JP2011133550A - Charging roller, process cartridge and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of a white mist-like image occurring due to peeling apart of a conductive supporting shaft and an elastic layer, and furthermore to suppress the occurrence of an image with horizontal stripes due to unevenness in charging by providing uniform conduction between the conductive supporting shaft and the elastic layer. <P>SOLUTION: The conductive roller for contact charging has an adhesive layer and the elastic layer containing epichlorohydrin rubber, formed in this order on the outer periphery of the conductive supporting shaft with a metal surface. In this case, the adhesive layer contains phenol resin and nodular graphite particles with particle diameters that are greater than the thickness of the adhesive layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging roller, a process cartridge, and an electrophotographic apparatus.

  Patent Document 1 discloses a conductive rubber roller having an elastic layer mainly composed of an epichlorohydrin rubber composition, in which a conductive support shaft and an elastic layer are bonded using an adhesive layer having a phenol resin and carbon black. Is described.

Japanese Patent Laid-Open No. 10-293440

  The inventors of the present application evaluated the conductive rubber roller according to Patent Document 1. As a result, depending on the usage environment, the conductive support shaft may corrode, which may cause swelling of the elastic layer, or the elastic layer may peel from the conductive support shaft together with the adhesive layer. Therefore, an object of the present invention is to provide a charging roller that suppresses the occurrence of corrosion on the surface of the conductive support shaft and suppresses the peeling of the elastic layer due to the corrosion in a charging roller that includes epichlorohydrin rubber in the elastic layer. It is to be. It is another object of the present invention to provide an electrophotographic apparatus and a process cartridge that can stably provide high-quality electrophotographic images even in various environments.

  The charging roller according to the present invention is a charging roller for contact charging in which at least an adhesive layer and an elastic layer containing epichlorohydrin rubber are sequentially formed on the outer periphery of a conductive support shaft whose surface is made of metal. The charging roller is characterized by containing phenolic resin and spherical graphite particles, and containing spherical graphite particles having a particle diameter larger than the thickness of the adhesive layer.

  In addition, an electrophotographic apparatus according to the present invention includes the above charging roller.

  Furthermore, a process cartridge according to the present invention includes the above-described charging roller, and is configured to be detachable from the main body of the electrophotographic apparatus.

  According to the present invention, even when epichlorohydrin rubber is used for the elastic layer, the occurrence of corrosion on the surface of the conductive support shaft can be suppressed. Therefore, peeling of the elastic layer from the conductive support shaft can be well suppressed.

It is a schematic diagram showing the state of the spherical graphite particles in the adhesive layer of the charging roller according to the present invention. It is sectional drawing of the charging roller which concerns on this invention. It is explanatory drawing of the measuring method of the electrical resistance value of a charging roller. 1 is a cross-sectional view of an electrophotographic apparatus according to the present invention. It is sectional drawing of the process cartridge which concerns on this invention.

  The inventors of the present application have made extensive studies on a mechanism in which corrosion occurs on the surface of the conductive support shaft in the roller according to Patent Document 1. In this process, when the adhesive layer existing between the conductive support shaft and the elastic layer was made of only phenol resin, the surface of the conductive support shaft did not corrode even when left in a high temperature and high humidity environment. In addition, as the amount of carbon black in the adhesive layer is increased, more corrosion occurs on the surface of the conductive support shaft. From this, it was found that the carbon black in the adhesive layer affects the ease of migration of water and halide ions. This is because carbon black forms an aggregate of fine amorphous particles in the adhesive layer, and there are minute spaces in the aggregate, so that chloride ions are conductive through the space. It was estimated that the surface of the support shaft had been reached.

  However, unless conductivity is imparted to the adhesive layer, electrical conduction from the conductive support shaft to the elastic layer cannot be ensured. Accordingly, the present inventors formed an adhesive layer using an adhesive containing large graphite particles, and formed a charging roller having a configuration in which the graphite particles entered the elastic layer side as shown in FIG. As a result, such a charging roller has electrical continuity from the conductive support to the elastic layer, and corrodes the surface of the conductive support shaft even when placed in a high humidity environment for a long time. Has been found to hardly occur. This is because the conduction between the conductive support shaft and the elastic layer exists between the conductive support shaft and the elastic layer, unlike the conventional conductive path formed by agglomerating many carbon blacks. This is considered to be due to the movement of π electrons inside one graphite particle, and there is almost no passage for chloride ions generated in the elastic layer to reach the surface of the conductive support shaft. Although the surface of the portion of the graphite particle entering the elastic layer is covered with a thin layer of adhesive, it is extremely thin and does not hinder conduction.

  Accordingly, the charging roller according to the present invention includes a conductive support shaft whose surface is made of metal, an adhesive layer containing phenol resin formed on the peripheral surface of the conductive support shaft, and a peripheral surface of the adhesive layer. In the charging roller having an elastic layer containing epichlorohydrin rubber, graphite particles having a particle size larger than the thickness of the adhesive layer are disposed between the conductive support shaft and the elastic layer. It is what. The configuration of the charging roller according to the present invention will be described in detail below.

<Charging roller>
The charging roller of the present invention is a charging roller in which an adhesive layer and an elastic layer are sequentially formed on the outer periphery of a conductive support shaft whose surface is made of metal. The elastic layer contains epichlorohydrin rubber, and the adhesive layer contains a phenol resin and spherical graphite particles having a particle diameter larger than the thickness of the adhesive layer.

The structure of the charging roller includes a conductive support shaft, an adhesive layer, and a conductive elastic layer. A surface layer can be provided on the surface of the conductive elastic layer as necessary. 1A shows a charging roller having a conductive support shaft 1, an adhesive layer 2, and a conductive elastic layer 3. FIG. 1B shows a conductive support shaft 1, an adhesive layer 2, and a conductive elastic layer 3. A charging roller having a surface layer 4 is shown. Hereinafter, a charging roller including a conductive support shaft, an adhesive layer, an elastic layer, and a surface layer will be described.
[Conductive support shaft]
The conductive support shaft used in the charging roller of the present invention has at least a surface of conductivity and has a function of supporting an elastic layer provided on the support shaft. Examples of the material include metals such as iron, copper, stainless steel, aluminum, nickel, and alloys thereof. In addition, for the purpose of imparting scratch resistance to these surfaces, plating treatment or the like may be performed as long as the conductivity is not impaired.
[Adhesive layer]
As shown in FIG. 2, the adhesive layer is provided on the conductive support shaft, and is provided to bond the conductive support shaft and the elastic layer and to conduct the conductive support shaft and the elastic layer. It is done. The adhesive layer contains at least a phenol resin and spherical graphite particles having a particle diameter larger than the thickness of the adhesive layer.

(Phenolic resin)
As the phenol resin in the present invention, a known thermosetting phenol resin can be used.
The thermosetting phenol resin can firmly bond metal and epichlorohydrin rubber. In addition, the phenolic resin is three-dimensionally cross-linked, forms a dense network structure, and is excellent in heat resistance and water resistance, so that the migration of water and ionic substances to the conductive support shaft can be suppressed. it can. As thermosetting phenol resins, there are novolak type phenol resins and resol type phenol resins, which may be used alone or in combination.

