JP2007187900A - Conductive roller for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller capable of restraining the change of characteristic, even if it is left under severe environment over a long term, and to provide a process cartridge and an electrophotographic device. <P>SOLUTION: In the conductive roller 3 used in the electrophotographic device, the relation between the outside diameter D1, the micro hardness H1 and the resistance value R1 of the roller obtained, after it has been left standing under an environment of 40°C×95%RH for 300 hours and the outside diameter D0, the micro hardness H0 and the resistance value R0 of the roller obtained, before it is left standing under the environment, satisfy all of the expressions: 0.8D0≤D1≤1.2D0, 0.5H0≤H1≤1.5H0 and 0.1R0≤R1≤10R0. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive roller, a process cartridge having the conductive roller, and an electrophotographic apparatus.

  An image forming apparatus that employs an electrophotographic system, that is, an electrophotographic apparatus generally includes an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and a transferring unit.

  Further, as this charging means, a voltage (a voltage of only a DC voltage or a voltage in which an AC voltage is superimposed on a DC voltage) is applied to a charging member that is in contact with or close to the surface of the electrophotographic photosensitive member. Many systems that charge the surface of the photoreceptor are used.

  As a voltage to be applied to the charging member, when a voltage obtained by superimposing an AC voltage on a DC voltage is used, an AC power source is required, leading to an increase in size and cost of the electrophotographic apparatus, an increase in power consumption, From the above viewpoint, the voltage applied to the charging member may be only a DC voltage because the durability of the charging member and the electrophotographic photosensitive member may be reduced due to a large amount of ozone generated due to the use of an alternating current. preferable.

  Furthermore, a contact-type charging method is preferably used from the viewpoint of stably charging, reducing the generation of ozone, or reducing the cost.

  In the case of the contact-type charging method, the conductive roller as the charging member is disposed so as to be brought into contact with the electrophotographic photosensitive member by a pressing force such as a spring and to be driven to rotate. In many cases, the contact force between the conductive roller and the member to be charged is fixed.

  The electrophotographic apparatus and a product such as a so-called cartridge containing the central portion of the electrophotographic apparatus may be left for a long period of several weeks to several years until they are first used by a user. Further, when the user does not use the electrophotographic apparatus, naturally, the user may be left for a long time. These periods and the environment in which the cartridge is being transported are difficult to predict and, of course, may be exposed to high temperatures and high humidity for long periods. Usually, the configuration of the conductive roller as the charging member is generally composed of an elastic body made of rubber or elastomer and a surface layer made of a single layer or multiple layers. When left in such a high temperature and high humidity environment for a long time, the roller outer diameter may change greatly, the hardness may change, or the electrical resistance value may change greatly due to the influence of moisture and temperature. .

  For example, a change in roller resistance value or hardness prevents proper charging of the photosensitive member, resulting in an image defect. In the case of the contact charging method, since the roller is normally pressed against the photoconductor by a spring, the change in the outer diameter of the roller becomes a change in the pressing force, and the proper nip with respect to the photoconductor cannot be maintained, which causes image defects. There is a problem such as. Further, in a rubber elastic body usually used for a charging member, a change in outer diameter also causes a decrease in mechanical strength.

  In recent years, demands for higher speed, higher image quality, and higher durability for electrophotographic apparatuses are increasing. Such a trend is none other than the fact that even a slight change in outer diameter, change in hardness, or change in resistance value has become unacceptable.

  Nevertheless, conventionally, there has been no proposal to control the change in physical property value of the conductive roller as a charging member within a certain range when exposed to a harsh environment.

As another conventional example, Patent Document 1 can be cited.
Japanese Patent Laid-Open No. 2003-107853

  An object of the present invention is to provide a conductive roller, a process cartridge, and an electrophotographic apparatus that hardly change in characteristics even when left in a harsh environment for a long period of time.

The conductive roller according to one embodiment of the present invention,
This is a conductive roller used in electrophotographic equipment. Roller outer diameter (D1), micro hardness (H1), resistance value (R1) and resistance value (R1) after standing for 300 hours in an environment of 40 ° C x 95% RH The electrophotographic conductive roller is characterized in that the relationship among the roller outer diameter (D0), micro hardness (H0), and resistance value (R0) of the roller satisfies all the following ranges.

0.8D0 ≦ D1 ≦ 1.2D0
0.5H0 ≦ H1 ≦ 1.5H0
0.1R0 ≦ R1 ≦ 10R0

  According to the present invention, there is little change in characteristics even when left in a harsh environment for a long time, and as a result, an electrophotographic conductive roller capable of stably outputting a good image over a long period of time, and such a conductive roller. A process cartridge having an adhesive roller and an electrophotographic apparatus can be provided.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  As a result of intensive studies on the above problems, the present inventors have suppressed characteristic changes within a certain range even when left in a harsh environment for a long period of time, and can stably obtain a good image over a long period of time. The present inventors have found a conductive roller that can be used to arrive at the present invention.

  In the present invention, three different physical property values are defined, but these physical property values are very important as a conductive roller as a charging member, and if any one of them is out of the scope of the present invention, The effects of the invention cannot be expressed. Only when the three physical property values satisfy the scope of the present invention can the effects of the present invention be exhibited.

  For example, if the change in micro hardness of the roller after leaving it in a harsh environment (40 ° C x 95% RH) falls outside the range of the present invention and becomes low (soft) (when H1 <0.5H0), the contact nip When it becomes wider and conversely higher (harder) (when H1> 1.5H0), the contact nip becomes narrower. Therefore, it becomes difficult to maintain a proper contact nip, and charging becomes unstable, resulting in an image defect.

  Also, if the change in the roller resistance value after leaving in a harsh environment falls outside the scope of the present invention (when R1 <0.1R0), the resistance of the entire conductive roller as the charging member becomes too small. Therefore, it is difficult to prevent leakage due to pinholes, scratches, or the like on the surface of the electrophotographic photosensitive member that is a charged body. On the other hand, if the change in roller resistance value after leaving in a harsh environment is outside the range of the present invention (when R1> 10R0), the charging ability of the conductive roller as the charging member will be reduced, resulting in poor image quality. This causes a bad effect that it is easily noticeable.

