Image forming apparatus and process cartridge

Abstract

To provide an image forming apparatus that suppresses the decline in dot reproducibility. [Solution] An image forming apparatus comprising a photoreceptor, a charging device, an electrostatic image forming apparatus, a developing device containing an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and a transfer device, wherein when the silicone oil and silica particles adhering to the surface of the charging member are measured by total internal reflection measurement using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A derived from the Si-C stretching of the silicone oil and the peak intensity B derived from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less.

Description

[Technical Field]

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

[0002] Image formation by electrophotography involves, for example, charging the surface of a photoreceptor, and then forming an electrostatic charge image on this surface according to the image information. Next, this electrostatic charge image is developed with a developer containing toner to form a toner image, and this toner image is transferred and fixed to the surface of a recording medium.

[0003] Here, Patent Documents 1 to 4 disclose "a photoreceptor having a protective layer with high mechanical strength on its outermost surface as a method for improving the durability of the photoreceptor against wear."

[0004] Furthermore, Patent Document 5 discloses "a photoreceptor comprising toner particles, silicone oil surface-modified silica particles added externally to the toner particles, and a carrier." Furthermore, Patent Document 5 discloses that "the volume-average particle size of the carrier is 20 μm or more and 35 μm or less, and the ratio of silicon elements derived from silicone oil to silicon elements derived from silica present on the surface of the carrier is 0.05 or more and 0.2 or less." [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3287678 [Patent Document 2] Japanese Patent Publication No. 2005-234546 [Patent Document 3] Japanese Patent Publication No. 2000-66424 [Patent Document 4] Patent No. 6729017 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an image forming apparatus that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B), described later, exceeds 0.25. [Means for solving the problem]

[0007] The means for solving the problem include the following aspects: <1> Electrophotographic photoreceptor, A charging device having a charging member that contacts the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, A transfer device for transferring a toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium, Equipped with, An image forming apparatus in which, when the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A originating from the Si-C stretching of the silicone oil and the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less. <2> The aforementioned peak intensity ratio (A / B) is 0.21 or less. <1> The image forming apparatus described above. <3> The contact width of the contact portion between the electrophotographic photoreceptor and the charging member in the rotational direction of the electrophotographic photoreceptor is 0.31 mm or more and 0.58 mm or less. <1> or <2> The image forming apparatus described above. <4> The aforementioned contact width is 0.35 mm or more and 0.56 mm or less. <3> The image forming apparatus described above. <5> The surface roughness Rz of the charging member is 2.5 μm or more and 6.8 μm or less. <1> ~ <4> An image forming apparatus as described in any one of the items. <6> The surface roughness Rz of the charging member is 3.2 μm or more and 5.9 μm or less. <5> The image forming apparatus described above. <7> The electrophotographic photoreceptor has a conductive substrate, a photosensitive layer, and a protective layer in this order. The protective layer is a cured film made of a cured product of a composition containing a curing agent and a reactive group-containing charge transport material that reacts with the curing agent. <1> ~ <6> An image forming apparatus as described in any one of the items. <8> The curing agent is at least one compound selected from the group consisting of compounds having a guanamine structure and compounds having a melamine structure. The reactive group-containing charge transport material is a charge transport material having at least one group selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH. <7> The image forming apparatus described above. <9> The curing agent is a curable phenolic resin, The reactive group-containing charge transport material is a charge transport material having at least one group selected from the group consisting of hydroxyalkyl groups, hydroxyalkoxy groups, and hydroxyphenyl groups. <7> The image forming apparatus described above. <10> A charging device having a charging member that contacts the surface of an electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, Equipped with, When the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A originating from the Si-C stretching of the silicone oil and the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less. A process cartridge that is attached to and detached from an image forming apparatus. [Effects of the Invention]

[0008] <1> According to the invention, an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.25. <2> According to the invention, an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.21. <3> According to the invention, an image forming apparatus is provided that suppresses streaky image defects and fogging compared to cases where the contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the rotational direction of the electrophotographic photoreceptor is less than 0.31 mm or greater than 0.58 mm. <4> According to the invention, an image forming apparatus is provided that suppresses streaky image defects and fogging compared to cases where the contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the rotational direction of the electrophotographic photoreceptor is less than 0.35 mm or greater than 0.56 mm. <5> According to the invention, an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to cases where the surface roughness Rz of the charged member is less than 2.5 μm or greater than 6.8 μm. <6> According to the invention, an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to cases where the surface roughness Rz of the charged member is less than 3.2 μm or greater than 5.9 μm.

[0009] <7> , <8> or <9> According to the invention, compared to the case where the peak intensity ratio (A / B) exceeds 0.25, an image forming apparatus is provided that suppresses fogging along with streaky image defects, even when a photoreceptor has a protective layer made of a cured film. <10> According to the invention, a process cartridge is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.25. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 2] This is a schematic cross-sectional view showing an example of the layer configuration of an electrophotographic photoreceptor in an image forming apparatus according to this embodiment. [Figure 3] This is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photoreceptor in the image forming apparatus according to this embodiment. [Figure 4] This is a schematic diagram illustrating the contact width between the photoreceptor and the charged component in the direction of rotation of the photoreceptor. [Modes for carrying out the invention]

[0011] The following describes in detail an example embodiment of the present invention. These descriptions and examples are illustrative and do not limit the scope of the invention. In numerical ranges described stepwise within this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0012] Each component may contain multiple types of the relevant substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0013] In this specification, "electrophotographic photoreceptor" is also referred to as "photoreceptor." "Electrostatic image developer" is also called "developer."

[0014] <Image forming apparatus> The image forming apparatus according to this embodiment comprises an electrophotographic photoreceptor, a charging device, an electrostatic image forming device, a developing device, and a transfer device. The charging device has a charging member that contacts the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor. The electrostatic image forming apparatus forms an electrostatic image on the surface of a charged electrophotographic photoreceptor. The developing device contains an electrostatic image developer and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image. The transfer device transfers the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the recording medium. The electrostatic image developer contains toner particles and a toner containing silicone oil surface-modified silica particles as an external additive. Furthermore, when the silicone oil and silica particles adhering to the surface of the charged member are measured using the total internal reflection method of an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A derived from the Si-C stretching of the silicone oil and the peak intensity B derived from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less.

[0015] The image forming apparatus according to this embodiment suppresses both streaky image defects and fogging through the above configuration. The reason for this is presumed to be as follows. "Flash" refers to the phenomenon where unintended, dot-like images appear on the image-forming surface of a recording medium.

[0016] When image formation is repeated over a long period, toner particles tend to slip through the cleaning blade (hereinafter also referred to as "blade") that cleans the photoreceptor. As a result, streaky image defects occur. When silicone oil surface-modified silica particles are applied as an external additive to the toner, an aggregated layer of the external additive (a so-called external additive dam) is more likely to form at the contact point between the photoreceptor and the blade. When an external additive dam is formed, it becomes less likely for toner particles to slip through. Therefore, it is desirable to supply a large amount of silicone oil surface-modified silica particles to the contact point between the photoreceptor and the blade. On the other hand, a phenomenon also occurs in which the external additive migrates from the photoreceptor to the charged component. When the supply amount of silicone oil surface-modified silica particles increases, the external additive is more likely to adhere to the charged component when the proportion of silicone oil is high. As a result, the charge on the photoreceptor generated in the discharge region before the contact point between the photoreceptor and the charged component is canceled out at the contact point. This lowers the potential of the photoreceptor, making fogging more likely to occur. The exact mechanism of this phenomenon is unknown, but it is thought that positive charges are induced in the silicone oil, which is an insulator, under high electric fields. Therefore, the negative charges on the photoreceptor are canceled out at the contact point between the photoreceptor and the charged material.

[0017] Therefore, in the image forming apparatus according to this embodiment, the peak intensity ratio (A / B) is set to 0.25 or less. This reduces the proportion of silicone oil when the external additive adheres to the charged member, even when the amount of silicone oil surface-modified silica particles supplied to the contact area between the photoreceptor and the blade is increased. As a result, streaky image defects are suppressed while fogging caused by silicone oil is less likely to occur.

[0018] From the above, it is presumed that the image forming apparatus according to this embodiment suppresses both streaky image defects and fogging.

[0019] Here, the image forming apparatus according to this embodiment is a well-known image forming apparatus such as a direct transfer apparatus that directly transfers a toner image formed on the surface of a photoreceptor to a recording medium; an intermediate transfer apparatus that first transfers a toner image formed on the surface of a photoreceptor to the surface of an intermediate transfer body, and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a cleaning device that cleans the surface of an electrophotographic photoreceptor by bringing a cleaning blade into contact with it; and an anti-static device that removes static electricity by irradiating the surface of the photoreceptor with anti-static light after the transfer of the toner image and before it becomes charged. In the case of an intermediate transfer method apparatus, the transfer apparatus may be configured to include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of the photoreceptor to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0020] In addition, in the image forming apparatus according to this embodiment, the part including at least a photoreceptor, a charging device, and a developing device may constitute a unit for the image forming apparatus and may be a cartridge structure (i.e., a process cartridge) that can be attached to and detached from the image forming apparatus.

[0021] <Peak intensity ratio (A / B)> When silicone oil and silica particles adhering to the surface of a charged component are measured using the total internal reflection method with an infrared spectrophotometer, the peak intensity ratio (A / B) is 0.25 or less. Peak intensity A is the peak intensity A originating from the Si-C expansion of the silicone oil. The peak originating from the Si-C expansion of the silicone oil corresponds to a wavenumber of 803 cm⁻¹. -1 This is the peak. Peak intensity B is the peak intensity B originating from the Si-O-Si antisymmetric stretching of silica particles. The peak originating from the Si-O-Si antisymmetric stretching of silica particles is at wavenumber 1097 cm⁻¹. -1 This is the peak.

[0022] A peak intensity ratio (A / B) exceeding 0.25 indicates that excessive silicone oil is adhering to the charged component. This can lead to fogging caused by the silicone oil. The peak intensity ratio (A / B) is preferably 0.23 or less, and more preferably 0.21 or less.

[0023] Here, the peak intensity B derived from the Si-O-Si antisymmetric stretching of the silica particles is preferably 0.030 to 0.075, more preferably 0.040 to 0.070, and even more preferably 0.045 to 0.065. When the peak intensity B is 0.030 or higher, the amount of silicone oil surface-modified silica particles adhering to the charged material increases. In other words, the amount of silicone oil surface-modified silica particles supplied to the photoreceptor is also sufficient, making it easier to suppress streaky image defects. When the peak intensity B is 0.075 or less, the amount of excessive silicone oil surface-modified silica particles adhering to the charged component is reduced. As a result, charging failures caused by increased resistance of the charged component due to deposit accumulation are suppressed.

[0024] Peak intensities A and B can be adjusted according to the following: That is, the peak intensity ratio (A / B) can be adjusted according to the following: (1) Amount of silicone oil surface-modified silica particles added to toner particles (2) Amount of silicone oil adhering to silica particles and amount of free oil (3) Contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the direction of rotation of the electrophotographic photoreceptor

[0025] The measurements of peak intensity A and peak intensity B are as follows: Prepare the image forming apparatus to be measured. The photoreceptor, charging element, and developing device of the prepared image forming apparatus shall be unused. Next, under high temperature and high humidity conditions (28°C and 85% RH), an image forming apparatus is used to form a full-surface halftone image on an A4 sheet of paper. The full-surface halftone image is a color image formed by an image forming unit that includes a photoreceptor, a charging element, and a developing device. Image formation is then carried out until the photoreceptor has rotated 400,000 times. Afterward, the charged component is removed from the image forming apparatus. Then, the silicone oil and silica particles adhering to the surface of the extracted charged material are measured using the total internal reflection method of an infrared spectrophotometer. In other words, the peak intensity ratio (A / B) is a value calculated from peak intensities A and B measured after image formation under the above conditions.

