JP4822326B2 - Developing roller, manufacturing method thereof, electrophotographic process cartridge, and electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a developing roller, a manufacturing method thereof, an electrophotographic process cartridge and an electrophotographic image forming apparatus using the developing roller.

  In recent years, in an image forming apparatus of an electrophotographic apparatus such as a copying machine or an optical printer, a one-component developing device tends to be used as the main body is downsized. The one-component developing method using a one-component developer is a method that charges the developer on the developing roller by a developer amount regulating member that makes the developer on the developing roller a fixed amount or friction between the developing roller and the developer. A thin film is formed and conveyed to the development area by the rotation of the developing roller. In the developing region, the developer moves from the developing roller onto the electrostatic latent image on the latent image carrier to develop the electrostatic latent image.

  The one-component development method does not require carrier particles such as glass beads, iron powder, and ferrite, unlike the two-component development method, so that the development device itself can be reduced in size and weight. Furthermore, since the two-component development method needs to keep the developer concentration in the developer constant, a developer concentration detection device and a replenishment device that keeps the developer concentration constant are necessary. Cause weight and weight. In this respect as well, the one-component development method is advantageous for reduction in size and weight.

  The one-component development method is roughly classified into a magnetic one-component development method using a magnetic developer containing a magnetic substance in the developer and a non-magnetic one-component development method using a non-magnetic developer containing no magnetic substance. In a full-color printer, since the magnetic substance component is usually colored, a non-magnetic one-component developing method that does not contain a colored magnetic substance component is used.

  In a developing device using such a non-magnetic one-component developing method, a developing roller is provided so as to close an opening of a developer container that contains the developer and to expose a part of the developer outside the container. The developer is supplied onto the surface of the developing roller by an elastic roller provided in contact with the developing roller in the developer container. Next, the developer is restricted by a developer amount regulating member to form a thin film on the developing roller, and at the same time, a positive or negative charge is given to the toner particles by friction. Further, the developer charged positively or negatively by the rotation of the developing roller is conveyed to the developing area of the exposed portion, and is developed by being attached to the electrostatic latent image on the surface of the latent image carrier provided opposite thereto. A conductive roller is used as such a developing roller.

  Silicone rubber, acrylonitrile butadiene rubber, urethane rubber, epichlorohydrin rubber, and EPDM (ethylene-propylene-diene rubber) are used as the conductive material constituting the conductive developing roller. Further, a conductive material such as carbon black or metal powder is blended with these to impart desired conductivity to the developing roller. The development roller using such various rubbers has been improved in various ways to achieve higher quality so that a high-quality image can be formed.

Specifically, the storage shear elastic modulus of the elastic layer in the dynamic viscoelasticity at a frequency of 0.1 Hz is 1 × 10 ⁵ Pa or more and 6 × 10 ⁶ Pa or less, and the dynamic shear modulus at a frequency of 0.1 Hz. A conductive roller having a tan δ of viscoelasticity of 0.1 or less (Patent Document 1) has been reported. Moreover, the electroconductive roller which made the elastic layer foam and formed the non-foamed 2nd elastic layer in the outer periphery (patent document 2), or the electroconductive which formed the electroconductive urethane rubber layer on the outer periphery of the electroconductive ethylene propylene rubber layer Has been reported (Patent Document 3). The roller described in Patent Document 1 has a high hardness and may cause a density defect when used at a low temperature such as 10 ° C. or lower. Further, in the roller described in Patent Document 2, there is a possibility that a bubble mark of the foam layer appears on the image, resulting in an image defect. The roller described in Patent Document 3 may cause an image density defect when a normal softening agent is added.

Furthermore, the developing characteristics of such a developing roller may not be sufficient for high definition and high speed of recent electrophotographic apparatuses. For example, in an electrophotographic apparatus that outputs an image of 30 sheets / min in the vertical direction of A4 size at 1200 dpi, an image defect due to the developing roller may occur. For this reason, a higher level than the performance of the conventional developing roller is required.
JP 2004-271888 A JP-A-11-202615 JP-A-9-160369

  It is an object of the present invention to have uniform electrical characteristics, sufficient charging ability, low resistance applicable to high-speed electrophotographic apparatus, uniform electrical characteristics even after long-term use, and resistance stability High-quality image formation is possible by uniform charging friction of the developer even at low temperatures, and a developing roller excellent in fog resistance, its manufacturing method, an electrophotographic process cartridge using this, and an electrophotographic An object is to provide an image forming apparatus.

  The present inventors have made ethylene as a developing roller material capable of forming a high-quality image without generation of ozone in a situation where a higher speed of the image forming process of the electrophotographic apparatus is required. -Focused on propylene-diene terpolymer (EPDM). In the developing roller containing EPDM and a hydrocarbon plasticizer having a specific dynamic viscoelasticity in the elastic layer, a uniform image can be obtained, contamination of the photoreceptor and generation of odor are suppressed, and safety is improved. I got a high knowledge.

  Furthermore, it has been found that by providing a specific surface layer for this elastic layer, it is possible to suppress the adhesion of the developer to the surface and to suppress development defects, so-called ghosts, and based on this knowledge, the present invention has been completed. It was.

  That is, the present invention provides an electrophotographic developing roller having an elastic layer on a conductive metal core, wherein the elastic layer contains a rubber component containing 80% by mass or more of an ethylene-propylene-diene terpolymer, and 30% by mass. % To 70% by mass of the hydrocarbon plasticizer, the hydrocarbon plasticizer has a pour point at -50 ° C to -10 ° C, and the elastic layer has a frequency of 0. The present invention relates to a developing roller characterized in that tan δ of dynamic viscoelasticity at 1 Hz and a measurement temperature of −10 ° C. has a value greater than 0.10 and less than 0.90.

  The present invention also includes a developing device having the developing roller, a latent image carrier that is provided to face and contact the developing roller, and carries a latent image that is visualized by being attached with a developer carried by the developing roller, One or more of a charging member that charges the latent image carrier, a cleaning member that cleans the latent image carrier, and a transfer member that transfers the developer image on the latent image carrier to a recording medium. The present invention relates to an electrophotographic process cartridge and an electrophotographic image forming apparatus characterized by being integrated.

