JP2014145929A - Process cartridge and electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge and an electrophotographic apparatus that further restrict occurrences of image defects such as white stripe and irregularities.SOLUTION: The surface layer of an electrophotographic photoreceptor contains a siloxane compound. An elastic layer 2 of a charging member contains a polymer having a unit derived from alkylene oxide, and conductive particles. The surface of the elastic layer of a charging member has an exposure part in which conductive particles are exposed from the elastic layer. The surface of the elastic layer of the charging member containing the conductive-particle exposure part is covered with a surface layer 3 of the charging member. The surface layer of the charging member contains binding resin and resin particles 102 dispersed in the binding resin. The surface of the surface layer of the charging member has a plurality of projections derived from the resin particles. When the resin particles in the surface layer of the charging member are orthogonally projected on the surface of the elastic layer of the charging member, portions of the charging member other than the resin-particle projection parts of in the surface of the elastic layer overlap the conductive-particle exposure part.

Description

  The present invention relates to a process cartridge and an electrophotographic image forming apparatus (hereinafter referred to as “electrophotographic apparatus”).

  In recent years, as a charging method for an electrophotographic photosensitive member, a method in which a voltage is applied to a charging member (conductive roller) that contacts the electrophotographic photosensitive member to charge the electrophotographic photosensitive member, so-called contact charging method, has become mainstream. ing.

  On the other hand, with the demand for higher image quality, electrophotographic photoreceptors have a surface layer made of a resin having a silicone oil or a siloxane structure (hereinafter also referred to as “siloxane compound”) for improving the leveling function and surface properties of the coating film. It is made to contain.

  Patent Document 1 discloses a technique in which a polycarbonate resin having a siloxane structure at the main chain and terminal is contained as a resin having a siloxane structure in the surface layer of an electrophotographic photosensitive member.

  In Patent Document 2, a resin having a siloxane structure is contained in the surface layer of the electrophotographic photosensitive member, and the content of free silicone typified by the silicone oil is 100 ppm or less, and A technique that achieves both improvement in surface properties and suppression of image defects such as white stripes and black stripes is disclosed.

JP 2008-175980 A JP 2012-123379 A

  However, when an image is formed using an electrophotographic photosensitive member having a surface layer containing a siloxane compound, sufficient image quality cannot be obtained if the discharge amount in the charging step (discharge amount from the charging member) is increased. In some cases, there was room for improvement.

  Therefore, as a result of intensive studies by the present inventors, it was found that the siloxane compound contained in the surface layer of the electrophotographic photosensitive member is likely to have a low molecular weight by increasing the discharge amount in the charging step. . When the low molecular weight siloxane compound oozes out from the surface of the electrophotographic photosensitive member and adheres to the surface of the charging member, uneven discharge (discharge unevenness) is likely to occur in the discharge from the charging member. It has become clear that the image defects are likely to occur.

  An object of the present invention is to further suppress the occurrence of image defects such as white stripes and unevenness when an electrophotographic photosensitive member containing a siloxane compound in the surface layer and a charging member in contact with the electrophotographic photosensitive member are used in combination. It is an object of the present invention to provide a process cartridge and an electrophotographic apparatus that can handle the above.

  The above object is achieved by the present invention described below.

In the process cartridge that integrally supports the electrophotographic photosensitive member and the charging member and is detachable from the main body of the electrophotographic apparatus,
The surface layer of the electrophotographic photoreceptor contains a siloxane compound,
The charging member has a conductive substrate, an elastic layer formed on the conductive substrate, and a surface layer formed on the elastic layer;
The elastic layer of the charging member contains a polymer having a unit derived from an alkylene oxide, and at least one conductive particle selected from the group consisting of graphite particles and graphitized particles,
The surface of the elastic layer of the charging member has an exposed portion where the conductive particles are exposed from the elastic layer;
The surface of the elastic layer of the charging member including the exposed portion of the conductive particles is covered with the surface layer of the charging member;
The surface layer of the charging member contains a binder resin and resin particles dispersed in the binder resin;
The surface of the surface layer of the charging member has a plurality of convex portions derived from the resin particles,
When the resin particles in the surface layer of the charging member are orthographically projected onto the surface of the elastic layer of the charging member, a portion other than the projected portion of the resin particles on the surface of the elastic layer of the charging member is The present invention relates to a process cartridge that overlaps with the exposed portion of the conductive particles.

The present invention also provides:
In an electrophotographic apparatus having an electrophotographic photosensitive member and a charging member,
The surface layer of the electrophotographic photoreceptor contains a siloxane compound,
The charging member has a conductive substrate, an elastic layer formed on the conductive substrate, and a surface layer formed on the elastic layer;
The elastic layer of the charging member contains a polymer having a unit derived from an alkylene oxide, and at least one conductive particle selected from the group consisting of graphite particles and graphitized particles,
The surface of the elastic layer of the charging member has an exposed portion where the conductive particles are exposed from the elastic layer;
The surface of the elastic layer of the charging member including the exposed portion of the conductive particles is covered with the surface layer of the charging member;
The surface layer of the charging member contains a binder resin and resin particles dispersed in the binder resin;
The surface of the surface layer of the charging member has a plurality of convex portions derived from the resin particles,
When the resin particles in the surface layer of the charging member are orthographically projected onto the surface of the elastic layer of the charging member, a portion other than the projected portion of the resin particles on the surface of the elastic layer of the charging member is The present invention relates to an electrophotographic apparatus characterized by overlapping with the exposed portion of the conductive particles.

  According to the present invention, when an electrophotographic photoreceptor containing a siloxane compound in the surface layer and a charging member in contact with the electrophotographic photoreceptor are used in combination, the occurrence of image defects such as white stripes and unevenness is further suppressed. A process cartridge and an electrophotographic apparatus capable of performing the same can be provided.

Sectional drawing of a charging member (roller shape) is shown. The fragmentary sectional view of the elastic layer and surface layer of a charging member is shown. It is the schematic which shows the positional relationship of the projection part of a resin particle when the resin particle in a surface layer is orthographically projected on the surface of an elastic layer, and the exposed part which the electroconductive particle is exposed. 1 is a schematic cross-sectional view of an example of an electrophotographic apparatus. It is a cross-sectional schematic diagram of an example of a process cartridge. FIG. 4 is a schematic diagram illustrating a contact state between a charging member (roller shape) and an electrophotographic photosensitive member. It is a figure which shows an example of the layer structure of an electrophotographic photoreceptor. It is the schematic which shows the flow of solvent osmosis | permeation in the surface of an elastic layer after apply | coating the coating liquid for surface layers at the time of manufacturing a charging member.

(Charging member)
FIG. 1 (1 a) shows an example of a cross section of the charging member. The charging member includes a conductive substrate 1, an elastic layer (conductive elastic layer) 2 covering the peripheral surface, and a surface layer ( Conductive surface layer) 3. As shown in FIG. 1 (1b), the charging member may have a configuration in which the elastic layer 2 has two or more layers (FIG. 1 (1b) has a first elastic layer 21 and a second elastic layer 22).

  Note that the conductive substrate 1 and the layer sequentially stacked on the conductive substrate 1 (for example, the elastic layer 2 shown in FIG. 1A and the first elastic layer 21 shown in FIG. 1B are formed of a conductive adhesive. A known conductive agent can be used as the adhesive for making the conductive, and the first elastic layer 21 and the second elastic layer 21 shown in FIG. The elastic layers 22 may also be bonded via a conductive adhesive.

  FIG. 2 is an enlarged partial sectional view of the elastic layer and the surface layer of the charging member. The elastic layer 2 contains a polymer having a unit derived from an alkylene oxide and conductive particles (101a, 101b, and 101c), and exposed portions where the conductive particles are exposed from the elastic layer 2 on the surface thereof. (For example, 103). The surface of the elastic layer including the exposed portion 103 of the conductive particles is covered with the surface layer 3. The surface layer 3 includes a binder resin and resin particles 102 and has a plurality of convex portions derived from the resin particles on the surface thereof.

  FIG. 3 shows a schematic view when the resin particles in the surface layer of the charging member are orthographically projected onto the surface of the elastic layer. An exposed portion 103 where the conductive particles are exposed from the elastic layer is present on the surface 108 of the elastic layer. Here, the projection part when the resin particles in the surface layer are orthographically projected onto the surface of the elastic layer is a projection view indicated by 107, for example. One feature of the present invention is that a portion (for example, a portion other than 106) of the resin particles overlaps with an exposed portion (for example, 105) of the conductive particles.

  The present inventors presume the reason for suppressing the occurrence of image defects such as white stripes and unevenness by using the electrophotographic photosensitive member and the charging member according to the present invention.

  As the amount of discharge in the charging process increases, the siloxane compound in the surface layer of the electrophotographic photoreceptor is considered to have a low molecular weight. The stability of the discharge from the exposed portion of the conductive particles (hereinafter, the conductive particles are also referred to as graphite particles and / or graphitized particles) decreases due to the low molecular weight siloxane compound adhering to the surface of the charging member. It is assumed that image defects such as white stripes and unevenness are likely to occur.

  Regarding the charging member according to the present invention, conductive particles such as graphite particles and graphitized particles, which will be described in detail later, are substances containing carbon atoms that form a layer structure by SP2 covalent bonds, and exhibit high conductivity. And the graphite particle or graphitized particle which has high electroconductivity has the exposed part exposed from the elastic layer, and the surface of the elastic layer containing an exposed part is coat | covered by the surface layer. Since the exposed portion 103 of the conductive particles is present at a position that does not overlap with the convex portion of the surface layer, the exposed portion 103 (eg, 109 in FIG. 3) corresponding to the surface of the charging member is preferentially used. Electric discharge (discharge in the nip) can be generated.

  When the process cartridge of the present invention having the charging member is used in combination with an electrophotographic photosensitive member containing a siloxane compound in the surface layer, the siloxane compound having a reduced molecular weight is the resin of the surface of the charging member. It tends to adhere to convex portions derived from particles. On the other hand, since the low molecular weight siloxane compound is difficult to adhere to the surface of the charging part of the exposed part that is not a convex part, discharge from the exposed part of the graphite particles and graphitized particles causes discharge within the nip. Is considered to be stable. As a result, it is presumed that the occurrence of image defects such as white stripes and unevenness is suppressed even when repeated image formation is performed.

  It should be noted that the portion of the exposed portion corresponding to the surface of the charging member (for example, 109) has a discharge strength (inside the nip) when the surface including the graphite particles or the exposed portion of the graphite particles is covered with the surface layer of the charging member. It is easy to maintain the discharge intensity) more stably.