[0026] Specifically, first, a section with an axial width of 1 cm and a circumferential width of 1 cm is cut from the charged material to prepare a measurement sample for the ATR method (total internal reflection measurement method). Next, the sample is measured using an infrared spectrophotometer under the following conditions, and then the infrared absorption spectrum is obtained. -Measurement conditions- • Equipment: Infrared spectrophotometer (PerkinElmer Spectrum3 FTIR, ATR unit, with Ge window) • Total number of times: 32 ·Resolution: 4cm -1 Wavelength range: 650 cm -1 Wave number over 4000cm -1 The following range • Spectral correction: ATR correction • Pressure gauge: 3

[0027] Then, determine the intensity of the next peak in the obtained infrared absorption spectrum. • The peak intensity A derived from the Si-C stretching of silicone oil is measured at wavenumber 803 cm⁻¹. -1 Peak intensity • The peak intensity B, derived from the Si-O-Si antisymmetric stretching of silica particles, is measured at wavenumber 1097 cm⁻¹. -1 Peak intensity

[0028] The procedure from sample preparation is repeated three times, and the arithmetic mean of each peak intensity is calculated. Then, the peak intensity ratio (A / B) is calculated from the arithmetic mean.

[0029] <Contact width> The contact width of the contact portion between the photoreceptor and the charged member in the direction of rotation of the photoreceptor is 0.30 mm or more and 0.60 mm or less, preferably 0.31 mm or more and 0.58 mm or less, more preferably 0.35 mm or more and 0.56 mm or less, and even more preferably 0.40 mm or more and 0.54 mm or less. Reducing the contact width to 0.58 mm or less makes it easier to control the peak intensity ratio (A / B) within the above range. Silica particles migrate from the photoreceptor to the charged material due to physical and electrostatic adhesion through contact with the charged material. In contrast, silicone oil migrates from the photoreceptor to the charged material due to physical adhesion through contact with the charged material. Therefore, by reducing the contact width to 0.58 mm or less, the amount of silicone oil migrated relative to the amount of silica particles migrated decreases. This makes it easier to control the peak intensity ratio (A / B) within the above range. On the other hand, by making the contact width 0.31 mm or more, excessive reduction in contact width is suppressed, and image density unevenness is reduced.

[0030] Here, the contact width is the length along the circumferential direction of the photoreceptor in the region where the photoreceptor and the charged member are in contact (see Lc in Figure 4). In Figure 4, PH represents the photoreceptor, CM represents the charging member, and Lc represents the contact width of the contact area between the photoreceptor and the charging member in the direction of rotation of the photoreceptor.

[0031] The contact width can be adjusted by the hardness of the charged component and the spring load that presses the charged component against the photoreceptor.

[0032] <Surface roughness of the charged material> The surface roughness Rz of the charged member is typically between 2.0 μm and 7.0 mm, preferably between 6.8 μm and 2.5 μm and 6.8 μm, more preferably between 3.2 μm and 5.9 μm, and even more preferably between 4.0 μm and 5.9 μm. When the surface roughness Rz of the charged component is within the above range, it becomes easier to control the peak intensity ratio (A / B) within that range. This is because even if silicone oil transferred from the photoreceptor adheres to the convex parts that are in direct contact with the photoreceptor, it is thought to be absorbed by the cleaning roll or swept out into the concave parts.

[0033] The surface roughness Rz (ten-point average roughness) of the charged material shall be measured using a surface roughness meter in accordance with JIS B0601-1994 under the following conditions. • Evaluation length Ln: 4mm • Standard length L: 0.8 mm • Cutoff value: 0.8mm

[0034] <Configuration of an image forming apparatus> The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0035] Figure 1 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. As shown in Figure 1, the image forming apparatus 10 according to this embodiment is provided with, for example, a photoreceptor 12. The photoreceptor 12 is cylindrical and is connected to a drive unit 27 such as a motor via a drive force transmission member (not shown) such as a gear, and is rotationally driven by the drive unit 27 around a rotation axis indicated by a black dot. In the example shown in Figure 1, it is rotationally driven in the direction of arrow A.

[0036] Around the photoreceptor 12, for example, a charging device 15 (an example of a charging device), an electrostatic image forming device 16 (an example of an electrostatic image forming device), a developing device 18 (an example of a developing device), a transfer device 31 (an example of a transfer device), a cleaning device 22 (an example of a cleaning device), and a static elimination device 24 are arranged in order along the rotational direction of the photoreceptor 12. The image forming apparatus 10 also includes a fixing device 26 having a fixing member 26A and a pressurizing member 26B positioned in contact with the fixing member 26A. The image forming apparatus 10 also has a control device 36 that controls the operation of each device (each part). The unit including the photoreceptor 12, charging device 15, electrostatic image forming device 16, developing device 18, transfer device 31, and cleaning device 22 corresponds to the image forming unit.

[0037] In the image forming apparatus 10, at least the photoreceptor 12 may be provided as a process cartridge integrated with other devices.

[0038] The details of each device (part) of the image forming apparatus 10 are described below. However, reference numerals are omitted.

[0039] [Electrophotographic photoconductor] The photoreceptor in the image forming apparatus according to this embodiment has, for example, a conductive substrate, a photosensitive layer, and a protective layer in this order. The photosensitive layer may be a single-layer photosensitive layer that integrates the functions of a charge generating material and a charge transport material within the same photosensitive layer, or it may be a multilayer photosensitive layer with separate functions having a charge generating layer and a charge transport layer. When the photosensitive layer is a multilayer photosensitive layer, the order of the charge generating layer and the charge transport layer is not particularly limited. The photoreceptor preferably has a configuration in which a charge generating layer, a charge transport layer, and a protective layer are arranged in this order on a conductive substrate. The photoreceptor may also contain layers other than these. Figure 2 is a schematic cross-sectional view showing an example of the layer configuration of a photoreceptor in an image forming apparatus according to this embodiment. The photoreceptor 107A has a structure in which a base layer 101 is provided on a conductive substrate 104, and a charge generation layer 102, a charge transport layer 103, and a protective layer 106 are sequentially formed thereon. In the photoreceptor 107A, a photosensitive layer 105 is configured in which the functions of the charge generation layer 102 and the charge transport layer 103 are separated. Figure 3 is a schematic cross-sectional view showing another example of the layer configuration of a photoreceptor in an image forming apparatus according to this embodiment. The photoreceptor 107B shown in Figure 3 has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a photosensitive layer 105 and a protective layer 106 are formed sequentially. In the photoreceptor 107B, a single-layer photosensitive layer is constructed in which a charge generating material and a charge transporting material are contained in the same photosensitive layer 105 and their functions are integrated. The photoreceptor may or may not have an undercoat layer 101. Furthermore, the photoreceptor may or may not be provided with a protective layer 106.

[0040] Details of each layer of the photoreceptor in the image forming apparatus according to this embodiment will be described below.

[0041] [Charging device] The charging device 15 charges the surface of the photoreceptor 12. The charging device 15 is, for example, provided in contact with the surface of the photoreceptor 12. The charging device 15 comprises a charging member 14 that charges the surface of the photoreceptor 12, and a power supply 28 that applies a charging voltage to the charging member 14. The power supply 28 is electrically connected to the charging member 14.

[0042] Examples of the charging members 14 of the charging device 15 include a contact-type charger using a conductive charging roll. Specifically, as the charging member 14 of the charging device 15, a well-known charging roll can be used, which has a base material, an elastic layer, and a surface layer arranged in that order.

[0043] [Electrostatic image forming device] The electrostatic image forming apparatus 16 forms an electrostatic image on the surface of the charged photoreceptor 12. Specifically, for example, the electrostatic image forming apparatus 16 irradiates the surface of the photoreceptor 12, which has been charged by the charging member 14, with light L modulated based on the image information of the image. The electrostatic image forming apparatus 16 then forms an electrostatic image on the photoreceptor 12 that corresponds to the image information.

[0044] Examples of electrostatic image forming apparatus 16 include optical equipment having a light source that exposes an image-like object with light such as semiconductor laser light, LED light, or liquid crystal shutter light.

[0045] [Developing equipment] The developing device 18 is located, for example, downstream of the photoreceptor 12 in the rotational direction from the irradiation position of light L by the electrostatic image forming device 16. The developing device 18 has a storage section for containing the developer. This storage section contains a developer containing toner. The toner is stored, for example, in a charged state within the developing device 18.

[0046] The developing apparatus 18, for example, houses a developer containing toner and includes a developing member 18A and a power supply 32. The developing member 18A is electrically connected to the power supply 32, for example. The developing component 18A develops the electrostatic image formed on the surface of the photoreceptor 12 using a developer containing toner. The power supply 32 applies a developing voltage to the developing element 18A.

[0047] The developing member 18A of the developing device 18 is selected according to the type of developer. An example of the developing member 18A is a developing roll having a developing sleeve with a magnet built in.

[0048] The developing device 18 (including the power supply 32) is electrically connected to, for example, a control device 36 provided in the image forming apparatus 10. The developing device 18 is driven and controlled by the control device 36 to apply a developing voltage to the developing member 18A. The developing member 18A, to which the developing voltage has been applied, is charged to a developing potential corresponding to the developing voltage. The developing member 18A, charged to the developing potential, then holds, for example, the developer contained in the developing device 18 on its surface. The developing member 18A then supplies toner contained in the developer from inside the developing device 18 to the surface of the photoreceptor 12. On the surface of the photoreceptor 12 to which the toner has been supplied, the formed electrostatic charge image is developed as a toner image.

[0049] [Transfer device] The transfer device 31 is provided, for example, downstream of the developing member 18A in the rotational direction of the photoreceptor 12. The transfer device 31 comprises, for example, a transfer member 20 and a power supply 30. The transfer member 20 transfers the toner image formed on the surface of the photoreceptor 12 to the recording medium 30A. The transfer member 20 is, for example, cylindrical in shape and transports the recording medium 30A between itself and the photoreceptor 12. The transfer member 20 is electrically connected to, for example, the power supply 30. The power supply 30 includes a power supply 30 that applies a transfer voltage to the transfer member 20.

[0050] Examples of the transfer member 20 include a contact-type transfer charger or a non-contact-type transfer charger. Examples of contact-type transfer chargers include those using belts, rollers, films, rubber cleaning blades, etc. Examples of non-contact transfer chargers include known non-contact transfer chargers such as scorotron transfer chargers or corotron transfer chargers that utilize corona discharge.

[0051] The transfer device 31 (including the power supply 30) is electrically connected, for example, to a control device 36 provided in the image forming apparatus 10. The transfer device 31 is driven and controlled by the control device 36 to apply a transfer voltage to the transfer member 20. The transfer member 20, to which the transfer voltage has been applied, is charged to a transfer potential corresponding to the transfer voltage.