  The developing roller of the present invention includes an elastic layer having a specific viscoelasticity in an image forming process that requires high speed in an electrophotographic apparatus, and thus suppresses the deterioration of the developer, suppresses the occurrence of fogging, and is uniform. Image formation can be performed. In addition, ozone generation is low, safety is excellent, odor generation is suppressed, and durability is excellent.

  Further, according to the second invention of the present invention, the hydrocarbon plasticizer can be uniformly dispersed in the elastic layer, that is, the rubber component can be uniformly dispersed, and hardness unevenness can be suppressed and increased. A quality image can be obtained.

  According to the third invention of the present invention, it is possible to uniformly disperse the hydrocarbon-based plasticizer in the elastic layer, to suppress unevenness in hardness and obtain a high quality image, and to suppress bleeding. Contamination of the photoreceptor can be suppressed.

  According to the fourth and fifth aspects of the present invention, the filming of the developer can be suppressed. Filming is a phenomenon that causes toner that does not participate in development to adhere to the surface of the developing roller and causes image defects.

  According to the sixth aspect of the present invention, the developing roller can be produced efficiently and inexpensively by continuous production with a small number of steps.

  According to the seventh and eighth inventions of the present invention, even when using a high-speed image forming process, it is highly safe and suppresses the generation of odor, developer deterioration, and fogging, and uniform image formation. It can be performed and has excellent durability.

  The developing roller of the present invention is an electrophotographic developing roller having an elastic layer on a conductive metal core, wherein the elastic layer contains 80% by mass or more of ethylene-propylene-diene terpolymer (EPDM). And a hydrocarbon plasticizer in the range of 30% by mass to 70% by mass, the hydrocarbon plasticizer has a pour point at −50 ° C. or more and −10 ° C. or less, and the elastic layer is The dynamic viscoelasticity tan δ at a frequency of 0.1 Hz and a measurement temperature of −10 ° C. is greater than 0.10 and less than 0.90.

  As the conductive core bar used in the developing roller of the present invention, any material can be used as long as it is conductive. Specific examples include copper, aluminum, titanium, nickel, and alloys such as stainless steel such as SUS containing these metals, duralumin, brass, and bronze. Furthermore, the material can be appropriately selected from rigid and conductive materials such as carbon black or a composite material obtained by solidifying carbon fiber with plastic. Here, examples of the alloy steel include stainless steel, nickel chrome steel, nickel chrome molybdenum steel, chrome steel, chromium molybdenum steel, nitriding steel to which Al, Cr, Mo and V are added. From the viewpoint of strength and the like, a metal one is desirable.

  Furthermore, as the conductive metal core, a material obtained by subjecting the shaft body material to rust prevention treatment such as plating and oxidation treatment can be used. As the type of plating, both electroplating and electroless plating can be used, but electroless plating is preferable from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating (Kanizen plating), copper plating, gold plating, and other various alloy platings. Examples of the nickel plating include Ni-P, Ni-B, Ni-WP, and Ni-P-PTFE composite plating. The plating thickness can be 0.05 μm or more, for example, but considering the balance between work efficiency and rust prevention ability, the plating thickness is suitably 0.1 to 30 μm.

  Examples of the shape of the conductive metal core include a rod-shaped body or a pipe-shaped body. A primer treatment layer may be formed on the surface as necessary. Examples of the outer diameter of the conductive metal core include a range of 4 mm to 20 mm.

  The elastic layer in the developing roller of the present invention includes a rubber component containing 80% by mass or more of an ethylene-propylene-diene terpolymer (EPDM) and a hydrocarbon plasticizer.

  EPDM, which is the main component of the rubber component contained in the elastic layer, has excellent mechanical strength, and can impart excellent durability that can withstand image formation of thousands to tens of thousands of times to the developing roller. EPDM has a main chain made of saturated hydrocarbon, can suppress molecular cleavage by ozone, and has excellent ozone resistance. As the EPDM, industrially used ones can be used, and examples of the diene monomer as the third component include ethylidene norbornene, hexadiene, octadiene and the like. Of these, EPDM containing ethylidene norbornene as the third component is preferably used because it has a high crosslinking rate and a good balance of physical properties. Moreover, EPDM can also be used 1 type or in mixture of 2 or more types according to the objective.

  Such an EPDM preferably has an iodine value of 10 or more and 40 or less from the viewpoint of the dispersibility of the hydrocarbon plasticizer and the elasticity of the elastic layer. Furthermore, what has the value of 12-30 is more suitable. If the iodine value of EPDM is 10 or more, it is excellent in dispersibility of hydrocarbon plasticizer in the elastic layer, can suppress the occurrence of hardness unevenness in the developing roller, and reduce the stress load on the developer. Can do. If the iodine value of EPDM is 40 or less, rubber elasticity can be maintained in the developing roller layer, and occurrence of fogging can be suppressed. It is possible to use a mixture of two or more different iodine values as EPDM, but the iodine value in that case can be determined by a value calculated by a geometric mean. Further, as described later, ethylene-propylene rubber (EPM) containing no third diene component can be used in combination as a rubber component. In this case, the iodine value is absorbed with respect to the total mass of EPDM and EPM. The value of iodine mass can be adopted.

  In addition, the above EPDM has been marketed as an oil-extended process oil such as a hydrocarbon plasticizer for the purpose of improving processability, but both oil-extended and non-oil-extended can be used. In the case of oil-extended EPDM, the mass of EPDM is the net mass of EPDM obtained by subtracting the mass of hydrocarbon-based plasticizer from the total mass of oil-extended EPDM. The hydrocarbon plasticizer used in the process oil when using oil-extended EPDM is grasped as the hydrocarbon plasticizer component contained in the elastic layer together with the rubber component, and its content is not a rubber component but a hydrocarbon. To be added to the plasticizer.

