JP4217578B2 - Charging member, process cartridge and electrophotographic apparatus using the same - Google Patents

Description

  The present invention relates to a charging member having one or more coating layers on a conductive support, a process cartridge and an electrophotographic apparatus using the charging member.

In recent years, with the spread of computers and peripheral devices, the use of electrophotographic apparatuses as their output devices has been spread all over the world, and the environments in which they are used are also extremely diverse. Therefore, electrophotographic apparatuses and process cartridges used therefor are required to exhibit equally excellent performance even in various environments where they are used. As one means for improving the environmental characteristics of the electrophotographic apparatus and the process cartridge, it is effective to improve the environmental dependency of the charging member. For example, in the coating layer on the support, the degree of hydrophobicity is 20% or more, the average primary particle size is 0.5 μm or less, with respect to fluctuations in the resistance value of the charging roller that may occur in a high temperature and high humidity environment It is disclosed that a charging roller containing conductive fine particles having a specific surface area of 20 m ² / g or more and surface-treated with a coupling agent or oil is effective (see Patent Document 1). Further, as a charging roller having a small resistance change in a low-humidity environment, a charging roller having a coating layer containing a surface-treated conductive agent and having a friction coefficient of 1.0 or less on the periphery of the support is disclosed. (See Patent Document 2).

However, according to the study by the present inventors, a process cartridge left in an environment of high temperature and high humidity (for example, 40 ° C., 95% RH) sealed in a package is mounted on the electrophotographic apparatus main body to form an image. As a result, it was found that the resistance value on the surface of the charging member was partially reduced, thereby causing image unevenness in the electrophotographic image. This phenomenon is particularly remarkable in an electrophotographic apparatus that employs a system in which charging is performed by applying only a DC voltage to the charging member.
JP 2003-107825 A JP 2001-166563 A

The present invention has been made in view of such circumstances,
An object of the present invention is to provide a charging member whose charging characteristics hardly change even in various environments, particularly in a high temperature and high humidity environment. In particular, another object of the present invention is to provide an electrophotographic apparatus and a process cartridge that can provide a high-quality image more stably.

According to one aspect of the present invention, there is provided a charging member having a conductive support and a coating layer covering the periphery of the conductive support, the outermost surface of the charging member being Provided is a charging member, wherein the conductive surface layer constituting the material includes at least one selected from the following (i) and (ii):
(I) conductive fine particles and a compound represented by the following formula (1);
(Ii) Conductive fine particles whose surface is treated with a compound represented by the following formula (1) and insulating fine particles whose surface is treated with a compound represented by the following formula (1):
R _a -Si-X _4-a (1)
(In the formula (1), a is an integer of 1 to 3, R is an alkyl group having a branched chain, and X is a hydrolyzable group).

According to another aspect of the present invention, an electrophotographic photosensitive member that is a member to be charged;
There is provided a process cartridge characterized by integrally supporting the charging means having the charging member for charging the electrophotographic photosensitive member and being detachable from the main body of the electrophotographic apparatus.

  According to still another aspect of the present invention, an electrophotographic photosensitive member as a member to be charged, a charging unit having the charging member for charging the electrophotographic photosensitive member, an exposure unit, and a developing unit, An electrophotographic apparatus comprising: a transfer means;

  According to the present invention, even when the process cartridge is hermetically sealed and stored at high temperature and high humidity and then mounted on the main body of the electrophotographic apparatus to form an electrophotographic image, image unevenness derived from the charging member is extremely effectively suppressed. , Has the effect of. Alternatively, it can be said that the influence of the history of the environment through which the charging member has on the image quality can be suppressed very slightly.

  In addition, even in an electrophotographic apparatus in which only a DC voltage is applied to the charging member, which is likely to cause image unevenness derived from the charging member, the charging member-derived image can be obtained by employing the charging member according to the present invention. The occurrence of unevenness is extremely effectively suppressed.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, an aspect of the charging member according to the present invention includes a conductive support 2a, an elastic layer 2b as a covering layer covering the periphery of the conductive substrate, and a surface layer 2d. is doing. And the surface layer 2d constituting the outermost surface of the charging member includes at least one selected from the following (i) and (ii).
(I) conductive fine particles and a compound represented by the following formula (1);
(Ii) Conductive fine particles whose surface is treated with a compound represented by the following formula (1) and insulating fine particles whose surface is treated with a compound represented by the following formula (1):
R _a -Si-X _4-a (1)
(In the formula (1), a is an integer of 1 to 3, R is an alkyl group having a branched chain, and X is a hydrolyzable group).

a: Surface layer a-1: Compound represented by the above formula (1);
The compound represented by the above formula (1) is contained in the surface layer, or the surface treatment is performed with the conductive fine particles surface-treated with the compound represented by the above formula (1) and the compound represented by the above formula (1). It is not clear why the change in the surface resistance of the charging member due to the environment can be further suppressed by including the insulating fine particles in the surface layer. However, the partial decrease in surface resistance after being left in a high-temperature and high-humidity environment is suppressed because indirect or direct conduction between conductive fine particles in the surface layer is a bulky branched alkyl group. It is presumed that it is extremely effectively suppressed by the presence of.

  In the compound of the above formula (1), R is preferably a branched alkyl group having 4 or more and 10 or less carbon atoms, and even if it is the longest carbon chain in R, it is 5 or less carbon atoms. Is preferred. By making R such a structure, even when stored under high temperature and high humidity, the occurrence of uneven resistance can be more effectively suppressed, and as a result, an electrophotographic image in which unevenness is extremely effectively suppressed can be obtained. Can do. When a is 2 or 3, the alkyl groups may be the same or different from each other.

  Table 1 below shows specific examples of R.

In the above formula (1), X represents a hydrolyzable group. Here, in the structure of (i) in which the compound of the formula (1) is contained in the surface layer, X is an alkoxy group having 1 to 3 carbon atoms (methoxy group, ethoxy group, propoxy group). It is preferable. In the structure of (ii), the surface layer contains conductive fine particles surface-treated with the compound of the formula (1) and insulating fine particles surface-treated with the compound of the formula (1). Is a functional group for bonding R _a —Si— to the surface of the fine particles, and is not particularly limited as long as it is a hydrolyzable group. -3 alkoxy groups) and halogen atoms (fluorine atoms, chlorine atoms, oxalic atoms, etc.). X of the compound of the formula (1) includes an alkoxy group typified by a methoxy group and an ethoxy group, a chloro group, and the like, and any compound having a hydrolyzable group can be used. Among these, an alkoxy group is particularly preferable. This is because the alkoxy group has a high reactivity and can be processed more efficiently when the fine particles are subjected to a coupling treatment.

