JP5409209B2 - Electrophotographic equipment - Google Patents

Description

  The present invention relates to an electrophotographic apparatus having an electrophotographic photoreceptor, contact charging means, exposure means, contact developing means, and transfer means.

In recent years, an electrophotographic apparatus employing a contact charging method in which a voltage is applied to a charging member (contact charging member) arranged in contact with the electrophotographic photosensitive member to charge the electrophotographic photosensitive member has become widespread. In particular, a charging roller that is a roller-shaped charging member is used. The charging roller is brought into contact with the surface of the electrophotographic photosensitive member, and a voltage obtained by superimposing an alternating current voltage on the direct current voltage is applied thereto to charge the electrophotographic photosensitive member. The mainstream is a method for performing charging (AC / DC contact charging method) or a method for charging an electrophotographic photosensitive member by applying a voltage of only a direct current voltage (DC contact charging method).
The AC / DC contact charging method requires a direct current power supply and an alternating current power supply as compared with the case of the DC contact charging method, so that the electrophotographic apparatus is increased in cost and the size of the electrophotographic apparatus is increased. In addition, there is a problem that durability of the charging roller and the electrophotographic photosensitive member is reduced by consuming a large amount of alternating current.
Therefore, it can be said that the DC contact charging method is more preferable in view of cost reduction, miniaturization, and high durability of the electrophotographic apparatus.

  However, the electrophotographic apparatus adopting the DC contact charging method is inferior in the uniformity of the surface potential of the electrophotographic photosensitive member (charging uniformity) at the time of charging as compared with the electrophotographic apparatus adopting the AC / DC contact charging method. There is a tendency. Therefore, a non-uniform image having a stripe shape in the longitudinal direction (direction perpendicular to the circumferential direction) of the electrophotographic photosensitive member due to uneven charging in a halftone image (hereinafter also referred to as “charging horizontal stripe”) tends to be a problem.

  As described in Patent Document 1, a roller-shaped contact charging member is generally used. For example, in this case, a conductive elastic layer and a resistance control layer are sequentially formed around a conductive cored bar. In many cases, the surface layer has a laminated structure. Depending on the resistance value required for the elastic layer, for example, a resistance added with a conductivity imparting material such as a solid electrolyte such as carbon black, carbon fiber, metal oxide, metal powder, perchlorate, or a surfactant is added. There is a way to control.

Examples of the material for the resistance control layer include resins and rubbers such as polyamide, polyurethane, fluorine, polyvinyl alcohol, silicon, NBR, EPDM, CR, IR, BR, and hydrin rubber. There is a mixture of fillers and additives. It has been proposed to use the material as described above and to set the electric resistance value of the charging member to 1 × 10 ³ to 1 × 10 ¹⁰ Ω.

In Patent Document 2, fine particle conductive materials such as carbon black, tin oxide, and titanium oxide are usually used for resistance control of the charging member. For carbon black, the powder resistance is 10 ⁻² Ωcm and the particle diameter is about 0.02 μm. For tin oxide and titanium oxide, the powder resistance is 10 ¹ to 10 ² Ωcm and the particle diameter is about 0.2 μm. However, the volume resistivity of the charging member itself is not specified.

Patent Document 3 describes that the volume resistance value of the charging member is preferably in the range of 10 ⁰ to 10 ¹² Ωcm, particularly 10 ² to 10 ¹⁰ Ωcm, and a very wide range is defined. In the embodiment, since a composite voltage of an AC voltage and a DC voltage is applied, a problem specific to charging roller charging in which only a DC component voltage is applied is not described.

In these Patent Documents 1 to 3, there is no description regarding the charging horizontal stripe when the charging member described is used. In particular, there is no description of charging horizontal stripes and white spots as problems in charging roller charging in which only a DC component voltage is applied, and the dielectric loss tan δ of the electrophotographic photosensitive member is not described and is unknown. Is also not clear.
It has been considered that the dielectric loss tan δ of the electrophotographic photosensitive member is usually preferably low in order to charge the electrophotographic photosensitive member and maintain the dark portion potential. Patent Document 4 describes a characteristic diagnosis method for measuring the volume resistance value R of an electrophotographic photosensitive member and / or the loss coefficient D of the electrophotographic photosensitive member to determine the degree of deterioration of the electrophotographic photosensitive member. There is a description that the loss factor D of the photoconductor is 0.009 to 0.015 when measured at 100 kHz and 5 VAC.

  Patent Document 5 describes that the tan δ of the substance used for the protective layer is low although it is not the dielectric loss tan δ of the electrophotographic photosensitive member. Patent Document 6 states that ε = 3.4 or less and Tanδ = 0.001 to 0.03 of the charge transport layer when measured at a frequency of 20 Hz, but not the dielectric loss tanδ of the electrophotographic photosensitive member, are good. .

  However, also in Patent Documents 4 to 6, the influence of the dielectric loss tan δ of the electrophotographic photosensitive member on the charging lateral stripe and the relationship with the volume resistivity of the charging roller are unknown. In particular, there is no description regarding charging lateral streaks in a charging roller having a high volume resistivity.

In Patent Document 7, there is a description that when the oxide layer coated with oxygen-deficient tin oxide is contained in the electroconductive layer of the electrophotographic photoreceptor, the charging lateral streak is improved, but the electrophotographic photoreceptor is subjected to severe conditions. It is unclear about the charged horizontal streaks after storage at. There is no description of dielectric loss tan δ of the electrophotographic photosensitive member. Since there is no description about the case where the volume resistivity of the charging roller is high (10 ¹⁰ Ωcm to ^{10 12} Ωcm), the relationship between the dielectric loss tan δ of the electrophotographic photosensitive member and the charging lateral stripe, and the volume resistivity of the charging roller The relationship between charged horizontal streaks after severe storage is unknown.

  In Patent Document 8, there is a description that the intermediate layer of the electrophotographic photosensitive member contains barium sulfate particles coated with tin oxide, but the dielectric loss tan δ of the electrophotographic photosensitive member is not described and is unknown. Further, the charging means is not specified, and it is not possible to derive a problem specific to charging roller charging in which a voltage of only a direct current component is applied.

Patent Document 9 discloses a charging means for charging an electrophotographic photosensitive member by applying a bias of only a DC component, and developing the toner by transferring the toner to an electrostatic latent image on the electrophotographic photosensitive member by applying a developing bias. In an electrophotographic apparatus having developing means using a non-contact jumping development system, the electrophotographic photosensitive member is an electrophotographic photosensitive member in which a conductive layer, an intermediate layer, and a photosensitive layer are provided in this order on a support, The layer contains a binder resin and conductive particles, and the conductive particles are TiO ₂ particles coated with oxygen-deficient SnO ₂ , and the volume resistivity of the conductive layer is 1 × 10 ⁷ Ω · cm or more 1 × Although described electrophotographic apparatus, characterized in that at most 10 ¹¹ Ω · cm, the effect is a particular problem at the electrophotographic apparatus having a developing unit using a non-contact jumping developing system developing An effect on charging unevenness of the electrophotographic photosensitive member by application of bias, not the effect on the problem at a charging lateral stripe generated in and contact development system a DC contact charging system. The dielectric loss tan δ of the electrophotographic photosensitive member is not described and is unknown.

Japanese Patent Laid-Open No. 08-160709 Japanese Patent Laid-Open No. 08-137194 Japanese Patent Registration No. 2588873 Japanese Patent Laid-Open No. 04-178649 Japanese Patent Laid-Open No. 05-232735 JP 2003-131406 A JP 2007-047736 A Japanese Patent Registration No. 3118129 JP 2007-017876 A

  When charging with a contact charging means that charges the electrophotographic photosensitive member by applying only a DC voltage to the charging roller that is brought into contact with the electrophotographic photosensitive member with a nip, a voltage obtained by superimposing the AC voltage on the DC voltage is applied. Thus, the surface potential uniformity (charging uniformity) of the electrophotographic photosensitive member during charging tends to be inferior compared to the case where the electrophotographic photosensitive member is charged by a charging means for charging. Therefore, a non-uniform image having a stripe shape in the longitudinal direction (direction perpendicular to the circumferential direction) of the electrophotographic photosensitive member due to uneven charging in a halftone image (hereinafter also referred to as “charging horizontal stripe”) tends to be a problem. Further, in an electrophotographic apparatus having a developing means using a contact developing system, the problem of the charged lateral stripe is more serious because it becomes more prominent.

  An object of the present invention is a charging unit in which a charging unit applies only a DC voltage to a charging roller that is brought into contact with the electrophotographic photosensitive member with a nip to charge the electrophotographic photosensitive member, and the developing unit is a developer. In an electrophotographic apparatus which is a contact developing means for developing by bringing a developer carrying body carrying a toner into contact with an electrophotographic photosensitive member, image defects due to charged horizontal stripes from the initial stage to the endurance after storage under severe conditions It is an object of the present invention to provide an electrophotographic apparatus that does not generate any problems.

