JP2007286498A - Conductive roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stably manufactured conductive roller without problems such as soiling of a photoreceptor or deterioration in energizing durability and with little variance in volume resistivity of a conductive elastic layer due to difference in kneading conditions of rubber material. <P>SOLUTION: The conductive elastic layer is made of rubber composite containing conductive filler. The conductive filler has DBP oil absorbing quantity which is 450ml/100g or more and 600ml/100g or less for 100 mass part of the rubber component, carbon black (A) in which average particle diameter is 60nm or less is 2 mass parts or more and 10 mass parts or less, DBP oil absorbing quantity is 80ml/100g or more and 150ml/100g or less, contains 5 mass parts or more and 40 mass parts or less cabon black (B) in which the average particle diameter is 30nm or more and 60nm or less and plasticizer components is 20 mass parts or less for the rubber component 100 mass part in conductive rubber layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive roller, and more particularly to a conductive roller suitable for a charging roller, a transfer roller, and the like around a photosensitive member such as an electrophotographic copying machine.

  An electrophotographic apparatus such as an electrophotographic copying machine and an electrophotographic printing machine uniformly charges the surface of a photoconductor, and then forms an electrostatic latent image of a print pattern on the surface of the photoconductor, A system is known in which a toner image is formed by adhering toner, transferred onto a recording sheet, and thermally fixed. Among these methods, a corona discharge method is generally used as a charging method on the surface of the photoreceptor. However, the corona discharge method has problems that a large amount of ozone harmful to the human body is generated and it is difficult to downsize the apparatus.

  In recent years, contact charging methods that are easier to miniaturize than corona discharge methods and do not generate ozone toxic to the human body have been studied and put into practical use. In this contact charging method, a conductive elastic roller is brought into contact with the surface of the photosensitive member with a predetermined pressing force, and since the charging member needs to have uniform adhesion with the photosensitive member, appropriate elasticity is required. It is done. Therefore, an elastic layer having rubber elasticity is used for the charging member, and the elastic layer is required to have non-photosensitive material contamination, heat resistance, surface smoothness, and the like.

  However, it may be difficult to satisfy various required characteristics at the same time with a single material, that is, a single layer rubber roller, and a plurality of layers in which the respective functions are shared by the conductive elastic layer and the conductive surface layer. There is also known a method of using a multi-layered roller combining the above and satisfying various required characteristics in a composite manner.

An important characteristic of the charging member is volume resistivity, which requires a conductivity of a semiconductive region of 1 × 10 ⁴ Ω · cm to 1 × 10 ¹⁰ Ω · cm. The range is adjusted by a combination of different volume specific resistances with the conductive surface layer. It is also known that a good image can be obtained by setting the conductive elastic layer to a low volume resistivity and the conductive surface layer to a high volume resistivity. Here, it is desired to adjust the conductive elastic layer to a low volume resistivity region of less than 1 × 10 ⁶ Ω · cm.

  In order to adjust the conductive elastic layer to have a low volume resistivity, a polar rubber such as epichlorohydrin rubber or acrylonitrile-butadiene copolymer rubber is used for the rubber composition of the charging member, and an ionic conductivity imparting agent is added to the rubber. Thus, there is known a method for increasing the ion carrier concentration in the rubber matrix to lower the electric resistance.

So far, a method of containing an organic metal salt such as a Li salt as an ionic conductivity imparting agent in a polar rubber has been studied. In this case, the resistance value as a semiconductive rubber decreases, but the environmental fluctuation of volume resistivity increases, and the organometallic salt is not compatible with polar rubber. Body contamination and energization durability deterioration may occur. In order to solve this problem, a method of using a quaternary ammonium salt (Patent Document 1) or a quaternary phosphonium salt (Patent Document 2) as an ionic conductivity imparting agent has been proposed. In this method, the change in volume resistivity due to environmental conditions is small, and when 10 parts by mass or more is added to 100 parts by mass of the rubber component, the volume resistivity is less than 1 × 10 ⁷ Ω · cm. The problem of oozing out and contaminating the photoreceptor has not been solved.

  As a means for solving such a problem of bleeding due to an ionic conductivity imparting agent, a method is known in which a volume specific resistance is lowered by adding a filler-based conductive filler to a rubber material. In general, conductive carbon black is used as a filler-based conductive filler.