  As such an EPDM, those that are practically used industrially include, specifically, Esprene 201, 301, 305, 400, 501A, 502, 505, 505A, 512F, 514F, 522, 524, 532, 552. 553, 567, 582F, 586, 600F, 601F, 606, 670F, 671F, 673, 5214, 5754, 6506S, 6182F, etc. (manufactured by Sumitomo Chemical Co., Ltd.), JSR EP912P, EP01P, EP02P, EP941P, EP961SP, EP07P EP57P, EP181SP, EP11, EP43, EP93, EP24, EP27, EP21, EP132, EP22, EP25, EP33, EP35, EP37C / F, EP65, EP51, EP57C / F, EP75F, EP8 6, EP96, EP98, EP103AF, EP106EF, EP107F, EP801E, EP001DE, etc. (manufactured by JSR Corporation), NORDEL 1040, 1070, 1145, 1320, 1440, 1470, 1660, 2522, 2722 / P, 2744 / P, 2760 / P, etc. (manufactured by DuPont), Epsyn 40-A, 70-A, 55, 2308, 2506, 4506, 4906, 5206, 5508, 5805, 7506, E801, N557, N597, N997, P557, P558, P597, MDE239 , MDE248 and the like (manufactured by Copolymer Rubber and Chemical Corporation (USA)), POLYSAR 227, 306, 345, 585, 487XP, 865, 965, 5465, 5672 , And the like can be exemplified such as 5875,6463 (policer Rubber Corporation (Made in USA)).

  In addition to EPDM, the rubber component includes rubbers such as ethylene-propylene rubber (EPM), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and elastomers such as polyethylene, polypropylene, and certain polyesters. It may be.

  As content of EPDM, 80 mass% or more is preferable in the rubber component contained in an elastic layer. If it is 80 mass% or more, sufficient strength can be exhibited in the developing roller, and the durability is excellent.

  For such rubber components, conductive agents, fillers, extenders, vulcanizing agents, cross-linking agents, vulcanizing aids, cross-linking aids, antioxidants, anti-aging agents can be used as long as they do not impair the function. Various additives such as an additive and a processing aid can be contained.

  The hydrocarbon-based plasticizer contained in the elastic layer of the developing roller of the present invention has good compatibility with EPDM, can suppress elution from the elastic layer and suppress contamination of the photoreceptor, Compared with a plasticizer, it is excellent in terms of low cost, excellent safety, and suppression of odor generation.

  The hydrocarbon-based plasticizer has a pour point in the range of −50 ° C. to −10 ° C. If the pour point is −50 ° C. or higher, it is possible to suppress the occurrence of a difference in image density that appears as a band-like pattern on the image due to bleeding. The agent is well dispersed in the elastic layer, and the occurrence of uneven hardness of the developing roller can be suppressed.

  Examples of the hydrocarbon plasticizer include polybutadiene, hydrogenated polybutadiene, polyisoprene, polyisobutene, paraffin hydrocarbon, naphthene hydrocarbon, and the like. These may be used alone or in combination of two or more. be able to. Of these, paraffinic hydrocarbons and naphthenic hydrocarbons are preferable because of compatibility with EPDM and non-contamination with respect to the photosensitive drum. Specific examples of commercially available products include shelf rex (manufactured by Shell Chemical Co., Ltd.), Diana Process Oil (manufactured by Idemitsu Kosan Co., Ltd.), Dimaron, YS oil (manufactured by Yasuhara Chemical Co., Ltd.), and liquid paraffin.

  Furthermore, the content of the paraffinic plasticizer in the total hydrocarbon plasticizer is more preferably 20% by mass or more and 80% by mass or less. If the content of the paraffinic plasticizer is 20% by mass or more, the dispersibility of the EPDM in the elastic layer can be improved, and if it is 80% by mass or less, the density of the image even in an atmosphere of 5 ° C. or less. Unevenness can be suppressed.

  The content of the hydrocarbon-based plasticizer in the elastic layer is in the range of 30% by mass to 70% by mass with respect to the entire elastic layer, but is preferably in the range of 40% by mass to 70% by mass. . If the content of the hydrocarbon plasticizer in the elastic layer is 30% by mass or more, the dispersibility of the hydrocarbon plasticizer in the elastic layer is good, and the inclusion of the hydrocarbon plasticizer in the elastic layer If the amount is 70% by mass or less, bleeding can be suppressed. In particular, when paraffinic hydrocarbons and naphthenic hydrocarbons are contained as the hydrocarbon plasticizer, the content of the paraffinic plasticizer in the hydrocarbon plasticizer is more preferably 20% by mass or more and 80% by mass or less. In the case of this range, the content of the hydrocarbon-based plasticizer in the elastic layer is preferably in the range of 40% by mass to 70% by mass.

  In the elastic layer, in addition to the EPDM and the carbon-hydrogen plasticizer, a conductive agent, a filler, an extender, a vulcanizing agent, a cross-linking agent, and a vulcanizing auxiliary agent are added as necessary without impairing these functions. Various additives such as a crosslinking aid, an antioxidant, an anti-aging agent, and a processing aid can be added.

  The vulcanizing agent cures the rubber component. For example, organic sulfur-containing compounds such as tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), N, N'-dithiobismorpholine, sulfur, etc. -Butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-bis (tert-butylperoxy) cyclododecane, 2,2-bis (tert-butylperoxy) octane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 1,3-bis (tert-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl Peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl It can be an organic peroxide-based crosslinking agents such as peroxy benzoate. As a usage-amount of a crosslinking agent, the range of 0.1-20 mass parts is preferable with respect to 100 mass parts of rubber components, More preferably, it is 0.1-10 mass parts.