The present invention provides an electrophotographic photosensitive member having a conductive layer, an intermediate layer, and a photosensitive layer in this order on a support, an electrophotographic apparatus having a charging unit, an exposing unit, a developing unit, and a transferring unit.
The charging means is contact charging means for charging the electrophotographic photosensitive member by applying only a DC voltage to a roller-shaped charging member brought into contact with the electrophotographic photosensitive member with a nip, and the roller-like charging member The volume resistivity of the charging member is 10 ¹⁰ Ωcm or more and 10 ¹² Ωcm or less,
The developing means is a contact developing means for performing development by bringing a developer carrying member carrying a developer into contact with the electrophotographic photosensitive member;
The conductive layer of the electrophotographic photoreceptor contains barium sulfate particles coated with oxygen-deficient tin oxide ;
The coverage of the tin oxide is more than 15 mass% 10 mass% or more by weight of the barium sulfate particles,
Dielectric loss tanδ of the electrophotographic photosensitive member in the frequency fHz obtained from the following equation (1) is 0.0 5 0 0 or more. The electrophotographic apparatus is characterized in that it is 300 or less.
f = P / X (1)
(In formula (1), X represents the nip width (mm) between the roller-shaped charging member and the electrophotographic photosensitive member, and P represents the process speed (mm / sec) of the electrophotographic apparatus. )

  According to the present invention, the charging unit is a contact charging unit that charges the electrophotographic photosensitive member by applying only a DC voltage to a charging roller that is brought into contact with the electrophotographic photosensitive member with a nip, and the developing unit is a developing unit. In the electrophotographic apparatus which is a contact developing means for developing by bringing the developer carrying body carrying the developer into contact with the electrophotographic photosensitive member, from the initial stage to the endurance even after being stored under severe conditions An electrophotographic apparatus in which no image defect occurs can be provided.

1 shows an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. 1 shows an example of a schematic configuration of an intermediate transfer type color electrophotographic apparatus having the electrophotographic photosensitive member of the present invention. 1 shows an example of a schematic configuration of an in-line color electrophotographic apparatus having the electrophotographic photosensitive member of the present invention. An example of schematic structure of the charging roller of this invention is shown. An example of schematic structure of the charging device containing the charging roller of this invention is shown. An example of the measuring apparatus schematic of the volume resistivity of the charging roller of this invention is shown.

First, the structure of the electrophotographic photoreceptor used in the electrophotographic apparatus of the present invention will be described.
The electrophotographic photosensitive member used in the electrophotographic apparatus of the present invention is an electrophotographic photosensitive member in which a conductive layer, an intermediate layer, and a photosensitive layer are provided in this order on a support.

  The support may be anything that has conductivity (conductive support), and is provided with a metal support such as aluminum or stainless steel, or a layer that imparts conductivity on metal, paper, or plastic. Support. Examples of the shape of the support include a cylindrical shape and a belt shape.

  Even if the photosensitive layer is a single layer type in which the charge transport material and the charge generation material are contained in the same layer, the layer is separated into a charge generation layer containing the charge generation material and a charge transport layer containing the charge transport material. A mold (function separation type) may be used, but a laminated type is preferable from the viewpoint of electrophotographic characteristics. The laminated photosensitive layer has a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, and a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. However, the normal layer type is preferable from the viewpoint of electrophotographic characteristics.

In the present invention, a conductive layer is provided on the support for the purpose of covering scratches on the support and for the purpose of suppressing interference fringes due to scattering when the exposure light is laser light. In addition, an interference fringe can be suppressed also by processing the surface of a support body by a cutting process, an alumite process, a dry blast process, a wet blast process. The conductive layer contains particles obtained by coating a conductive metal oxide with nonconductive inorganic particles. The conductive layer can be formed by dispersing the particles in a binder resin. Here, the conductive metal oxide refers to a metal oxide having a volume resistivity of 10 ² Ωcm or less. For example, metal oxides such as tin oxide doped with antimony oxide, indium oxide doped with tin oxide, or metal oxides doped with metal oxides, or oxygen deficient metal oxidation in which oxygen in the metal oxides is lost by a reduction method And oxygen deficient tin oxide. The doping amount of antimony oxide or tin oxide to be doped is preferably 0.01 to 30% by weight, more preferably 0.1 to 10% by weight, based on the conductive metal oxide.

Non-conductive inorganic particles refer to inorganic particles having a volume resistivity of 10 ⁵ to 10 ¹⁰ Ωcm. Examples include titanium oxide, barium sulfate, and zirconium oxide. As the non-conductive inorganic particles, barium sulfate that exhibits the most effect on charged horizontal stripes is preferable.

In the present invention, the volume resistivity of the conductive metal oxide and the non-conductive inorganic particles was measured using a resistance measuring device Loresta AP (Loresta Ap) manufactured by Mitsubishi Yuka. The powder to be measured was hardened at a pressure of 500 kg / cm ² and attached to the measuring device as a coin sample.

  The coverage of the conductive metal oxide of the particles obtained by coating the conductive metal oxide with the nonconductive inorganic particles means the mass ratio of the conductive metal oxide covering the nonconductive inorganic particles. It is expressed as mass% of the conductive metal oxide with respect to the mass of the particles. In the present invention, the coverage necessary for setting the dielectric loss tan δ of the electrophotographic photosensitive member to 0.020 or more and 0.500 or less is 10% by mass or more and less than 25% by mass, preferably 10% by mass or more and 20% by mass. %.

In the present invention, the average particle diameter of the particles is a value measured by a centrifugal sedimentation method.
Examples of the binder material for the conductive layer include resins (binder resins) such as phenol resin, polyurethane, polyamide, polyimide, polyamideimide, polyvinyl acetal, epoxy resin, acrylic resin, melamine resin, and polyester. These can be used alone or in combination of two or more. Also, among various resins, suppression of migration (melting) to other layers, adhesion to the support, dispersibility / dispersion stability of particles formed by coating conductive metal oxide with nonconductive inorganic particles, From the viewpoint of solvent resistance after film formation, the binder resin of the conductive layer is preferably a curable resin, and more preferably a thermosetting resin. Specifically, a thermosetting phenol resin or polyurethane is preferable. When a curable resin is used as the binder resin for the conductive layer, the binder material contained in the conductive layer coating solution is a monomer and / or oligomer of the curable resin.

  As a dispersion method, for example, particles obtained by coating the conductive metal oxide with nonconductive inorganic particles together with a binder resin and a solvent, a homogenizer, an ultrasonic wave, a ball mill, a vibration ball mill, a sand mill, an attritor, or The method of disperse | distributing using a roll mill is mentioned. Particles obtained by coating conductive metal oxide with non-conductive inorganic particles are preferably dispersed with a high share in order to control the dielectric loss tan δ of the electrophotographic photosensitive member. preferable. Moreover, the one where the rotation speed of a sand mill is higher is preferable, and 900 rpm or more is preferable.

  From the viewpoint of concealing surface defects of the support, such as sacrificial convex defects, the thickness of the conductive layer is preferably 5 to 40 μm, more preferably 10 to 30 μm.

In the present invention, an intermediate layer having an adhesion function and a barrier function is provided on the conductive layer. The intermediate layer is formed by dissolving a resin such as polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, or polyether urethane in an appropriate solvent, applying the solution onto the conductive layer, and drying the solution. be able to.
The thickness of the intermediate layer is preferably 0.05 to 5 μm, and more preferably 0.3 to 1 μm.

When the photosensitive layer is a normal layer type photosensitive layer, a charge generation layer is provided on the intermediate layer.
Examples of the charge generating substance include selenium-tellurium, pyrylium, thiapyrylium dye, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, azo (trisazo, disazo, monoazo), indigo, quinacridone, and asymmetric quinocyanine.

  Examples of the binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, Examples include polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, and epoxy resin.

  The charge generation layer comprises a charge generation substance, 0.3 to 4 times (mass ratio) of a binder resin and a solvent, a homogenizer, an ultrasonic disperser, a ball mill, a vibration ball mill, a sand mill, an attritor, a roll mill, or It can be formed by applying a coating solution for charge generation layer obtained by thoroughly dispersing using a liquid collision type high-speed disperser and drying it. Note that the binder resin may be added after the charge generating material is dispersed, or the binder resin may not be used if the charge generating material has a film-forming property. The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 to 2 μm.

  When the photosensitive layer is a normal type photosensitive layer, a charge transport layer is provided on the charge generation layer. Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent and drying it. When the charge transport layer is a surface layer of an electrophotographic photosensitive member, a charge transport layer coating solution obtained by dissolving the diorganopolysiloxane with a solvent in addition to the charge transport material and the binder resin, It can be formed by coating and drying. The mass ratio between the charge transport material and the binder resin is preferably 5: 1 to 1: 5, and more preferably 3: 1 to 1: 3. The thickness of the charge transport layer is preferably 5 to 50 μm, and more preferably 10 to 30 μm.

  Examples of the binder resin for the charge transport layer include thermoplastic resins and curable resins. Specifically, phenoxy resin, polyacrylamide resin, polyvinyl butyral resin, polyarylate resin, polysulfone resin, polyamide resin, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester Resins, alkyd resins, polycarbonate resins, polyurethane resins, or copolymers containing two or more repeating units of these resins, such as styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers. It is done. It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

  A charge generation material, a charge transport material, etc., which are organic photoconductive materials, are generally sensitive to ultraviolet rays, ozone, oil stains, and metals, so a protective layer is provided on the photosensitive layer for the purpose of protecting the photosensitive layer, This may be used as the surface layer of the electrophotographic photosensitive member.