  Specific examples of the compound according to the above formula (1) are shown below.

  In the structure of (i), wherein the surface layer contains the compound of the formula (1), the compound of the formula (1) is 1 to 30% by mass, preferably 5 to 20% by mass with respect to the total mass of the surface layer. % Is preferable. When the compound of the formula (1) is included in the surface layer in the above range, the image unevenness caused by the charging member can be extremely effectively suppressed, and the compound of the formula (1) is applied to the charged body. Almost no migration to the charged body is observed.

Conductive fine particles The conductive fine particles contained in the surface layer according to the present invention preferably have a volume resistivity of less than 1 × 10 ¹⁰ Ω · cm.

  Specifically, examples of the conductive fine particles include metal oxide-based conductive fine particles, metal-based conductive fine particles, carbon black, carbon-based conductive fine particles, and the like, which are used alone or in combination of two or more. be able to.

Examples of the metal oxide conductive fine particles include zinc oxide, tin oxide, indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.), iron oxide, and the like. Some of the metal oxide-based fine particles exhibit sufficient electrical conductivity by themselves, but others do not. In order to make the conductivity of the fine particles sufficient, that is, to make the volume resistivity of the fine particles less than 1 × 10 ¹⁰ Ω · cm, a dopant may be added to these fine particles. In general, metal oxide fine particles are considered to exhibit conductivity by generating surplus electrons due to the presence of lattice defects, and formation of lattice defects is promoted by addition of a dopant, and sufficient conductivity can be obtained. For example, aluminum is used as a dopant for zinc oxide, antimony is used as a dopant for tin oxide, and tin is used as a dopant for indium oxide. Moreover, when obtaining the electroconductivity of titanium oxide, what coated electroconductive tin oxide on titanium oxide etc. can be mentioned.

  Examples of the metal conductive fine particles include fine particles of silver, copper, nickel, zinc and the like.

  Examples of carbon black include acetylene black, furnace black, and channel black.

  Examples of the carbon conductive fine particles include graphite, carbon fiber, activated carbon, charcoal and the like.

  Among these, it is particularly preferable to use metal oxide conductive fine particles as the conductive fine particles. The fine particles have an advantage of good dispersibility with respect to a binding material such as a resin and an advantage of being easily adjusted to a desired resistance. Among these, it is more preferable to use tin oxide or titanium oxide.

  The average particle size of the conductive fine particles is 0.001 μm to 2 μm, more preferably 0.005 to 0.5 μm. By using the conductive fine particles within this range, a coating layer having a desired resistance value and little resistance unevenness can be easily obtained. A method for measuring the average particle diameter will be described later.

-Surface-treated fine particles The conductive fine particles surface-treated with the compound represented by the formula (1) in the surface layer according to the configuration of (ii) will be described. First, examples of the conductive fine particles to be surface-treated include those described above. When surface-treating the surface layer with the compound represented by the formula (1), it is preferable to use 5 to 30% by mass of the compound of the formula (1) based on the mass of the fine particles to be surface-treated. . That is, it means that surface treatment is performed using 5 to 30 g of the compound of the formula (1) with respect to 100 g of the fine particles, whereby the conductive fine particles can be surface-treated efficiently.

  As a surface treatment method for the conductive fine particles, the fine particles and the compound of the formula (1) are mixed and dispersed in an appropriate solvent, and the coupling agent represented by the formula (1) is adhered to the surface of the fine particles. As a dispersion means, a normal dispersion means such as a ball mill or a sand mill can be used. Next, the solvent is removed from the dispersion solution, and the compound of the formula (1) is fixed on the surface of the fine particles. Moreover, you may heat-process further after this as needed. Further, a catalyst for promoting the reaction can be added to the treatment liquid. Furthermore, if necessary, the fine particles after the surface treatment may be further pulverized.

Insulating fine particles The insulating fine particles surface-treated with the compound represented by the formula (1) in the surface layer according to the configuration (ii) will be described. Here, the insulating fine particles preferably have a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more. By mixing the conductive fine particles and the insulating fine particles, the conductivity of the surface layer can be further stabilized. The insulating fine particles can also be surface-treated with the compound of the formula (1), so that the environmental stability of the charging member can be further improved. As a result, a more stable supply of an electrophotographic image without unevenness is possible. The surface treatment method and the surface treatment amount of the insulating fine particles with the compound of the formula (1) may be the same as the surface treatment of the conductive fine particles. In addition, each surface treatment coupling agent of electroconductive fine particles and insulating fine particles may mutually be the same, or may differ.

  Specific examples of the insulating fine particles include, for example, silica, alumina, titanium oxide (titanium dioxide, titanium monoxide, etc.), metal oxide-based insulating fine particles such as zinc oxide, magnesium oxide, zirconium oxide, barium sulfate, titanium. Barium acid, molybdenum disulfide, calcium carbonate, magnesium carbonate, dolomite, talc, kaolin clay, mica, aluminum hydroxide, magnesium hydroxide, zeolite, wollastonite, diatomaceous earth, glass beads, bentonite, montmorillonite, asbestos, hollow Examples thereof include fine particles such as glass spheres, graphite, rice husks, organometallic compounds, and organometallic salts. Also, known resins such as polyamide resin, silicone resin, fluororesin, (meth) acrylic resin, styrene resin, phenol resin, polyester resin, resin, urethane resin, olefin resin, epoxy resin, and copolymers thereof Fine particles such as modified products and derivatives can also be used.

  Among these, it is particularly preferable to use metal oxide insulating fine particles or resin fine particles from the viewpoint of dispersibility with respect to a binding material such as a resin. Among the metal oxide fine particles, it is particularly preferable to use titanium oxide. Titanium dioxide has a characteristic that it has a large dielectric constant and can easily control the capacitance required for the charging member.

  When conductive fine particles and insulating fine particles are used in combination, the fine particles are unified with metal oxide fine particles, or the insulating fine particles to be added are resin fine particles having a chemical bond portion similar to the binder resin. It can be said that it is more preferable to add a material similar in terms of controlling dispersibility. Further, the average particle diameter of the insulating fine particles is preferably 0.001 to 2 μm, particularly preferably 0.005 to 0.5 μm, for the same reason as the conductive fine particles.