  Examples of the crosslinking aid include ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol dimethacrylate, and 1,4-butane. Diol diacrylate, 1,6-hexanediol diacrylate, 2,2′-bis- (4-methacryloyldiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol reacrylate, divinylbenzene, N, N′-methylenebisacrylamide, p-quinonedioxime, p, p′-dibenzoylquinonedioxime, triazinedithiol, triallyl cyanurate, triallyl isocyanurate, bisma A reimide etc. can be mentioned. As usage-amount of a crosslinking adjuvant, 0.01-20 mass parts can be mentioned with respect to 100 mass parts of rubber components, for example. If the amount of the crosslinking aid used is 0.01 parts by mass or more, the crosslinking density is high and excellent in mechanical strength and low compression set. On the other hand, if it is 20 parts by mass or less, the crosslinking density is increased. It is possible to suppress the hardness from rising excessively.

  Examples of the conductive agent include metal powders and fibers such as aluminum, palladium, iron, copper, and silver, carbon black, metal powder, metal oxides such as titanium oxide, tin oxide, and zinc oxide, copper sulfide, and sulfide. Examples thereof include metal compound powders such as zinc. In addition, the surface of particles suitable as a conductive agent is electrolytically treated and sprayed with tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, rhodium. You may use the powder adhere | attached by coating and mixing shake. In addition, carbon black conductive agents such as acetylene black, ketjen black, PAN carbon black, and pitch carbon black can be used as the conductive agent. Among these, the carbon black conductive agent has performance, quality, It is preferable from the viewpoint of cost.

  Examples of fillers and extenders include fumed silica, wet silica, quartz fine powder, diatomaceous earth, carbon black, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, Examples include talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, glass fiber, organic reinforcing agent, and organic filler. Further, the surface of these fillers can be used after being hydrophobized by treatment with an organosilicon compound such as polydiorganosiloxane.

  As antioxidant, it is well-known used with respect to high molecular compounds, such as a hindered phenolic antioxidant, a phenolic antioxidant, phosphorus antioxidant, an amine antioxidant, and sulfur antioxidant. Material can be used.

  Examples of the antiaging agent include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

  Examples of processing aids include fatty acids such as stearic acid and oleic acid, or metal salts and esters of fatty acids.

  Such an elastic layer has a value of tan δ of dynamic viscoelasticity at a frequency of 0.1 Hz and a measurement temperature of −10 ° C., which is larger than 0.10 and smaller than 0.90. The tan δ of dynamic viscoelasticity is a value obtained by applying a frequency of 0.1 Hz to the elastic layer in an atmosphere of −10 ° C., applying stress, and measuring the strain. When the tan δ of dynamic viscoelasticity of the elastic layer is large, the ability not to give stress to the developer is large. When the dynamic viscoelasticity tan δ at the frequency of the elastic layer of 0.1 Hz and the measurement temperature of −10 ° C. is larger than 0.10, it is possible to suppress the occurrence of fog without applying stress to the developer. When the tan δ of the dynamic viscoelasticity of the elastic layer is less than 0.90, the stress applied to the developer is small and the deterioration of the developer can be suppressed, and excellent image formation is performed even in an atmosphere of 5 ° C. or less. be able to.

  Here, as the measurement of tan δ of the dynamic viscoelasticity of the elastic layer, for example, a sample loaded with a sine wave displacement with a frequency of 0.1 Hz is used as a viscoelasticity measuring device (RSA-II: manufactured by Rheometrics). Thus, the value at −10 ° C. when tan δ of dynamic viscoelasticity is measured while increasing the temperature from −80 ° C. to 40 ° C. at a rate of 3 ° C./min can be employed.

  Furthermore, the developing roller of the present invention preferably has a surface layer that can suppress filming of the developer with respect to the elastic layer.

  As the material for the surface layer, if a trace of deformation remains, it will appear as an image defect. Therefore, a material having durability against compression set at the ambient temperature to be used is preferable. As the material of the surface layer, polyamide resins, fluororesins, styrene resins, vinyl resins, polycarbonate resins, acrylic resins, and other thermoplastic resins, epoxy resins, polyester resins, alkyd resins, phenolic resins, melamine resins, polyurethane resins, A thermosetting resin such as urea resin, silicon resin, polyimide resin, or photocurable resin can be used. Of these, polyurethane resins are preferred because of excellent toner filming. Examples of the polyurethane resin include a polyurethane resin obtained by a polyaddition reaction between a polyol and a polyisocyanate, and a urethane rubber treated with an aromatic diamine or a polyhydric alcohol.

  Examples of the polyol include polyether polyol, polyethylene glycol, polypropylene glycol, and copolymers or mixtures thereof, polyalkylene glycol, polytetramethylene ether glycol, a copolymer of tetrahydrofuran and alkylene oxide, polyester polyol, Examples thereof include ether polyester polyol, polyester amide polyol, acrylic polyol, polycarbonate polyol, and mixtures thereof.

  Of these, polyether polyols are preferred, and those having a mass average molecular weight Mw of 5000 to 20000 and a molecular weight distribution Mw / Mn of 2.5 or less are preferred because ghosts can be suppressed in the formed image. Ghost refers to a phenomenon in which a previous latent image remains on an image to which toner is to be transferred, and the image is whitened.

  Examples of the polyisocyanate include triene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hydrogenated MDI, crude MDI, xylylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI). ), Isophorone diisocyanate (IPDI), and the like.

  When a polyurethane is produced by reacting the above polyol with a polyisocyanate, the blending ratio is set as follows: an isocyanate group [NCO] of the polyisocyanate and a hydroxyl group [OH] molar ratio [NCO] / [OH] of the polyol. The range of 9 or more and 1.4 or less is preferable. When the molar ratio of [NCO] / [OH] is within this range, a surface layer having a high hardness can be obtained as the degree of polymerization of polyurethane, and surface contamination due to precipitation of unreacted urethane monomer can be suppressed.

