JP2009009028A - Contact type charging member, process cartridge, and electrophotographic image forming apparatus - Google Patents

Abstract

Disclosed is a charging member having excellent durability by suppressing generation of an image caused by dirt and an image caused by defective discharge even after repeated use over a long period of time, a process cartridge using the same, and an electrophotographic image forming apparatus. provide.
A charging member for contact charging, comprising a conductive support, and a surface layer c containing a binder resin and a conductive agent, and having conductivity imparted by the conductive agent, the surface layer c further comprising: And rough particles RP dispersed in the binder resin. The rough particles RP contains a layered compound selected from boron nitride, silicon nitride, molybdenum disulfide and tungsten disulfide, and has an average particle diameter of 1 μm. A charging member in which the surface layer c has a convex portion derived from the inclusion of the roughened particles RP on the surface, and the charging member has a surface roughness Rzjis of 3 μm or more and 20 μm or less, , Process cartridge and electrophotographic image forming apparatus using the same.
[Selection] Figure 1

Description

  The present invention relates to a charging member, a process cartridge using the charging member, and an electrophotographic image forming apparatus. More specifically, the present invention relates to a charging member that suppresses generation of ozone and has excellent durability even under a high voltage application condition, and a process cartridge and an electrophotographic image forming apparatus that can obtain a good image using the charging member.

  An electrophotographic image forming apparatus adopting an electrophotographic system has an electrophotographic photosensitive member, a charging unit for charging the photosensitive member, and an exposing unit for forming an electrostatic latent image on the surface of the charged photosensitive member by exposure. Further, the electrophotographic image forming apparatus includes a developing unit that supplies developer (toner) to the electrostatic latent image formed on the surface of the photoreceptor, a transfer unit that transfers the developer onto a recording material (paper), and the transferred image. In general, fixing means for fixing a developer on a recording material to form an image on the recording material is provided.

  As a charging means in such an electrophotographic image forming apparatus, a method of charging the surface of the photoconductor by applying a voltage to a charging member placed in contact with or close to the surface of the electrophotographic photoconductor is often employed. ing. Contact-type charging means are frequently used from the viewpoints of charging stability of a photoreceptor to be charged, reduction of ozone generation, or cost reduction.

  As the applied voltage, only a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage is used. Specifically, a DC voltage (DC voltage) obtained by adding a required photoreceptor surface potential Vd to a discharge start voltage (about 550 V when the charging roller is pressed against the photoreceptor). There is a DC charging method in which charging is performed by application. Further, charging is performed by applying to the contact charging member a voltage obtained by superimposing an AC component (AC component) having a peak-to-peak voltage more than twice the discharge start voltage on a DC voltage corresponding to the required photoreceptor surface potential Vd. There is an AC charging method for performing the above. From the viewpoint of downsizing and energy saving of the electrophotographic image forming apparatus, it is preferable that the voltage applied to the charging member is only a DC voltage (DC charging method).

However, the DC charging method has a narrower discharge area than the AC charging method and does not have the effect of leveling the AC discharge current. Therefore, the charging uniformity is maintained due to minute resistance value unevenness of the charging member and other factors. There was a problem that it was difficult to do.
For example, an image due to streak-like or spot-like stains may occur, and this tendency becomes remarkable with long-term repeated use. This is promoted in environmental conditions where the discharge phenomenon is unlikely to occur, such as low temperature and low humidity.

As a method for stabilizing charging, a method is known in which the surface of the charging member in contact with the member to be charged is roughened to increase the discharge point, thereby improving the charging efficiency and uniform charging property for the member to be charged. (Patent Document 1). However, in this method, due to the nature that the charging member is in contact with the member to be charged, fine toner, external additives, etc. adhering to the member to be charged easily adhere to the surface of the charging member due to irregularities on the surface of the charging member. The surface is easily contaminated. As a result, a partial increase in resistance due to adhering substances occurs, so that charging failure tends to occur.
In particular, in recent years, along with the demand for higher image quality, the demand for longer life and colorization has increased, and in particular, the target life value of process cartridges including charging rollers has been increasing significantly, and contamination resistance of charging rollers is required. ing.
JP-A-7-281507

  An object of the present invention is to provide a charging member excellent in durability capable of outputting a good image by suppressing generation of an image caused by dirt and an image caused by defective discharge even after repeated use over a long period of time. There is to do. Another object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus using the charging member.

  The charging member according to the present invention is a charging member for contact charging including a conductive support, a binder resin and a conductive agent, and having a surface layer imparted with conductivity by the conductive agent. Furthermore, it includes rough particles dispersed in the binder resin, and the rough particles include a layered compound selected from boron nitride, silicon nitride, molybdenum disulfide, and tungsten disulfide, and an average particle diameter of 1 μm or more. The surface layer has a convex portion derived from the inclusion of the roughened particles on the surface, and the surface roughness Rzjis of the charging member is 3 μm or more and 20 μm or less.

  The convex portion of the surface layer derived from the inclusion of the rough particles causes a gap in the nip portion with the member to be charged.

  The rough particles are composite particles obtained by coating the surface of mother particles with child particles selected from the layered compound, and the mother particles are composed of resin particles or inorganic particles.

  The conductive member has a surface layer formed by dispersing the roughened particles and the conductive agent in at least a binder resin on a conductive support, and the surface layer includes the roughened particles and the conductive agent. It is a coating film formed by applying the added paint.

  The process cartridge according to the present invention is characterized in that the charging member and the member to be charged are integrated, and is detachable from the main body of the electrophotographic image forming apparatus.