  In addition, when the change in the outer diameter of the roller after leaving it in a harsh environment is out of the range of the present invention (D1> 1.2D0), the pressing force against the photoconductor becomes too strong, and an appropriate charging ability is obtained. Not only is this not possible, but the compression set becomes large, causing image defects as so-called set marks. On the other hand, when it is smaller than the scope of the present invention (when D1 <0.8D0), the pressing force on the photoconductor tends to be small, and the rotation with the photoconductor does not work well and is partially in the circumferential direction. Since a continuous energization portion is formed, an image defect is caused as a result. In addition, when the resistance is adjusted with the conductive particles, a large change in the outer diameter of the roller greatly changes the distance between the conductive particles, which may affect the conductivity.

  Although the conductive roller concerning this invention will not be restrict | limited especially if the range of this invention is satisfy | filled, As a preferable structure, it is a conductive roller which has one or more elastic layers on a support body.

  First, the support for the conductive roller only needs to have conductivity (conductive support). For example, a metal (alloy) support such as iron, copper, stainless steel, aluminum, or nickel is used. Can be used. In addition, for the purpose of imparting scratch resistance to these surfaces, plating treatment or the like may be performed as long as the conductivity is not impaired.

  As the elastic layer, conventionally known materials having various configurations can be used. For example, resin, rubber (natural rubber (which may be vulcanized) or synthetic rubber), thermoplastic elastomer, etc. And the like using an elastomer such as a binder as a binding material.

  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). Is mentioned.

  Synthetic rubbers 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.

  Thermoplastic elastomers include polyolefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene Examples thereof include a vinyl acetate thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, and a chlorinated polyethylene thermoplastic elastomer.

  These may be used alone or in combination of two or more as a mixture or copolymer.

  As the elastic layer, it is preferable to use an elastomer such as the above-described rubber or thermoplastic elastomer. Among them, rubber, particularly synthetic rubber, is used from the viewpoint of securing a sufficient nip between the charging roller and the electrophotographic photosensitive member. It is more preferable.

  Among the synthetic rubbers, polar rubber is preferably used from the viewpoint of uniform resistance and satisfying the scope of the present invention. Examples of the polar rubber include NBR and epichlorohydrin rubber. In particular, it can be said that it is more preferable to use a rubber component mainly composed of epichlorohydrin rubber in the sense that resistance control and hardness control of the elastic layer can be easily performed.

  Regarding epichlorohydrin rubber, 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) or ECO (ethylene oxide-epichlorohydrin copolymer) is used as EO. It is known to control the volume resistivity by changing the copolymerization ratio.

  In order to realize the present invention, the ethylene oxide content of the epichlorohydrin rubber is preferably 55 to 85 mol%. If it is less than 55 mol%, the volume resistance value becomes high. On the other hand, if it exceeds 85 mol%, not only will it be difficult to suppress various physical property values within the scope of the present invention, but also the problem that the polymer will be easily crystallized and the electrical resistance value will be higher. It will occur.

In the present invention, the volume resistivity of the elastic layer is preferably 10 ² to 10 ⁷ Ω · cm under a 23 ° C./50% RH environment. When the volume resistivity of the elastic layer is larger than 10 ⁷ Ω · cm, the charging ability of the conductive roller as the charging member is lowered, and an adverse effect that the image defect is easily noticeable occurs. On the other hand, the volume resistivity of the elastic layer is less than 10 ² Ω · cm, will be conductive roller total resistance becomes too small as a charging member, Ya pinholes on the surface of the electrophotographic photosensitive member, the member to be charged It becomes difficult to prevent leakage due to scratches or the like.

  The conductivity (volume resistivity) of the elastic layer can be adjusted by adding a conductive substance to the binder material. Examples include carbon-based materials such as carbon black, carbon fiber, graphite, and carbon nanotubes, metal-based materials such as metal flakes, metal powders, and metal fibers, conductive metal oxides such as tin oxide, zinc oxide, and titanium oxide, and Examples thereof include alkali metal salts and ammonium salts.

  When using an epichlorohydrin rubber component, it is particularly preferable to use an ammonium salt. However, when an epichlorohydrin rubber component is used, care must be taken because the volume resistivity greatly depends on the amount of ethylene oxide as described above.

  As a method of providing the elastic layer on the support, an elastic material may be prepared in advance by tube extrusion, and then inserted into the support, or may be in close contact with the support while extruding the elastic material (for example, cloth The head extrusion method may be used.

  Further, as the shape of the elastic layer, from the viewpoint of improving the uniform adhesion between the charging roller and the electrophotographic photosensitive member, the central portion in the longitudinal direction is the thickest, and the so-called shape becomes narrower toward both ends in the longitudinal direction, so-called It is preferable to form in a crown shape. In general, the charging roller is brought into contact with the electrophotographic photosensitive member by applying a predetermined pressing force to both end portions of the support, and the pressing force is small in the central portion in the longitudinal direction, and becomes closer to both end portions in the longitudinal direction. Therefore, the density unevenness may occur between the image corresponding to the central portion and the images corresponding to both end portions. The crown shape is formed to prevent this. The crown amount is preferably 30 to 200 μm in the difference in outer diameter between the central portion and a position 90 mm away from the central portion. If it is smaller than 30 μm, a state in which the end portion comes into contact and the center portion does not come into contact easily occurs. If it is larger than 200 μm, conversely, the center part comes into contact but the end part does not come into contact easily.

  Further, an additive (softening oil, plasticizer, etc.) and various fine particles may be added to the elastic layer in order to adjust hardness and the like. The elastic layer may be the outermost surface layer of the conductive roller as a charging member, but when an additive such as softening oil or plasticizer is used for the elastic layer as described above, the additive is added to the surface of the conductive roller. From the viewpoint of preventing bleed out, this elastic layer is preferably not the outermost surface layer of the conductive roller.

  As described above, when an additive is used in the elastic layer, one or two layers are further provided on the elastic layer from the viewpoint of enhancing the prevention of bleeding out of the additive and preventing contamination of the electrophotographic photosensitive member and other members. You may provide the surface layer more than a layer. What is necessary is just to select suitably as a material which comprises a surface layer according to the characteristic required. Examples include thermoplastic resins and thermosetting resins. Examples of the thermoplastic resin include polyamide resin, polyolefin resin, (meth) acrylic resin, styrene resin, polyester resin, and fluorine resin. Examples of the thermosetting resin include a polyimide resin, a phenol resin, a silicone resin, an epoxy resin, and a polyurethane resin. Among them, in the present invention, a polyurethane resin is preferably used from the viewpoint of ozone resistance and durability.

