and then secondarily transferring the toner images from the intermediate transfer member to the transfer material. Furthermore, to efficiently transfer the toners, a speed difference (peripheral speed difference) between the electrophotographic photosensitive member and the intermediate transfer member may be provided, particularly in the primary transfer section.

[0003] In the above-mentioned intermediate transfer system, when the friction between the electrophotographic photosensitive member and the intermediate transfer member is high and the lubricity is poor, the peripheral speed of the electrophotographic photosensitive member or the intermediate transfer member becomes unstable, and image blurring occurs in the primary transfer section. As one means of reducing friction, a method has been proposed in which a convex shape is formed by including particles on the surface of the electrophotographic photosensitive member.

[0004] Patent Document 1 describes a technique for reducing friction using an electrophotographic photosensitive member whose surface layer is obtained by curing a coating film containing organic resin particles (at least one of acrylic resin particles and melamine resin particles) and a hole transporting compound having a polymerizable functional group.

[0005] Patent Document 2 describes a technique of including an inorganic filler in the outermost layer of an electrophotographic photosensitive member to form a convex shape.

[0006] In image forming apparatuses using an electrophotographic system, photosensitive drums containing an organic photoconductive substance serving as a charge generating material are widely used as toner image carriers. In recent years, in order to extend the life of the photosensitive drum and improve image quality during repeated use, there has been a demand for improving the mechanical durability (i.e., wear resistance) of the photosensitive drum and maintaining surface properties.

[0007] As a method for transferring a toner image on a photosensitive drum to a recording material, imaging devices using an intermediate transfer system exist. In imaging devices using an intermediate transfer system, the toner image formed on the photosensitive drum is primarily transferred to an intermediate transfer member, and then the toner image on the intermediate transfer member is secondary transferred to the recording material. An endless intermediate transfer belt is widely used as the intermediate transfer member. In the primary transfer process, a high-voltage power supply is typically used to create a potential difference between the photosensitive drum surface and the intermediate transfer belt, thereby transferring the toner image on the photosensitive drum to the intermediate transfer belt via electrostatic force. Recently, there has been a growing demand for imaging devices to reduce the size of the device and process cartridges and increase the number of printable sheets, leading to an increasing demand for technologies that efficiently and effectively transfer toner without waste. As a method for improving transfer efficiency, a configuration has been proposed in which a convex shape is applied to the surface of the photosensitive drum to reduce the contact area with the toner, thereby reducing adhesion.

[0008] Means for imparting convexity to the surface of a photosensitive drum have been proposed in the past, and Patent Document 3 proposes a structure in which convexity having a height of 20 nm or more is formed on the surface of a photosensitive drum made of a curable resin by adding filler to prevent external additives from forming a film on the surface of the photosensitive drum.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2019-045862

[0012] Patent Document 2: Japanese Patent Application Publication No. 2020-071423

[0013] Patent Document 3: Japanese Patent 6361958 Summary of the Invention

[0014] Technical problem to be solved by the invention

[0015] In recent years, there has been a growing demand for extending the lifespan of imaging devices. However, with conventional technologies, as the lifespan increases, maintaining a convex shape in the latter half of the electrophotographic photosensitive member's lifespan becomes difficult due to wear or shedding of particles added to the surface of the electrophotographic photosensitive member. As a result, the friction-reducing effect is not achieved in the latter half of the lifespan, and image blurring occurs.

[0016] An object of the present invention is to suppress the occurrence of image defects by suppressing an increase in frictional force between an electrophotographic photosensitive member and an intermediate transfer member of an image forming apparatus.

[0017] When a convex shape is formed by adding filler, depending on the amount of filler particles added, their particle size, and their exposure, the adhesion to the toner may not be reduced, and the transfer efficiency may not be improved. Furthermore, the added filler may be detached due to friction with the intermediate transfer belt, and high transfer efficiency may not be maintained throughout the product life.

[0018] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to achieve both improvement of transfer efficiency and suppression of changes in the surface shape of a photosensitive drum during long-term use.

[0019] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

[0020] Solutions to the Problem

[0021] The present invention adopts the following structure.

[0022] An imaging device comprising:

[0023] an image bearing body; and

[0024] an intermediate transfer member configured to transfer the toner on the image carrier to a surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material;

[0025] in:

[0026] The image carrier has a surface layer containing particles and a binder resin,

[0027] On the surface of the surface layer, when the area occupied by the particles is represented by S1 and the area occupied excluding the particles is represented by S2, S1 / (S1+S2) is at least 0.70 and not more than 1.00,

[0028] There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer.

[0029] Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and

[0030] When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA,

[0031] When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc,

[0032] Satisfies 80nm≤DA≤2×(1-Spc).

[0033] The present invention also adopts the following structure. That is,

[0034] An imaging device comprising:

[0035] an image carrier; and

[0036] an intermediate transfer member configured to transfer the toner on the image carrier to a surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material,

[0037] in:

[0038] The image carrier has a surface layer containing particles and a binder resin,

[0039] There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer.

[0040] wherein, among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and

[0041] When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA,

[0042] When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and

[0043] The standard deviation of the distance between the centers of gravity of the convex parts is 250nm or less, and

[0044] When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc,

[0045] Satisfies 8 0 nm≤ DA ≤ 2X (1 / Spc).

[0046] The present invention also adopts the following structure. That is,

[0047] A process cartridge attachable to an image forming apparatus having an intermediate transfer member, the process cartridge comprising:

[0048] an image carrier having a surface layer containing particles and a binder resin;

[0049] wherein, on the surface of the surface layer, when the area occupied by the particles is represented by S1 and the area occupied excluding the particles is represented by S2, S1 / (S1+S2) is at least 0.70 and not more than 1.00,

[0050] There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer.

[0051] Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and

[0052] When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA,

[0053] Satisfy 80nm≤DA,

[0054] The intermediate transfer member of the image forming apparatus is an intermediate transfer member configured to transfer the toner on the image carrier to the surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material;

[0055] When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc,

[0056] Satisfies DA≤2×(1 / Spc).

[0057] The present invention also adopts the following structure. That is,

[0058] A process cartridge attachable to an image forming apparatus having an intermediate transfer member, the process cartridge comprising:

[0059] an image carrier having a surface layer containing particles and a binder resin,

[0060] There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer.

[0061] Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and

[0062] When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA,

[0063] Satisfy 80nm≤DA,

[0064] When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and

[0065] The standard deviation of the distance between the centers of gravity of the convex parts is 250nm or less, and

[0066] The intermediate transfer member of the image forming apparatus is an intermediate transfer member configured to transfer the toner on the image carrier to the surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to the transfer material, and

[0067] When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc,

[0068] Satisfies DA≤2×(1 / Spc).

[0069] The present invention adopts the following structure.

[0070] An image forming apparatus comprising: an endless transfer belt stretched by a plurality of stretching rollers; and a transfer member provided on an inner peripheral side of the transfer belt, wherein a process cartridge is attachable to the image forming apparatus,

[0071] wherein the width of the transfer member in the axial direction of the plurality of tenter rollers is smaller than the width of at least one of the plurality of tenter rollers;

[0072] The process cartridge has an image bearing member having a surface layer on which a toner image is carried.

[0073] The image carrier contains particles partially exposed from a surface layer of the image carrier,

[0074] The volume average particle size of the particles is greater than 37 nm and less than 550 nm,

[0075] 80% by number or more of the particles contained in the cross section of the surface layer are partially exposed from the surface layer, and the total volume of the exposed portion is at least 30% by volume and not more than 80% by volume relative to the total volume of the contained particles, and

[0076] In the axial direction, the width of the surface layer of the image carrier is formed in a region wider than the width of the transfer member.

[0077] The present invention also adopts the following structure. That is,

[0078] A process cartridge attachable to an image forming apparatus having an endless transfer belt stretched by a plurality of stretching rollers and a transfer member provided on the inner peripheral side of the transfer belt, wherein, in the image forming apparatus, the width of the transfer member in the axial direction of the plurality of stretching rollers is smaller than the width of at least one of the plurality of stretching rollers,

[0079] The process cartridge includes an image carrier having a surface layer that carries a toner image.

[0080] wherein the image carrier has particles partially exposed from a surface layer,

[0081] The volume average particle size of the particles is greater than 37 nm and less than 550 nm.

[0082] 80% by number or more of the particles contained in the cross section of the surface layer are partially exposed from the surface layer, and the total volume of the exposed portion is at least 30% by volume and not more than 80% by volume relative to the total volume of the contained particles, and

[0083] In the axial direction, the width of the surface layer of the image carrier is formed in a region wider than the width of the transfer member.

[0084] Advantageous Effects of the Invention

[0085] According to the present invention, the occurrence of image defects can be suppressed by suppressing an increase in frictional force between an electrophotographic photosensitive member and an intermediate transfer member of an image forming apparatus.

[0086] According to the present invention, it is possible to achieve both improvement in transfer efficiency and suppression of changes in the surface shape of the photosensitive member during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 is a schematic cross-sectional view of an imaging apparatus.

[0088] Figure 2 is an example of the layer configuration of the electrophotographic photosensitive member.

[0089] Figure 3 is another example of the layer configuration of the electrophotographic photosensitive member.

[0090] Figure 4 is a sectional view of the intermediate transfer member.

[0091] Figure 5 (A) and Figure 5 (B) is a schematic diagram in the case where the intermediate transfer member is subjected to surface treatment.

[0092] Figure 6 (A) and Figure 6 (B) is a schematic cross-sectional view illustrating the relationship between the electrophotographic photosensitive member and the intermediate transfer member.

[0093] Figure 7 is a schematic diagram of the surface of the electrophotographic photosensitive member viewed from above.

[0094] Figure 8 (A) and Figure 8 (B) is a graph showing the particle size distribution of particles in the surface layer.

[0095] Figure 9 is a schematic cross-sectional view showing a schematic configuration of the imaging apparatus.

[0096] Figure 10 (A) Figure 10 (B) and Figure 10 (C) is a conceptual diagram of a layer structure in a cross section of a photosensitive drum.

[0097] Figure 11 is a conceptual diagram illustrating the exposed volume of particles in the surface layer of a photosensitive drum.

[0098] Figure 12 (A-1), Figure 12 (A-2) and Figure 12 (A-3) is a diagram illustrating a deformed state at an end portion of the tension roller of the first image forming apparatus.

[0099] Figure 13 (B-1), Figure 13 (B-2) and Figure 13 (B-3) is a diagram illustrating a deformed state at an end portion of the tension roller of the second image forming apparatus.

[0100] Figure 14 (C-1), Figure 14 (C-2) and Figure 14 (C-3) is a diagram illustrating a deformed state at an end portion of the tension roller of the third image forming apparatus. DETAILED DESCRIPTION

[0101] Preferred examples of the present invention will be described in detail below with reference to the accompanying drawings. However, the size, material, shape, relative arrangement, etc. of the components described in the following examples should be appropriately changed according to the configuration and various conditions of the equipment to which the present invention is applied. Therefore, unless otherwise specified, the scope of the present invention is not limited. Although multiple features are described in the examples, not all of these multiple features are essential to the present invention, and these multiple features can be arbitrarily combined.

[0102] <Description of Imaging Apparatus>

[0103] Figure 1is a schematic sectional view of a color imaging device 100 according to this example. The imaging unit 30 forms overlapping toner images of multiple colors, here four colors of yellow (Y), magenta (M), cyan (C) and black (K), on a moving intermediate transfer member 8. Therefore, the imaging unit 30 includes four process cartridges P (PY, PM, PC and PK) as developing devices that can be attached to the main body of the imaging device 100. In addition, the imaging unit 30 includes an intermediate transfer unit 40 using the intermediate transfer member 8. The four process cartridges PY, PM, PC and PK have the same structure. The difference is that the image is formed by the toner of the color (i.e., yellow (Y), magenta (M), cyan (C) and black (K)) contained in the process cartridge P. Note that the letters Y, M, C and K at the end of the figure marks represent the toner colors and will be omitted when describing matters common to each color below.

[0104] The process cartridge P includes a toner container 23, an electrophotographic photosensitive member 1 serving as an image carrier, a charging roller 2, and a developing roller 3. A laser unit 7 is positioned below the process cartridge P and exposes the electrophotographic photosensitive member 1 based on an image signal. The electrophotographic photosensitive member 1 is driven to rotate clockwise at a predetermined circumferential speed as indicated by the arrow. Subsequently, the electrophotographic photosensitive member 1 is charged to a predetermined negative potential by applying a predetermined negative voltage to the charging roller 2, and then an electrostatic latent image is formed by scanning exposure using the laser unit 7. The electrostatic latent image is reverse-developed by applying a predetermined negative voltage to the developing roller 3, forming a toner image (negative polarity) on the electrophotographic photosensitive member 1. This process is referred to as a development process.

[0105] The intermediate transfer unit 40 includes an intermediate transfer member 8, which is a flexible endless belt-like body, a drive roller 9 that suspends and stretches the intermediate transfer member 8, and a driven roller 10. Furthermore, primary transfer rollers 6 are provided on the inner side of the intermediate transfer member 8 so as to face the electrophotographic photosensitive members 1 and are in contact with the corresponding electrophotographic photosensitive members 1 via the intermediate transfer member 8. The contact portion between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 is a primary transfer nip. A transfer voltage is applied to the primary transfer rollers 6 by a voltage applying device (not shown).

[0106] The intermediate transfer member 8 is driven by the rotation of the drive roller 9, rotating (moving) at a constant circumferential speed in the counterclockwise direction indicated by arrow A. By applying a positive voltage to the primary transfer roller 6, the negative toner image formed on the electrophotographic photosensitive member 1 is primarily transferred to the intermediate transfer member 8 at the primary transfer nip. Four color toner images of Y, M, C, and K are formed on the intermediate transfer member 8 in this order, overlapping each other. This process is referred to as the primary transfer process. Subsequently, the intermediate transfer member 8 rotates (moves) and is conveyed to the secondary transfer nip, which is the contact area between the intermediate transfer member 8 and the secondary transfer roller 11.

[0107] The feeding and conveying device 12 includes a feed roller 14 that feeds the transfer material S from a transfer material cassette 13 loaded and stored with sheet-like transfer material S, and a conveying roller pair 15 that conveys the fed transfer material S. The transfer material S conveyed from the feeding and conveying device 12 is introduced into the secondary transfer nip by a registration roller pair 16 at predetermined control timing, where it is gripped and conveyed. A positive voltage is applied to the secondary transfer roller 11. As a result, the four-color superimposed toner images on the intermediate transfer member 8 side are secondary-transferred onto the transfer material S, either sequentially or collectively, relative to the transfer material S gripped and conveyed at the secondary transfer nip. This process is referred to as the secondary transfer process.

[0108] The transfer material S on which the toner image has been formed by the secondary transfer as described above is introduced into the fixing device 17 as a fixing unit. The transfer material S on which the toner image has been heated and fixed by the fixing device 17 is discharged onto the discharge tray 50 by the discharge roller pair 20.

[0109] In the process cartridge P, the toner remaining on the surface of the electrophotographic photosensitive member after the primary transfer of the toner image from the electrophotographic photosensitive member 1 to the intermediate transfer member 8 (primary transfer residual toner) is charged to negative polarity, which is the normal charging polarity, when passing through the charging roller 2. Thereafter, the primary transfer residual toner is recovered by the developing roller 3 and reused based on the potential difference between the electrophotographic photosensitive member 1 and the developing roller 3. That is, in this example, a so-called drum-less cleaner system is used, without a primary transfer residual toner cleaning device.

[0110] Toner remaining on the surface of the intermediate transfer member 8 after the secondary transfer of the toner image from the intermediate transfer member 8 to the transfer material S is removed by a cleaning blade 21 in contact with the intermediate transfer member 8. The removed toner is recovered in a waste toner recovery container 22.

[0111] The electrophotographic photosensitive member 1 is driven to rotate by a driving device (not shown), and the intermediate transfer member 8 is rotated by the rotational drive of the driving roller 9. Therefore, if a rotational speed difference is provided between the driving device and the driving roller 9, a peripheral speed difference can be provided between the peripheral speeds of the electrophotographic photosensitive member 1 and the intermediate transfer member 8. It is known that when there is a peripheral speed difference between the peripheral speeds of the electrophotographic photosensitive member 1 and the intermediate transfer member 8, the primary transferability is improved by the effect of rolling the toner at the primary transfer nip.

[0112] <Description of image blur>

[0113] When the friction between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 is high, the peripheral speed of the electrophotographic photosensitive member 1 tends to fluctuate. While the friction is high when the electrophotographic photosensitive member 1 and the intermediate transfer member 8 are in direct contact, when toner enters the primary transfer nip, the friction decreases due to the toner intervening between the electrophotographic photosensitive member 1 and the intermediate transfer member 8, causing the peripheral speed of the electrophotographic photosensitive member 1 to fluctuate momentarily. This distorts the electrostatic latent image formed by exposure with the laser unit 7, causing image blur (exposure blur). Furthermore, toner in the primary transfer section may shift, causing image blur (primary transfer blur). As a countermeasure, maintaining constant frictional resistance both when toner is present in the primary transfer nip and when toner is absent from the primary transfer nip—that is, reducing friction when the primary transfer nip is empty (when the electrophotographic photosensitive member 1 and the intermediate transfer member 8 are in direct contact with each other)—is an effective countermeasure.

[0114] Therefore, by using the electrophotographic photosensitive member 1 and the intermediate transfer member 8 described below, even when the electrophotographic photosensitive member 1 and the intermediate transfer member 8 are in contact with each other, it is possible to reduce frictional force and suppress image blurring.

[0115] <Description of Electrophotographic Photosensitive Member>

[0116] The electrophotographic photosensitive member 1 of the present invention includes a surface layer which will be described later. Figure 2 and Figure 3 An example of the layer configuration of the electrophotographic photosensitive member is shown. Figure 2 and Figure 3 , reference numeral 101 denotes a support, reference numeral 102 denotes an undercoat layer, reference numeral 103 denotes a charge generating layer, and reference numeral 104 denotes a charge transporting layer. Reference numeral 105 denotes a surface layer according to the present invention, and reference numerals 106 and 107 denote particles contained in the surface layer 105. The particle size of the particles (first particles) represented by reference numeral 106 is larger than the particle size of the particles (second particles) represented by reference numeral 107. Reference numeral 108 denotes a binder resin.

[0117] Examples of methods for producing the electrophotographic photosensitive member of the present invention include a method of preparing a coating solution for each layer to be described later, applying the coating solution in the order of the desired layers, and drying the coating solution. In this case, examples of the method for applying the coating solution include dip coating, spray coating, inkjet coating, roller coating, die coating, blade coating, curtain coating, wire coating, ring coating, and dispenser coating. Among them, dip coating is preferred from the viewpoint of efficiency and productivity.

[0118] Each layer will be described below.

[0119] <Surface layer>

[0120] The electrophotographic photosensitive member 1 of the present invention is an electrophotographic photosensitive member 1 having a surface layer 105, the surface layer containing particles 106 and 107 and a binder resin 108, and having multiple peaks in the particle size distribution based on the number of particles. Among the multiple peaks, the peak with a peak top of 20 nm or more and the maximum peak top frequency is defined as the first peak. In addition, the peak with the second peak top frequency is defined as the second peak. The first peak and the second peak are compared, and the peak with the larger peak top particle size value is defined as peak PEA. In the present invention, the particle diameter DA of the peak top of peak PEA needs to be 80 nm or more and needs to be within a range determined based on the relationship with the arithmetic mean curvature Spc of the peak point obtained by measuring the surface roughness of the intermediate transfer member 8. The details of the relationship with the intermediate transfer member 8 will be described later.

[0121] Figure 8 (A) shows an example of a particle size distribution based on the number of particles, where the first peak appears at a particle size of 50 nm and the second peak appears at a particle size of 170 nm. In this case, the second peak with the larger particle size is peak PEA, and the particle size DA is 170 nm. Therefore, the condition of 80 nm ≤ DA is satisfied. In addition, since the particle size of the first peak is 50 nm, the condition of a particle size of 20 nm or greater at the peak top is satisfied.

[0122] Figure 8 (B) shows another example of particle size distribution. There is a peak at a particle size of 5 nm, but since the particle size at the peak top is less than 20 nm, this peak is not included in the first peak and the second peak. Figure 8 As in the case of (A), the peak with a particle size of 50 nm is the first peak, and the peak with a particle size of 170 nm is the second peak. The reason for selecting the peaks in this way will be described. Here, even in the electrophotographic photosensitive member 1 containing a large number of very small particles in the surface layer 105, the effects of the present invention as described later can be obtained. Therefore, as Figure 8 As described in , by selecting the first peak and the second peak from peaks having a particle diameter of 20 nm or more, the effects of the present invention can be stably obtained.