The protective layer serving as the surface layer of the electrophotographic photosensitive member can be formed by applying and drying a protective layer coating solution obtained by dissolving various binder resins in a solvent. As the binder resin used for the protective layer, for example, phenol resin, acrylic resin, polystyrene resin, polyester resin, polycarbonate resin, polyarylate resin, polysulfone resin, polyphenylene oxide resin, epoxy resin, polyurethane resin, alkyd resin, siloxane resin, An unsaturated resin is mentioned. In particular, phenol resin, acrylic resin, epoxy resin, polyurethane resin, and siloxane resin are preferable.
In addition, when using a resin obtained from a condensation monomer or a radical polymerization monomer having an unsaturated group as a binder resin for the protective layer, after applying a coating solution, irradiate energy light such as heat or ultraviolet rays. It may be cured to form a protective layer.
The thickness of the protective layer is preferably 0.5 to 7 μm, particularly preferably 0.5 to 5.5 μm.

  If necessary, the surface layer of the electrophotographic photoreceptor of the present invention may further contain conductive particles such as metals and conductive metal oxides and charge transport materials.

  Of the above layers, the layer serving as the surface layer of the electrophotographic photosensitive member may contain fluorine atom-containing resin particles. Examples of the fluorine atom-containing resin include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin and ethylene difluoride dichloride resin, and these Fluorine-based graft polymer obtained by copolymerizing a copolymer or a macromonomer composed of an oligomer having a polymerizable functional group at one end of each molecular chain and having a molecular weight of 1,000 to 10,000 and a fluorine-based polymerizable monomer It is done.

  For the surface layer of the electrophotographic photosensitive member, an acrylic ester or methacrylic ester having a side chain grafted with a silicone unit and a vinyl polymerizable monomer such as an acrylic ester, methacrylic ester or styrene are used together. It is preferable to contain a resin obtained by polymerization.

  The layer that becomes the surface layer of the electrophotographic photosensitive member may contain an antioxidant. Antioxidants include, for example, antioxidants for plastics, rubber, petroleum, and fats, and hindered amine compounds and hindered phenol compounds are particularly preferable.

  When applying the coating liquid for each of the above layers, for example, an application method such as dip coating (dip coating), spray coating, spinner coating, roller coating, Meyer bar coating, or blade coating is used. be able to.

The method for measuring tan δ according to the present invention will be described below.
First, in order to measure the dielectric loss (tan δ) of the electrophotographic photosensitive member, an electrophotographic photosensitive member 1 was prepared in the same manner as described above on a support member in which an aluminum sheet having a thickness of about 50 μm was separately wound. . Thereafter, the aluminum sheet on which the conductive layer, the intermediate layer, and the photosensitive layer were sequentially applied was peeled off, and the aluminum sheet was cut into an appropriate size, which was used as a sample for measuring dielectric loss (tan δ). On this measurement sample, gold (electrode) having an area of 5.31 × 10 ⁻⁴ m ² and a thickness of 600 ± 100 nm was vapor-deposited with a sputtering apparatus (trade name: SC-708AT QUICK COATER) manufactured by SANYU DENSHI. . Then, it was left to stand under normal temperature and normal humidity (temperature 23 ° C./humidity 50% RH) for 24 hours, and dielectric loss (tan δ) was measured.

Dielectric loss (tan δ) is determined by applying an impedance analyzer (trade name: frequency response analyzer 1260 type, dielectric constant interface 1296 type) manufactured by Solartron in an environment of normal temperature and normal humidity (temperature 23 ° C./humidity 50% RH). The measurement was performed under conditions of 100 mV and a frequency fHz obtained from the following formula (1).
f = P / X (1)
In the above formula (1), X represents the nip width (mm) between the charging roller and the electrophotographic photosensitive member, and P represents the process speed (mm / sec) of the electrophotographic apparatus.

  In the present invention, tan δ means a charging delay. In contact charging of only a direct current component using a charging roller (roller-shaped charging member), charging is performed using discharge at a discharge gap portion before and after the contact portion (nip) between the charging roller and the electrophotographic photosensitive member. . The side before passing through the nip with respect to the rotation direction of the electrophotographic photosensitive member is called upstream, and the side after passing through the nip is called downstream. Since the charging property upstream and downstream of the charging roller has an influence, the time for passing through the nip width of the charging roller is a large factor. For this reason, the tan δ (charge delay) at the frequency determined from the nip width of the charging roller and the speed passing through the nip width of the charging roller, that is, the process speed of the electrophotographic apparatus, has an influence, and is related to the charging horizontal stripe. The inventors have found.

  In the present invention, the dielectric loss tan δ of the electrophotographic photosensitive member at a frequency fHz obtained from the above formula (1) is 0.020 or more and 0.500 or less. When it is 0.020 or less, the effect of the present invention does not appear, and when it is 0.500 or more, the effect of the present invention is poor and the charging property is deteriorated. Preferably they are 0.035 or more and 0.300 or less, More preferably, they are 0.050 or more and 0.100 or less.

The charging means of the present invention will be described in detail.
The charging means of the present invention is a contact charging method in which a voltage is applied to a charging member (contact charging member) disposed in contact with the electrophotographic photosensitive member to charge the electrophotographic photosensitive member. Specifically, this is a system (DC contact charging system) in which the charging roller is brought into contact with the surface of the electrophotographic photosensitive member, and a voltage of only a direct current voltage is applied thereto to charge the electrophotographic photosensitive member. The structure as the charging member used is shown below.

FIG. 4 is a schematic diagram of the configuration of the charging roller of the present invention, and FIG. 5 is a schematic view of a portion of an image forming apparatus including a charging unit using the charging roller of the present invention and a member to be charged.
The charging roller 201 has a medium resistance surface layer (charging layer) 201-1 for controlling the resistance of the charging roller, and an elasticity necessary for forming a uniform nip with the surface of the electrophotographic photosensitive member as a charged body. The conductive elastic layer 201-2 has a conductive support 201-3 that is a support member (core metal) (FIG. 4). The conductive elastic layer 201-2 is formed by dispersing a conductive material such as carbon black in a solid rubber such as EPDM, acrylic rubber, or urethane rubber. The surface layer 201-1 is a medium resistance layer, and is formed by dispersing a conductive substance such as carbon black in a resin such as nylon or urethane. The resistance value of the charging member is preferably selected as appropriate in accordance with the environment in which it is used, charging efficiency, or the electric withstand voltage characteristics of the electrophotographic photosensitive member.

  The distance between the center of the electrophotographic photosensitive member to be charged and the charging roller 201 is the conductive elastic layer 201 in order to stably control the contact area width (= nip) of the charging roller 201 in the rotation direction of the electrophotographic photosensitive member. -2 hardness adjustment and strength adjustment of the spring 201-4 that press-contacts the charging roller 201 against the electrophotographic photosensitive member 202 are preferably performed. In addition, a suitable distance may be set using a roller (not shown), a spacer (not shown), or the like. In addition, a mechanism for adjusting the nip may be provided. As a mechanism for adjusting the nip, there is a method of controlling the distance between the charging member and the surface of the electrophotographic photosensitive member which is a member to be charged.

The volume resistivity of the charging roller is 10 ¹⁰ Ωcm or more and 10 ¹² Ωcm or less. When the volume resistivity of the charging roller is less than 10 ¹⁰ Ω, the effect of the present invention is not remarkable. On the other hand, when the volume resistivity of the charging roller is 10 ¹² Ωcm or more, the effect of the present invention is diminished and the charging property is lowered.

A method for measuring the volume resistivity of the charging roller in the present invention will be described below.
The volume resistivity of the charging roller was measured by a method as shown in FIG. In FIG. 6, 2 is a charging roller, 15 is a cylindrical electrode made of stainless steel, 16 is a resistor, and 17 is a recorder. The pressing force between them was the same as in the electrophotographic apparatus used, and the cylindrical electrode and the charging roller to be measured were made to be the same as the nip width between the electrophotographic photosensitive member and the charging roller in the electrophotographic apparatus. In such a contact state, the cylindrical electrode is rotated at the same speed (process speed) as the operation in the electrophotographic apparatus, and the charging roller is rotated at the same speed as the rotation. The volume resistivity when -200 V was applied to the cylindrical electrode was measured as the volume resistivity of the charging roller.

FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.
In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 2 in a direction indicated by an arrow at a predetermined peripheral speed.

  The peripheral surface (surface) of the electrophotographic photosensitive member 1 that is rotationally driven is applied with a high voltage of only a direct current component by a charging unit (primary charging unit) 3 having a roller-shaped charger described later, and is positive or negative. It is uniformly charged to a predetermined potential. Next, exposure light (image exposure light) 4 output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed with toner of the developing unit 5 to become a toner image. As the developing means 5, a contact developing means is used as will be described later. Next, the toner image formed and supported on the peripheral surface of the electrophotographic photosensitive member 1 is transferred from the transfer material supply unit (not shown) by the transfer bias from the transfer unit (transfer roller) 6 to the electrophotographic photosensitive member 1 and the transfer unit. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material P that has received the transfer of the toner image is separated from the peripheral surface of the electrophotographic photosensitive member 1 and is introduced into the fixing means 8 to undergo image fixing, and is printed out of the apparatus as an image formed product (print, copy). Out.