The volume resistivity of the surface layer in the present invention is preferably 10 ¹⁶ Ω · cm or less in a 23 ° C./50% RH environment, and is preferably larger than the volume resistivity of the elastic layer. If the volume resistivity of the surface layer is too large, the charging ability as a conductive roller as a charging member will be reduced, and the bad effect that image defects will be more conspicuous, and the ability to uniformly charge (charging uniformity) will be reduced. This will cause a negative effect. On the other hand, if the volume resistivity of the surface layer is smaller than the volume resistivity of the elastic layer, it is difficult to prevent leakage due to pinholes, scratches, or the like on the surface of the electrophotographic photosensitive member that is the object to be charged. Thus, in order to adjust the volume resistivity of the surface layer, the surface layer may contain one type or two or more types of conductive substances. As the conductive material, any material may be used as long as the characteristic value of the conductive roller can be suppressed within the range of the present invention.

  In general, carbon black is well known as a substance that develops conductivity. According to the study by the present inventors, it was difficult to control the physical property values within the scope of the present invention when the resistance was adjusted only with carbon black. As a result of further studies on such problems, the present inventors have been able to solve the problem by including the composite particles shown below in the surface layer.

  The composite particles have a shape in which carbon black is roughly coated on the central particles. The average particle size of the composite particles is preferably 1 to 1000 nm. More preferably, it is 5-500 nm. If it is this range, the reinforcement effect of the surface layer in the structure mentioned above will fully be exhibited. Further, it is easy to control dispersibility with respect to the surface layer by agglomeration of the composite particles.

  The composite particle shape may be any shape such as spherical shape, granular shape, polyhedron shape, needle shape, spindle shape, rice grain shape, flake shape, scale shape, and plate shape, but in order to further improve the effects of the present invention. Is preferably spherical or granular.

  The center (core) particles of the composite particles are metal oxides or composite metal oxide fine particles. Specifically, zinc oxide, tin oxide, indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.), iron oxide And silica, alumina, magnesium oxide, zirconium oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate, and calcium zirconate. More preferred are silica, alumina, titanium oxide, zinc oxide, magnesium oxide, iron oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate, and calcium zirconate.

  The shape of the composite particle greatly depends on the particle size and shape of the center particle. Therefore, the average particle diameter of the center particles is preferably 1 to 1000 nm. More preferably, it is 5-500 nm.

  The shape of the center particle may be any shape such as spherical shape, granular shape, polyhedron shape, needle shape, spindle shape, rice grain shape, flake shape, scale shape, and plate shape, but the effect of the present invention is further improved. For this purpose, spherical or granular is preferred.

  Carbon black coated on the center particle is preferably furnace black, ketjen black, channel black, or the like.

  These may be used alone or in combination of two or more.

  The center particle is preferably surface-treated. Thereby, the center particle surface and carbon black can be adhered more firmly. Accordingly, when the composite particles are dispersed in rubber, resin, elastomer, etc., carbon black can be prevented from being detached, and the effects of the present invention can be further exhibited.

  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. More preferred are organosilicon compounds such as alkoxysilanes and polysiloxanes, and various coupling agents such as silane, titanate, aluminate and zirconate, and more preferred are organosilicon compounds.

  Examples of the organosilicon compound include alkoxysilanes represented by formula (1), organosilane compounds produced from alkoxysilanes, polysiloxanes represented by formula (2), modified polysiloxanes represented by formula (3), and formulas (4) And a terminally modified polysiloxane represented by formula (5) and a fluoroalkylsilane represented by formula (5) or a mixture thereof.

アルコキシシランとしては、具体的には、メチルトリエトキシシラン、ジメチルジエトキシシラン、フェニルトリエトキシシラン、ジフェニルジエトキシシラン、ジメチルジメトキシシラン、メチルトリメトキシシラン、フェニルトリメトキシシラン、ジフェニルジメトキシシラン、イソブチルトリメトキシシラン及びデシルトリメトキシシラン等が挙げられる。

Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane. Examples include methoxysilane and decyltrimethoxysilane.

  Considering the adhesion strength of carbon black to the center particle, alkoxysilanes such as methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, phenyltriethoxysilane, etc. It can be said that a silane compound is more preferable.

また、ポリシロキサンとしては、メチルハイドロジェンシロキサン単位を有するポリシロキサン、ポリエーテル変成ポリシロキサン及び末端がカルボン酸で変成された末端カルボン酸変成ポリシロキサンを挙げることができる。

Examples of the polysiloxane include a polysiloxane having a methylhydrogensiloxane unit, a polyether-modified polysiloxane, and a terminal carboxylic acid-modified polysiloxane having a terminal modified with a carboxylic acid.

  Specific examples of the fluoroalkylsilane include trifluoropropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecylmethyldimethoxysilane, trifluoropropylethoxysilane, Examples thereof include decafluorooctyltriethoxysilane and heptadecafluorodecyltriethoxysilane.

カップリング剤のうち、シラン系カップリング剤としては、ビニルトリメトキシシラン、ビニルトリエトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、Ｎ−β（アミノエチル）−γ−アミノプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジメトキシシラン及びγ−クロロプロピルトリメトキシシラン等が挙げられる。

Among coupling agents, silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, Examples include γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-chloropropyltrimethoxysilane.

  Examples of titanate coupling agents include isopropyl tristearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, tetraoctyl bis (ditridecyl phosphate) titanate, tetra (2- Examples include 2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, and bis (dioctylpyrophosphate) ethylene titanate.

  Examples of the aluminate coupling agent include acetoalkoxy aluminum diisopropylate, aluminum diisopropoxy monoethyl acetoacetate, aluminum trisethyl acetoacetate, and aluminum trisacetylacetonate.

  Examples of the zirconate coupling agent include zirconium tetrakisacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium tributoxymonoethylacetoacetate, zirconium tributoxyacetylacetonate, and the like.