(Charging member)
(Conductive substrate)
The conductive substrate used in the charging member according to the present invention is conductive and has a function of supporting a surface layer and an elastic layer formed thereon. Examples of the material include metals such as iron, copper, stainless steel, aluminum, and nickel, and alloys thereof. In addition, for the purpose of imparting scratch resistance to these surfaces, surface treatment such as plating treatment may be performed within a range not impairing conductivity. Furthermore, as the conductive substrate, a conductive substrate obtained by coating the surface of a resin substrate with metal and imparting conductivity to the surface, or a conductive substrate manufactured from a conductive resin composition can be used. is there.

(Elastic layer)
The elastic layer 2 is provided to ensure a sufficient contact width (contact nip width) between the charging member and the electrophotographic photosensitive member. The elastic layer 2 has conductivity, and can contain a polymer having a unit derived from an alkylene oxide, thereby imparting conductivity suitable for the charging member to the elastic layer. The volume resistivity of the elastic layer of the charging member is preferably 10 ² Ω · cm or more and 10 ¹⁰ Ω · cm or less when measured in a temperature 23 ° C. and humidity 50% RH environment.

The elastic layer is a polymer having a unit derived from alkylene oxide, and a polymer having a unit derived from alkylene oxide containing at least one conductive particle selected from the group consisting of graphite particles and graphitized particles. For example, epichlorohydrin rubber, homopolymer of ethylene oxide, copolymer of ethylene oxide and propylene oxide, polyether ester, polyether amide, polyether ester amide, poly (ethylene glycol acrylate), poly (ethylene glycol) methyl ether , Block copolymer of poly (ethylene glycol) and polyethylene, block copolymer of poly (ethylene glycol) and poly (propylene glycol), poly (ethylene glycol) and poly (tetramethylene) Glycol) block copolymers.

  In addition to the polymer having units derived from alkylene oxide, the elastic layer may contain other resins. Examples of the other resin include nitrile rubber (NBR), chloroprene rubber, urethane rubber, silicone rubber, styrene / butadiene / styrene / block copolymer (SBS), styrene / ethylene butylene / styrene / block copolymer (SEBS), and the like. It is done. When these other resins are used, the content is preferably 100% by mass or less based on the polymer having units derived from alkylene oxide.

(Conductive particles)
The elastic layer 2 includes at least one conductive particle selected from the group consisting of graphite particles and graphitized particles. Among the conductive particles, in the Raman spectrum is preferably one peak in the peak intensity half width of 1580 cm ^-1 derived from graphite (.DELTA..nu ₁₅₈₀₎ is 80 cm ^-1 or less, and more preferably not more 60cm ^-1 or less .

  Furthermore, it is more preferable that the spacing between the graphite (002) planes of the graphite particles and graphitized particles is 0.3354 or more and 0.3365 or less. It is known that the plane spacing of the graphite (002) plane of complete graphite particles is 0.3354. And as the value increases from 0.3354, the conductivity of the graphite particles and graphitized particles tends to decrease. That is, graphite particles and graphitized particles having a crystal structure in which hexagonal mesh planes are stacked have high conductivity because π electrons that move like free electrons exist in the hexagonal mesh. As described above, the graphite particles and the graphitized particles have high conductivity when the interval between the graphite (002) planes is 0.3354 or more and 0.3365 or less.

  When the spacing between the graphite surfaces is 0.3354 or more and 0.3365 or less, the graphite particles and the graphitized particles have developed crystal structures in which hexagonal mesh planes are stacked, and have a scaly shape. In this case, the graphite particles and the graphitized particles are easily cleaved in the polishing step, which is the step of exposing the graphite particles and the graphitized particles, which will be described in detail later. For this reason, in the polishing step, the graphite particles and the graphitized particles are less likely to fall off from the elastic layer, and the exposed portion can be formed more stably.

  The cleaving means that in the polishing step, the graphite particles and / or graphitized particles are split at the crystal plane and divided into two or more particles. In such a case, it becomes easy to control the graphite particles and / or the graphitized particles to be exposed on the surface of the elastic layer after the polishing step. On the other hand, the term “dropping” means that in the polishing step, the graphite particles and / or graphitized particles are dropped as one particle from the elastic layer surface without being split as described above. In such a case, it is often difficult to control the graphite particles and / or graphitized particles to be exposed on the surface of the elastic layer.

  As the graphite particles and graphitized particles, either natural graphite or artificial graphite can be used. Natural graphite can be used as the graphite particles, and artificial graphite can be used as the graphitized particles. Natural graphite as graphite particles has high crystallinity, and the plane spacing of the graphite (002) plane is often in the range of 0.3354 to 0.3365. The particle size and shape of the graphite particles can be adjusted by pulverization and classification.

  The interplanar spacing of the graphite (002) plane can be measured by the following method (measuring method 1-1). An X-ray diffraction chart is obtained by measurement under the following conditions using a sample horizontal strong X-ray diffractometer (product (trade name: RINT / TTR-II; manufactured by Rigaku Corporation)), and graphite contained in the elastic layer As for the particles and graphitized particles, first, about 50 mg of graphite particles or graphitized particles are collected from the elastic layer, and an X-ray diffraction chart is obtained using the above-mentioned apparatus.

The peak position of the diffraction line from the graphite (002) plane is obtained from the X-ray diffraction chart, and the spacing between the graphite (002) planes (graphite d (002)) is determined using the Bragg formula represented by the following formula (1). Is calculated. In this invention, it measured with the above-mentioned measuring method.
Formula (1) Graphite d (002) = λ / (2 × sin θ).

<Measurement conditions>
Sample mass: 50 mg
Radiation source: CuKα ray (wavelength λ = 0.15418 nm)
Optical system: Parallel beam optical system Goniometer: Rotor horizontal goniometer (TTR-2)
Tube voltage / current: 50 kV / 300 mA
Measurement method: Continuous method Scan axis: 2θ / θ
Measurement angle: 10 ° to 50 °
Sampling interval: 0.02 °
Scanning speed: 4 ° / min.
Divergent slit: Open Divergent longitudinal slit: 10mm
Scattering slit: Opening Light receiving slit: 1.00 mm.

  Artificial graphite (graphitized particles) can be produced by firing a precursor of graphitized particles. The graphitized particles can control the shape and conductivity of the obtained graphitized particles by selecting the precursor and the firing conditions thereof. That is, the interval between the graphite (002) planes can be adjusted by firing conditions. The shape of the graphitized particles obtained is almost determined by the shape of the precursor. Examples of the precursor that can be used include bulk mesophase pitch, mesocarbon microbeads, phenol resin, phenol resin coated mesophase, and coke coated pitch. The conductivity of the obtained graphitized particles varies depending on the firing conditions, and generally the conductivity obtained as a result of firing at a high temperature for a long time becomes higher. Furthermore, the conductivity of the graphitized particles varies depending on the chemical bond structure of the precursor. Since the ease of change in crystallinity such as non-graphitization and graphitization varies depending on the precursor, the same conductivity is not obtained even if firing under the same conditions. Although the specific manufacturing method of these graphitized particles is demonstrated below, a graphitized particle is not necessarily limited to what is obtained by these manufacturing methods.

Graphitized particles obtained by firing pitch-coated coke and graphitized particles obtained by firing pitch-coated coke and obtained by adding pitch to coke, forming, and then firing. It is done. As the coke, residual oil in petroleum distillation or raw coke obtained by heating coal tar pitch at a temperature of about 500 ° C. and further calcined at a temperature of 1200 ° C. to 1400 ° C. can be used. As the pitch, a pitch obtained as a distillation residue of tar can be used.

  As a method of obtaining graphitized particles using these raw materials, first, coke is pulverized and mixed with pitch. Then, it knead | mixes under a heating of about 150 degreeC, and shape | molds using a molding machine. The molded product is heat-treated at a temperature of 700 ° C. or higher and 1000 ° C. or lower to impart thermal stability. Next, desired graphitized particles are obtained by heat treatment at a temperature of 2600 ° C. or higher and 3000 ° C. or lower. During the heat treatment, the molded product is preferably covered with packing coke in order to prevent oxidation.

-Graphitized particles obtained by calcining bulk mesophase pitch Bulk mesophase pitch is obtained, for example, by extracting β-resin by solvent fractionation from coal tar pitch, etc., and hydrogenating it and performing heavy processing be able to. It can also be obtained by pulverizing after the heavy treatment, and then removing the solvent-soluble component with benzene or toluene. This bulk mesophase pitch preferably has a quinoline soluble content of 95% by mass or more. If it is 95 mass% or more, it is more preferable because the inside of the particles is liable to be liquid-phase carbonized and easily controlled to a shape close to a sphere.

  As a method for obtaining graphitized particles using a bulk mesophase pitch, first, the above bulk mesophase pitch is finely pulverized and heat-treated in air at a temperature of 200 ° C. or higher and 350 ° C. or lower to be lightly oxidized. . By this oxidation treatment, only the surface of the bulk mesophase pitch particles is infusible, and melting and fusion during the heat treatment in the next step are suppressed. The oxidized bulk mesophase pitch particles suitably have an oxygen content of 5% by mass or more and 15% by mass or less. If the oxygen content is 5% by mass or more, it is possible to suppress intensification of fusion between particles during heat treatment. Moreover, if oxygen content is 15 mass% or less, it can oxidize to the inside of particle | grains, can suppress graphitizing with the shape being crushed, and can obtain spherical particle | grains. Desired graphitized particles can be obtained by heat-treating the oxidized bulk mesophase pitch particles at a temperature of 1000 ° C. or higher and 3500 ° C. or lower in an inert gas atmosphere such as nitrogen or argon.

-Graphitized particles obtained by firing mesocarbon microbeads As a method for obtaining mesocarbon microbeads, heat treatment is performed on coal-based heavy oil or petroleum heavy oil at a temperature of 300 ° C or higher and 500 ° C or lower. Condensation produces crude mesocarbon microbeads. After that, the reaction product is treated by filtration, stationary sedimentation, centrifugation, etc. to separate the mesocarbon microbeads, washed with a solvent such as benzene, toluene, xylene, and further dried to obtain mesocarbon. Microbeads are obtained.

  As a method of obtaining graphite particles using these mesocarbon microbeads, firstly, the mesocarbon microbeads that have been dried are first mechanically dispersed with a force that does not cause destruction. It is preferable for obtaining suppression and uniform particle size. The mesocarbon microbeads after the primary dispersion are subjected to primary heat treatment at a temperature of 200 ° C. or higher and 1500 ° C. or lower in an inert gas atmosphere to obtain carbides. It is preferable that the carbide is mechanically dispersed (secondary dispersion treatment) with a force that does not cause destruction in order to suppress aggregation of particles after graphitization and obtain a uniform particle size. The desired graphitized particles are obtained by subjecting the carbide after the secondary dispersion treatment to a secondary heat treatment at a temperature of 1000 ° C. or higher and 3500 ° C. or lower in an inert gas atmosphere.

  The volume average particle size of the conductive particles (graphite particles or graphitized particles) in the elastic layer is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 100 μm or less. By making it within these ranges, it becomes easy to control the positional relationship with the resin particles contained in the surface layer of the charging member.