  The peripheral surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by the cleaning means (cleaning blade) 7 to remove the transfer residual toner, and is repeatedly used for image formation. In some cases, after the cleaning means, a charge removal process is performed by pre-exposure light (not shown) from a pre-exposure means (not shown).

  Among the above-described components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6 and the cleaning unit 7, a plurality of components are housed in a container and integrally combined to form a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 1, the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5 and the cleaning unit 7 are integrally supported, and can be attached to and detached from the electrophotographic apparatus main body using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is configured.

  Maintaining high releasability on the surface of the electrophotographic photosensitive member for a long period of time, making the transfer efficiency sufficiently high without increasing the transfer current, and obtaining a sharp electrostatic latent image for all electrophotographic devices Although it is required, since the color electrophotographic apparatus (multiple transfer system, intermediate transfer system, inline system, etc.) is required to be achieved at a higher level, the electrophotographic photosensitive member of the present invention is It is particularly suitable as an electrophotographic photoreceptor for a color electrophotographic apparatus.

  Hereinafter, a color electrophotographic apparatus will be described by taking an intermediate transfer type color electrophotographic apparatus and an inline type color electrophotographic apparatus as examples. In the following description, four colors (yellow, magenta, cyan, and black) are given as examples. However, the “color” in the present invention is not limited to four colors, and is multicolor, that is, two types. That is the color.

FIG. 2 shows an example of a schematic configuration of an intermediate transfer type color electrophotographic apparatus having the electrophotographic photosensitive member of the present invention.
In FIG. 2, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is driven to rotate about a shaft 2 in a direction indicated by an arrow at a predetermined peripheral speed.

  The peripheral surface (surface) of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by the charging unit 3, and then exposure unit (not shown) such as slit exposure or laser beam scanning exposure. ) From the exposure light (image exposure light) 4 output. The exposure light at this time is exposure light corresponding to the first color component image (for example, yellow component image) of the target color image. In this way, a first color component electrostatic latent image (yellow component electrostatic latent image) corresponding to the first color component image of the target color image is sequentially formed on the peripheral surface of the electrophotographic photoreceptor 1.

  The intermediate transfer member (intermediate transfer belt) 11 stretched by the stretching roller 12 and the secondary transfer counter roller 13 has substantially the same peripheral speed as the electrophotographic photosensitive member 1 in the direction of the arrow (for example, the peripheral speed of the electrophotographic photosensitive member 1). 97 to 103%).

  The first color electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed by the first color toner (yellow toner) of the first color component developing means (yellow component developing means) 5Y to be the first color. It becomes a toner image (yellow toner image). Next, the first color toner image formed and supported on the peripheral surface of the electrophotographic photosensitive member 1 is transferred to the electrophotographic photosensitive member 1 and the primary transfer unit (primary transfer roller) 6p by the primary transfer bias from the primary transfer unit 6p. Are sequentially transferred onto the peripheral surface of the intermediate transfer body 11 passing between the two.

  The peripheral surface of the electrophotographic photosensitive member 1 after the transfer of the first color toner image is cleaned by the cleaning means 7 after removal of the primary transfer residual toner, and then used for image formation of the next color.

  Similarly to the first color toner image, the second color toner image (magenta toner image), the third color toner image (cyan toner image), and the fourth color toner image (black toner image) are also surrounded by the circumference of the electrophotographic photoreceptor 1. Formed on the surface and sequentially transferred onto the peripheral surface of the intermediate transfer member 11. In this way, a synthetic toner image corresponding to the target color image is formed on the peripheral surface of the intermediate transfer body 11. During primary transfer of the first to fourth colors, the secondary transfer unit (secondary transfer roller) 6s and the charge applying unit (charge applying roller) 7r are separated from the peripheral surface of the intermediate transfer body 11.

  The composite toner image formed on the peripheral surface of the intermediate transfer member 11 is transferred from the transfer material supply unit (not shown) to the secondary transfer counter roller 13 (the intermediate transfer member 11 is moved by the secondary transfer bias from the secondary transfer unit 6s. And the secondary transfer means 6s (contact portion) are sequentially transferred to the transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the intermediate transfer body 11 in order. .

  The transfer material P that has received the transfer of the synthetic toner image is separated from the peripheral surface of the intermediate transfer body 11 and is introduced into the fixing means 8 to receive image fixing, whereby a color image formed product (print, copy) is taken out of the apparatus. Printed out.

  Charge applying means 7r is brought into contact with the peripheral surface of the intermediate transfer body 11 after the synthetic toner image is transferred. The charge applying unit 7r applies a charge having a polarity opposite to that at the time of primary transfer to the secondary transfer residual toner on the peripheral surface of the intermediate transfer body 11. The secondary transfer residual toner to which a charge having a polarity opposite to that at the time of primary transfer is applied to the peripheral surface of the electrophotographic photoreceptor 1 at and near the contact portion between the electrophotographic photoreceptor 1 and the intermediate transfer body 11. Is transcribed. In this way, the peripheral surface of the intermediate transfer body 11 after the synthetic toner image is transferred is cleaned by receiving the transfer residual toner. The secondary transfer residual toner transferred to the peripheral surface of the electrophotographic photosensitive member 1 is removed by the cleaning unit 7 together with the primary transfer residual toner on the peripheral surface of the electrophotographic photosensitive member 1. The transfer of the secondary transfer residual toner from the intermediate transfer member 11 to the electrophotographic photosensitive member 1 can be performed simultaneously with the primary transfer, so that the throughput is not reduced.

  In addition, the peripheral surface of the electrophotographic photosensitive member 1 after the transfer residual toner is removed by the cleaning unit 7 may be subjected to a static elimination process with the pre-exposure light from the pre-exposure unit. However, as shown in FIG. In the case of contact charging means using a charging roller or the like, pre-exposure is not necessarily required.

FIG. 3 shows an example of a schematic configuration of an in-line color electrophotographic apparatus having the electrophotographic photosensitive member of the present invention.
In FIG. 3, 1Y, 1M, 1C, and 1K are drum-shaped electrophotographic photosensitive members (first to fourth color electrophotographic photosensitive members) of the present invention, each centered on axes 2Y, 2M, 2C, and 2K. And is rotated at a predetermined peripheral speed in the direction of the arrow.

  The circumferential surface (surface) of the first color electrophotographic photosensitive member 1Y that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a first color charging unit (first color primary charging unit) 3Y. Next, exposure light (image exposure light) 4Y output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. The exposure light 4Y is exposure light corresponding to a first color component image (for example, a yellow component image) of a target color image. Thus, the first color component electrostatic latent image (yellow component electrostatic latent image) corresponding to the first color component image of the target color image is sequentially formed on the peripheral surface of the first color electrophotographic photoreceptor 1Y. .

  The transfer material conveyance member (transfer material conveyance belt) 14 stretched by the tension roller 12 has substantially the same peripheral speed as the first to fourth color electrophotographic photoreceptors 1Y, 1M, 1C, 1K in the direction of the arrow ( For example, it is rotationally driven at 97 to 103% of the peripheral speeds of the first to fourth color electrophotographic photoreceptors 1Y, 1M, 1C, and 1K. Further, the transfer material (paper or the like) P fed from the transfer material supply means (not shown) is electrostatically carried (adsorbed) on the transfer material conveying member 14 and is electrophotographic for the first to fourth colors. The photoreceptors 1Y, 1M, 1C, and 1K are sequentially transported between the transfer material transport members (contact portions).

  The first-color component electrostatic latent image formed on the peripheral surface of the first-color electrophotographic photosensitive member 1Y is developed with the toner of the first-color developing means 5Y to form a first-color toner image (yellow toner image). Become. Next, the first color toner image formed and supported on the peripheral surface of the first color electrophotographic photoreceptor 1Y is transferred to the first color by the transfer bias from the first color transfer means (first color transfer roller) 6Y. Transfer is sequentially performed on the transfer material P carried on the transfer material transport member 14 that passes between the color electrophotographic photoreceptor 1Y and the first color transfer means 6Y.

  The peripheral surface of the first color electrophotographic photoreceptor 1Y after the transfer of the first color toner image is cleaned by receiving the transfer residual toner by the first color cleaning means (first color cleaning blade) 7Y. After that, the first color toner image is repeatedly used.

  The first color charging unit 3Y, the first color exposure unit 4Y, the first color developing unit 5Y, and the first color transfer unit 6Y are collectively referred to as a first color image forming unit.