  An electrophotographic image forming apparatus according to the present invention includes at least the process cartridge, an exposure unit, and a transfer unit.

  The electrophotographic image forming apparatus is characterized in that only a DC voltage is applied to the charging member to charge the member to be charged.

The layered compound constituting the rough particles of the present invention has an action of suppressing dielectric loss. By forming such convex portions derived from the inclusion of rough particles on the surface of the surface layer of the charging member, it is possible to suppress the occurrence of an image due to contamination and an image due to defective discharge even by repeated use. In addition, it is possible to obtain a charging member excellent in durability capable of suppressing generation of a charged horizontal streak image and an uneven charging image and outputting a good image.
Furthermore, by making the rough particles of the present invention into composite particles, the effect of suppressing dielectric loss is enhanced, and the above-mentioned effects are maintained for a longer period due to the minute unevenness of the particle surface caused by the composite particles. Is done.

The charging member for contact charging in the present invention includes a conductive support, a surface layer that includes a binder resin and a conductive agent, and is given conductivity by the conductive agent. The surface layer further includes rough particles dispersed in the binder resin, and the rough particles contain a layered compound. The surface layer has a convex portion derived from the inclusion of the rough particles on the surface.
Furthermore, the roughening particles are composite particles obtained by coating the surface of mother particles with child particles selected from the layered compound, and the mother particles are composed of resin particles or inorganic particles. FIG. 1 shows the structure of the surface layer when the charging member having convex portions derived from the rough particles of the present invention is used as a charging member for contact charging.

The inventor observed the discharge state of the charging member for the purpose of analyzing streaky charging failure in the DC charging system. As a result, the charging member having a smooth surface that does not contain roughening particles only discharges in the gaps on both sides of the nip portion with the photoreceptor. However, it has been confirmed that in the charging member in which the convex portion is formed by rough particles, discharge occurs in the nip in addition to the discharge on both sides of the nip portion with the photoreceptor.
The inventors have found that the formation of convex portions on the surface of the charging member is effective for suppressing streaky charging failure in DC charging. This is considered to be an effect of the discharge in the nip. That is, even when the charge generated in the gap on the upstream side of the nip portion becomes non-uniform, it is presumed that there is a leveling action by the discharge in the nip.
As described above, the effect of the present invention is exhibited by the discharge in the gap upstream and downstream of the nip portion with the photosensitive member and the in-nip discharge by the convex portion.

  In the present invention, it is preferable that the convex portion of the surface layer derived from the inclusion of roughened particles causes a gap in the nip portion with the member to be charged. This is because the presence of voids due to the convex portions causes discharge even in the voids and enables more uniform charging.

The layered compound contained in the rough particles of the present invention is selected from boron nitride, silicon nitride, molybdenum disulfide and tungsten disulfide. The surface of the surface layer of the charging member has a convex portion derived from the inclusion of the rough particles of the layered compound of the present invention, and the convex portion is configured to generate a gap in the nip portion with the member to be charged. The ten-point average surface roughness (Rzjis) is controlled to 3 μm or more and 20 μm or less.
If the 10-point average surface roughness (Rzjis) of the charging member is less than 3 μm, it becomes difficult to stably control the discharge, and a charging unevenness image with uneven charging properties (unevenness) may occur. Further, when the charging member has a ten-point average surface roughness (Rzjis) exceeding 20 μm, the unevenness of the charging member becomes large, so that an image due to defective discharge may occur.
Here, the ten-point average surface roughness is a measurement value obtained by measuring the ten-point average surface roughness at six random points of the charging member according to JISB0601. The measurement was performed using a surface roughness measuring instrument “SE-3400” (manufactured by Kosaka Laboratory Ltd.).

  The average particle diameter of the layered compound is 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less. When the average particle diameter of the rough particles is less than 1 μm, even if the rough particle content in the surface layer is increased, it is difficult to adjust the surface roughness, and the generation of images due to defective discharge is sufficiently suppressed. I can't. On the other hand, if it exceeds 30 μm, the occurrence of an image caused by dirt or an image caused by overdischarge may not be sufficiently suppressed. If this exceeds 30 μm, it is presumed that excessive point discharge tends to be induced, and discharge control becomes difficult. Here, the average particle diameter of the roughened particles is obtained by observing 1000 secondary aggregated particles only with a transmission electron microscope (TEM), obtaining the projected area, and calculating the equivalent circle diameter of the obtained area. Thus, the volume average particle diameter can be obtained and obtained as the average particle diameter. The particle size distribution is a distribution as the volume average particle diameter.

The layered compound of the present invention selected from boron nitride, silicon nitride, molybdenum disulfide, and tungsten disulfide has a tendency to suppress the frictional force of the convex portion due to the inclusion of roughened particles due to lubricity. The dirt of the part can be controlled. In addition, even when the binder layer that covers the surface due to repeated use is scraped off, the release effect is exhibited and the stains are less likely to accumulate, thereby suppressing the occurrence of images due to the stains. Can do.
In addition, the layered compound of the present invention selected from boron nitride, silicon nitride, molybdenum disulfide, and tungsten disulfide suppresses dielectric loss and improves charging ability, so that generation of an image due to defective discharge can be particularly suppressed. it can.