  The content of conductive particles (graphite particles or graphitized particles) in the elastic layer is preferably 1 part by mass to 100 parts by mass, more preferably 5 parts by mass with respect to 100 parts by mass of the polymer having units derived from alkylene oxide. From 50 parts by mass to 50 parts by mass.

  The conductive particles (graphite particles or graphitized particles) preferably have a scale-like shape. As the scale-like shape, for example, the ratio of major axis / minor axis of conductive particles (graphite particles or graphitized particles) is preferably 1 or more and 5 or less, and preferably 1.2 or more and 2.5 or less. More preferred. By setting it within these ranges, it is possible to more stably form the exposed portion without causing the conductive particles (graphite particles or graphitized particles) to fall off the elastic layer in the polishing step described above. become.

  The volume average particle diameter of the conductive particles (graphite particles or graphitized particles) and the ratio of the major axis / minor axis of the conductive particles (graphite particles or graphitized particles) are as follows. The three-dimensional particle shape of the contained particles is measured (measurement method 1-2).

  As for graphite particles or graphitized particles, and resin particles themselves described later, only primary particles excluding secondary agglomerated particles are focused on a focused ion beam processing observation device (trade name: FB-2000C, Hitachi, Ltd.). And a cross-sectional image is taken. The “three-dimensional particle shape” of the measurement target particle is calculated by combining the cross-sectional images taken for the same particle at intervals of 20 nm. This operation is performed for 100 arbitrary particles.

  In addition, for the particles contained in the elastic layer or the surface layer described later, the region of 500 μm in the circumferential direction extending from the surface layer to the elastic layer over an arbitrary point in the longitudinal direction of 500 μm is formed by 20 nm each. Cut out with a focused ion beam and take a cross-sectional image. And the image which image | photographed the same particle | grains is combined by 20 nm space | interval, and a "three-dimensional particle shape" is calculated. This operation is performed for 10 arbitrary particles photographed, and at the same time, a total of 100 three-dimensional particle shapes are calculated for any 10 points on the surface of the charging member.

  The volume average particle diameters of the graphite particles and graphitized particles are the same as those described in Measurement Method 1-2 for the particles excluding the graphite particles and the graphitized particles exposed from the elastic layer (that is, particles existing in the elastic layer). The “three-dimensional particle shape” is calculated by the method. Let the average value of 100 obtained be a volume average particle diameter (measuring method 1-3).

  The ratio of major axis / minor axis of the graphite particles and graphitized particles is determined by the measurement method 1-2 for the particles excluding the graphite particles and the graphitized particles exposed from the elastic layer (that is, particles existing in the elastic layer). The “three-dimensional particle shape” is calculated by the method described. The maximum diameter / minimum diameter of each particle is measured from this “three-dimensional particle shape”, and the average value of 100 particles is taken as the ratio of long diameter / short diameter (measurement method 1-4).

(Other materials)
The elastic layer 2 may contain an ionic conductive agent or an electronic conductive agent for adjusting the volume resistivity. An ionic conductive agent is preferably used for adjusting the volume resistivity of the elastic layer. Examples of the ionic conductive agent include inorganic ionic substances such as lithium perchlorate, sodium perchlorate, and calcium perchlorate, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyl. Cationic surfactants such as trimethylammonium chloride, trioctylpropylammonium bromide, modified aliphatic dimethylethylammonium ethosulphate, zwitterionic surfactants such as lauryl betaine, stearyl betaine, dimethylalkyl lauryl betaine, tetraethylammonium perchlorate , Tetrabutylammonium perchlorate, trimethyloctadecyl ammonium perchlorate, etc. Grade ammonium salts, and organic lithium salt such as lithium trifluoromethane sulfonate. These can be used alone or in combination of two or more. Among these, it is more preferable to use an ammonium salt.

  The elastic layer 2 may contain additives such as softening oil and plasticizer in order to adjust the hardness of the elastic layer.

[Method of forming elastic layer]
The method for forming the conductive elastic layer will be described below, taking as an example the case of using a polymer having units derived from alkylene oxide.

  First, a coating layer (hereinafter referred to as “preliminary coating layer”) in which the conductive particles (graphite particles and graphitized particles) are dispersed in a polymer having an alkylene oxide-derived unit on a conductive substrate. ). Thereafter, the conductive particles are exposed on the surface of the elastic layer by polishing the surface.

  The preliminary coating layer can be formed by an electrostatic spray coating method, a dipping coating method, a roll coating method, a method of adhering or coating a sheet-shaped or tube-shaped layer formed in a predetermined film thickness, and conducting in a mold. And a method in which the conductive resin composition is disposed on the outer periphery of the conductive substrate and cured. In particular, since a polymer having a unit derived from an alkylene oxide is generally in a rubber state, it is produced by integrally extruding a conductive substrate and an unvulcanized rubber composition using an extruder equipped with a crosshead. It is preferable. A crosshead is an extrusion die that is used at the tip of a cylinder of an extruder, which is used to form a coating layer for electric wires and wires.

  Thereafter, after drying, curing, or crosslinking, the surface of the preliminary coating layer is polished to expose the conductive particles on the surface of the elastic layer. As a polishing method, a cylindrical polishing method or a tape polishing method can be used. Examples of the cylindrical polishing machine include a traverse type NC cylindrical polishing machine and a plunge cut type NC cylindrical polishing machine.

  As an example, preferred ranges for polishing conditions for the preliminary coating layer when using a plunge cut type cylindrical polishing machine are shown below.

  The rotational speed of the cylindrical grinding wheel is preferably 500 rpm or more and 4000 rpm or less. The penetration speed into the preliminary coating layer is preferably 5 mm / sec or more and 30 mm / sec or less. At this time, the speed may be decreased sequentially as it enters. A break-in process may be included at the end of the intrusion process. The spark-out process (polishing process at an intrusion rate of 0 mm / min) is preferably set to 10 seconds or less. When the member on which the preliminary coating layer is formed has a rotatable shape (for example, in the case of a roller shape), the number of rotations is preferably set to 50 rpm or more and 500 rpm or less.

  The conductive particles exposed at the interface may be single particles or aggregates, but the particle diameter of the conductive particles is preferably 1 μm or more and 200 μm or less in terms of volume average particle diameter. In particular, the thickness is more preferably 3 μm or more and 100 μm or less.

  As a means for controlling the particle size of the conductive particles within the above range, the particles may be controlled by pulverization or dispersion. However, since the particle size within the above range is a very narrow range, anyway, it is necessary to go through a step of dispersing in a polymer. As the dispersing means, since the polymer is generally in a rubber state, it is preferably dispersed using a rubber kneading apparatus. Examples of the kneading apparatus include a hermetic mixer and a two-roller.

  Particularly preferred as a means for controlling the dispersion to the polymer in the rubber state is a two-roll kneader, the gap between the two rolls is 2.0 mm or less, the kneading temperature is 30 ° C. or less, The particle size of the graphite particles and / or graphitized particles can be made close to the primary particle size.

(Surface layer)
The surface layer of the charging member contains a binder resin and resin particles dispersed in the binder resin. The surface layer of the charging member has conductivity.

(Binder resin)
Examples of the binder resin used for the surface layer of the charging member include known rubbers or resins. Examples of the rubber include natural rubber, a vulcanized product thereof, and synthetic rubber. Examples of the synthetic rubber include ethylene propylene rubber, styrene butadiene rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), acrylic rubber, and epichlorohydrin rubber. And fluororubber. Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, acrylic urethane resin, silicone resin, and butyral resin.

  These may be used alone or in combination of two or more. Moreover, the monomer which is the raw material of these binder resin is copolymerized, and it is good also as a copolymer. The surface layer of the charging member may be formed by adding a crosslinking agent to the prepolymerized binder resin material and curing or crosslinking.

(Resin particles)
Examples of the resin particles contained in the surface layer of the charging member include particles made of the following polymer compounds. Acrylic resin, styrene resin, polyamide resin, silicone resin, vinyl chloride resin, vinylidene chloride resin, acrylonitrile resin, fluororesin, phenol resin, polyester resin, melamine resin, urethane resin, olefin resin, epoxy resin, copolymer of these Modified products, resins such as derivatives, ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, chloroprene rubber (CR), Polyolefin thermoplastic elastomer, urethane thermoplastic elastomer, polystyrene thermoplastic elastomer, fluororubber thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, polyb Diene-based thermoplastic elastomers, ethylene vinyl acetate type thermoplastic elastomers, polyvinyl chloride thermoplastic elastomer, a thermoplastic elastomer such as chlorinated polyethylene based thermoplastic elastomer. Among these, from the viewpoint that it is easy to maintain a gap for generating an in-nip discharge with the electrophotographic photosensitive member when a convex portion is formed on the surface of the charging member (surface of the surface layer). It is preferable to use styrene resin or urethane resin.

  The resin particles may be used alone or in combination of two or more, and may be subjected to surface treatment, modification, introduction of functional groups or molecular chains, coating, and the like.

  The resin particles contained in the surface layer of the charging member are preferably multi-hollow particles and porous particles. This makes it easier to control the positional relationship between the exposed portions of the conductive particles in the elastic layer and the resin particles in the surface layer. The porous particles and multi-hollow particles of the present invention will be described below.

  The porous particles have a plurality of pores having a region containing air inside, the internal pores are not penetrating the resin particle surface, and the portions other than the pores are A particle having a large number of pores penetrating the resin particle surface. Examples of the material of the porous particles include acrylic resin, styrene resin, acrylonitrile resin, vinylidene chloride resin, and vinyl chloride resin. These resins can be used alone or in combination of two or more. The porous particles should be prepared by a known production method such as suspension polymerization method, interfacial polymerization method, interfacial precipitation method, in-liquid drying method, or a method of adding and precipitating a solute or solvent that lowers the solubility of the resin in the resin solution. Can do.

  The multi-hollow particles have a plurality of holes having a region containing air inside, and the inner holes are particles not penetrating the resin particle surface. Examples of the material of the multi-hollow particles include the same resins as the porous particles. These resins can be used alone or in combination of two or more. Multi-hollow particles can be produced by a known production method such as a suspension polymerization method, an interfacial polymerization method, an interfacial precipitation method, or a submerged drying method.

  The content of the resin particles in the surface layer of the charging member is preferably 2 parts by mass or more and 100 parts by mass or less, and more preferably 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin. The volume particle diameter of the resin particles is preferably 5 μm or more and 100 μm or less, and more preferably 15 μm or more and 60 μm or less. By setting it within these ranges, the degree of adhesion of the low molecular weight siloxane compound from the surface layer of the photoreceptor to the convex portion derived from the resin particles is increased, so that the effects of the present invention can be sufficiently obtained. .