  Second color charging unit 3M, second color exposure unit 4M, second color developing unit 5M, second color image forming unit having second color transfer unit 6M, third color charging unit 3C, Third color image forming unit having three color exposure means 4C, third color development means 5C, third color transfer means 6C, fourth color charging means 3K, fourth color exposure means 4K, fourth color The operation of the fourth color image forming unit having the color developing unit 5K and the fourth color transfer unit 6K is the same as that of the first color image forming unit, and is carried by the transfer material conveying member 14 and A second color toner image (magenta toner image), a third color toner image (cyan toner image), and a fourth color toner image (black toner image) are sequentially transferred onto the transfer material P onto which the one color toner image has been transferred. Go. In this way, a synthetic toner image corresponding to the target color image is formed on the transfer material P carried on the transfer material conveying member 14.

  The transfer material P on which the synthetic toner image is formed is separated from the peripheral surface of the transfer material conveying member 14 and is introduced into the fixing unit 8 to be subjected to image fixing, whereby the image is fixed to the outside as a color image formed product (print, copy). Printed out.

  Further, the peripheral surfaces of the first to fourth color electrophotographic photoreceptors 1Y, 1M, 1C, and 1K after the transfer residual toner is removed by the first to fourth color cleaning units 7Y, 7M, 7C, and 7K, Although neutralization may be performed by pre-exposure light from the pre-exposure means, pre-exposure is not always necessary.

Next, the intermediate transfer member will be described.
Examples of the intermediate transfer member include an endless intermediate transfer belt stretched by a stretch roller (including a drive roller and a tension roller). The volume resistivity of the intermediate transfer belt is preferably 10 ⁶ to 10 ¹² Ω · cm. If the volume resistivity of the intermediate transfer belt is too low, there will be a large difference in the resistance value of the intermediate transfer belt between the portion that received the primary transfer and the portion that did not, so that the toner for the second and subsequent colors will be transferred efficiently. Cannot be obtained, and an image with the desired hue cannot be obtained. Also, if the resistance value of the intermediate transfer belt is too high, when the toner for the second and subsequent colors is primarily transferred, the toner for which the primary transfer has been completed may return to the electrophotographic photosensitive member.

  Examples of the material for the intermediate transfer belt include resins such as urethane resin, fluorine resin, polycarbonate resin, polyethylene terephthalate, polyamide resin, and polyimide resin, and elastic materials such as silicone rubber, urethane rubber, and hydrin rubber. Resin, polyimide and polyethylene terephthalate are preferable from the viewpoint of strength and electrophotographic characteristics. Resistance adjustment can be performed by dispersing conductive particles such as carbon black and metal particles (titanium oxide particles, tin oxide particles, etc.) in the resin or elastic material. By increasing the amount of conductive particles, the volume resistivity can be lowered.

  Regarding the tension of the intermediate transfer belt, it is preferable to set the elongation rate to be within 1% so that the intermediate transfer belt is not broken or permanently deformed. The thickness of the intermediate transfer belt is preferably 10 to 200 μm.

Next, the transfer material conveying member will be described.
Examples of the transfer material transport member include an endless transfer material transport belt stretched by a stretch roller (including a driving roller and a tension roller). The volume resistivity of the transfer material conveying belt is preferably 10 ⁷ to 10 ¹³ Ω · cm, and more preferably 10 ⁸ to 10 ¹² Ω · cm. If the volume resistivity is too large, the charge accumulation during transfer may adversely affect the removal of the toner adhering to the transfer material conveying belt. On the other hand, if the volume resistivity is too small, the adsorption of the transfer material becomes unstable. There is a case.

  In addition, examples of the material for the transfer material transport belt include resins such as urethane resin, fluororesin, polycarbonate resin, polyethylene terephthalate, polyamide resin, and polyimide resin, and elastic materials such as silicone rubber, urethane rubber, and hydrin rubber. Fluorine resins (polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, etc.), polycarbonate resins, polyethylene terephthalate, and polyimide resins are preferable from the viewpoints of transferability and transfer material adsorption. Resistance adjustment can be performed by dispersing conductive particles such as carbon black and metal particles (titanium oxide particles, tin oxide particles, etc.) in the resin or elastic material. By increasing the amount of conductive particles, the volume resistivity can be lowered.

  Regarding the tension of the transfer material conveyance belt, it is preferable to set the elongation rate to be within 1% so that the transfer material conveyance belt is not broken or permanently deformed. Further, the thickness of the transfer material transport belt is preferably 10 to 200 μm.

  In order to prevent the charge accumulation on the transfer material conveying belt from adversely affecting the transfer property and the adsorbing property of the transfer material, a method of discharging the transfer material conveying belt by the charge eliminating means before the toner image transfer of the next color Is mentioned. However, when the toner is attached on the transfer material conveyance belt, passing the portion of the static eliminator may cause contamination of the static eliminator with toner, charge up of the toner (or charge loss), and in some cases, the transfer material conveyance belt. It may cause a discharge breakdown.

  The surface roughness Rz of the peripheral surface of the transfer material conveying belt (the surface on the side carrying the transfer material) is preferably 5 μm or less, and more preferably 3 μm or less. When the surface roughness Rz exceeds 5 μm, the adhesion between the contaminated toner and the transfer material transport belt surface is increased, and it may be difficult to remove the contaminated toner.

  On the other hand, the surface roughness Rz of the transfer material conveying belt is preferably 0.05 μm or more. In order to control the charge amount per unit area of the toner, inorganic particles such as silica particles, titanium oxide particles, and zinc oxide particles having a particle diameter of about 0.001 to 0.05 μm are externally added. Such sub-micron particles have a strong electrostatic attraction force to the transfer material conveyance belt, and are difficult to remove from the transfer material conveyance belt surface. Therefore, it is preferable that the surface roughness Rz of the conveying belt is made larger than the particle diameter (diameter) of these external additives and they are embedded in the conveying belt to some extent.

  In the present invention, the volume resistivity of the intermediate transfer belt and the transfer material conveying belt is a measurement value obtained by applying 100 V with a high resistance meter R8340 manufactured by ADVANTEST, using a measurement probe based on JIS-K6911. The values are normalized by the thicknesses of the intermediate transfer belt and the transfer material conveyance belt.

  In order to make the surface roughness of the peripheral surface of the intermediate transfer belt or the transfer material conveying belt within the above range, for example, a method of heat forming the belt in a mold is used, and the surface of the surface in contact with the belt of the mold at this time Examples thereof include a method of making the roughness sufficiently smaller than the above value, or a method of smoothing the belt surface after molding by post-processing such as polishing.

Next, the toner will be described.
The electrophotographic photosensitive member of the present invention is remarkably effective in improving transfer efficiency when a toner having a smaller particle diameter is used, and more prominent when a non-magnetic toner containing no magnetic material is used.
As the toner, a non-magnetic one-component toner containing a binder resin, a colorant, a charge control agent and a low softening material is preferably used.

  As the binder resin for the toner, those usually used may be used. Examples thereof include styrene copolymers such as styrene-polyester and styrene-butyl acrylate, polyester resins, and epoxy resins.

  The colorant may be a commonly used colorant. Examples of yellow toner include benzine yellow pigment, foron yellow, acetoacetanilide anionyl insoluble azo pigment, monoazo dye, and azomethine dye.

  For magenta toner, xanthene magenta dye phosphotungsten molybdate acid lake pigment, 2,9-dimethylquinacridone, naphthol insoluble azo pigment, anthraquinone dye, colorant comprising xanthene dye and organic carboxylic acid, thioindigo, naphthol insoluble azo pigment Is mentioned.

  For cyan toners, copper phthalocyanine pigments can be mentioned.

  The charge control agent may be a commonly used one. For example, examples of the negative charge control agent include alkyl salicylic acid metal complexes, digalbonic acid metal complexes, and polycyclic salicylic acid metal salts. Examples thereof include quaternary ammonium salts, benzothiazole derivatives, guanamine derivatives, dibutyltin oxide, and other nitrogen-containing compounds.

  Low softening materials include polymethylene waxes such as paraffin wax, polyolefin wax, microcrystalline wax, and Fischer tropish wax, amide waxes, higher fatty acids, long chain alcohols, ester waxes, and their graft compounds and blocks. Examples include derivatives such as compounds, and a content of 5 to 30% by mass with respect to the total mass of the toner is preferable.

  Further, the number average diameter (D1) corresponding to the circle of the toner is preferably 2 to 10 μm. The average circularity of the toner is preferably 0.920 to 0.995, more preferably 0.950 to 0.995, and still more preferably 0.970 to 0.990. The standard deviation of circularity of the toner is preferably less than 0.040, more preferably less than 0.035, and on the other hand, it is preferably 0.015 or more.

  In the present invention, the circle-equivalent number average diameter (D1), the circularity, the average circularity, and the circularity standard deviation are each a number-based circle equivalent diameter-circularity scattergram measured by a flow type particle image measuring device. Are the equivalent number average diameter (D1), circularity, average circularity, and circularity standard deviation.

In the present invention, as described above, the contact developing type means is used as the developing means.
In general, for non-magnetic toner, the toner is coated on the developing sleeve (developer carrier) with a blade, and for magnetic toner, the toner is coated with magnetic force, and the toner is removed by rotating the developing sleeve. The toner is conveyed to an electrophotographic photosensitive member, and toner is applied to the electrophotographic photosensitive member for development.