  The blending amount of the roughened particles of the present invention is preferably 2 to 120 parts by mass, more preferably 5 to 100 parts by mass, and further preferably 5 to 60 parts by mass with respect to 100 parts by mass of the binder resin described later. . The formation of the convex portion derived from the inclusion of the rough particles of the present invention can be performed, for example, by adjusting the blending ratio with the binder resin, the average particle diameter of the rough particles, the film thickness of the surface layer, and the like. Here, when the content is less than 2 parts by mass, it becomes difficult to form irregularities on the surface. If the content exceeds 120 parts by mass, it may be difficult to control the surface roughness.

  The rough particles of the present invention are more preferably composite particles in which the surface of the mother particle is coated with the layered compound as a child particle. This is because the compounding causes a difference in the dielectric constant between the layered compound (child particles) and the mother particles, thereby increasing the electrostatic capacity and further improving the charging ability.

In the composite particles of the present invention, the mother particles are made of resin particles or inorganic particles.
Examples of the resin particles include nylon, polyethylene, polypropylene, polyester, polystyrene, polyurethane, styrene-acrylic copolymer, polymethyl methacrylate, epoxy resin, phenol resin, melamine resin, cellulose, polyolefin, silicone powder, and the like.
Examples of the inorganic particles include silicon oxide such as silica, aluminum oxide, titanium oxide, zinc oxide, calcium carbonate, magnesium carbonate, aluminum silicate, strontium silicate, barium silicate, calcium tungstate, clay mineral, mica, Examples include talc and kaolin. Among these, resin particles and inorganic silicon oxide are preferred as the difference between the laminar compound and the dielectric constant when composite particles are used.

The shape of the mother particles is not particularly limited, but is preferably spherical.
The average particle size of the mother particles used is not particularly limited as long as the average particle size as rough particles is controlled to 1 μm or more and 30 μm or less, but is preferably 1 μm or more and 25 μm or less. When the average particle diameter is smaller than 1 μm, it becomes difficult to coat the layered compound. The average particle diameter of the layered compound covering the mother particles is not particularly limited, but is preferably 0.005 to 5 μm, and more preferably 0.1 to 3 μm. When the average particle diameter is in this range, the coverage to the mother particles is improved. The average particle diameter is represented by an equivalent circle diameter having the same area as the plane area.

  The coating amount of the layered compound on the mother particles varies depending on the conditions (shape, particle size, type) of the mother particles and is not particularly limited, but is preferably 5 to 70% by mass. If the amount is less than 5% by mass, the characteristics of the composite particles of the present invention are hardly exhibited. If the amount is more than 70% by mass, more particles may fall off the mother particles.

Examples of the method for obtaining the composite particles of the present invention include the following methods.
When the mother particles are resin particles composed of an organic soft material such as nylon or silicone, the mother particles and the layered compound are mixed in the above-mentioned mixing ratio, and the mother force is mainly generated by electrostatic force by utilizing the caustic phenomenon. Adhere to the surface of the particles. Subsequently, in order to strengthen the bond with the mother particles, an impact is applied in a high-speed air stream. By such treatment, a part of the surface of the polymer constituting the mother particle is softened and is firmly bonded by embedding the layered compound. As a device for forcibly applying a physical force, a well-known composite device such as a high-speed jet airflow crusher, a hybridizer, or a mechanofusion is used.

  In addition, when the mother particles are inorganic particles composed of an inorganic hard material such as silicon oxide, a solvent containing a dispersant for mixing both in the above-described mixing ratio and further uniformly dispersing the mixture, For example, water is added to form a suspension, which is sufficiently dispersed by stirring and mixing. This suspension is sprayed through a pressure spray nozzle under hot air. At this time, the solvent of the suspension evaporates in the process of spraying the mist suspension, and the layered compound is attached to the surface of the mother particle. Further, in order to remove the remaining solvent and calcinate, it is treated in an inert gas atmosphere, for example, in a nitrogen atmosphere. As an apparatus for performing the operation, for example, a spray dry spray dryer is used.

(Embodiment of charging member)
The charging member of the present invention comprises a conductive support, a conductive elastic layer, a surface layer, and the like.
Examples of the conductive support include metals such as iron, copper, stainless steel, aluminum, nickel, and alloys thereof. For the purpose of imparting scratch resistance to these surfaces, plating treatment or the like may be performed as long as the conductivity is not impaired. The shape of the conductive support determines the shape of the charging member, and examples thereof include a cylinder, a column, a flat plate, a blade, a belt, a sheet, and a film.
The conductive elastic layer is provided on the conductive support and is provided for imparting conductivity, elasticity and the like to the charging member so that the surface of the photoreceptor can be uniformly charged.

The shape of the charging member of the present invention is preferably a roller shape, but may be a sheet shape, a belt shape, a film shape, a plate shape, or the like.
The charging member formed on the roller-shaped electroconductive support body a is shown. 2 has one surface layer c, and FIG. 3 has two layers, a conductive elastic layer b and a surface layer c formed on the conductive elastic layer b. 4 shows a conductive elastic layer b, a resistance layer d, and a surface layer c. FIG. 5 shows a conductive elastic layer b, a resistance layer d, a second resistance layer e, and a surface layer c. The thing which has these 4 layers can be mentioned.
The charging member formed on the flat conductive support a1 is shown. 6 has one outermost layer c1, and FIG. 7 has two layers of a conductive elastic layer b1 and a surface layer c1 formed on the conductive elastic layer b1.
The charging member formed on the belt-shaped conductive support a2 is shown. 8 has one outermost layer c2, and FIG. 9 has two layers of a conductive elastic layer b2 and a surface layer c2 formed on the conductive elastic layer b2.