  The volume average particle diameter of the resin particles is measured as follows (Measurement Method 1-5). The “three-dimensional particle shape” of the resin particles is calculated by the method described in the measurement method 1-2. For the obtained “stereoscopic particle shape” particles, the total volume including the region including air is calculated, and the diameter of a sphere having a volume equal to this volume is obtained. A total of 100 average particle diameters obtained are calculated and set as the volume average particle diameter of the particles.

  Further, the positional relationship between the resin particles in the surface layer and the graphite particles and graphitized particles on the surface of the elastic layer is confirmed by the following method (measurement method 1-6). The three-dimensional particle shape of the conductive particles (graphite particles and graphitized particles) exposed from the elastic layer is calculated by the method described in the above measurement method 1-2, and the three-dimensional shape of the resin particles calculated simultaneously is calculated. The correct particle shape is orthographically projected onto the surface of the elastic layer. This operation is performed at any 10 measured positions of the charging member to confirm the positional relationship.

(Conductive agent)
The surface layer of the charging member preferably contains a known conductive agent in order to develop conductivity. As the conductive agent, metal particles such as aluminum, palladium, iron, copper and silver, metal oxide particles such as titanium oxide, tin oxide and zinc oxide, and the surface of the metal particles or metal oxide particles are subjected to electrolytic treatment. And composite fine particles, carbon black, and carbon-based fine particles obtained by surface treatment by spray coating or mixing and shaking.

  Among these conductive agents, it is preferable to use particles containing carbon black from the viewpoint of conductivity control. Furthermore, it is more preferable to use silica particles coated with carbon black from the viewpoint of improving dispersibility.

  Examples of carbon black include black furnace black, thermal black, acetylene black, and ketjen black. Examples of the carbon-based fine particles include PAN (polyacrylonitrile) -based carbon particles and pitch-based carbon particles. Moreover, a electrically conductive agent can be used individually or in combination of 2 or more types.

  The particles containing carbon black preferably have an average particle size of 0.01 μm to 0.3 μm.

  The content of the conductive agent contained in the surface layer of the charging member is 2 parts by mass or more and 200 parts by mass or less, preferably 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin.

  The surface of the conductive agent may be treated. As the surface treatment agent, organosilicon compounds such as alkoxysilanes, fluoroalkylsilanes, and polysiloxanes, various silane, titanate, aluminate, and zirconate coupling agents, oligomers, or polymer compounds can be used. These may be used alone or in combination of two or more. Preferred are organosilicon compounds such as alkoxysilanes and polysiloxanes, silane-based, titanate-based, aluminate-based and zirconate-based coupling agents, and more preferable are organosilicon compounds.

  In the charging member, the ratio of the volume average particle diameter of the resin particles in the surface layer to the volume average particle diameter of the conductive particles in the elastic layer (resin particles / graphite particles or graphitized particles) is 0.08 or more and 35 or less. Preferably, it is 0.1 or more and 25 or less, and more preferably 0.4 or more and 12 or less. The ratio of the resin particle content in the surface layer to the conductive particle content in the elastic layer (resin particles / graphite particles or graphitized particles) is preferably 0.1 or more and 20 or less. 4 or more and 15 or less are more preferable, and 0.7 or more and 10 or less are particularly preferable.

(Other materials)
The surface layer of the charging member may contain insulating particles in addition to the conductive agent.
Examples of the insulating particles include zinc oxide, tin oxide, indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.), iron oxide, silica, alumina, magnesium oxide, zirconium oxide, strontium titanate, calcium titanate, Magnesium titanate, barium titanate, calcium zirconate, barium sulfate, molybdenum disulfide, calcium carbonate, magnesium carbonate, dolomite, talc, kaolin clay, mica, aluminum hydroxide, magnesium hydroxide, zeolite, wollastonite, diatomaceous earth, Examples thereof include particles of glass beads, bentonite, montmorillonite, hollow glass spheres, organometallic compounds, and organometallic salts. Further, iron oxides such as ferrite, magnetite, and hematite, and activated carbon can also be used.

The volume resistivity of the surface layer of the charging member is preferably 1 × 10 ² Ω · cm or more and 1 × 10 ¹⁶ Ω · cm or less in a temperature 23 ° C./humidity 50% RH environment.

  The surface layer of the charging member may further contain a release agent in order to improve the releasability. By including a release agent, it is possible to suppress the adhesion of dirt on the surface of the charging member and to improve the durability of the charging member. When the release agent is a liquid, it acts as a leveling agent when forming the conductive resin layer.

  The surface layer of the charging member may be subjected to a surface treatment. Examples of the surface treatment include a surface processing treatment using UV or electron beam and a surface modification treatment for adhering and / or impregnating a compound on the surface.

[Method for forming surface layer]
Examples of the method for forming the surface layer of the charging member include the following methods. First, an elastic layer having an exposed portion of the conductive particles on the surface is formed on the conductive substrate by the method described above. Next, the surface of the elastic layer is covered with a layer of a resin composition, followed by drying, curing, or crosslinking. Coating methods include electrostatic spray coating method, dipping coating method, roll coating method, method of bonding or coating a sheet-shaped or tube-shaped layer formed in a predetermined film thickness, and the outer peripheral portion of the elastic layer in the mold And a method in which the resin composition is disposed and cured. In order to control the positional relationship between the resin particles in the surface layer and the conductive particles exposed on the surface of the elastic layer, among these, the surface layer is formed by electrostatic spray coating, dipping coating, roll coating, etc. It is preferred to use the method.

  Moreover, when using these coating methods, the coating liquid (coating liquid for surface layers) of the resin composition which disperse | distributed the electrically conductive agent and the resin particle in binder resin is prepared. Furthermore, in order to make the control of the positional relationship easier, it is preferable to use a solvent having a high affinity for the polymer having units derived from alkylene oxide in the coating solution for the surface layer.

  Specific examples of the solvent include the following. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Alcohols such as methanol, ethanol and isopropanol; Amides such as N, N-dimethylformamide and N, N-dimethylacetamide; Sulfoxides such as dimethyl sulfoxide; Tetrahydrofuran , Ethers such as dioxane and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate.

  In addition, as a method of dispersing the binder resin and the conductive agent in the surface layer coating solution, solution dispersing means such as a ball mill, a sand mill, a paint shaker, a dyno mill, and a pearl mill can be used.

  The reason why it becomes easier to control the positional relationship between the resin particles and the conductive particles exposed on the surface of the elastic layer when the surface layer is formed by the above-described method.

  When a coating film of the surface layer coating solution is formed on the surface of the elastic layer where the conductive particles are exposed, first, a wet film containing a solvent (301 in FIG. 8) is formed on the surface of the elastic layer 2. . Since the solvent in the coating solution has a high affinity with the polymer having units derived from alkylene oxide, it is considered that the solvent penetrates into the elastic layer immediately after coating. On the other hand, since the conductive particles have low affinity with the solvent, the solvent does not penetrate. Due to the difference in solvent penetration at the surface of the elastic layer, the solvent penetrates into the elastic layer while forming a flow as indicated by a dotted line (302) in FIG. By such a flow of the solvent, the resin particles dispersed in the surface layer coating liquid are reliably arranged above the portions other than the graphite particles or graphitized particles exposed on the surface of the elastic layer. Is considered.

[Electrophotographic photoconductor]
The electrophotographic photosensitive member used in the process cartridge of the present invention has a siloxane compound in the surface layer.

  A siloxane compound refers to a silicone oil or a resin having a siloxane structure.

  An example of the layer structure of the electrophotographic photosensitive member is shown in FIGS. 7A and 7B, 201 is a support, 202 is an undercoat layer, 203 is a photosensitive layer, 204 is a charge generation layer, and 205 is a charge transport layer.

(Support)
As a support body, what has electroconductivity (conductive support body) is preferable. For example, metals or alloys, such as aluminum, stainless steel, copper, nickel, zinc, are mentioned. In the case of an aluminum or aluminum alloy support, an ED tube, an EI tube, or a support obtained by cutting, electrolytic composite polishing, wet or dry honing treatment of these can also be used. Moreover, what formed the thin film of electroconductive materials, such as aluminum, an aluminum alloy, or an indium oxide tin oxide alloy, on the metal support body and the resin support body is also mentioned.

  In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated in a resin, or a plastic having a conductive binder resin can also be used.

  The surface of the conductive support may be subjected to cutting treatment, roughening treatment, alumite treatment, etc. for the purpose of preventing interference fringes due to scattering of laser light or the like.

  In the electrophotographic photoreceptor, a conductive layer having conductive particles and a resin may be provided on the support. The conductive layer is a layer formed using a coating film of a conductive layer coating liquid in which conductive particles are dispersed in a binder resin.

  Examples of the conductive particles include carbon black, acetylene black, metal powders such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powders such as conductive tin oxide and ITO.

  Examples of the binder resin used for the conductive layer include polyester resin, polycarbonate resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. Examples of the solvent for the conductive layer coating solution include ether solvents, alcohol solvents, ketone solvents, and aromatic hydrocarbon solvents.

  An undercoat layer may be provided between the support or the conductive layer and the photosensitive layer. The undercoat layer can be formed by forming a coating film of an undercoat layer coating solution containing a binder resin on a support or a conductive layer, and drying or curing the coating film.

  Examples of the binder resin for the undercoat layer include polyacrylic acids, methyl cellulose, ethyl cellulose, polyamide resin, polyimide resin, polyamide imide resin, polyamic acid resin, melamine resin, epoxy resin, and polyurethane resin.

  The thickness of the undercoat layer is preferably 0.05 μm or more and 40 μm or less, and more preferably 0.1 μm or more and 30 μm or less. Examples of the solvent for the undercoat layer coating liquid include ether solvents, alcohol solvents, ketone solvents, and aromatic hydrocarbon solvents. Further, the undercoat layer may contain one or more metal oxide particles, semiconductive particles, electron transport materials, or electron accepting materials.

(Photosensitive layer)
A photosensitive layer (charge generation layer, charge transport layer) is formed on the support, the conductive layer, or the undercoat layer. More preferably, the photoconductive layer is preferably a laminated photosensitive layer composed of a charge generation layer and a charge transport layer formed on the charge generation layer.

  Examples of the charge generating material used in the electrophotographic photoreceptor include azo pigments, phthalocyanine pigments, indigo pigments, and perylene pigments. These charge generation materials may be used alone or in combination of two or more. Among these, oxytitanium phthalocyanine, hydroxygallium phthalocyanine, chlorogallium phthalocyanine and the like are particularly preferable because of high sensitivity.

  In the case of a laminated photosensitive layer, examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, butyral resin, polyvinyl acetal resin, acrylic resin, vinyl acetate resin, urea resin and the like. Among these, a butyral resin is particularly preferable. These resins can be used alone or in combination of two or more as a mixture or a copolymer.