  In order to impart image forming characteristics to the surface layer, a conductive agent, fine particles, an extender and the like can be appropriately contained as necessary. Examples of the conductive agent include metal powders and fibers such as aluminum, palladium, iron, copper, and silver, carbon black, metal powders, metal oxides such as titanium oxide, tin oxide, and zinc oxide, copper sulfide, Mention may be made of metal compound powders such as zinc sulfide. Furthermore, the surface of particles suitable as a conductive agent is subjected to electrolytic treatment and spray coating of tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, rhodium. It is possible to use the powder adhered by the process and mixed shaking. Furthermore, carbon powders such as acetylene black, ketjen black, PAN-based carbon black, and pitch-based carbon black can be used as the conductive agent. Of these conductive agents, carbon black is preferred because it can reduce the electrical resistivity when added in a small amount and can impart conductivity without increasing the hardness of the rubber composition.

  The thickness of the surface layer is preferably 3 μm or more from the viewpoint of suppressing the precipitation of low molecular weight components and the like and contaminating the photoreceptor, and 500 μm from the viewpoint of suppressing the fusion of the developer due to the developing roller becoming hard. The following is preferred. More preferably, it is 5-30 micrometers.

The developing roller of the present invention preferably has a volume resistivity in the range of 1 × 10 ⁴ to 1 × 10 ⁸ Ωcm. When the volume resistivity of the developing roller is 1 × 10 ⁴ Ωcm or more, if there is a defective portion of the photoreceptor, generation of a current leak can be suppressed and a good image can be obtained, and if it is 1 × 10 ⁸ Ωcm or less. For example, the occurrence of image defects such as insufficient density of the solid image can be suppressed.

  Examples of the method for producing the developing roller of the present invention include a method for producing the elastic layer by a method such as an extrusion molding method, a mold molding method, and an injection molding method. Of these methods, the extrusion molding method is preferable. The extrusion method has fewer steps than a batch type production method such as a mold, and can produce the developing roller efficiently and at low cost by continuous production.

  As a method for forming the surface layer on the elastic layer, the material constituting the surface layer is dispersed using a dispersing device using beads such as a sand mill, a paint shaker, a dyno mill, a pearl mill, etc., to prepare a coating liquid, and this is applied. The method of crafting can be used. Examples of the coating method of the prepared coating liquid include a coating method, a dipping method, a spray method, and the like, but a dipping method can be used as a preferable method.

  When forming the surface layer, the surface of the elastic layer may be modified by a surface modification method such as corona treatment, flame treatment, or excimer treatment in order to improve adhesion between the elastic layer and the surface layer and suppress peeling. preferable.

  As such a developing roller of the present invention, it is sufficient if it has an elastic layer on the conductive core as described above, and preferably a surface layer can be mentioned, but it has other functional layers. It may be a thing. Specifically, the developing roller of the present invention has an elastic layer 2 on a conductive core 1 as shown in FIG. 1, and an elastic layer 2 on the conductive core 1 as shown in FIG. The surface layer 3 can be sequentially laminated.

  The electrophotographic image forming apparatus of the present invention has the above-described developing roller. As an example, a color electrophotographic image forming apparatus shown in FIG. The color electrophotographic image forming apparatus shown in the schematic configuration diagram of FIG. 3 has an image forming unit provided for each color toner such as yellow toner Y, magenta toner M, cyan toner C, and black toner BK. Each image forming unit is provided with a photosensitive drum 5 as a latent image carrier that rotates in the direction of the arrow. Around each photosensitive drum, there are a charging member 12 for uniformly charging the photosensitive drum, exposure means for irradiating the uniformly charged photosensitive drum with laser light 11 to form an electrostatic latent image, electrostatic A developing device 10 is provided that supplies toner to the photosensitive drum on which the latent image is formed to develop the electrostatic latent image. Further, a transfer roller for transferring the visualized toner image on the photosensitive drum onto the recording medium by applying a bias power supply 18 from the back surface of the recording medium 22 such as paper supplied by the paper feeding roller 23 and conveyed by the conveying belt 20. A transfer member having 17 is provided. The conveying belt 20 is suspended from the driving roller 16, the driven roller 22, and the tension roller 19, and is synchronized with the image forming unit so that the toner images of the respective colors formed by the respective image forming units are sequentially superimposed and transferred onto the recording medium. The recording medium is controlled to move and transport the recording medium.

  Further, the color electrophotographic image forming apparatus includes a fixing device 15 that fixes a toner image superimposed and transferred onto a recording medium by heating and the like, and a conveyance device (not shown) that discharges the recording medium on which the image has been formed to the outside of the apparatus. ) And are provided.

  On the other hand, each image forming unit accommodates a cleaning member having a cleaning blade 14 for removing a residual transfer developer remaining without being transferred onto each photosensitive drum and cleaning the surface, and a developer scraped off from the photosensitive drum. A waste developer container 13 is provided. The cleaned photosensitive drum is set in a state where image formation is possible and waits.

  The developing device 10 provided in each of the image forming units is installed so as to close a developer container 8 containing toner and an opening of the developer container, and is opposed to the photosensitive drum at a portion exposed from the developer container. A developing roller 6 is provided. In the developer container, a roller-shaped developer application member 7 that contacts the developing roller and supplies toner to the developing roller, and the toner supplied to the developing roller is formed in a thin film shape, and the amount of developer that is frictionally charged is regulated. A member 9 is provided. Examples of the developer applying member 7 include a foamed sponge body or polyurethane foam on a shaft core body, a fur brush structure in which fibers such as rayon and polyamide are implanted, and toner for a developing roller. This is preferable from the viewpoint of removing residual toner after supply and development. The developer application member is preferably arranged with an appropriate contact width with the developing roller, and is preferably rotated with a relative speed at the contact portion with respect to the developing roller.

  The electrophotographic process cartridge of the present invention is provided with a developing device having the developing roller, and a latent image that is provided so as to face and contact the developing roller and to which a developer carried by the developing roller is attached and visualized. One or two of a latent image carrier, a charging member that charges the latent image carrier, a cleaning member that cleans the latent image carrier, and a transfer member that transfers a developer image on the latent image carrier to a recording medium The above is provided integrally. Specifically, the developing device 10 is provided, and one or more of the photosensitive drum 5, the charging member 12, the cleaning member 14, and the transfer member are integrally held, and can be attached to and detached from the image forming apparatus. The provided thing can be mentioned.