-Binder As the binder for the surface layer, any resin and elastomer may be used. Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC), olefin-ethylene-butylene-olefin copolymer (CEBC), etc. Is mentioned. Examples of elastomers include synthetic rubbers and thermoplastic elastomers. Examples of synthetic rubbers include natural rubber (such as vulcanization treatment), EPDM, SBR, silicone rubber, urethane rubber, IR, BR, NBR, CR, and the like. Is mentioned. As thermoplastic elastomers, polyolefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene Examples thereof include a vinyl acetate-based thermoplastic elastomer, a polyvinyl chloride-based thermoplastic elastomer, and a chlorinated polyethylene-based thermoplastic elastomer. These materials may be used alone or in combination of two or more, and may be a copolymer. Since the surface layer 2d constitutes the outermost surface of the charging member and comes into contact with the photosensitive member that is a charged body, it is not preferable for the material to contaminate the photosensitive member. Moreover, it can be said that the thing with surface releasability is preferable. Therefore, it can be said that it is preferable to use a resin as the surface layer material.

  By the way, the surface layer may contain a releasable substance. By including a releasable substance, it is possible to reduce the coefficient of friction of the surface layer, so that dirt adhesion on the surface of the charging member can be reduced, durability is improved, and relative movement between the photosensitive member and the charging member is reduced. As it becomes smooth, it reduces the appearance of irregular moving states such as stick-slip, and as a result, various phenomena that may be caused by rotation unevenness such as occurrence of noise and irregular wear of the charging member surface are eliminated. Can be improved. Further, when the releasable substance is a liquid, it acts as a smoothing agent (leveling agent) when forming the surface layer of the charging member, so that the surface layer can be formed smoothly and smoothly. There are various types of releasable substances and there are various ways of classification, but from the viewpoint of function, there are many that use low surface energy and those that use slidability. Moreover, the property may be liquid or solid. For example, a solid and slidable material is generally known as a solid lubricant, for example, a substance described in a solid lubrication handbook (publishing office; second edition published on March 15, 1982) Specifically, metal oxides such as graphite, graphite fluoride, molybdenum disulfide, tungsten disulfide, boron nitride, and lead monoxide can be used.

  In addition, a compound containing silicon or fluorine in the molecule is used in an oily state or a solid state (a release resin or powder, or a part of the polymer having a release property introduced therein). Furthermore, waxes and higher fatty acids (including salts, esters and other derivatives thereof) can also be mentioned.

  The elastic layer 2b used in the present embodiment has appropriate conductivity and elasticity in order to supply power to the photosensitive member 1 as a member to be charged and to ensure good uniform adhesion of the charging member to the photosensitive member. Is. The contact angle of the surface layer forming the outermost surface of the charging member is preferably 100 ° or more. Thereby, further suppression of image unevenness is possible. The contact angle is measured by dropping pure water on the surface of the charging member using a contact angle meter CA-X manufactured by Kyowa Interface Science Co., Ltd.

-Elastic layer As a material of the elastic layer 2b used for the charging member according to the present invention, any material may be used as long as it is an elastomer such as a synthetic rubber and a thermoplastic elastomer. As for the elastomer, the same elastomer as described in the surface layer can be used.

  Moreover, you may use the foam which carried out the foam molding of these elastic materials as an elastic material. Preferably, it can be said that a synthetic rubber material is used as the elastic layer material in order to secure a nip between the charging member and the photosensitive member.

The conductivity of the elastic layer 2b is adjusted to less than 10 ⁸ Ω · cm by appropriately adding a conductive agent such as carbon black, conductive metal oxide, alkali metal salt, and ammonium salt into the elastic material. It is preferable. If the conductivity of the elastic layer 2b is 10 ⁸ Ω · cm or more, the charging ability of the charging member will be low, and it will not be possible to satisfy the charging uniformity that charges the object to be charged uniformly. In this case, the charging member periodic longitudinal unevenness often causes an image defect. Further, the elasticity and hardness of the elastic layer 2b are adjusted by adding softening oil, plasticizer, etc. and foaming the elastic material.

  As a method for controlling the surface state of the elastic layer, it is preferable to use the mechanical polishing described above. More preferably, it can be said that a method of polishing with a grindstone is preferable. In general, a method of polishing a roller-shaped elastic body is a polishing method called a traverse method. In this method, a roller is polished by moving a short grindstone according to the roller. On the other hand, there is a polishing method called a wide polishing method. This method is a method in which roller grinding can be performed in a short time by using a whetstone that is literally wide, that is, a whetstone having a width approximately equal to the length of the roller, and pressing it once.

  Since polishing is possible at a time, an elastic layer having a desired surface roughness can be easily created by controlling the shape of the grindstone. In view of work efficiency and the like, it can be said that the wide polishing method is more preferable.

  In the wide polishing method, it is preferable to perform an oscillating polishing process for the purpose of smoothing the polishing surface. This is to reciprocate the grindstone during polishing finish. The width of vibration is not particularly specified, but is about several millimeters, and preferably 50 to 60 times per minute.

-Conductive support body The conductive support body 2a used in this Embodiment can use metal materials, such as iron, copper, stainless steel, aluminum, and nickel. Furthermore, these metal surfaces may be plated for the purpose of imparting scratch resistance, but it is necessary that the conductivity is not impaired.

-About other aspects as a charging member;
Other aspects of the charging member according to the present invention are shown in FIGS. In FIG. 2, the coating layer has a three-layer structure including an elastic layer 2b, a surface layer 2d, and a resistance layer 2c therebetween. In FIG. 3, it has a four-layered coating layer in which a second resistance layer 2e is provided between the resistance layer 2c and the surface layer 2d. Further, a structure in which four or more layers are formed on the conductive substrate 2a by providing a resistance layer may be used. Further, as shown in FIG. 4, it may be a single layer structure in which only the surface layer 2d is provided on the conductive substrate 2a. Furthermore, the charging member according to the present invention is not limited to the roller shape, and may be a sheet or plate as shown in FIGS. 5 to 6, and as shown in FIGS. In addition, various shapes such as a belt shape or a film shape can be used, and the above-described layer configuration can be adopted for each of them.

  In addition, the charging roller 2 in the form of a roller has a shape in which the central portion is thickest by polishing the elastic layer 2b and becomes thinner toward both ends in order to ensure uniform adhesion between the charging roller 2 and the photoreceptor 1. It is preferable to form a so-called crown shape. The charging roller generally used has a predetermined pressing force applied to both ends of the conductive support 2a and comes into contact with the photosensitive member 1. Therefore, the pressing force at the central portion is small, and the both ends are larger. If the straightness of the charging roller is sufficient, there is no problem, but if it is not sufficient, density unevenness may occur in the images corresponding to the center and both ends. The crown shape is formed to prevent this.