(Graphite particles)
Graphite has an SP3 hybrid orbit and forms a hexagonal network plane by three σ (sigma) bonds, and the remaining one electron is oriented perpendicular to the network plane to form a π (pi) bond. The π electrons responsible for forming π bonds move like free electrons in the hexagonal network. As the graphite particles according to the present invention, the half-value width Δν ₁₅₈₀ of the peak intensity at ₁₅₈₀ cm ⁻¹ in the Raman spectrum is 80 cm.
^-1 or less, particularly 60 cm ^-1 or less is preferable from the viewpoint of conductivity. Specific examples of such graphite particles include the following. Particles made of artificial graphite, natural graphite particles, particles obtained by subjecting bulk mesophase pitch to graphite, particles obtained by subjecting mesocarbon microbeads to graphite treatment, particles obtained by applying mesophase to phenol resin and subjecting to graphite, Particles obtained by graphite treatment of phenol resin. Among them, particles obtained by graphite treatment of mesocarbon microbeads, particles obtained by coating phenol resin with mesophase and graphite treatment, and particles obtained by graphite treatment of phenol resin are spherical. Moreover, you may use what spheroidized the said graphite particle which is an indeterminate form. For example, as a method for spheroidizing natural graphite, it is known that spherical natural graphite particles can be obtained by rolling and circulating in a machine at a high pressure using a counter jet mill.
・ Natural graphite;
Natural graphite is produced from the ground in which the coal seam and the like have become graphite due to geothermal heat and high pressure in the ground. Such natural graphite is a dark gray to black glossy, very soft, slippery crystalline mineral with excellent properties such as heat resistance, chemical stability, lubricity, and fire resistance. It is widely used industrially in the form of powders, solids and paints for electrical materials. Some crystal structures belong to the hexagonal system and other rhombohedral systems, and have a complete layered structure.
-Particles obtained by graphite treatment of bulk mesophase pitch;
Bulk mesophase pitch can be obtained, for example, by extracting β-resin from a coal tar pitch or the like by solvent fractionation, and performing hydrogenation and heavy treatment. 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 wt% or more. When the amount less than 95 wt% is used, the inside of the particles is difficult to be liquid phase carbonized, and solid phase carbonization causes the particles to remain in a crushed state, so that a spherical shape may not be obtained. As a method of obtaining graphite particles using mesophase pitch, first, the bulk mesophase pitch is finely pulverized to 2 μm or more and 25 μm or less, and this is heat-treated in air at 200 ° C. or more and 350 ° C. or less to be lightly oxidized To do. By this oxidation treatment, the bulk mesophase pitch particles are infusible only on the surface, and melting and fusion during the graphitizing heat treatment in the next step are prevented. The oxidized bulk mesophase pitch particles suitably have an oxygen content of 5% by mass to 15% by mass. In addition, when the oxygen content is less than 5% by mass, fusion of particles during heat treatment may become intense. Moreover, when it exceeds 15 mass%, it will oxidize to the inside of a particle | grain and there may be a malfunction of being difficult to obtain a spherical thing. Next, the desired graphite particles are obtained by heat-treating the oxidized bulk mesophase pitch particles at 1000 ° C. or higher and 3500 ° C. or lower in an inert atmosphere such as nitrogen or argon.
-Particles obtained by treating graphite with mesocarbon microbeads;
As a method for obtaining mesocarbon microbeads, coal-based heavy oil or petroleum-based heavy oil is heat-treated at a temperature of 300 ° C. or higher and 500 ° C. or lower and polycondensed to produce crude mesocarbon microbeads. Thereafter, the reaction product is subjected to treatments such as filtration, stationary sedimentation, and centrifugal separation to separate mesocarbon microbeads, followed by washing with a solvent such as benzene, toluene, xylene, and the like, followed by drying. As a method of obtaining graphite particles using these mesocarbon microbeads, first, the mesocarbon microbeads after drying are mechanically dispersed primarily with a force that does not cause destruction. This is preferable in order to obtain a 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 atmosphere and carbonized. It is preferable for the carbide after the primary heat treatment to mechanically disperse the carbide with a force that does not destroy the carbide in order to prevent coalescence of the particles after the graphite treatment and to obtain a uniform particle size. The carbide that has undergone the secondary dispersion treatment is subjected to a secondary heat treatment at 1000 ° C. or more and 3500 ° C. or less in an inert atmosphere to obtain desired graphite particles.
-Particles obtained by coating phenol resin with mesophase and treating with graphite;
Examples of the phenol resin include a resol type phenol resin that is a condensate of phenol and aldehydes. The resol-type phenol resin is a resin obtained by reacting an aromatic compound having a phenolic hydroxyl group and an aldehyde under a catalyst and curing by heating. As a method of obtaining graphite particles using this phenol resin, bulk mesophase pitch is coated on the surface of the phenol resin spherical particles by a mechanochemical method. And desired graphite particle | grains are obtained by baking after heat processing by oxidizing atmosphere formation.
-Particles obtained by graphite treatment of phenol resin;
Examples of the phenol resin that is a precursor include a resol type phenol resin that is a condensate of phenol and aldehydes. The resol-type phenol resin is a resin obtained by reacting an aromatic compound having a phenolic hydroxyl group and an aldehyde under a catalyst and curing by heating. As a method for obtaining graphite particles using this phenol resin, there is a method in which the phenol resin is fired at 1000 ° C. or more and 3500 ° C. or less in an inert gas atmosphere. At this time, the flow rate of the inert gas is preferably 0.1 ml / min or more per 1 g of phenol resin. By doing in this way, a volatile matter can be efficiently removed from a phenol resin. Alternatively, the firing pressure may be a low pressure of 50 kPa or less. By baking at a pressure of 50 kPa or less, volatile components from the phenol resin can be efficiently removed from the reaction system.

<Measurement of the half-value width Δν ₁₅₈₀ of the Raman spectrum>
The graphite particles contained in the adhesive layer are measured under the following conditions using the graphite particles cut out from the adhesive layer as a measurement sample.

Measuring instrument: Raman spectrometer (trade name “LabRAM HR”, manufactured by HORIBA JOBIN YVON)
Laser: He-Ne laser (peak wavelength: 632 nm)
Filter: D0.3
Hall: 1000μm
Slit: 100 μm
Center spectrum: 1500cm ^-1
Measurement time: 1 second x 16 times Grating: 1800
Objective lens: × 50
In the above measurement, the band width at a height corresponding to ½ of the peak existing in the region from 1570 cm ⁻¹ to 1630 cm ⁻¹ derived from graphite is expressed as the half-value width Δν of the Raman spectrum.
₁₅₈₀ .