(Surface layer)
As the binder used for the surface layer, a known binder can be employed. For example, a resin, natural rubber, a vulcanized product thereof, a rubber such as a synthetic rubber, an elastomer such as a thermoplastic elastomer, and the like can be given.
Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC), and olefin-ethylene-butylene-olefin copolymer (CEBC). Etc.
Examples of the synthetic rubber include ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile-butadiene copolymer rubber (NBR). ), Chloroprene rubber (CR), acrylic rubber and epichlorohydrin rubber.
Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, fluororubber-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, Examples thereof include an ethylene vinyl acetate thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, and a chlorinated polyethylene thermoplastic elastomer.
These binders may be used alone or in combination of two or more as a mixture or copolymer. Among these, it is preferable to use a resin.

In addition to the rough particles of the present invention, the surface layer may contain conductive fine particles as a conductive agent.
Examples of the conductive fine particles include metal oxide conductive fine particles, metal conductive fine particles, carbon black, and carbon conductive fine particles. These may be used alone or in combination of two or more.
Examples of carbon black include furnace black, ketjen black, and channel black. Examples of the metal oxide-based and metal-based conductive fine particles include particles of tin oxide, titanium oxide, zinc oxide, barium sulfate, copper, aluminum, nickel, and the like. Examples of the carbon conductive fine particles include composite conductive fine particles in which metal oxide particles are coated with carbon black.

  Carbon black tends to be difficult to be present uniformly with respect to the binder because the particles are arranged in a bead shape. For this reason, by using carbon black as a composite conductive fine particle coated with a metal oxide, it can be made to exist uniformly in the binder, and the volume resistivity tends to be easily controlled.

  The composite conductive fine particles can be easily and uniformly dispersed in the binder by using metal oxide-based particles such as metal oxide or composite metal oxide. Examples of the metal oxide fine particles include zinc oxide, tin oxide, indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.), iron oxide, silica, alumina, magnesium oxide, zirconium oxide, strontium titanate, calcium titanate, Examples thereof include magnesium titanate, barium titanate, and calcium zirconate.

  The metal oxide fine particles are preferably surface-treated. Thereby, the metal oxide fine particle surface and carbon black can be adhered more firmly. As the surface treatment, preferably one or two of various coupling agents, oligomers or polymer compounds of organosilicon compounds such as alkoxysilane, fluoroalkylsilane, polysiloxane, silane, titanate, aluminate and zirconate The above can be used.

  As the carbon black coated on the metal oxide fine particles, furnace black, ketjen black, channel black and the like are preferable. These may be used alone or in combination of two or more. The adhesion amount of carbon black is preferably 1 to 500 parts by mass with respect to 100 parts by mass of the metal oxide particles.

As for the thickness of the said surface layer, 1-100 micrometers is preferable. More preferably, it is 2-50 micrometers.
The film thickness can be determined by cutting the produced charging member with a cutter knife or the like, observing the cross section of the layer with an optical microscope or an electron microscope, and measuring the thickness.

The surface layer is not particularly limited as long as it is a suitable method for forming a suitable layer thickness, and can be prepared using a known method in forming a resin compound layer. Among them, a method of forming a coating film by applying a paint is preferable.
As a method for forming such a surface layer, the material constituting the surface layer is dispersed by a known method using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill. Next, the obtained coating material for forming the surface layer is applied using coating means such as electrostatic spraying, dipping, roll coater, coil coater, curtain flow coater, electrodeposition coating, electrostatic coating, powder coating, etc. Thus, the surface layer can be formed. Considering the utilization efficiency of the surface layer paint, the dipping method is more preferable.

  When using electrostatic spraying or dipping, various solvents are often used. The solvent to be used is not particularly limited, but it is necessary to use a solvent in which the binder to be used is easily dissolved. Specifically, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, Ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, ethylene chloride, dichloroethylene, carbon tetrachloride and trichloroethylene, or benzene, toluene, Aromatic compounds such as xylene, ligroin, chlorobenzene and dichlorobenzene are used.

(Conductive elastic layer)
Examples of the conductive elastic layer include elastomers such as the synthetic rubber and thermoplastic elastomer exemplified above for imparting elasticity. Synthetic rubber is more preferable from the viewpoint of securing a sufficient nip between the charging member and the photosensitive member. Further, when a polar rubber is used as the synthetic rubber, the resistance can be easily made uniform. Examples of the polar rubber include NBR and epichlorohydrin rubber.

  Examples of the epichlorohydrin rubber include GECO (ethylene oxide (hereinafter also referred to as EO) -epichlorohydrin (hereinafter also referred to as EP) -allyl glycidyl ether (hereinafter also referred to as AGE) copolymer) and ECO (ethylene oxide-epichlorohydrin copolymer). Can be mentioned. In GECO and ECO, it is known that the volume resistivity can be controlled by changing the copolymerization ratio of EO.

The volume resistivity of the conductive elastic layer is preferably 10 ² to 10 ¹⁰ Ω · cm under a 23 ° C./50% RH environment.
The volume resistivity of the conductive elastic layer can be adjusted by appropriately adding a conductive agent such as carbon black, conductive metal oxide, alkali metal salt, or ammonium salt to the conductive elastic layer material. . When using polar rubber, it is preferable to use an ammonium salt.

In order to adjust the hardness and the like of the conductive elastic body layer, additives such as softening oil and plasticizer may be added.
When an additive is used for the conductive elastic layer, one or two or more resistance layers are provided between the conductive elastic layer and the surface layer from the viewpoint of enhancing the prevention of bleed out of the additive. Also good.