[0123] In such a configuration of the surface layer 105, the particle diameter DA at the peak top of the peak PEA represents the particle diameter of the particle with the highest particle diameter frequency or the second highest frequency in the surface layer, excluding particles smaller than 20 nm. According to the present inventors' research, when the particle diameter DA is 80 nm or greater, an effect of reducing the frictional force between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 is achieved. When the particle diameter DA is less than 80 nm, the convex portions generated by the smaller particles contained in the surface layers of the intermediate transfer member 8 and the electrophotographic photosensitive member 1 contribute to the contact between the electrophotographic photosensitive member 1 and the intermediate transfer member 8, and the number of contact points increases, thereby increasing the frictional force.

[0124] Next, on the surface of the surface layer of the electrophotographic photosensitive member 1 of the present invention, when the area occupied by particles is represented by S1 and the area occupied excluding particles is represented by S2, it is preferred that S1 / (S1+S2) is at least 0.70 and not more than 1.00.

[0125] On the other hand, when S1 / (S1+S2) is less than 0.70, the particle-free portions cannot form projections, increasing the contact area between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 and minimizing friction. Furthermore, due to the high particle ratio and increased density, particles are prevented from detaching when impacted tangentially to the surface of the electrophotographic photosensitive member. This is because the binder resin not only constrains the particles but also prevents their movement from being affected by other particles. Theoretically, the upper limit of S1 / (S1+S2) is 1.00. More preferably, S1 / (S1+S2) is at least 0.80 and no greater than 1.00, and even more preferably, S1 / (S1+S2) is at least 0.85 and no greater than 0.95.

[0126] In addition, when particles having a particle diameter within the range of DA ± 20 nm are referred to as particles PAA, protrusions derived from the particles PAA are referred to as CA, and when the surface layer of the electrophotographic photosensitive member 1 is observed from above, it is preferred that the average value of the distance between the centers of gravity of the protrusions CA is at least 150 nm and not more than 500 nm, and the standard deviation of the distance between the centers of gravity is 250 nm or less.

[0127] When the number of projections CA generated by particles in the surface layer 105 is small, the distance between the centers of gravity of the projections CA is large, the contact area between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 increases, and the frictional force cannot be reduced. When the distance between the centers of gravity of the projections CA in the surface layer is too small, the surface layer is filled with the projections CA, and as a result, the number of contact points between the surface layer 105 and the intermediate transfer member 8 increases. The distance between the centers of gravity in the present invention is more preferably at least 150 nm and not more than 450 nm, and further preferably at least 150 nm and not more than 400 nm.

[0128] On the other hand, when the standard deviation of the distance between the centers of gravity of the projections CA exceeds 250 nm, the distribution of the projections CA in the surface layer 105 changes, the friction between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 becomes uneven, and the peripheral speed of the electrophotographic photosensitive member 1 or the intermediate transfer member 8 becomes uneven. When the peripheral speed becomes uneven, image blurring is likely to occur. In addition, as long as the distance between the centers of gravity falls within the range of the average value and the standard deviation, the particles are densely present and the durability of the particles against detachment is high.

[0129] In order to improve the durability of the electrophotographic photosensitive member 1 and maintain the friction-reducing effect even in the latter half of the life of the image forming apparatus 100, either "S1 / (S1+S2) is at least 0.70 and not more than 1.00" or "the average value of the distance between the centers of gravity of the convex portions CA is at least 150 nm and not more than 500 nm, and the standard deviation of the distance between the centers of gravity is 250 nm or less" is a necessary condition. More preferably, S1 / (S1+S2) is at least 0.70 and not more than 1.00, the average value of the distance between the centers of gravity of the convex portions CA is at least 150 nm and not more than 500 nm, and the standard deviation of the distance between the centers of gravity is 250 nm or less.

[0130] In the cross section of the surface layer 105 of the electrophotographic photosensitive member 1 of the present invention, when the average film thickness of the surface layer at the portion not containing the particles PAA is T, it is preferable to satisfy DA>T. When DA is equal to or less than the average film thickness T, it becomes difficult to form convex portions, and thus it is likely that the effect of reducing the frictional force between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 cannot be obtained. In the case of Figure 2 and Figure 3 In the state where the particles are stacked, the average film thickness T is preferably 50 nm to 500 nm to satisfy the above formula, more preferably 70 nm to 450 nm, and even more preferably 80 nm to 400 nm.

[0131] In addition, when comparing the first peak and the second peak and defining the peak with the smaller peak top particle size value as the peak PEB, preferably, the particle size DB of the peak top of the peak PEB satisfies DB < T. When defining the particles having a particle size within the range of DB ± 20 nm among all the particles included in the surface layer 105 as the particles PAB, by making DB equal to or less than the average film thickness T, the compactness of the particles PAA forming the convex portions CA and the particles PAB arranged between the convex portions CA is enhanced, and the detachment of the particles is suppressed. When DB is equal to or greater than the average film thickness T, the particles PAB are likely to be exposed on the surface, and the detachment of the particles easily progresses.

[0132] In addition, preferably, DA and DB satisfy DB / DA > 1 / 10. The detachment of the particles in the tangential direction with respect to the surface layer of the electrophotographic photosensitive member 1 can be suppressed while sufficiently maintaining the height of the convex portions CA.

[0133] Next, preferably, the proportion of the number of the convex portions CA in the number of the convex portions present on the surface of the surface layer 105 of the electrophotographic photosensitive member 1 of the present invention is 90% or more in terms of number. The convex portions other than the convex portions CA do not originate from the particles PAA and refer to the portions having a height greater than the average film thickness T. The convex portions other than the convex portions CA are generated by the particles PAB smaller than the particles PAA or the film thickness non-uniformity of the binder resin. Such convex portions have low mechanical strength, and the convex portions are liable to wear due to sliding in the tangential direction of the electrophotographic photosensitive member. When the proportion of the number of the convex portions CA is less than 90% in terms of number, the number of the worn convex portions increases, and it becomes difficult to maintain a good frictional force state for a long time.

[0134] The half-value width of the peak PEA is preferably 50 nm or less. Since the height of the convex portions CA is controlled by the size of the particle size, the half-value width of the peak PEA is preferably within a constant range as much as possible. When the half-value width of the peak PEA exceeds 50 nm, the change in the height of the convex portions CA also increases, and the contact state between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 is liable to change.

[0135] The roundness of the particles PAA is preferably 0.950 or more. When the roundness of the particles PAA is less than 0.950, the contact area between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 increases. The average roundness of the particles is obtained as follows using a scanning electron microscope. The particles to be measured are observed using a scanning electron microscope (“JSM7800F”, manufactured by JEOL Ltd.), and the particle size of each of 100 particles is measured from the image obtained by the observation. For each particle, the longest side a and the shortest side b of the particle are measured once, and the roundness is defined as b / a. The roundness of 100 particles is averaged to calculate the average roundness.

[0136] The surface layer 105 of the electrophotographic photosensitive member 1 of the present invention contains at least the above-mentioned particles PAA and particles PAB. Examples of the particles PAA used in the present invention include organic resin particles (e.g., acrylic resin particles), inorganic particles (e.g., silica), and organic-inorganic hybrid particles. The particles PAA and the particles PAB may be the same material or different materials.

[0137] Acrylic particles contain polymers of acrylate or methacrylate. Among them, styrene acrylic particles are more preferred. There are no particular restrictions on the degree of polymerization of acrylic resins and styrene acrylic resins, or whether the resins are thermoplastic or thermosetting. Examples of organic resin particles include cross-linked polystyrene, cross-linked acrylic resins, phenolic resins, melamine resins, polyethylene, polypropylene, acrylic particles, polytetrafluoroethylene particles, and silicone particles.

[0138] Examples of inorganic particles include silica particles, metal oxide particles, and metal particles. Among these, silica particles are preferred. Since silica particles have a lower elastic modulus and a greater average circularity than other insulating particles, they are expected to promote point contact between the intermediate transfer member 8 and the photosensitive member 1, thereby reducing adhesion.

[0139] Known silica fine particles can be used as the silica particles, and either dry silica fine particles or wet silica fine particles can be used. Wet silica fine particles obtained by a sol-gel method (hereinafter also referred to as sol-gel silica) are preferred.

[0140] The sol-gel silica of the particles contained in the surface layer 105 of the electrophotographic photosensitive member 1 used in the present invention may be hydrophilic or may have a hydrophobized surface.

[0141] Examples of hydrophobic treatment methods include a sol-gel method in which the solvent is removed from a silica sol suspension, the silica sol suspension is dried, and then the silica sol suspension is treated with a hydrophobic agent, and a method in which a hydrophobic agent is directly added to the silica sol suspension and the silica sol suspension is treated simultaneously with drying. The method of directly adding a hydrophobic agent to the silica sol suspension is preferred from the viewpoints of controlling the half-value width of the particle size distribution and controlling the saturated water adsorption amount.

[0142] Examples of the hydrophobizing agent include the following.

[0143] Chlorosilanes, such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tert-butyldimethylchlorosilane, and vinyltrichlorosilane;

[0144] Alkoxysilanes, such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane , isobutyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-(2-aminoethyl)aminopropylmethyldimethoxysilane;

[0145] Silazanes, such as hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyltetramethyldisilazane, and dimethyltetravinyldisilazane;

[0146] Silicone oils such as dimethyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, methanol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, and terminally reactive silicone oil;

[0147] Siloxanes, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, and octamethyltrisiloxane;

[0148] Fatty acids and their metal salts include undecanoic acid, lauric acid, tridecanoic acid, dodecanoic acid, myristic acid, palmitic acid, pentadecanoic acid, stearic acid, heptadecanoic acid, long-chain fatty acids (such as arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc.), and salts of fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

[0149] Among them, alkoxysilane, silazane and silicone oil are preferably used because they are easy to be hydrophobized. These hydrophobizing agents can be used alone or in combination of two or more.

[0150] The surface layer 105 of the present invention may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slip agents, and wear resistance enhancers. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, silicone modified resins, silicone oils, and the like.

[0151] The surface layer 105 of the present invention can be formed by preparing a surface layer coating solution comprising the above-mentioned materials and a solvent, forming a coating film, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, sulfoxide solvents, ester solvents, and aromatic hydrocarbon solvents.

[0152] In surface layer 105 of the present invention, particle volume is preferably 40 volume % to 90 volume % relative to the ratio of surface layer 105 cumulative volumes.In addition, this ratio is more preferably 45 volume % to 85 volume %, and also more preferably 50 volume % to 80 volume %.Within this scope, can reliably realize the formation of the convex portion of surface layer as above.When this ratio was below 30 volume %, because the height of convex portion reduced, therefore can not reduce frictional force.When this ratio surpassed 90 volume % when more than, particle broke away from easily, and can not keep the effect that reduces frictional force when carrying out durability test.

[0153] In addition, in order to improve the charge transport capability of the surface layer 105, a charge transport material may be added to the surface layer coating liquid. In addition, additives may be added to improve various functions. Examples of additives include conductive particles, antioxidants, ultraviolet absorbers, plasticizers, and leveling agents.

[0154] Examples of the binder resin 108 according to the present invention include the following. Here, the surface layer 105 preferably contains a charge transporting material. Examples of the binder resin include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenolic resins, melamine resins, epoxy resins, and the like. Among these, polycarbonate resins, polyester resins, and acrylic resins are preferred.

[0155] The surface layer 105 of the present invention can be formed into a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. The example of the reaction at this time includes thermal polymerization, photopolymerization, radiation polymerization, etc. The example of the polymerizable functional group of the monomer having a polymerizable functional group includes an acrylic acid group, a methacrylic acid group, etc. As the monomer having a polymerizable functional group, a material with charge transporting ability can be used.

[0156] The compound having a polymerizable functional group may have both a chain-polymerizable functional group and a charge transport structure. From the perspective of charge transport, a triarylamine structure is preferred as the charge transport structure. The chain-polymerizable functional group is preferably an acryloyl group or a methacryloyl group. The number of functional groups may be one or more. Forming a cured film containing a compound having multiple functional groups and a compound having a single functional group is particularly preferred because strain generated by the polymerization of multiple functional groups can be easily eliminated.

[0157] Examples of the compound having one functional group are shown in (2-1) to (2-6).

[0158] <Chemical Formula 1>

[0159]

[0160] Examples of the above-mentioned compound having multiple functional groups are shown in (3-1) to (3-6).

[0161] <Chemical Formula 2>

[0162]

[0163] <Support>

[0164] In the present invention, the electrophotographic photosensitive member 1 preferably includes a support. In the present invention, the support is preferably a conductive support having conductivity. Examples of the shape of the support include cylindrical, belt-shaped, sheet-shaped, and the like. Among them, a cylindrical support is preferred. The surface of the support may be subjected to electrochemical treatment (e.g., anodization), sandblasting, cutting, and the like.

[0165] The material of the support is preferably metal, resin, glass, etc. Examples of metal include aluminum, iron, nickel, copper, gold, stainless steel, alloys thereof, etc. Among them, an aluminum support using aluminum is preferred.

[0166] Furthermore, conductivity can be imparted to resin or glass by a treatment such as mixing or coating with a conductive material.

[0167] <Conductive Layer>

[0168] In the present invention, a conductive layer may be provided on the support. Providing the conductive layer can shield scratches and irregularities on the support surface and control light reflection on the support surface. The conductive layer preferably contains conductive particles and a resin.

[0169] Examples of the material of the conductive particles include metal oxides, metals, carbon black, and the like.

[0170] Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, etc. Metals include aluminum, nickel, iron, nickel chromium, copper, zinc, silver, etc.

[0171] Among them, metal oxides are preferably used as the conductive particles, and titanium oxide, tin oxide, or zinc oxide is more preferably used.

[0172] When metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof.

[0173] Furthermore, the conductive particles may have a laminated structure in which uncoated particles (eg, titanium oxide, barium sulfate, zinc oxide) are coated with a metal oxide having a different composition from that of the uncoated particles. Examples of coatings include metal oxides (eg, tin oxide).

[0174] When a metal oxide is used as the conductive particles, the average primary particle size is preferably at least 1 nm and not more than 500 nm, more preferably at least 3 nm and not more than 400 nm.

[0175] 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.

[0176] The conductive layer may also contain a masking agent such as silicone oil, resin particles or titanium oxide.

[0177] The average film thickness of the conductive layer is preferably at least 1 μm and not more than 50 μm, particularly preferably at least 3 μm and not more than 40 μm.

[0178] The conductive layer can be formed by preparing a conductive layer coating solution containing the above-mentioned materials and a solvent, forming a coating film, and drying the coating film. Examples of solvents used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like. Examples of dispersion methods for dispersing the conductive particles in the conductive layer coating solution include methods using a paint shaker, a sand mill, a ball mill, or a liquid collision-type high-speed disperser.

[0179] <Base Coating>

[0180] In the present invention, a primer layer may be provided on the support or the conductive layer.

[0181] The average film thickness of the undercoat layer is preferably at least 0.1 μm and not more than 50 μm, more preferably at least 0.2 μm and not more than 40 μm, particularly preferably at least 0.3 μm and not more than 30 μm.

[0182] Examples of the resin of the undercoat layer include polyacrylic resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyethylene oxide resins, polypropylene oxide resins, ethyl cellulose resins, methyl cellulose resins, polyamide resins, polyamic acid resins, polyurethane resins, polyimide resins, polyamideimide resins, polyvinyl phenolic resins, melamine resins, phenolic resins, epoxy resins, and alkyd resins.

[0183] The resin may have a structure in which a resin having a polymerizable functional group and a monomer having a polymerizable functional group are cross-linked.

[0184] Furthermore, the undercoat layer may contain an inorganic compound or an organic compound in addition to the resin.

[0185] Examples of inorganic compounds include metals, oxides, and salts.

[0186] Examples of metals include gold, silver, and aluminum. Examples of oxides include zinc oxide, white lead, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, indium oxide, tin oxide, and zirconium oxide. Examples of salts include barium sulfate and strontium titanate.

[0187] These inorganic compounds may be present in the film in a particle state.

[0188] The number average particle diameter of the particles is preferably at least 1 nm and not more than 500 nm, more preferably at least 3 nm and not more than 400 nm.

[0189] These inorganic compounds may have a laminated structure including a core particle and a coating layer coating the core particle.

[0190] The surfaces of these inorganic compounds may be treated with silicone oil, silane compounds, silane coupling agents, other organic silicon compounds, organic titanium compounds, etc. In addition, elements such as tin, phosphorus, aluminum, niobium, etc. may be doped.

[0191] Examples of the organic compound include electron transport compounds and conductive polymers.

[0192] Examples of the conductive polymer include polythiophene, polyaniline, polyacetylene, polyphenylene, and polyethylenedioxythiophene.

[0193] Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silolene compounds, and boron-containing compounds.

[0194] The electron transport material has a polymerizable functional group and can be cross-linked with a resin having a functional group that can react with the functional group. Examples of the polymerizable functional group include hydroxyl, thiol, amino, carboxyl, vinyl, acryloyl, methacryloyl, and epoxy groups.

[0195] These organic compounds may be present in the film in a particle state, or the surface thereof may be treated.

[0196] Various additives such as leveling agents (eg, silicone oil), plasticizers, thickeners may be added to the basecoat.

[0197] The undercoat layer is obtained by preparing an undercoat layer coating solution containing the above-mentioned materials, then coating the coating solution on a support or a conductive layer, and then drying or curing the coating film.

[0198] Examples of the solvent used in preparing the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, and the like.

[0199] Examples of a dispersion method for dispersing the particles in the coating liquid include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0200] <Photosensitive Layer>

[0201] The photosensitive layer of the electrophotographic photosensitive member 1 is mainly divided into (1) a laminated photosensitive layer and (2) a single-layer photosensitive layer. (1) The laminated photosensitive layer is a photosensitive layer including a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material. (2) The single-layer photosensitive layer is a photosensitive layer containing both a charge generating material and a charge transporting material.

[0202] (1) Laminated photosensitive layer

[0203] The stacked photosensitive layer includes a charge generating layer and a charge transporting layer.

[0204] (1-1) Charge Generation Layer

[0205] The charge generating layer preferably contains a charge generating material and a resin.

[0206] Examples of charge generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments, etc. Among them, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.

[0207] The content of the charge generating material in the charge generating layer is preferably at least 40% by mass and not more than 85% by mass, more preferably at least 60% by mass and not more than 80% by mass, relative to the total mass of the charge generating layer.

[0208] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, etc. Among them, polyvinyl butyral resin is more preferred.

[0209] In addition, the charge generation layer may further contain additives such as an antioxidant, an ultraviolet absorber, etc. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, and the like.

[0210] The charge generation layer can be formed by preparing a charge generation layer coating solution containing the above-mentioned materials and a solvent, forming a coating film on the undercoat layer, and then drying the coating film. Examples of the solvent used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like.

[0211] The film thickness of the charge generating layer is preferably at least 0.1 μm and not more than 1.5 μm, more preferably at least 0.15 μm and not more than 1.0 μm.

[0212] (1-2) Charge transport layer

[0213] The charge transport layer preferably contains a charge transport material and a resin.

[0214] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, resins having groups derived from these materials, etc. Among them, triarylamine compounds and benzidine compounds are preferred.

[0215] The content of the charge transport material in the charge transport layer is preferably at least 25% by mass and not more than 70% by mass, more preferably at least 30% by mass and not more than 55% by mass, relative to the total mass of the charge transport layer.

[0216] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among them, polycarbonate resin and polyester resin are preferred. Polyester resin is particularly preferably polyarylate resin.

[0217] 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.

[0218] Furthermore, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slip-imparting agents, and wear resistance enhancers. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, silicone-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0219] The charge transport layer can be formed by preparing a charge transport layer coating solution containing the above-mentioned materials and a solvent, forming a coating film on the charge generating layer, and then drying the coating film. Examples of solvents used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Of these solvents, ether solvents or aromatic hydrocarbon solvents are preferred.

[0220] The film thickness of the charge transport layer is preferably at least 3 μm and not more than 50 μm, more preferably at least 5 μm and not more than 40 μm, particularly preferably at least 10 μm and not more than 30 μm.

[0221] (2) Single-layer photosensitive layer

[0222] A single-layer photosensitive layer can be formed by preparing a photosensitive layer coating solution containing a charge generating material, a charge transporting material, a resin, and a solvent, forming a coating film on the undercoat layer, and then drying the coating film. Examples of the charge generating material, the charge transporting material, and the resin are the same as those in the above-mentioned "(1) Laminated photosensitive layer".

[0223] The film thickness of the single-layer photosensitive layer is preferably at least 10 μm and not more than 45 μm, more preferably at least 25 μm and not more than 35 μm.