Resistance layer The charging member of the present embodiment includes a resistance layer at a position in contact with the elastic layer 2b for the purpose of preventing bleeding out of the charging member such as softening oil and plasticizer contained in the elastic layer. 2c can be provided. As the material constituting the resistance layer 2c, the same material as that used for the elastic layer 2b can be used. The resistance layer 2c preferably has conductivity or semiconductivity. As the conductive material, various conductive fine particles listed for the surface layer 2d can be used. In this case, in order to obtain a desired volume resistivity, two or more kinds of the various conductive fine particles may be used in combination.

The volume resistivity of the surface layer 2d is preferably larger than the volume resistivity of the elastic layer and adjusted to 10 ¹⁶ Ω · cm or less. If the volume resistivity of the surface layer 2d is smaller than that of the elastic layer, leakage due to pinholes and scratches on the surface of the member to be charged cannot be prevented, and if it exceeds 10 ¹⁶ Ω · cm, the charging ability of the charging roller Becomes lower and charging uniformity cannot be satisfied.

  It is preferable from the viewpoint of charging uniformity that the volume resistivity of the resistance layer 2c is adjusted to be equal to or lower than the volume resistivity of the surface layer 2d and equal to or higher than the volume resistivity of the elastic layer 2b.

  For the elastic layer 2b, the surface layer 2d, and the resistance layer 2c, in addition to the various materials described above, materials having other functions can be appropriately used. Examples of such other materials include anti-aging agents such as 2-mercaptobenzimidazole, lubricants represented by stearic acid and zinc stearate, and the like in the elastic layer 2b.

  The elastic layer, the surface layer, and the resistance layer may be subjected to a surface treatment. Examples of the surface treatment include surface processing using UV and electron beams, and surface modification treatment for attaching and impregnating a compound or the like on the surface.

Measurement method of volume resistivity The conductivity (volume resistivity) of the elastic layer 2b, the surface layer 2d and the resistance layer 2c is measured by, for example, a resistance measuring device (insulation resistance meter Hiresta-UP manufactured by Mitsubishi Chemical Corporation). ). More specifically, in the elastic layer 2b, the elastic layer material itself is formed into a thickness of 2 mm, and the conductivity is measured by applying a voltage of 250 V for 30 seconds in an environment of a temperature of 23 ° C. and a humidity of 50%. In the surface layer 2d and the resistance layer 2c, the same binder resin as that forming each layer is made into a paint, the clear paint is coated on an aluminum sheet, and the conductivity of each layer is measured under the above conditions. To do.

-Formation method of each layer The production of the elastic layer 2b, the surface layer 2d, and the resistance layer 2c is not particularly limited as long as it is a suitable method for forming each layer to a suitable layer thickness. Can be prepared using a known method. These layers may be produced by, for example, adhering or covering a sheet-like or tube-like layer formed in advance with a predetermined thickness, or conventionally known such as electrostatic spraying or dipping coating. You may carry out by a construction method or according to it. Moreover, after forming a rough layer by extrusion molding, a method of adjusting the shape by polishing or the like may be used, or a method of curing and molding a material into a predetermined shape in a mold may be used.

  When using electrostatic spraying or dipping coating, various solvents are often used. Although there is no restriction | limiting in particular as a solvent to be used, It is necessary to use the solvent in which the high molecular compound to be used is easy to melt | dissolve. Specifically, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, dimethyl sulfoxide and the like Sulfoxides, ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, ethylene chloride, dichloroethylene, carbon tetrachloride and trichloroethylene, or Aromatic compounds such as benzene, toluene, xylene, ligroin, chlorobenzene and dichlorobenzene are used.

-Layer thicknesses The layer thicknesses of the elastic layer 2b, the surface layer 2d, and the resistance layer 2c are not particularly limited as long as they do not impair the function of each layer. The above is preferable. By setting it within this range, the elastic layer can retain an appropriate elasticity, and the contact with the member to be charged can be sufficient to satisfy the charging uniformity.

  Further, if the surface layer and the resistance layer are 1 μm to 1000 μm, preferably 5 to 30 μm, the layer thickness is less likely to be uneven, and the unevenness of the elastic layer appears on the surface of the charging member as it is. Can be avoided. In addition, the elastic layer can retain an appropriate elasticity, can be brought into proper contact with the member to be charged, and charging uniformity can be sufficiently satisfied.

  In the present invention, the thicknesses of the elastic layer 2b, the surface layer 2d, and the resistance layer 2c are determined by observing the layer cross section with an optical microscope or an electron microscope and measuring the layer thickness. Specifically, the roller is cut with a cutter knife or the like, the cut portion is observed with an optical or electron microscope, and the thickness of each layer is measured.

-Measuring method of fine particle diameter The particle diameter of the fine particles used in the present invention is measured using a laser diffraction particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation. First, a solution is prepared by adding a small amount of 0.2% by mass of a surfactant to distilled water. The surfactant is not particularly limited, and any commercially available surfactant can be used. This solution is put into a glass bottle, a small amount of fine particles are added, and dispersed by applying ultrasonic waves for about 5 minutes. This solution is put into a measurement cell and measured. Thereby, the particle size distribution of the fine particles can be measured. The range of the particle size that can be measured is 0.015 to 500 μm. In addition, the average particle diameter of the fine particles in the present invention is the average particle diameter of the present invention, which is the volume average particle diameter measured by the above apparatus.
・ Method of measuring volume resistivity of fine particles Furthermore, the volume resistivity of fine particles used in the present invention is a value measured by connecting MCP-PD41 (all manufactured by Mitsubishi Chemical Corporation) to Loresta-GP or Hiresta-UP. The volume resistivity of the fine particles was used. The amount of sample is preferably adjusted as appropriate according to the density of the fine particles. For example, tin oxide was 1.5 g, carbon black was 0.5 g, and the applied pressure was a constant 10.1 Mpa (102 kgf / cm ² ). The applied voltage is fixed at 10V when measured by Loresta-GP, and when measured by Hiresta-UP, the resistance area to be measured differs depending on the applied voltage. Changed.

  Subsequently, schematic configurations of the process cartridge and the electrophotographic apparatus of the present invention will be described.

Electrophotographic apparatus FIG. 9 is a diagram showing an example of a schematic configuration of the electrophotographic apparatus of the present invention.