  The conductive elastic layer can be formed, for example, by adhering or covering a sheet-shaped or tube-shaped layer formed in advance with a predetermined film thickness. Further, formation by extrusion molding, formation of a shape by polishing, etc., molding into a predetermined shape in a mold, and the like can also be performed.

(Electrophotographic image forming apparatus)
The electrophotographic image forming apparatus of the present invention is not particularly limited as long as it has an electrophotographic photosensitive member, the charging member, an exposure unit, a developing unit, and a transfer unit. As an example, an electrophotographic image forming apparatus shown in the schematic configuration diagram of FIG.
The electrophotographic image forming apparatus shown in FIG. 10 is provided with a cylindrical photosensitive member 151 having a diameter of 24 mm, which is a member to be charged. The photosensitive member 151 is driven to rotate in the direction of the arrow at a process speed of 250 mm / s. To do. For example, a charging roller 153 which is a charging member that is brought into contact with and abuts on the photoreceptor 151 with a pressing force of a spring of 4.9 N (0.5 kg weight) at one end and a total weight of 9.8 N (1 kg weight) at both ends. Is provided. The charging roller rotates in the forward direction with respect to the rotation of the photoreceptor 151. A power supply S1 that applies only a DC voltage is connected to the charging roller, and the surface of the photoreceptor 151 is charged to about −400 V by applying a DC voltage of −1000 V, for example, from the power supply S1 to the charging roller 153. It is to be processed (contact charging).

  The electrophotographic image forming apparatus is provided with an exposure device 154 such as a laser beam scanner. Exposure (image exposure) light 154 </ b> L corresponding to target image information is irradiated by the laser beam scanner 154 onto the surface of the photoreceptor 151 charged to −400 V (dark portion potential) by the charging roller 153. As a result, the potential of −400 V on the surface of the photoreceptor is selectively attenuated to −150 V (bright part potential), and an electrostatic latent image is formed on the surface of the photoreceptor 151.

  A developing device 155 is further provided around the photoreceptor 151. The developing device 155 includes a developing member 155a that is disposed in an opening of a developing container that contains toner and carries and conveys the toner, an agitating member 155b that stirs the contained toner, and a toner carrying amount (toner) of the developing member 155a. A toner regulating member 155c for adjusting the layer thickness) is provided. In the developing device 155, a toner (negative toner) charged to −350 V (developing bias) is selectively attached to a bright portion potential portion of the electrostatic latent image formed on the surface of the photoreceptor 151, thereby electrostatically The latent image is visualized as a toner image. In this electrophotographic image forming apparatus, a contact developing method is adopted in which the developing member 155a is in contact with the photosensitive member or is in contact with the photosensitive member via the toner to be carried.

  Further, a transfer member 156 is provided. The transfer member 156 is a transfer member formed by coating an elastic resin layer adjusted to a medium resistance on a conductive support. This is arranged so as to contact the photoconductor 151 with a transfer nip portion with a predetermined pressing force, and the transfer member has a circumferential speed substantially the same as the rotational circumferential speed of the photoconductor 151 in the forward direction with the rotation of the photoconductor 151. It is designed to rotate at. A transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer member from the power source S2. A transfer roller 156 to which a transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the back surface of the transfer material P supplied at a predetermined timing from a paper feed mechanism (not shown) is pressed against the transfer nip portion. Is done. As a result, the toner image is electrostatically transferred from the surface of the photoreceptor 151 to the surface of the transfer material P (paper, film, etc.).

  Further, a fixing device (not shown) is provided, and the toner image transferred onto the transfer material P is fixed on the transfer material P by heating or the like, and the transfer material P on which the toner image is fixed is used as an image formed product. Is output. In the case of the double-sided image forming mode or the multiple image forming mode, the image formed product is introduced into a recirculation conveyance mechanism (not shown) and reintroduced into the transfer nip portion.

  Further, a cleaning device (not shown) provided with a cleaning blade or the like is provided, and after the transfer residual toner on the surface of the photoconductor 151 is collected by the cleaning device, the photoconductor 151 is again in an image forming state, and The operation is repeated.

  The process cartridge of the present invention is not particularly limited as long as the photosensitive member and the charging member are integrated and detachable from the main body of the electrophotographic image forming apparatus. As an example, among the configurations of the photoconductor 151, the charging member 153, the developing device 155, the transfer member 156, etc. of the electrophotographic image forming apparatus shown in FIG. An example of the process cartridge is a cartridge that can be attached to and detached from the electrophotographic image forming apparatus main body using guide means such as a rail of the electrophotographic image forming apparatus main body. This process cartridge is configured to be detachable from an electrophotographic image forming apparatus main body such as a copying machine or a laser beam printer.

The photoreceptor 151 includes, for example, a cylindrical conductive support, and a photosensitive layer containing an inorganic photosensitive material and / or an organic photosensitive material formed on the support. It may further have a charge injection layer for charging to a predetermined polarity and potential.
As shown in FIG. 11, the specific structure of the photoreceptor 151 includes a conductive support 1a and a photosensitive layer 1b formed on the conductive support 1a. For the photosensitive layer 1b, a structure in which a charge generation layer 11b and a charge transport layer 12b are laminated as shown in the figure can be preferably used.

  The photoreceptor may have layers other than those described above. As shown in FIG. 12, the conductive support 1a, the undercoat layer 1c formed on the conductive support 1a, A structure having a photosensitive layer 1b formed on the undercoat layer 1c can be used.