  The oligomer preferably has a molecular weight of 300 or more and less than 10,000, and the polymer compound preferably has a molecular weight of about 10,000 or more and about 100,000. In view of uniform coating treatment on the center particles, oligomers or polymer compounds that are liquid or soluble in water or various solvents are preferable.

  The coating amount of the surface treatment agent is preferably 0.01 to 15.0% by mass with respect to the center particle. If it is less than 0.01% by mass, it may be difficult to adhere carbon black to the center particles. If the amount is 15.0% by mass, the carbon black can be sufficiently firmly attached to the center particle or a sufficient amount can be adhered, so that it is meaningless to coat more than necessary. More preferably, it is 0.02-12.5 mass%, Most preferably, it is 0.03-10.0 mass%.

The volume resistance value of the composite particles of the present invention can be arbitrarily controlled between the volume resistance value of carbon black used for adhesion and the volume resistance value of the center particles. Specifically, it is 1.0 × 10 to 1.0 × 10 ⁸ Ω · cm, preferably 5.0 × 10 to 5.0 × 10 ⁷ Ω · cm.

  The amount of carbon black attached is 1 to 500 parts by mass with respect to 100 parts by mass of the center particles. If it is less than 1 part by mass, it is difficult to reduce the electrical resistance of the resulting composite particles. If it exceeds 500 parts by mass, the effect of reducing electrical resistance is sufficiently obtained, so there is no point in adhering more than necessary beyond 500 parts by mass.

  The composite particles can be obtained by mixing the center particles and carbon black. When surface-treating the center particles, the center particles can be surface-treated first, and then the surface-treated center particles and carbon black are mixed.

  The surface treatment on the center particle is performed by mechanically mixing and stirring the center particle and the surface treatment agent or the solution of the surface treatment agent, or spraying the surface treatment agent or the solution of the surface treatment agent on the center particle. And mixing and stirring.

  In addition, when alkoxysilane or fluoroalkylsilane is used as the surface treatment agent, the coated alkoxysilane or fluoroalkylsilane is partly produced through a coating process, an organosilane compound produced from alkoxysilane or You may coat | cover as a fluorine-containing organosilane compound produced | generated from fluoroalkylsilane. Even in this case, the subsequent adhesion of carbon black is not affected.

  In order to uniformly coat the surface of the center particle with the surface treatment agent, it is preferable that the agglomeration of the center particles is unraveled in advance using a pulverizer.

  As an apparatus for mixing and stirring the center particle and carbon black, the surface-treated center particle and carbon black, the center particle and the surface treatment agent, an apparatus capable of applying a shearing force to the powder layer is preferable. In particular, a device capable of simultaneously performing shearing, spatula and compression, for example, a wheel-type kneader, a ball-type kneader, a blade-type kneader, or a roll-type kneader can be used, and the wheel-type kneader is more effective. Can be used for Further, after mixing and stirring, drying or heat treatment may be further performed as necessary.

  Furthermore, regarding the surface treatment of the center particles, there can be mentioned a method in which the center particles and the surface treatment agent are mixed and dispersed in an appropriate solvent, and the treatment agent is adhered to the particle surface. As a dispersion means, conventionally known solution dispersion means such as a ball mill, a sand mill, a paint shaker, a dyno mill and a pearl mill can be used. Next, the solvent is removed from the dispersion solution, and the surface treatment agent is fixed to the particle surface. Moreover, you may heat-process further after this as needed. Further, a catalyst for promoting the reaction can be added to the mixed solution. Furthermore, you may further grind | pulverize the particle | grains after surface treatment as needed.

  The center particle may have a fine particle surface previously coated with an intermediate coating comprising at least one selected from aluminum hydroxide, aluminum oxide, silicon hydroxide, and silicon oxide. This is because there are cases where the adhesion between the center particle surface and the carbon black can be strengthened.

  The coverage by the intermediate coating is preferably 0.01 to 20% by mass. If it is less than 0.01% by mass, the effect of improving the adhesion of carbon black may not be obtained. If it exceeds 20% by mass, no further effect of improving adhesion can be obtained, so there is no point in covering more than necessary.

  In the present invention, it is preferable to add metal oxide or composite metal oxide fine particles in addition to the conductive composite particles to the surface layer. It is clear from the study by the present inventors that when the metal oxide or composite metal oxide fine particles are present in the surface layer, there is little change in physical properties when left in a high temperature and high humidity environment. The reason is not clear, but it is presumed that the reinforcing effect of the binder resin is exhibited and the physical properties are stabilized.

  Specific examples of the metal oxide or composite metal oxide fine particles suitably used in the present invention include zinc oxide, tin oxide, indium oxide, titanium oxide (titanium dioxide, titanium monoxide, etc.), iron oxide, silica, Alumina, magnesium oxide, zirconium oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate, calcium zirconate and the like can be mentioned. More preferred are silica, alumina, titanium oxide, zinc oxide, magnesium oxide, iron oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate, and calcium zirconate.

  The average particle diameter of the metal oxide or composite metal oxide fine particles is preferably 1 nm to 1000 nm. More preferably, it is 5-500 nm. By setting it within this range, the effects of the present invention can be sufficiently exerted, and aggregation of fine particles can be suppressed, and the dispersibility of the binder in the surface layer can be well controlled.

  The metal oxide or composite metal oxide fine particles are preferably surface-treated. Examples of the surface treatment include surface treatment with a fatty acid and a fatty acid metal salt in addition to the same surface treatment method as that for the composite particles described above.

  As the fatty acid, a saturated or unsaturated fatty acid can be used, and those having 12 to 22 carbon atoms are preferable. As the fatty acid metal salt, a salt of a saturated or unsaturated fatty acid and a metal can be used, and a fatty acid having 12 to 18 carbon atoms and an alkaline earth metal such as magnesium, calcium, strontium and barium, lithium, sodium, potassium And salts with alkali metals such as zinc, aluminum, copper, iron, lead, tin and the like.

  Among these, the surface treatment of the metal oxide in the present invention is particularly preferably a surface treatment with an organosilicon compound such as alkoxysilane or polysiloxane. This is because these compounds have good adhesion to the surface of the metal oxide fine particles and at the same time have the effect of further improving the dispersibility of the metal oxide fine particles in rubber, resin, elastomer and the like. Further, by using a compound similar to the surface treatment used for the composite particles, it is possible to more easily control the dispersion such that another metal oxide fine particle exists between the composite particles.