(Graphite particle size)
The particle size of the graphite particles needs to be larger than the thickness of the adhesive layer (21 in FIG. 2). This is because the presence of one graphite particle between the conductive support shaft 1 and the conductive elastic layer 3 allows the one graphite particle to conduct electricity between the conductive support shaft and the conductive elastic layer. It is to make it. This makes it difficult for chloride ions generated from the conductive elastic layer to reach the conductive support shaft and corrodes the surface of the conductive support shaft, unlike when a conductive path made of carbon black is formed in the adhesive layer. Can be suppressed very effectively.

(Circularity of graphite particles)
The circularity of the graphite particles is preferably 0.9 or more. In other words, due to the nearly spherical shape, when the adhesive layer is provided on the conductive support shaft, the conductive material is not oriented and the conduction between the conductive support shaft and the elastic layer is uniform, and resistance unevenness is small. It can be a charging roller. More preferably, the proportion of particles having a circularity of 0.9 or more in the entire spherical graphite particles contained in the adhesive layer is 80% or more.

  The particle diameter and circularity of these spherical graphite particles are calculated as follows.

(Measurement of the particle size of the graphite particles in the adhesive layer and the thickness of the adhesive layer around the particles)
An arbitrary point of the adhesive layer is cut out with a focused ion beam “FB-2000C” (trade name, manufactured by Hitachi, Ltd.) every 20 nm over 500 μm, and a cross-sectional image thereof is taken. Then, a three-dimensional particle shape and an adhesive layer shape around the three-dimensional particle are created by combining at intervals of 20 nm. This operation is performed at an arbitrary 100 points. From the three-dimensional shape obtained above, the particle diameter of the particles and the thickness of the adhesive layer are calculated.

(Circularity of spherical graphite particles in the adhesive layer)
It calculates | requires with the following formula from the said particle | grain shape.

Circularity = (peripheral length of a circle having the same area as the particle projection area) / (perimeter of the particle projection image)
Here, the “particle projected area” is the area of the binarized spherical graphite particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the graphite particle image. That's it. The circularity is 1.000 when the particle is a perfect sphere, and the more complicated the surface shape, the smaller the circularity.

The volume resistivity of the graphite particles is preferably 1 × 10 ⁻⁵ Ωcm or more and 1 × 10 ⁴ Ωcm or less. More preferably, it is 1 × 10 ⁻⁵ Ωcm or more and 1 × 10 ² Ωcm or less. By setting the volume resistivity of the spherical graphite particles in the above range, the effect of the present invention is further exhibited.

Moreover, the volume resistivity of the spherical graphite particles was 23 ° C. and 50% RH environment, and a voltage of 10 V was applied to the sample using a resistance measuring device “Loresta-GP” (trade name, manufactured by Mitsubishi Chemical Corporation). The measured value at the time. In addition, as a sample to be measured, a sample compressed by applying a pressure of 10.1 MPa (102 kgf / cm ² ) is used.

  The average particle diameter of the graphite particles themselves was determined by observing 1000 primary particles excluding secondary agglomerated particles with a transmission electron microscope (TEM), obtaining the projected area, and obtaining a circle of the obtained area. The equivalent diameter is calculated to determine the volume average particle diameter. Furthermore, the circularity of the spherical graphite particles themselves is generally used as a simple method for quantitatively expressing the shape of the particles. The particle shape is detected by a flow type particle image analyzer. From the above formula. For measurement, a flow type particle image analyzer “FPIA-1000” (trade name, manufactured by Toa Medical Electronics Co., Ltd.) is used. Even in the data measured by this apparatus, the “particle projected area” in the above formula is binarized and is the area of the spherical graphite particle image, and the “peripheral length of the particle projected image” is the spherical graphite particle image. This is the length of the contour line obtained by connecting the edge points. The circularity of the spherical graphite particles of the present invention is a value obtained by calculating the circularity of each particle and then calculating the average value of the calculated circularity by the following method. In other words, the circularity is 0.400 to 1.000, at intervals of 0.010, 0.400 or more and less than 0.410, 0.410 or more and less than 0.420, ..., 0.990 or more and less than 1.000. And 1.000 divided into 61 divided ranges. Next, the average value of the entire particles is calculated from the number of particles belonging to each division range, the division, and the median value of the division ranges. The circularity is 1.000 when the particles are perfectly spherical, and the smaller the surface shape is, the smaller the value is as described above.

  A specific method for measuring the circularity of the graphite particles is as follows. That is, 10 ml of ion-exchanged water from which impure solids were previously removed was prepared in a container, and after adding a small amount of a surfactant such as alkylbenzene sulfonate as a dispersant, 0.02 g of a measurement sample was added, Disperse uniformly. Dispersion is carried out for 5 minutes using an ultrasonic disperser “UH-50 type” (trade name, manufactured by SMT Co., Ltd.) equipped with a titanium alloy chip of φ5 mm as a vibrator. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. Then, using a flow particle image analyzer, the dispersion concentration is readjusted so that the concentration of the spherical graphite particles at the time of measurement is 3000 / μl or more and 10,000 / μl or less, and about 1000 or more spherical graphite particles are obtained. measure.

  The content of the spherical graphite particles having a particle diameter larger than the thickness of the adhesive layer is preferably 7% by volume or more and 40% by volume or less, and more preferably 10% by volume or more and 35% by volume or less with respect to the adhesive layer. By setting it as this range, the effect of this invention which balanced barrier property and electroconductivity is exhibited more.

  The adhesive layer can be formed by a coating method such as roll coating, electrostatic spray coating, or dipping coating. The solvent used in the coating solution may be any solvent that can dissolve the phenol resin. Specific examples are given below. Ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.), ethers (tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, etc.), esters (methyl acetate, ethyl acetate, etc.), aromatic compounds (xylene, ligroin, etc.). As a method for dispersing the binder, particles, and the like, known solution dispersing means such as a ball mill, a sand mill, a paint shaker, a dyno mill, and a pearl mill can be used.

[Elastic layer]
Since the charging roller of the present invention is preferably used in contact with an electrophotographic photosensitive member, it preferably has elasticity. In the present invention, the elastic layer 2 is preferably formed on the outer periphery of the conductive support shaft 1. The elastic layer 2 is made of a conductive elastic body.

The conductive elastic body is formed, for example, by dispersing a conductive agent in a polymer elastic body. As the conductive agent, the above-described ionic conductive agent or electronic conductive agent can be used. The blending amount of the conductive agent is preferably determined so that the electric resistance of the conductive elastic body is 1 × 10 ³ Ω · cm or more and 1 × 10 ⁹ Ω · cm at 23 ° C./50% RH.

  The polymer elastic body is composed of a rubber composition containing epichlorohydrin rubber.