  As the developing device 155, for example, a jumping developing method, a contact developing method, a magnetic brush method, or the like can be adopted.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the technical scope of the present invention is not limited thereto.
In the manufacturing examples shown below, the charging member has a roller shape composed of a conductive support, a conductive elastic layer, and a surface layer.

[Production example]
(1) -1 Production Example 1 Conductive Elastic Layer (Conductive Elastic Roller)
The following compounds were added to 100 parts by mass of epichlorohydrin rubber (trade name: “Epichromer CG105”, manufactured by Daiso Corporation), and kneaded with an open roll for 30 minutes.
MT carbon (filler, trade name: “N991”, manufactured by Thermax) 35 parts by mass Zinc oxide 5 parts by mass Stearic acid 1 part by mass The following compounds were further added to the kneaded product and kneaded with an open roll for 15 minutes. . Thereby, kneaded material I was obtained.
Di-2-benzothiazolyl disulfide (vulcanization accelerator, trade name: “Noxeller DM-P”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass Tetramethylthiuram monosulfide (vulcanization accelerator, trade name) : “Noxeller TS”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by mass Sulfur (vulcanizing agent) 1.2 parts by mass

  Next, the kneaded product I was extruded into a cylindrical shape having an outer diameter of 9.5 mm and an inner diameter of 5.4 mm with a rubber extruder, cut into a length of 250 mm, and steamed at 160 ° C. for 30 minutes with a vulcanizing can. By performing the subsequent vulcanization, a primary vulcanization tube for a conductive elastic body layer was obtained.

  On the other hand, a thermosetting adhesive containing a metal and a rubber (trade name: “Metallock U-20”) (on a surface of nickel-coated steel column having a diameter of 6 mm and a length of 256 mm) Co., Ltd. manufactured by Toyo Chemical Laboratory Co., Ltd. was applied. The application was performed on a region of up to 115.5 mm on both sides across the center in the axial direction of the cylindrical surface of the support (a region with an axial width of 231 mm). This was dried at 80 ° C. for 30 minutes, and further dried at 120 ° C. for 1 hour.

  The support coated with the thermosetting adhesive and dried is inserted into the primary vulcanization tube for the conductive elastic layer, and then the primary vulcanization tube for the conductive elastic layer is placed for 160 hours. Heated at ° C. By this heating, the primary vulcanized tube for the conductive elastic layer was secondarily vulcanized, and the thermosetting adhesive was cured. In this way, a conductive elastic layer before surface polishing was obtained.

  Next, both ends of the conductive elastic layer portion (rubber portion) of the conductive elastic roller before surface polishing were cut, and the axial width of the conductive elastic layer portion was 231 mm. Then, the surface of the electroconductive elastic-body layer part was grind | polished with a rotating grindstone, and the electroconductive elastic roller 1 (The electroconductive elastic roller after surface grinding | polishing) was obtained. The conductive elastic roller had a crown shape with an end diameter of 8.2 mm and a center diameter of 8.5 mm, a surface Rzjis of 2.5 μm, and a hardness of 74 degrees (Asker C).

(1) -2 Production Examples 2 to 8, C1 to C4 conductive elastic layer (conductive elastic roller)
Conductive elastic rollers 2 to 8 and C1 to C4 were produced in the same manner as in Production Example 1 of the conductive elastic layer (conductive elastic roller).

(2) -1 Production Example 1 Roughened particles 1.0 kg of tungsten disulfide, which is a layered compound, was cooled and solidified to form a pellet, and the mixture was uniformly mixed by a double cone rotary mixer and then freeze-pulverized. Thereafter, particles that passed through a mesh having a mesh size of 15 μm and that did not pass through a mesh having a mesh size of 8 μm were collected to obtain tungsten disulfide particles having an average particle size of 11.5 μm (coarse particles 1).

(2) -2 Production Examples 2 to 4, C1 to C4 Roughened Particles Similar to Roughened Particle Production Example 1 except that the layered compound was changed as shown in Table 1 and the size of the mesh to be passed was changed. Thus, coarse particles 2 to 4 and C1 to C4 were produced.

(2) -3 Production Example 5 Coarse particles Production of nylon-boron nitride composite particles:
70 g of nylon base particles having an average particle size of about 5 μm and 30 g of boron nitride powder (h-BN, average particle size: 1 μm) are placed in a ball mill, mixed for 30 minutes, and boron nitride powder on the surface of the base particles by electrostatic force. Was adhered uniformly. Furthermore, in order to further strengthen the bond between the mother particles and the boron nitride powder, the mixed particles are introduced into the grinding chamber of a high-speed jet airflow crusher, and friction and collision between the particles are caused by a high-speed jet jet of 200 m / second. Then, boron nitride powder was embedded in the surface of the mother particles. The composite particles rise in the pulverization chamber, and are collected through a classifier. The particles that pass through a mesh with an opening of 12 μm and do not pass through a mesh with an opening of 5 μm are collected, and the average particle size is 8.4 μm. Nylon-boron nitride composite particles were obtained (roughened particles 5).

(2) -4 Production Examples 6-8 Roughened Particles The same procedure as in Roughened Particles Production Example 5 except that the mother particles and child particles were changed as shown in Table 1 and the size of the mesh to be passed was changed. Thus, coarse particles 6 to 8 were produced.