  The charge generation layer can be formed by forming a coating film of a coating solution for a charge generation layer obtained by dispersing a charge generation material together with a binder resin and a solvent, and drying the coating film. The charge generation layer may be a vapor generation film of a charge generation material.

  The thickness of the charge generation layer is preferably from 0.01 μm to 5 μm, and more preferably from 0.1 μm to 2 μm. Examples of the solvent used in the charge generation layer coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary. Further, in order to prevent the flow of electric charges (carriers) in the charge generation layer, the charge generation layer may contain an electron transport material and an electron accepting material.

  In the case of a laminated photosensitive layer, a charge transport layer is provided on the charge generation layer. The charge transport layer is preferably a surface layer.

  Examples of the charge transport material contained in the charge transport layer include triarylamine compounds, hydrazone compounds, styryl compounds, and stilbene compounds. These charge transport materials may be used alone or in combination of two or more.

  Examples of the binder resin used for the charge transport layer include acrylic resin, styrene resin, polyester resin, polycarbonate resin, polyarylate resin, polysulfone resin, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. It is done. These can be used alone or in combination as a mixture or copolymer.

  The ratio of the charge transport material to the binder resin (charge transport material: binder resin) is preferably in the range of 2: 1 to 1: 2 (mass ratio).

  The surface layer (charge transport layer) of the electrophotographic photosensitive member has a siloxane compound. A siloxane compound refers to a resin having a siloxane structure at the terminal of a silicone oil or polymer, or at least a part of a repeating structure.

  Examples of the silicone oil include dimethyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, and modified silicone oil in which an organic group is introduced into a side chain or a terminal of a siloxane structure. Examples of the resin having a siloxane structure include an acrylic resin, a polycarbonate resin, and a polyester resin having a siloxane structure at the terminal of the polymer or at least a part of the repeating structure.

  The thickness of the charge transport layer is preferably 5 to 50 μm, more preferably 10 to 30 μm. The mass ratio of the charge transport material and the binder resin is 5: 1 to 1: 5, preferably 3: 1 to 1: 3.

  For the surface layer, hexanol, heptanol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, diethylene glycol ethyl methyl ether, ethylene carbonate, propylene carbonate, nitrobenzene, pyrrolidone, N -At least one compound (additive) selected from the group consisting of methylpyrrolidone, methyl benzoate, ethyl benzoate, benzyl acetate, ethyl 3-ethoxypropionate, acetophenone, methyl salicylate, dimethyl phthalate and sulfolane It is preferable to contain. When these compounds (additives) are contained, it is considered that these compounds (additives) are preferentially affected by discharge during discharge from the charging member, so that the low molecular weight of the siloxane compound is suppressed. .

  The content of the preferred compound (additive) is 0.1% by mass or more and 2.0% by mass or less with respect to the total mass of the surface layer.

  Since the above compound is a compound that is likely to volatilize in the step of heating and drying the coating film when forming the surface layer, the content of the above compound in the coating solution for the surface layer is the surface layer in consideration of the volatile matter. It is preferable that the content is larger than the content of the above-mentioned compound. Therefore, the content of the compound in the surface layer coating solution is preferably 1% by mass or more and 30% by mass or less with respect to the total mass of the surface layer coating solution.

  Content of the said compound in a surface layer can be calculated | required with the measuring method shown below (measuring method 2-1). It measured using HP7694 Headspace sampler (Agilent Technology Co., Ltd. product) and HP6890 series GS System (Agilent Technology Co., Ltd. product). The setting of the headspace sampler was set to 150 ° C. for Oven 150 ° C., 170 ° C. for Loop, and 190 ° C. for Transfer Line. The electrophotographic photosensitive member having a surface layer was cut into 5 mm × 40 mm pieces (sample pieces), put into vials, set in the headspace sampler, and the generated gas was measured by gas chromatography (HP6890 series GS System). The mass of the surface layer was determined from the difference between the mass of the sample piece with the surface layer taken out from the vial and the mass of the sample piece after peeling off the surface layer. The sample piece from which the surface layer was peeled was obtained by immersing the sample piece taken out from the vial bottle in methyl ethyl ketone for 5 minutes to peel off the surface layer and drying at 100 ° C. for 5 minutes. Also in this invention, content of the said compound in a surface layer was measured using the above-mentioned method.

  Various additives can be added to each layer of the electrophotographic photoreceptor. Examples of the additive include deterioration preventing agents such as antioxidants, ultraviolet absorbers, and light resistance stabilizers, and fine particles such as organic fine particles and inorganic fine particles. Examples of the deterioration inhibitor include hindered phenol antioxidants, hindered amine light resistance stabilizers, sulfur atom-containing antioxidants, and phosphorus atom-containing antioxidants. Examples of the organic fine particles include polymer resin particles such as fluorine atom-containing resin particles, polystyrene fine particles, and polyethylene resin particles. Examples of the inorganic fine particles include metal oxide fine particles such as silica and alumina.

[Electrophotographic equipment]
FIG. 4 shows a schematic configuration of an example of an electrophotographic apparatus having a charging member and an electrophotographic photosensitive member.

  The electrophotographic apparatus includes an electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, a latent image forming device that performs exposure, a developing device that develops a toner image, a transfer device that transfers to a transfer material, and an electrophotographic photosensitive member. A cleaning device for collecting the transfer toner, a fixing device for fixing the toner image, and the like are included.

  The electrophotographic photoreceptor 4 is a rotating drum type having a photosensitive layer on a support. The electrophotographic photosensitive member is rotationally driven at a predetermined peripheral speed (process speed) in the direction of the arrow.

  The charging device includes a contact-type charging roller 5 (charging member) that is placed in contact with the electrophotographic photosensitive member 4 by contacting with the electrophotographic photosensitive member 4 with a predetermined pressing force. The charging roller 5 is driven rotation that rotates in accordance with the rotation of the electrophotographic photosensitive member, and charges the electrophotographic photosensitive member to a predetermined potential by applying a predetermined DC voltage or direct / AC voltage from the charging power source 19. .

  As the latent image forming apparatus 11 that forms an electrostatic latent image on the electrophotographic photosensitive member 4, for example, an exposure apparatus such as a laser beam scanner is used. An electrostatic latent image is formed by performing exposure corresponding to image information on the uniformly charged electrophotographic photosensitive member.

  The developing device has a developing sleeve or a developing roller 6 disposed close to or in contact with the electrophotographic photosensitive member 4. The toner electrostatically processed to the same polarity as the charged polarity of the electrophotographic photosensitive member is reversely developed to develop the electrostatic latent image to form a toner image. The transfer device has a contact-type transfer roller 8. The toner image is transferred from the electrophotographic photosensitive member to a transfer material 7 such as plain paper. The transfer material is conveyed by a paper feeding system having a conveying member.

  The cleaning device has a blade-type cleaning member 10 and a collection container 14 and mechanically scrapes and collects transfer residual toner remaining on the electrophotographic photosensitive member after transfer. Here, it is possible to omit the cleaning device by adopting a development simultaneous cleaning system in which the transfer device collects the transfer residual toner. The fixing device 9 is constituted by a heated roll or the like, and fixes the transferred toner image on the transfer material 7 and discharges it outside the apparatus.

[Process cartridge]
An electrophotographic photosensitive member, a charging device (charging member), a developing device, a cleaning device, and the like may be integrated, and a process cartridge (FIG. 5) designed to be detachable from the main body of the electrophotographic device may be used.

  The electrophotographic apparatus is not particularly limited as long as it has the charging member and the electrophotographic photosensitive member. However, the electrophotographic apparatus may be configured to include the process cartridge, an exposure apparatus, and a developing apparatus.

  Hereinafter, the present invention will be described in more detail by way of specific examples. First, in advance of the measurement method of various parameters in the present invention, production examples A1 to 10 of graphite particles and graphitized particles, production examples B1 to 10 of resin particles, and silica particles (conductive agent) coated with carbon black. Production Examples C1 to 3, Production Examples of Titanium Oxide Particles (Conducting Agent) Production Example C5, Production Examples D1 to 26 of the charging roller, and Production Examples E1 to 33 of the electrophotographic photosensitive member will be described. In addition, “average particle diameter” for the following particles means “volume average particle diameter” unless otherwise specified. “Parts” in Examples and Comparative Examples means “parts by mass”.

  Measurement of the distance between the graphite (002) planes of the graphite particles and graphitized particles contained in the elastic layer (plane spacing of graphite (chemicalized) particles A1 to A10 described later) was measured by the measurement method 1-1 described above. The results are shown in Table 1.

The volume average particle diameter of the resin particles is measured by the method described in Measurement Method 1-5 above.
The ratio of major axis / minor axis of graphite particles and graphitized particles is measured by the method described in Measurement Method 1-4 above.
The volume average particle diameter of the graphite particles and graphitized particles is measured by the method described in Measurement Method 1-3 above.
The positional relationship between the resin particles in the surface layer and the graphite particles and graphitized particles on the surface of the elastic layer is measured by the method described in Measurement Method 1-6 above.
The content of the compound in the surface layer of the electrophotographic photosensitive member is measured by the method described in Measurement Method 2-1.

<1. Examples of production of graphite particles and graphitized particles>
[Production Example A1, production of graphite particles A1]
After pulverizing graphite particles having a scaly shape (produced by Ito Graphite Industries Co., Ltd .: CPN35 (trade name)) to have a volume average particle diameter of 2 μm, classification was performed to obtain graphite particles A1.

[Production Examples A2 and A3, Production of Graphite Particles A2 and A3]
Graphite particles A2 and A3 were obtained in the same manner as in Production Example A1, except that the particles were pulverized so as to have a volume average particle diameter of 3 μm or 6 μm and then classified.

[Production Examples A4 and A5, Production of Graphite Particles A4 and A5]
Graphite particles having a scaly shape (Ito Graphite Industry Co., Ltd .: Z-50 (trade name)) are pulverized to a volume average particle size of 40 μm or 70 μm, and then classified to obtain graphite particles A4 and A5. Obtained.

[Production Example A6, Production of Graphitized Particle A6]
Coal heavy oil was heat-treated, and the generated crude mesocarbon microbeads were centrifuged, washed with benzene, purified and dried. Subsequently, mechanical dispersion was performed with an atomizer mill to obtain mesocarbon microbeads. The mesocarbon microbeads were carbonized by raising the temperature to 1200 ° C. at a temperature raising rate of 600 ° C./h in a nitrogen atmosphere, followed by secondary dispersion in an atomizer mill. At that time, the volume average particle size was adjusted to about 3 μm. The obtained dispersion was heated to 3500 ° C. at a temperature rising rate of 1000 ° C./h under a nitrogen atmosphere, and heat-treated at 3500 ° C. for 15 minutes. Furthermore, classification treatment was performed to obtain graphitized particles A6.