  The coating amount of the surface treatment agent is preferably 0.01 to 15.0% by mass. Within this range, sufficient dispersibility can be imparted to the metal oxide fine particles. More preferably, it is 0.02-12.5 mass%, Most preferably, it is 0.03-10.0 mass%.

  The surface treatment method for the metal oxide fine particles can be performed by the same method as for the composite particles.

  Among these, the surface treatment method for the metal oxide fine particles is particularly preferably the above-described mixing and dispersion method in a solution. According to this method, it becomes possible to perform the surface treatment firmly and uniformly on the surface of the metal oxide fine particles, the dispersibility of the metal oxide fine particles can be greatly improved, and the effects of the present invention are sufficiently obtained. It can be pulled out.

  Furthermore, in the present invention, in addition to the composite particles and metal oxide fine particles, other fine particles can be contained to such an extent that the effects of the present invention are not impaired.

The fine particles contained in the surface layer are roughly classified into conductive fine particles and insulating fine particles. In the present invention, “conductive fine particles” means particles having a volume resistivity of 1 × 10 ⁸ Ω · cm or less, and “insulating fine particles” have a volume resistivity of 1 × 10 10 as described above. ^It means particles exceeding ⁸ Ω · cm.

  Examples of the conductive fine particles include particles of carbon black, tin oxide, titanium oxide, zinc oxide, barium sulfate, copper, aluminum, nickel, and the like.

  Insulating fine particles include fine particles of polymer compounds such as polyamide resin, silicone resin, fluororesin, (meth) acrylic resin, styrene resin, phenol resin, polyester resin, melamine resin, urethane resin, olefin resin, epoxy resin, And resin particles such as copolymers, modified products and derivatives thereof, 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), epichlorohydrin rubber, etc., polyolefin thermoplastic elastomer, urethane thermoplastic elastomer, polystyrene thermoplastic elastomer, fluorine rubber Thermoplastic elastomers such as thermoplastic thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, polybutadiene thermoplastic elastomer, ethylene vinyl acetate thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, and chlorinated polyethylene thermoplastic elastomer An elastomer fine particle is mentioned.

Other insulating fine particles include barium sulfate, molybdenum disulfide, calcium carbonate, magnesium carbonate, dolomite, talc, kaolin clay, mica, aluminum hydroxide, magnesium hydroxide, zeolite, wollastonite, diatomaceous earth, Examples thereof include particles such as glass beads, bentonite, montmorillonite, asbestos, hollow glass spheres, graphite, rice husk, organometallic compounds, and organometallic salts. Further, iron oxides such as ferrite, magnetite, and hematite, activated carbon, and the like can also be used. Examples of the ferrite include ferrite described in “Electronic Material Series Ferrite” (Maruzen Co., Ltd., issued on October 10, 1997, 5th printing), and specifically, MnFe ₂ O ₄ , FeFe ₂ O ₄ , ZnFe ₂ O ₄ , MgFe ₂ O _4, γ-Fe ₂ O _{4 and the} like. Examples of the activated carbon include activated carbon described in “New Edition Activated Carbon-Fundamentals and Applications” (Kodansha Co., Ltd., issued on October 20, 1992, 2nd printing). Examples thereof include activated carbon, coconut shell activated carbon, and coal activated carbon.

  These particles may be used alone or in combination of two or more thereof, and may be those subjected to surface treatment, modification, introduction of functional groups or molecular chains, coating, and the like. From the viewpoint of controlling the dispersibility of the particles, the particles are preferably subjected to a surface treatment. As the surface treatment, the same surface treatment method as that used for the surface treatment of the composite particles can be used.

  The surface layer may contain a release agent in order to improve the release property of the surface of the conductive roller as the charging member. By including a release agent in the surface layer, dirt adhesion on the surface of the conductive roller can be reduced, so that the durability of the conductive roller is improved, and between the conductive roller and the electrophotographic photoreceptor. Relative movement between them becomes smooth, reducing the occurrence of irregular movement states such as stick-slip, resulting in irregular wear on the surface of the conductive roller as a charging member, abnormal noise, etc. Can be improved. In addition, when the mold release agent contained in a surface layer is a liquid, it acts also as a leveling agent when forming a surface layer.

  Many release agents use low surface energy and those using slidability, and their properties are liquid or solid. Examples of the solid and slidable material (solid lubricant) include, for example, the substances described in the Solid Lubrication Handbook (Publisher; Koshobo Co., Ltd., published on March 15, 1982), specifically Metal oxides such as graphite, graphite fluoride, molybdenum disulfide, tungsten disulfide, boron nitride, and lead monoxide can be used.

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

  In addition to the various materials described above, the surface layer and the elastic layer can appropriately contain materials having various functions. Examples of such materials include anti-aging agents such as 2-mercaptobenzimidazole, lubricants such as stearic acid and zinc stearate, antioxidants, pigment dispersants, fillers, and flame retardants.

  Moreover, you may surface-treat to each surface of said surface layer and an elastic layer. Examples of the surface treatment include a surface processing treatment using UV or electron beam, and a surface modification treatment for attaching and / or impregnating a compound or the like on the surface.

  The surface layer may be formed by, for example, adhering or covering a sheet-shaped or tube-shaped layer formed in advance to a predetermined film thickness on a support, electrostatic spray coating or dipping. You may carry out by application | coating methods, such as application | coating. Moreover, after forming a layer roughly by extrusion molding, the method of adjusting the shape of a layer by grinding | polishing etc. may be used, and the method of hardening and shape | molding material in a predetermined shape within a metal mold | die may be sufficient.

  When the surface layer is formed by a coating method, the solvent used in the coating solution may be any solvent that can dissolve the binder material, for example, alcohols such as methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, and the like. , Ketones such as 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, and acetic acid Esters such as methyl and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, ethylene chloride, dichloroethylene, carbon tetrachloride and trichloroethylene, benzene, toluene, xylene, ligroin, chlorobenzene and dichlorobenzene Aromatic compounds such as Zen like.

  As a method of dispersing the fine particles in the surface layer material, the surface layer material and the fine particles are mixed with a ribbon blender, a Nauter mixer, a Henschel mixer, a super mixer, or the like, or mixed with a Banbury mixer, a pressure kneader, or the like. Existing methods can be used.