  In the epichlorohydrin rubber, the polymer itself has conductivity in the middle resistance region, and good conductivity is exhibited even if the addition amount of the conductive agent is small. Also, variation in electrical resistance depending on the position can be reduced. Specific examples of epichlorohydrin rubber are given below. Epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, and the like. Of these, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer is particularly preferably used since it exhibits stable conductivity in a medium resistance region. The epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer can control conductivity and workability by arbitrarily adjusting the degree of polymerization and composition ratio. Further, rubber other than epichlorohydrin rubber may be contained. For example, synthetic rubbers such as acrylonitrile-butadiene rubber, chloroprene rubber, urethane rubber, and silicone rubber. Alternatively, thermoplastic elastomers such as styrene / butadiene / styrene block copolymers and styrene / ethylene butylene / styrene block copolymers may be used. In addition, plasticizers, fillers, vulcanizing agents, vulcanization accelerators, anti-aging agents, anti-scorching agents, dispersants and release agents are added to the conductive elastic body as necessary. it can.

  The elastic layer is preferably formed by a known method such as extrusion molding, injection molding, or compression molding after mixing the above-mentioned conductive elastic material with a closed mixer. The elastic layer may be produced by directly forming a conductive elastic body on a conductive support shaft provided with an adhesive layer. Alternatively, a conductive elastic body previously formed into a tube shape may be formed on the conductive support shaft. Note that the surface may be polished and the shape may be adjusted after the elastic layer is formed.

  The hardness of the elastic layer is preferably 70 ° or less, particularly 60 ° or less in terms of micro hardness (MD-1 type), since a sufficient nip width can be secured between the charging roller and the photoreceptor. In addition, "micro hardness (MD-1 type)" is the hardness measured using Asker micro rubber hardness meter MD-1 type (trade name, manufactured by Kobunshi Keiki Co., Ltd.). Specifically, the hardness meter is a value measured in a 10 N peak hold mode with respect to a charging roller left in an environment of normal temperature and normal humidity (23 ° C./55% RH) for 12 hours or more.

[Surface layer]
(Binder resin)
As the binder resin used for the surface layer of the present invention, a known binder resin can be used.

  As the resin, a resin such as a thermosetting resin or a thermoplastic resin can be used. Of these, fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, and the like are preferable. Specific examples of the synthetic rubber are given below. Ethylene-propylene-diene copolymer, styrene-butadiene rubber, silicone rubber, urethane rubber, isoprene rubber, butyl rubber, acrylonitrile-butadiene rubber, chloroprene rubber, acrylic rubber, and epichlorohydrin rubber.

(Other ingredients)
The surface layer can contain other materials as long as the effects of the present invention are not impaired. Examples of other materials include a conductive agent and a release agent. An ionic conductive agent can be used as the conductive agent. Examples of the ionic conductive agent are given below. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, calcium perchlorate, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and the like. As the release agent, those having low surface energy, those having slidability, and the like can be used. By including a release agent in the surface layer, the relative movement between the charging member and the photosensitive member becomes smooth, and the occurrence of an irregular movement state such as stick-slip is reduced. As a result, the occurrence of irregular wear on the surface of the charging member, the generation of abnormal noise, and the like are suppressed. When the release agent is a liquid, it also acts as a leveling agent when forming the surface layer. Specifically, metal oxides such as molybdenum disulfide, tungsten disulfide, boron nitride, and lead monoxide can be used. In addition, oil- or solid-state (release resin or powder thereof, a part of the polymer into which a part having release property is introduced) silicon or fluorine-containing compound, wax, higher fatty acid, salt thereof , Esters and other derivatives can also be used.

  The surface layer of the present invention preferably has a thickness of 0.1 μm or more and 100 μm or less. More preferably, they are 1 micrometer or more and 50 micrometers or less. The surface layer 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 or the like on the surface.

  The surface layer can be formed by a coating method such as electrostatic spray coating or dipping coating. Or it can form by adhere | attaching or coat | covering the sheet-shaped or tube-shaped layer beforehand formed into a film thickness with the predetermined | prescribed film thickness. Alternatively, a method of curing and molding the material into a predetermined shape in the mold can also be used. Among these, it is preferable to apply a paint by a coating method to form a coating film. When a layer is formed by a coating method, the solvent used in the coating solution may be any solvent that can dissolve the binder resin. Specific examples are given below. Alcohol (methanol, ethanol, isopropanol etc.), ketone (acetone, methyl ethyl ketone, cyclohexanone etc.), amide (N, N-dimethylformamide, N, N-dimethylacetamide etc.), dimethyl sulfoxide, tetrahydrofuran. These solvents are appropriately selected according to the binder resin used.

  As a method for dispersing the binder, particles and the like in the coating solution, known solution dispersing means such as a ball mill, a sand mill, a paint shaker, a dyno mill, and a pearl mill can be used.

In the present invention, the volume resistivity of the surface layer is preferably 1 × 10 ³ Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less in a 23 ° C./50% RH environment. By setting it within this range, even when a pinhole occurs in the photoreceptor, it is possible to suppress an excessive current from flowing through the pinhole and a drop in the applied voltage.
The charging roller of the present invention usually has an electric resistance of 1 × 10 ⁴ Ω · cm or more and 1 × 10 ⁸ Ω · cm in a 23 ° C./50% RH environment in order to improve the charging of the photoreceptor. The following is preferable.

  FIG. 3 shows a method for measuring the electrical resistance of the charging roller. Both ends of the conductive support 1 are brought into contact with a cylindrical metal 32 having the same curvature as that of the photosensitive member by a bearing 33 under load so as to be parallel to each other. In this state, the cylindrical metal 32 is rotated by a motor (not shown), and the charging roller 6 abutted thereby is driven to rotate. Then, a DC voltage of −200 V is applied from the stabilized power supply 34. The current flowing at this time is measured by an ammeter 35, and the resistance of the charging roller is calculated. Here, the load is 4.9 N, the metal cylinder has a diameter of 30 mm, and the rotation of the metal cylinder has a peripheral speed of 45 mm / sec.

  The charging roller of the present invention may have a so-called crown shape in which the central portion in the longitudinal direction is the thickest and narrows toward both ends in the longitudinal direction from the viewpoint of making the longitudinal nip width uniform with respect to the photoreceptor. it can.