[0052] Specifically, for example, a transfer voltage with the opposite polarity to the toner that constitutes the toner image formed on the photoreceptor 12 is applied to the transfer member 20 from the power supply 30 of the transfer device 31. A transfer electric field is formed in the region where the photoreceptor 12 and the transfer member 20 face each other (see transfer region 32A in Figure 1). The transfer electric field is a transfer electric field with an electric field strength that moves each toner that constitutes the toner image on the photoreceptor 12 from the photoreceptor 12 to the transfer member 20 side by electrostatic force.

[0053] The recording medium 30A is housed in a housing (not shown), for example. The recording medium 30A is transported from the housing along a transport path 34 by a plurality of transport members (not shown). The recording medium 30A reaches the transfer region 32A, which is the region where the photoreceptor 12 and the transfer member 20 face each other. In the example shown in Figure 1, the recording medium 30A is transported in the direction of arrow B. Once the recording medium 30A reaches the transfer region 32A, the toner image on the photoreceptor 12 is transferred to the recording medium 30A by a transfer electric field formed in the region by the transfer member 20, for example. That is, for example, the toner is transferred onto the recording medium 30A by the movement of toner from the surface of the photoreceptor 12 to the recording medium 30A. The toner image on the photoreceptor 12 is then transferred onto the recording medium 30A by the transfer electric field.

[0054] [Cleaning device] The cleaning device 22 is located downstream of the transfer area 32A in the rotational direction of the photoreceptor 12. After the toner image has been transferred to the recording medium 30A, the cleaning device 22 cleans any residual toner adhering to the photoreceptor 12. In addition to residual toner, the cleaning device 22 also cleans any other adhering substances such as paper dust.

[0055] The cleaning device 22 has a cleaning blade 22A, and removes deposits from the surface of the photoreceptor 12 by bringing the tip of the cleaning blade 22A into contact with the photoreceptor 12 in a direction opposite to the rotation direction of the photoreceptor 12.

[0056] The cleaning blade 22A is an elastic plate-like object. The materials used to construct the cleaning blade 22A include, for example, elastic materials such as silicone rubber, fluororubber, ethylene-propylene-diene rubber, and polyurethane rubber. Among these, polyurethane rubber is preferred because it exhibits excellent mechanical properties such as abrasion resistance, chipping resistance, and creep resistance.

[0057] The cleaning blade 22A has a support member attached to the side opposite to the side that contacts the photoreceptor 12. The cleaning blade 22A is supported by the support member. The support member presses the cleaning blade 22A against the photoreceptor 12 with the aforementioned pressure. The support member can be made of a metal material such as aluminum or stainless steel. There may also be an adhesive layer between the support member and the cleaning blade 22A, made of an adhesive or the like, to bond the two together. The cleaning device may include known components other than the cleaning blade 22A and the support member that supports it.

[0058] [Static eliminator] The static elimination device 24 is located, for example, downstream of the cleaning device 22 in the rotational direction of the photoreceptor 12. After transferring the toner image, the static elimination device 24 exposes the surface of the photoreceptor 12 to eliminate static electricity. Specifically, for example, the static elimination device 24 is electrically connected to a control device 36 provided in the image forming apparatus 10. The static elimination device 24 is driven and controlled by the control device 36 to expose the entire surface of the photoreceptor 12 (specifically, for example, the entire image forming area) to eliminate static electricity.

[0059] Examples of static elimination devices 24 include devices having a light source such as a tungsten lamp that emits white light or a light-emitting diode (LED) that emits red light.

[0060] [Fusing device] The fixing device 26 is provided, for example, downstream of the transfer area 32A in the transport direction of the transport path 34 of the recording medium 30A. The fixing device 26 includes a fixing member 26A and a pressurizing member 26B positioned in contact with the fixing member 26A. The fixing device 26 fixes the toner image transferred onto the recording medium 30A at the contact point between the fixing member 26A and the pressurizing member 26B. Specifically, for example, the fixing device 26 is electrically connected to a control device 36 provided in the image forming apparatus 10. The fixing device 26 is driven and controlled by the control device 36 to fix the toner image transferred onto the recording medium 30A to the recording medium 30A by heat and pressure.

[0061] Examples of the fixing device 26 include known fixing devices such as hot roller fixing devices and oven fixing devices. Specifically, for example, the fixing device 26 may be a well-known fixing device comprising a fixing member 26A and a pressurizing member 26B. Examples of the fixing member 26A include a fixing roll or a fixing belt. Examples of the pressurizing member 26B include a pressurizing roll or a pressurizing belt.

[0062] Here, the recording medium 30A is transported along the transport path 34 and passes through the area (transfer area 32A) where the photoreceptor 12 and the transfer member 20 face each other. In this area, the toner image is transferred to the recording medium 30A. After that, the recording medium 30A is transported further along the transport path 34 by a transport member (not shown), for example, to the installation position of the fuser device 26. Then, the fuser device 26 fixes the toner image on the recording medium 30A.

[0063] The recording medium 30A, on which the image has been formed by fixing the toner image, is discharged to the outside of the image forming apparatus 10 by a plurality of transport members (not shown in the figure). The photoreceptor 12 is then discharged by the static elimination device 24 and then recharged to a charging potential by the charging device 15.

[0064] [Operation of the image forming apparatus] An example of the operation of the image forming apparatus 10 according to this embodiment will be described. Note that various operations of the image forming apparatus 10 are performed by a control program executed in the control device 36.

[0065] The image forming operation of the image forming apparatus 10 will be described. First, the surface of the photoreceptor 12 is charged by the charging device 15. The electrostatic image forming device 16 exposes the charged surface of the photoreceptor 12 based on image information. This forms an electrostatic image on the photoreceptor 12 corresponding to the image information. In the developing device 18, the electrostatic image formed on the surface of the photoreceptor 12 is developed with a developer containing toner. This forms a toner image on the surface of the photoreceptor 12. In addition, fatty acid metal salt particles are added to the developer (and its toner) contained in the developing device 18, and these fatty acid metal salt particles are supplied to the surface of the photoreceptor 12 along with the toner. In the transfer device 31, the toner image formed on the surface of the photoreceptor 12 is transferred to the recording medium 30A. The toner image transferred to the recording medium 30A is fixed by the fuser device 26. Meanwhile, the surface of the photoreceptor 12 after the toner image has been transferred is cleaned by the cleaning blade 22A in the cleaning device 22, and then static electricity is removed by the static elimination device 24. Some of the fatty acid metal salt particles supplied to the surface of the photoreceptor 12 in the developing device 18 remain on the surface of the photoreceptor 12 even after the toner image has been transferred by the transfer device 31, and are supplied to the contact position between the cleaning blade 22A and the photoreceptor 12. Therefore, the presence of a fatty acid metal salt at the contact point between the cleaning blade 22A and the photoreceptor 12 enables the cleaning blade 22A to achieve high cleaning performance.

[0066] [Each layer of the electrophotographic photoreceptor] Next, the details of each layer of the photoreceptor in the image forming apparatus according to this embodiment will be described. However, reference numerals will be omitted when describing each layer of the photoreceptor.

[0067] (Conductive substrate) Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a volume resistivity of 10⁻¹⁰. 13 This refers to a value less than Ω·cm.

[0068] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. While roughening to prevent interference fringes is not particularly necessary when using non-interfering light as the light source, it is beneficial for extending the lifespan by suppressing the occurrence of defects due to surface irregularities of the conductive substrate.

[0069] Methods for roughening a surface include, for example, wet honing, which involves suspending an abrasive in water and spraying it onto a conductive substrate; centerless grinding, which involves pressing a conductive substrate against a rotating grinding wheel and continuously grinding it; and anodizing.

[0070] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive substrate, to form a layer on the surface of the conductive substrate, and then roughen the surface with the particles dispersed in that layer.

[0071] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive substrate (e.g., aluminum) by anodizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0072] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0073] The conductive substrate may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0074] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0075] (Underlying layer) The underlying layer is, for example, a layer containing inorganic particles and a binder resin.

[0076] Examples of the inorganic particles include those having a powder resistance (volume resistivity) of 10 2 Ω·cm or more and 10 11 Ω·cm or less. Among these, examples of the inorganic particles having the above resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and particularly, zinc oxide particles are preferable.

[0077] The specific surface area of the inorganic particles by the BET method is, for example, 10 m 2 / g or more. The volume average particle diameter of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

[0078] The content of the inorganic particles is preferably, for example, 10 mass% or more and 80 mass% or less, more preferably 40 mass% or more and 80 mass% or less, based on the binder resin.

[0079] The inorganic particles may be surface-treated. The inorganic particles may be used by mixing two or more kinds of those having different surface treatments or different particle diameters.

[0080] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, and the like. Particularly, silane coupling agents are preferable, and silane coupling agents having an amino group are more preferable.

[0081] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0082] Silane coupling agents may be used in combination of two or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0083] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0084] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0085] In this case, it is preferable for the underlayer to contain electron-accepting compounds (acceptor compounds) along with inorganic particles, from the viewpoint of improving the long-term stability of electrical properties and carrier blocking ability.

[0086] Examples of electron-accepting compounds include electron-transporting substances such as compounds having anthraquinone structures; quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples of preferred compounds include anthraquinone, alizarin, quinizalin, anthralphine, purpurin, and their derivatives.

[0087] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0088] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0089] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0090] The wet method involves dispersing inorganic particles in a solvent using, for example, a stirrer, ultrasonic disperser, sand mill, attritor, or ball mill, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed, and the electron-accepting compound adheres to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0091] Furthermore, the attachment of the electron-accepting compound may be performed before or after surface treatment with a surface treatment agent on the inorganic particles, or it may be performed simultaneously with the attachment of the electron-accepting compound and surface treatment with the surface treatment agent.

[0092] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0093] Examples of known polymer compounds used as the binder resin for the undercoat include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, alkyd resin, epoxy resin, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Examples of binder resins used in the undercoat include charge-transporting resins having charge-transporting groups, conductive resins (e.g., polyaniline), and the like.

[0094] Among these, a resin insoluble in the coating solvent of the upper layer is preferred as the binder resin used for the undercoat layer. In particular, a resin obtained by the reaction of a curing agent with at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, and epoxy resin is preferred. When using two or more of these binder resins in combination, the mixing ratio is set as needed.

[0095] The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include electron-transporting pigments such as polycyclic condensation and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as additives.

[0096] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0097] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0098] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0099] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0100] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0101] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0102] There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0103] Solvents for preparing the coating solution for forming the undercoat include known organic solvents such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0104] Known methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0105] Conventional methods for applying the undercoating solution onto a conductive substrate include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0106] The thickness of the undercoat layer is preferably set to a range of 15 μm or more, and more preferably 20 μm to 50 μm.

[0107] (Middle class) Although not shown in the diagram, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0108] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0109] There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating are used to form the intermediate layer.

[0110] The thickness of the intermediate layer is preferably set to a range of 0.1 μm to 3 μm, for example. The intermediate layer may also be used as a base layer.

[0111] (Charge generation layer) The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable when using non-coherent light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0112] Examples of charge-generating materials include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthonthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0113] Among these, in order to accommodate laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine are more preferable.

[0114] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthoten; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0115] The above charge generating material may also be used when using non-coherent light sources such as LEDs and organic EL image arrays, which have a central emission wavelength between 450 nm and 780 nm.

[0116] When n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark currents are less likely to occur, and image defects called black spots can be suppressed even in thin films. Furthermore, the n-type is determined using the commonly used time-of-flight method, based on the polarity of the photocurrent that flows. Those that are more likely to carry electrons as carriers than holes are classified as n-type.