(3) -1 Production Example 1 Surface Layer Solution As the surface layer solution, a mixed solution of the following compounds was prepared.
Caprolactone-modified acrylic polyol solution (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) 100 parts by weight Methyl isobutyl ketone 312 parts by weight Roughened particles 1 prepared in Production Example 1 50 parts by weight Conductive tin oxide (trade name: 150 parts by weight modified dimethyl silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) 0.08 parts by weight HDI nurate block body and IPDI nurate block body ( 7: 3 mixture) 80.14 parts by mass At this time, the mixture of HDI and IPDI is (isocyanate group of mixture of HDI and IPDI) / (hydroxyl group of the acrylic polyol) = 1.0. For HDI and IPDI, HDI nurate (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Kogyo) and IPDI nurate (trade name: Bestanat B1370, manufactured by Degussa Huls) were used.
In a 450 mL glass bottle, 210 g of the above mixed solution and 200 g of glass beads having an average particle diameter of 0.8 mm as media were mixed and dispersed for 36 hours using a paint shaker disperser to obtain a surface layer solution 1.

(3) -2 Production Examples 2-8, C1-C4 Surface Layer Solution A surface layer was produced in the same manner as in Production Example 1 of the surface layer solution except that the roughened particles were coarsened and changed to particles 2-8, C1-C4. Solutions 2-8, C1-C4 were prepared.

(4) -1 Production Example 1 Charging Member The surface layer solution 1 obtained in Production Example 1 of the surface layer solution was dipped on a conductive elastic roller once, air-dried at room temperature for 30 minutes or more, and then heated to 80 ° C. It dried for 1 hour with the set hot-air circulation dryer. Furthermore, it dried with the hot air circulation dryer set to 160 degreeC for 1 hour, and formed the surface coating layer on the electroconductive elastic roller. The dipping coating dipping time is 9 seconds, the dipping coating lifting speed is adjusted so that the initial speed is 20 mm / s, and the final speed is 2 mm / s. Between 20 mm / s and 2 mm / s is linear with respect to time. The speed was changed.
Thus, the charging member 1 was produced. Table 1 shows the physical properties of the manufactured charging member.

(4) -2 Production Examples 2 and 4-8, C1-C4 Charging Member Production was carried out in the same manner as in Charging Member Production Example 1, and charging members 2 and 4-8, C1-C4 were produced. Table 1 shows the physical properties of the manufactured charging member.

(4) -3 Production Example 3 Charging member Instead of the dipping method, the conductive elastic roller 3 was put, the surface layer solution 3 was cast on the outer periphery thereof, and air-dried at room temperature for 30 minutes or more. Next, the mold is dried for 1 hour with a hot air circulating dryer set at 80 ° C, and further dried with a hot air circulating dryer set at 160 ° C for 1 hour, and cooled to room temperature. The charging member 3 was manufactured by demolding. Table 1 shows the physical properties of the manufactured charging member.

Example 1
The charging member 1 was evaluated as follows.
[Durable image evaluation (contamination resistance evaluation)]
The manufactured charging member was mounted on the electrophotographic image forming apparatus having the configuration shown in FIG. 10, and 100 solid images were output to make the charging member dirty. Thereafter, after replacing the developing device and the cleaning device, one image was output, the rotation of the electrophotographic image forming apparatus was stopped, and the image forming operation was resumed. The above operation was repeated (E character 1% printed image was intermittently endured), and an image output endurance test for 5000 sheets was performed.
The evaluation condition is that an electrophotographic photosensitive drum having a diameter of 24 mm is contacted by a spring pressure of 4.9 N (0.5 kg weight) at one end and a total of 9.8 N (1 kg weight) at both ends, and a DC voltage is applied to the charging member. Only -1000V was applied and durability evaluation was performed in a 23 degreeC / 50% RH environment. The toner used was a polymerized toner having an average particle diameter of 5.0 μm, and the electrophotographic photosensitive drum was a photosensitive drum mounted on a monochrome (black) cartridge of a trade name: “HP Color LaserJet 3000” (manufactured by Hewlett-Packard). . During the durability test, the process speed was set to 250 mm / s, a halftone image was used, and the output image was evaluated for an image defect due to dirt according to the following rank criteria.
Rank A: Not generated Rank B: Minor generation of streak-like or spot-like images at the end Rank C: Some streaky-like or potty-like images are generated, but there is no problem in actual use Rank D: Streaks The image quality is inferior in several places, and the image quality is inferior. Rank E: The image in the form of streaks and in the shape of a spot appears in the entire image, and the image quality is greatly inferior. As a result, as shown in Table 2. A slight streak-like image was generated at the end, but it was at a level where there was no problem in practical use.

[Durability image evaluation (discharge evaluation)]
The charging member after outputting 5000 images obtained by the contamination evaluation described above outputs a single image in a low-temperature and low-humidity environment (15 ° C./10% RH) to stop the rotation of the electrophotographic image forming apparatus. Thereafter, the image forming operation was resumed. The above operation was repeated (E character 1% printed image was intermittently endured), and an image output endurance test for 1000 sheets was performed. Similarly, the evaluation condition is that the electrophotographic photosensitive drum having a diameter of 24 mm is abutted by a pressing force by a spring of 4.9 N (0.5 kg weight) at one end and a total of 9.8 N (1 kg weight) at both ends, and is applied to the charging member. Was evaluated for durability by applying -1000 V only to the DC voltage. The toner used was a polymerized toner having an average particle diameter of 5.0 μm, and the electrophotographic photosensitive drum was a photosensitive drum mounted on a monochrome (black) cartridge of a trade name: “HP Color LaserJet 3000” (manufactured by Hewlett-Packard). . During the durability test, the process speed was set to 250 mm / s, a halftone image was used, and the output image was evaluated for an image defect due to dirt according to the following rank criteria.
Rank A: Not generated Rank B: Minor generation of streak-like or spot-like images at the end Rank C: Some streaky-like or potty-like images are generated, but there is no problem in actual use Rank D: Streaks The image quality is inferior in several places, and the image quality is inferior. Rank E: The image in the form of streaks and in the shape of a spot appears in the entire image, and the image quality is greatly inferior. As a result, as shown in Table 2. In addition, streaky and spotty images are partially generated, but the level is not problematic in practical use.