[Electrophotographic equipment]
FIG. 4 is a schematic configuration diagram of an electrophotographic apparatus according to the present invention. A charging device 6 that charges the photosensitive member 5, a latent image forming device 12 that performs exposure, a developing device 7 that develops the toner image, a transfer device 9 that transfers the toner onto the transfer material 8, and a cleaning device 11 that collects the transfer toner on the photosensitive member. And a fixing device 10 for fixing the toner image. The photoreceptor 5 is a rotary drum type having a photosensitive layer on a conductive substrate. The photoreceptor is driven to rotate in the direction of the arrow at a predetermined peripheral speed (process speed). The charging device 6 includes a contact-type charging roller that is placed in contact with the photosensitive member by being pressed with a predetermined force. The charging roller rotates in accordance with the rotation of the photosensitive member, and charges the photosensitive member to a predetermined potential by applying a predetermined DC voltage from a charging power source. For example, an exposure apparatus such as a laser beam scanner is used as the latent image forming apparatus 12 that forms an electrostatic latent image on the photosensitive member. An electrostatic latent image is formed by performing exposure corresponding to image information on a uniformly charged photoconductor. The developing device 7 has a contact-type developing roller disposed close to or in contact with the photoreceptor. The toner electrostatically processed to the same polarity as the photosensitive member charge polarity is developed by reversal development to visualize and develop the electrostatic latent image into a toner image. The transfer device 9 has a contact type transfer roller. The toner image is transferred from the photoreceptor to a transfer material 8 such as plain paper. The transfer material 8 is conveyed by a paper feeding system having a conveying member. The cleaning device 11 has a blade-type cleaning member and a collection container, and after transferring, mechanically scrapes off and collects the transfer residual toner remaining on the photosensitive member. Here, it is also possible to remove the cleaning device by adopting a development simultaneous cleaning system in which the transfer device collects the transfer residual toner. The fixing device 10 is composed of a heated roll or the like, fixes the transferred toner image, and discharges the toner image to the outside of the apparatus. A process cartridge shown in FIG. 5 in which the photosensitive member 5, the charging device 6, the developing device 7, the cleaning device 11, and the like are integrated and configured to be detachable from the main body of the electrophotographic apparatus can also be used.

Hereinafter, the present invention will be described in more detail with reference to specific examples.
<Production Example 1 (Production of Spherical Graphite Particle 1)>
The phenol resin particles having an average particle size of 6.0 μm were subjected to air classification to obtain particles having a sharp distribution having an average particle size of 6.0 μm. The obtained particles were heat-stabilized at 300 ° C. for 1 hour in an oxidizing atmosphere, and then fired at 2200 ° C. in an inert gas atmosphere. The fired particles were further subjected to air classification treatment to obtain spherical graphite particles 1. The average particle size was 5.5 μm. The ratio of the circularity of 0.9 or more was 99.3%.
<Production Example 2 (Production of Spherical Graphite Particles 2)>
Spherical graphite particles 2 were obtained in the same manner as in Production Example 1 except that phenol resin particles having an average particle diameter of 11.0 μm (after air classification) were used in Production Example 1.
<Production Example 3 (Production of Spherical Graphite Particle 3)>
Spherical graphite particles 3 were obtained in the same manner as in Production Example 1 except that phenol resin particles having an average particle size of 21.0 μm (after air classification) were used in Production Example 1.
<Production Example 4 (Production of Spherical Graphite Particles 4)>
100 parts by mass of phenol resin particles having an average particle diameter of 6.0 μm and 10 parts by mass of phenol resin particles having an average particle diameter of 6.0 μm (pulverized product) are mixed with 100 parts by mass, and heated at 300 ° C. for 1 hour in an oxidizing atmosphere. After stabilization treatment, firing was performed at 2200 ° C. in an inert gas atmosphere. The fired particles were further subjected to air classification treatment to obtain spherical graphite particles 4. <Production Example 5 (production of spherical graphite particles 5)>
Using 100 parts by weight of phenol resin particles with an average particle diameter of 10.8 μm (after air classification), using a raikai machine (automatic mortar manufactured by Ishikawa Factory), 13 parts by weight of a coal-based bulk mesophase pitch with an average particle diameter of 3 μm or less Was coated. Then, after heat-stabilizing treatment at 300 ° C. in an oxidizing atmosphere, it was calcined and graphitized at 2200 ° C. in an inert gas atmosphere, and further subjected to air classification to obtain spherical graphite particles 5.
<Production Example 6 (Production of Spherical Graphite Particle 6)>
Β-resin was extracted from coal tar pitch by solvent fractionation and subjected to heavy treatment by hydrogenation. Subsequently, the solvent-soluble component was removed with toluene to obtain a bulk mesophase pitch. After this bulk mesophase pitch was mechanically pulverized, the temperature was increased to 270 ° C. in air at a temperature increase rate of 300 ° C./h, and oxidation treatment was performed. At the time of pulverization, the average particle size was adjusted to about 5 μm. Subsequently, the temperature was increased to 3000 ° C. at a temperature increase rate of 1500 ° C./h under a nitrogen atmosphere, and heat treatment was performed at 3000 ° C. for 15 minutes. Further classification treatment was performed to obtain spherical graphite particles 6.
<Production Example 7 (Production of Spherical Graphite Particles 7)>
In Production Example 6, spherical graphite particles 7 were obtained in the same manner as in Production Example 6, except that the average particle size was adjusted to about 10 μm during pulverization.
<Production Example 8 (Production of Spherical Graphite Particles 8)>
Spherical graphite having an average particle diameter of 10.0 μm was circulated in the apparatus for 90 minutes at a pressure of 300 kPa using a counter jet mill (manufactured by Hosokawa Micron) to obtain spherical graphite particles 8.
<Production Example 9 (Production of Spherical Graphite Particles 9)>
Spheroidal natural graphite having an average particle diameter of 10.0 μm was circulated in the apparatus at a pressure of 300 kPa for 30 minutes using a counter jet mill (manufactured by Hosokawa Micron) to obtain spherical graphite particles 9.
The physical properties of the spherical graphite particles 1 to 9 are shown in Table 1 below.

<Production Example 10 (Production of Composite Conductive Fine Particles)>
To 7.0 kg of silica particles (average particle diameter 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 ) Was mixed and stirred for 30 minutes. The stirring speed at this time was 22 rpm. Into this, 7.0 kg of carbon black particles (particle diameter 20 nm, volume resistivity 1.0 × 10 ² Ω · cm, pH 6.0) was added over 10 minutes while operating the edge runner, and further 588 N / The mixture was stirred for 60 minutes with a linear load of cm (60 kg / cm). In this way, carbon black was adhered to the surface of the methylhydrogenpolysiloxane-coated silica particles. Thereafter, drying was performed at 80 ° C. for 60 minutes using a dryer to obtain composite conductive fine particles. The stirring speed at this time was 22 rpm. The obtained composite conductive fine particles had an average particle diameter of 60 nm and a volume resistivity of 1.1 × 10 ² Ω · cm.
<Production Example 11 (Production 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. This slurry was mixed with a stirrer for 30 minutes, and then supplied to Viscomill in which 80% of the effective internal volume was filled with glass beads having an average particle diameter of 0.8 mm, and wet crushing was performed at a temperature of 35 ± 5 ° C. Toluene was removed from the resulting slurry by distillation under reduced pressure (bath temperature: 110 ° C., product temperature: 30-60 ° C., degree of vacuum: about 100 Torr) using a kneader, and the surface treatment agent was baked at 120 ° C. for 2 hours. Went. The baked particles were cooled to room temperature and then pulverized using a pin mill to obtain surface-treated titanium oxide particles.

Example 1
[Production of Charging Roller 1]
(Preparation of coating solution 1 for adhesive layer)
Methyl ethyl ketone was added to the resol-type phenol resin (specific gravity 1.2), and the solution was adjusted so that the phenol resin content was 9% by mass. 44.4 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (25% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenol resin). . 200 g of the above mixed solution was placed in a glass bottle having an inner 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 10 minutes using a paint shaker disperser.