[0224] <Description of Intermediate Transfer Member>

[0225] Figure 4 : is a schematic cross-sectional view showing the configuration of the intermediate transfer member 8 in this example. The intermediate transfer member 8 includes a surface layer 8a and a base layer 8b. The surface layer 8a is provided on the outer peripheral surface side of the intermediate transfer member 8 relative to the base layer 8b, and has a surface that supports (holds) the toner transferred from the electrophotographic photosensitive member 1. The intermediate transfer member 8 preferably has an endless belt shape and preferably has a thickness of at least 10 μm and not more than 500 μm, particularly preferably at least 40 μm and not more than 100 μm.

[0226] Examples of materials constituting the base layer 8b include thermoplastic resins such as polycarbonate, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, poly(4-methylpentene)-1, polystyrene, polyamide, polysulfone, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polyethersulfone, polyethernitrile, thermoplastic polyimide, polyetheretherketone, thermotropic liquid crystal polymer, and polyamic acid. Two or more of these may be used in combination.

[0227] The intermediate transfer member 8 having an endless belt shape can be obtained by melt-kneading a conductive material or the like into such a thermoplastic resin and then molding the base layer 8b by appropriately selecting and using a molding method such as blow molding, cylindrical extrusion molding, or injection stretch blow molding.

[0228] The material constituting the surface layer 8a includes a curable resin 81 that is cured by heat or energy rays (such as light (ultraviolet rays, etc.) or electron beams) as a bonding material. As the curable resin 81, an acrylic resin obtained by curing an acrylic copolymer containing unsaturated double bonds is preferred. For example, an acrylic ultraviolet curable resin (trade name: Opster Z7501) manufactured by JSR Corporation can be used. The surface layer 8a contains an acrylic resin as the main component of the bonding material. Here, the main component means 50% by mass or more relative to the bonding material constituting the surface layer 8a.

[0229] A conductive material 82 for adjusting resistance is added to the surface layer 8a. As the conductive material 82, conductive fillers, resistance adjusters, etc. made of electronic conductive materials or ion conductive materials can be used. Examples of electronic conductive materials include granular, fibrous or flaky carbon-based conductive fillers, such as carbon black, PAN-based carbon fibers, and expanded graphite pulverized products. Examples of electronic conductive materials include granular, fibrous or flaky metal-based conductive fillers, such as silver, nickel, copper, zinc, aluminum, stainless steel, and iron. In addition, examples of electronic conductive materials include granular metal oxide-based conductive fillers, such as zinc antimonate, tin oxide doped with antimony, zinc oxide doped with antimony, indium oxide doped with tin, and zinc oxide doped with aluminum. Examples of ion conductive materials include ionic liquids, conductive oligomers, and resistance adjusters (such as quaternary ammonium salts). As the conductive material 82, one or more of the above materials can be appropriately selected and used, and electronic conductive materials and ion conductive materials can be mixed and used. Among them, from the perspective of small addition amount, granular (preferably submicron particles) metal oxide-based conductive fillers are preferably used as the conductive material 82.

[0230] In order to improve transfer efficiency and reduce friction relative to the cleaning blade 21 for the belt, surface layer particles 83 can be added to the surface layer 8a. The surface layer particles 83 are preferably solid lubricants and are generally insulating particles. Examples of the surface layer particles 83 include fluorine-containing particles, such as polytetrafluoroethylene (PTFE) resin powder, trifluorochloroethylene resin powder, tetrafluoroethylene hexafluoropropylene resin powder, vinyl fluoride resin powder, vinylidene fluoride resin powder, difluorodichloroethylene resin powder, graphite fluoride, and copolymers thereof. One or more surface layer particles 83 can be appropriately selected and used. In addition, the surface layer particles 83 can be solid lubricants, such as silicone resin particles, silicon dioxide particles, or molybdenum disulfide powder. Among them, polytetrafluoroethylene (PTFE) resin particles (such as emulsion polymerization PTFE resin particles) are preferred because the friction coefficient of the particle surface is low and the wear of other components (such as the cleaning blade 21 for the belt) that come into contact with the surface of the intermediate transfer member 8 can be reduced.

[0231] In order to satisfy the relationship between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 described later, it is preferable to uniformly form the surface layer 8a on the base layer 8b. As a specific method, a method of irradiating the entire surface area of the base layer 8b for a certain period of time by spraying, a method of applying an acrylic resin to the entire surface area of the base layer 8b of the cylindrical intermediate transfer member 8 from an annular nozzle, or the like can be used.

[0232] From the viewpoint of performing satisfactory image formation, the volume resistivity of the intermediate transfer member 8 is preferably at least 1×10 9 Ω·cm and not more than 1×10 12 The volume resistivity can be measured using a general-purpose measuring instrument Hiresta UPMCP-HT450 (manufactured by Mitsubishi Chemical Corporation) under an environment of a temperature of 25° C. and a humidity of 60% RH.

[0233] The surface layer 8a may be subjected to surface treatment. Figure 5 (A) is a schematic diagram of the surface of the intermediate transfer member 8 subjected to the surface treatment when viewed from above, and Figure 5 (B) is a schematic diagram of a cross section of the intermediate transfer member 8. The groove 84 is formed parallel to the arrow A indicating the rotation direction (movement direction) of the intermediate transfer member 8.

[0234] As a surface treatment, the grooves 84 can be formed by using embossing, in which a mold having a shape is brought into contact with the surface layer 8a of the rotating intermediate transfer member 8. By forming the grooves 84, the friction between the intermediate transfer member 8 and the cleaning blade 21 is reduced, and the cleaning blade 21 can be prevented from curling.

[0235] In this example, when surface treatment is performed, the grooves 84 have a groove width W of 1.5 μm, a groove depth D of 1.0 μm, and a groove interval I of 4.0 μm. However, the groove width W, groove depth D, and groove interval I are not limited thereto. The groove width W is preferably equal to or less than the average particle size of the toner so that the toner does not pass through the contact portion of the cleaning blade 21, and the groove depth D is preferably less than the thickness of the surface layer 8a and within a range such that the grooves do not disappear even if the surface layer 8a is scraped. The groove interval I is preferably appropriately set within a range that can suppress curling of the cleaning blade 21.

[0236] The surface treatment method is not limited to embossing, and a method of contacting a wrapping film with the intermediate transfer member 8 may be used as long as the grooves 84 can be formed so as to reduce friction between the intermediate transfer member 8 and the cleaning blade 21 and prevent curling.

[0237] <Relationship between Electrophotographic Photosensitive Member and Intermediate Transfer Member>

[0238] In the present invention, the arithmetic mean curvature Spc (ISO25178) of the peak points calculated from the surface roughness on the surface of the intermediate transfer member 8 facing the electrophotographic photosensitive member 1 needs to satisfy the relationship between the particle diameter DA in the surface layer 105 of the electrophotographic photosensitive member 1 and the following formula (1).

[0239] 80nm≤DA≤2×(1 / Spc)...(1)

[0240] The arithmetic mean curvature Spc of the peak point is the average of the principal curvatures of the peak point of the surface and is expressed as the inverse of the radius of curvature. Therefore, when Spc is small, it means that the peak point is round and has a wide convex shape, and when Spc is large, it means that the peak point has a narrow, sharp convex shape.

[0241] Figure 6 : is a schematic cross-sectional view showing the relationship between the surface of the intermediate transfer member 8 and the surface of the electrophotographic photosensitive member 1. "2×(1 / Spc)" described in formula (1) is a value equivalent to the particle size when the peak portion of the roughness on the surface of the intermediate transfer member 8 is regarded as a particle. The relationship of formula (1) is equivalent to the curvature radius of the particle size DA of the electrophotographic photosensitive member 1 being smaller than the curvature radius of the surface of the intermediate transfer member 8. Figure 6 As shown in (A), when formula (1) is satisfied, the intermediate transfer member 8 can be regarded as being substantially smooth with respect to the electrophotographic photosensitive member 1. Therefore, the friction of the intermediate transfer member 8 against the particles 106 in the surface layer 105 of the electrophotographic photosensitive member 1 can be reduced, and the frictional force can be reduced over a long period of time.

[0242] On the other hand, Figure 6 As shown in (B),

[0243] When DA>2×(1 / Spc),

[0244] It is difficult to maintain the shape of the surface layer 105 of the electrophotographic photosensitive member 1 throughout its life. Figure 6 As shown by the arrow in (B), when the peaks on the surface of the intermediate transfer member 8 apply stress to the particles 106 in the surface layer 105 of the electrophotographic photosensitive member 1 from the side of the particles 106, the particles 106 are easily detached. With use, the particles 106 are increasingly detached, the contact area between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 increases, and the frictional force increases. As described above, when the particle diameter DA is 80 nm or more, the effect of reducing the frictional force can be achieved.

[0245] For the reasons described above, in the present invention, in order to maintain the effect of reducing the friction between the electrophotographic photosensitive member 1 and the intermediate transfer member 8 even in the latter half of the life of the image forming apparatus 100 , it is necessary to satisfy the formula (1).

[0246] When Figure 5 When grooves are formed in the surface layer 8a along the moving direction of the intermediate transfer member 8, at least the arithmetic mean curvature Spc of the portion 85 without grooves needs to satisfy the formula (1). This is because the portion 85 without grooves of the surface layer 8a contacts the electrophotographic photosensitive member 1 and contributes to friction and durability.

[0247] [Example]

[0248] Hereinafter, measurement methods of various physical properties of the electrophotographic photosensitive member 1 and the intermediate transfer member 8 according to the present invention, manufacturing examples, and experimental examples will be described.

[0249] <Measurement of Physical Properties of Electrophotographic Photosensitive Member>

[0250] <Method of Observing the Lamination State of Particles Contained in the Surface Layer of the Electrophotographic Photosensitive Member and Measuring the Particle Size Distribution>

[0251] The cross section of the electrophotographic photosensitive member 1 prepared in Example was observed. It was determined whether the particles Figure 2 Are the particles stacked in a single layer in the surface layer as shown? Figure 3 The photosensitive member 1 was stacked in multiple layers as shown. Note that the sample for cross-sectional observation was obtained by dividing the photosensitive member 1 into four equal parts in the longitudinal direction and sampling at positions 1 / 4, 1 / 2, and 3 / 4 of the length from the end, offset 120° in the circumferential direction. 5 mm square sample pieces were cut from the photosensitive member, and the surface layer was three-dimensionalized to 2 μm × 2 μm × 2 μm using Slice & View of the FIB-SEM.

[0252] Slice&View conditions are as follows.

[0253] Analytical sample processing: FIB method

[0254] Processing and viewing device: NVision40 from SII / Zeiss

[0255] Slice interval: 10nm

[0256] (Observation conditions)

[0257] Accelerating voltage: 1.0 kV

[0258] Sample tilt: 54°

[0259] WD: 5mm

[0260] Detector: BSE detector

[0261] Aperture: 60μm, high current

[0262] ABC: Open

[0263] Image resolution: 1.25nm / pixel

[0264] The measurement environment is a temperature of 23°C and a pressure of 1×10 -4 Pa. As a processing and observation apparatus, Strata 400S manufactured by FEI (sample tilt: 52°) can also be used.

[0265] The analysis area was 2 μm long×2 μm wide, and the information of each cross section was integrated to obtain the information of each 2 μm long×2 μm wide×2 μm thick (8 μm thick) on the surface of the surface layer. 3 ) unit volume V. In addition, image analysis was performed on each cross section using image processing software Image-Pro Plus manufactured by MediaCybernetics.

[0266] The particle content in the total volume of the surface layer was calculated from the contrast difference of Slice & View of FIB-SEM. In addition, the particle content in the total volume of the surface layer was calculated based on the information obtained from image analysis in each of four sample slices in a volume of 2 μm × 2 μm × 2 μm (unit volume: 8 μm 3 ) in the present invention, and calculate the content of the conductive particles [volume %] (= V μm 3 / 8μm 3 ×100). The average value of the particle content in each sample piece was taken as the content of each particle of the present invention in the surface layer relative to the total volume of the surface layer [volume %]. The composition of the particles was determined using SEM-EDX function.

[0267] In a particle size distribution where the horizontal axis represents the particle size of particles contained on the surface of the surface layer and the vertical axis represents the number-based frequency of each particle size, the presence of multiple peaks is examined. In the particle size distribution, the particle size DA at the peak top of the aforementioned peak PEA is calculated. Similarly, the particle size DB at the peak top of the peak PEB is calculated.

[0268] When particles with different compositions are present, the particles are distinguished using EDS mapping images. In addition, 100 convex portions are measured, and the proportion of convex portions CA originating from particles PAA is calculated. Figure 2 and Figure 3 As shown, in the cross-sectional image of the surface layer, the average film thickness T of the surface layer was measured.

[0269] <Method of Measuring Average and Standard Deviation of Distances Between Centers of Gravity of Particles in Surface Layer of Electrophotographic Photosensitive Member>

[0270] In the electrophotographic photosensitive member 1 of the present invention, when the surface layer 105 is observed from above, the average value and standard deviation of the distances between the centers of gravity of the projections CA derived from the particles PAA can be calculated as follows.

[0271] The surface of the surface layer 105 of the electrophotographic photosensitive member 1 was photographed using a scanning electron microscope (SEM) ("S-4800" manufactured by JEOL Ltd.) at an accelerating voltage of 10 kV. A 30,000-magnification photographic image of the surface layer 105 of the electrophotographic photosensitive member 1 of the present invention was obtained by a scanner at a total of 12 locations (including three locations 50 mm from each end and in the longitudinal center, and four locations every 90 degrees in the circumferential direction). The particle PAA of the photographic image was binarized using an image processing analyzer ("LUZEXAP" manufactured by Nireco Corporation).

[0272] In the model of the distance between the centers of gravity of adjacent particles PAA, as Figure 7 As shown, the distance 201 between the centers of gravity of adjacent particles PAA is measured, and the average value of the distance between the centers of gravity is calculated. At this time, the distance between the centers of gravity is calculated by performing Voronoi segmentation based on the centers of gravity of the particles PAA. The distance between the centers of gravity and the standard deviation are calculated for a total of 10 fields of view, and the average value and standard deviation of the distance between the centers of gravity obtained are defined as the average value and standard deviation of the distance between the centers of gravity of the particles in the surface layer of the photosensitive member.

[0273] <Method of Measuring Particle Coverage Ratio S1 / (S1+S2) in Surface Layer of Electrophotographic Photosensitive Member>

[0274] In the electrophotographic photosensitive member 1 of the present invention, when the surface layer 105 is observed from above, the coverage S1 / (S1+S2) can be calculated as follows, where the area of the particles PAA is S1 and the total area excluding the particles PAA is S2.

[0275] The surface of the surface layer 105 of the electrophotographic photosensitive member 1 was photographed using a scanning electron microscope (SEM) ("S-4800" manufactured by JEOL Ltd.) at an accelerating voltage of 10 kV. A 30,000-magnification photographic image of the surface layer 105 of the electrophotographic photosensitive member 1 of the present invention was obtained by a scanner at a total of 12 locations (including three locations 50 mm from each end and in the longitudinal center, and four locations every 90 degrees in the circumferential direction). The particle PAA of the photographic image was binarized using an image processing analyzer ("LUZEXAP" manufactured by Nireco Corporation).

[0276] The coverage ratio S1 / (S1+S2) (%) was calculated with the area of the particles PAA being S1 and the total area excluding the particles PAA being S2. The above coverage ratio was calculated for a total of 10 fields, and the average value of the obtained coverage ratios was regarded as the coverage ratio of the particles in the surface layer 105 of the photosensitive member 1.

[0277] <Method for Measuring Circularity of Particles PAA in Surface Layer Particles of Electrophotographic Photosensitive Member>

[0278] The surface of the surface layer 105 of the electrophotographic photosensitive member 1 was photographed using a scanning electron microscope (SEM) ("S-4800", manufactured by JEOL Ltd.) at an accelerating voltage of 10 kV. A 30,000-magnification photographic image of the surface layer 105 of the electrophotographic photosensitive member 1 of the present invention was acquired by a scanner at a total of 12 locations (including three locations 50 mm from each end and the longitudinal center, and four locations every 90 degrees in the circumferential direction). Furthermore, the particles PAA of the photographic image were image-processed using an image processing analyzer ("LUZEX AP", manufactured by Nireco), and the average value of the circularity for a total of 10 fields of view was calculated to obtain the circularity of the particles PAA.

[0279] <Measurement of Film Thickness of Each Layer>

[0280] The film thickness of each layer of the electrophotographic photosensitive member 1 of Examples and Comparative Examples, except the charge generating layer, was obtained by a method using an eddy current film thickness meter (Fischerscope, manufactured by Fischer Instruments) or a method of converting the specific gravity from the mass per unit area. The film thickness of the charge generating layer was measured by converting the Macbeth density value of the photosensitive member using a calibration curve obtained in advance from the Macbeth density value measured by pressing a spectrodensitometer (trade name: X-Rite 504 / 508, manufactured by X-Rite) against the surface of the photosensitive member and the film thickness measurement value observed by cross-sectional SEM image.

[0281] <Measurement of Arithmetic Mean Curvature Spc of Peak Points of Intermediate Transfer Member Surface>

[0282] Specifically, the arithmetic mean curvature Spc of the peak points of the surface of the intermediate transfer member 8 can be measured as follows.

[0283] The surface of the intermediate transfer member 8 was measured using a laser microscope VK-X250 (manufactured by KEYENCE) in shape measurement mode at a magnification of 150. The intermediate transfer member of the present invention was measured at a total of 12 locations, including three locations in the center 50 mm from each end in the width direction (a direction perpendicular to the direction of rotation of the intermediate transfer member) and four locations equally spaced in the direction of rotation. The measurement range at each location was 70 μm × 70 μm.

[0284] From the measured microscopic image, the arithmetic mean curvature of the peak points was calculated in the surface roughness measurement mode using the analysis software (VK-H1XA) included with the laser microscope VK-X250. The average value of the values at all 12 positions was defined as the arithmetic mean curvature Spc of the peak points on the surface of the intermediate transfer member 8.

[0285] In the case where grooves are formed on the surface of the intermediate transfer member 8 , for each measurement position, only positions without grooves are analyzed, and the arithmetic mean curvature of the peak points is calculated.

[0286] <Manufacture of Electrophotographic Photosensitive Member>

[0287] The support, conductive layer, undercoat layer, charge generating layer, charge transporting layer and surface layer were prepared by the following method.

[0288] <Preparation of Conductive Layer Coating Liquid 1>

[0289] Anatase titanium oxide having an average primary particle size of 200 nm is used as a matrix, and a titanium niobium sulfuric acid solution containing 33.7 parts of titanium (in terms of TiO2) and 2.9 parts of niobium (in terms of Nb2O5) is prepared. 100 parts of the matrix are dispersed in pure water to form a suspension of 1000 parts, and the suspension is heated to 60°C. Titanium niobium sulfuric acid solution and 10 mol / L sodium hydroxide are added dropwise over a period of 3 hours so that the pH of the suspension becomes 2 to 3. After the total amount has been added dropwise, the pH is adjusted to near neutrality, and a polyacrylamide flocculant is added to settle the solid components. The supernatant is removed, filtered and washed, and dried at 110°C to obtain an intermediate containing 0.1 wt% (in terms of C) of organic matter derived from the flocculant. The intermediate is calcined at 750°C in nitrogen for 1 hour, and then calcined at 450°C in air to prepare titanium oxide particles. In the particle size measurement method using the above-mentioned scanning electron microscope, the obtained particles had an average primary particle size of 220 nm.

[0290] Subsequently, 50 parts of a phenolic resin (monomer / oligomer of a phenolic resin) as a bonding material (trade name: Plyophen J-325, manufactured by DIC Corporation, resin solid content: 60%, density after curing: 1.3 g / cm 2 ) was dissolved in 35 parts of 1-methoxy-2-propanol as a solvent to obtain a solution.

[0291] 60 parts of titanium oxide particles 1 are added to the solution, and the resulting mixture is placed in a vertical sand mill using 120 parts of glass beads having a number average primary particle size of 1.0 mm as a dispersion medium, and a dispersion treatment is carried out for 4 hours under the conditions of a dispersion temperature of 23±3°C and a rotation speed of 1500 rpm (circumferential speed 5.5 m / s) to obtain a dispersion. The glass beads are removed from the dispersion with a sieve. 0.01 parts of silicone oil (trade name: SH28 coating additive, manufactured by Dow Corning Toray Co., Ltd.) are used as a leveling agent and 8 parts of silicone resin particles (trade name: KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., average primary particle size: 2 μm, density: 1.3 g / cm 3 ) as a surface roughness imparting agent was added to the dispersion liquid from which the glass beads had been removed and stirred, and pressure filtration was performed using PTFE filter paper (trade name: PF060, Advantec Toyo Kaisha, Ltd.) to prepare a conductive layer coating liquid 1.