  There are one-component development in which toner is applied to an electrophotographic photoreceptor and development, and two-component development in which a mixture of toner and magnetic carrier is used as a developer. There is development.

  That is, (1) one-component non-contact development in which toner is applied to an electrophotographic photoreceptor in a non-contact state and developed, and (2) one component to be applied in toner and applied to an electrophotographic photoreceptor in development. Contact development method (3) Using a mixture of a non-magnetic toner and a magnetic carrier as a developer, this developer is carried on a developing sleeve by a magnetic force and conveyed to an electrophotographic photosensitive member. Four types of two-component non-contact development methods in which the electrophotographic photosensitive member is applied and developed in a contact state, and (4) two-component contact development methods in which a developer is applied to the electrophotographic photosensitive member in a contact state and developed. It is divided roughly into.

  Among the above four development methods, the development sleeve (developer carrying member) is brought into contact with the electrophotographic photosensitive member (hereinafter referred to as contact development method), that is, the one-component contact development method and the two-component contact development method. These contact development methods are suitable for image forming methods that require high image quality because these contact development methods are easy to obtain high resolution and good density gradation characteristics.

  In the present invention, a developing means using the above-described one-component contact development method or two-component contact development method is used.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these examples. In the examples, “part” means “part by mass”.

カーボンブラック（表面未処理品）（平均粒径：０．２μｍ、体積抵抗率：０．１Ω・ｃｍ） ５部
以上の材料を温度５０℃に調節した密閉型ミキサーにて１０分間混練し、原料コンパウンドを調製した。このコンパウンドに原料のゴムのエピクロルヒドリンゴム１００部に対し、加硫剤としての硫黄１部、加硫促進剤としてのＤＭ（ジベンゾチアジルスルフィド）１部およびＴＳ（テトラメチルチウラムモノスルフィド）０．５部を加え、２０℃に冷却した二本ロール機にて１０分間混練した。
混練にて得られたコンパウンドを、直径６ｍｍ（φ６ｍｍ）ステンレス製の芯金に外径φ１５ｍｍのローラー状になるように押し出し成型機にて成型し、加熱蒸気加硫した後、外径が１０ｍｍになるように研磨加工を行い、弾性層（導電性弾性層）を有するローラーを得た。この際、研磨加工においては、幅広研磨方式を採用した。ローラー長は２３２ｍｍとした。 (Production example of charging roller)
(Preparation of charging roller 1-1)
First, the elastic layer was produced by the following method.
Epichlorohydrin rubber terpolymer 100 parts (epichlorohydrin: ethylene oxide: allyl glycidyl ether = 40 mol%: 56 mol%: 4 mol%)
Light calcium carbonate 30 parts Aliphatic polyester plasticizer 5 parts Zinc stearate 1 part Anti-aging agent MB (2-mercaptobenzimidazole) 0.5 part Zinc oxide 5 parts Quaternary ammonium salt represented by the following structural formula 2 parts

Carbon black (surface untreated product) (average particle size: 0.2 μm, volume resistivity: 0.1 Ω · cm) 5 parts The above materials are kneaded for 10 minutes in a closed mixer adjusted to a temperature of 50 ° C. A compound was prepared. For this compound, 100 parts of epichlorohydrin rubber as a raw material, 1 part of sulfur as a vulcanizing agent, 1 part of DM (dibenzothiazyl sulfide) as a vulcanization accelerator and 0.5 part of TS (tetramethylthiuram monosulfide) The mixture was added and kneaded for 10 minutes in a two-roll mill cooled to 20 ° C.
The compound obtained by kneading was molded on a 6 mm (φ6 mm) stainless steel core in an extruding machine so as to form a roller with an outer diameter of φ15 mm, heated and steam vulcanized, and then the outer diameter became 10 mm. Polishing was performed to obtain a roller having an elastic layer (conductive elastic layer). At this time, a wide polishing method was employed in the polishing process. The roller length was 232 mm.

A surface layer was formed on the elastic layer. The surface layer was formed by dip coating the following surface layer coating solution. The number of dip coatings was two.
First, as a material for the surface layer coating solution,
Caprolactone-modified acrylic polyol solution 100 parts Methyl isobutyl ketone 250 parts Conductive tin oxide particles (treated with trifluoropropyltrimethoxysilane) (average particle size: 0.05 μm, volume resistivity: 10 ³ Ω · cm) 130 parts Hydrophobic silica (treated with dimethylpolysiloxane) (average particle size: 0.02 μm, volume resistivity: 10 ¹⁶ Ω · cm) 3 parts Modified dimethyl silicone oil 0.08 parts Crosslinked polymethyl methacrylate (PMMA) particles (average Particle size: 4.98 μm) Using 80 parts, a mixed solution was prepared using a glass bottle as a container. This was filled with glass beads (average particle size 0.8 mm) as a dispersion medium so that the filling rate was 80%, and dispersed for 18 hours using a paint shaker disperser. A mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) butanone oxime block 1: 1 (mass ratio) was added to the obtained dispersion solution.
NCO / OH = 1.0
Then, a surface layer coating solution for dip coating was prepared.
The surface layer coating solution was dip coated twice on the surface of the elastic layer, allowed to air dry, and then dried at a temperature of 160 ° C. for 1 hour to prepare a charging roller (roller-shaped charging member) 1-1.
The particle size distribution of the particles added to the surface layer coating solution was measured using a laser diffraction particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation. The measurable particle size range is 0.015 to 500 μm.

(Preparation of charging roller 1-2)
A charging roller 1-2 was prepared in the same manner as the charging roller 1-1 except that the amount of the conductive tin oxide particles added to the surface layer coating solution was 155 parts.

(Preparation of charging roller 1-3)
A charging roller 1-3 was prepared in the same manner as the charging roller 1-1 except that the amount of the conductive tin oxide particles added to the surface layer coating solution was 75 parts.

(Preparation of charging roller 1-4)
A charging roller 1-4 was prepared in the same manner as the charging roller 1-1 except that the amount of conductive tin oxide particles added to the surface layer coating solution was 180 parts.

(Preparation of charging roller 1-5)
A charging roller 1-5 was prepared in the same manner as the charging roller 1-1 except that the amount of the conductive tin oxide particles added to the surface layer coating solution was 55 parts.

(Example of production of electrophotographic photoreceptor)
<Example of preparation of coating solution for conductive layer>
(Preparation of coating liquid A for conductive layer)
55 parts of oxygen deficient SnO ₂ coated barium sulfate particles (SnO ₂ coverage (mass ratio) is 15%), phenol resin as binder resin (trade name: Priorofen J-325, Dainippon Ink & Chemicals, Inc. ), Resin solid content 60%) 36.5 parts, 35 parts of methoxypropanol as a solvent are dispersed in a sand mill using glass beads with a diameter of 0.5 mm at a disc rotation speed of 1200 rpm for 3.5 hours to obtain a dispersion. Was prepared.
In this dispersion, 3.9 parts of silicone resin particles (trade name: Tospearl 120, manufactured by GE Toshiba Silicone Co., Ltd., average particle size 2 μm) as a surface roughness imparting agent, silicone oil as a leveling agent (trade name: 0.001 part of SH28PA (Toray Dow Corning Silicone Co., Ltd.) was added and stirred to prepare a coating liquid A for conductive layer.
The average particle diameter of the oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.35 μm.

(Preparation of coating liquid B for conductive layer)
A conductive layer coating solution B was prepared in the same manner as the conductive layer coating solution A except that the SnO ₂ coverage (mass ratio) was changed to 10%.
The average particle diameter of the oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.35 μm.

(Preparation of coating liquid C for conductive layer)
A conductive layer coating solution C was prepared in the same manner as the conductive layer coating solution A except that the SnO ₂ coverage (mass ratio) was changed to 25%.
The average particle diameter of the oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.35 μm.

(Preparation of coating liquid D for conductive layer)
Oxygen-deficient SnO ₂ coated barium sulfate particles (SnO ₂ coverage (mass ratio) 15%) were changed to indium doped SnO ₂ coated TiO ₂ particles (SnO ₂ coverage (mass ratio) 15%). Except for the above, a conductive layer coating solution D was prepared in the same manner as the conductive layer coating solution A.
The average particle diameter of the tin oxide-doped indium oxide-coated TiO ₂ particles in this conductive layer coating solution was 0.35 μm.

(Preparation of coating liquid E for conductive layer)
A conductive layer coating solution E was prepared in the same manner as the conductive layer coating solution D except that the SnO ₂ coverage (mass ratio) was changed to 10%.
The average particle diameter of the tin oxide-doped indium oxide-coated TiO ₂ particles in this conductive layer coating solution was 0.35 μm.

(Preparation of coating liquid F for conductive layer)
The oxygen-deficient SnO ₂ -coated barium sulfate particles (SnO ₂ coverage (mass ratio) is 15%) were changed to oxygen-deficient SnO ₂ -coated TiO ₂ particles (SnO ₂ coverage (mass ratio) was 15%). A conductive layer coating solution F was prepared in the same manner as the conductive layer coating solution A except for the above.
The average particle diameter of the oxygen-deficient SnO ₂ -coated TiO ₂ particles in this conductive layer coating solution was 0.20 μm.