[Production Examples A7 to A8, Production of Graphitized Particles A7 to A8]
In Production Example A6, the volume average particle size was adjusted to about 50 μm or 90 μm during secondary dispersion with an atomizer mill. The obtained dispersion was heated to 3000 ° C. at a heating rate of 1000 ° C./h under a nitrogen atmosphere, and heat-treated at 3000 ° C. for 15 minutes. Furthermore, classification treatment was performed to obtain graphitized particles A7 to A8, respectively.

[Production Example A9, Production of Graphitized Particles A9]
The coal tar was distilled to remove a light oil having a boiling point of 270 ° C. or less, and 85 parts of acetone was mixed with 100 parts of the tar part, followed by stirring at room temperature, and then the generated insoluble matter was removed by filtration. Acetone was separated by distillation of the filtrate to obtain purified tar. 10 parts of concentrated nitric acid was added to 100 parts of the purified tar obtained, subjected to polycondensation treatment at 350 ° C. for 1 hour in a vacuum distillation kettle, and further heated at 480 ° C. for 4 hours. This was taken out after cooling and mechanically pulverized, then heated to 1000 ° C. at a heating rate of 100 ° C./h in a nitrogen atmosphere, and subjected to heat treatment (primary heat treatment) at 1000 ° C. for 10 hours. During the pulverization, the average particle size was adjusted to about 3 μm. Subsequently, in a nitrogen atmosphere, the temperature was raised to 3000 ° C. at a rate of temperature increase of 100 ° C./h, and heat treatment (secondary heat treatment) was performed at 3000 ° C. for 1 hour. Furthermore, classification treatment was performed to obtain graphitized particles A9.

[Production Example A10, Production of Graphitized Particles A10]
After heat-stabilizing phenol resin particles with an average particle size of 2.3 μm in an oxidizing atmosphere at 300 ° C. for 1 hour, the temperature is increased to 2200 ° C. at a temperature increase rate of 1100 ° C./h, and heat treatment is performed at 2200 ° C. for 10 minutes Was given. Furthermore, classification treatment was performed to obtain graphitized particles A10.

[Evaluation of graphite particles and graphitized particles]
For each of the graphite particles and graphitized particles A1 to A10 obtained in each of the above production examples, the volume average particle diameter, the ratio of major axis / minor axis, and the interplanar spacing of the graphite (002) plane were measured. The results are shown in Table 1.

<2. Example of resin particle production>
[Production Example B1, Production of Resin Particle B1]
An aqueous medium was prepared by adding 8 parts of tricalcium phosphate to 400 parts of deionized water. Next, 20 parts of methyl methacrylate, 10 parts of 1,6-hexanediol methacrylate, 75 parts of n-hexane, and 0.3 part of benzoyl peroxide were mixed to prepare an oily mixture. The oily mixture was dispersed in an aqueous medium at a rotation speed of 10,000 rpm with a homomixer. Then, it charged into the polymerization reaction container substituted with nitrogen, and suspension polymerization was performed over 6 hours at 60 degreeC, stirring at 250 rpm, and the aqueous suspension containing a porous resin particle and n-hexane was obtained. To this aqueous suspension, 0.4 part of sodium dodecylbenzenesulfonate was added, and the concentration of sodium dodecylbenzenesulfonate was adjusted to 0.1% by mass with respect to water.

  The obtained aqueous suspension was distilled to remove n-hexane, and the remaining aqueous suspension was repeatedly filtered and washed with water, and then dried at 80 ° C. for 5 hours. Crushing and classification were performed with a sonic classifier to obtain resin particles B1 having a volume average particle size of 5.5 μm. When the cross section of the particle was observed by the method described above, the resin particle B1 was a porous particle having a large number of pores therein.

[Production Examples B2 and B3, Production of Resin Particles B2 and B3]
Resin particles B2 (volume average particle size 18.3 μm) and B3 (volume average particle size 30.5 μm) were obtained in the same manner as in Production Example B1, except that the rotation speed of the homomixer was changed to 5000 rpm and 3000 rpm, respectively. . All the resin particles were porous particles like the resin particles B1.

[Production Example B4, Production of Resin Particle B4]
An aqueous medium was prepared by adding 8 parts of polyvinyl alcohol (saponification degree: 85%) to 400 parts of deionized water. Next, 6.5 parts of methyl methacrylate, 6.5 parts of styrene, 9 parts of divinylbenzene, 85 parts of n-hexane, and 0.3 part of lauroyl peroxide were mixed to prepare an oily mixture. The oily mixture was dispersed in an aqueous medium at a rotation speed of 1800 rpm with a homomixer. Then, it charged into the polymerization reaction container substituted with nitrogen, and suspension polymerization was performed over 6 hours at 60 degreeC, stirring at 250 rpm, and the aqueous suspension containing a porous resin particle and n-hexane was obtained. Thereafter, resin particles B4 (volume average particle size 51 μm) were obtained in the same manner as in Production Example B1. This resin particle B4 was a porous particle similarly to the resin particle B1.

[Production Example B5, Production of Resin Particle B5]
Cross-linked polymethyl methacrylate resin particles (trade name: MBX-20, manufactured by Sekisui Plastics Co., Ltd.) were classified to obtain resin particles B5 having a volume average particle diameter of 18.2 μm. The resin particles of this production example did not have pores inside.
[Production Example B6, Production of Resin Particle B6]
Cross-linked polymethyl methacrylate resin particles (trade name: MBX-30, manufactured by Sekisui Plastics Kogyo Co., Ltd.) were classified to obtain resin particles B6 having a volume average particle size of 30.2 μm. The resin particles of this production example did not have pores inside.

[Production Example B7, Production of Resin Particle B7]
Cross-linked polystyrene resin particles (trade name: Chemisnow SGP, manufactured by Soken Kagaku Co., Ltd.) were classified to obtain resin particles B7 having a volume average particle size of 30.5 μm. The resin particles of this production example did not have pores inside.

[Production Example B8, Production of Resin Particle B8]
Crosslinked polyurethane resin particles (trade name: Dynamic Bead CM, manufactured by Dainichi Seika Kogyo Co., Ltd.) were classified to obtain resin particles B8 having a volume average particle size of 30.3 μm. The resin particles of this production example did not have pores inside.

[Production Example B9, Production of Resin Particle B9]
Silicone powder (trade name: KMP-602, manufactured by Shin-Etsu Silicone) was classified to obtain resin particles B9 having a volume average particle size of 30.2 μm. The resin particles of this production example did not have pores inside.

[Production Example B10, Production of Resin Particle B10]
Epoxy resin particles (trade name: Trepearl, manufactured by Toray Industries, Inc.) were classified to obtain resin particles B9 having a volume average particle size of 30.2 μm. The resin particles of this production example did not have pores inside.

[Characteristic evaluation of resin particles]
The volume average particle size of each of the resin particles B1 to B10 obtained in each of the above production examples and the resin particles used in the below-described charging roller production examples was measured. The results are shown in Table 1. Table 1 also shows the particle shape. The “solid” in the shapes of the resin particles B5 to B10 in Table 1 means that there are no pores inside the resin particles.

<3. Production Example of Conductive Agent>
[Production Example C1, production of silica C1 coated with carbon black]
To 7.0 kg of silica particles (average particle size 15 nm, volume resistivity 1.8 × 10 ¹² Ω · cm), 140 g of methyl hydrogen polysiloxane was added while operating the edge runner, and 588 N / cm (60 kg / cm The mixture was stirred for 30 minutes under a linear load. The stirring speed at this time was 22 rpm. Among them, 7.0 kg of carbon black “# 52” (trade name, manufactured by Mitsubishi Chemical Corporation) was added over 10 minutes while operating the edge runner, and further, 588 N / cm (60 kg / cm). Mixing and stirring were performed for 60 minutes under a linear load. Thus, after carbon black was made to adhere to the surface of the silica particle coat | covered with methyl hydrogen polysiloxane, it dried for 60 minutes at 80 degreeC using the dryer, and the silica particle C1 coat | covered with carbon black Was made. The stirring speed at this time was 22 rpm. The silica particles coated with the obtained carbon black had an average particle diameter of 15 nm and a volume resistivity of 1.1 × 10 ² Ω · cm.

[Production Examples C2 to C3, Production of Silica Particles C2 to C3 Coated with Carbon Black]
Silica particles C2 (average particle size 0.12 μm) coated with carbon black in the same manner as in Production Example C1, except that the average particle size of the silica particles was 0.1 μm, 0.4 μm, and 0.5 μm, respectively. C3 (average particle size 0.42 μm) was prepared.

[Production Example C5, preparation of surface-treated titanium oxide particles]
1000 g of acicular rutile type titanium oxide particles (average particle size 15 nm, length: width = 3: 1, volume resistivity 2.3 × 10 ¹⁰ Ω · cm), 110 g of isobutyltrimethoxysilane as a surface treatment agent, and toluene as a solvent A slurry was prepared by blending 3000 g. After mixing this slurry with a stirrer for 30 minutes, it is supplied to viscomill in which 80% of the effective internal volume is filled with glass beads having an average particle diameter of 0.8 mm, and wet crushing is performed at a temperature of 35 ± 5 ° C. It was. Toluene was removed from the slurry obtained by wet pulverization by vacuum distillation (bath temperature: 110 ° C., product temperature: 30-60 ° C., degree of vacuum: about 100 Torr) using a kneader, and the surface was kept at 120 ° C. for 2 hours. The treating agent was baked. The baked particles were cooled to room temperature and then pulverized using a pin mill to produce surface-treated titanium oxide particles. The obtained surface-treated titanium oxide particles had an average particle size of 15 nm and a volume resistivity of 5.2 × 10 ¹⁵ Ω · cm.

<Production of charging roller>
[Production Example D1, Production of Charging Roller D1]
(Conductive substrate)
A stainless steel substrate having a diameter of 6 mm and a length of 244 mm was coated with a thermosetting adhesive containing 10% by mass of carbon black and dried, and used as a conductive substrate.

(Preparation of conductive rubber composition)
Epichlorohydrin rubber (EO-EP-AGC ternary copolymer, EO / EP / AGE = 73 mol% / 23 mol% / 4 mol%) 100 parts as a polymer having an alkylene oxide-derived unit, calcium carbonate (trade name: Silver W 80 parts of Shiraishi Kogyo Co., Ltd., 8 parts of adipic acid ester (trade name: Polysizer W305ELS, manufactured by DIC Corporation), zinc stearate (trade name: SZ-2000, manufactured by Sakai Chemical Industry Co., Ltd.) 1 Part, 2-mercaptobenzimidazole (MB) (anti-aging agent) 0.5 part, zinc oxide (trade name: Zinc Hua 2 types, manufactured by Sakai Chemical Industry Co., Ltd.), quaternary ammonium salt “Adeka Sizer LV70 "(Trade name, manufactured by ADEKA Corporation) 2 parts, carbon black" Thermax Flow Foam N990 "(trade name, Canada Canc rb Co., average particle size: 270 nm) 5 parts, and the graphite particles A1 20 parts were mixed, and kneaded for 10 minutes in a closed-type mixer was adjusted to 50 ° C., to prepare a raw material compound.