[0292] <Preparation of Undercoat Layer Coating Liquid 1>

[0293] 100 parts of rutile titanium oxide particles (average primary particle size: 50 nm, manufactured by Tayca) were mixed and stirred with 500 parts of toluene, 3.5 parts of vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.) were added thereto, and the mixture was dispersed for 8 hours in a vertical sand mill using glass beads with a diameter of 1.0 mm. After removing the glass beads, the toluene was distilled off by reduced pressure distillation and dried at 120°C for 3 hours to obtain rutile titanium oxide particles surface-treated with an organosilicon compound. When the volume of the obtained titanium oxide particles is a and the average primary particle size of the titanium oxide particles is b [μm], a / b = 15.6 was obtained. After the electrophotographic photosensitive member was manufactured, the value of a was obtained from a microscopic image of a cross section of the electrophotographic photosensitive member using a field emission scanning electron microscope (FE-SEM, trade name: S-4800, manufactured by Hitachi High-Tech Corporation).

[0294] 18.0 parts of rutile titanium oxide particles surface-treated with an organic silicon compound, 4.5 parts of methoxymethylated nylon (trade name: TORESIN EF-30T, manufactured by Nagase ChemteX Co., Ltd.), and 1.5 parts of a copolymerized nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Ltd.) were added to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol to prepare a dispersion.

[0295] This dispersion was dispersed for 5 hours with a vertical sand mill using glass beads having a diameter of 1.0 mm, and the glass beads were removed to prepare an undercoat layer coating liquid 1.

[0296] <Synthesis of Phthalocyanine Pigments>

[0297] <Synthesis example 1>

[0298] Under a nitrogen atmosphere, 100 g of gallium trichloride and 291 g of phthalonitrile were added to 1000 mL of α-chloronaphthalene. The mixture was reacted at 200°C for 24 hours, and the product was filtered. The resulting wet cake was heated and stirred with N,N-dimethylformamide at 150°C for 30 minutes, and then filtered. The filtered product was washed with methanol and then dried to obtain a chlorogallium phthalocyanine pigment with an 83% yield.

[0299] 20 g of the chlorogallium phthalocyanine pigment obtained by the above method was dissolved in 500 mL of concentrated sulfuric acid, stirred for 2 hours, and then added dropwise to a mixed solution of 1700 mL of ice-cooled distilled water and 660 mL of concentrated aqueous ammonia to precipitate the chlorogallium phthalocyanine pigment again. The mixture was thoroughly washed with distilled water and dried to obtain a hydroxygallium phthalocyanine pigment.

[0300] <Preparation of Charge Generating Layer Coating Liquid 1>

[0301] 0.5 parts of the hydroxygallium phthalocyanine pigment obtained in Synthesis Example 1, 7.5 parts of N,N-dimethylformamide (product code: D0722, manufactured by Tokyo Chemical Industry Co., Ltd.) and 29 parts of glass beads with a diameter of 0.9 mm were ground at 25°C for 24 hours using a sand mill (BSG-20, manufactured by AIMEX). At this time, the grinding disc rotated 1500 times per minute. The liquid thus treated was filtered through a filter (product number: N-NO.125T, pore size: 133 μm, manufactured by NBC Meshtec Inc.) to remove the glass beads. After adding 30 parts of N,N-dimethylformamide to the liquid, the mixture was filtered and the filtered product on the filter was thoroughly washed with n-butyl acetate. Then, the washed filtered product was vacuum dried to obtain 0.45 parts of hydroxygallium phthalocyanine pigment. The obtained pigment contains N,N-dimethylformamide.

[0302] Subsequently, 20 parts of the hydroxygallium phthalocyanine pigment obtained by the grinding treatment, 10 parts of polyvinyl butyral (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), 190 parts of cyclohexanone, and 482 parts of glass beads with a diameter of 0.9 mm were dispersed using a sand mill (K-800, manufactured by Igarashi Machinery Co., Ltd. (currently Imex Corporation), grinding wheel diameter: 70 mm, number of grinding wheels: 5) at a cooling water temperature of 18°C for 4 hours. At this time, the grinding wheel rotated 1800 times per minute. The glass beads were removed from the dispersion, and 444 parts of cyclohexanone and 634 parts of ethyl acetate were added to prepare a charge generation layer coating liquid 1.

[0303] <Preparation of Charge Transport Layer Coating Liquid 1>

[0304] (Preparation Example of Charge Transport Layer 1)

[0305] Next, prepare the following materials to prepare a mixed solvent.

[0306] - o-xylene: 25 parts by mass

[0307] -Methyl benzoate: 25 parts by mass

[0308] -Dimethoxymethane: 25 parts by mass

[0309] Furthermore, the following materials were dissolved in the mixed solvent to prepare a charge transport layer coating liquid 1.

[0310] - Charge transport material (hole transport material) represented by the following structural formula (C-1): 5 parts by mass

[0311] - Charge transport material (hole transport material) represented by the following structural formula (C-2): 5 parts by mass

[0312] - Polycarbonate (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation): 10 parts by mass

[0313] The charge transport layer coating liquid 1 was dip-coated on the charge generating layer 1 to form a coating film, and the coating film was dried at a drying temperature of 40° C. for 5 minutes to form a charge transport layer 1 having a film thickness of 15 μm.

[0314] [Chemical Formula 3]

[0315]

C-1

[0316]

[0317]

C-2

[0318]

[0319] (Preparation Example 1 of Particle-Containing Surface Layer)

[0320] The materials shown in Table 1 as PAA particles and PAB particles were prepared.

[0321] [Table 1]

[0322] particles Product Name Manufacturer Average primary particle size [nm] Particle 1 QSG-170 Shin-Etsu Chemical Co., Ltd. 170 Particle 2 QSG-80 Shin-Etsu Chemical Co., Ltd. 80 Particle 3 QSG-30 Shin-Etsu Chemical Co., Ltd. 30 Particle 4 QSG-100 Shin-Etsu Chemical Co., Ltd. 100 Particle 5 QSG-10 Shin-Etsu Chemical Co., Ltd. 10 Particle 6 KE-P30 Nippon Shokubai Co., Ltd. 300 Granules 7 KE-P50 Nippon Shokubai Co., Ltd. 500 Particles 8 hydrotalcite Kyowa Chemical Industry Co., Ltd. 250

[0323] <Preparation of Surface Layer Coating Liquid 1>

[0324] PAA particles: Silica particles ("QSG-170", manufactured by Shin-Etsu Chemical Co., Ltd.): 2.5 parts by mass

[0325] PAB particles: Silica particles ("QSG-80", manufactured by Shin-Etsu Chemical Co., Ltd.): 2.5 parts by mass

[0326] Monomer 1 having a polymerizable functional group (structural formula (2-1)): 0.75 parts by mass

[0327] Monomer 2 having a polymerizable functional group (structural formula (3-1)): 0.75 parts by mass

[0328] Siloxane-modified acrylic compound (trade name: SYMAC US270, manufactured by Toagosei Co., Ltd.): 0.1 parts by mass

[0329] 1-Propanol: 100.0 parts by mass

[0330] Cyclohexane: 100.0 parts by mass

[0331] The above materials were mixed and stirred in a stirring device for 6 hours to prepare a surface layer coating liquid 1.

[0332] <Preparation of Surface Layer Coating Liquids 2 to 25>

[0333] Surface layer coating liquids 2 to 25 were prepared in the same manner as in the preparation of the surface layer coating liquid 1, except that the types and amounts of the particles PAA, the particles PAB, and other particles were changed as shown in Table 2.

[0334] [Table 2]

[0335]

[0336] Note: In Table 2, "coating liquid" refers to "surface layer coating liquid." "Monomer 1 / Monomer 2" refers to "monomer 1 having a polymerizable functional group / monomer 2 having a polymerizable functional group."

[0337] <Preparation Example of Electrophotographic Photosensitive Member 1>

[0338] <Support>

[0339] An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as a support (cylindrical support).

[0340] <Conductive Layer>

[0341] The conductive layer coating liquid 1 was dip-coated on the support to form a coating film, and the coating film was heated at 150° C. for 30 minutes and cured to form a conductive layer having a film thickness of 22 μm.

[0342] <Base Coating>

[0343] The undercoat layer coating liquid 1 was dip-coated on the above conductive layer to form a coating film, and the coating film was heated at 100° C. for 10 minutes and cured to form an undercoat layer having a film thickness of 1.8 μm.

[0344] <Charge Generation Layer>

[0345] Charge generating layer coating liquid 1 was dip-coated on the above-mentioned undercoat layer to form a coating film, and the coating film was heated and dried at a temperature of 100° C. for 10 minutes to form a charge generating layer having a film thickness of 0.20 μm.

[0346] <Charge Transport Layer>

[0347] Charge transport layer coating liquid 1 was dip-coated on the above charge generating layer to form a coating film, and the coating film was heated and dried at a temperature of 120° C. for 30 minutes to form a charge transport layer having a film thickness of 21 μm.

[0348] <Surface layer>

[0349] The surface layer coating liquid 1 was dip-coated on the charge transport layer to form a coating film, and the coating film was heated at a temperature of 50°C for 5 minutes. Thereafter, under a nitrogen atmosphere, while rotating the support (irradiated body) at a speed of 300 rpm under the conditions of 65 kV accelerating voltage and 5.0 mA electron beam current, the coating film was irradiated with an electron beam for 2.0 seconds. The dose was 15 kGy. Thereafter, the temperature of the coating film was raised to 120°C under a nitrogen atmosphere. The oxygen concentration from electron beam irradiation to subsequent heat treatment was 10 ppm.

[0350] Next, the coating film was naturally cooled in air until the coating film temperature reached 25° C., and then heat-treated for 30 minutes at a coating film temperature of 120° C. to form a surface layer having a film thickness of 1.0 μm. The physical properties of the obtained electrophotographic photosensitive member are shown in Table 3.

[0351] <Preparation Examples of Electrophotographic Photosensitive Members 2 to 25>

[0352] Electrophotographic photosensitive members 2 to 25 were prepared in the same manner as in the preparation of electrophotographic photosensitive member 1, except that the surface layer coating liquid 1 in the preparation of electrophotographic photosensitive member 1 was changed according to the conditions in Table 2. The physical properties of the obtained electrophotographic photosensitive members 2 to 25 are shown in Table 3.

[0353] [Table 3]

[0354]

[0355] Note: In Table 3, “EP No.” means “electrophotographic photosensitive member number”. “Coating liquid” means “surface layer coating liquid used for preparation”. “Lamination state” means “Lamination state observed in cross section”. “PAA-peak DA” means “particle diameter DA of the peak top of PAA”. “Average distance between CAs” means “average value of the distance between the centers of convex portions CA”. “SD between CAs” means “standard deviation of the distance between the centers of convex portions CA”. “Average thickness T” means “average film thickness”. “PAB-peak DB” means “particle diameter DB of the peak top of PAB”. “Convex portion ratio” means “the ratio of the number of convex portions CA to the number of convex portions derived from particles PAA”. “Half-value width PAA” means “half-value width of PAA distribution”. “Circularity of PAA” means “circularity of particles PAA”. “Particle ratio in surface” means “content ratio of particles contained in the surface layer”. “MONO” means “monolayer”. “MULTI” means “multilayer”.

[0356] <Manufacturing of Intermediate Transfer Member>

[0357] <Preparation Example of Intermediate Transfer Member 1>

[0358] <Preparation of base layer>

[0359] A polyethylene naphthalate resin (PEN) in which carbon black as a resistance modifier was dispersed was stretched and blown to obtain a bottle-shaped molded body. This bottle-shaped molded body was cut using an ultrasonic cutter to form an endless belt. The resulting endless belt made of PEN resin and having a thickness of 60 μm was used as the base layer of the intermediate transfer member 1.

[0360] <Preparation of Coating Liquid for Surface Layer Formation>

[0361] In a container shielded from ultraviolet light, 50 parts of PTFE particles having a primary particle size of 200 nm (Lubron L-2: manufactured by Daikin Industries, Ltd.), 100 parts of an acrylic copolymer containing unsaturated double bonds (Opster Z7501: manufactured by JSR Corporation), and 25 parts of an isopropyl alcohol sol containing zinc antimonate particles (Cellnax CX-Z210IP: manufactured by Nissan Chemical Industries, Ltd.) were mixed. The mixed liquid was dispersed and mixed using a high-pressure emulsifying disperser to prepare an ultraviolet-curable resin composition, which was used as a coating liquid for forming a surface layer.

[0362] <Preparation of Surface Layer>

[0363] In a coating environment at a temperature of 25° C. and a humidity of 60% RH, the coating liquid for forming the surface layer was dip-coated on the above-prepared base layer. Ten seconds after the coating was completed, an ultraviolet irradiation device (trade name: UE06 / 81-3, manufactured by Eye Graphics, cumulative light intensity: 1000 mJ / cm) was used in the same environment to irradiate the substrate. 2 ) The coating film of the coating liquid for forming the surface layer was irradiated with ultraviolet rays to cure the acrylic copolymer containing unsaturated double bonds. In this manner, an intermediate transfer member 1 was obtained in which a surface layer mainly composed of a cured acrylic resin and having a thickness of 0.5 μm was formed on the base layer. The volume resistivity of the intermediate transfer member 1 was 1.0×10 10 Ω·cm. The circumference is 712mm and the width is 248mm.

[0364] <Preparation of Intermediate Transfer Members 2 to 4>

[0365] Intermediate transfer members 2 and 3 were obtained in the same manner as intermediate transfer member 1 except that the surface roughness was changed by changing the mixing amount of PTFE particles contained in the coating liquid for surface layer formation in preparation of the surface layer of intermediate transfer member 1 as shown in Table 4.

[0366] The intermediate transfer member 1 is embossed to obtain an intermediate transfer member 4 in which grooves are formed along the intermediate transfer member moving direction.

[0367] Table 4 shows the values of the arithmetic mean curvatures Spc of the peak points of the intermediate transfer members 1 to 4 .

[0368] [Table 4]

[0369]

[0370] <Effect of this example>

[0371] In order to demonstrate the effect of this example, evaluation was performed under the following conditions.

[0372] In an environment with a temperature of 25°C and a humidity of 60% RH, "Letter" size Xerox Vitality paper (manufactured by Xerox Corporation, basis weight: 75 g / m 2 ) was used as the transfer material S in the image forming apparatus 100. The conveying speed of the transfer material S was 300 mm / sec, the peripheral speed of the intermediate transfer member 8 was 300 mm / sec, and the peripheral speed of the electrophotographic photosensitive member 1 was 291 mm / sec. That is, the peripheral speed difference between the intermediate transfer member 8 and the electrophotographic photosensitive member 1 was set to 3%. In addition, as an evaluation of image blur, a cyan halftone image (toner application amount: 0.2 mg / cm 2 ), and image blurring was confirmed. Note that the electrophotographic photosensitive members 1 in all the process cartridges for yellow, magenta, cyan, and black were the same.

[0373] To confirm image blur in the latter half of the imaging device 100's lifespan, a sheet durability test was conducted on 200,000 sheets of full-color 1.0% imagery. The temperature and humidity, type of transfer material (S), and various speeds were set to the same conditions as those used for the image blur evaluation. After 10,000 sheets had been passed through, a halftone cyan image was printed and image blur was confirmed. Evaluation criteria B was considered acceptable for practical use.

[0374] (Evaluation Criteria)

[0375] A: No image blur

[0376] B: Extremely slight image blurring occurs.

[0377] C: Clearly visually recognizable image blurring occurs.

[0378] Table 5 shows an example of evaluation of image blur in the initial stage and after durability (after 10,000 paper passes), and Table 6 shows the results of comparative examples.

[0379] In Examples 1 to 24, the occurrence of image blur was suppressed both in the initial stage and after the durability test for the reasons described above. In Comparative Examples 1, 3, 4, and 6 to 10, initial image blur was not a problem, but after the durability test, image blur occurred due to detachment of particles from the electrophotographic photosensitive member. Furthermore, in Comparative Examples 2 and 5, due to the small particle diameter DA in the electrophotographic photosensitive member, a sufficient friction reduction effect could not be achieved, and image blur occurred from the outset.

[0380] [Table 5]

[0381]

[0382] In Table 5, “EP No.” means “electrophotographic photosensitive member number.” “IT No.” means “intermediate transfer member number.” “Particle diameter DA” means “<electrophotographic photosensitive member> particle diameter.” “2×1 / Spc” means “<intermediate transfer member> 2×1 / Spc.”

[0383] [Table 6]

[0384]

[0385] In Table 6, “EP No.” means “electrophotographic photosensitive member number.” “IT No.” means “intermediate transfer member number.” “Particle diameter DA” means “<electrophotographic photosensitive member> particle diameter.” “2×1 / Spc” means “<intermediate transfer member> 2×1 / Spc.”

[0386] As described above, according to the present invention, even in the latter half of the life of the image forming apparatus, the effect of reducing the friction between the electrophotographic photosensitive member and the intermediate transfer member can be maintained, and the occurrence of image blur can be suppressed.

[0387] In this example, use Figure 1 The present invention is not shown as a drum-less cleaner system having a primary transfer residual toner cleaning device. However, a primary transfer residual toner cleaning device may also be provided. For example, the effects of the present invention can also be achieved by using a so-called blade cleaning system in which a rubber blade is brought into contact with the electrophotographic photosensitive member to recover the primary transfer residual toner.

[0388] Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings. However, depending on the configuration and various conditions of the device to which the present invention is applied, the size, material, shape, relative arrangement, etc. of the components described in the following examples should be appropriately changed. Therefore, unless otherwise specified, the scope of the present invention is not limited. Although multiple features are described in the examples, not all of these multiple features are essential to the present invention, and these multiple features can be arbitrarily combined.

[0389] (Structure of Imaging Apparatus)

[0390] Figure 9 : This is a schematic diagram of the configuration of an image forming apparatus equipped with the process cartridge of this example, and shows a cross-section viewed from the front of the image forming apparatus. In the following description, the letters YMCK provided at the end of the reference numerals represent the toner colors, and matters common to the four colors will be omitted. As the image forming apparatus, an electrophotographic laser beam printer capable of forming images at a process speed of 210 mm / s and 600 dpi, compatible with legal-sized paper, was used.

[0391] Figure 9 The imaging device shown includes a detachable process cartridge P. These four process cartridges P have the same structure. The difference is that an image is formed by the toner of the color of the toner contained in the process cartridge (i.e., yellow (Y), magenta (M), cyan (C), and black (K)). Hereinafter, the contents common to each color are indicated by a subscript representing the color, and individual descriptions will be omitted. For example, when distinguishing between process cartridges of each color, the process cartridges will be referred to as process cartridge PY, process cartridge PM, process cartridge PC, and process cartridge PK, and the common description for each color will simply refer to process cartridge P.

[0392] The process box P includes a toner container 23. The image forming apparatus also includes a photosensitive drum 1 as an image carrier. The image forming apparatus also includes a charging roller 2 and a developing roller 3. The photosensitive drum 1 is a cylindrical axial ( Figure 9 The photosensitive drum 1 is a cylindrical body with a width (depth direction) of 255 mm (hereinafter referred to as the longitudinal length) and a diameter of 24 mm, and is formed with multiple functional layers. The construction of the photosensitive drum 1 will be described in detail later. The axial direction of the photosensitive drum 1 is the longitudinal direction. The longitudinal direction is the common axial direction of various components such as the photosensitive drum 1, the charging roller 2, the developing roller 3, the primary transfer roller 6, and the multiple tension rollers such as the drive roller 9, the tension roller 10, and the counter roller 28.

[0393] The charging roller 2 is a rubber roller having a longitudinal width of 230 mm and a diameter of 8 mm, wherein conductive rubber is formed on a plated free-cutting steel shaft. The charging roller 2 is pressed against the photosensitive drum 1 with a predetermined pressure to form a charging nip, and rotates as the photosensitive drum rotates.

[0394] The developing roller 3 is a rubber roller having a longitudinal width of 235 mm and a diameter of 12 mm, wherein a conductive rubber is formed on a plated free-cutting steel shaft. The developing roller 3 is pressed against the photosensitive drum 1 with a predetermined pressure, forming a developing nip with an intrusion of slightly less than 0.1 mm. The developing roller 3 is driven by a driving device (not shown) so as to be able to rotate at a speed higher than the speed of the photosensitive drum.