  When the surface layer is formed by a coating method, a solvent, a surface layer material, and fine particles are mixed, and conventionally known solution dispersing means such as the ball mill, sand mill, paint shaker, dyno mill, and pearl mill described above can be used. .

  Here, the example of a layer structure of the electroconductive roller of this invention is shown in FIGS.

  The conductive roller shown in FIG. 3 is a roller-shaped charging member, and includes a support a, an elastic layer b formed on the support a, and a surface layer c formed on the elastic layer b. This is a two-layered conductive roller.

  The conductive roller shown in FIG. 4 is a roller-shaped charging member, and has a three-layer structure in which a second surface layer d is provided between the elastic layer b and the surface layer c of the conductive roller shown in FIG. Sex roller.

  The conductive roller shown in FIG. 5 is a roller-shaped charging member, and has four layers in which a third surface layer e is provided between the second surface layer d and the surface layer c of the conductive roller shown in FIG. It is an electroconductive roller of composition.

  In addition, although the thing of the structure which a surface layer consists of two or more is illustrated here, the structure which an elastic layer consists of two or more layers in this invention may be taken.

  FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photosensitive member and a conductive roller of the present invention.

  In FIG. 1, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven in a direction of an arrow about a shaft 2 at a predetermined peripheral speed.

  The surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by a charging member (roller-shaped charging member: charging roller in FIG. 1), and then subjected to slit exposure or laser beam. Exposure light (image exposure light) 4L output from exposure means (not shown) such as scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photosensitive member 1 is transferred from a transfer material supply unit (not shown) to the electrophotographic photosensitive member 1 and the transfer unit by a transfer bias from a transfer unit (transfer roller or the like) 6. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronism 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 surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 8 to receive the image fixing, and is printed out as an image formed product (print, copy). Is done.

  After the toner image is transferred, the surface of the electrophotographic photosensitive member 1 is cleaned by a cleaning means (cleaning blade or the like) 7 to remove the developer (toner) remaining after transfer, and then used repeatedly for image formation. . In addition, after the surface of the electrophotographic photosensitive member 1 is cleaned by the cleaning unit 7, the surface of the electrophotographic photosensitive member 1 may be neutralized by pre-exposure light before being charged by the charging member 3.

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

  The electrophotographic photosensitive member 1 includes, for example, an electrophotographic photosensitive member having a cylindrical support (conductive support) and a photosensitive layer containing an inorganic photosensitive material and / or an organic photosensitive material formed on the support. A body or the like can be employed. In addition, the electrophotographic photosensitive member 1 may further include a charge injection layer for charging the surface of the electrophotographic photosensitive member to a predetermined polarity and potential.

  Examples of the developing method employed by the developing unit 3 include a jumping developing method, a contact developing method, and a magnetic brush method. In the case of an electrophotographic apparatus that outputs a color image (full color image), the contact development method is particularly preferable for the purpose of improving toner scattering properties.

  Hereafter, the measuring method of the physical property parameter in this invention is shown.

(1) Micro hardness The micro hardness of the surface of the conductive roller in the present invention is measured in a peak hold mode in a 23 ° C./55% RH environment using a micro hardness meter MD-1 type (manufactured by Kobunshi Keiki Co., Ltd.). To do. In more detail, place the conductive roller on a metal plate, place a metal block, and fix it easily so that the conductive roller does not roll. Press the measuring terminal accurately and read the value after 5 seconds. A total of 9 points are measured at three positions in the circumferential direction of both ends and the center at a position of 30 to 40 mm from the rubber end of the conductive roller, and this average value is defined as micro hardness.

(2) Roller resistance The conductive roller 22 is left in an N / N environment (normal temperature and humidity: 23 ° C./55% RH) for 24 hours, and the cylindrical electrode (metal roller) 31, fixed resistor 32, recording shown in FIG. The resistance of the conductive roller is measured at an applied voltage of 200 V by a resistance value measuring device including a meter (recorder) 33 and the like.

(3) Roller outer diameter For measurement, a commercially available laser outer diameter measuring device is used, and the charging roller is rotated 45 ° at a time to perform a total of four phase measurements in the circumferential direction. This measurement is carried out at three points at the roller longitudinal center and 90 mm from the center, and the average of all 12 measured values is taken as the outer diameter of the conductive roller.

  In the meantime, although the description has been made mainly on the example in which the conductive roller of the present invention is used as a charging roller for an electrophotographic apparatus, this roller is not only a charging roller but also a developing roller used in an electrophotographic apparatus, It can also be suitably used as various functional rollers such as a transfer roller.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these.

Example 1
(1) Preparation of Composite Particles Silica fine particles (average particle size 14 nm, volume resistivity 2.6 × 10 ⁸ Ω · cm) 8.0 kg as a center particle of composite particles, 160 g of methyl hydrogen polysiloxane, edge runner Was added to the silica fine particles while being operated, and mixed and stirred for 30 minutes with a linear load of 588 N / cm (60 Kg / cm). The stirring speed at this time was 22 rpm.

Next, carbon black particles (particle size 22 nm, volume resistivity ^{2.0 × 10 2 Ω · cm)} 8.0kg, was added over 10 minutes while operating the edge runner, further 588N / cm (60Kg / cm The mixture was stirred for 60 minutes at a linear load of ()) to adhere carbon black to the methylhydrogenpolysiloxane coating, and then dried at 80 ° C. for 60 minutes using a dryer to obtain composite particles. The stirring speed at this time was 22 rpm.

The obtained composite particles had an average particle size of 18 nm and a volume resistivity of 1.8 × 10 ² Ω · cm.

(2) Preparation of surface-treated metal oxide fine particles 1 kg of rutile-type titanium oxide fine particles (average particle size 15 nm, volume resistivity 3.8 × 10 ¹⁰ Ω · cm), and 100 g of isobutyltrimethoxysilane as a surface treatment agent Then, 3000 g of toluene was mixed as a solvent to prepare a slurry.

  This slurry was mixed with a stirrer for 30 minutes, and then supplied to Viscomill in which 80% of the effective internal volume was filled with glass beads having an average particle diameter of 0.8 mm, and wet crushing was performed at a temperature of 20 ± 5 ° C. .