  Hereinafter, the developing roller, the electrophotographic process cartridge, and the electrophotographic image forming apparatus of the present invention will be described in detail, but the technical scope of the present invention is not limited thereto. Hereinafter, unless otherwise specified, commercially available high-purity products were used as reagents.

[Example 1]
[Production roller development]
As EPDM, 100 parts by mass of Esprene 505 (manufactured by Sumitomo Chemical Co., Ltd.), 57 parts by mass of P-300 (manufactured by Shell Chemical) (pour point-12.5 ° C.) as a hydrocarbon plasticizer, and stearic acid as a processing aid 1 part by mass, 30 parts by mass of MT carbon black Thermacs flow foam N990 (manufactured by CANCAB) as a filler, 1 part by mass of sulfur as a vulcanizing agent, and 1 part by mass of mercaptobenzothiazole (MBT) as a vulcanization aid It mixed with the open roll and the unvulcanized rubber composition of the elastic body was obtained.

  The obtained unvulcanized rubber composition was extruded into a tube shape by a vent type rubber extruder (caliber 50 mm vent extruder L / D = 16, manufactured by EM Giken Co., Ltd.), and 30 ° C. at 160 ° C. with pressurized steam using a vulcanized can. The rubber tube having an outer diameter of 14 mm, an inner diameter of 5.5 mm, and a length of 250 mm was prepared.

  Next, the aforementioned rubber tube is press-fitted into a cylindrical conductive cored bar (made of steel, made of steel, the surface is nickel-plated) having a diameter of 6 mm and a length of 252 mm, with a primer applied to the central part 232 mm in the axial direction. Then, secondary vulcanization and adhesion treatment were performed in a hot air oven at 160 ° C. for 2 hours. The rubber after the vulcanization was cut off at both ends of the rubber to make the length of the rubber part 232 mm, and then the rubber part was polished with a rotating grindstone to produce a developing roller having a linear elastic layer with a diameter of 12 mm.

[Tan δ measurement of dynamic viscoelasticity of elastic layer]
An unvulcanized rubber composition having the same composition as the elastic layer was put into a mold having a width of 10 mm, a length of 150 mm, and a thickness of 2 mm, and pressurized with a press set at a mold temperature of 160 ° C. for 30 minutes. After cooling the mold, the sheet sample was taken out of the mold to prepare a dynamic viscoelastic tan δ measurement sheet. A small piece for measurement is cut out from the taken sheet sample, and this is loaded with a displacement of a sinusoidal wave with a frequency of 0.1 Hz on a viscoelasticity measuring device RSA-II (manufactured by Rheometrics Co., Ltd.) at 3 ° C from -80 ° C to 40 ° C. Tan δ was measured while increasing the temperature at a rate of / min, and tan δ at −10 ° C. was read.

  The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 30% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.11.

[Image characteristics]
The obtained developing roller is incorporated into the developing device shown in FIG. 3, and a color laser printer LASERJET 3600 (manufactured by Hewlett-Packard Japan) is modified using a modified machine so that the developing device can be attached, and the ghost, Bass formation images were evaluated.

[Cover]
Using the modified machine, continuous image formation was performed with 2% printing under high-temperature and high-humidity conditions at a temperature of 30 ° C. and a relative humidity of 80%, and it was determined whether there was a problem in image quality formed after printing 3500 sheets. Based on the judgment, evaluation was made according to the following criteria.
◎: Good that is not confirmed with the naked eye ○: Fog is small and there is no problem on image Δ: Fog is confirmed ×: Severe rash is confirmed

[Low-temperature image]
Using the modified machine, a solid image was printed under high temperature and high humidity conditions of a temperature of 10 ° C. and a relative humidity of 10%. The obtained solid image was measured at 9 points for each image using a Macbeth Color Checker RD-1255 (manufactured by Macbeth Co.) in an environment of a temperature of 25 ° C. and a relative humidity of 50% RH. The difference of was compared.
A: The difference between the maximum value and the minimum value of the solid density is 0.1 or less. ○: The difference between the maximum value and the minimum value of the solid density is 0.2 or less. Δ: The difference between the maximum value and the minimum value of the solid density is 0.3. X: The difference between the maximum value and the minimum value of the solid density is greater than 0.3.

[Bleed]
Using the above-mentioned modified machine, leave the machine at an ambient temperature of 40 ° C and a relative humidity of 95% for 1 month, then disassemble the process cartridge in a normal temperature and humidity environment, and check whether the bleed material adheres to the photoconductor. The presence or absence of surface exudation was visually observed.
A: There is no adhesion to the photoconductor, and there is no oozing on the surface of the developing roller. O: There is no adhesion to the photoconductor, but a slight oozing is seen on the surface of the developing roller. △: There is no adhesion to the photoconductor. However, seepage is seen on the surface of the developing roller. X: Adhesion to the photoreceptor is observed.

[Dispersibility of hydrocarbon plasticizer]
Measure ASKER-C hardness of developing roller with ASKER rubber hardness meter C type (manufactured by Kobunshi Keiki Co., Ltd.) in an environment of temperature 25 ° relative humidity 50%, 5 points in the longitudinal direction and 4 points in the circumferential direction for a total of 20 points. The difference between the maximum value and the minimum value among the 20 points was determined according to the following criteria. ASKER-C was visually read to one decimal place.
A: Extremely small variation at 1.0 or less. O: No problem for use as a developing roller at 1.5 or less. Δ: Variation at 2.0 or less. X: Large variation at 2.0 or more.