[0117] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic divalent carboxylic acids, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Here, "insulating properties" refers to a volume resistivity of 10 13 This refers to a value of Ω·cm or greater. These binder resins can be used individually or in combination of two or more types.

[0118] Furthermore, the mixing ratio of the charge-generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass ratio.

[0119] The charge generation layer may also contain other well-known additives.

[0120] The formation of the charge generation layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge generation layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused aromatic pigments or perylene pigments as the charge generation material.

[0121] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0122] Methods for dispersing particles (e.g., charge-generating materials) in a coating solution for forming a charge-generating layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, which disperse the dispersion by causing liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, which disperse the dispersion by penetrating fine channels under high pressure. Furthermore, during this dispersion, it is effective to set the average particle size of the charge-generating material in the coating solution for forming the charge-generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0123] Conventional methods for applying the charge-generating layer forming coating solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0124] The thickness of the charge generation layer is preferably set to a range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0125] (charge transport layer) The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0126] Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds, which are electron transport compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used individually or in combination of two or more, but are not limited to these.

[0127] As charge transport materials, from the viewpoint of charge mobility, the triarylamine derivative shown in the following structural formula (a-1) and the benzidine derivative shown in the following structural formula (a-2) are preferred.

[0128] [ka]

[0129] In structural formula (a-1), Ar T1 Ar T2 , and Ar T3 Each is independently a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) indicates R T4 , R T5 , R T6 , R T7 , and R T8 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0130] [ka]

[0131] In structural formula (a-2), R T91 and R T92 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 Each of these independently consists of a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, and -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) shows R T12 , R T13 , R T14 , R T15 and R T16 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer between 0 and 2. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0132] Here, among the triarylamine derivative represented by structural formula (a-1) and the benzidine derivative represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0133] As polymer charge transport materials, known charge transport materials such as poly-N-vinylcarbazole and polysilane can be used. Polyester-based polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone, or it may be used in combination with a binder resin.

[0134] Examples of binder resins used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, and polysilane. Among these, polycarbonate resin or polyarylate resin is preferred as the binder resin. These binder resins can be used individually or in combination of two or more. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0135] The charge transport layer may also contain other well-known additives.

[0136] The formation of the charge transport layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0137] Suitable solvents for preparing the coating solution for forming the charge transport layer include common organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents can be used individually or in mixtures of two or more.

[0138] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0139] The thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0140] (protective layer) A protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during electrostatic charging, or to further improve the mechanical strength of the photosensitive layer. Therefore, it is preferable to apply a protective layer composed of a cured film (crosslinked film). Examples of such layers include those shown in 1) or 2) below.

[0141] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton within the same molecule (i.e., a layer containing a polymer or crosslinked form of the reactive group-containing charge transport material). 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material containing reactive groups that does not have a charge transport skeleton but has reactive groups (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked form of the non-charge transport material containing reactive groups).

[0142] The reactive groups in the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [where R represents an alkyl group], -NH2, -SH, -COOH, and -SiR. Q1 3-Qn (OR Q2 ) Qn [However, R Q1 R represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group. Q2 Examples of well-known reactive groups include hydrogen atoms, alkyl groups, and trialkylsilyl groups. Qn represents an integer from 1 to 3.

[0143] The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, for example, a functional group having at least one carbon double bond. Specifically, examples include groups containing at least one selected from vinyl groups, vinyl ether groups, vinyl thioether groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives. Among these, the chain polymerizable group is preferably a group containing at least one selected from vinyl groups, styryl groups (vinyl phenyl groups), acryloyl groups, methacryloyl groups, and their derivatives, due to its excellent reactivity.

[0144] The charge-transporting skeleton of the reactive group-containing charge-transporting material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors. Examples include skeletons derived from nitrogen-containing hole-transporting compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, in which the nitrogen atom is conjugated. Among these, the triarylamine skeleton is preferred.

[0145] These reactive groups and charge-transporting skeletons, including reactive group-containing charge transport materials, non-reactive charge transport materials, and reactive group-containing non-charge transport materials, can be selected from well-known materials.

[0146] In particular, the protective layer is preferably a cured film made from a cured product of a composition comprising a curing agent and a reactive group-containing charge transport material that reacts with the curing agent. Specifically, the following embodiments are given.

[0147] Embodiment A: Embodiment combining the following curing agent with the following reactive group-containing charge transport material. • Hardener A: At least one compound selected from the group consisting of compounds having a guanamine structure and compounds having a melamine structure. • Reactive group-containing charge transport material A: A charge transport material having at least one group selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH.

[0148] Embodiment B: Embodiment combining the following curing agent with the following reactive group-containing charge transport material. • Hardener B: Curable phenolic resin • Reactive group-containing charge transport material B: A charge transport material B having at least one group selected from the group consisting of hydroxyalkyl groups, hydroxyalkoxy groups, and hydroxyphenyl groups.

[0149] These protective layers, which consist of cured films using a hardening agent, are particularly hard and resistant to wear by the cleaning blade. Therefore, the oil derived from the silicone oil surface-modified silica particles tends to remain on the surface of the protective layer (i.e., the surface of the photoreceptor). This increases the amount of silicone oil that migrates to the charged component. As a result, fogging is more likely to occur. In particular, if the amount of silicone oil surface-modified silica particles supplied to the contact area between the photoreceptor and the cleaning blade is increased in order to suppress streaky image defects, fogging is more likely to occur. However, in the image forming apparatus according to this embodiment, even when a protective layer consisting of a cured film using a curing agent is applied, fogging can be suppressed along with streaky image defects.

[0150] The components applied in Embodiment A and Embodiment B will be described below.

[0151] -Hardening agent A- The curing agent A is at least one compound selected from the group consisting of compounds having a guanamine structure and compounds having a melamine structure.

[0152] --Compounds containing a guanamine structure (hereinafter also referred to as "guanamine compounds")-- Guanamine compounds are compounds that have a guanamine skeleton (structure), and examples include acetoguanamine, benzoguanamine, formoguanamine, steroguanamine, spiloganamine, and cyclohexylguanamine.

[0153] The guanamine compound is preferably at least one of the compound represented by the following general formula (A) and its polymer. Here, the polymer is an oligomer polymerized using the compound represented by general formula (A) as a structural unit, and its degree of polymerization is, for example, 2 to 200 (preferably 2 to 100). The compound represented by general formula (A) may be used alone or in combination of two or more. In particular, the solubility in solvents is improved when two or more compounds represented by general formula (A) are used in combination or as a polymer (oligomer) using it as a structural unit.

[0154] [ka]

[0155] In general formula (A), R1 represents a linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 4 to 10 carbon atoms. R2 to R5 each independently represent hydrogen, -CH2-OH, or -CH2-O-R6. R6 represents hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms.

[0156] In general formula (A), the alkyl group representing R1 has 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 5 carbon atoms. The alkyl group may be linear or branched.

[0157] In general formula (A), the phenyl group representing R1 has 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms. Examples of substituents that can be substituted for the phenyl group include methyl, ethyl, and propyl groups.

[0158] In general formula (A), the alicyclic hydrocarbon group representing R1 has 4 to 10 carbon atoms, more preferably 5 to 8 carbon atoms. Examples of substituents that can be substituted for the alicyclic hydrocarbon group include methyl groups, ethyl groups, and propyl groups.

[0159] In general formula (A), in the "-CH2-O-R6" representing R2 to R5, the alkyl group representing R6 has 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms. The alkyl group may be linear or branched. Preferably, it is a methyl group, an ethyl group, a butyl group, etc.

[0160] The compound represented by general formula (A) is particularly preferably a compound in which R1 represents a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, and R2 to R5 each independently represent -CH2-O-R6. Furthermore, R6 is selected from a methyl group or an n-butyl group. It is preferable to do so.

[0161] The compound represented by general formula (A) can be synthesized, for example, using guanamine and formaldehyde by known methods (e.g., Experimental Chemistry Series, 4th edition, Vol. 28, p. 430).

[0162] Specific examples of compounds represented by general formula (A) include, for example, the compounds shown in paragraphs 0037 to 0038 of Japanese Patent Publication No. 2011-008117.

[0163] Examples of commercially available compounds represented by general formula (A) include Superbeccamine(R) L-148-55, Superbeccamine(R) 13-535, Superbeccamine(R) L-145-60, and Superbeccamine(R) TD-126 from DIC Corporation, and Nikalac BL-60 and Nikalac BX-4000 from Nippon Carbide Co., Ltd.

[0164] Furthermore, after synthesis or purchase of a commercially available product, the compound represented by general formula (A) (including the polymer) may be dissolved in a suitable solvent such as toluene, xylene, or ethyl acetate and washed with distilled water or deionized water, or removed by treatment with an ion exchange resin, in order to remove the effect of residual catalyst.

[0165] --Compounds containing a melamine structure (hereinafter also referred to as "melamine compounds")-- The melamine compound is a compound having a melamine skeleton (structure), and is particularly preferably at least one of the compound represented by the following general formula (B) and its polymer. Here, the polymer is an oligomer polymerized using the compound represented by general formula (B) as a structural unit, similar to general formula (A), and its degree of polymerization is, for example, 2 to 200 (preferably 2 to 100). The compound represented by general formula (B) or its polymer may be used alone or in combination of two or more. It may also be used in combination with the compound represented by general formula (A) or its polymer. In particular, when two or more compounds represented by general formula (B) are used in combination or as a polymer (oligomer) with it as a structural unit, the solubility in solvents is improved.

[0166] [ka]

[0167] In general formula (B), R6 ~R 11 These are, independently, a hydrogen atom, -CH2-OH, and -CH2-OR. 12 Show, R 12 This represents an alkyl group having 1 to 5 carbon atoms. This alkyl group may be branched, and specific examples include a methyl group, an ethyl group, and a butyl group.

[0168] The compound represented by general formula (B) can be synthesized, for example, using melamine and formaldehyde by known methods (for example, similar to the synthesis of melamine resin as described in Experimental Chemistry Series, 4th edition, Vol. 28, page 430).

[0169] Specific examples of compounds represented by general formula (B) include, for example, the compounds shown in paragraph 0046 of Japanese Patent Publication No. 2011-008117.

[0170] Examples of commercially available compounds represented by general formula (B) include Super Melami No. 90 manufactured by NOF Corporation, Super Beccamine(R) TD-139-60 manufactured by DIC Corporation, Yuban 2020 manufactured by Mitsui Chemicals, Sumitex Resin M-3 manufactured by Sumitomo Chemical Co., Ltd., and Nikalac MW-30 manufactured by Nippon Carbide Co., Ltd.

[0171] Furthermore, after synthesis or purchase of a commercially available product, the compound represented by general formula (B) (including the polymer) may be dissolved in a suitable solvent such as toluene, xylene, or ethyl acetate and washed with distilled water or deionized water, or removed by treatment with an ion exchange resin, in order to remove the effect of residual catalyst.

[0172] -Hardening agent B- The hardening agent B is a curable phenolic resin. Examples of curable phenolic resins include resins obtained by the reaction of phenols with formaldehyde. Specifically, curable phenolic resins include resol-type curable resins obtained by reacting phenols with an excess of formaldehyde using an alkaline catalyst, and novolac-type curable phenolic resins obtained by reacting phenols with an excess of formaldehyde using an acid catalyst.