  To this, 0.8 part of sulfur as a vulcanizing agent, 1 part of dibenzothiazyl sulfide (DM) and 0.5 part of tetramethylthiuram monosulfide (TS) were added as a vulcanization accelerator. Subsequently, it knead | mixed for 10 minutes with the double roll machine cooled at 20 degreeC, and produced the conductive rubber composition. At that time, the gap between the two rolls was adjusted to 1.5 mm.

  EO: ethylene oxide, EP: epichlorohydrin, AGE: allyl glycidyl ether.

[Production of elastic roller (elastic layer)]
Using an extrusion molding apparatus equipped with a cross head, the outer peripheral portion of the conductive base was covered with the conductive rubber composition in the form of a coaxial cylinder with the conductive base as the central axis to obtain a rubber roller. The thickness of the coated rubber composition was adjusted to 1.75 mm.

  The roller was heated in a hot air oven at 160 ° C. for 1 hour, and then the end of the elastic layer was removed to make the length 226 mm. Further, the roller was subjected to secondary heating at 160 ° C. for 1 hour to obtain a layer thickness of 1. A roller having a 75 mm pre-coating layer was prepared.

  The outer peripheral surface of the obtained roller was polished using a plunge cut type cylindrical polishing machine. A vitrified wheel was used as the polishing wheel, the abrasive grains were green silicon carbide (GC), and the particle size was 100 mesh. The rotational speed of the roller was 350 rpm, and the rotational speed of the grinding wheel was 2050 rpm. The rotation direction of the roller and the rotation direction of the grinding wheel were the same direction (driven direction). The cutting speed is changed stepwise from 10 mm / min to 0.1 mm / min from when the grinding wheel contacts the unpolished roller until it is polished to Φ9 mm, and the spark-out time (time at 0 mm cutting) is 5 seconds. An elastic roller was prepared by setting. The thickness of the elastic layer was adjusted to 1.5 mm. The crown amount of this roller (the difference in the outer diameter at a position 90 mm away from the central portion and the central portion) was set to 100 μm. When the surface of this elastic roller was cut out and observed with an electron microscope, the exposed portion of the graphite particles A1 could be observed.

(Preparation of coating solution for surface layer)
Methyl isobutyl ketone was added to a caprolactone-modified acrylic polyol solution “Placcel DC2016” (trade name, manufactured by Daicel Corporation) to adjust the solid content to 12% by mass. 834 parts of this solution (100 parts of acrylic polyol solid content), 60 parts of silica particles coated with carbon black (produced in Production Example C1), 50 parts of surface-treated titanium oxide particles (produced in Production Example C5), modified dimethyl silicon 0.08 part of oil “SH28PA” (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.) and 80.14 part of blocked isocyanate mixture (* 2) were mixed to prepare a mixed solution. At this time, the blocked isocyanate mixture was such that the amount of isocyanate was “NCO / OH = 1.0”.
(* 2) 7: 3 mixture of each butanone oxime block of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).

  Next, 188.5 g of the above mixed solution was put in a glass bottle having an internal volume of 450 mL together with 200 g of glass beads having an average particle diameter of 0.8 mm as a medium, and dispersed for 20 hours using a paint shaker disperser. After dispersion, 7.2 g of resin particle B3 was added. This is equivalent to 40 parts of resin particles B3 with respect to 100 parts of acrylic polyol solid content. Thereafter, dispersion was performed for 5 minutes, and the glass beads were removed to prepare a surface layer coating solution.

(Formation of surface layer)
The elastic roller was immersed in the surface layer coating solution with the longitudinal direction thereof set to the vertical direction, and was coated by a dipping method. The dipping time was 9 seconds, the pulling speed was an initial speed of 20 mm / s, and the final speed was 2 mm / s. During that time, the speed was changed linearly with respect to time. The obtained coating film was air-dried at 23 ° C. for 30 minutes, and then dried with a hot air circulating dryer at a temperature of 80 ° C. for 1 hour and further at a temperature of 160 ° C. for 1 hour to cure the coating film. A charging roller 1 (charging member) having a surface layer formed on the surface was obtained.

  The film thickness of the surface layer of the charging roller 1 was 5.2 μm. In addition, the film thickness of the surface layer was measured at a location where no resin particles exist.

(Measurement of spacing between graphite (002) planes)
By the method described above, the interplanar spacing of the graphite (002) plane of the graphite particles contained in the elastic layer was measured. The results are shown in Table 3.

(Measurement of various characteristic values of particles contained in each layer)
By the method described above, the volume average particle diameter of the graphite particles, the ratio of the major axis / minor axis of the graphite particles, the volume average particle diameter of the resin particles, and the shape of the resin particles were measured. The results are shown in Tables 2 and 3. Further, the volume average particle size ratio (resin particles / graphite particles) was calculated from the measurement results. Table 3 shows the measurement results.

(Positional relationship between resin particle B1 and graphite particle A1 on the surface of the elastic layer)
The positional relationship was confirmed by orthographic projection of the three-dimensional particle shape of the resin particle B3 onto the surface of the elastic layer by the method described above. In the charging roller D1, a portion other than the projected portion of the resin particle B1 in the surface layer overlapped with the exposed portion of the graphite particle A1. The results are shown in Table 3.

[Production Examples D2 to D25, Production of Charging Rollers D2 to D25]
The type and part of graphite particles or graphitized particles that are conductive particles at the time of preparation of the conductive rubber composition, and the type and part of resin particles at the time of preparation of the coating solution for the surface layer and carbon black Charging rollers 2 to 25 were obtained in the same manner as in Production Example D1, except that the types and mass parts of the silica particles (CB-coated silica particles) were changed as shown in Table 2.

  In Table 2, “CB-coated silica particles” means silica particles coated with carbon black.

[Production Example D26, Charging Roller D26]
A charging roller D26 was obtained in the same manner as in Production Example D1, except that the production of the conductive rubber composition in Production Example D1 was changed as follows.

  Butadiene rubber (BR) "JSR BR01" (trade name, manufactured by JSR Corporation) 100 parts, carbon black (trade name: Seast S, manufactured by Tokai Carbon Co., Ltd.) 40 parts, zinc stearate (trade name: SZ- 2000, Sakai Chemical Industry Co., Ltd.) 1 part, Zinc Oxide (trade name: Zinc Hana 2 types, Sakai Chemical Industry Co., Ltd.) 5 parts, Calcium Carbonate (trade name: Silver W, Shiraishi Kogyo Co., Ltd.) ) 20 parts and 50 parts of graphitized particles A11 were mixed and kneaded for 15 minutes in a closed mixer adjusted to 50 ° C.

  To this, 1.2 parts of sulfur as a vulcanizing agent and 4.5 parts of tetrabenzylthiuram disulfide (TBzTD) (trade name: Parkasit TBzTD, manufactured by Flexis) as a vulcanization accelerator were added and cooled to a temperature of 25 ° C. The conductive rubber composition was produced by kneading for 10 minutes with a two-roll mill. At this time, the gap between the two rolls was adjusted to 2.0 mm.

  In addition, Production Examples 24-26 are comparative production examples.

  In Table 3, “positional relationship” indicates the positional relationship between the exposed portions of the conductive particles in the elastic layer and the resin particles in the surface layer. “◯” indicates that when the resin particles in the surface layer are orthographically projected onto the surface of the elastic layer of the charging member, the portion other than the projected portion of the resin particles on the surface of the elastic layer of the charging member is exposed to the conductive particles. Indicates that it overlaps the part. “X” indicates that the portion other than the projected portion of the resin particles in the surface layer did not overlap with the exposed portion of the graphitized particles. In Production Examples D22 and D23, the columns of “average particle diameter of CB-coated silica particles” mean the average particle diameter of carbon black (Production Example D22) and the average particle diameter of tin oxide particles (Production Example D23), respectively. .

[Production Example E1, Production of Electrophotographic Photoreceptor E1]
An aluminum cylinder having a diameter of 24 mm and a length of 251.5 mm was used as a support.

As metal oxide particles, 120 parts of titanium oxide (TiO ₂ ) particles coated with tin oxide (SnO ₂ ) doped with phosphorus (P), phenol resin (monomer / oligomer of phenol resin) (trade name: ply Offen J-325, manufactured by Dainippon Ink & Chemicals, Inc., resin solid content: 60%) and 168 parts of 1-methoxy-2-propanol were used with 420 parts of glass beads having a diameter of 0.8 mm. It put into the sand mill, the dispersion process was performed on the conditions of rotation speed: 1500rpm, and dispersion processing time: 4 hours, and the dispersion liquid was obtained. The glass beads were removed from the dispersion with a mesh. To the dispersion liquid after removing the glass beads, 13.8 parts of silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials, average particle size: 2 μm), silicone oil (trade name: SH28PA, Toray Industries, Inc.) A conductive layer coating solution was prepared by adding 0.014 part (made by Dow Corning Co., Ltd.), 6 parts of methanol, and 6 parts of 1-methoxy-2-propanol and stirring.

  The conductive layer coating solution was dip-coated on a support, and the obtained coating film was cured (heat cured) at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.

  Next, an undercoat layer coating solution was prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol. This undercoat layer coating solution was dip-coated on the conductive layer, and the resulting coating film was dried at 80 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.8 μm.

  Next, 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 with Bragg angles 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction as charge generation materials. 10 parts of a crystalline hydroxygallium phthalocyanine crystal (charge generation material) having a strong peak at 0 ° was used. This was added to a solution obtained by dissolving 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 250 parts of cyclohexanone. This was dispersed in a sand mill apparatus using glass beads having a diameter of 1 mm in an atmosphere of 23 ± 3 ° C. for 1 hour, and 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution.

  This charge generation layer coating solution was dip-coated on the undercoat layer, and the resulting coating film was dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

(Preparation of surface layer)
Next, 6.0 parts of an amine compound (charge transport material) represented by the following formula (CTM-1), 2.0 parts of an amine compound (charge transport material) represented by the following formula (CTM-2), bisphenol Z type 10 parts of polycarbonate resin (trade name: Z400, manufactured by Mitsubishi Engineering Plastics), having a repeating structural unit represented by the following formula (B-1) and a repeating structural unit represented by the following formula (B-2) 0.18 parts of a siloxane-modified polycarbonate resin G having a terminal structure represented by the following formula (B-3) ((B-1) :( B-2) = 95: 5 (molar ratio)), o-xylene 24 parts, 40 parts of dimethoxymethane and 16 parts of methyl benzoate were mixed and dissolved to prepare a coating solution for charge transport layer. This charge transport layer coating solution was dip-coated on the charge generation layer, and the resulting coating film was dried at 125 ° C. for 30 minutes to form a charge transport layer having a thickness of 20 μm.