[Filming]
Using the modified machine, 3500 continuous images were formed with 2% printing under high temperature and high humidity conditions of 30 ° C and 80% relative humidity. After the evaluation image was drawn, the process cartridge was disassembled and developed. The roller and image were confirmed and evaluated according to the following criteria.
A: No filming O: No problem in image, but slightly occurring on developing roller Δ: Slightly occurring in image ×: Occurring on image

[set]
After being left in a process cartridge state for 1 month at a temperature of 40 ° C and a relative humidity of 95%, and then left for 1 day in a room temperature and humidity environment, the process cartridge is incorporated into the modified machine, and images are formed for evaluation. It was.
◎: Press-contact marks are not visible on the image ○: Press-contact marks are very thin but do not affect the image △: Press-contact marks are thin and affect the image ×: The press-contact marks are clearly visible That affect the image.

[ghost]
Using the above-mentioned modified machine, continuous image formation with a printing rate of 2% was performed. After printing 3,500 sheets, the 3501st image for ghost evaluation (a pattern in which a 15 mm square solid image and a halftone image are continuously formed in one image) ) Was formed. The ghost level was judged by visually evaluating the occurrence of non-uniform density in the halftone portion.
A: No ghost is generated. B: A ghost is slightly generated but there is no problem in the image. Δ: A ghost is generated. X: A ghost is remarkably generated.

[Comprehensive evaluation]
Based on the above evaluation results, a comprehensive performance evaluation was performed, and the following four categories were evaluated.
A: Extremely good O: Good Δ: Slightly difficult and problematic in practical use ×: There is an obvious problem and it is not at a practical level.

[Example 2]
A developing roller was produced in the same manner as in Example 1 except that the elastic layer was formed with 300 parts by mass of the hydrocarbon-based plasticizer P-300. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
A developing roller was produced in the same manner as in Example 1 except that PW-380 (pour point—15 ° C., manufactured by Idemitsu Kosan Co., Ltd.) was used as the hydrocarbon plasticizer, and the elastic layer was formed with an addition amount of 57 parts by mass. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 30% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.11. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 4]
A developing roller was produced in the same manner as in Example 1 except that PW-380 was used as the hydrocarbon plasticizer and the elastic layer was formed with an addition amount of 300 parts by mass. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 5]
Using the same unvulcanized rubber composition as that of the elastic layer of Example 4, an elastic layer was formed by a mold forming method to prepare a developing roller. Specifically, the shaft core was placed in a mold, and the unvulcanized rubber composition was press-fitted into the mold cavity. Subsequently, the mold was heated at 150 ° C. for 30 minutes to cure the unvulcanized rubber composition. After cooling the mold, the produced roller was removed and further heated at 200 ° C. for 4 hours to obtain a roller having an outer diameter of 14 mm, an inner diameter of 5.5 mm, and a length of 250 mm. After cutting off both ends of the elastic layer of this roller to make the length of the elastic layer 232 mm, the outer periphery was polished with a rotating grindstone to produce a developing roller having a linear elastic body layer with a diameter of 12 mm.

  The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 6]
A developing roller was produced in the same manner as in Example 1 except that the elastic layer was formed using 300 parts by mass of esprene 567 as EPDM and 300 parts by mass of the hydrocarbon-based plasticizer P-300. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 7]
A developing roller was produced in the same manner as in Example 1 except that the elastic layer was formed using 300 parts by mass of esprene 586 as EPDM and 300 parts by mass of the hydrocarbon-based plasticizer P-300. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 8]
As EPDM, 50 parts by mass of esprene 505 and 50 parts by mass of esprene 600F (including 50 parts by mass of EPDM, 50 parts by mass of oil-extended paraffinic plasticizer (pour point -15 ° C)), hydrocarbon plastic A developing roller was produced in the same manner as in Example 1 except that the elastic layer was formed with 120 parts by mass of the agent PW-380. The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 56% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.88. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 9]
Developed in the same manner as in Example 1 except that the elastic layer was formed by using 240 parts by mass of P-300 as a hydrocarbon plasticizer and 60 parts by mass of naphthenic plasticizer FUCKOL 1060W (pour point -50 ° C. manufactured by Fuji Kosan). A roller was produced. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 10]
Developed in the same manner as in Example 1 except that the elastic layer was formed using 60 parts by mass of P-300 as a hydrocarbon plasticizer and 240 parts by mass of a naphthenic plasticizer FUCKOL 1060W (pour point -50 ° C. manufactured by Fuji Kosan). A roller was produced. The content of the hydrocarbon-based plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 11]
Developed in the same manner as in Example 1 except that the elastic layer was molded with 150 parts by mass of P-300 as a hydrocarbon plasticizer and 150 parts by mass of a naphthenic plasticizer FUCKOL 1060W (pour point -50 ° C. manufactured by Fuji Kosan). A roller was produced. The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 69% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.50. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 12]
As the surface layer material, Nipponran 5033 (manufactured by Nippon Polyurethane Co., Ltd.) was used, and 20 parts by mass of isocyanate coronate L (manufactured by Nippon Polyurethane Co., Ltd.) was added as a curing agent. It was set to 1.2. Further, an appropriate amount of carbon black MA100 (manufactured by Mitsubishi Chemical Corporation) was added to adjust the volume resistance value at the time of curing the surface layer to 10 ⁷ Ωcm to prepare a mixed solution. An organic solvent was added to this mixed solution, and urethane resin particles CFB-101-40 (φ16 μm, Dainippon Ink and Chemicals, Inc.) were prepared so that the thickness of the surface layer was 20 μm and the solid content was adjusted in the range of 20% to 30%. 5 parts by mass) was added, uniformly dispersed, and mixed to prepare a raw material liquid for the surface layer. In this raw material solution for the surface layer, the developing roller obtained in Example 8 was dipped and coated, then pulled up and dried, and heat-treated at 130 ° C. for 20 minutes to form a surface layer of about 20 μm on the outer circumference of the elastic layer. Molded into. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 13]
As a material for the surface layer, 100 parts by mass of polytetramethylene glycol PTG1000SN (molecular weight Mn = 1000, f = 2, manufactured by Hodogaya Chemical Co., Ltd.), isocyanate Millionate MT (MDI, f (average functional group number) = 2, Nippon Polyurethane 19.9 parts by mass) (manufactured by Kogyo Co., Ltd.) are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 3 hours under a nitrogen atmosphere. The molecular weight Mw = 5000 and the molecular weight dispersity Mw / Mn = 2.5. A bifunctional polyurethane polyol prepolymer was obtained.