[0173] Resol-type curable phenolic resins are soluble in alcohol and ketone solvents, and undergo three-dimensional crosslinking polymerization upon heating to form a cured product. Novolac-type curable phenolic resins do not harden when heated directly, but they produce a cured product when heated with a formaldehyde source. Examples of formaldehyde sources include paraformaldehyde and hexamethylenetetramine.

[0174] The curable phenolic resin can be any known curable phenolic resin and is not particularly limited.

[0175] -Reactive group-containing charge transport material A- The reactive group-containing charge transport material A is a charge transport material A having at least one group (hereinafter also called a reactive substituent) selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH. In particular, charge transport material A is preferably one having at least two (or even three) substituents selected from -OH, -OCH3, -NH2, -SH, and -COOH. In this way, increasing the reactive functional groups in charge transport material A increases the crosslinking density, resulting in a stronger crosslinked product, which in turn suppresses surface wear on the photoreceptor.

[0176] The charge transport material A is preferably a compound represented by the following general formula (I). F-((-R1-X) n1 R2-Y) n2 (I)

[0177] In general formula (I), F represents an organic group derived from a hole-transporting compound, R1 and R2 each independently represent a linear or branched alkylene group having 1 to 5 carbon atoms, n1 represents 0 or 1, and n2 represents an integer from 1 to 4. X represents -O-, -NH-, or -S-, and Y represents -OH, -OCH3, -NH2, -SH, or -COOH.

[0178] In general formula (I), preferred examples of compounds having hole transport ability in an organic group derived from a compound exhibiting hole transport ability represented by F are arylamine derivatives. Preferred examples of arylamine derivatives include triphenylamine derivatives and tetraphenylbenzidine derivatives.

[0179] Furthermore, the compound represented by general formula (I) is preferably the compound represented by general formula (II) below. The compound represented by general formula (II) is particularly excellent in terms of charge mobility, stability against oxidation, etc.

[0180] [ka]

[0181] In general formula (II), Ar 1 ~Ar 4 Each of these independently represents a substituted or unsubstituted aryl group, Ar 5 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted arylene group, and D is -(-R1-X) n1 R2 represents Y, where c independently represents 0 or 1, k independently represents 0 or 1, and the total number of D is between 1 and 4. In addition, R1 and R2 independently represent linear or branched alkylene groups with 1 to 5 carbon atoms, n1 represents 0 or 1, X represents -O-, -NH-, or -S-, and Y represents -OH, -OCH3, -NH2, -SH, or -COOH.

[0182] In general formula (II), D is represented by "-(-R1-X) n1"R2-Y" is the same as general formula (I), where R1 and R2 are each independently a linear or branched alkylene group having 1 to 5 carbon atoms. Further, n1 is preferably 1. Further, X is preferably -O-. Further, Y is preferably -OH. The total number of D in general formula (II) corresponds to n2 in general formula (I), and is preferably 2 or more and 4 or less, more preferably 3 or more and 4 or less. That is, in general formula (I) and general formula (II), when D is preferably 2 or more and 4 or less, more preferably 3 or more and 4 or less in one molecule, the crosslinking density increases and a crosslinked product with higher strength can be obtained, so that wear on the surface in the electrophotographic photoreceptor is suppressed.

[0183] In general formula (II), Ar 1 to Ar 4 is preferably any one of the following formulas (1) to (7). The following formulas (1) to (7) are shown together with "-(D) 1 to Ar <000(0066>that can be linked to. C "

[0184]

Chemical formula

[0185] In formulas (1) to (7), R 9 represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, and R 10 to R 12represents one kind selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, Ar represents a substituted or unsubstituted arylene group, D and c are the same as D and c in the general formula (II), s represents 0 or 1 respectively, and t represents an integer of 1 or more and 3 or less.

[0186] Here, as Ar in the formula (7), those represented by the following formula (8) or (9) are preferable.

Chemical formula

[0187] In the formulas (8) and (9), R 13 and R 14 each represent one kind selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t represents an integer of 1 or more and 3 or less.

[0188] Also, as Z' in the formula (7), those represented by any one of the following formulas (10) to (17) are preferable.

[0189]

Chemical formula

[0190] In the formulas (10) to (17), R 15 and R 16Each represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. W represents a divalent group, q and r represent integers from 1 to 10, and t represents an integer from 1 to 3.

[0191] In formulas (16) to (17) above, W is preferably one of the divalent bases represented by (18) to (26) below. However, in formula (25), u represents an integer between 0 and 3.

[0192] [ka]

[0193] Also, in general formula (II), Ar 5 When k is 0, Ar 1 ~Ar 4 The above-mentioned aryl groups (1) to (7) are exemplified in the explanation, and when k is 1, the above-mentioned aryl groups (1) to (7) are arylene groups obtained by removing a hydrogen atom.

[0194] Specific examples of compounds represented by general formula (I) include, for example, the compounds shown in paragraphs 0070 to 0077 of Japanese Patent Publication No. 2011-008117.

[0195] -Reactive group-containing charge transport material B- The reactive group-containing charge transport material B is a charge transport material B having at least one group selected from the group consisting of hydroxyalkyl groups, hydroxyalkoxy groups, and hydroxyphenyl groups.

[0196] Here, the hydroxyphenyl group may have substituents. Examples of substituents include halogen atoms, optionally substituted alkyl groups, optionally substituted alkoxy groups, optionally substituted aryl groups, and optionally substituted heterocyclic groups. Examples of the halogen atom include fluorine, chlorine, bromine, iodine, and the like. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, and the like. Examples of the alkoxy group include alkoxy such as methoxy group, ethoxy group, propoxy group, butoxy group, and the like. Examples of the aryl group include phenyl group, naphthyl group, anthryl group, pyrenyl group, and the like. Examples of the heterocyclic group include pyridyl group, thienyl group, furyl group, quinolyl group, and the like.

[0197] Charge transport material B having a -hydroxyalkyl group or a hydroxyalkoxy group Among the charge transport materials B, examples of the charge transport material B having a hydroxyalkyl group or a hydroxyalkoxy group include compounds represented by the following general formula (1), the following general formula (2), or the following general formula (3).

[0198]

Chemical formula

[0199] In general formula (1), R 11 , R 12 and R 13 each independently represent a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched. α, β and γ each independently represent a benzene ring which may have one or more halogen atoms as substituents, an alkyl group which may have substituents, an alkoxy group which may have substituents, an aryl group which may have substituents, or a heterocyclic group which may have substituents. a1, b1 and c1 are 1 or 0. m1 and n1 are 0 or 1.

[0200]

Chemical formula

[0201] In general formula (2), R 21 , R 22 and R 23Each independently represents a branched divalent hydrocarbon group having 1 to 8 carbon atoms. δ and ε each independently represent a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. a2, b2, and c2 are 1 or 0. m2, n2, and p2 are 0 or 1, and not all can be 0 at the same time. τ and υ each independently represent a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. Note that τ and υ may jointly form a ring via substituents.

[0202] [ka]

[0203] In general formula (3), R 31 , R 32 , R 33 and R 34 Each independently represents a branched divalent hydrocarbon group having 1 to 8 carbon atoms. Each independently represents a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. a3, b3, c3, and d3 are 1 or 0. m3, n3, and p3 are 0 or 1. Each independently represents a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. Note that φ and χ may jointly form a ring via substituents.

[0204] When a1, b1, and c1 in General Formula (1), a2, b2, and c2 in General Formula (2), or a3, b3, c3, and d3 in General Formula (3) are 0, the charge transporting material represented by General Formulas (1) to (3) is a charge transporting material having a hydroxyalkyl group. When a1, b1, and c1 in General Formula (1), a2, b2, and c2 in the above General Formula (2), or a3, b3, c3, and d3 in the above General Formula (3) are 1, the charge transporting material represented by General Formulas (1) to (3) is a charge transporting material having a hydroxyalkoxy group.

[0205] In General Formulas (1) to (3), R 11 ~R 13 、R 21 ~R 23 、and R 31 ~R 34 each independently represents a divalent hydrocarbon group (such as a methylene group, an ethylene group, a propylene group, a butylene group, etc.) which may be branched and has 1 to 8 carbon atoms.

[0206] In General Formulas (1) to (3), as the substituents that the benzene rings represented by α, β, γ, δ, ε, ζ, η, θ, and ι, and the benzene rings represented by τ, υ, φ, and χ may have, there are halogen atoms, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, and a heterocyclic group which may have a substituent. Note that τ and υ, and φ and χ may jointly form a cyclic structure such as a fluorene skeleton or a dihydrophenanthrene skeleton via the biphenyl skeleton to which each is bonded. Here, examples of the halogen atom include fluorine, chlorine, bromine, iodine, etc. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, and a pyrenyl group. Examples of the heterocyclic group include a pyridyl group, a thienyl group, a furyl group, and a quinolyl group.

[0207] In General Formulas (1) to (3), examples of the substituent that each group may have include alkyl groups such as methyl group, ethyl group, propyl group, and butyl group; aralkyl groups such as benzyl group, phenethyl group, and naphthylmethyl group; aromatic ring groups such as phenyl group, naphthyl group, anthryl group, pyrenyl group, fluorenyl group, carbazolyl group, dibenzofuryl group, and dibenzothiophenyl group; alkoxy groups such as methoxy group, ethoxy group, and propoxy group, aryloxy groups such as phenoxy group and naphthoxy group; halogen atoms such as fluorine, chlorine, bromine, and iodine; nitro group, cyano group, and the like.

[0208] Specific examples of the compounds represented by General Formulas (1) to (3) include the compounds shown in Paragraphs 0045 to 0067 of Patent No. 3740389. However, it is not limited to these compounds.

[0209] Charge transport material B having a -hydroxyphenyl group Among the charge transport materials B, examples of the charge transport material B having a hydroxyphenyl group include compounds represented by the following General Formula (4), the following General Formula (5), or the following General Formula (6).

[0210]

Chemical formula

[0211] In General Formula (4), R 41 represents a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched. R 42 represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a phenyl group which may have a substituent. Ar 41 and Ar 42 represent an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. Ar 43represents an optionally substituted arylene group or an optionally substituted heterocyclic group. m4 and n4 are independently 0 or 1, except when n4=0, then m4=0. κ and λ are independently a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group.

[0212] [ka]

[0213] In general formula (5), R 51 represents a divalent hydrocarbon group with 1 to 8 carbon atoms that may branch. 51 and Ar 52 μ represents an optionally substituted alkyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. μ and ν each independently represent a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. Note that μ and ν may jointly form a ring via substituents. m5 is 0 or 1.

[0214] [ka]

[0215] In general formula (6), R 61 and R 62 Each of these independently represents a branched divalent hydrocarbon group having 1 to 8 carbon atoms. 61ξ represents an optionally substituted alkyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. ξ, π, ρ, and σ each independently represent a benzene ring which may have one or more substituents: a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. Note that ξ and π, and ρ and σ may jointly form a ring via substituents. m6 and n6 are each independently 0 or 1.

[0216] In general formulas (4) to (6), R 41 , R 51 , R 61 and R 62 Each of these independently represents a divalent hydrocarbon group, such as a methylene group, ethylene group, propylene group, and butylene group, which may branch and have 1 to 8 carbon atoms. 42 This represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aralkyl group, or a phenyl group. Examples of alkyl groups include methyl, ethyl, propyl, and butyl groups. Examples of aralkyl groups include benzyl groups, phenethyl groups, and naphthylmethyl groups.