(Preparation of coating liquid G for conductive layer)
The oxygen-deficient SnO ₂ -coated barium sulfate particles (SnO ₂ coverage (mass ratio) is 15%) were changed to fluorine-doped SnO ₂ -coated calcium oxide particles (SnO ₂ coverage (mass ratio) was 15%). Except for the above, a conductive layer coating solution G was prepared in the same manner as the conductive layer coating solution A.
The average particle diameter of the fluorine-doped SnO ₂ -coated calcium oxide particles in this conductive layer coating solution was 0.20 μm.

(Preparation of coating liquid H for conductive layer)
Oxygen-deficient SnO ₂ coated barium sulfate particles (SnO ₂ coverage (mass ratio) 15%) were changed to tantalum doped SnO ₂ coated zirconium oxide particles (SnO ₂ coverage (mass ratio) 15%). Except for the above, a conductive layer coating solution H was prepared in the same manner as the conductive layer coating solution A.
The average particle diameter of the tantalum-doped SnO ₂ -coated zirconium oxide particles in this conductive layer coating solution was 0.20 μm.

(Preparation of coating liquid I for conductive layer)
A conductive layer coating solution I was prepared in the same manner as the conductive layer coating solution C, except that the sand mill disk rotation speed was changed to 1000 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid J for conductive layer)
A conductive layer coating solution J was prepared in the same manner as the conductive layer coating solution C, except that the sand mill disk rotation speed was changed to 900 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid K for conductive layer)
A conductive layer coating solution K was prepared in the same manner as the conductive layer coating solution C, except that the sand mill disc rotation speed was changed to 800 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid L for conductive layer)
A conductive layer coating solution L was prepared in the same manner as the conductive layer coating solution A except that the sand mill disk rotation speed was changed to 1000 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid M for conductive layer)
A conductive layer coating solution M was prepared in the same manner as the conductive layer coating solution B except that the number of revolutions of the sand mill disk was changed to 1100 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid N for conductive layer)
A conductive layer coating solution N was prepared in the same manner as the conductive layer coating solution A except that the number of revolutions of the sand mill disk was changed to 1000 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid O for conductive layer)
A conductive layer coating solution O was prepared in the same manner as the conductive layer coating solution A except that the disc rotation speed of the sand mill was changed to 900 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid P for conductive layer)
A conductive layer coating solution P was prepared in the same manner as the conductive layer coating solution A except that the disc rotation speed of the sand mill was changed to 800 rpm.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid Q for conductive layer)
A conductive layer coating solution Q was prepared in the same manner as the conductive layer coating solution A except that the SnO ₂ coverage (mass ratio) was changed to 5%.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

(Preparation of coating liquid R for conductive layer)
A conductive layer coating solution R was prepared in the same manner as the conductive layer coating solution A except that the SnO ₂ coverage (mass ratio) was changed to 30%.
The average particle size of oxygen-deficient SnO ₂ -coated barium sulfate particles in this conductive layer coating solution was 0.57 μm.

<Example of production of electrophotographic photosensitive member>
(Preparation of electrophotographic photoreceptor 2-1)
An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 257 mm and a diameter of 24 mm manufactured by a manufacturing method including an extrusion process and a drawing process was used as a support.
The conductive layer coating liquid A is dip-coated on a support in a temperature 23 ° C./humidity 60% RH environment, dried and thermally cured at 140 ° C. for 30 minutes, thereby forming a conductive layer having a thickness of 30 μm. Formed.
Next, 4.5 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Teikoku Chemical Industry Co., Ltd.) and 1.5 parts of copolymer nylon resin (Amilan CM8000, manufactured by Toray Industries, Inc.) The intermediate layer coating solution obtained by dissolving in a mixed solvent of methanol 65 parts / n-butanol 30 parts is dip-coated on the conductive layer and dried at a temperature of 100 ° C. for 10 minutes, whereby the film thickness is reduced. A 0.6 μm intermediate layer was formed.
Next, the Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction are 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 °, and 28.3 °. Sand mill apparatus using 10 parts of glass beads having a diameter of 1 mm, 10 parts of crystalline hydroxygallium phthalocyanine having a strong peak, 5 parts of polyvinyl butyral (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 250 parts of cyclohexanone And then, 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution.
This charge generation layer coating solution was dip-coated on the intermediate layer and dried at a temperature of 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.16 μm.

ポリカーボネート樹脂（商品名：Ｚ４００、三菱エンジニアリングプラスチックス（株）製）１０部を、ジメトキシメタン３０部／クロロベンゼン７０部の混合溶媒に溶解させて、電荷輸送層用塗布液を調製した。
この電荷輸送層用塗布液を、電荷発生層上に浸漬塗布し、これを３０分間温度１２０℃で乾燥させることによって、膜厚が１８μｍの電荷輸送層を形成した。
このようにして、電荷輸送層が表面層である電子写真感光体２−１を作製した。
また、別途、このアルミニウムシリンダー上に５０μｍのアルミニウム箔を巻きつけて固定し、その上に上記と同様に導電層、中間層、電荷発生層および電荷輸送層をこの順に形成したものを用いて、電子写真感光体の誘電損失ｔａｎδ測定用サンプル２−１を作製した。 Next, 10 parts of an amine compound having a structure represented by the following formula, and

10 parts of polycarbonate resin (trade name: Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was dissolved in a mixed solvent of 30 parts of dimethoxymethane / 70 parts of chlorobenzene to prepare a coating solution for charge transport layer.
The charge transport layer coating solution was dip-coated on the charge generation layer and dried at a temperature of 120 ° C. for 30 minutes to form a charge transport layer having a thickness of 18 μm.
Thus, an electrophotographic photoreceptor 2-1 having a charge transport layer as a surface layer was produced.
Separately, a 50 μm aluminum foil is wound and fixed on the aluminum cylinder, and a conductive layer, an intermediate layer, a charge generation layer and a charge transport layer are formed in this order in the same manner as described above. A sample 2-1 for measuring dielectric loss tan δ of an electrophotographic photosensitive member was produced.

(Preparation of electrophotographic photoreceptor 2-2)
For measuring the dielectric loss tan δ of the electrophotographic photosensitive member 2-2 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid B. Sample 2-2 was produced.

(Preparation of electrophotographic photoreceptor 2-3)
For measuring dielectric loss tan δ of the electrophotographic photosensitive member 2-3 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid C. Sample 2-3 was produced.

(Preparation of electrophotographic photoreceptor 2-4)
For measuring dielectric loss tan δ of the electrophotographic photosensitive member 2-4 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid D. Sample 2-4 was produced.

(Preparation of electrophotographic photoreceptor 2-5)
For the measurement of dielectric loss tan δ of the electrophotographic photosensitive member 2-5 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid E. Sample 2-5 was produced.

(Preparation of electrophotographic photoreceptor 2-6)
Except for changing the coating liquid A for the conductive layer to the coating liquid F for the conductive layer, the dielectric loss tan δ of the electrophotographic photosensitive member 2-6 and the electrophotographic photosensitive member is measured in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-6 was produced.

(Preparation of electrophotographic photoreceptor 2-7)
For measuring dielectric loss tan δ of electrophotographic photosensitive member 2-7 and electrophotographic photosensitive member in the same manner as the production of electrophotographic photosensitive member 2-1, except that conductive layer coating liquid A is changed to conductive layer coating liquid G. Sample 2-7 was produced.

(Preparation of electrophotographic photoreceptor 2-8)
For measuring dielectric loss tan δ of electrophotographic photosensitive member 2-8 and electrophotographic photosensitive member in the same manner as the production of electrophotographic photosensitive member 2-1, except that conductive layer coating liquid A is changed to conductive layer coating liquid H. Sample 2-8 was produced.

(Preparation of electrophotographic photoreceptor 2-9)
Except for changing the coating liquid A for the conductive layer to the coating liquid I for the conductive layer, in the same manner as the production of the electrophotographic photosensitive member 2-1, for measuring the dielectric loss tan δ of the electrophotographic photosensitive member 2-9 and the electrophotographic photosensitive member. Sample 2-9 was produced.

(Preparation of electrophotographic photoreceptor 2-10)
Except that the conductive layer coating solution A is changed to the conductive layer coating solution J, the dielectric loss tan δ measurement of the electrophotographic photosensitive member 2-10 and the electrophotographic photosensitive member is performed in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-10 was produced.

(Preparation of electrophotographic photoreceptor 2-11)
For measuring dielectric loss tan δ of the electrophotographic photosensitive member 2-11 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid K. Sample 2-11 was produced.

(Preparation of electrophotographic photoreceptor 2-12)
Except that the conductive layer coating solution A is changed to the conductive layer coating solution L, the dielectric loss tan δ of the electrophotographic photosensitive member 2-12 and the electrophotographic photosensitive member is measured in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-12 was produced.

(Preparation of electrophotographic photoreceptor 2-13)
For measuring dielectric loss tan δ of the electrophotographic photosensitive member 2-13 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid M. Sample 2-13 was produced.

(Preparation of electrophotographic photoreceptor 2-14)
Except that the conductive layer coating solution A is changed to the conductive layer coating solution N, the dielectric loss tan δ of the electrophotographic photosensitive member 2-14 and the electrophotographic photosensitive member is measured in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-14 was produced.