  However, in a conductive roller having a conductive elastic layer using such conductive carbon black, the volume resistivity varies greatly between production lots, and a desired resistance value cannot be stably obtained. In addition, there is a problem that local resistance varies in the conductive roller. These problems are that it is difficult to uniformly disperse carbon black in the rubber material, and the dispersion state of the rubber is affected by slight differences in the amount of carbon black and slight differences in the kneading conditions of the rubber material such as temperature and time. It is caused by subtle differences.

  As a means for reducing the variation in volume resistivity of the conductive elastic layer, a method using carbon black having a low structure and a large particle size instead of a conductive carbon black having a high structure has been proposed (Patent Document 3). However, in the case of this method, the volume resistivity can be controlled relatively easily, but the conductivity is insufficient, and a desired low volume resistivity cannot be obtained. Furthermore, the variation in volume resistivity is insufficient, and it is difficult to stably produce a conductive elastic layer having a desired volume resistivity value.

In addition, a method of reducing variation in volume resistivity by combining strong conductive carbon black and weak conductive carbon black has been proposed (Patent Document 4). However, in this method, any type of carbon black of ISAF, HAF, MAF, and FEF may be used as the weak conductive carbon black. However, when the carbon black of ISAF or HAF is used, the volume resistivity is low. The variation reduction is insufficient. Also, in order to suppress the increase in the hardness of the roller due to the addition of a large amount of weakly conductive carbon black, an oil-extended rubber material in which a large amount of plasticizer is oil-extended is used. The problem of oozing out and causing photoreceptor contamination has not been solved.
JP-A-11-209633 JP 09-101652 A JP 2000-038512 A JP 09-090714 A

  Therefore, the present invention does not cause problems such as contamination of the photoreceptor or deterioration of the durability of current conduction, and there is little variation in the volume resistivity of the conductive elastic layer due to the difference in the kneading conditions of the rubber material. It is an object to provide a roller.

  The said subject is achieved by the following structure.

(1) In a conductive roller having at least one conductive elastic layer on the outer periphery of a conductive shaft, the conductive elastic layer is a rubber composition containing a conductive filler, and the conductive filler is rubber. Containing 100 parts by mass of the component, 2 parts by mass or more and 10 parts by mass or less of the following carbon black (A) and 5 parts by mass or more and 40 parts by mass or less of carbon black (B) are contained in the conductive elastic layer. The conductive roller, wherein the plasticizer component is 20 parts by mass or less with respect to 100 parts by mass of the rubber component of the conductive elastic layer.
(A) Carbon black having a DBP oil absorption of 450 ml / 100 g or more and 600 ml / 100 g or less and an average particle diameter of 60 nm or less.
(B) Carbon black having a DBP oil absorption of 80 ml / 100 g to 150 ml / 100 g and an average particle size of 30 nm to 60 nm.

(2) The conductive elastic layer further comprises carbon black (C) having a DBP oil absorption of 50 ml / 100 g or less and an average particle size of 100 nm or more and 300 nm or less, and 100 parts by mass of a rubber component of the conductive elastic layer. The conductive roller according to (1) above, wherein the conductive roller is contained in an amount of 10 to 60 parts by mass.

(3) The conductive roller according to (1) or (2), wherein the conductive elastic layer is non-foam rubber.

(4) The conductive roller according to any one of (1) to (3) above, wherein the rubber component of the conductive elastic layer is epihalohydrin rubber and / or acrylonitrile-butadiene copolymer rubber.

(5) The conductive roller according to the above (1) to (4), wherein the conductive elastic layer has a micro rubber hardness of 50 to 80.

  According to the present invention, there is no problem such as contamination of the photosensitive member or deterioration of the durability of electric conduction, and the conductive elastic layer has a small variation in volume resistivity due to the difference in the kneading conditions of the rubber material, and can be manufactured stably. Roller can be provided.

  Next, an embodiment of the present invention will be described.

  In the conductive roller of the present invention, at least one conductive elastic layer is formed on the outer periphery of a shaft having at least a surface conductive, and a functional surface layer may be further provided on the surface.

  As the conductive shaft (core metal), for example, a metal such as iron, copper and stainless steel, a carbon dispersion resin, a metal or metal oxide dispersion resin, etc. are used. Any of these may be used. As the conductive shaft in the present invention, a good conductor such as stainless steel, plated iron, brass and conductive plastic, aluminum, copper, iron, or an alloy containing these is preferably used. It may be a metal tube having a thickness of about 0.1 to 1.5 mm or a cylinder.