[0217] In general formulas (4) to (6), the substituents that the benzene ring represented by κ, λ, μ, ν, ξ, π, ρ, and σ may have include halogen atoms, optionally substituted alkyl groups, optionally substituted alkoxy groups, optionally substituted aryl groups, or optionally substituted heterocyclic groups. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Examples of alkyl groups include methyl, ethyl, propyl, and butyl groups. Examples of alkoxy groups include methoxy, ethoxy, propoxy, and butoxy groups. Examples of aryl groups include phenyl, naphthyl, anthuryl, and pyrenyl groups. Examples of heterocyclic groups include pyridyl, thienyl, furyl, and quinolyl groups.

[0218] In general formulas (4) to (6), μ and ν, ξ and π, and ρ and σ may jointly form cyclic structures such as a fluorene skeleton or a dihydrophenanthrene skeleton via substituents to which they are bonded.

[0219] In general formulas (4) to (6), Ar 41 Ar 42 Ar 51 Ar 52 and Ar 61 This represents an optionally substituted alkyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Examples of alkyl groups include methyl, ethyl, propyl, and butyl groups. Examples of aralkyl groups include benzyl groups, phenethyl groups, and naphthylmethyl groups. Examples of aryl groups include phenyl, naphthyl, anthuryl, and pyrenyl groups. Examples of heterocyclic groups include pyridyl, thienyl, furyl, and quinolyl groups.

[0220] In general formulas (4) to (6), Ar 43 This represents an arylene group which may have substituents, or a divalent heterocyclic group. Examples of allerene groups include phenylene, naphthylene, anthrylene, and pyrenylene groups. Examples of divalent heterocyclic groups include pyridylene groups and thienylene groups.

[0221] In general formulas (4) to (6), possible substituents on each group include alkyl groups such as methyl, ethyl, propyl, and butyl groups; aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups; aromatic ring groups such as phenyl, naphthyl, anthuryl, pyrenyl, fluorenyl, carbazolyl, dibenzofuryl, and dibenzothiophenyl groups; alkoxy groups such as methoxy, ethoxy, and propoxy groups; aryloxy groups such as phenoxy and naphthoxy groups; halogen atoms such as fluorine, chlorine, bromine, and iodine; and nitro and cyano groups.

[0222] Specific examples of compounds represented by general formulas (4) to (6) include those described in paragraphs 0082 to 0103 of Japanese Patent No. 3740389. However, the invention is not limited to these compounds.

[0223] The protective layer may also contain other well-known additives.

[0224] There are no particular restrictions on the formation of the protective layer, and well-known formation methods can be used. For example, it can be formed by adding the above components to a solvent to create a protective layer coating, forming a coating film, drying the coating film, and then performing a curing treatment such as heating as necessary.

[0225] Solvents for preparing coating solutions for forming a protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents can be used individually or in combination of two or more. Furthermore, the coating solution for forming the protective layer may be a solvent-free coating solution.

[0226] Conventional methods for applying a protective layer-forming coating solution onto a photosensitive layer (e.g., a charge transport layer) include immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0227] The thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, and more preferably within the range of 2 μm to 10 μm.

[0228] (Single-layer photosensitive layer) A single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer comprising a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. Furthermore, the content of the charge-generating material in the single-layer photosensitive layer is preferably 0.1% to 10% by mass, and more preferably 0.8% to 5% by mass, relative to the total solid content. In addition, the content of the charge-transporting material in the single-layer photosensitive layer is preferably 5% to 50% by mass, relative to the total solid content. The method for forming a single-layer photosensitive layer is the same as the method for forming a charge generation layer or a charge transport layer. The thickness of the single-layer photosensitive layer is, for example, preferably 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[0229] [Developer] Next, the developer contained in the developing apparatus (hereinafter also referred to as "the developer according to this embodiment") in the image forming apparatus according to this embodiment will be described.

[0230] The developer according to this embodiment may be a one-component developer containing only toner, or a two-component developer containing a mixture of toner and carrier.

[0231] (toner) The toner contains toner particles and silicone oil surface-modified silica particles as an external additive.

[0232] -Toner particles- The toner particles may include, for example, a binder resin (e.g., polyester resin), and may also contain colorants, release agents, and other additives. Each component of the toner particles can be selected from well-known materials.

[0233] The toner particles may be single-layer toner particles, or they may be toner particles with a so-called core-shell structure, consisting of a core (core particle) and a coating layer (shell layer) that covers the core. Here, the core-shell structure of the toner particles may consist of, for example, a core portion comprising a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer comprising a binder resin.

[0234] The volume-average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0235] The average particle size and particle size distribution indices of the toner particles are measured using the Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using the ISOTON-II (manufactured by Beckman Coulter). For measurement, add 0.5 mg to 50 mg of the sample to be measured in 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. Add this to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter of 2 μm to 60 μm is then measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the measured particle size distribution, a cumulative distribution of volume and number is drawn for each divided particle size range (channel) from the smallest diameter side. The particle size at which the cumulative total reaches 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size at which the cumulative total reaches 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size at which the cumulative total reaches 84% ​​is defined as the volume particle size D84v and the number particle size D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 The GSDp index is (D84p / D16p) 1 / 2 It is calculated as follows.

[0236] The average circularity of the toner particles is preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0237] The average circularity of toner particles is determined by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)]. Specifically, it is a value measured by the following method. First, the toner particles to be measured are collected by suction, a flattened flow is formed, and a strobe flash is instantaneously activated to capture a still image of the particles. This particle image is then analyzed using a flow-type particle image analyzer (Paasche analyzer PAS, manufactured by Hosokawa Micron Corporation). The number of samples used to determine the average circularity is 10,000. If the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0238] -External additives- As an external additive, silicone oil surface-modified silica particles are used.

[0239] --Silicone oil surface-modified silica particles-- Silicone oil surface-modified silica particles are silica particles such as fumed silica and colloidal silica whose surfaces have been modified with silicone oil. Silicone oil adheres to the surface of the silicone oil surface-modified silica particles.

[0240] Examples of silicone oils for surface-modifying silica particles include dialkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, and dipropylpolysiloxane; phenyl-modified polysiloxanes in which part of the side chain of a dialkylpolysiloxane is substituted with a phenyl group; and fluoroalkyl-modified polysiloxanes in which part of the side chain of a dialkylpolysiloxane is substituted with a fluoroalkyl group. One type of silicone oil may be used alone, or two or more types may be used in combination.

[0241] Treatment methods for surface-modifying silica particles with silicone oil include: a spray method in which silicone oil or a solution containing silicone oil is sprayed onto silica particles in the gas phase; an immersion method in which silica particles are immersed in silicone oil or a solution containing silicone oil; and a mixing method in which silicone oil or a solution containing silicone oil and silica particles are mixed using a mixer.

[0242] The amount of oil adhering to the silicone oil surface-modified silica particles is preferably 1% to 30% by mass, more preferably 3% to 20% by mass, even more preferably 5% to 15% by mass, and particularly preferably 8% to 12% by mass, relative to the total mass of the silica particles (untreated silica particles). When the amount of oil adhering to the image is within the above range, the peak intensity ratio (A / B) is more easily controlled to stay within that range. As a result, streaky image defects and fogging are more easily suppressed.

[0243] The amount of free oil in the silicone oil surface-modified silica particles is preferably 3% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and even more preferably 8% by mass or more and 15% by mass or less. When the amount of free oil is within the above range, the peak intensity ratio (A / B) is more easily controlled to stay within that range. As a result, streaky image defects and fogging are more easily suppressed.

[0244] Here, the amount of free oil is the ratio of the amount of free oil to the total amount of silicone oil surface-modified silica particles.

[0245] The amount of oil adhering to the surface and the amount of free oil are values ​​measured by the following method. Proton NMR measurements are performed on silicone oil-surface-modified silica particles using a JEOL AL-400 (magnetic field 9.4T (H nucleus 400MHz)). The sample, deuterated chloroform solvent, and TMS as a reference material are packed into a zirconia sample tube (5mm diameter). With this sample tube set up, measurements are performed, for example, at a frequency of Δ87kHz / 400MHz (=Δ20ppm), a measurement temperature of 25℃, 16 integration cycles, and a resolution of 0.24Hz (32000 points). The amount of free oil is then calculated from the peak intensity derived from the free oil using a calibration curve. For example, if dimethyl silicone oil is used as the oil, NMR measurements are performed on untreated silica particles and dimethyl silicone oil (similarly varying the amounts in about 5 levels) to create a calibration curve between the amount of oil released and the NMR peak intensity. Then, the amount of released oil is calculated using the calibration curve. Then, the amount of oil adhering to the untreated silica particles and free oil is calculated.

[0246] To increase the amount of free oil in silicone oil-treated silica particles, for example, the oil treatment can be performed multiple times. To reduce the amount of free oil in small-diameter oil-treated silica particles, for example, the process of immersion in a solvent followed by drying can be repeatedly performed.

[0247] From the viewpoint of suppressing streaky image defects and fogging, the number-average particle size of the silicone oil surface-modified silica particles is preferably 10 nm to 50 nm, more preferably 20 nm to 45 nm, and even more preferably 30 nm to 40 nm.

[0248] The amount of silicone oil surface-modified silica particles added is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.3 parts by mass or more and 2.5 parts by mass or less, and even more preferably 0.5 parts by mass or more and 2.0 parts by mass or less, per 100 parts by mass of toner particles. When the amount of external additive is within the above range, the peak intensity ratio (A / B) is more easily controlled within that range. As a result, streaky image defects and fogging are more easily suppressed.

[0249] --Compatible silica particles- Silica particles that can be used in combination with silicone oil-surface-modified silica particles may also be silica particles whose surfaces have been modified with oils other than silicone oil (for example, paraffin oil, fluorine-based oil, etc.). However, silica particles that have not been surface-modified with any oil are preferred for use in combination. In other words, silica particles that do not have oil adhering to their surface are preferred for use in combination.

[0250] Silica particles without oil adhering to their surface have lower cohesiveness compared to silicone oil-surface-modified silica particles. Therefore, they are less likely to be incorporated into the external additive dam or to easily detach from it, allowing them to slip through the blade nip in small amounts, thus reducing friction between the cleaning blade and the image holder. This is presumed to suppress damage to the cleaning blade, prevent toner particles or parts of the aggregated external additive dam from slipping through the blade nip, and suppress the occurrence of colored or white streaks extending in the direction of transport of the recording medium.

[0251] The silica particles that can be used in combination are preferably silica particles whose surfaces have been hydrophobized with a hydrophobic agent other than oil. Examples of hydrophobic agents for silica particles include silane compounds such as hexamethyldisilazane, diethoxydimethylsilane, dimethoxydiphenylsilane, and dimethyldichlorosilane.

[0252] The number-average particle size of the silica particles that can be used in combination is preferably between 50 nm and 200 nm. If the number-average particle size is 50 nm or more, it is easier for the lubricant to reduce friction between the cleaning blade and the photoreceptor to be exerted, and if the number-average particle size is 200 nm or less, it is less likely to scratch the surface of the image holder. From the above viewpoint, the number-average particle size of the silica particles that can be used in combination is more preferably 80 nm to 200 nm, and even more preferably 90 nm to 150 nm.

[0253] The shape factor SF2 of the silica particles that can be used in combination is preferably 100 to 125, more preferably 100 to 120, and even more preferably 100 to 110. When the shape factor SF2 is within this range, the lubricant effect that reduces friction between the cleaning blade and the photoreceptor is easily exerted.