(Application of coating solution for adhesive layer)
An iron support shaft having a diameter of 6 mm and a length of 252 mm subjected to electroless nickel plating with a thickness of 3 to 6 μm is preheated to 80 ° C. with a hot plate. On the outer circumference of the preheated support shaft, the adhesive layer coating solution 1 was applied to a central portion of 226 mm of the support shaft using a roll coater. After air drying at room temperature for 10 minutes, it was baked in an electric oven set at 200 ° C. for 10 minutes. The thickness of the adhesive layer was 4 μm. The particle diameter of the spherical graphite particles was 5 μm. The ratio of the spherical graphite particles having a circularity of 0.9 or more was 98.1%. Table 2 shows the thickness of the adhesive layer and the physical properties of the conductive material.

(Production of elastic layer)
Epichlorohydrin rubber (EO-EP-AGC ternary copolymer, EO / EP / AGE = 73 mol% / 23 mol% / 4 mol%) with 100 parts by mass, the following components were added, and a closed mixer adjusted to 80 ° C. The raw material compound was prepared by kneading for 15 minutes.
Calcium carbonate 65 parts by weight aliphatic polyester plasticizer 8 parts by weight zinc stearate 1 part by weight 2-mercaptobenzimidazole 0.5 parts by weight zinc oxide 4 parts by weight quaternary ammonium salt 2 parts by weight carbon black (average particle size: 230 nm , Volume resistivity: 0.1 Ω · cm) 5 parts by mass In addition to this, 1.5 parts by mass of sulfur as a vulcanizing agent, 1 part by mass of dibenzothiazyl sulfide (DM) as a vulcanization accelerator, tetramethylthiuram monosulfide ( TS) 1 part by mass was added and kneaded for 10 minutes in a two-roll mill cooled to 25 ° C. to obtain a compound for an elastic layer.

  Along with the conductive support laminated with the adhesive layer, the elastic layer compound was extruded by an extrusion molding machine with a crosshead, and molded into a roller shape having an outer diameter of about 9 mm. Then, it baked at 160 degreeC with the electric oven for 1 hour. Cut off both ends of the rubber to make the rubber length 228 mm, then polish the surface so that it has a roller shape with an outer diameter of 8.5 mm, and form an elastic layer on the conductive support. A roller having was obtained. The crown amount of this roller (the difference between the outer diameter at the center and the outer diameter at a position 90 mm away from the center) was 115 μm.

(Preparation of surface layer)
Methyl isobutyl ketone was added to the caprolactone-modified acrylic polyol solution, and the solution was adjusted so that the solid content was 16% by mass.

  The following components were added to 714.3 parts by mass of this solution (100 parts by mass of acrylic polyol solid content) to prepare a mixed solution of urethane resin.

Composite conductive fine particles (produced in Production Example 10) 45 parts by mass Surface-treated titanium oxide particles (produced in Production Example 11) 20 parts by mass Modified dimethyl silicone oil (* 1) 0.08 parts by mass Blocked isocyanate mixture (* 2) 80 .14 parts by mass At this time, the blocked isocyanate mixture was such that the amount of isocyanate was “NCO / OH = 1.0”.
(* 1) Modified dimethyl silicone oil “SH28PA” (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.)
(* 2) 7: 3 mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) each butanone oxime block body 200 g of the above mixed solution in a glass bottle with an inner volume of 450 mL, glass having an average particle diameter of 0.8 mm as a medium It was put together with 200 g of beads and dispersed for 48 hours using a paint shaker disperser. After dispersion, “MX1000” is equivalent to 10 parts by mass with respect to 100 parts by mass of an acrylic polyol solid content to which 2.24 g of polymethyl methacrylate resin particles “MX1000” (manufactured by Soken Chemical Co., Ltd.) having an average particle diameter of 10 μm is added. Amount). Thereafter, dispersion was performed for 1 hour, and the glass beads were removed to obtain a coating solution for the surface layer. Using the surface layer coating solution, dipping coating was performed once on the elastic roller. After the coating, it was air-dried at room temperature for 30 minutes or more, and dried with a hot air circulating dryer at 80 ° C. for 1 hour and further at 160 ° C. for 1 hour to obtain a charging roller 1 having a surface layer formed on the elastic layer. Here, the dipping coating is as follows. The immersion time was 9 seconds, the dipping coating lifting speed was an initial speed of 20 mm / s and a final speed of 2 mm / s, and the speed was changed linearly with respect to the time.
[Measurement of resistance of charging roller]
The resistance of the prepared charging roller was measured.