[0395] The laser unit 7 is positioned below the process cartridge P and exposes the photosensitive drum 1 based on an image signal. By applying a predetermined negative voltage to the charging roller 2, the photosensitive drum 1 is charged to a predetermined negative dark potential (Vd). The laser unit 7 then emits a laser beam in the imaging section based on the image signal, reducing the potential in the exposed portion of the photosensitive drum 1 and forming an electrostatic latent image with a predetermined bright potential (Vl). By applying a predetermined negative voltage (Vdc) to the developing roller 3 and providing an appropriate potential difference between the Vd and Vl sections, the toner on the developing roller 3 transfers only to the Vl section when the electrostatic latent image passes through the developing nip, and the electrostatic latent image is visualized. The difference between Vdc and Vl is called the development contrast, and this potential difference is used to control the amount of toner developed from the developing roller 3 onto the photosensitive drum 1. The difference between Vd and Vdc is called the background contrast, and this potential difference is used to recover residual toner from the primary transfer process from the photosensitive drum 1 to the developing roller 3. This example adopts the following settings, in which the development contrast and the background contrast are 200V by setting Vd=-550V, Vl=-150V, and Vdc=-350V.

[0396] The toner used in this example is formed by externally adding silica fine particles having an average particle size of 20 nm to toner particles having an average particle size of 6.4 μm, and is negatively charged. The average particle size is an average particle size obtained from the particle volume and can be measured by, for example, the Coulter method.

[0397] The intermediate transfer belt unit includes an intermediate transfer belt 8 as an endless transfer belt, and a driving roller 9 , a tension roller 10 , and an opposing roller 28 as tension rollers.

[0398] The intermediate transfer belt 8 is an endless belt having a longitudinal width of 250 mm and a circumference of 712 mm, and is made of a two-layer resin material, in which a base layer having a thickness of 60 μm is coated with a resin surface layer having a thickness of 2 μm. The intermediate transfer belt 8 is stretched around three axes: a 24 mm diameter drive roller 9, a 24 mm diameter tension roller 10, and a 16 mm diameter opposing roller 28, and is stretched by the tension roller 10 with a total tension of 100 N.

[0399] The base layer of intermediate transfer belt 8 is a seamless belt-like layer obtained by extruding the resulting mixture by adding an ion conductive agent as a conductive agent to polyethylene naphthalate resin (PEN) and polyetheresteramide (PEEA). Although PEN and PEEA resins are used as the base layer materials, other materials can be used as long as they are thermoplastic resins. For example, materials such as polyester, polycarbonate, polyarylate, polyetheretherketone (PEEK), acrylonitrile-butadiene-styrene copolymer (ABS), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVdF), and mixed resins thereof can be used. As the ion conductive material of the conductive agent, an alkali metal salt is used.

[0400] The surface layer of the intermediate transfer belt 8 is an acrylic resin layer obtained by dip-coating a base layer with a curable composition (in which a multifunctional acrylic monomer, a photopolymerization initiator, and conductive metal oxide particles are dissolved and dispersed in a solvent) and irradiating the base layer with ultraviolet rays. As a method of coating the surface layer, other methods may be used as long as a uniform film can be formed, and spray coating, flow coating, curtain coating, roller coating, spin coating, etc. can be used.

[0401] The primary transfer roller 6, serving as the primary transfer member (transfer member), is arranged on the inner side of the intermediate transfer belt 8 (i.e., the inner peripheral side of the intermediate transfer belt) so as to face the photosensitive drum 1, and a transfer voltage is applied by a voltage applying device (not shown). The primary transfer roller 6 is a 6 mm diameter, plated, free-cutting steel shaft, and presses the intermediate transfer belt 8 against the photosensitive drum 1 with a contact pressure of 5 N to form a primary transfer nip. In order to stably form the shape of the primary transfer nip, it is preferable that the primary transfer roller 6 is arranged so as to be offset downstream in the direction of rotation of the intermediate transfer belt relative to the center position of the photosensitive drum 1. In this configuration, by offsetting the intermediate transfer belt 8 downstream by approximately 2 mm, the intermediate transfer belt 8 can be stably wound around the photosensitive drum 1 with a width of approximately 0.8 mm.

[0402] The optical sensor 27 is arranged at each position 100 mm on both sides from the center of the intermediate transfer belt longitudinal width, and is configured to detect a calibration patch (test image) formed on the intermediate transfer belt 8 with the drive roller 9 as an opposing member.

[0403] By rotating each photosensitive drum in the direction of the arrow, rotating the intermediate transfer belt 8 in the direction of the arrow Z by an intermediate transfer belt driving device (not shown), and further applying a positive voltage to the primary transfer roller 6, the toner image formed on the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 8. Starting with the toner image on the photosensitive drum 1Y, the toner images are sequentially primarily transferred onto the intermediate transfer belt 8 and conveyed to a secondary transfer portion (secondary transfer nip) formed by the secondary transfer roller 11 and the opposing roller 28 as a secondary transfer member in a state where the toner images of four colors are overlapped.

[0404] The feeding and conveying device 12 includes a feeding roller 14 that feeds the recording material K from a feeding cassette 13 storing the recording material K, and a conveying roller pair 15 that conveys the fed recording material K. The recording material K conveyed from the feeding and conveying device 12 is then conveyed to the secondary transfer portion by a registration roller pair 16 .

[0405] In order to transfer the toner image from the intermediate transfer belt 8 to the recording material K, a positive voltage is applied to the secondary transfer roller 11. As a result, the toner image on the intermediate transfer belt 8 can be secondarily transferred to the conveyed recording material K. The recording material K to which the toner image has been transferred is conveyed to the fixing device 17 and is heated and pressurized by the fixing film 18 and the pressure roller 19 to fix the toner image on the surface. The recording material K after the fixation is discharged by the discharge roller pair 20.

[0406] After the toner image is transferred to the recording material K, the primary transfer residual toner remaining on the surface of the photosensitive drum 1 is electrostatically recovered in the developing nip. The primary transfer residual toner has a negative polarity, and in the charging nip, the surface potential of the charging roller has a higher negative potential than the drum surface potential, so the primary transfer residual toner remains on the drum surface. On the other hand, at the developing nip, due to the background contrast between Vd and Vdc, the toner is transferred from the photosensitive drum 1 with a high potential to the developing roller 3 with a low potential, and the primary transfer residual toner is recovered. In this example, a so-called cleaner-less system is adopted, which does not include a cleaning device for removing the primary transfer residual toner on the photosensitive drum by a scraper or the like.

[0407] Furthermore, the secondary transfer residual toner is mechanically scraped off by a secondary cleaning blade 21 as a cleaning member after the intermediate transfer belt 8 rotates in the direction of arrow Z, and is recovered in the waste toner recovery container 22. As the secondary cleaning blade 21, a galvanized steel plate having a thickness of 3 mm to which a polyurethane rubber blade having a thickness of 2 mm and a 77-degree urethane rubber according to JIS K 6253 is attached is used, and the galvanized steel plate is pressed against the tension roller 10 in the reverse direction via the intermediate transfer belt 8 with a pressing force of a linear pressure of approximately 0.49 N / cm and a total pressure of approximately 11.3 N.

[0408] In addition, the control substrate 25 is a substrate on which a circuit for controlling the image forming apparatus is mounted, and a CPU 26 serving as a control unit is mounted. The CPU 26 collectively controls the operation of the image forming apparatus, such as control of an intermediate transfer belt drive motor serving as a drive source for the intermediate transfer belt 8 associated with conveyance of the recording material K, a drive source (not shown) for the feed and conveyance device 12, the registration roller pair 16, and the fixing device 17, and a drum motor (not shown) serving as a drive source for the process cartridge P, control of various image signals associated with image formation, density correction control based on a detection result of the optical sensor 27, and other controls associated with fault detection.

[0409] (Photosensitive drum)

[0410] The photosensitive drum 1 of the present invention includes a support and a surface layer 32 including a photosensitive layer and particles provided on the support. The photosensitive drum 1 according to the present invention can be used as a cylindrical photosensitive drum, wherein the photosensitive layer and the surface layer 32 are formed on the cylindrical support; however, it can also be a belt or sheet.

[0411] Examples of production methods include preparing a coating solution for each layer described below, applying the desired layers in the order described, and drying. Examples of coating methods include dip coating, spray coating, inkjet coating, roll coating, die coating, knife coating, curtain coating, wire coating, and ring coating. Among these, dip coating is preferred from the perspectives of efficiency and productivity.

[0412] Each layer is described below.

[0413] <Support>

[0414] In the photosensitive drum 1 of the present invention, the support is preferably a conductive support having conductivity. Examples of the shape of the support include cylindrical, belt-shaped, sheet-shaped, etc. Among them, a cylindrical support is preferred. The surface of the support may be subjected to electrochemical treatment (e.g., anodizing), sandblasting, cutting treatment, etc. The material of the support is preferably metal, resin, glass, etc. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, alloys thereof, etc. Among them, an aluminum support using aluminum is preferred. In addition, conductivity can be imparted to the resin or glass by treatments such as mixing or coating with a conductive material.

[0415] <Conductive Layer>

[0416] The photosensitive drum 1 of the present invention may include a conductive layer on the support. Providing the conductive layer can shield scratches and unevenness on the support surface and control light reflection on the support surface. The conductive layer preferably contains conductive particles and a resin. Examples of materials for the conductive particles include metal oxides, metals, and carbon black.

[0417] Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of metals include aluminum, nickel, iron, nickel chromium, copper, zinc, silver, etc.

[0418] Among them, metal oxides are preferably used as the conductive particles, and titanium oxide, tin oxide, or zinc oxide is more preferably used.

[0419] When using metal oxide as conductive particles, the surface of the metal oxide can be treated with a silane coupling agent, or the metal oxide can be doped with an element such as phosphorus or aluminum or its oxide. In addition, the conductive particles can have a stacked structure in which uncoated particles (such as titanium oxide, barium sulfate, zinc oxide) are coated with a metal oxide having a different composition from that of the uncoated particles. The example of coating includes metal oxide (such as tin oxide). When using metal oxide as conductive particles, the average primary particle size is preferably at least 1 nm and not more than 500 nm, more preferably at least 3 nm and not more than 400 nm.

[0420] 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.

[0421] The conductive layer may also contain a masking agent such as silicone oil, resin particles or titanium oxide. The average film thickness of the conductive layer is preferably at least 1 μm and not more than 50 μm, particularly preferably at least 3 μm and not more than 40 μm. The conductive layer can be formed by preparing a conductive layer coating solution containing the above-mentioned materials and a solvent, forming a coating film, and drying the coating film. Examples of solvents used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, etc. Examples of dispersion methods for dispersing conductive particles in the conductive layer coating solution include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0422] <Base Coating>

[0423] In the photosensitive drum 1 of the present invention, an undercoat layer may be provided on the support or the conductive layer. The average film thickness of the undercoat layer is preferably at least 0.1 μm and not more than 50 μm, more preferably at least 0.2 μm and not more than 40 μm, and particularly preferably at least 0.3 μm and not more than 30 μm.

[0424] Examples of the resin of the primer layer include polyacrylic acid resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyethylene oxide resins, polypropylene oxide resins, ethyl cellulose resins, methyl cellulose resins, polyamide resins, polyamic acid resins, polyurethane resins, polyimide resins, polyamideimide resins, polyvinyl phenolic resins, melamine resins, phenolic resins, epoxy resins, and alkyd resins. The resin may have a structure in which a resin having a polymerizable functional group and a monomer having a polymerizable functional group are cross-linked.

[0425] Furthermore, the undercoat layer may contain an inorganic compound or an organic compound in addition to the resin.

[0426] Examples of inorganic compounds include metals, oxides, and salts.

[0427] Examples of metals include gold, silver, and aluminum. Examples of oxides include zinc oxide, white lead, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, indium oxide, tin oxide, and zirconium oxide. Examples of salts include barium sulfate and strontium titanate.

[0428] These inorganic compounds may be present in the film in a particle state. The number average particle size of the particles is preferably at least 1 nm and not more than 500 nm, more preferably at least 3 nm and not more than 400 nm.

[0429] These inorganic compounds may have a laminated structure including core particles and a coating layer of coating particles.

[0430] The surfaces of these inorganic compounds may be treated with silicone oil, silane compounds, silane coupling agents, other organic silicon compounds, organic titanium compounds, etc. In addition, elements such as tin, phosphorus, aluminum, niobium, etc. may be doped.

[0431] Examples of organic compounds include electron transport compounds and conductive polymers. Examples of conductive polymers include polythiophene, polyaniline, polyacetylene, polyphenylene and polyethylenedioxythiophene. Examples of electron transport materials include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silylheterocyclopentadiene compounds and boron-containing compounds. The electron transport material has a polymerizable functional group and can be cross-linked with a resin having a functional group capable of reacting with the functional group. Examples of polymerizable functional groups include hydroxyl, thiol, amino, carboxyl, vinyl, acryloyl, methacryloyl, epoxy and the like. These organic compounds can be present in the film in a particulate state, or their surface can be treated.

[0432] Various additives (such as leveling agents (e.g., silicone oil), plasticizers, thickeners) can be added to the primer layer. The primer layer is obtained by preparing a primer coating solution containing the above-mentioned materials, applying the coating solution to a support or a conductive layer, and then drying or curing the coating film. Examples of solvents used in the preparation of the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like. Examples of dispersion methods for dispersing particles into the coating solution include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0433] <Photosensitive Layer>

[0434] Photosensitive layers are mainly divided into (1) laminated photosensitive layers and (2) single-layer photosensitive layers. (1) Laminated photosensitive layers include a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material. (2) Single-layer photosensitive layers include a photosensitive layer containing both a charge generating material and a charge transporting material.

[0435] (1) Laminated photosensitive layer

[0436] The laminated photosensitive layer includes a charge generating layer and a charge transporting layer.

[0437] (1-1) Charge Generation Layer

[0438] The charge generating layer preferably contains a charge generating material and a resin.

[0439] Examples of charge generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, phthalocyanine pigments, etc. Among them, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.

[0440] The content of the charge generating material in the charge generating layer is preferably at least 40% by mass and not more than 85% by mass, more preferably at least 60% by mass and not more than 80% by mass, relative to the total mass of the charge generating layer.

[0441] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, etc. Among them, polyvinyl butyral resin is more preferred.

[0442] The charge generation layer may further contain additives such as antioxidants, ultraviolet absorbers, etc. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, and the like.

[0443] The charge generation layer can be formed by preparing a charge generation layer coating solution containing the above-mentioned materials and a solvent, forming a coating film on the undercoat layer, and drying the coating film. Examples of the solvent used in the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and the like.

[0444] The film thickness of the charge generating layer is preferably at least 0.1 μm and not more than 1.5 μm, more preferably at least 0.15 μm and not more than 1.0 μm.

[0445] (1-2) Charge transport layer

[0446] The charge transport layer preferably contains a charge transport material and a resin.

[0447] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, resins having groups derived from these materials, etc. Among them, triarylamine compounds and benzidine compounds are preferred, and compounds having the following structure are suitably used.

[0448] [Chemical Formula 4]

[0449]

[0450] (In formula (1), R 1 -R 10 Each independently represents a hydrogen atom or a methyl group.)

[0451] Examples of the structure represented by formula (1) are shown in formula (1-1) to formula (1-10). Among them, the structures represented by formula (1-1) to formula (1-6) are more preferable.

[0452] [Chemical Formula 5]

[0453]

[0454] The content of the charge transport material in the charge transport layer is preferably at least 25% by mass and not more than 70% by mass, more preferably at least 30% by mass and not more than 55% by mass, relative to the total mass of the charge transport layer.

[0455] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among them, polycarbonate resin and polyester resin are preferred. Polyester resin is particularly preferably polyarylate resin.

[0456] 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.

[0457] Furthermore, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slip-imparting agents, and wear resistance enhancers. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, silicone-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0458] The charge transport layer can be formed by preparing a charge transport layer coating solution containing the above-mentioned materials and a solvent, forming a coating film on the charge generating layer, and drying the coating film. Examples of solvents used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Of these solvents, ether solvents or aromatic hydrocarbon solvents are preferred.

[0459] The film thickness of the charge transport layer is preferably at least 3 μm and no more than 50 μm, more preferably at least 5 μm and no more than 40 μm, and particularly preferably at least 10 μm and no more than 30 μm. As described later, when the charge transport layer is the surface layer 32 of the photosensitive drum 1, particles forming a convex shape are formed on the surface of the charge transport layer. Usable particle materials, suitable convex shapes, etc. will be described in detail in the description of the surface layer 32.

[0460] (2) Single-layer photosensitive layer

[0461] A single-layer photosensitive layer can be formed by preparing a photosensitive layer coating solution containing a charge generating material, a charge transporting material, a resin, and a solvent, forming a coating film on the undercoat layer, and drying the coating film. Examples of the charge generating material, the charge transporting material, and the resin are the same as those in the above-mentioned "(1) Laminated Photosensitive Layer". The film thickness of the single-layer photosensitive layer is preferably at least 10 μm and not more than 45 μm, more preferably at least 25 μm and not more than 35 μm.

[0462] <Surface layer>

[0463] The photosensitive drum 1 of the present invention includes a surface layer 32 containing particles. By setting the convex shape caused by the contained particles within an appropriate range, the adhesion between the toner and the photosensitive drum 1 can be reduced, and the transfer efficiency can be improved.

[0464] The adhesion between the toner and the photosensitive drum 1 can be broadly categorized as electrostatic adhesion and non-electrostatic adhesion. Since the mirror image force is the primary factor in electrostatic adhesion, it largely depends on the toner's charge. The magnitude of the mirror image force is proportional to the toner's charge and inversely proportional to the square of the distance from the surface of the photosensitive drum 1 to which the toner adheres. The mirror image force can be reduced by forming convex shapes on the surface layer 32 of the photosensitive member and ensuring a sufficient distance between the toner and the surface of the photosensitive drum 1. Specifically, ensuring the height of the convex shapes is effective in reducing the mirror image force. In other words, increasing the particle size used to form the convex portions and exposing the particles from the surface layer 32 is effective.

[0465] On the other hand, in order to reduce the non-electrostatic adhesion force, it is necessary to reduce the van der Waals force. To reduce the van der Waals force, it is effective to geometrically reduce the contact area between the colorant and the surface of the photosensitive drum 1. To reduce the contact area, it is effective to reduce the number of contact points between the colorant and the photosensitive drum 1 and to reduce the area at the contact points between the colorant and the photosensitive drum 1. To reduce the former (i.e., the number of contact points), it is effective to discretely form convex shapes within a range smaller than the toner particle size. To reduce the latter (i.e., the contact area), it is effective to reduce the curvature radius of the convex shape. In other words, it is effective to reduce the particle size used to form the convex portion and to discretely form the convex portion within a range below the toner particle size.

[0466] Furthermore, in order to maintain the durability of the convex shape, it is effective to suppress the particles from being exposed from the surface layer 32 .

[0467] In the photosensitive drum 1, process cartridge, and image forming apparatus using the same of the present invention, by combining an appropriate convex shape with an appropriate image forming apparatus configuration for these components, the convex shape can be maintained throughout the durability period, and the effect of improving transfer efficiency can be achieved over a long period of time. The appropriate convex shape and its combination with the image forming apparatus configuration will be described in detail later, and the constituent materials of the surface layer of the photosensitive drum 1 will be described.

[0468] The surface layer 32 of the photosensitive drum 1 of the present invention contains particles for forming a convex shape as described above. The material of the particles is not particularly limited. Organic resin particles (e.g., acrylic resin particles), inorganic particles (e.g., aluminum oxide, silicon dioxide, titanium oxide), and organic-inorganic hybrid particles can be used.

[0469] Furthermore, to enhance the charge transport capability of the surface layer 32, conductive particles or a charge transport material may be added to the surface layer coating solution. Conductive particles may be used as conductive pigments for the conductive layer described above. Charge transport materials may be used as the charge transport substances described above. Furthermore, additives may be added to enhance various functions. Examples of additives include conductive particles, antioxidants, ultraviolet absorbers, plasticizers, and leveling agents.

[0470] Examples of the organic resin particles include cross-linked polystyrene particles, cross-linked acrylic resin particles, phenol resin particles, melamine resin particles, polyethylene particles, polypropylene particles, acrylic resin particles, polytetrafluoroethylene particles, and silicone particles.

[0471] The acrylic resin particles contain polymers of acrylate or methacrylate. Among them, styrene acrylic resin particles are more preferred. There are no particular restrictions on the degree of polymerization of the acrylic resin and styrene acrylic resin, and whether the resin is thermoplastic or thermosetting.

[0472] The polytetrafluoroethylene particles may be particles mainly composed of tetrafluoroethylene resin, and may further contain chlorotrifluoroethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, dichlorodifluoroethylene resin, and the like.

[0473] Examples of the organic-inorganic hybrid particles include polymethylsilsesquioxane particles containing a siloxane bond.

[0474] As the particles of the surface layer 32 of the photosensitive drum 1 of the present invention, it is more preferable to use inorganic particles that have low elasticity and are advantageous in point contact with the toner.

[0475] Examples include particles of magnesium oxide, zinc oxide, lead oxide, tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, vanadium oxide, copper aluminum oxide, tin oxide doped with antimony ions, and hydrotalcite. These particles can be used alone or in combination of two or more. The inorganic particles are preferably silica particles.