  The rubber component of the conductive elastic layer is not particularly limited. For example, acrylonitrile-butadiene copolymer rubber, hydrogenated acrylonitrile-butadiene copolymer rubber, styrene-butadiene copolymer rubber, epihalohydrin rubber, ethylene-propylene-diene rubber Silicone rubber, urethane rubber, fluorine rubber, butadiene rubber, acrylic rubber, isoprene rubber, chloroprene rubber, butyl rubber, etc., and acrylonitrile-butadiene copolymer rubber and epihalohydrin rubber are preferred, and acrylonitrile-butadiene copolymer obtained at a low cost is preferable. Polymerized rubber is particularly preferred.

  As the filler-based conductive filler contained in the conductive elastic layer, at least two types of carbon black having different DBP oil absorption and average particle diameter are used, and preferably three types of DBP having different DBP oil absorption and average particle diameter. Carbon black is used.

  As a result, the volume resistivity of the conductive elastic layer is lowered to some extent by the high structure carbon black (A) having a high structure and a small particle size, and the volume resistivity is reduced by the carbon black (B) having a small particle size and a medium structure. It becomes possible to perform subtle control.

  Furthermore, by simultaneously using the carbon black (C) having a large particle size and a low structure, it is easy to reduce the volume resistivity value, and the variation in the volume resistivity of the conductive elastic layer can be reduced.

  When only carbon black (A) is used, the volume resistivity varies greatly due to a slight difference in blending amount or dispersion state, so that a conductive elastic layer having a desired volume resistivity can be stably produced. Difficult to do.

  In addition, when only carbon black (B) is used, it is necessary to add a large amount of carbon black in order to reduce the conductive elastic layer to a desired volume resistivity, and the hardness of the conductive roller becomes too high. There's a problem.

  The carbon black (A) used here is a carbon black having a DBP oil absorption of 450 ml / 100 g or more and 600 ml / 100 g or less and an average particle diameter of 60 nm or less, preferably 50 nm or less. When carbon black having a DBP oil absorption of less than 450 ml / 100 g or an average particle diameter of more than 60 nm is used, conductivity is not sufficiently imparted to the conductive elastic layer, and a desired volume specific resistance value cannot be obtained. If the DBP oil absorption is 600 ml or less, the average particle size is preferably small, but if the DBP oil absorption exceeds 600 ml / 100 g, it is difficult to uniformly disperse. As the carbon black (A), commercially available products include, for example, Ketjen Black EC600JD (trade name).

  The compounding amount of the carbon black (A) is 2 parts by mass or more and 10 parts by mass or less, and preferably 2 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the rubber component of the conductive elastic layer. If the blending amount is less than 2 parts by mass, it is difficult to lower the volume resistivity to a desired value, and if it exceeds 10 parts by mass, the volume resistivity depends on the slight blending amount difference or dispersion state of the carbon black (A). May vary greatly, making it difficult to stably manufacture the conductive roller.

  The carbon black (B) used here is a carbon black having a DBP oil absorption of 80 ml / 100 g or more and 150 ml / 100 g or less and an average particle diameter of 30 nm or more and 60 nm or less. When carbon black having a DBP oil absorption of less than 80 ml / 100 g or an average particle diameter of more than 60 nm is used, the ability to impart conductivity to the conductive elastic layer becomes too low, and the volume resistivity cannot be controlled. When carbon black having a DBP oil absorption of more than 150 ml / 100 g or an average particle size of less than 30 nm is used, the ability to impart conductivity to the conductive elastic layer becomes too high, and a slight amount of carbon black (B) is blended. The volume resistivity varies greatly due to the difference in quantity and the dispersion state, which may make it difficult to stably manufacture the conductive roller. Specific examples of the carbon black (B) include carbon black classified into MAF (medium ab- ration furnace) class and FEF (fast evolving furnace) class.

  The compounding amount of the carbon black (B) is 5 parts by mass or more and 40 parts by mass or less, and preferably 10 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the rubber component of the conductive elastic layer. If the blending amount is less than 5 parts by mass, the ability to impart conductivity to the conductive elastic layer becomes too low, and it is difficult to control the volume resistivity, and if it exceeds 40 parts by mass, the hardness of the conductive elastic layer May become too high.