  In this method, a toner image of each color is formed on each of a plurality of photoconductors by a developing device of each color, and the toner images of each color are sequentially transferred from each photoconductor onto an intermediate transfer member, and then transferred to an intermediate. This is an electrophotographic apparatus of a type in which multicolor toner images on a transfer body are collectively transferred to a recording medium (transfer material).

  As described above, the colorization of electrophotographic apparatuses is progressing rapidly, and the opportunity to output color images and graphic images from computers not only at the office but also at the individual level is increasing. As an electrophotographic system corresponding to this, there can be mentioned various systems as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-201912.

  Among these, the in-line method is superior from the viewpoint of speeding up in conjunction with recent market needs, and the intermediate transfer member method from the viewpoint of being compatible with various transfer materials such as cardboard and glossy paper. Can be said to be superior, but is not limited to this.

  As shown in FIG. 9, photosensitive drums 1 a to 1 d are arranged in parallel in the moving direction of the intermediate transfer belt 6 so as to be opposed to developing means 4 a to 4 d such as a developing unit containing toner of each color. Each color toner image formed on each photosensitive drum by each developing means is transferred onto the intermediate transfer member by the transfer rollers 8a to 8d in an electrostatic sequential manner, and is a four color toner in which black is added to yellow, magenta and cyan. A full color toner image is formed.

  Further, charging means 2a ′ to 2d ′, exposure means 3a to 3d, and developing means 4a to 4d for forming toner images of the respective colors on the photosensitive drums are arranged around the photosensitive drums 1a to 1d. Has been.

  Further, cleaning devices 5a to 5d having cleaning blades are provided for transferring the toner image onto the intermediate transfer belt and then collecting the toner remaining on each photosensitive drum by sliding.

  Next, an image forming operation will be described. A laser beam modulated in accordance with image data from a host such as a personal computer is exposed on the surfaces of the photosensitive drums 1a to 1d uniformly charged by the charging rollers as the charging units 2a 'to 2d'. The desired electrostatic latent image is obtained for each color. The latent image is reversely developed at the developing position and visualized as a toner image by developing means 4a to 4d which are developing units containing toner of respective colors arranged opposite to the latent image. The toner image is sequentially transferred to the intermediate transfer belt 6 at each transfer position, is fed at a predetermined timing by a sheet feeding unit (not shown), and is collectively transferred to a transfer material P conveyed by the conveyance unit. . The color toner image on the transfer material P is heated and melted by a fixing device (not shown), and is permanently fixed on a transfer medium to obtain a desired color print image.

  Here, conventionally, in order to improve the transfer efficiency of the toner image from the photosensitive drum to the intermediate transfer belt, there is a speed difference between the peripheral speed of the photosensitive drum and the peripheral speed of the intermediate transfer belt at each transfer position. Has been proposed. According to this, the transfer efficiency of each color toner image is improved, which is a very effective method when two or more color toner images are transferred in a superimposed manner. In particular, in the four-color full color mode, a toner image transferred from each photosensitive drum to the intermediate transfer belt is lost due to a difference in speed between each photosensitive drum and the intermediate transfer belt. By preventing the phenomenon and improving the transfer efficiency, it is possible to obtain a good image having no hue variation.

  More specifically, the electrophotographic photoreceptor 1 is rotationally driven at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow in the drawing. Process speed is variable. As the electrophotographic photosensitive member 1, for example, a known electrophotographic photosensitive member having a cylindrical support having conductivity and a photosensitive layer containing an inorganic photosensitive material or an organic photosensitive material on the support is used. That's fine.

  In addition, the electrophotographic photosensitive member 1 may further include a charge injection layer for charging the surface of the electrophotographic photosensitive member to a predetermined polarity and potential.

  The charging member 2 'is a charging roller in FIG. The charging roller 2 ′ is brought into contact with the electrophotographic photosensitive member 1 with a predetermined pressing force, and is driven to rotate in the forward direction with respect to the rotation of the electrophotographic photosensitive member 1 in this apparatus. Only a predetermined DC voltage (−1050 V in this example) is applied from the charging bias application power source to the charging roller 2 ′, so that the surface of the electrophotographic photosensitive member 1 has a predetermined polarity potential (a dark part in this example). (Electric potential -450V) is uniformly charged.

  A known means can be used as the exposure means 3, and examples thereof include a laser beam scanner. The exposure unit 3 performs image exposure corresponding to target image information on the charged surface of the electrophotographic photosensitive member 1, so that the potential of the exposed bright portion of the charged surface of the electrophotographic photosensitive member (in this example, bright portion potential − 100V) is selectively reduced (attenuated), and an electrostatic latent image is formed on the electrophotographic photosensitive member 1.

  As the developing unit 4, a known unit can be used. For example, the developing unit 4 of the present example includes a toner carrying member that is disposed in an opening of a developing container that contains toner and carries and conveys toner, and a housing. And a toner regulating member that regulates the toner carrying amount (toner layer thickness) of the toner carrying member. The developing means 4 is a toner (negative toner) in which the exposed portion of the electrostatic latent image on the surface of the electrophotographic photosensitive member 1 is charged to the same polarity as the charging polarity of the electrophotographic photosensitive member 1 (development bias −350 V in this example). ) Is selectively attached to visualize the electrostatic latent image as a toner image. There is no restriction | limiting in particular as a image development system, The existing method can be used. Examples of the existing method include a jumping development method, a contact development method, and a magnetic brush method. In particular, in a full-color electrophotographic apparatus that outputs a full-color image, contact development is performed for the purpose of improving toner scattering properties. The method is preferred. As the toner carrier used in the contact development method, it is preferable to use a compound having elasticity such as rubber from the viewpoint of ensuring contact stability. For example, there may be mentioned a developing roller in which an elastic layer imparted with conductivity is provided on a support such as metal. For this elastic layer, a foam obtained by foam-molding an elastic material may be used as the elastic material. Further, a layer may be provided thereon or a surface treatment may be performed. Examples of the surface treatment include a surface processing treatment using ultraviolet rays and an electron beam, and a surface modification treatment for attaching and impregnating a compound or the like to the surface.

  Reference numeral 6 denotes an intermediate transfer belt. A known means can be used for the intermediate transfer belt, and examples thereof include a conductive belt prepared by containing conductive fine particles in a resin and an elastomer material to have a medium resistance. 7 is a driving roller, and 9 is a driven roller.