[0476] As the silica particles, known silica particles can be used, and either dry silica particles or wet silica particles can be used. Wet silica particles obtained by a sol-gel method (hereinafter also referred to as "sol-gel silica") are more preferred.

[0477] In the sol-gel silica used for the particles contained in the surface layer 32 of the photosensitive drum 1 of the present invention, the surfaces of the particles may be hydrophilic, or the surfaces of the particles may be hydrophobized.

[0478] Examples of hydrophobic treatment methods include a sol-gel method in which the solvent is removed from a silica sol suspension, the silica sol suspension is dried, and then the silica sol suspension is treated with a hydrophobic agent, and a method in which a hydrophobic agent is directly added to the silica sol suspension and the silica sol suspension is treated simultaneously with drying. The method of directly adding a hydrophobic agent to the silica sol suspension is preferred from the viewpoints of controlling the half-value width of the particle size distribution and controlling the saturated water adsorption amount.

[0479] By subjecting the particles contained in the surface layer 32 of the photosensitive drum 1 of the present invention to a hydrophobizing treatment, it is possible to control the exposure state of the particles in the surface layer 32. Examples of the hydrophobizing agent include the following.

[0480] Chlorosilanes, such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tert-butyldimethylchlorosilane, and vinyltrichlorosilane;

[0481] Alkoxysilanes, such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane , isobutyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-(2-aminoethyl)aminopropylmethyldimethoxysilane;

[0482] Silazanes, such as hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyltetramethyldisilazane, and dimethyltetravinyldisilazane;

[0483] Silicone oils such as dimethyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, methanol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, and terminally reactive silicone oil;

[0484] Siloxanes, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, and octamethyltrisiloxane;

[0485] Fatty acids and their metal salts include undecanoic acid, lauric acid, tridecanoic acid, dodecanoic acid, myristic acid, palmitic acid, pentadecanoic acid, stearic acid, heptadecanoic acid, long-chain fatty acids (such as arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc.), and salts of fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

[0486] Among them, alkoxysilane, silazane and silicone oil are preferably used because they can be easily hydrophobized. These hydrophobizing agents can be used alone or in combination of two or more.

[0487] The Young's modulus of the particles contained in the surface layer 32 of the photosensitive drum 1 of the present invention is preferably 0.60 GPa or more. When the Young's modulus of the particle surface is less than 0.60 GPa, the contact area between the toner surface and the particle surface increases when contacting the toner, and transferability may deteriorate.

[0488] As the photosensitive drum layer configuration for obtaining the effects of the present invention, three layer configurations can be envisaged. This will be referred to Figure 10 (A) Figure 10 (B) and Figure 10 (C) is described.

[0489] Layer structure 1: The photosensitive drum 1 has a support 105 and a photosensitive layer on the support, wherein the surface layer 32 of the photosensitive drum 1 contains particles 101, the photosensitive layer has a charge generating layer 104 and a charge transporting layer 103 on the charge generating layer, and the charge transporting layer is the surface layer 32 ( Figure 10 (A)).

[0490] Layer structure 2: The photosensitive drum 1 has a support 205 and a photosensitive layer on the support, wherein the surface layer 32 of the photosensitive drum 1 contains particles 201, the photosensitive layer has a charge generating layer 204 and a charge transporting layer 203 on the charge generating layer, and the photosensitive drum 1 further has a protective layer 202 on the photosensitive layer, and the protective layer is the surface layer 32 ( Figure 10 (B)).

[0491] Layer structure 3: The photosensitive drum 1 has a support 305 and a photosensitive layer on the support, wherein the surface layer 32 of the photosensitive drum 1 contains particles 301, the photosensitive layer is a single-layer photosensitive layer 304, and the photosensitive drum 1 further has a protective layer 302 on the photosensitive layer, and the protective layer is the surface layer 32 ( Figure 10 (C)).

[0492] From the viewpoint of easiness in controlling the arrangement of the particles of the surface layer 32 , the layer configuration 1 or the layer configuration 2 is preferable for achieving both transferability and durability.

[0493] (Photosensitive drum evaluation method)

[0494] In the photosensitive drum 1 of the present invention, maintaining the convex shape caused by the contained particles within an appropriate range is an important factor in improving transfer efficiency by reducing the adhesion between the toner and the photosensitive drum 1, and maintaining performance through durability. Therefore, it is necessary to appropriately evaluate and control the particle size of the particles that form the convex shape, their exposure to the photosensitive drum, the concavo-convex shape of the exposed particles, and the Young's modulus of the exposed particles. Each evaluation method will be described below.

[0495] <Method for measuring volume average particle size of particles>

[0496] The volume average particle size of the particles was measured using a Zetasizer Nano-ZS (manufactured by Malvern Instruments Ltd.). The device is capable of measuring particle size by dynamic light scattering. First, the sample to be tested was diluted and adjusted to a solid-to-liquid ratio of 0.10 mass % (± 0.02 mass %), collected in a quartz cell, and placed in a measuring cell. When the sample was an inorganic fine particle, water or a methyl ethyl ketone / methanol mixed solvent was used as the dispersion medium. When the sample was an external additive for resin particles or a toner, water was used as the dispersion medium. The refractive index of the sample, the refractive index of the dispersion solvent, the viscosity, and the temperature were input as measurement conditions and measured using the control software Zetasizer software 6.30. Dn was used as the number average particle size.

[0497] The refractive index of the particles adopts the "Refractive Index of Solids" described on page 517 of Volume II of the "Chemical Handbook" Basic Edition Revised 4th Edition (edited by the Chemical Society of Japan, Maruzen Co., Ltd.). As the refractive index of the resin particles, the refractive index of the resin used for the resin particles is adopted as the refractive index contained in the control software. However, when there is no included refractive index, the value listed in the polymer database of the National Institute for Materials Science is used. The refractive index of the external additive of the toner is calculated by taking the weight average of the refractive index of the inorganic fine particles and the refractive index of the resin used for the resin particles. As the refractive index, viscosity and temperature of the dispersion solvent, the numerical values contained in the control software are selected. In the case of a mixed solvent, the weight average of the dispersion medium to be mixed is taken.

[0498] <Method for measuring the exposed volume and number of particles from the surface layer>

[0499] The photosensitive drum 1 of the present invention was cut into 5 mm square samples at three locations 50 mm from each longitudinal end and four locations every 90 degrees in the circumferential direction, a total of 12 locations. The photosensitive layer of the sample was coated with platinum for 30 seconds using a vapor deposition device.

[0500] In FIB-SEM (NVision40, manufactured by Carl Zeiss), the following cutting was performed on each sample.

[0501] Beam type: Gallium ion beam

[0502] Accelerating voltage: 1 kV

[0503] Dimensions: Length: 3μm, Width: 3μm, Depth: 3μm

[0504] Processing step: 10nm

[0505] Number of steps: 300

[0506] Furthermore, in each step, SEM observation was performed at an acceleration voltage of 5 kV, a focal length WD of 5 mm, and a field of view of 30,000 times.

[0507] All images captured using the FIB-SEM were converted into three-dimensional images using image processing and analysis software ("ExfactVR 2.1," manufactured by Japan Visual Science Co., Ltd.) via an interface. The number of particles exposed from the surface layer 32 of the photosensitive drum 1 was measured from the three-dimensional image, and the ratio of the number of exposed particles to the total number of particles contained in the surface layer 32 was calculated. Furthermore, the derived three-dimensional image was compared with an image of particles exposed from the surface layer 32 of the photosensitive drum 1 cut using the FIB-SEM. A cross-sectional image of the particle cut at the center of gravity was input via an interface to an image processing and analysis device ("LUZEX AP," manufactured by Nireco Corporation), and the particles in the cross-sectional image were binarized.

[0508] like Figure 11 As shown in the conceptual diagram of FIG, with the surface layer 32 as a cross section, the particle 31 exposed from the surface layer 32 is approximated as a spherical particle of a virtual true sphere, wherein 1 / 4 of the sum of the major axis L and the minor axis l of the particle is set as the radius R of the particle. The center of gravity of the cross section of the particle 31 exposed from the surface layer 32 coincides with the center of gravity of the spherical particle of the virtual true sphere. For the particle 31 exposed from the surface layer 32, the surface layer 32 exposed by the resin portion has substantially no undulations and is calculated by approximating it to a smooth surface. The depth of the portion where the particle 31 contained in the surface layer 32 of the photosensitive drum 1 of the present invention is embedded from the surface layer 32 of the resin portion is defined as h.

[0509] In addition, when the bottom surface of the portion exposed from the surface layer 32 of the resin portion is viewed from above, the virtual true sphere is approximated by a circle having a particle radius C ( Figure 11 is a concept map).

[0510] The volume V1 of the particle is calculated using the following formula (a) based on the volume formula of a sphere.

[0511] V1=4πR 3 / 3…Formula (a)

[0512] The volume V2 of the embedded portion of the particle is calculated using the following formula (b) based on the spherical cap volume formula.

[0513] V2=πh(3C 2 +h 2 ) / 6…Formula (b)

[0514] By taking the difference between V1 and V2, the volume V3 of the exposed portion of the particle is calculated by the following formula (c).

[0515] V3=V2-V3=4πR 3 / 3-πh(3C 2 +h 2 ) / 6…Formula (c)

[0516] For particles existing in the three-dimensional image, V1, V2, and V3 are calculated, and the proportion of the volume of the exposed portion of the particles partially exposed from the surface layer 32 is calculated by dividing the sum of V3 of all existing particles by the sum of V1 of all particles.

[0517] <Method for measuring the coverage and coefficient of variation of particles in the surface layer>

[0518] In the photosensitive drum 1 according to the present invention, when the surface layer 32 is viewed from above, S1 / (S1+S2) can be calculated as follows, where S1 is the total area of the exposed portions of the particles.

[0519] Regarding the particles in the surface layer 32, a 30,000x photographic image of the surface layer 32 of the photosensitive drum 1, taken using a scanning electron microscope (SEM) ("S-4800" manufactured by JEOL Ltd.), was obtained using a scanner. The particles in the photographic image were binarized using an image processing and analysis device ("LUZEX AP" manufactured by Nireco). The area of the exposed portion of the particles on the photosensitive drum 1 in one field of view was defined as S1, and the total area of the particles excluding the exposed portion was defined as S2. The coverage ratio S1 / (S1+S2) (%) was calculated. This coverage ratio was calculated for a total of 10 fields of view, and the average of the obtained coverage ratios was taken as the coverage ratio of the particles in the surface layer 32 of the photosensitive member.

[0520] <Method for measuring Young's modulus of exposed particles in the surface layer>

[0521] As the evaluation machine, an SPM probe station ("NanoNaviReal" manufactured by Hitachi High-Technologies Corporation) equipped with a scanning probe microscope ("S-image" manufactured by Hitachi High-Technologies Corporation) with a built-in heater was used. Before measurement, the evaluation machine was calibrated under the conditions of an allowable range of 2.920±0.119 GPa (Young's modulus) using PMMA (polymethyl methacrylate) particles as a standard substance. The Young's modulus of PMMA measured by the calibrated evaluation machine was 3.01 GPa.

[0522] The particles in the surface layer 32 are measured by SPM, and the average of 10 measurement results is taken as the Young's modulus of the particle for each particle. In addition, the average of the Young's moduli of the 10 particles is defined as the Young's modulus of the exposed particles in the surface layer 32 of the photosensitive member of the present invention.

[0523] <Measurement of Film Thickness of Each Layer>

[0524] The film thickness of each layer of the photosensitive drum 1 except the charge generating layer was obtained by a method using an eddy current film thickness meter (Fischerscope, manufactured by Fischer Instruments) or by a method of converting the specific gravity from the mass per unit area. The film thickness of the charge generating layer was measured by converting the density value of the photosensitive member using a calibration curve obtained in advance from the density value measured by pressing a spectrodensitometer (trade name: X-Rite 504 / 508, manufactured by X-Rite) against the surface of the photosensitive member and the film thickness measurement value obtained by cross-sectional SEM image observation.

[0525] [Example]

[0526] (Manufacturing of photosensitive drums)

[0527] Next, a manufacturing example of the photosensitive drum 1 of the present invention will be described in detail.

[0528] Table 7 shows the type, manufacturer, number average particle diameter, volume average particle diameter, and (volume average particle diameter) / (number average particle diameter) of the particles contained in the surface layer 32 of the photosensitive drum 1 .

[0529] Table 7. Details of particles contained in the surface layer [Table 7]

[0530]

[0531] <Preparation of Surface-treated Particles 1>

[0532] -Methanol: 10 parts by mass

[0533] - Granules 1 (as shown in Table 7): 5 parts by mass

[0534] These were added and dispersed at room temperature for 30 minutes using a US homogenizer. Next, 0.25 parts by mass of n-propyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 10 parts by mass of toluene were added as a reactive surface treatment agent, and the mixture was stirred at room temperature for 60 minutes. The solvent was removed using an evaporator, and the resulting product was heated at 140°C for 60 minutes to prepare surface-treated particles 1 that had been surface-treated with a reactive surface treatment agent. The volume average particle diameter was 136 nm, and the number average particle diameter was 124 nm.

[0535] <Preparation Example of Electrophotographic Photosensitive Member 1>

[0536] [Preparation of Support]

[0537] An aluminum cylinder (JIS-A3003, aluminum alloy) having a diameter of 20 mm and a length of 257.5 mm was used as a support (conductive support).

[0538] [Preparation Example of Conductive Layer Coating Liquid 1]

[0539] -Anatase titanium dioxide

[0540] (average primary particle size 150 nm, niobium content 0.20 wt%): 100 parts by mass

[0541] -Pure water: 1000 parts by mass

[0542] These were dispersed to obtain 1 L of a water suspension, and the water suspension was heated to 60°C.

[0543] A niobium solution obtained by dissolving 3 parts by mass of niobium pentachloride (NbCl5) in 100 mL of 11.4 mol / L hydrochloric acid, a titanic acid solution obtained by mixing 600 mL of a titanium sulfate solution containing 33.7 parts by mass of Ti, and a 10.7 mol / L sodium hydroxide solution were simultaneously added dropwise over 3 hours until the pH of the suspension reached 2 to 3. After the addition was completed, the suspension was filtered, washed, and dried at 110°C for 8 hours.

[0544] The dried product was heat-treated at 800° C. for 1 hour in an air atmosphere to obtain a powder of metal oxide particles 1 having a core material containing titanium oxide and a coating layer containing titanium oxide doped with niobium.

[0545] Next,

[0546] -Phenolic resin

[0547] (Trade name: Plyophen J-325, manufactured by DIC Corporation, resin solid content: 60%, density after curing: 1.3g / cm 2 ): 50 parts by mass

[0548] -1-Methoxy-2-propanol: 35 parts by mass

[0549] -Metal oxide particles 1: 75 parts by mass

[0550] - Glass beads (average particle size: 1.0 mm): 120 parts by mass

[0551] They were mixed, and the resulting mixture was placed in a vertical sand mill and subjected to a dispersion treatment for 4 hours under the conditions of a dispersion temperature of 23±3° C. and a rotation speed of 1500 rpm (circumferential speed: 5.5 m / s) to obtain a metal oxide particle dispersion 1. The glass beads were removed from the metal oxide particle dispersion 1 with a sieve, and

[0552] - Silicone oil (trade name: SH28 coating additive, manufactured by Dow Corning Toray Co., Ltd.): 0.01 parts by mass

[0553] - Silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials, average particle size: 2 μm, density: 1.3 g / cm 2 ): 10 parts by mass

[0554] These were added, and the resulting mixture was stirred and pressure filtered using PTFE filter paper (trade name: PF060, Advantec Toyo Kaisha, Ltd.) to prepare a conductive layer coating liquid 1.

[0555] [Preparation Example of Conductive Layer 1]

[0556] The conductive layer coating liquid 1 was dip-coated on the support and heated at 140° C. for 1 hour to form a conductive layer 1 having a film thickness of 20 μm.

[0557] [Preparation Example of Undercoat Layer Coating Liquid 1]

[0558] - Rutile titanium oxide particles (average primary particle size: 50 nm, manufactured by Tayca): 100 parts by mass

[0559] - Phenolic resin (trade name: Plyophen J-325, manufactured by DIC Corporation, resin solid content: 60% by mass): 132 parts by mass

[0560] -Toluene: 500 parts by mass

[0561] - Vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.): 5 parts by mass

[0562] - Glass beads (0.8 mm diameter): 450 parts by mass

[0563] These were mixed and stirred for 8 hours. Thereafter, toluene was distilled off by reduced pressure distillation, and the mixture was dried at 120° C. for 3 hours to obtain rutile titanium oxide particles 1 surface-treated with vinyltrimethoxysilane.

[0564] -Surface-treated rutile titanium oxide particles: 18 parts by mass

[0565] - N-methoxymethylated nylon (trade name: TORESIN EF-30T, manufactured by Nagase ChemteX Co., Ltd.): 4.5 parts by mass

[0566] - Copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Ltd.): 1.5 parts by mass

[0567] -Methanol: 90 parts by mass

[0568] -1-Butanol: 60 parts by mass

[0569] -Acetone: 15 parts by mass

[0570] - Glass beads (average particle size: 1.0 mm): 120 parts by mass

[0571] These were mixed, and the mixture was subjected to a dispersion treatment with a vertical sand mill for 5 hours to prepare an undercoat layer coating liquid 1.

[0572] [Preparation Example of Undercoat Layer 1]

[0573] The undercoat layer coating liquid 1 was dip-coated on the conductive layer 1 and heated at 170° C. for 30 minutes to form an undercoat layer 1 having a film thickness of 1.0 μm.

[0574] [Preparation Example of Charge Generation Layer 1]

[0575] - Hydroxygallium phthalocyanine (peaks were observed at 7.5° and 28.4° in a graph obtained by CuKα characteristic X-ray diffraction): 10 parts by mass

[0576] - Polyvinyl butyral resin (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.): 5 parts by mass

[0577] -Cyclohexanone: 200 parts by mass

[0578] -Glass beads: 200 parts by mass

[0579] These were dispersed using a sand mill for 6 hours. 150 parts by mass of cyclohexanone and 350 parts by mass of ethyl acetate were added thereto and diluted to obtain a charge generation layer coating solution 1. The obtained charge generation layer coating solution 1 was dip-coated on the undercoat layer 1 and dried at 95°C for 10 minutes to form a charge generation layer 1 having a film thickness of 0.20 μm.

[0580] [Preparation Example of Charge Transport Layer 1]

[0581] Next, prepare the following materials.

[0582] - Charge transport material (hole transport material) represented by structural formula (1-1): 5 parts by mass

[0583] - Charge transport material (hole transport material) represented by structural formula (1-3): 5 parts by mass

[0584] - Polycarbonate (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation): 10 parts by mass

[0585] - 0.02 parts by mass of a polycarbonate resin having copolymerized units of the following structural formula (C-1) and the following structural formula (C-2) (x / y = 0.95 / 0.05: viscosity average molecular weight = 20,000)

[0586] These substances were dissolved in a mixed solvent of 60 parts by mass of toluene / 3 parts by mass of methyl benzoate / 15 parts by mass of tetrahydrofuran to prepare a charge transport layer coating liquid 1. This charge transport layer coating liquid 1 was dip-coated on the charge generating layer 1 to form a coating film, and the coating film was dried at a drying temperature of 40° C. for 5 minutes to form a charge transport layer 1 having a film thickness of 15 μm.

[0587] [Chemical Formula 6]

[0588]

[0589] [Preparation Example 1 of Particle-Containing Surface Layer]

[0590] Next, prepare the following materials.

[0591] - Granules 1 (described in Table 7): 1.2 parts by mass

[0592] -Silicone-modified acrylic compound (trade name: SYMAC US270, manufactured by Toagosei Co., Ltd.): 0.1 parts by mass

[0593] - Cyclohexane: 30 parts by mass

[0594] -1-Propanol: 70 parts by mass

[0595] These were mixed and stirred to prepare a surface layer coating liquid 1.

[0596] This surface layer coating liquid was dip-coated on the charge transport layer 1 to form a coating film, and the resulting coating film was dried at 100° C. for 20 minutes to obtain an electrophotographic photosensitive member 1. The film thickness [μm] of the charge transport layer of the electrophotographic photosensitive member 1, the volume average particle diameter [nm] of the particles contained in the surface layer 32, the number ratio [number %] of the particles exposed from the surface layer 32, the volume ratio [volume %] of the particles exposed from the surface layer 32, the coverage S1 / (S1+S2) and the coefficient of variation caused by the particles exposed from the surface layer 32, and the Young's modulus [GPa] of the surface of the particles exposed from the surface layer 32 were measured. The results are shown in Table 9.