[0254] The amount of silica particles that can be added in combination is preferably 1.0 part by mass or more and 3.5 parts by mass or less, more preferably 1.5 parts by mass or more and 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or more and 2.5 parts by mass or less, per 100 parts by mass of toner particles.

[0255] Here, the number-average particle size of silica particles is the 50% diameter (D50p) in the cumulative frequency of the equivalent spherical diameter obtained by image analysis of 100 primary silica particles observed with a scanning electron microscope (SEM) when silica particles are added to toner particles.

[0256] The silica particle shape factor SF2 is the average value calculated using the following formula from the perimeter and projected area obtained by image analysis of 100 primary silica particles observed by SEM when silica particles are added to toner particles. Formula: SF2={PM 2 / (4πA)} × 100 In the formula, PM is the perimeter of the silica particle, and A is the projected area of ​​the silica particle.

[0257] --Other external additives-- The toner particles may contain external additives other than silicone oil surface-modified silica particles and silica particles that can be used in combination. However, in this embodiment, it is preferable that the toner particles contain substantially only silicone oil surface-modified silica particles, or only silicone oil surface-modified silica particles and silica particles that can be used in combination.

[0258] Other external additives include, for example, TiO2, Al2O3, SrTiO3, CaTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2). n Examples include Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0259] The surface of the inorganic particles used as an external additive should preferably be hydrophobic. Hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic agent. The hydrophobic agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of hydrophobic treatment agent is typically, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

[0260] Other external additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), and cleaning lubricants (for example, metal salts of higher fatty acids represented by zinc stearate, and particles of higher alcohols).

[0261] (Toner manufacturing method) Next, a description of the toner manufacturing method according to this embodiment will be given. The toner according to this embodiment is obtained by manufacturing toner particles and then adding an external additive to the toner particles.

[0262] Toner particles may be manufactured by either a dry process (e.g., kneading and grinding method) or a wet process (e.g., agglomeration, suspension polymerization, dissolution and suspension method). There are no particular restrictions on the manufacturing method of toner particles, and any well-known method may be used. Among these methods, obtaining toner particles by the aggregation and coalescence method is preferable.

[0263] (Career) There are no particular restrictions on the carriers, and known carriers can be used. Examples of carriers include coated carriers in which a coating resin is applied to the surface of a core material made of magnetic powder; magnetic powder dispersed carriers in which magnetic powder is dispersed and blended in a matrix resin; and resin-impregnated carriers in which resin is impregnated into porous magnetic powder. Furthermore, magnetic powder dispersed carriers and resin-impregnated carriers may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

[0264] The magnetic powder, coating resin, and matrix resin can be selected from well-known materials.

[0265] In a two-component developer, the mixing ratio (mass ratio) of toner and carrier is preferably toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0266] The configuration of the image forming apparatus described in this embodiment is merely an example, and it goes without saying that its configuration may be modified without departing from the spirit of this embodiment. [Examples]

[0267] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way to these examples. Unless otherwise specified, "%" and "parts" are based on mass.

[0268] <Preparation of Developer (1)~(4)> For the black toner of the black developer used in the image forming apparatus (Apeos C2360, manufactured by Fujifilm Business Innovation Co., Ltd.), a mixture of silicone oil-surface-modified silica particles with the quantities and characteristics shown in Table 1 was prepared as an external additive.

[0269] <Preparation of the electrostatic rollers (1) to (7)> -Formation of a conductive elastic layer- • Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber (GECHRON3106, manufactured by Nippon Zeon Co., Ltd.): 100 units • Carbon black (Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.): 25 parts • Ketjenblack EC (manufactured by Lion Specialty Chemicals Co., Ltd.): 8 parts • Ion conductive agent (lithium perchlorate): 1 part Sulfur (200 mesh, manufactured by Tsurumi Chemical Industry Co., Ltd.): 1 part • Vulcanization accelerator (Noxellar DM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.): 2 parts • Vulcanization accelerator (Noxellar TT, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.): 0.5 parts The above materials were kneaded in an open roll to obtain an elastic layer-forming composition. The outer surface of a support made of SUS416, with a diameter of 9 mm and a total length of 370 mm, was coated with the elastic layer-forming composition to a thickness of 1.5 mm, placed in a cylindrical mold with an inner diameter of 12.0 mm, and vulcanized at 170°C for 30 minutes. After being removed from the mold, the outer surface of the conductive elastic layer was polished to obtain an elastic roll. -Formation of the surface layer- • Resin: N-methoxymethylated nylon (product name F30K, manufactured by Nagase ChemteX Co., Ltd.) 100 parts by mass • Resin: Polyvinyl butyral (PVB, product name Esrec BL-1, manufactured by Sekisui Chemical Co., Ltd.): 10 parts by mass Particle A: Carbon black (product name: MONAHRCH1000, manufactured by Cabot): 15 parts by mass Particle B: Polyamide particles (Polyamide 12, manufactured by Arkema): 10 parts by mass • Additive: Dimethylpolysiloxane (BYK-307, manufactured by Altana): 1 part by mass • Methanol: 500 parts by mass • 1-Propanol: 240 parts by mass The above materials were dispersed using a bead mill. Under conditions of 30°C, 40% RH humidity, and an airflow of 2.0 m / sec at a distance of 3 cm from the outer surface of the elastic roll, the resulting dispersion was immersed and coated onto the outer surface of the elastic roll. The mixture was then heated and dried at 130°C for 20 minutes to form a surface layer with a thickness of 10 μm. This yielded a charged roll (1).

[0270] (Fabrication of the electrostatic roll (2)) A charged roll (2) was obtained in the same manner as charged roll (1), except that the surface layer dispersion was immersed and coated onto the outer surface of the elastic roll under conditions of 28°C and 40% RH.

[0271] (Fabrication of the electrostatic roll (3)) A charged roll (3) was obtained in the same manner as charged roll (1), except that the dispersion for the surface layer was immersed and applied to the outer surface of the elastic roll under conditions of a temperature of 24°C, a humidity of 40% RH, and an air velocity of 0.7 m / sec at a distance of 3 cm from the outer surface of the elastic roll.

[0272] (Fabrication of the electrostatic roll (4)) A charged roll (4) was obtained in the same manner as charged roll (1), except that the surface layer dispersion was immersed and applied to the outer surface of the elastic roll under conditions of a temperature of 22°C, a humidity of 50% RH, and an air velocity of 0.1 m / sec at a distance of 3 cm from the outer surface of the elastic roll.

[0273] (Fabrication of the electrostatic roll (5)) A charged roll (5) was obtained in the same manner as charged roll (1), except that the surface layer dispersion was immersed and applied to the outer surface of the elastic roll under conditions of a temperature of 17°C, a humidity of 50% RH, and an air velocity of 0.1 m / sec at a distance of 3 cm from the outer surface of the elastic roll.

[0274] (Fabrication of the electrostatic roll (6)) A charging roll (6) was obtained in the same manner as the charging roll (4), except that the amount of polyvinyl butyral (product name Esrec BL-1, manufactured by Sekisui Chemical Co., Ltd.), which is the surface layer resin, was changed from 10 parts by mass to 15 parts by mass.

[0275] (Fabrication of the electrostatic roll (7)) A charging roll (7) was obtained in the same manner as the charging roll (5), except that the amount of polyvinyl butyral (product name Esrec BL-1, manufactured by Sekisui Chemical Co., Ltd.), which is the surface layer resin, was changed from 10 parts by mass to 15 parts by mass.

[0276] <Preparation of the electrophotographic photoconductor> (Preparation of the photoreceptor (1)) -Formation of the lower layer- Zinc oxide (average particle size: 70 nm, manufactured by Teika Corporation, specific surface area: 15 m²) 2 100 parts by mass of (g) was mixed with 500 parts by mass of tetrahydrofuran and stirred. 1.25 parts by mass of KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a silane coupling agent, and the mixture was stirred for 2 hours. Subsequently, the tetrahydrofuran was removed by vacuum distillation, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide particles with a silane coupling agent surface treatment. 60 parts by mass of surface-treated zinc oxide particles, 0.6 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumijule 3173, manufactured by Sumitomo Bayern Urethanes) as a curing agent, and 15 parts by mass of butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 85 parts by mass of methyl ethyl ketone. 38 parts by mass of this solution was mixed with 25 parts by mass of methyl ethyl ketone, and the mixture was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill to obtain a dispersion. To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospar 145, manufactured by GE Toshiba Silicone Co., Ltd.) were added to obtain a coating solution for the undercoat. This coating solution was applied to a 30 mm diameter aluminum substrate by immersion coating, and dried and cured at 180°C for 40 minutes to obtain a 25 μm thick undercoat layer.

[0277] -Formation of a charge generation layer- Next, as a charge generating material, a mixture consisting of 15 parts by mass of chlorogallium phthalocyanine crystal having strong diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.4°, 16.6°, 25.5°, and 28.3° with respect to CuKα characteristic X-rays, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Union Carbide Japan Co., Ltd.), and 300 parts by mass of n-butyl alcohol was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill to obtain a coating solution for the charge generating layer. This charge generation layer coating solution was applied to the undercoat layer by immersion, and dried at 120°C for 5 minutes to obtain a charge generation layer with a thickness of 0.2 μm.

[0278] -Formation of a charge transport layer- Next, 42 parts by mass of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine and 58 parts by mass of bisphenol Z polycarbonate resin (TS3050: viscosity-average molecular weight 50,000: manufactured by Teijin Chemicals) were thoroughly dissolved and mixed in 280 parts by mass of tetrohydrofuran and 120 parts by mass of toluene to obtain a coating solution for the charge transport layer. This charge transport layer coating solution was immersed and applied onto the aluminum support, which had a charge generation layer formed on top of it, and dried at 135°C for 40 minutes to form a charge transport layer with a thickness of 20 μm.

[0279] -Formation of protective layer A- A protective coating solution was prepared by dissolving 100 parts by mass of the compound (acrylic resin) of the following structural formula (1) in 200 parts by mass of ethanol, and then adding 0.01 parts by mass of a thermal polymerization initiator (Otazo-15, manufactured by Otsuka Chemical Co., Ltd.). The obtained protective coating solution was applied to the aluminum substrate, which had a charge transport layer formed on it, by immersion, and then heated and dried at 150°C for 40 minutes to form a protective layer A with a thickness of 6 μm. [ka]

[0280] After the above steps, a photoreceptor (1) was obtained.

[0281] (Preparation of photoreceptor (2)) A photoreceptor (2) was obtained in the same manner as photoreceptor (1), except that protective layer B was formed in place of protective layer A. -Formation of protective layer B- 45 parts by mass of the compound with the following structural formula (B1), 52 parts by mass of the compound with the following structural formula (B2), and 2 parts by mass of methylated melamine resin (Nicalac MW-30HM, manufactured by Sanwa Chemical Co., Ltd.) were dissolved in 50 parts by mass of isopropyl alcohol and 50 parts by mass of 2-butanol. To this solution, 0.1 parts by mass of dimethylpolysiloxane (Granol 450, manufactured by Kyoeisha Chemical Co., Ltd.) and 0.01 parts by mass of NACUR E2500 (manufactured by King Industry Co., Ltd.) were added to prepare a coating solution for forming a protective layer. The obtained protective coating solution was applied to the aluminum substrate, which had a charge transport layer formed on it, by immersion, and then heated and dried at 150°C for 40 minutes to form a protective layer with a thickness of 6 μm.