The measurement method of electrical resistance is shown. As shown in FIG. 3A, the shaft 1 at both ends of the charging roller is brought into contact with the cylindrical metal 32 having the same curvature as the photosensitive member by the bearings 33a and 33b to which the load is applied so that the charging roller is parallel. Let Next, as shown in FIG. 3B, the cylindrical metal 32 is rotated by a motor (not shown), and the roller is driven and rotated while being in contact with the cylindrical metal. In this state, the resistance of the charging roller was calculated by measuring the current flowing through the charging roller with an ammeter 35 when a DC voltage of −200 V was applied from the stabilized power supply 34. In the present invention, a force of 5 N is applied to both ends of the shaft to contact a metal cylinder having a diameter of 30 mm, and the metal cylinder is rotated at a peripheral speed of 45 mm / sec. In addition, when the charging roller of Example 1 was left in an N / N (normal temperature and normal humidity: 23 ° C./55% RH) environment for 24 hours or more, the electrical resistance was measured to be 2.0 × 10 ⁵ Ω. . The results of electrical resistance are shown in Table 2.
[Image evaluation]
The charging roller 1 produced above was left in a 40 ° C., 95% RH environment for one month, then removed from the environment and left in a 23 ° C., 50% RH environment for 24 hours. Thereafter, the taken-out charging roller 1 was incorporated into an electrophotographic apparatus, and image evaluation was performed in a low temperature and low humidity environment (15 ° C., 10% RH). As an electrophotographic apparatus having the configuration shown in FIG. 4, a Canon color laser jet printer (LBP5400) was used with a recording medium output speed of 200 mm / sec (A4 vertical output). The resolution of the image is 600 dpi, and the primary charging output is a DC voltage of −1100V.
The process cartridge for the printer was used as a process cartridge having the configuration shown in FIG. 5 (for black). The output image was visually evaluated based on the following criteria.
Rank A: A white haze-like image is not generated.
Rank B: A slight white haze-like image is generated in a part of the image.
Rank C: A white haze-like image is conspicuous in the image.
Rank D: Many white haze-like images are conspicuous in the image.
[Durable image evaluation]
As an electrophotographic apparatus having the configuration shown in FIG. 4, a Canon color laser jet printer (LBP5400) was used with a recording medium output speed of 200 mm / sec (A4 vertical output). The resolution of the image is 600 dpi, and the primary charging output is a DC voltage of −1100V.
The process cartridge for the printer was used as a process cartridge having the configuration shown in FIG. 5 (for black). The charging roller 1 produced as described above was mounted on a process cartridge. This process cartridge was mounted on the electrophotographic apparatus. Evaluation was performed as follows. The primary charging was evaluated using the above charging roller 1 in a low temperature and low humidity environment (15 ° C., 10% RH). Specifically, an endurance test for printing a plurality of images with a printing density of 4% (an image in which a horizontal line with a width of 2 dots and an interval of 50 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive member) at a process speed of 200 mm / sec. went. Then, a halftone image (an image in which a horizontal line having a width of 1 dot and an interval of 2 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive member) is output for image checking after 10,000 images have been output. About the obtained image, the streak-like image was observed visually and evaluated on the following reference | standard.
Rank A: A streak-like image was not generated.
Rank B: Minor streaks occur in some areas.
Rank C: Minor streaks are generated on the entire surface.
Rank D: Lines are clearly visible <Example 2>
In Example 1, the charging roller was the same as Example 1 except that the addition amount of the spherical graphite particles in the adhesive coating solution was 71.8 parts by mass (equivalent to 35% by volume with respect to the adhesive layer). 2 was produced. The charging roller 2 was evaluated in the same manner as in Example 1.
<Example 3>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. To this solution 909.0 parts by mass (100 parts by mass of resole phenol resin), 44.4 parts by mass of spherical graphite particles 2 (produced in Production Example 2) (corresponding to 25% by volume with respect to the adhesive layer) was added. A charging roller 3 was produced in the same manner as in Example 1 except that. The charging roller 3 was evaluated in the same manner as in Example 1.
<Example 4>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 61.1 parts by mass of spherical graphite particles 4 (produced in Production Example 4) (corresponding to 25% by volume with respect to the adhesive layer) were added to 909.0 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 4 was produced in the same manner as in Example 1 except that. The charging roller 4 was evaluated in the same manner as in Example 1.
<Example 5>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 14% by mass. 71.8 parts by mass of spherical graphite particles 3 (produced in Production Example 3) (corresponding to 35% by volume with respect to the adhesive layer) was added to 614.3 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 5 was produced in the same manner as in Example 1 except that. The charging roller 5 was evaluated in the same manner as in Example 1.
<Example 6>
In Example 1, except that 44.4 parts by mass of spherical graphite particles 2 (produced in Production Example 2) (corresponding to 25% by volume with respect to the adhesive layer) was added, charging roller 6 was the same as Example 1. Was made. The charging roller 6 was evaluated in the same manner as in Example 1.
<Example 7>
In Example 1, the charging roller 7 was the same as Example 1 except that 44.4 parts by mass of spherical graphite particles 3 (produced in Production Example 3) (corresponding to 25% by volume with respect to the adhesive layer) was added. Was made. The charging roller 7 was evaluated in the same manner as in Example 1.
<Example 8>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 14% by mass. 14.8 parts by mass of spherical graphite particles 3 (produced in Production Example 3) (corresponding to 10% by volume with respect to the adhesive layer) is added to 714.3 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 8 was produced in the same manner as in Example 1 except that. The charging roller 8 was evaluated in the same manner as in Example 1.
<Example 9>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 7% by mass. 14.8 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 10% by volume with respect to the adhesive layer) is added to 1428.5 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 9 was produced in the same manner as in Example 1 except that. The charging roller 9 was evaluated in the same manner as in Example 1.
<Example 10>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 7% by mass. 44.4 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 25% by volume with respect to the adhesive layer) are added to 1428.5 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 10 was produced in the same manner as in Example 1 except that. The charging roller 10 was evaluated in the same manner as in Example 1.
<Example 11>
In Example 10, the charging roller 11 was produced in the same manner as in Example 10 except that the elastic layer was formed using the following elastic layer compound. The charging roller 11 was evaluated in the same manner as in Example 1.