  The carbon black (C) used together with the carbon blacks (A) and (B) is a carbon black having a DBP oil absorption of 50 ml / 100 g or less and an average particle diameter of 100 nm to 300 nm. When carbon black having a DBP oil absorption of greater than 50 ml / 100 g or an average particle size of less than 100 nm is used, the ability to impart conductivity to the conductive elastic layer becomes too high, resulting in variations in the volume resistivity of the conductive elastic layer. May grow. Moreover, when an average particle diameter exceeds 300 nm, it is difficult to obtain industrially and it is not preferable. Specific examples of the carbon black (C) include carbon blacks classified into FT (Fine Thermal) class and MT (Medium Thermal) class.

  The compounding amount of carbon black (C) is preferably 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component of the conductive elastic layer. If the blending amount is less than 10 parts by mass, the effect of facilitating the decrease in the volume resistivity value is not manifested, and if it exceeds 60 parts by mass, the hardness of the conductive elastic layer may be too high.

  The conductive elastic layer of the present invention may be provided with a plasticizer. In that case, it is essential that the amount is 20 parts by mass or less with respect to 100 parts by mass of the rubber component of the conductive elastic layer. When a plasticizer exceeding 20 parts by mass is blended, it is not preferable to blend the above-mentioned carbon blacks (A) and (B) in the above amounts because the plasticizer oozes out on the surface of the conductive roller.

  Examples of plasticizers that can be used include phthalate ester plasticizers, adipate ester plasticizers, polyester plasticizers, sepadate ester plasticizers, and acrylic polymer plasticizers. These may be used alone or in combination of two or more. Reactive plasticizers are preferred because they do not easily bleed out.

  In addition to the rubber material and carbon black, the conductive elastic layer is provided with a vulcanizing agent and, if necessary, a vulcanization accelerator and a plasticizer. Further, a filler such as calcium carbide, a surfactant, a flame retardant An anti-aging agent, a silane coupling agent and the like are appropriately disposed.

  When the conductive roller of the present invention is used as a charging member or a transfer member in an electrophotographic apparatus such as an electrophotographic copying machine and an electrophotographic printing machine, the conductive roller contacts the surface of a member to be charged or a recording medium while rotating. Therefore, it is necessary to use an elastic roller having an appropriate hardness, and the hardness is preferably 50 to 80 in terms of micro rubber hardness. The micro rubber hardness is easily measured by a micro rubber hardness meter MD-1 (trade name) manufactured by Kobunshi Keiki Co., Ltd.

  Further, in the above roller hardness, it is preferable that the conductive elastic layer is a non-foamed rubber because the compression set of the roller can be reduced.

  A surface layer may be provided on the surface of the conductive elastic layer in the conductive roller of the present invention. The surface layer can be formed by dissolving or dispersing a binder polymer in a solvent and dispersing the conductive filler in the solvent layer on the surface of the elastic layer by a coating method such as dipping, beam coating, roll coater, or spraying. A method of coating, drying and curing is employed.

The surface layer is for preventing the charging member and the photoconductor from being damaged due to concentration of the charging current when defects such as pinholes occur on the photoconductor. 1 × 10 ⁶ Electrical resistance in the range of Ω to 1 × 10 ¹⁰ Ω is required. Generally, binder polymer such as acrylic resin, polyurethane resin, polyamide resin, polyester resin, polyolefin resin, silicone resin, carbon black, graphite, etc. Conductive carbon black, oxides such as titanium oxide and tin oxide; conductive particles obtained by coating the surface of the particles with metals such as Cu and Ag, oxides and metals; LiClO ₄ , KSCN, NaSCN, LiCF ₃ SO _A desired electric resistance value is used by dispersing an appropriate amount of an ionic electrolyte such as ₃ or the like.

  In the conductive roller of the present invention, a predetermined amount of each component constituting the conductive elastic layer is blended and kneaded in a pressure kneader to produce a rubber composition, and then the rubber composition and the conductive shaft (core) Gold) is coextruded using an extruder equipped with a crosshead and then vulcanized. As the vulcanization method, steam vulcanization, oven heating vulcanization, hot air heating, press vulcanization and the like can be used, and other vulcanization methods may be used. Vulcanization conditions are appropriately selected according to the raw rubber used and each component. Usually, the vulcanization temperature is 120 ° C. to 180 ° C., and vulcanization is performed for 20 minutes to 120 minutes, but is not particularly limited. . The surface of the rubber layer is generally ground after vulcanization, but is not particularly limited thereto.