(Preparation of electrophotographic photoreceptor 2-15)
For measuring the dielectric loss tan δ of the electrophotographic photosensitive member 2-15 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid O. Sample 2-15 was produced.

(Preparation of electrophotographic photoreceptor 2-16)
For measuring dielectric loss tan δ of the electrophotographic photosensitive member 2-16 and the electrophotographic photosensitive member in the same manner as the production of the electrophotographic photosensitive member 2-1, except that the conductive layer coating liquid A is changed to the conductive layer coating liquid P. Sample 2-16 was produced.

(Preparation of electrophotographic photoreceptor 2-17)
Except that the conductive layer coating solution A is changed to the conductive layer coating solution Q, the dielectric loss tan δ of the electrophotographic photosensitive member 2-17 and the electrophotographic photosensitive member is measured in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-17 was produced.

(Preparation of electrophotographic photoreceptor 2-18)
Except that the conductive layer coating solution A is changed to the conductive layer coating solution R, the dielectric loss tan δ of the electrophotographic photosensitive member 2-18 and the electrophotographic photosensitive member is measured in the same manner as the production of the electrophotographic photosensitive member 2-1. Sample 2-18 was produced.

(Examples 1 , 4, 7 , 18-21, Reference Examples 2, 3, 5, 6, 8-17, 22 and Comparative Examples 1-12)
Attach the charging roller and the electrophotographic photosensitive member produced by the above method to a laser beam printer HP Color LaserJet CP3505n Printer manufactured by HP Co., Ltd. in a modified machine so that the process speed can be changed, and 15 ° C / 10% A paper passing durability test was performed in an environment of RH, and images at the initial stage and after enduring 5000 sheets were evaluated. Further, another sample was prepared by the same method for the charging roller and the electrophotographic photosensitive member, and only the electrophotographic photosensitive member was stored for 30 days in an environment having a temperature of 55 ° C. and a humidity of 95 RH%. Attach the photoconductor to HP HP Laser LaserJet CP3505n Printer, a laser beam printer manufactured by HP, and perform a paper passing durability test in an environment of a temperature of 15 ° C./humidity of 10% RH. The image after paper durability was evaluated.

Details are as follows.
The HP Color LaserJet CP3505n Printer was modified to a process speed of 250 mm / s. Using this modified machine, the electrophotographic photosensitive member and the charging roller produced in the cyan color process cartridge of HP Color LaserJet CP3505n Printer were installed, and this cartridge was installed in the cyan process cartridge station for evaluation. . The electrophotographic photosensitive member and the charging roller described in Table 1 were used. Also, the type and coverage of the conductive metal oxide used in the conductive layer of the electrophotographic photosensitive member, the type of non-conductive inorganic particles, the number of rotations of the dispersion during adjustment of the coating solution for the conductive layer, and the electrophotographic apparatus used for the evaluation. The process speed is listed in Table 3. The nip width was measured when the electrophotographic photoreceptor and the charging roller were mounted. An example of a method for measuring the nip width is a method using carbon pressure sensitive paper.

  The method for measuring the nip width with carbon pressure sensitive paper is that when the electrophotographic photosensitive member and the charging roller are mounted on the process cartridge, the carbon pressure sensitive paper of about 25 μm is sandwiched in the nip portion, and the longitudinal direction of the charging roller is divided into five, This is a measurement method in which the width of the discolored portion at the corresponding location is measured, and the average value is the nip width. After measuring the nip width with carbon pressure sensitive paper, the electrophotographic photosensitive member and the charging roller are once removed from the process cartridge, and the electrophotographic photosensitive member and the charging roller are again attached to the process cartridge for evaluation. The measurement results of the nip width are shown in Table 2.

The volume resistivity of the charging roller used was measured according to the method for measuring the volume resistivity of the charging roller described above. Table 2 shows the measurement results of the volume resistivity of the charging roller.
When the paper was passed, a full color printing operation was performed in an intermittent mode in which two character images with a printing rate of 2% for each color were output on letter paper every 20 seconds, and 5000 images were output.
Then, three samples (one-dot Keima pattern halftone image) for image evaluation were output at the start of the durability test and after the end of 5000 sheets.
In addition, the evaluation of the image was performed under the environment of a temperature 15 ° C./humidity 10% RH after 30 days storage in a temperature 15 ° C./humidity 10% RH environment endurance test and a temperature 55 ° C./humidity 95 RH% environment. In the endurance test, the charging streaks were evaluated. The evaluation results are shown in Table 4.
The criteria for image evaluation are as follows.
The charging streaks were evaluated according to the following criteria for a halftone image with a 1-dot Keima pattern:
5: No charging streaks
4: Almost no charging streaks
3: Slightly charged streaks are observed,
2: Charging streaks are observed,
1: Charging streaks are clearly understood.

Further, the nip width between the charging roller and the electrophotographic photosensitive member in each example , reference example , and comparative example was measured as described above, and the following formula was obtained from the nip width and the process speed (mm / sec) of the electrophotographic apparatus. The dielectric loss tan δ of the electrophotographic photosensitive member at the frequency fHz obtained from (1) was measured according to the method for measuring the dielectric loss tan δ of the electrophotographic photosensitive member, using the dielectric loss tan δ measurement sample of the electrophotographic photosensitive member. Table 3 shows the measurement results.
f = P / X (1)
In the above formula (1), X represents the nip width (mm) between the charging roller and the electrophotographic photosensitive member, and P represents the process speed (mm / sec) of the electrophotographic apparatus.

(Examples 23 to 25, Reference Example 26)
The spring pressure of the spring that presses the charging roller against the electrophotographic photosensitive member was changed, and the nip width was changed as shown in Table 2. Further, the process speed of the laser beam printer HP Color LaserJet CP3505n Printer manufactured by HP was changed as shown in Table 1. Table 3 shows the process speed of the electrophotographic apparatus used for the evaluation. Evaluations were made in the same manner as in Example 1 except that the nip width and the process speed were changed. The results are shown in Tables 1-4.
As described above, the volume resistivity of the charging roller is 10 ¹⁰ Ωcm or more and 10 ¹² Ωcm or less, and the electrophotographic photosensitive member has a conductive layer, an intermediate layer, and a photosensitive layer in this order on the support, The conductive layer contains particles obtained by coating a conductive metal oxide with non-conductive inorganic particles, and the coverage of the conductive metal oxide is 10% by mass or more and less than 25% by mass with respect to the mass of the inorganic particles. In the electrophotographic apparatus in which the dielectric loss tan δ of the electrophotographic photosensitive member at the frequency fHz obtained from the above formula (1) is 0.020 or more and 0.500 or less, even after being stored under severe conditions from the beginning. It is possible to provide an electrophotographic apparatus in which image defects due to charged horizontal stripes do not occur until after durability.
As described in the examples, when the dielectric loss tan δ of the electrophotographic photosensitive member is 0.035 or more and 0.300 or less, it is more effective. Further, the dielectric loss tan δ of the electrophotographic photosensitive member is 0. In the case of 050 or more and 0.100 or less, the effect was more remarkable.
Even if the process speed of the electrophotographic apparatus is changed, the effect of the present invention can be obtained.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means (transfer roller)
7 Cleaning means (cleaning blade)
8 Fixing means 9 Process cartridge 10 Guide means P Transfer material (paper, etc.)
201 Charging member (charging roller)
201-1 surface layer 201-2 conductive elastic layer 201-3 support member (conductive support)
201-4 Pressure contact spring 202 Charged body (electrophotographic photosensitive member)
2 Charging roller 3 Charging bias application power source 15 Stainless steel cylindrical electrode 16 Resistance 17 Recorder

Claims (2)

In an electrophotographic photosensitive member having a conductive layer, an intermediate layer and a photosensitive layer in this order on a support, an electrophotographic apparatus having a charging means, an exposing means, a developing means and a transferring means
The charging means is contact charging means for charging the electrophotographic photosensitive member by applying only a DC voltage to a roller-shaped charging member brought into contact with the electrophotographic photosensitive member with a nip, and the roller-like charging member The volume resistivity of the charging member is 10 ¹⁰ Ωcm or more and 10 ¹² Ωcm or less,
The developing means is a contact developing means for performing development by bringing a developer carrying member carrying a developer into contact with the electrophotographic photosensitive member;
The conductive layer of the electrophotographic photoreceptor contains barium sulfate particles coated with oxygen-deficient tin oxide ;
The coverage of the tin oxide is more than 15 mass% 10 mass% or more by weight of the barium sulfate particles,
Dielectric loss tanδ of the electrophotographic photosensitive member in the frequency fHz obtained from the following equation (1) is 0.0 5 0 0 or more. 3 electrophotographic apparatus, wherein 00 or less:
f = P / X (1)
(In formula (1), X represents the nip width (mm) between the roller-shaped charging member and the electrophotographic photosensitive member, and P represents the process speed (mm / sec) of the electrophotographic apparatus. ). The dielectric loss tanδ is, electrophotographic apparatus according to claim 1 is 0.050 0.100.

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