Add 100 parts by mass of the above polyurethane polyol prepolymer and 16.1 parts by mass of isocyanate Takenate B830 (TMP-modified TDI, equivalent to f = 3, manufactured by Mitsui Takeda Chemical Co., Ltd.), and the molar ratio of [NCO] / [OH] Was set to 1.2. Further, an appropriate amount of carbon black MA100 was added to adjust the resistance value so that the volume resistance value at the time of curing the surface layer was 10 ⁷ Ωcm to prepare a mixed solution. A raw material liquid for the surface layer containing urethane resin particles was produced in the same manner as in Example 12 except that this mixed liquid was used, and a surface layer was produced. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 14]
As the surface layer material, except that the reaction time of polytetramethylene glycol and isocyanate was changed to 2 hours, and a bifunctional polyurethane polyol prepolymer having a molecular weight Mw = 5000 and a molecular weight dispersity Mw / Mn = 3.0 was used, A surface layer was produced in the same manner as in Example 13. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 15]
As the material for the surface layer, except that the reaction temperature of polytetramethylene glycol and isocyanate was changed to 100 ° C., and a bifunctional polyurethane polyol prepolymer having a molecular weight Mw = 20000 and a molecular weight dispersity Mw / Mn = 2.5 was used. A surface layer was produced in the same manner as in Example 13. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Example 16]
As a surface layer material, the reaction temperature of polytetramethylene glycol and isocyanate is changed to 100 ° C., the reaction time is changed to 2 hours, and a bifunctional polyurethane polyol prepolymer having a molecular weight Mw = 20000 and a molecular weight dispersity Mw / Mn = 3.0. A surface layer was produced in the same manner as in Example 13 except that was used. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 1 shows the evaluation results of the image characteristics.

[Comparative Example 1]
A developing roller was produced in the same manner as in Example 1 except that EPDM was changed to 100 parts by mass of Esprene 201 (manufactured by Sumitomo Chemical Co., Ltd.). The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 30% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.10. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

[Comparative Example 2]
A developing roller was produced in the same manner as in Example 1 except that the hydrocarbon-based plasticizer P-300 was changed to 30 parts by mass. The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 18% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.08. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

[Comparative Example 3]
A developing roller was produced in the same manner as in Example 1 except that the hydrocarbon-based plasticizer P-300 was changed to 400 parts by mass. The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 75% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.90. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

[Comparative Example 4]
A developing roller was produced in the same manner as in Example 1 except that the hydrocarbon plasticizer PW-380 was changed to 7 parts by mass. The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 5% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.05. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

[Comparative Example 5]
A developing roller was produced in the same manner as in Example 1 except that the hydrocarbon plasticizer was changed to 57 parts by mass of N-40 (shell chemical pour point -55 ° C.). The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 30% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.10. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

[Comparative Example 6]
A developing roller was prepared in the same manner as in Example 1 except that the hydrocarbon plasticizer was changed to 57 parts by mass of Lubuflex 100 (shell chemical pour point -5 ° C). The content of the hydrocarbon plasticizer in the elastic layer of the obtained developing roller was 30% by mass, and the tan δ at −10 ° C. of the elastic layer was 0.10. The resulting developing roller was evaluated for image characteristics in the same manner as in Example 1. Table 2 shows the evaluation results of the image characteristics.

It is a schematic perspective view which shows an example of the developing roller of this invention. It is a schematic perspective view which shows an example of the developing roller of this invention. It is a typical block diagram which shows an example of the electrophotographic image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive metal core 2 Elastic layer 3 Surface layer 5 Photosensitive drum 6 Developing roller 7 Elastic roller 8 Developer container 9 Developer amount control blade 10 Developing device 11 Laser beam 12 Charging member 13 Waste developer container 14 Cleaning blade 15 Fixing device 16 Drive roller 17 Transfer roller 18 Bias power supply 19 Tension roller 20 Conveying belt 21 Driven roller 22 Recording medium 23 Paper feed roller

Claims (8)

  In an electrophotographic developing roller having an elastic layer on a conductive metal core, the elastic layer contains a rubber component containing 80% by mass or more of an ethylene-propylene-diene terpolymer, and 30% by mass or more and 70% by mass or less. The hydrocarbon plasticizer has a pour point between −50 ° C. and −10 ° C., and the elastic layer has a frequency of 0.1 Hz and a measurement temperature of −10. A developing roller having a value of tan δ of dynamic viscoelasticity at ℃ of more than 0.10 and less than 0.90.   The developing roller according to claim 1, wherein the ethylene-propylene-diene terpolymer has an iodine value of 10 or more and 40 or less.   3. The developing roller according to claim 1, wherein the hydrocarbon plasticizer contains a naphthenic plasticizer and a paraffinic plasticizer in the range of 20% by mass to 80% by mass.   The developing roller according to claim 1, further comprising a surface layer containing a polyurethane resin.   The polyurethane resin in the surface layer contains a polymer of polyether polyol and isocyanate, the polyether polyol has a weight average molecular weight Mw of 5000 ≦ Mw ≦ 20000, and a molecular weight distribution Mw / Mn of 2.5 or less. The developing roller according to claim 4.   6. The method for producing a developing roller according to claim 1, wherein the elastic layer is formed by extrusion molding.   A developing device having the developing roller according to any one of claims 1 to 5, and a latent image that is provided to face and contact the developing roller and carries a latent image that is visualized by being attached with a developer carried by the developing roller. One or two of a carrier, a charging member that charges the latent image carrier, a cleaning member that cleans the latent image carrier, and a transfer member that transfers a developer image on the latent image carrier to a recording medium An electrophotographic process cartridge comprising the above integrated. An electrophotographic image forming apparatus comprising the developing roller according to claim 1.

Images