  The slurry obtained by the wet pulverization treatment was subjected to vacuum distillation using a kneader (bath temperature: 110 ° C., product temperature: 30 to 60 ° C., degree of vacuum: about 100 Torr), and surfaced at 120 ° C. for 2 hours. The treating agent was baked. The fine particles after the baking treatment were cooled to room temperature and then pulverized using a pin mill.

(Preparation of conductive roller)
A stainless steel core having a diameter of 6 mm and a length of 252.5 mm was used as a support (conductive support). A thermosetting adhesive (Metal Rock U-20, manufactured by Toyo Chemical Laboratories) was applied thereto and dried.

  Next, epichlorohydrin rubber terpolymer (ethylene oxide (EO) / epichlorohydrin (EP) / allyl glycidyl ether (AGE) = 73 mol% / 23 mol% / 4 mol%) 100 parts by mass, zinc oxide 2 types 5 parts by mass, 1 part by weight of stearic acid, 0.5 part by weight of 2-mercaptobenzimidazole (MB) (anti-aging agent), 45 parts by weight of calcium carbonate, 5 parts by weight of an aliphatic polyester plasticizer, a quaternary ammonium salt represented by the following formula 2 parts by mass,

及び、カーボンブラック（平均粒径：５０ｎｍ、体積抵抗率：０．１Ω・ｃｍ）５質量部を、５０℃に調節した密閉型ミキサーにて１０分間混練（Ａ練り）して、原料コンパウンドを調製した。

And, 5 parts by mass of carbon black (average particle size: 50 nm, volume resistivity: 0.1 Ω · cm) is kneaded (A kneading) for 10 minutes in a closed mixer adjusted to 50 ° C. to prepare a raw material compound. did.

  Into this raw material compound, 1% by mass of sulfur (vulcanizing agent), 1% by mass of dibenzothiazyl sulfide (DM) (vulcanization accelerator) and 1% by mass of tetra based on the above epichlorohydrin rubber terpolymer. Methyl thiuram monosulfide (TS) was added and kneaded (B kneading) for 10 minutes with a two-roll machine cooled to 20 ° C. to obtain an elastic layer compound.

  The elastic layer compound is extruded on an adhesive-coated support by an extrusion molding machine so as to form a roller shape having an outer diameter of about 13 mm, and then the temperature of the electric oven adjusted to 160 ° C. After vulcanization and curing of the adhesive for 1 hour, both ends of the rubber were cut off and the surface was polished so as to form a roller having an outer diameter of about 12 mm, and an elastic layer was formed on the support. Formed. At this time, the crown amount (difference in the outer diameter at a position 90 mm away from the central portion and the central portion) was 110 μm.

  Subsequently, methyl isobutyl ketone was added to a caprolactone-modified acrylic polyol solution (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd., Plaxel is a registered trademark), and the solid content was adjusted to 21% by mass.

Furthermore, with respect to 100 parts by mass of the caprolactone-modified acrylic polyol solution,
14 parts by mass of composite particles prepared in (1) 17.5 parts by mass of metal oxide fine particles prepared in (2) 0.166 parts by mass of modified dimethyl silicone oil (trade name; SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) )
7: 3 mixing of each butanone oxime block of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)
56.1 parts by mass were added to prepare a mixed solution.

  At this time, the mixture of HDI and IPDI was added so that “NCO / OH = 1.0”. For HDI and IPDI, HDI (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Kogyo. Duranate is a registered trademark) and IPDI (trade name: Bestanat B1370, manufactured by Degussa Huls) were used.

  In a 450 mL glass bottle, 250 g of the mixed solution and 200 g of glass beads having an average particle diameter of 0.8 mm as a medium were mixed and dispersed for 12 hours using a paint shaker disperser to obtain a dispersed solution.

Furthermore, 14 parts by mass of crosslinked polymethyl methacrylate (PMMA) particles (average particle size: 5.0 μm (5000 nm), volume resistivity: 1.0 × with respect to 100 parts by mass of the caprolactone-modified acrylic polyol solution was added to this dispersion solution. 10 ¹⁵ Ω · cm) was added, and the mixture was further dispersed for 1 hour, and separated from the glass beads by filtration to obtain a surface layer coating solution.

  This surface layer coating solution is dipped on the elastic layer once, air-dried at room temperature for 30 minutes or more, then dried in a hot air circulating dryer set at 80 ° C. for 1 hour, and hot air set at 160 ° C. It dried for 1 hour with the circulation dryer, and formed the surface layer on the elastic layer. The dipping coating pulling speed is adjusted so that the initial speed is 20 mm / s and the final speed is 2 mm / s, and the speed varies linearly with time between 20 mm / s and 2 mm / s. I let you.

  Thus, the electroconductive roller as a charging member which has an elastic layer and a surface layer (outermost layer) in this order on the support body was produced.

  The micro hardness, outer diameter, and resistance value of the conductive roller produced in this example were measured by the methods described above. After the measurement, the conductive roller is left in a 40 ° C./95% RH environment for 300 hours. After leaving it, it is taken out from the environment and left in a 23 ° C./50% RH environment for 24 hours. Thereafter, the micro hardness, outer diameter, and resistance value of the conductive roller were measured again. The results are shown in Table 1. All physical property values were within the scope of the present invention.

  Thereafter, the conductive roller left in a harsh environment is mounted on an electrophotographic apparatus having a configuration shown in FIG. 2 (a voltage of only DC voltage is applied to the conductive roller), and in a 23 ° C./50% RH environment, A halftone image was output and the output image was evaluated.

  It became clear from our examination that if the image is good under these conditions, a stable image can be obtained over a long period of time.

  Table 1 shows the evaluation results of the output image. In Table 1, ◎ is very good, ○ is good, and × is an image level in which image defects are conspicuous in a halftone image.

  The electrophotographic apparatus having the configuration shown in FIG. 2 will be described below.

  Reference numeral 151 denotes a cylindrical electrophotographic photosensitive member having a diameter of 30 mm in this embodiment. The electrophotographic photoreceptor 151 is rotationally driven at a predetermined process speed (188 mm / s) in the direction of the arrow.