(Example 2)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, streak-like and potty-like images were partially generated in the contamination resistance evaluation and the discharge evaluation, but the level was not problematic in practical use.

(Example 3)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, in the stain resistance evaluation, a slight streak-like or potty-like image is generated at the end, and in the discharge evaluation, a streak-like or potty-like image is partially generated. However, there was no problem in practical use.

Example 4
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, in the stain resistance evaluation, a slight streak-like or potty-like image is generated at the end, and in the discharge evaluation, a streak-like or potty-like image is partially generated. However, there was no problem in practical use.

(Example 5)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, a slight streak-like or potty-like image was partially generated at the end in the stain resistance evaluation and discharge evaluation, but a good image was obtained.

(Example 6)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, no streak-like or spot-like image defects have occurred in the stain resistance evaluation, and a slight stripe-like or spot-like image has partially occurred at the end in the discharge evaluation. However, a good image was obtained.

(Example 7)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, no streak-like or spot-like image defects have occurred in the stain resistance evaluation, and a slight stripe-like or spot-like image has partially occurred at the end in the discharge evaluation. However, a good image was obtained.

(Example 8)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, no streak-like or defective image defects occurred in the stain resistance evaluation and the discharge evaluation, and a good image was obtained.

(Comparative Example 1)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, there was no problem in the stain resistance evaluation although streaky and spotty images were partially generated. However, in discharge evaluation, streak-like and spot-like images were generated on the entire image, and the image quality was greatly inferior.

(Comparative Example 2)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, streak-like and spotty images were generated in several places in the stain resistance evaluation, and streaky and potty-like images were generated in the entire image in discharge evaluation. The image quality was greatly inferior.

(Comparative Example 3)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, there was no problem in the stain resistance evaluation although streaky or spot-like images were slightly generated at the edges. However, in discharge evaluation, streak-like and spot-like images were generated on the entire image, and the image quality was greatly inferior.

(Comparative Example 4)
The charging member was evaluated in the same manner as in Example 1 except that the type of coarse particles and the number of parts by mass added were changed as shown in Table 1. As a result, as shown in Table 2, in the stain resistance evaluation and the discharge evaluation, several streaky and spotty images were generated, and the image quality was inferior.

It is a figure which shows the shape of the surface of the charging member of this invention. It is a figure which shows sectional drawing of the roller-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the roller-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the roller-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the roller-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the plate-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the plate-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the belt-shaped charging member of an example of the charging member of this invention. It is a figure which shows sectional drawing of the belt-shaped charging member of an example of the charging member of this invention. 1 is a schematic configuration diagram of an example of an electrophotographic image forming apparatus of the present invention. It is a figure which shows schematic structure figure of an example of the electrophotographic photoreceptor of this invention. It is a figure which shows schematic structure figure of an example of the electrophotographic photoreceptor of this invention.

Explanation of symbols

a, a1, a2 Conductive supports b, b1, b2 Conductive elastic layers c, c1, c2 Surface layer d Resistance layer e Second resistance layer P Transfer material RP Roughening particle 151 Photoconductor 153 Charging member (charging) roller)
154 Exposure equipment (laser beam scanner)
154L Exposure light 155 Developing device 155a Developing member 155b Stirring member 155c Toner regulating member 156 Transfer member (transfer roller)
S1 power supply S2 power supply

Claims (7)

  A charging member for contact charging, comprising a conductive support and a surface layer containing a binder resin and a conductive agent, and having conductivity imparted by the conductive agent, wherein the surface layer is further contained in the binder resin. The roughened particles are dispersed, the roughened particles contain a layered compound selected from boron nitride, silicon nitride, molybdenum disulfide and tungsten disulfide, and have an average particle diameter of 1 μm to 30 μm, The layer has a convex portion derived from the inclusion of the roughening particles on the surface, and the charging member has a surface roughness Rzjis of 3 μm or more and 20 μm or less.   2. The charging member according to claim 1, wherein the convex portion of the surface layer derived from the inclusion of the roughening particles generates a gap in a nip portion with the member to be charged.   2. The rough particle is a composite particle obtained by coating the surface of a mother particle with a child particle selected from the layered compound, and the mother particle is composed of a resin particle or an inorganic particle. Or the charging member of 2.   It is a charging member having a surface layer formed by dispersing the rough particles and the conductive agent in at least a binder resin on a conductive support, and the surface layer is obtained by adding the rough particles and the conductive agent. The charging member according to claim 1, wherein the charging member is a coating film formed by applying a paint.   5. A process cartridge comprising at least a charging member according to claim 1 and a member to be charged, which are integrated with each other and detachable from an electrophotographic image forming apparatus main body.   An electrophotographic image forming apparatus comprising at least the process cartridge according to claim 5, an exposure unit, and a transfer unit.   The electrophotographic image forming apparatus according to claim 6, wherein only the direct current voltage is applied to the charging member to charge the member to be charged.

Images