  The charging roller according to the present invention may be provided with functional layers such as an adhesive layer, a diffusion prevention layer, a base layer, and a primer layer in addition to the elastic layer and the surface layer as necessary.

  The conductive roller of the present invention can be used as a charging roller, a developing roller or a transfer roller of an electrophotographic apparatus.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited at all by these examples.

  Table 1 shows the carbon black used in the examples and comparative examples.

The materials used in Examples and Comparative Examples are as follows.
NBR1: Acrylonitrile-butadiene copolymer rubber “Nipol 1042” (trade name, manufactured by Nippon Zeon Co., Ltd.).
NBR2: Oil-extended acrylonitrile-butadiene copolymer rubber “Clinac # 34.38” to which a plasticizer is added in the polymerization stage (trade name, Bayer Co., Ltd., plasticizer amount 1/3).
ZnO: 2 types of zinc oxide (manufactured by Hitech Corporation).
StZn: Zinc stearate “zinc stearate” (trade name, manufactured by NOF Corporation).
Ca: Calcium carbonate “Silver W” (trade name, manufactured by Shiraishi Calcium Co., Ltd.).
Plasticizer: Plasticizer “Polysizer P202” (trade name, manufactured by Dainippon Ink & Chemicals, Inc.).
DM: Vulcanization accelerator “Noxeller DM” (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.).
TS: Vulcanization accelerator “Noxeller TS” (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.).
Vulcanizing agent: Sulfur “Sulfax 200S” (trade name, manufactured by Tsurumi Chemical Co., Ltd.).

Examples 1-7, Comparative Examples 1-9
A predetermined amount of each component other than the vulcanization system shown in Table 2 to Table 4 is blended, and the pressure kneader DS3-10 type (trade name, manufactured by Moriyama Co., Ltd.) is used for 10 minutes, 20 minutes or 30 minutes, the number of revolutions. Kneading was performed at 30 rpm. Next, after kneading a vulcanizing agent, a vulcanization accelerator and a crosslinking agent with a roll, using an extrusion molding machine equipped with a crosshead, a conductive shaft (diameter 6 mm, length 260 mm, chemical nickel-plated iron) And coextrusion molding. Next, after vulcanization at 170 ° C. for 30 minutes in a continuous vulcanization furnace, both ends are cut off and the surface is polished to produce a conductive roller having a conductive rubber layer length of 230 mm and an outer diameter of 14 mm. did.

  The micro rubber hardness and resistance value of the obtained conductive roller were measured as follows. The results are shown in Tables 2 to 4. The relationship between the kneading time (horizontal axis) and resistance (vertical axis) of the conductive roller is shown in FIG.

<Micro rubber hardness>
As for the micro rubber hardness of the roller, using a conductive roller for 20 minutes of kneading, a total of 12 places in the longitudinal direction and 4 places in the circumferential direction can be measured with a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd. The average value thereof was taken as the micro rubber hardness of the conductive roller.

<Resistance value>
In an N / N environment (23 ° C./50% RH), a load of 500 g is applied to both ends of the shaft of the conductive roller before the surface layer is provided, abutting against a 30 mm diameter aluminum drum, and the aluminum drum is rotated. The conductive roller is rotated at a rotation speed of 30 rpm. In this state, a DC voltage of 200 V was applied from the end of the shaft body, the resistance value of the roller for 1 minute was measured, the average value of the maximum value and the minimum value was obtained, and the resistance value of the conductive roller was obtained.

  Furthermore, the conductive roller produced above was provided with a surface layer as described below, and the photoreceptor contamination was evaluated. The results are also shown in Tables 2 to 4.

<Formation of surface layer>
Conductive tin oxide powder “SN-100P” (trade name, manufactured by Ishihara Sangyo Co., Ltd.) 50 parts by mass, 500 parts by mass of a 1% by mass isopropyl alcohol solution of trifluoropropyltrimethoxysilane and an average particle diameter of 0.8 mm 300 parts by weight of glass beads were added and dispersed for 70 hours with a paint shaker. The dispersion was then filtered through a 500 mesh screen to remove the glass beads. The resulting solution was heated in a hot water bath at 100 ° C. while stirring with a Nauta mixer, and the solvent was removed by drying to obtain a surface-treated conductive tin oxide powder whose surface was subjected to silane coupling treatment.