[0597] <Manufacturing Examples of Electrophotographic Photosensitive Members 2 to 34>

[0598] Electrophotographic photosensitive members 2 to 34 were produced in the same manner as in the electrophotographic photosensitive member 1, except that the temperature at which the charge transport layer coating liquid 1 was dip-coated on the charge generating layer 1 to form a coating film and then dried in the charge transport layer 1 preparation example, the kind and addition amount of the particles contained in the surface layer 32, and the addition amounts of cyclohexane and 1-propanol were changed in the electrophotographic photosensitive member 1 production example as shown in Table 8. The physical properties measured in the electrophotographic photosensitive members 2 to 34 are shown in Table 9.

[0599] Table 8. Formulation details of electrophotographic photosensitive members 1 to 34 [Table 8]

[0600]

[0601]

[0602] In Table 8, “EP No.” means “electrophotographic photosensitive member number.” “Addition amount” under “particles” means “addition amount (parts by mass).” “Temperature” means “drying temperature.” “ST particles” means “surface-treated particles.”

[0603] Table 9. Physical properties of electrophotographic photosensitive members 1 to 34 [Table 9]

[0604]

[0605] In Table 9, “EP No.” means “electrophotographic photosensitive member number”. “Film thickness [μm]” means “film thickness of the charge transport layer”. “Volume average particle size [nm]” means “volume average particle size of the particles contained in the surface layer”. “Number ratio [number %]” means “number ratio [number %] of particles exposed from the surface layer”. “Volume ratio [volume %]” means “volume ratio [volume %] of particles exposed from the surface layer”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of the particle surface”.

[0606] <Manufacturing Example of Electrophotographic Photosensitive Member 35>

[0607] Preparation was performed in a similar manner to the Preparation Example of the Charge Transport Layer 1, except that in the Preparation Example of the Electrophotographic Photosensitive Member 1, the charge transport layer coating liquid 35 was dip-coated on the charge generating layer 35 to form a coating film and the coating film was dried at a drying temperature of 120°C for 5 minutes to produce a charge transport layer 35 having a film thickness of 15 μm.

[0608] [Preparation Example 2 of Particle-Containing Surface Layer]

[0609] Next, prepare the following materials.

[0610] - Granules 1 (described in Table 7): 1.2 parts by mass

[0611] - Charge transport material (hole transport material) represented by structural formula (2-1): 0.1 parts by mass

[0612] - Charge transport material (hole transport material) represented by structural formula (3-1): 0.2 parts by mass

[0613] -Silicone-modified acrylic compound (trade name: SYMAC US270, manufactured by Toagosei Co., Ltd.): 0.1 parts by mass

[0614] - Cyclohexane: 30 parts by mass

[0615] -1-Propanol: 70 parts by mass

[0616] These were mixed and stirred to prepare a surface layer coating liquid 2.

[0617] The surface layer coating liquid 2 was dip-coated on the charge transporting layer 1 to form a coating film, and the resulting coating film was dried at 40° C. for 5 minutes.

[0618] After that, under a nitrogen atmosphere, under the conditions of an accelerating voltage of 70kV and an electron beam current of 5.0mA, the coating film was irradiated with an electron beam for 1.6 seconds while rotating the support (irradiated body) at a speed of 300rpm. The dose at the outermost surface layer position was 15kGy. After that, the temperature was raised from 25°C to 100°C in a nitrogen atmosphere for 20 seconds to perform the first heating, thereby forming a surface layer 32 with a film thickness of 1.0μm. The oxygen concentration from electron beam irradiation to subsequent heat treatment was below 10ppm. Next, the coating film was naturally cooled in air until the temperature of the coating film reached 25°C, and a second heat treatment of 20 minutes was performed under the condition that the coating film temperature was 100°C. In this way, an electrophotographic photosensitive member 37 was manufactured. The film thickness [μm] of the charge transport layer of the electrophotographic photosensitive member 37, the film thickness [μm] of the surface layer 32, the volume average particle diameter [nm] of the particles contained in the surface layer 32, the number ratio [number %] of the particles exposed from the surface layer 32, the volume ratio [volume %] of the particles exposed from the surface layer 32, the coverage S1 / (S1+S2) caused by the particles exposed from the surface layer 32, and the Young's modulus [nm] of the surface of the particles exposed from the surface layer 32 were measured. The results are shown in Table 11.

[0619] <Production Examples 36-68 of Electrophotographic Photosensitive Members>

[0620] Electrophotographic photosensitive members 36 to 68 were prepared in the same manner as in the electrophotographic photosensitive member 35, except that the temperature at which the charge transport layer coating liquid 35 was dip-coated onto the charge generating layer 35 to form a coating film and then dried in the preparation example of the charge transport layer 35, the kind and addition amount of the particles contained in the surface layer 32 in the preparation example 2 of the particle-containing surface layer 32, and the addition amounts of cyclohexane and 1-propanol were changed as shown in Table 10. The physical properties measured in the electrophotographic photosensitive members 36 to 68 are shown in Table 11.

[0621] Table 10. Formulation details of electrophotographic photosensitive members 35-68 [Table 10]

[0622]

[0623]

[0624] In Table 10, “EP No.” means “electrophotographic photosensitive member number.” “Addition amount” under “particles” means “addition amount (parts by mass).” “Temperature” means “drying temperature.” “ST particles” means “surface-treated particles.”

[0625] Table 11. Physical properties of electrophotographic photosensitive members 35-68 [Table 11]

[0626]

[0627] In Table 11, “EP No.” means “electrophotographic photosensitive member number”. “Film thickness A [μm]” means “film thickness of charge transport layer”. “Film thickness B [μm]” means “film thickness of surface layer”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio [number %] of particles exposed from the surface layer”. “Volume ratio [volume %]” means “volume ratio [volume %] of particles exposed from the surface layer”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”.

[0628] <Production Examples 69-82 of Electrophotographic Photosensitive Members>

[0629] Electrophotographic photosensitive members 69 to 82 were prepared in the same manner as in the electrophotographic photosensitive member 1, except that the temperature at which the charge transport layer coating liquid 1 was dip-coated onto the charge generating layer 1 to form a coating film and then dried in the charge transport layer 1 preparation example, the kind and addition amount of the particles contained in the surface layer 32, and the addition amounts of cyclohexane and 1-propanol in the charge transport layer 1 preparation example were changed as shown in Table 12. The physical properties measured in the electrophotographic photosensitive members 69 to 82 are shown in Table 13.

[0630] Table 12. Formulation details of electrophotographic photosensitive members 69-82

[0631]

[0632] In Table 12, “EP No.” means “electrophotographic photosensitive member number.” “Addition amount” under “particles” means “addition amount (parts by mass).” “Temperature” means “drying temperature.” “ST particles” means “surface-treated particles.”

[0633] Table 13. Physical properties of electrophotographic photosensitive members 69 to 82 [Table 13]

[0634]

[0635] In Table 13, “EP No.” means “electrophotographic photosensitive member number”. “Film thickness [μm]” means “film thickness of charge transport layer”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio [number %] of particles exposed from the surface layer”. “Volume ratio [volume %]” means “volume ratio [volume %] of particles exposed from the surface layer”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”.

[0636] <Production Examples 83-96 of Electrophotographic Photosensitive Members>

[0637] Electrophotographic photosensitive members 83 to 96 were prepared in the same manner as in the electrophotographic photosensitive member 35, except that the temperature at which the charge transport layer coating liquid 37 was dip-coated onto the charge generating layer 37 to form a coating film and then dried in the preparation example of the electrophotographic photosensitive member 35, the kind and addition amount of the particles contained in the surface layer 32 in the preparation example 2 of the particle-containing surface layer 32, and the addition amounts of cyclohexane and 1-propanol were changed as shown in Table 14. The physical properties measured in the electrophotographic photosensitive members 83 to 96 are shown in Table 15.

[0638] <Production Example 97 of Electrophotographic Photosensitive Member>

[0639] Electrophotographic photosensitive member 24 was prepared in the same manner as in Electrophotographic photosensitive member 1, except that the drying temperature and drying time in Charge Transport Layer 1 Preparation Example 1 in Electrophotographic Photosensitive Member 1 Production Example 1 were changed to 130° C. and 20 minutes. The physical properties measured in Electrophotographic Photosensitive Member 97 are shown in Table 15.

[0640] <Production Example 98 of Electrophotographic Photosensitive Member>

[0641] Electrophotographic photosensitive member 98 was prepared in the same manner as in electrophotographic photosensitive member 35 except that particles 1 were not added in [Preparation Example 2 of particle-containing surface layer] in preparation example of electrophotographic photosensitive member 35. Physical properties measured in electrophotographic photosensitive member 98 are shown in Table 15.

[0642] Table 14. Formulation details of electrophotographic photosensitive members 83-98 [Table 14]

[0643]

[0644] In Table 14, “EP No.” means “electrophotographic photosensitive member number.” “Addition amount” under “particles” means “addition amount (parts by mass).” “Temperature” means “drying temperature.” “ST particles” means “surface-treated particles.”

[0645] Table 15. Physical properties of electrophotographic photosensitive members 83-98 [Table 15]

[0646]

[0647] In Table 15, “EP No.” means “electrophotographic photosensitive member number”. “Film thickness A [μm]” means “film thickness of charge transport layer”. “Film thickness B [μm]” means “film thickness of surface layer”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio [number %] of particles exposed from the surface layer”. “Volume ratio [volume %]” means “volume ratio [volume %] of particles exposed from the surface layer”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”.

[0648] (Structure of Imaging Apparatus)

[0649] exist Figure 9In the imaging apparatus shown in , imaging apparatus 1, imaging apparatus 2, and imaging apparatus 3 are prepared, each having rollers with different longitudinal widths for stretching intermediate transfer belt 8. The longitudinal widths of the various components and rollers are shown in Table 16. Since the imaging apparatus of this embodiment is compatible with standard-size paper, images can be formed on paper up to 216 mm wide, and the longitudinal width of the primary transfer roller 6 in each of imaging apparatus 1, imaging apparatus 2, and imaging apparatus 3 is 216 mm or greater. Similarly, since secondary transfer must also be reliably performed relative to the paper width in the opposing roller 28, the longitudinal width is set to 216 mm or greater in each of imaging apparatus 1, imaging apparatus 2, and imaging apparatus 3. The width of the tension roller 10 is also close to the width of the intermediate transfer belt, so that the belt can be stably stretched and tensioned across the entire belt width.

[0650] On the other hand, as the width of the drive roller 9 relative to the intermediate transfer belt 8 decreases, when the belt deflects in the longitudinal direction, the deflection force acts in the direction of restoring the deflection, which is conducive to belt damage. Therefore, the drive roller 9 has the smallest longitudinal width among the three tensioning rollers.

[0651] In the image forming apparatus 1, the primary transfer roller width and the minimum width of the roller stretching the intermediate transfer belt 8 have the following relationship:

[0652] The width of the primary transfer roller is less than the minimum width of the tension roller.

[0653] In imaging device 2 and imaging device 3, the following relationship is established:

[0654] The width of the primary transfer roller is greater than the minimum width of the tension roller.

[0655] In the imaging apparatus 2, the minimum width of the tension roller is larger than the image-formable width of 216 mm and equal to the width of the charging roller. In the imaging apparatus 3, the minimum width of the tension roller is set to be smaller than the image-formable width of 216 mm.

[0656] Table 16. Configurations of imaging devices 1 to 3 [Table 16]

[0657]

[0658] (Evaluation method)

[0659] The effect of this example was confirmed under the following conditions. Figure 9 In the image forming apparatus shown, electrophotographic photosensitive members 1 to 98 were attached, and a durability test was performed in which images were actually formed on a large amount of recording materials to examine transfer performance in the initial stage of durability and after durability and the presence or absence of durability problems.

[0660] <Transfer Performance Evaluation Method>

[0661] Under an environment of temperature 25°C and humidity 50%, a black image is formed over the entire area in the process box PK, and the transfer residual toner on the photosensitive drum after passing through the primary transfer nip is taped using a transparent polyester adhesive tape. The adhesive tape is attached to paper, and the density is measured using an X-Rite color reflection densitometer (X-rite 500 series, manufactured by X-rite), and the toner amount of the transfer residual toner is quantitatively ascertained as the concentration. Incidentally, the concentration corresponding to the amount of pure toner is obtained by subtracting the concentration of the toner only attached to the paper with the adhesive tape, and the density measurement is performed uniformly at five positions in the longitudinal width direction to obtain an average value. Based on the concentration of the transfer residual toner, the transfer performance is graded according to the following evaluation criteria.

[0662] [Evaluation criteria]

[0663] A: Transfer residual concentration is less than 0.20

[0664] B: Transfer residual density is 0.20 or more and less than 0.50

[0665] C: Transfer residual density is 0.50 or more and less than 1.0

[0666] D: Transfer residual concentration is 1.0 or more

[0667] <Durability Method>

[0668] Under an environment of 25°C and 50% humidity, 2,000 sheets of text images with a 1% print percentage were fed daily for each color process cartridge, and a continuous sheet durability test was performed up to 50,000 sheets. In the continuous sheet durability test, A4-size GF-C081 (manufactured by Canon Inc.) was used as the recording material. The continuous sheet durability was evaluated by combining the configurations of Image Forming Apparatus 1, Image Forming Apparatus 2, and Image Forming Apparatus 3, and the corresponding photosensitive drum configurations.

[0669] After the durability test, the transfer performance was evaluated in the same manner as in the initial stage, and the durability change in the transfer performance was examined. In addition, in order to detect image defects due to local damage to the photosensitive drum 1, a black halftone image (toner application amount: 0.2 mg / cm 2 ), and inspected for image uniformity, presence of local defects, etc. In addition, the surface layer 32 of the photosensitive drum 1 was observed at a magnification of 30,000 times using a scanning electron microscope (SEM) ("S-4800", manufactured by JEOL Ltd.), and inspected for the presence of local damage such as convex shapes or holes caused by particle detachment.

[0670] [Evaluation criteria]

[0671] A: No halftone image defects, no photosensitive drum defects

[0672] B: No halftone image defects, convex changes occur

[0673] C: No halftone image defects, holes due to particle detachment

[0674] D: There are halftone image defects

[0675] (Evaluation Results)

[0676] Tables 11 to 14 show the relationship between the evaluation results of initial transferability, transferability after endurance, and damage of the photosensitive drum 1 after endurance and the physical properties of the photosensitive drum when the electrophotographic photosensitive members 1 to 98 were combined with the image forming apparatuses 1 to 3 for endurance.

[0677] <Improvement of Transfer Performance by Particle-Containing Effects>

[0678] In the particle-free electrophotographic photosensitive members 97 and 98, the transfer residue was grade D even in the initial stage; while in the other electrophotographic photosensitive members, there were grade differences due to the formulation of the photosensitive drum 1 and the physical properties of the obtained surface, but in the electrophotographic photosensitive members 1 to 68, the effect of improving the transfer residue to grade C or above was obtained in the initial stage and after durability.

[0679] <Improvement of Transfer Performance by Volume Average Particle Size Effect>

[0680] In the electrophotographic photosensitive members 69 and 83 using the particles 3 having a large particle diameter and a volume average particle diameter of 550 nm, the transfer residue was rank D even in the initial stage, and the transferability was not improved.

[0681] In the electrophotographic photosensitive members 70 and 84 using the particles 4 having a small particle size and a volume average particle size of 37 nm, the transfer residue was rank D even in the initial stage, and the transferability was not improved.

[0682] In the electrophotographic photosensitive members 1 to 68 using particles 1, 2, 5, and 6 and surface-treated particle 1, the effect of improving transfer performance was confirmed, and it was confirmed that the volume average particle diameter range other than 37 nm or less and 550 nm or more is suitable for improving transfer performance. More preferably, the volume average particle diameter is at least 50 nm and not more than 350 nm.

[0683] <Achieving both transfer performance and durability by the volume ratio of exposed particles>

[0684] Regarding the ratio of the exposed particle volume to the volume of the particles contained in the surface layer 32, in the electrophotographic photosensitive members 69, 76, 78, 80, 82, 83, 90, 92, 94 and 96 in which the exposure ratio was low and less than 30 volume %, the transfer residue was grade D even in the initial stage, and the transferability was not improved.

[0685] On the other hand, in the electrophotographic photosensitive members 71, 73, 74, 75, 77, 79, 81, 85, 87, 88, 89, 91, 93, and 95 having a high exposure ratio exceeding 80 volume %, the transferability after durability was rank D, and the durability was problematic.

[0686] Therefore, in the range of 80% by number or more of the ratio of the number of exposed particles to the number of all particles in the surface layer confirmed in this example, it was confirmed that the range of 30 to 80% by volume of the ratio of the volume of exposed particles to the volume of all particles is appropriate from the viewpoint of improving both transferability and durability performance.

[0687] <Improvement of Transfer Performance by Particle Coverage S1 / (S1+S2)>

[0688] In the electrophotographic photosensitive members 22, 23, 56, and 57 in which the particle coverage ratio S1 / (S1+S2) in the surface layer was low and lower than 0.13, the transfer residue was rank C even in the initial stage, and the effect of improving transferability was not significant.

[0689] On the other hand, in the electrophotographic photosensitive members 30 and 64 having a high coverage ratio S1 / (S1+S2) of 0.85, the initial transfer residue was also rank C, and the effect of improving transferability was not significant.

[0690] Therefore, it was confirmed that the particle coverage ratio S1 / (S1+S2) in the surface layer is more preferably in a range other than 0.13 or less and 0.85 or more in the following formula (A).

[0691] 0.13<S1 / (S1+S2)<0.85…Formula (A)

[0692] More preferably, the following formula (B) is satisfied.

[0693] 0.15≤S1 / (S1+S2)≤0.80…Formula (B)

[0694] <Achieving both transfer performance and durability through coverage coefficient of variation>

[0695] In the electrophotographic photosensitive members 18, 19, 31, 52, 53, and 65, in which the coefficient of variation of the coverage ratio of the particles contained in the surface layer 32 was high and was 27% or more, the transfer residue at the initial stage or after the durability test was rank C, and the effect of improving the transferability during the entire durability test was not significant. Therefore, it was confirmed that the coefficient of variation of the coverage ratio of the particles contained in the surface layer 32 is more preferably less than 26%.

[0696] Improving transfer performance through particle surface Young's modulus

[0697] In the electrophotographic photosensitive members 34 and 68 using Particle 7, transfer residue was ranked C even in the initial stage, and the effect of improving transferability was not significant. This is believed to be because the Young's modulus of the exposed particle surface was 0.5 GPa, which was lower than that of the electrophotographic photosensitive members of other examples, and the effect of reducing the contact area with the toner was limited. Therefore, it was confirmed that the Young's modulus of the particle surface is more preferably greater than 0.5 GPa.

[0698] Maintaining durability through the structure of imaging equipment

[0699] In the configuration of the image forming apparatus 1 , although some variation in convexity was observed in the electrophotographic photosensitive members 1 to 68 , no image defect was generated, and appropriate image quality could be obtained even after durability.

[0700] On the other hand, in the electrophotographic photosensitive members 70, 71, 73, 74, 75, 77, 79, 81, 84, 85, 87, 88, 89, 91, 93, and 95 in which the exposure ratio was high and exceeded 80 volume %, a state in which particles were detached after durability was observed.

[0701] In addition, in the electronic photographic photosensitive members 7, 8, 17, 19, 21, 41, 42, 51, 53 and 55 in which image defects did not occur but the exposure ratio was high and was 70 volume % or more, convex deformation was observed, and it was confirmed that from the viewpoint of durability, image quality and damage on the photosensitive drum surface, the exposure volume ratio relative to the total particle volume was 80 volume % or less, more preferably 70 volume % or less.

[0702] In addition, in the configuration of the imaging device 2, a state of particle detachment was observed in the electrophotographic photosensitive members 70, 71, 73, 74, 75, 77, 79, 81, 84, 85, 87, 88, 89, 91, 93 and 95 having a high exposure volume ratio and the electrophotographic photosensitive members 7, 8, 17, 19, 21, 41, 42, 51, 53 and 55.

[0703] The damaged portion was the end portion of the charging roller 2 and the driving roller 9, which was 115 mm from the longitudinal center, and peeling was obvious at this portion.

[0704] In the configuration of the imaging device 3, image defects due to vertical stripe-like density unevenness occur in the electronic photographic photosensitive members 70, 71, 73, 74, 75, 77, 79, 81, 84, 85, 87, 88, 89, 91, 93 and 95 having a high exposure volume ratio, and the electronic photographic photosensitive members 7, 8, 17, 19, 21, 41, 42, 51, 53 and 55.