  Reference numeral 8 denotes a transfer roller as transfer means. For the transfer roller 8, a known means can be used. For example, a transfer roller formed by coating an elastic resin layer having a medium resistance on a support such as metal can be exemplified. The transfer 8 is brought into contact with the electrophotographic photosensitive member 1 with a predetermined pressing force via an intermediate transfer belt to form a transfer nip portion. The electrophotographic photosensitive member 1 is rotated in the forward direction with the rotation of the electrophotographic photosensitive member 1. It rotates at the same peripheral speed as Further, a transfer voltage having a polarity opposite to the charging characteristics of the toner is applied from a transfer bias application power source.

  Residues on the electrophotographic photosensitive member 1 such as transfer residual toner are collected from the electrophotographic photosensitive member by a cleaning means 5 such as a blade type. Thereafter, charging is again performed by the charging roller 2 ′, and image formation is repeatedly performed.

  In the electrophotographic apparatus of this example, the electrophotographic photosensitive member 1 and the charging roller 2 ′ are integrally supported by a supporting member such as a resin molded body, and the electrophotographic apparatus main body can be freely attached to and detached from this integral structure. An apparatus having a process cartridge (not shown) configured as described above may be used. In addition to the electrophotographic photoreceptor 1 and the charging roller 2 ', a process cartridge that integrally supports the developing means 4 and the cleaning means may be used.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Reference Example 1)
A charging member was produced as follows.

  I: Formation of elastic layer

・ Epichlorohydrin rubber terpolymer (epichlorohydrin: ethylene oxide:
Allyl glycidyl ether = 40 mol%: 56 mol%: 4 mol%):
100 parts by mass-Light calcium carbonate: 45 parts by mass-Aliphatic polyester plasticizer: 10 parts by mass-Zinc stearate: 1 part by mass-Anti-aging agent MB (2-mercaptobenzimidazole): 0.5 parts by mass-Oxidation Zinc: 5 parts by mass-Quaternary ammonium salt (structure represented by the following formula): 2 parts by mass

  The above materials were kneaded for 10 minutes in a closed mixer adjusted to 50 ° C. to prepare a raw material compound. In this compound, 100 parts by mass of raw material epichlorohydrin rubber, 1 part by mass of sulfur as a vulcanizing agent, 1 part by mass of DM (dibenzothiazyl sulfide) as a vulcanization accelerator and TS (tetramethylthiuram monosulfide) 0.5 parts by mass was added and kneaded for 10 minutes in a two-roll mill cooled to 20 ° C. The resulting compound is formed on a 6 mm stainless steel core with an extrusion molding machine so as to form a roller with an outer diameter of 12 mm, heated and steam vulcanized, and then widened so that the outer diameter becomes 8.5 mm. Polishing was performed by a polishing method to obtain an elastic layer. The roller length was 230 mm.

II: Formation of coating layer (surface layer) The surface layer 2d was formed on the elastic layer.

  First, the conductive tin oxide fine particles were subjected to a coupling treatment according to the following procedure. After mixing the following materials with a stirrer for 30 minutes, using a bead mill disperser filled with 80% of the above dispersive medium using glass beads (average particle size: 0.8 mm) as a dispersive medium, disperse in this disperser for 10 hours. To prepare a slurry.

• Conductive tin oxide fine particles (average particle size 0.03 μm, volume resistivity 10 Ω · cm) 100 parts by mass • Compound represented by the formula (1) (see Table 2 below) 11 parts by mass • Isopropyl alcohol 500 parts by mass

  In this invention, the ratio of the coupling process in this case is 11 mass%. Using a kneader, the slurry was subjected to vacuum distillation (bath temperature: 110 ° C., product temperature: 30-60 ° C., degree of vacuum: about 100 Torr), and the surface treatment agent was baked at 120 ° C. for 2 hours. It was. The powder after baking was cooled to room temperature and then pulverized using a pin mill. Then, the heat processing for 2 hours were further performed at 150 degreeC.

In addition, titanium dioxide fine particles (average particle size: 0.041 μm, volume resistivity: 10 ¹⁶ Ω · cm) were prepared as insulating fine particles.

  Next, the surface layer 2d formed on the elastic layer will be described. The surface layer 2d was formed by coating the following surface layer coating solution by dipping. The number of dipping was 2 times.

  First, the following materials were mixed as a dipping coating solution to prepare a mixed solution.

-Caprolactone-modified acrylic polyol solution 100 parts by mass-Methyl isobutyl ketone 250 parts by mass-Conductive tin oxide (volume resistivity: 10 ³ Ω-cm) 170 parts by mass-Titanium dioxide (volume resistivity: 10 ¹⁶ Ω-cm ) 24 parts by mass • Modified dimethyl silicone oil 0.08 parts by mass • PMMA particles (average particle size: 5.1 μm, volume resistivity 10 ¹⁶ Ω · c) 60 parts by mass

  This mixed solution is mixed for 30 minutes with a stirrer, and then dispersed with glass beads (average particle size: 0.8 mm) as a dispersion medium using a bead mill disperser filled with 80% of the dispersion medium for 18 hours. did. Add a mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) 1: 1 butanone oxime block to the dispersion so that NCO / OH = 1.0 and stir for 1 hour for dipping. A coating solution was prepared.

  The surface layer coating solution was coated twice on the surface of the elastic layer by dipping. The pulling speed was fixed at 7 mm / s. First, after coating the dipping coating solution, it was air-dried at room temperature for 10 to 30 minutes, the roller was inverted, and the coating solution was coated again in the same manner. Thereafter, it was air-dried at room temperature for 30 minutes or more, and subsequently dried at 160 ° C. for 1 hour in a hot air circulating dryer. The layer thickness of the surface layer after drying was 15 μm.

-Measurement of charging member contact angle The contact angle of the surface layer was measured by the measurement method described above. The results are shown in Table 4.

-Image unevenness evaluation after leaving in a high-temperature and high-humidity environment The following procedure was used to evaluate image unevenness using the charging member.

  The charging member according to this embodiment is incorporated as a charging roller in a process cartridge in which an electrophotographic photosensitive member, a charging member, a cleaning unit, and a developing unit are integrally supported by a resin molded body, and a plastic bag or a cardboard box is used. Packed. For the toner, four colors of yellow, magenta, cyan, and black are input, and evaluation is performed using four cartridges. The process cartridge was left in a temperature 40 ° C. and humidity 95% environment for 1 month. Thereafter, the process cartridge is taken out and left in a temperature 23 ° C./humidity 50% environment for 4 hours. Then, the process cartridge is assembled in the electrophotographic apparatus having the configuration shown in FIG. The charged photoconductor was developed without exposure and a halftone image was output, and image density unevenness was visually evaluated, thereby evaluating the degree of charge unevenness during primary charging. In the case of yellow toner, it is difficult to evaluate image density unevenness, so that an image was output with black toner only at the time of evaluation. A voltage of −1050 V was applied to the charging member. A photoconductor having a diameter of 24 mm was used. As the developing means of the process cartridge used in this evaluation, the one having the above-described roller-shaped toner carrier (developing roller), a stirring member for stirring the toner, and a toner regulating member was used. A blade-type cleaning blade was used as the cleaning means.