  200 parts by mass of a lactone-modified acrylic polyol “Placcel DC2009” (trade name, manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 500 parts by mass of methyl isobutyl ketone (MIBK) to obtain a solution having a solid content of 20% by mass. 50 parts by mass of the surface-treated conductive tin oxide powder, 0.01 parts by mass of silicone oil “SH-28PA” (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.) and hexa 1.2 parts by mass of fine particle silica (primary particle size: 0.02 μm) surface-treated with methylene disilazane was added, 200 parts by mass of glass beads having a diameter of 0.8 mm were added thereto, and the mixture was dispersed with a paint shaker for 10 hours.

  In this dispersion, 370 parts by mass of isophorone diisocyanate block type isocyanurate type trimer “Vestanat B1370” (trade name, manufactured by Degussa Huls) and hexamethylene diisocyanate isocyanurate type trimer “ 21.5 parts by weight of “Duranate TPA-B80E” (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.) was mixed, stirred for 1 hour with a ball mill, and finally the solution was filtered through a 500 mesh net to obtain a coating material for the surface layer. .

  This surface layer coating was applied to the surface of the conductive roller by the dipping method. After coating at a pulling speed of 400 mm / min and air-drying for 30 minutes, the axial direction of the roller was reversed and coated again at a pulling speed of 400 mm / min, air-dried again for 30 minutes, and then 100 ° C. at 160 ° C. The surface layer was formed on the conductive roller by drying for a minute.

<Evaluation of photoconductor contamination>
The conductive roller provided with the surface layer prepared above was replaced with a charging roller of a cartridge of an electrophotographic image forming apparatus “LBP-2510” (trade name, manufactured by Canon Inc.), and the temperature of 40 ° C. and 95% humidity was changed. Stored for 1 month in the environment. Thereafter, the cartridge was filled with black toner, incorporated into the image forming apparatus “LBP-2510”, a black and white standard pattern was output, and the obtained output image was visually observed and evaluated according to the following criteria.
○: No image defect was observed at all.
X: Image defects that were considered to be contamination of the photoreceptor due to the plasticizer component were observed.

FIG. 1 is a graph showing the kneading time of the rubber material and the resistance value of the obtained conductive roller. In Comparative Examples 1 and 9, the resistance value was too high to be measured (2.0 × 10 ⁸ Ω or more). In Comparative Example 5, the hardness of the conductive elastic layer was out of specification, and in Comparative Examples 7 and 8, image defects due to photoconductor contamination were significant. Absent.

  As shown in FIG. 1, the conductive roller of the present invention has a gradual change in resistance value even when the kneading time of the rubber material changes, and there is a variation in the volume resistivity of the conductive elastic layer due to the difference in the kneading conditions. Small and stable production. In addition, problems such as contamination of the photoconductor and deterioration of the energization durability do not occur.

It is a graph which shows the kneading time of a rubber material, and the fluctuation | variation of the resistance value of an electroconductive roller.

Claims (5)

In the conductive roller having at least one conductive elastic layer on the outer periphery of the conductive shaft body,
The conductive elastic layer is a rubber composition containing a conductive filler,
The conductive filler contains 2 parts by mass or more and 10 parts by mass or less of the following carbon black (A) and 5 parts by mass or more and 40 parts by mass or less of the carbon black (B) with respect to 100 parts by mass of the rubber component.
And the plasticizer component contained in this electroconductive elastic layer is 20 mass parts or less with respect to 100 mass parts of rubber components of an electroconductive elastic layer, The electroconductive roller characterized by the above-mentioned.
(A) Carbon black having a DBP oil absorption of 450 ml / 100 g or more and 600 ml / 100 g or less and an average particle diameter of 60 nm or less.
(B) Carbon black having a DBP oil absorption of 80 ml / 100 g to 150 ml / 100 g and an average particle size of 30 nm to 60 nm.   The conductive elastic layer further contains carbon black (C) having a DBP oil absorption of 50 ml / 100 g or less and an average particle diameter of 100 nm to 300 nm with respect to 100 parts by mass of the rubber component of the conductive elastic layer. The conductive roller according to claim 1, wherein the conductive roller is contained in an amount of 10 to 60 parts by mass.   The conductive roller according to claim 1 or 2, wherein the conductive elastic layer is non-foam rubber.   The conductive roller according to any one of claims 1 to 3, wherein the rubber component of the conductive elastic layer is an epihalohydrin rubber and / or an acrylonitrile-butadiene copolymer rubber.   The conductive elastic layer according to any one of claims 1 to 4, wherein the conductive elastic layer has a micro rubber hardness of 50 to 80.

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