[0282] (Preparation of the photoreceptor (3)) A photoreceptor (3) was obtained in the same manner as photoreceptor (1), except that protective layer C was formed in place of protective layer A. -Formation of protective layer C- 45 parts by mass of the compound with structural formula (B1) below, 52 parts by mass of the compound with structural formula (B2) below, and 2 parts by mass of methylated benzoguanamine resin (BL-60, manufactured by Sanwa Chemical Co., Ltd.) were dissolved in 50 parts by mass of isopropyl alcohol and 50 parts by mass of 2-butanol. To this solution, 0.1 parts by mass of dimethylpolysiloxane (Granol 450, manufactured by Kyoeisha Chemical Co., Ltd.) and 0.01 parts by mass of NACUR E2500 (manufactured by King Industries Co., Ltd.) were added to prepare a coating solution for forming a protective layer. The obtained protective coating solution was applied to the aluminum substrate, which had a charge transport layer formed on it, by immersion, and then heated and dried at 150°C for 40 minutes to form a protective layer with a thickness of 6 μm.

[0283] [ka]

[0284] (Preparation of the photoreceptor (4)) A photoreceptor (3) was obtained in the same manner as photoreceptor (1), except that protective layer D was formed in place of protective layer A. -Formation of protective layer D- 25 parts by mass of the compound of structural formula (B1) above, 40 parts by mass of the compound of structural formula (B3) below, 10 parts by mass of phenol resin (PL-2243, Gun-ei Chemical Industry), 0.1 parts by mass of methylphenylpolysiloxane, and 0.1 parts by mass of zinc phenolsulfonate were dissolved in 150 parts by mass of isopropanol and 50 parts by mass of methyl ethyl ketone to obtain a coating solution for forming a protective layer. The obtained protective layer coating solution was applied to the aluminum substrate, which had a charge transport layer formed on it, by immersion, and a protective layer with a thickness of 5 μm was formed by heating and drying at 140°C for 40 minutes. [ka]

[0285] <Examples 1-21, Comparative Examples 1-2> The prepared developer, charging roll, and photoreceptor were mounted in the combinations shown in Table 2 onto the black image forming unit for the image forming apparatus (Apeos C2360, manufactured by Fujifilm Business Innovation Co., Ltd.). Furthermore, the contact width (indicated as "roll contact width" in the table) in the direction of rotation of the photoreceptor at the contact point between the photoreceptor and the charging roll was set to the width shown in Table 1. The obtained image forming apparatus was designated as the "image forming apparatus for each example." The following measurements and evaluations were then performed.

[0286] <Measurement> As described above, the following items were measured. When the silicone oil and silica particles adhering to the surface of the charging roll were measured using the total internal reflection method with an infrared spectrophotometer, the peak intensity A, which originates from the Si-C expansion of the silicone oil, was measured. When the silicone oil and silica particles adhering to the surface of the charged roll were measured using the total internal reflection method with an infrared spectrophotometer, the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles was observed.

[0287] <Rating> (Linear image defects) Under conditions of 28°C and 85% RH, 100,000 images of black halftones with an image density of 30% were printed. Then, under conditions of 10°C and 15% RH, blank images with an image density of 0% were printed, and streaky image defects were evaluated. 1+: No streaky image defects in image quality. 1: Very minor streaky image defects (1-2 streaks) occurred, no problem. 2: Linear image defects occurred (2-5 lines), problematic. 3: Streaky image defects occur across the entire image (5 or more streaks), problematic.

[0288] (Overlap evaluation) Under conditions of 28°C room temperature and 85% RH humidity, 100,000 images of a black halftone with 30% image density were printed. Then, under conditions of 10°C room temperature and 15% RH humidity, a blank image with 0% image density was printed. The reflectance density D of the printed area of ​​the printed images was evaluated for fogging using an X-Rite 404A densitometer. The haze evaluation was performed by assessing the density difference between the unprinted paper and the central part of the printed blank image. A density difference of 0.03 or more was considered to indicate significant haze and therefore problematic. 1+: No overlap occurred 1: Concentration difference of 0.01 or less (very slight fogging occurs) 2: Concentration difference greater than 0.01 and less than 0.03 (flash occurs, no problem) 3: Concentration difference of 0.03 or more (flash occurs, problematic)

[0289] (Evaluation of concentration unevenness) The following concentration variation evaluations were performed under conditions of room temperature (10°C) and humidity (15%RH). An image with a 30% black halftone was output, and the reflectance density D of the printed area of ​​the output image was evaluated for density unevenness using an X-Rite 404A densitometer. Density unevenness was evaluated by assessing the maximum density difference △D at four points at the edges of the image and one point in the center. If the maximum density difference △D exceeded 0.024, density unevenness was considered significant and problematic. 1+: No unevenness in concentration occurred. 1: △D is less than 0.015 2: △D is between 0.015 and 0.024 3: △D exceeds 0.024

[0290] [Table 1]

[0291] [Table 2]

[0292] From the results above, it can be seen that this embodiment can suppress both streaky image defects and fogging compared to the comparative example.

[0293] This embodiment includes the following aspects. (((1))) Electrophotographic photoreceptor, A charging device having a charging member that contacts the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, A transfer device for transferring a toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium, Equipped with, An image forming apparatus in which, when the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A originating from the Si-C stretching of the silicone oil and the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less. (((2))) The image forming apparatus according to (((1))), wherein the peak intensity ratio (A / B) is 0.21 or less. (((3))) The image forming apparatus according to (((1))) or (((2))), wherein the contact width of the contact portion between the electrophotographic photoreceptor and the charging member in the rotational direction of the electrophotographic photoreceptor is 0.31 mm or more and 0.58 mm or less. (((4))) The image forming apparatus according to (((3))), wherein the contact width is 0.35 mm or more and 0.56 mm or less. (((5))) The image forming apparatus according to any one of (((1))) to (((4))), wherein the surface roughness Rz of the charged member is 2.5 μm or more and 6.8 μm or less. (((6))) The image forming apparatus according to (((5))), wherein the surface roughness Rz of the charging member is 3.2 μm or more and 5.9 μm or less. (((7))) The electrophotographic photoreceptor has a conductive substrate, a photosensitive layer, and a protective layer in this order. The image forming apparatus according to any one of (((1))) to (((6))), wherein the protective layer is a cured film made of a cured product of a composition comprising a curing agent and a charge transport material containing reactive groups that react with the curing agent. (((8))) The curing agent is at least one compound selected from the group consisting of compounds having a guanamine structure and compounds having a melamine structure. The image forming apparatus according to ((7))) wherein the reactive group-containing charge transport material is a charge transport material having at least one group selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH. (((9))) The curing agent is a curable phenolic resin, The image forming apparatus according to ((7))), wherein the reactive group-containing charge transport material is a charge transport material having at least one group selected from the group consisting of hydroxyalkyl groups, hydroxyalkoxy groups, and hydroxyphenyl groups. (((10))) A charging device having a charging member that contacts the surface of an electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, Equipped with, When the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A originating from the Si-C stretching of the silicone oil and the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less. A process cartridge that is attached to and detached from an image forming apparatus.

[0294] The effects of the above embodiment are as follows: According to the invention of (((1))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.25. According to the invention of (((2))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.21. According to the invention of (((3))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the rotational direction of the electrophotographic photoreceptor is less than 0.31 mm or greater than 0.58 mm. According to the invention of (((4))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the rotational direction of the electrophotographic photoreceptor is less than 0.35 mm or greater than 0.56 mm. According to the invention of (((5))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the surface roughness Rz of the charged member is less than 2.5 μm or greater than 6.8 μm. According to the invention of (((6))), an image forming apparatus is provided that suppresses fogging along with streaky image defects compared to the case where the surface roughness Rz of the charged member is less than 3.2 μm or greater than 5.9 μm.

[0295] According to the inventions of (((7))), (((8))), or (((9))), an image forming apparatus is provided that suppresses fogging along with streaky image defects, even when a photoreceptor has a protective layer made of a cured film, compared to the case where the peak intensity ratio (A / B) exceeds 0.25. According to the invention of (((10))), a process cartridge is provided that suppresses fogging along with streaky image defects compared to the case where the peak intensity ratio (A / B) exceeds 0.25. [Explanation of symbols]

[0296] 10 Image forming apparatus 12 Photoreceptor 14 Charged members 15. Charging device 16 Electrostatic image forming device 18. Developing device 20 Transfer Member 22 Cleaning device 22A Cleaning Blade 24 Static eliminator 26 Fixing device 30A recording medium 31 Transfer device 36 Control device 101 Sublayer 102 Charge generation layer 103 Charge transport layer 104 Conductive substrate 105 Photosensitive layer

Claims

1. Electrophotographic photoreceptor, A charging device having a charging member that contacts the surface of the electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, A transfer device for transferring a toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium, Equipped with, An image forming apparatus in which, when the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A originating from the Si-C stretching of the silicone oil and the peak intensity B originating from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less.

2. The image forming apparatus according to claim 1, wherein the peak intensity ratio (A / B) is 0.21 or less.

3. The image forming apparatus according to claim 1, wherein the contact width of the contact portion between the electrophotographic photoreceptor and the charged member in the rotational direction of the electrophotographic photoreceptor is 0.31 mm or more and 0.58 mm or less.

4. The image forming apparatus according to claim 3, wherein the contact width is 0.35 mm or more and 0.56 mm or less.

5. The image forming apparatus according to claim 1, wherein the surface roughness Rz of the charging member is 2.5 μm or more and 6.8 μm or less.

6. The image forming apparatus according to claim 5, wherein the surface roughness Rz of the charging member is 3.2 μm or more and 5.9 μm or less.

7. The electrophotographic photoreceptor has a conductive substrate, a photosensitive layer, and a protective layer in this order. The image forming apparatus according to claim 1, wherein the protective layer is a cured film made of a cured product of a composition comprising a curing agent and a reactive group-containing charge transport material that reacts with the curing agent.

8. The curing agent is at least one compound selected from the group consisting of compounds having a guanamine structure and compounds having a melamine structure. The aforementioned reactive group-containing charge transport material is -OH, -OCH ３ , -NH ２ The image forming apparatus according to claim 7, which is a charge transport material having at least one group selected from the group consisting of -SH and -COOH.

9. The curing agent is a curable phenolic resin, The image forming apparatus according to claim 7, wherein the reactive group-containing charge transport material is a charge transport material having at least one group selected from the group consisting of hydroxyalkyl groups, hydroxyalkoxy groups, and hydroxyphenyl groups.

10. A charging device having a charging member that contacts the surface of an electrophotographic photoreceptor and charges the surface of the electrophotographic photoreceptor, A static charge image forming apparatus for forming a static charge image on the surface of the charged electrophotographic photoreceptor, A developing apparatus that contains an electrostatic image developer having toner particles and silicone oil surface-modified silica particles as an external additive, and supplies the electrostatic image developer to develop the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image, Equipped with, When the silicone oil and silica particles adhering to the surface of the charged member are measured by total internal reflection using an infrared spectrophotometer, the peak intensity ratio (A / B) of the peak intensity A derived from the Si-C stretching of the silicone oil and the peak intensity B derived from the Si-O-Si antisymmetric stretching of the silica particles is 0.25 or less. A process cartridge that is attached to and detached from an image forming apparatus.

Images