  The image levels in the table are evaluated in four stages according to the following criteria.

Rank 1: Image unevenness is not recognized at all.
Rank 2: Image unevenness is slightly recognized at the edge of the image.
Rank 3: Although slight unevenness is recognized in the center of the image, it is within the allowable range.
Rank 4: Unevenness is noticeable throughout the image

  As a result, as shown in Table 4 below, the charging member of this reference example was incorporated into the process cartridge according to this reference example, and after storage for a long time under high temperature and high humidity conditions, noticeable unevenness occurred in the entire electrophotographic image. It was something to let me.

Example 1
A charging member was produced in the same manner as in Reference Example 1 except that the titanium dioxide fine particles as insulating fine particles were subjected to a coupling treatment. The coupling treatment of the titanium dioxide fine particles was performed in the same manner as the coupling treatment of the conductive tin oxide fine particles in Reference Example 1 except that the ratio of the coupling treatment was changed to 10% by mass. The contact angle of this charging member was measured in the same manner as in Reference Example 1.

  Further, this charging member is incorporated as a charging roller in a process cartridge made of the same member as in Reference Example 1. After packing this process cartridge in the same manner as in Reference Example 1, the charging member is placed in an environment with a temperature of 40 ° C. and a humidity of 95%. Left for months. Next, the process cartridge is taken out of the package, mounted in the electrophotographic apparatus main body in the same manner as in Reference Example 1, image formation is performed, and the obtained electrophotographic image is evaluated according to the same criteria as in Reference Example 1. did. As a result, as shown in Table 4, no noticeable unevenness was observed over the entire electrophotographic image observed in Reference Example 1, and an extremely high quality electrophotographic image was obtained. From this result, the effect of the surface treatment with the compound of the formula (1) on the insulating fine particles in the surface layer of the charging member is clear.

(Example 2)
A charging member was prepared in the same manner as in Example 1 except that the titanium dioxide fine particles were treated with the insulating particle surface treatment coupling agent and the treatment amount shown in Table 2 below. The layer thickness of the surface layer was 13.3 μm. The contact angle of the surface layer of the charging member thus obtained and image unevenness evaluation after being left in a high-temperature and high-humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 3)
The surface treatment coupling agent for the tin oxide fine particles, the surface treatment coupling agent for the titanium dioxide fine particles, and the amount treated by them were changed as shown in Table 2, and the silica particles (average particle size: 0.05 μm, A charging member was produced in the same manner as in Example 1 except that 10 parts by mass of volume resistivity: 10 ¹⁶ Ω · cm) was added. The surface layer thickness was 25 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 4)
A charging member was prepared in the same manner as in Example 1 except that the surface coupling agent for the tin oxide fine particles, the surface treatment coupling agent for the titanium dioxide fine particles, and the treatment amount thereof were changed as shown in Table 2. The surface layer thickness was 12 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 5)
The tin oxide fine particles are replaced with carbon black fine particles (average particle size volume resistance 0.15 μm, volume resistance 0.1 Ω · cm), surface treatment coupling agent for the carbon black fine particles, surface treatment coupling agent for titanium dioxide fine particles, and A charging member was prepared in the same manner as in Example 1 except that the treatment amount by them was changed as shown in Table 2. The surface layer thickness was 23.2 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Examples 6 to 10)
A charging member was prepared in the same manner as in Example 1 except that the surface treatment coupling agent for the tin oxide fine particles, the surface treatment coupling agent for the titanium dioxide fine particles, and the treatment amount thereof were changed as shown in Table 2. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4. Table 4 also shows the film thickness of the surface layer of each charging member.

(Example 11)
In Example 1, the insulating fine particles were replaced with barium titanate fine particles (average particle size 0.15 μm, volume resistance 10 ¹⁵ Ω · cm), surface treatment coupling agent for tin oxide fine particles, and titanic acid as insulating particles. A charging member was prepared in the same manner as in Example 1 except that the surface treatment coupling agent for barium fine particles and the treatment amount thereof were changed as shown in Table 2. The surface layer thickness was 15.2 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Examples 12 to 14)
The charging member in the same manner as in Example 1 except that the surface treatment coupling agent for tin oxide fine particles, the surface treatment coupling agent for titanium dioxide fine particles, and the treatment amount thereof were changed as shown in Table 2. It was created. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4 below. Table 4 also shows the film thickness of the surface layer of each charging member.

(Example 15)
Example 1 except that tin oxide and titanium oxide not subjected to coupling treatment were used, and the compounds shown in Table 3 below were added to the dipping paint in the proportions shown in Table 3 below as the compounds represented by the formula (1). Similarly, a charging member was prepared. The addition amount of the compound of the present Example shows the mass% of the compound with respect to all solid content except a solvent (for example, methyl isobutyl ketone) from the dipping paint. In this example, the amount of the compound added was 5.35% by mass, and the surface layer thickness was 16.7 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 16)
A charging member was prepared in the same manner as in Example 15 except that the compound represented by the formula (1) and the addition amount thereof were changed as shown in Table 3. The surface layer thickness was 20.8 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 17)
The tin oxide fine particles were replaced with carbon black fine particles (average particle size volume resistance 0.15 μm, volume resistance 0.1 Ω · cm), and the compound represented by the formula (1) and the amount added were changed as shown in Table 3. A charging member was prepared in the same manner as in Example 15 except that. The surface layer thickness was 12.1 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Example 18)
A charging member was prepared in the same manner as in Example 15 except that the compound represented by the formula (1) and the addition amount thereof were changed as shown in Table 3. The surface layer thickness was 19.1 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

Example 19
A charging member was prepared in the same manner as in Example 15 except that the compound represented by the formula (1) and the addition amount thereof were changed as shown in Table 3. The surface layer thickness was 8.3 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Examples 1-2)
A charging member was prepared in the same manner as in Example 1 except that the surface treatment coupling agent for tin oxide fine particles and the treatment amount thereof were changed as shown in Table 2. The surface layer thickness was 21 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Example 3)
A charging member was prepared in the same manner as in Example 1 except that the titanium dioxide fine particles were not added and the amount of tin oxide fine particles coupled was changed as shown in Table 2. The surface layer thickness was 12.3 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Example 4)
A charging member was prepared in the same manner as in Example 15 except that the compound represented by the formula (1) and the addition amount thereof were changed as shown in Table 3. The surface layer thickness was 17.3 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Example 5)
In Example 15, a charging member was produced in the same manner except that the compound represented by the formula (1) was not added. The surface layer thickness was 13.8 μm. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Example 6)
The tin oxide fine particles were changed to carbon black fine particles (average particle size 0.2 μm, volume resistivity 0.05 Ω · cm) and charged in the same manner as in Example 15 except that the compound represented by the formula (1) was not added. A member was created. At this time, the thickness of the charging member surface layer was uneven, and the unevenness occurred on the image. The contact angle of the surface layer of the obtained charging member was performed in the same manner as in Reference Example 1. The results are shown in Table 4.