  It was confirmed by the above gas chromatography measurement that the formed charge transport layer (surface layer) contained 1.5% by mass of methyl benzoate.

[Production Examples E2 to E22, Production of Electrophotographic Photoconductors E2 to E22]
Electrophotographic photoreceptors E2 to E24 were prepared in the same manner as in Production Example E1, except that methyl benzoate in Production Example E1 was changed to the compounds shown in Table 4, respectively.

[Production Example E23, Production of Electrophotographic Photoreceptor E23]
An electrophotographic photoreceptor E23 was produced in the same manner as in Production Example E1, except that the amount of methyl benzoate added in Production Example E1 was changed to 3 parts.

[Production Example E24, Production of Electrophotographic Photoconductor E24]
An electrophotographic photoreceptor E24 was produced in the same manner as in Production Example E1, except that the drying temperature of Production Example E1 was changed to 120 ° C.

[Production Examples E25, E27, E29, E31, E33, Production of Electrophotographic Photoconductors E25, E27, E29, E31, E33]
The kind and addition amount of the siloxane compound of Production Example E1 were changed as shown in Table 4, respectively, except that methyl benzoate was not used, and 40 parts of o-xylene and 40 parts of dimethoxymethane were used. Thus, electrophotographic photoreceptors E25, E27, E29, E31, E33 were produced.

[Production Examples E26, E28, E30, E32, Production of Electrophotographic Photoconductors E26, E28, E30, E32]
Electrophotographic photoreceptors E26, E28, E30, and E32 were produced in the same manner as in Production Example E1, except that the type and addition amount of the siloxane compound of Production Example E1 were changed as shown in Table 4.

[Measurement of content of specific compound in surface layer of electrophotographic photoreceptor]
The content of the specific compound in the electrophotographic photoreceptors E1 to E32 was measured by the method described in the measurement method 2-1. The results are shown in Table 4.

[Example 1]
A monochrome laser printer (“LBP6300” (trade name)) manufactured by Canon Inc., which is an electrophotographic apparatus having the configuration shown in FIG. 4, was used, and the process speed was modified to 230 mm / s. Further, a voltage was applied to the charging member from the outside. The applied voltage was an AC voltage with a peak peak voltage (Vpp) of 2000 V, a frequency (f) of 1350 Hz, and a DC voltage (Vdc) of −400 V. The image resolution was output at 600 dpi. The process cartridge for the printer was used as the process cartridge.

  The attached charging roller and the electrophotographic photosensitive member were removed from the process cartridge, and the charging roller D1 and the electrophotographic photosensitive member E1 were set instead. Further, as shown in FIG. 6, the charging roller was brought into contact with the electrophotographic photosensitive member by a pressing force of a spring of 4.9 N at one end and a total of 9.8 N at both ends.

  The charging roller D1 and the electrophotographic photosensitive member E1 are set in the process cartridge. The process cartridge is temperature 15 ° C./humidity 10% RH environment (environment 1), temperature 23 ° C./humidity 50% RH environment (environment 2), and After acclimatization to a temperature 32.5 ° C./humidity 80% RH environment (environment 3) for 24 hours, image formation was performed in each environment.

For image formation, 10,000 horizontal line images having a width of 2 dots and an interval of 186 dots in the direction perpendicular to the rotation direction of the electrophotographic photosensitive member were output. The output of 10,000 sheets was image-formed under the condition that the rotation of the printer was stopped for 3 seconds every two sheets. Here, after outputting 2,500 images of the horizontal line image, after outputting 5,000 images, after outputting 7,500 images, after outputting 10,000 images, one halftone image was output. A halftone image is an image in which a horizontal line having a width of 1 dot and an interval of 3 dots is drawn in a direction perpendicular to the rotation direction of the electrophotographic photosensitive member. The four halftone images thus obtained (hereinafter referred to as “halftone images No. 1 to 4”) were visually observed, and image evaluations such as white stripes and white bands were determined based on the following criteria. In the present invention, ranks 1 and 2 are levels at which the effects of the present invention are obtained, and rank 1 is determined to be an excellent level among them. On the other hand, ranks 3 and 4 were judged as levels at which the effects of the present invention were not obtained. Table 7 shows the evaluation results.
Rank 1: Image defect is not recognized.
Rank 2: Only slight white streaks are recognized.
Rank 3: Some white belts can be confirmed by the pitch of the charging roller, but the deterioration of image quality is not noticeable.
Rank 4: The image defect due to the white belt of the pitch of the charging roller is conspicuous, and the image quality is deteriorated.

[Examples 2-125 and Comparative Examples 1-6]
The charging roller and the electrophotographic photosensitive member of Example 1 were evaluated in the same manner as in Example 1 with the combinations shown in Tables 5 and 6. The evaluation results are shown in Tables 7-9.

  By comparing the example with the comparative examples 3 and 6, the example can reduce the occurrence of image defects of white stripes and white bands in the environments 1 to 3. This is because when the polymer having an alkylene oxide-derived unit is used for the elastic layer of the charging member, the resin particles in the surface layer of the charging member are orthographically projected on the surface of the elastic layer of the charging member. This is considered to be because the portion other than the projected portion of the resin particle on the surface of the elastic layer is in a positional relationship that the exposed portion of the conductive particle overlaps. On the other hand, in Comparative Examples 3 and 6, since butadiene rubber is used, it is considered that the conductive particles and the resin particles did not have the above positional relationship.

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 Elastic layer 3 Surface layer 4 Electrophotographic photoreceptor 5 Charging member (charging roller)
6 Developing Roller 7 Transfer Material 8 Transfer Roller 9 Fixing Device 10 Cleaning Member 11 Latent Image Forming Device 14 Collection Container 19 Charging Power Source 101a, 101b, 101c Graphite Particles or Graphitized Particles 102 Resin Particles 103 Exposure of Graphite Particles or Graphitized Particles Part 105 Exposed part of conductive particle 106 Part other than projection part of resin particle 107 Projection view 108 Surface of elastic layer 201 Support 202 Subbing layer 203 Photosensitive layer 204 Charge generation layer 205 Charge transport layer

Claims (12)

In the process cartridge that integrally supports the electrophotographic photosensitive member and the charging member and is detachable from the main body of the electrophotographic apparatus,
The surface layer of the electrophotographic photoreceptor contains a siloxane compound,
The charging member has a conductive substrate, an elastic layer formed on the conductive substrate, and a surface layer formed on the elastic layer;
The elastic layer of the charging member contains a polymer having a unit derived from an alkylene oxide, and at least one conductive particle selected from the group consisting of graphite particles and graphitized particles,
The surface of the elastic layer of the charging member has an exposed portion where the conductive particles are exposed from the elastic layer;
The surface of the elastic layer of the charging member including the exposed portion of the conductive particles is covered with the surface layer of the charging member;
The surface layer of the charging member contains a binder resin and resin particles dispersed in the binder resin;
The surface of the surface layer of the charging member has a plurality of convex portions derived from the resin particles,
When the resin particles in the surface layer of the charging member are orthographically projected onto the surface of the elastic layer of the charging member, a portion other than the projected portion of the resin particles on the surface of the elastic layer of the charging member is A process cartridge, wherein the process cartridge overlaps the exposed portion of the conductive particles.   The process cartridge according to claim 1, wherein an average particle diameter of the conductive particles is 1 μm or more and 100 μm or less.   3. The process cartridge according to claim 1, wherein the conductive particles have a scaly shape, and a spacing between graphite (002) surfaces of the conductive particles is 0.3354 or more and 0.3365 or less.   The process cartridge according to claim 1, wherein the resin particles are particles of acrylic resin, styrene resin, or urethane resin.   The surface layer of the electrophotographic photoreceptor is hexanol, heptanol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, diethylene glycol ethyl methyl ether, ethylene carbonate, propylene carbonate At least one compound selected from the group consisting of nitrobenzene, pyrrolidone, N-methylpyrrolidone, methyl benzoate, ethyl benzoate, benzyl acetate, ethyl 3-ethoxypropionate, acetophenone, methyl salicylate, dimethyl phthalate and sulfolane The process cartridge according to any one of claims 1 to 4, further comprising:   The content of the compound in the surface layer of the electrophotographic photoreceptor is 0.1% by mass or more and 2.0% by mass or less based on the total mass of the surface layer of the electrophotographic photoreceptor. The described process cartridge. In an electrophotographic apparatus having an electrophotographic photosensitive member and a charging member,
The surface layer of the electrophotographic photoreceptor contains a siloxane compound,
The charging member has a conductive substrate, an elastic layer formed on the conductive substrate, and a surface layer formed on the elastic layer;
The elastic layer of the charging member contains a polymer having a unit derived from an alkylene oxide, and at least one conductive particle selected from the group consisting of graphite particles and graphitized particles,
The surface of the elastic layer of the charging member has an exposed portion where the conductive particles are exposed from the elastic layer;
The surface of the elastic layer of the charging member including the exposed portion of the conductive particles is covered with the surface layer of the charging member;
The surface layer of the charging member contains a binder resin and resin particles dispersed in the binder resin;
The surface of the surface layer of the charging member has a plurality of convex portions derived from the resin particles,
When the resin particles in the surface layer of the charging member are orthographically projected onto the surface of the elastic layer of the charging member, a portion other than the projected portion of the resin particles on the surface of the elastic layer of the charging member is An electrophotographic apparatus, wherein the electrophotographic apparatus overlaps the exposed portion of the conductive particles.   The electrophotographic apparatus according to claim 7, wherein an average particle diameter of the conductive particles is 1 μm or more and 100 μm or less.   9. The electrophotographic apparatus according to claim 7, wherein the conductive particles have a scaly shape, and an interval between graphite (002) surfaces of the conductive particles is 0.3354 or more and 0.3365 or less. .   The electrophotographic apparatus according to claim 7, wherein the resin particles are acrylic resin, styrene resin, or urethane resin particles.   The surface layer of the electrophotographic photoreceptor is hexanol, heptanol, cyclohexanol, benzyl alcohol, ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, diethylene glycol ethyl methyl ether, ethylene carbonate, propylene carbonate At least one compound selected from the group consisting of nitrobenzene, pyrrolidone, N-methylpyrrolidone, methyl benzoate, ethyl benzoate, benzyl acetate, ethyl 3-ethoxypropionate, acetophenone, methyl salicylate, dimethyl phthalate and sulfolane The electrophotographic apparatus according to any one of claims 7 to 10, further comprising: The content of the compound in the surface layer of the electrophotographic photoreceptor is 0.1% by mass or more and 2.0% by mass or less based on the total mass of the surface layer of the electrophotographic photoreceptor. The electrophotographic apparatus according to the description.

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