  Reference numeral 153 denotes a conductive roller (charging roller) of this embodiment. S1 is a power source for applying only a DC voltage to the charging roller. The charging roller 153 is brought into contact (contact) with the electrophotographic photosensitive member 151 with a predetermined pressing force (spring pressure), and is driven to rotate in the forward direction with respect to the rotation of the electrophotographic photosensitive member 151 (0. 5 kg weight, and both ends are brought into contact with a pressing force of a total of 1 kg weight). The charging roller 153 is charged (contact charged) to the surface of the electrophotographic photosensitive member 151 at −400 V by applying a voltage of only DC voltage −1000 V from the power source S1.

  Reference numeral 154 denotes a laser beam scanner as exposure means. The surface of the electrophotographic photosensitive member 151 charged to −400 V (dark portion potential) by the charging roller 153 is irradiated with exposure (image exposure) light 154L corresponding to target image information by the laser beam scanner 154, so that the electron The potential of −400 V on the surface of the photographic photoreceptor is selectively attenuated to −150 V (bright part potential), and an electrostatic latent image is formed on the surface of the electrophotographic photoreceptor 151.

  Reference numeral 155 denotes a developing device (developing means). The developing device 155 includes a toner carrier 155a that is disposed in an opening of a developing container that accommodates toner (developer) and carries the toner, a stirring member 155b that stirs the contained toner, and a toner carrier. And a toner regulating member 155c that regulates the amount of toner 155a (toner layer thickness). The developing device 155 selectively attaches toner (negative toner) charged to −350 V (development bias) to the bright portion potential portion of the electrostatic latent image formed on the surface of the electrophotographic photoreceptor 151, The electrostatic latent image is visualized as a toner image. The toner carrier 155a is in contact with the electrophotographic photosensitive member, or in contact with the electrophotographic photosensitive member through the toner to be carried. That is, the contact development method is adopted. Therefore, the toner carrier 155a is a developing roller provided with an elastic layer (made of rubber) provided with conductivity on a conductive support from the viewpoint of ensuring contact stability (of course, the elastic layer has an elastic material). A foam may be used as the surface, or a separate layer may be provided on the elastic layer, surface treatment (surface modification using UV or electron beam, surface modification for attaching and / or impregnating a compound, etc. on the surface). Quality treatment etc.).

  Reference numeral 156 denotes a transfer roller as transfer means. The transfer roller 156 is a transfer roller formed by coating a conductive support with an elastic resin layer adjusted to a medium resistance. The transfer roller 156 is brought into contact with the electrophotographic photosensitive member 151 with a predetermined pressing force to form a transfer nip portion, and is approximately equal to the rotational peripheral speed of the electrophotographic photosensitive member 151 in the forward direction with the rotation of the electrophotographic photosensitive member 151. Rotates at the same peripheral speed. Further, a transfer voltage having a polarity opposite to the charging characteristics of the toner is applied from the power source S2. A transfer material P is fed to a transfer nip portion from a paper feeding mechanism (not shown) at a predetermined timing, and the back surface of the transfer material P is opposite to the charging polarity of the toner by a transfer roller 156 to which a transfer voltage is applied. By being charged to the polarity, the toner image on the surface of the electrophotographic photosensitive member 151 is electrostatically transferred to the surface of the transfer material P (the surface facing the electrophotographic photosensitive member 151) at the transfer nip portion.

  The transfer material P that has received the transfer of the toner image at the transfer nip is separated from the surface of the electrophotographic photosensitive member 151 and introduced into a fixing device (not shown), and the toner image is fixed and output as an image formed product. (In the case of the double-sided image forming mode or the multiple image forming mode, this image-formed product is introduced into a recirculation conveyance mechanism (not shown) and re-introduced into the transfer nip portion).

  The toner remaining on the surface of the electrophotographic photosensitive member 151 is collected by a cleaning blade (not shown). Thereafter, the surface of the electrophotographic photosensitive member 151 is again charged by the charging roller 153, and image formation is repeatedly performed.

  When the electroconductive roller produced in this example was mounted on the above-described electrophotographic apparatus and image output was performed, a very good image was obtained, so that this roller can obtain a good image over a long period of time. It became clear that it was an electroconductive roller as a charging member which can be used.

(Examples 2 to 7, Comparative Examples 1 to 6)
A conductive roller was produced in the same manner as in Example 1 except that the blending of the elastic layer and the surface layer was changed as shown in Table 1. The produced conductive roller was subjected to image evaluation by measuring the roller resistance value, outer diameter, and micro hardness in the same manner as in Example 1. The results are shown in Table 1.

  FIG. 6 is a schematic view showing a resistance value measuring device for a conductive roller which is a charging member of the present invention.

It is a figure which shows an example of schematic structure of the electrophotographic apparatus provided with the process cartridge which has an electrophotographic photoreceptor and the electroconductive roller of this invention. It is a figure which shows schematic structure of the electrophotographic apparatus used for the Example and the comparative example. It is a figure which shows the example of another layer structure of a roller-shaped charging member. It is a figure which shows the example of another layer structure of a roller-shaped charging member. It is a figure which shows the example of another layer structure of a roller-shaped charging member. It is the schematic which shows the resistance value measuring apparatus of the electroconductive roller which is a charging member of this invention.

Explanation of symbols

a support b elastic layer c surface layer d second surface layer e third surface layer 1 electrophotographic photosensitive member 2 shaft 3 charging member (charging roller)
4L exposure light (image exposure light)
DESCRIPTION OF SYMBOLS 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material 151 Electrophotographic photosensitive member 153 Charging roller 154 Laser beam scanner 154L Exposure light 155 Developing device 155a Toner carrier 155b Stirring member 155c Toner regulating member 156 Transfer roller S1 power supply S2 power supply 22 Conductive roller (charging roller)
31 Cylindrical electrode (metal roller)
32 Fixed resistor 33 Recorder (recorder)
S3 Bias application power supply

Claims (1)

This is a conductive roller used in electrophotographic equipment. Roller outer diameter (D1), micro hardness (H1), resistance value (R1) and resistance value (R1) after standing for 300 hours in an environment of 40 ° C x 95% RH A conductive roller characterized in that the relationship among the roller outer diameter (D0), micro hardness (H0), and resistance value (R0) of the roller satisfies all the following ranges.
0.8D0 ≦ D1 ≦ 1.2D0
0.5H0 ≦ H1 ≦ 1.5H0
0.1R0 ≦ R1 ≦ 10R0

Images