[0705] The image defect occurred at the end of the drive roller 9, 103 mm from the longitudinal center, and peeling was noticeable even on the photosensitive drum surface. Vertical streaky density unevenness is believed to be the cause of image density unevenness, which is due to localized deterioration in transfer performance caused by particle peeling at the position corresponding to the end of the drive roller 9.

[0706] Figure 12 、 Figure 13 and Figure 14 1 and 2 are conceptual diagrams illustrating stretched and deformed states of the intermediate transfer belt 8 in (A) image forming apparatus 1 , (B) image forming apparatus 2 , and (C) image forming apparatus 3 . Figure 12 shows the status of the imaging device 1, Figure 13 shows the status of the imaging device 2, Figure 14 The status of the imaging device 3 is shown. Figure 12 (A-1), Figure 13 (B-1) and Figure 14 (C-1) shows that Figure 9 The intermediate transfer belt 8 is stretched and deformed relative to the opposing roller 28 and the driving roller 9 when viewed from the right side (from the direction of arrow LK1). Since the longitudinal width of the intermediate transfer belt 8 is longer than the longitudinal width of each stretching roller, and as a belt, it is stretched along the tension roller 10, the intermediate transfer belt 8 is stretched and deformed relative to the opposing roller 28 and the driving roller 9. Figure 9 As a result of the leftward pulling, the belt is stretched while being deformed at the end of each stretching roller, as shown in FIG. Figure 12 (A-1), Figure 13 (B-1) and Figure 14 If the intermediate transfer belt 8 is kept in this state for a long time, the intermediate transfer belt 8 contracts, curling occurs in a deformed belt state, and steps are formed due to the curling.

[0707] Figure 12 (A-2), Figure 13 (B-2) and Figure 14 (C-2) shows that Figure 9 The state in which the intermediate transfer belt 8 is wound around the photosensitive drum 1 at the primary transfer nip when viewed from the right side (from the direction of arrow LK2). In each figure, the size relationship of the longitudinal lengths of the primary transfer roller 6, the photosensitive drum 1 and the charging roller 2 can be seen as shown in Table 16.

[0708] exist Figure 12 (A-3), Figure 13 (B-3) and Figure 14 (C-3) is shown in an enlarged manner Figure 12 (A-2), Figure 13 (B-2) and Figure 14 (C-2) shows the end of the primary transfer roller 6. In addition, a cross section of the intermediate transfer belt 8 at the time when the phase of forming a curl at the longitudinal end of the driving roller 9 reaches the primary transfer nip is shown.

[0709] When printing is performed in this state, Figure 12 (A-2), Figure 13 (B-2) and Figure 14 (C-2) and Figure 12 (A-3), Figure 13 (B-3) and Figure 14 As shown in (C-3), the intermediate transfer belt 8 passes through the primary transfer nip in a curled shape. In addition, the curling step is eliminated during the continuous printing operation, but since it takes time for the step to disappear, the intermediate transfer belt 8 repeatedly passes through the primary transfer nip.

[0710] exist Figure 13 (B-2), Figure 14 (C-2), Figure 13 (B-3) and Figure 14 In the configurations of imaging devices 2 and 3 shown in (C-3), a curling step caused by the drive roller 9 exists inside the longitudinal width of the primary transfer roller 6. Consequently, the curling step strongly rubs against the surface of the photosensitive drum 1 as it passes through the primary transfer nip. It is believed that repeated friction due to durability causes particle separation and vertical streaky density unevenness in the surface layer.

[0711] On the other hand, Figure 12 (A-2) and Figure 12 In the configuration of the image forming apparatus 1 shown in (A-3), since the curling step is located outside the primary transfer roller 6, the curling step does not rub the surface of the photosensitive drum 1 when passing through the primary transfer nip.

[0712] As described above, it was confirmed that the configuration in which the transfer member width is smaller than the tension roller width is suitable in the image forming apparatus combinable with the process cartridge using the photosensitive drum 1 containing particles in the surface layer.

[0713] The effect of the present invention can be obtained as long as the width of the transfer member is smaller than the width of at least one of the plurality of tension rollers (driving roller 9, tension roller 10, opposing roller 28, etc.). Figure 13 In the configuration of the image forming apparatus 2 shown in FIG. 1 , the width of the transfer roller 6 is smaller than the width of the opposing roller 28 but larger than the width of the driving roller 9. Even with such a configuration, for example, as shown in Table 17, a higher image quality than that obtained using Figure 14 The images with fewer image defects (Examples 7, 8, 17, 19, and 21) are shown in the case of the image forming apparatus 3. This is considered to be because the relationship of image forming width < driving roller 9 is satisfied in the image forming apparatus 2.

[0714] In addition, Figure 12 In the image forming apparatus 1 shown, the width of the transfer member is smaller than the width of either the driving roller 9 or the opposing roller 28. According to such a configuration, as shown in Table 17, more preferable effects can be obtained (Examples 7, 8, 17, 19, 21).

[0715] In this example, the Figure 9 The system shown does not include a primary transfer residual toner cleaning device, but a primary transfer residual toner cleaning device may also be provided. For example, a so-called blade cleaning system in which a rubber blade contacts the photosensitive drum 1 to collect the primary transfer residual toner can also achieve the effects of the present invention.

[0716] In this example, a metal shaft is used as the primary transfer member. However, as long as the primary transfer nip is formed by bringing the intermediate transfer belt 8 into contact with the photosensitive drum 1, the same effect can be achieved by using other members. Specifically, the effects of the present invention can also be achieved by using a rubber roller, a resin roller, a fiber brush, a pad, or the like as the primary transfer member to push the intermediate transfer belt 8 into contact with the photosensitive drum 1.

[0717] In this example, only the use of Figure 10 (A) and Figure 10 The layer structure of the laminated photosensitive layer shown in (B) is as described above. Figure 10 In the layer structure of the single-layer photosensitive layer shown in (C), it is difficult to control the arrangement of particles, but when the arrangement is controlled within the range defined in the present invention, the same effect can be obtained even in the single-layer photosensitive layer.

[0718] Table 17 to Table 20. Evaluation results of image forming apparatus using photosensitive drum 1

[0719] [Table 17]

[0720]

[0721] In Table 17, “EP No.” means “electrophotographic photosensitive member number”. “Damage” means “image defect after durability, convex damage”. “IF 1” to “IF 3” mean “imaging device 1” to “imaging device 3”. “Physical properties” means “photosensitive drum physical properties”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio of particles exposed from the surface layer [number %]”. “Volume ratio [volume %]” means “volume ratio of particles exposed from the surface layer [volume %]”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”.

[0722] [Table 18]

[0723]

[0724] In Table 18, “EP No.” means “electrophotographic photosensitive member number”. “Damage” means “image defect after durability, convex damage”. “IF 1” to “IF 3” mean “imaging device 1” to “imaging device 3”. “Physical properties” means “photosensitive drum physical properties”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio of particles exposed from the surface layer [number %]”. “Volume ratio [volume %]” means “volume ratio of particles exposed from the surface layer [volume %]”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”.

[0725] [Table 19]

[0726]

[0727] In Table 19, “EP No.” means “electrophotographic photosensitive member number”. “Damage” means “image defect after durability, convex damage”. “IF 1” to “IF 3” mean “imaging device 1” to “imaging device 3”. “Physical properties” means “photosensitive drum physical properties”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio of particles exposed from the surface layer [number %]”. “Volume ratio [volume %]” means “volume ratio of particles exposed from the surface layer [volume %]”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”. “N / M” means “not measured”.

[0728] [Table 20]

[0729]

[0730] In Table 20, “EP No.” means “electrophotographic photosensitive member number”. “Damage” means “image defect after durability, convex damage”. “IF 1” to “IF 3” mean “imaging device 1” to “imaging device 3”. “Physical properties” means “photosensitive drum physical properties”. “Volume average particle size [nm]” means “volume average particle size of particles contained in the surface layer”. “Number ratio [number %]” means “number ratio of particles exposed from the surface layer [number %]”. “Volume ratio [volume %]” means “volume ratio of particles exposed from the surface layer [volume %]”. “S1 / (S1+S2)” means “coverage S1 / (S1+S2) caused by particles”. “Variation coefficient [%]” means “variation coefficient of coverage caused by particles”. “Young’s modulus [GPa]” means “Young’s modulus of particle surface”. “N / M” means “not measured”.

[0731] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded as broad a scope as possible so as to encompass all modifications and equivalent structures and functions.

[0732] This application claims the benefit of Japanese Patent Application No. 2022-197144, filed December 9, 2022, and Japanese Patent Application No. 2022-197127, filed December 9, 2022, the entire disclosures of which are incorporated herein by reference.

[0733] [Reference Signs List]

[0734] 1 Electrophotographic photosensitive member

[0735] 8 Intermediate transfer member

[0736] 100 Imaging Equipment

[0737] 105 surface layer

[0738] 106, 107 particles

[0739] 1 Image drum

[0740] 6 Primary transfer roller

[0741] 8 Intermediate transfer belt

[0742] 9 Drive roller

[0743] 10 tension roller

[0744] 28 Opposite roller

[0745] 31 Particles exposed from the surface layer

[0746] P Processing Box

[0747] 101, 201, 301 particles 103.

Claims

1. An imaging device comprising: image carrier; and an intermediate transfer member configured to transfer the toner on the image carrier to a surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material; in: The image carrier has a surface layer containing particles and a binder resin, On the surface of the surface layer, when the area occupied by the particles is represented by S1 and the area occupied excluding the particles is represented by S2, S1 / (S1+S2) is at least 0.70 and not more than 1.00, There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer. Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA, When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc, Satisfies 80nm≦DA≦2×(1 / Spc).

2. The imaging device according to claim 1, wherein When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and The standard deviation of the distance between the centers of gravity of the convex portions is 250 nm or less.

3. An imaging device comprising: image carrier; as well as an intermediate transfer member configured to transfer the toner on the image carrier to a surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material, in: The image carrier has a surface layer containing particles and a binder resin, There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer. Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA, When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and The standard deviation of the distance between the centers of gravity of the convex parts is 250nm or less, and When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc, Satisfies 80nm≦DA≦2×(1 / Spc).

4. The imaging device according to claim 1, wherein In the cross section of the surface layer, when the average film thickness of the surface layer at the portion of the surface layer containing no particles having a particle diameter within the range of DA ± 20 nm is represented by T, Satisfies DA>T.

5. The imaging device according to claim 4, wherein The peak top particle size DB with the smaller peak top particle size value in the comparison between the first peak and the second peak satisfies: DB <T。 6. The imaging device according to claim 5, wherein In the surface layer, Meet DB / DA>1 / 10.

7. The imaging device according to claim 1, wherein Among the number of convex portions present on the surface of the surface layer, The number ratio of the protrusions generated by particles having a particle diameter within the range of DA ± 20 nm is 90% by number or more.

8. The imaging device according to claim 1, wherein The half-value width of the peak having the larger peak top particle diameter value when compared between the first peak and the second peak is 50 nm or less.

9. The imaging device according to claim 1, wherein The roundness of particles with a particle diameter within the range of DA ± 20 nm is 0.950 or greater.

10. The imaging device according to claim 1, wherein forming a groove shape on the surface of the intermediate transfer member in a direction along the moving direction of the intermediate transfer member, and The surface of the intermediate transfer member that faces the image carrier is the surface excluding the groove shape.

11. The imaging device according to claim 1, wherein The intermediate transfer member has a surface layer and a base layer, Here, the surface layer of the intermediate transfer member contains an acrylic resin.

12. The image forming apparatus according to claim 1, comprising means configured to provide a peripheral speed difference between a peripheral speed of the image carrier and a peripheral speed of the intermediate transfer member.

13. The imaging device according to claim 1, wherein The arithmetic mean curvature Spc of peak points in the surface roughness profile of the surface of the intermediate transfer member facing the image carrier is 7,000 [1 / mm] or less.

14. The imaging device according to any one of claims 1 to 13, wherein The ratio of the volume of the particles to the total volume of the surface layer is 40 volume % to 90 volume %.

15. A process cartridge attachable to an image forming apparatus having an intermediate transfer member, the process cartridge comprising: an image carrier having a surface layer containing particles and a binder resin; On the surface of the surface layer, when the area occupied by the particles is represented by S1 and the area occupied excluding the particles is represented by S2, S1 / (S1+S2) is at least 0.70 and not more than 1.00, There are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer. Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA, Satisfy 80nm≤DA, The intermediate transfer member of the image forming apparatus is an intermediate transfer member configured to transfer the toner on the image carrier to the surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to a transfer material; When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc, Satisfies DA≤2×(1 / Spc).

16. The process cartridge according to claim 15, wherein When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and The standard deviation of the distance between the centers of gravity of the convex portions is 250 nm or less.

17. A process cartridge attachable to an image forming apparatus having an intermediate transfer member, the process cartridge comprising: an image carrier having a surface layer containing particles and a binder resin, Among them, there are multiple peaks in the particle size distribution based on the number of particles contained in the surface layer. Among the plurality of peaks, among the peaks having a particle diameter of 20 nm or more at the peak top in the particle size distribution, the peak having the largest peak top frequency is defined as the first peak, and the peak having the second largest peak top frequency is defined as the second peak, and When the peak top particle diameter having a larger peak top particle diameter value in comparison between the first peak and the second peak is represented by DA, Satisfy 80nm≤DA, When the surface layer is observed from above, the average value of the distance between the centers of gravity of the convex portions generated by particles having a particle diameter within the range of DA ± 20 nm is at least 150 nm and not more than 500 nm, and The standard deviation of the distance between the centers of gravity of the convex parts is 250nm or less, and The intermediate transfer member of the image forming apparatus is an intermediate transfer member configured to transfer the toner on the image carrier to the surface of the intermediate transfer member at a contact portion with the image carrier and to convey the toner to transfer the toner to the transfer material, and When the arithmetic mean curvature of the peak points in the surface roughness shape of the surface of the intermediate transfer member facing the image carrier at the contact portion is represented by Spc, Satisfies DA≤2×(1 / Spc).

18. The process cartridge according to claim 15, wherein In the cross section of the surface layer, when the average film thickness of the surface layer at the portion of the surface layer containing no particles having a particle diameter within the range of DA ± 20 nm is represented by T, Satisfies DA>T.

19. The process cartridge according to claim 18, wherein The peak top particle size DB with the smaller peak top particle size value in the comparison between the first peak and the second peak satisfies: DB <T。 20. The process cartridge according to claim 19, wherein In the surface layer, Meet DB / DA>1 / 10.

21. The process cartridge according to claim 15, wherein Among the number of convex portions present on the surface of the surface layer, The number ratio of the protrusions generated by particles having a particle diameter within the range of DA ± 20 nm is 90% by number or more.

22. A process cartridge according to claim 15, wherein The half-value width of the peak having the larger peak top particle diameter value when compared between the first peak and the second peak is 50 nm or less.

23. A process cartridge according to claim 15, wherein The roundness of particles with a particle diameter within the range of DA ± 20 nm is 0.950 or greater.

24. A process cartridge according to claim 15, wherein In an image forming apparatus to which a process cartridge is attachable, forming a groove shape on the surface of the intermediate transfer member in a direction along the moving direction of the intermediate transfer member, and The surface of the intermediate transfer member that faces the image carrier is the surface excluding the groove shape.

25. The process cartridge according to claim 15, wherein In an image forming apparatus to which a process cartridge is attachable, The intermediate transfer member has a surface layer and a base layer, Here, the surface layer of the intermediate transfer member contains an acrylic resin.

26. A process cartridge according to claim 15, wherein Image forming devices to which process cartridges can be attached include: A device configured to provide a peripheral speed difference between the peripheral speed of the image carrier and the peripheral speed of the intermediate transfer member.

27. A process cartridge according to claim 15, wherein In an image forming apparatus to which a process cartridge is attachable, The arithmetic mean curvature Spc of peak points in the surface roughness profile of the surface of the intermediate transfer member facing the image carrier is 7,000 [1 / mm] or less.

28. The process cartridge according to any one of claims 15 to 27, wherein The ratio of the volume of the particles to the total volume of the surface layer is 40 volume % to 90 volume %.

29. An imaging device comprising: An endless transfer belt is stretched by a plurality of stretching rollers; as well as a transfer member provided on the inner peripheral side of the transfer belt, wherein the process cartridge is attachable to an imaging device, wherein the width of the transfer member in the axial direction of the plurality of tenter rollers is smaller than the width of at least one of the plurality of tenter rollers; The process cartridge has an image bearing member having a surface layer on which a toner image is carried. The image carrier contains particles partially exposed from a surface layer of the image carrier, The volume average particle size of the particles is greater than 37 nm and less than 550 nm. 80% by number or more of the particles contained in the cross section of the surface layer are partially exposed from the surface layer, and the total volume of the exposed portion is at least 30% by volume and not more than 80% by volume relative to the total volume of the contained particles, and In the axial direction, the width of the surface layer of the image carrier is formed in a region wider than the width of the transfer member.

30. The imaging device according to claim 29, wherein The volume average particle size of the particles is at least 50 nm and not more than 350 nm.

31. The imaging device according to claim 29, wherein In the process cartridge, when the surface layer is viewed from above, when the total area of the exposed portion of the particles partially exposed from the surface layer is represented by S1 and the total area of the portion other than the exposed portion of the particles partially exposed from the surface layer is represented by S2, S1 / (S1+S2) satisfies the following formula (A): 0.13<S1 / (S1+S2)<0.85…Formula (A).

32. The imaging device according to claim 31, wherein S1 / (S1+S2) satisfies the following formula (B): 0.15≤S1 / (S1+S2)≤0.80…Formula (B).

33. The imaging device according to claim 31, wherein In the process box, when the surface layer is observed from above, when the total area of the exposed portions of the particles is represented by S1 and the total area of the portion other than the exposed portions of the particles is represented by S2, the coefficient of variation of S1 / (S1+S2) is less than 26%.

34. The imaging device according to claim 29, wherein In the process cartridge, the Young's modulus of the particles is 0.60 GPa or more.

35. The imaging device according to claim 29, wherein The width of the transfer member in the axial direction of the plurality of tension rollers is smaller than the width of any one of the plurality of tension rollers.

36. The imaging device according to claim 29, wherein The transfer belt has a width greater than that of the plurality of tension rollers.

37. The imaging device according to claim 29, wherein In the axial direction of the plurality of tension rollers, an image width of the transfer belt is smaller than a width of a driving roller included in the plurality of tension rollers.

38. A process cartridge attachable to an image forming apparatus having an endless transfer belt stretched by a plurality of stretching rollers and a transfer member provided on an inner peripheral side of the transfer belt, wherein In the image forming apparatus, a width of the transfer member in the axial direction of the plurality of tenter rollers is smaller than a width of at least one of the plurality of tenter rollers, The process cartridge includes an image carrier having a surface layer that carries a toner image. wherein the image carrier has particles partially exposed from a surface layer, The volume average particle size of the particles is greater than 37 nm and less than 550 nm. 80% by number or more of the particles contained in the cross section of the surface layer are partially exposed from the surface layer, and the total volume of the exposed portion is at least 30% by volume and not more than 80% by volume relative to the total volume of the contained particles, and In the axial direction, the width of the surface layer of the image carrier is formed in a region wider than the width of the transfer member.

39. A process cartridge according to claim 38, wherein The volume average particle size of the particles is at least 50 nm and not more than 350 nm.

40. A process cartridge according to claim 38, wherein When the surface layer of the image carrier is observed from above, when the total area of the exposed portions of the particles partially exposed from the surface layer is represented by S1 and the total area of the portion other than the exposed portions of the particles partially exposed from the surface layer is represented by S2, S1 / (S1+S2) satisfies the following formula (A): 0.13<S1 / (S1+S2)<0.85…Formula (A).

41. A process cartridge according to claim 40, wherein S1 / (S1+S2) satisfies the following formula (B): 0.15≤S1 / (S1+S2)≤0.80…Formula (B).

42. A process cartridge according to claim 40, wherein When the surface layer of the image carrier is observed from above, when the total area of the exposed portions of the particles is represented by S1 and the total area of the portion other than the exposed portions of the particles is represented by S2, the coefficient of variation of S1 / (S1+S2) is less than 26%.

43. A process cartridge according to claim 38, wherein The Young's modulus of the particles of the image carrier is 0.60 GPa or more.

44. An image forming apparatus to which a process cartridge according to claim 38 is attachable, wherein: The width of the transfer member in the axial direction of the plurality of tension rollers is smaller than the width of any one of the plurality of tension rollers.

45. An image forming apparatus to which a process cartridge according to claim 38 is attachable, wherein: The transfer belt has a width greater than that of the plurality of tension rollers.

46. An image forming apparatus to which a process cartridge according to claim 38 is attachable, wherein: In the axial direction of the plurality of tension rollers, an image width of the transfer belt is smaller than a width of a driving roller included in the plurality of tension rollers.

Images