(Comparative Example 7)
A charging member was prepared in the same manner as in Example 8 except that the insulating particles were not subjected to surface coupling agent treatment. The contact angle of the surface layer of the obtained charging member and image unevenness evaluation after being left in a high temperature and high humidity environment were evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

Although the embodiments of the present invention have been described above, preferred embodiments of the present invention are listed as follows [Embodiment 1]
A charging member comprising a conductive support and a coating layer covering the periphery of the conductive support, the conductive surface layer constituting the outermost surface of the charging member Includes at least one selected from the following (i) and (ii):
(I) conductive fine particles and a compound represented by the following formula (1);
(Ii) Conductive fine particles whose surface is treated with a compound represented by the following formula (1) and insulating fine particles whose surface is treated with a compound represented by the following formula (1):
R _a -Si-X _4-a (1)
(In the above formula (1), a is an integer of 1 to 3, R is a branched alkyl group, and X is a hydrolyzable group).

[Embodiment 2]
The charging member according to embodiment 1, wherein in (i), the surface layer contains 1 to 30% by mass of the compound represented by the formula (1) with respect to the surface layer.

[Embodiment 3]
The charging member according to embodiment 1, wherein in (ii), the surface of the conductive fine particles is treated with a compound represented by the formula (1) at a ratio of 5 to 30% by mass.

[Embodiment 4]
The charging member according to any one of Embodiments 1 to 3, wherein in the formula (1), X is an alkoxy group.

[Embodiment 5]
The charging member according to any one of Embodiments 1 to 4, wherein the conductive fine particles are metal oxide fine particles.

[Embodiment 6]
The charging member according to embodiment 5, wherein the metal oxide is tin oxide.

[Embodiment 7]
The charging member according to embodiment 1, wherein the insulating fine particles are fine particles of titanium oxide.

[Embodiment 8]
The charging member according to any one of embodiments 1 to 7, wherein a contact angle of a surface of the charging member is 100 ° or more.

[Embodiment 9]
An electrophotographic photosensitive member as a charged body;
The charging means having the charging member according to any one of Embodiments 1 to 8 for charging the electrophotographic photosensitive member is integrally supported, and is detachable from the main body of the electrophotographic apparatus. Process cartridge.

[Embodiment 10]
The process cartridge according to embodiment 9, wherein the charging unit is disposed in contact with the electrophotographic photosensitive member.

[Embodiment 11]
An electrophotographic photosensitive member to be charged, a charging unit having the charging member according to any one of Embodiments 1 to 8, for charging the electrophotographic photosensitive member, an exposure unit, a developing unit, and a transfer unit And an electrophotographic apparatus.

[Embodiment 12]
The electrophotographic apparatus according to embodiment 11, wherein the charging means is in contact with the electrophotographic photosensitive member.

[Embodiment 13]
The electrophotographic apparatus according to embodiment 12, wherein only a DC voltage is applied to the charging member by the charging means.

It is a schematic sectional drawing which shows the one aspect | mode of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. It is a schematic sectional drawing which shows the other aspect of the charging member which concerns on this invention. 1 is a schematic configuration diagram showing an aspect of an electrophotographic apparatus according to the present invention.

Explanation of symbols

1 Electrophotographic photoreceptor 2 Charging member (charging roller)
2a support 2b elastic layer 2c resistance layer 2d surface layer 2e second resistance layer 2 'charging roller 3 image exposure means 4 developing means 5 cleaning means 6 intermediate transfer belt 8 transfer member (transfer roller)
P transfer material

Claims (13)

A charging member comprising a conductive support and a coating layer covering the periphery of the conductive support, the conductive surface layer constituting the outermost surface of the charging member Includes at least one selected from the following (i) and (ii):
(I) conductive fine particles and a compound represented by the following formula (1);
(Ii) Conductive fine particles whose surface is treated with a compound represented by the following formula (1) and insulating fine particles whose surface is treated with a compound represented by the following formula (1):
R _a -Si-X _4-a (1)
(In the above formula (1), a is an integer of 1 to 3, R is a branched alkyl group, and X is a hydrolyzable group).   The charging member according to claim 1, wherein in (i), the surface layer contains 1 to 30% by mass of the compound represented by the formula (1) with respect to the surface layer.   The charging member according to claim 1, wherein in (ii), the surface of the conductive fine particles is treated with a compound represented by the formula (1) at a ratio of 5 to 30% by mass.   The charging member according to claim 1, wherein X in the formula (1) is an alkoxy group.   The charging member according to claim 1, wherein the conductive fine particles are metal oxide fine particles.   The charging member according to claim 5, wherein the metal oxide is tin oxide.   The charging member according to claim 1, wherein the insulating fine particles are fine particles of titanium oxide.   The charging member according to claim 1, wherein a contact angle of a surface of the charging member is 100 ° or more.   An electrophotographic apparatus which integrally supports an electrophotographic photosensitive member to be charged and a charging means having a charging member according to any one of claims 1 to 8 for charging the electrophotographic photosensitive member. A process cartridge which is detachable from the main body.   The process cartridge according to claim 9, wherein the charging unit is disposed in contact with the electrophotographic photosensitive member.   An electrophotographic photosensitive member as a member to be charged, a charging unit having a charging member according to any one of claims 1 to 8, for charging the electrophotographic photosensitive member, an exposure unit, a developing unit, and a transfer unit And an electrophotographic apparatus.   The electrophotographic apparatus according to claim 11, wherein the charging unit is in contact with the electrophotographic photosensitive member.   The electrophotographic apparatus according to claim 12, wherein only a DC voltage is applied to the charging member by the charging unit.