(Preparation of compound for elastic layer)
Epichlorohydrin rubber (EO-EP-AGC terpolymer, EO / EP / AGE = 56 mol% / 40 mol% / 4 mol%) To 100 parts by mass, the following components were added, and the mixture was adjusted to 80 ° C. The raw material compound was prepared by kneading for 15 minutes.
Calcium carbonate 65 parts by weight aliphatic polyester plasticizer 8 parts by weight zinc stearate 1 part by weight 2-mercaptobenzimidazole 0.5 parts by weight zinc oxide 4 parts by weight quaternary ammonium salt 2 parts by weight carbon black (average particle size: 230 nm , Volume resistivity: 0.1 Ω · cm) 5 parts by mass 1.5 parts by mass of sulfur as a vulcanizing agent, 1 part by mass of dibenzothiazyl sulfide (DM) as a vulcanization accelerator, tetramethylthiuram monosulfide ( TS) 1 part by mass was added and kneaded for 10 minutes in a two-roll mill cooled to 25 ° C. to obtain a compound for an elastic layer.
<Example 12>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. To 909.0 parts by mass of this solution (100 parts by mass of resol type phenol resin), 45.8 parts by mass of spherical graphite particles 5 (produced in Production Example 5) (corresponding to 25% by volume with respect to the adhesive layer) were added. A charging roller 12 was produced in the same manner as in Example 1 except that. The charging roller 12 was evaluated in the same manner as in Example 1.
<Example 13>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 10% by mass. 61.1 parts by mass (equivalent to 25% by volume with respect to the adhesive layer) of spherical graphite particles 8 (produced in Production Example 8) was added to 1000.0 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 13 was produced in the same manner as in Example 1 except that. The charging roller 13 was evaluated in the same manner as in Example 1.
<Example 14>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. 14.8 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 10% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 14 was produced in the same manner as in Example 1 except that. The charging roller 14 was evaluated in the same manner as in Example 1.
<Example 15>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. 14.8 parts by mass of spherical graphite particles 4 (produced in Production Example 4) (corresponding to 10% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 15 was produced in the same manner as in Example 1 except that. The charging roller 15 was evaluated in the same manner as in Example 1.
<Example 16>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 61.1 parts by mass of spherical graphite particles 7 (produced in Production Example 7) (corresponding to 25% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 16 was produced in the same manner as in Example 1 except that. The charging roller 16 was evaluated in the same manner as in Example 1.
<Example 17>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 20.4 parts by mass of spherical graphite particles 7 (produced in Production Example 7) (corresponding to 10% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 17 was produced in the same manner as in Example 1 except that. The charging roller 17 was evaluated in the same manner as in Example 1.
<Example 18>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. With respect to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenol resin), 88.9 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 40% by volume with respect to the adhesive layer) were added. A charging roller 18 was produced in the same manner as in Example 1 except that.
<Example 19>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. To 1111.1 parts by mass of this solution (100 parts by mass of resol type phenol resin), 10.0 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (equivalent to 7% by volume with respect to the adhesive layer) were added. A charging roller 19 was produced in the same manner as in Example 1 except that. The charging roller 19 was evaluated in the same manner as in Example 1.
<Example 20>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 14% by mass. 88.9 parts by mass of spherical graphite particles 3 (produced in Production Example 3) (corresponding to 40% by volume with respect to the adhesive layer) were added to 714.3 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 20 was produced in the same manner as in Example 1 except that. The charging roller 20 was evaluated in the same manner as in Example 1.
<Example 21>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 14% by mass. To 714.3 parts by mass of this solution (100 parts by mass of resol type phenol resin), 10.0 parts by mass of spherical graphite particles 3 (produced in Production Example 3) (equivalent to 7% by volume with respect to the adhesive layer) were added. A charging roller 21 was produced in the same manner as in Example 1 except that. The charging roller 21 was evaluated in the same manner as in Example 1.
<Example 22>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 7% by mass. 88.9 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 40% by volume with respect to the adhesive layer) were added to 1428.5 parts by mass of this solution (100 parts by mass of resol type phenol resin). A charging roller 22 was produced in the same manner as in Example 1 except that. The charging roller 22 was evaluated in the same manner as in Example 1.
<Example 23>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 7% by mass. To 1428.5 parts by mass of this solution (100 parts by mass of resol type phenolic resin), 10.0 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (equivalent to 7% by volume with respect to the adhesive layer) was added. A charging roller 23 was produced in the same manner as in Example 1 except that. The charging roller 23 was evaluated in the same manner as in Example 1.
<Example 24>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. To this solution 1111.1 parts by mass (100 parts by mass of resole phenolic resin), 18.1 parts by mass of spherical graphite particles 6 (produced in Production Example 6) (equivalent to 9% by volume with respect to the adhesive layer) were added. A charging roller 24 was produced in the same manner as in Example 1 except that. The charging roller 24 was evaluated in the same manner as in Example 1.
<Example 25>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 9% by mass. 12111 parts by mass of spherical graphite particles 6 (produced in Production Example 6) (corresponding to 40% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 25 was produced in the same manner as in Example 1 except that. The charging roller 25 was evaluated in the same manner as in Example 1.
<Example 26>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. To this solution 1111.1 parts by mass (100 parts by mass of resole phenolic resin), 18.1 parts by mass of spherical graphite particles 7 (produced in Production Example 7) (equivalent to 9% by volume with respect to the adhesive layer) were added. A charging roller 26 was produced in the same manner as in Example 1 except that. The charging roller 26 was evaluated in the same manner as in Example 1.
<Example 27>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 12111 parts by mass of spherical graphite particles 7 (produced in Production Example 7) (corresponding to 40% by volume with respect to the adhesive layer) were added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 27 was produced in the same manner as in Example 1 except that. The charging roller 27 was evaluated in the same manner as in Example 1.
<Example 28>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 10% by mass. To 1000.0 parts by mass of this solution (100 parts by mass of resol type phenol resin), 18.1 parts by mass of spherical graphite particles 9 (produced in Production Example 9) (corresponding to 9% by volume with respect to the adhesive layer) were added. A charging roller 28 was produced in the same manner as in Example 1 except that. The charging roller 28 was evaluated in the same manner as in Example 1.
<Example 29>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 10% by mass. To 1000.0 parts by mass of this solution (100 parts by mass of resol type phenol resin), 122.2 parts by mass of spherical graphite particles 9 (produced in Production Example 9) (corresponding to 40% by volume with respect to the adhesive layer) was added. A charging roller 29 was produced in the same manner as in Example 1 except that. The charging roller 29 was evaluated in the same manner as in Example 1.
<Comparative Example 1>
In Example 1, methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 8% by mass. Except that 37.5 parts by mass of carbon black (corresponding to 20% by volume with respect to the adhesive layer) was added to 1250.0 parts by mass of this solution (100 parts by mass of resol type phenolic resin), the same procedure as in Example 1 was performed. A charging roller 30 was produced. The charging roller 30 was evaluated in the same manner as in Example 1.
<Comparative Example 2>
Methyl ethyl ketone was added to the polycondensed carboxylic acid polyester resin (hot melt adhesive, specific gravity 1.1) to adjust the resin content to 8% by mass. The same as Example 1 except that 40.9 parts by mass of carbon black (corresponding to 20% by volume with respect to the adhesive layer) was added to 1250.0 parts by mass of this solution (100 parts by mass of the polycondensed carboxylic polyester resin). Thus, a charging roller 31 was produced. The charging roller 31 was evaluated in the same manner as in Example 1.
<Comparative Example 3>
Methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. A charging roller 32 was produced in the same manner as in Example 1 except that no conductive material was added. The charging roller 32 was evaluated in the same manner as in Example 1.
<Comparative example 4>
Methyl ethyl ketone was added to the polycondensed carboxylic acid polyester resin (hot melt adhesive) to adjust the resin content to 11% by mass. 48.5 parts by mass of spherical graphite particles 2 (produced in Production Example 2) (corresponding to 25% by volume with respect to the adhesive layer) with respect to 1111.1 parts by mass of this solution (100 parts by mass of polycondensed carboxylic polyester resin) A charging roller 33 was produced in the same manner as in Example 1 except that the above was added. The charging roller 33 was evaluated in the same manner as in Example 1.
<Comparative Example 5>
Methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 61.1 parts by mass of natural graphite (average particle size 10 μm) (corresponding to 25% by volume with respect to the adhesive layer) was added to 1111.1 parts by mass of this solution (100 parts by mass of polycondensed carboxylic polyester resin). A charging roller 34 was produced in the same manner as in Example 1 except for the above. The charging roller 34 was evaluated in the same manner as in Example 1.
<Comparative Example 6>
Methyl ethyl ketone was added to the resol type phenol resin to adjust the phenol resin content to 11% by mass. 44.4 parts by mass of spherical graphite particles 1 (produced in Production Example 1) (corresponding to 25% by volume with respect to the adhesive layer) were added to 1111.1 parts by mass of this solution (100 parts by mass of resol type phenolic resin). A charging roller 35 was produced in the same manner as in Example 1 except that. The charging roller 35 was evaluated in the same manner as in Example 1.

  As shown in the results of Table 2 above, the charging roller of the present invention suppresses the generation of white haze-like images and the occurrence of streak-like images, and can provide good images. Electrophotographic apparatus and process cartridge It is preferable to be incorporated in

1 conductive support shaft 2 adhesive layer 3 elastic layer 4 surface layer

Claims (3)

A conductive support shaft whose surface is made of metal;
An adhesive layer containing a phenolic resin formed on the peripheral surface of the conductive support shaft;
In a charging roller having an elastic layer containing epichlorohydrin rubber formed on the peripheral surface of the adhesive layer,
A charging roller, wherein graphite particles having a particle size larger than the thickness of the adhesive layer are disposed between the conductive support shaft and the elastic layer.   An electrophotographic apparatus comprising the charging roller according to claim 1.   A process cartridge comprising the charging roller according to claim 1 and detachably attached to a main body of an electrophotographic apparatus.

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