JP2008170878A - Conductive roller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller contributing to formation of images of high quality for a long period of time and an image forming apparatus capable of forming the images of high quality for a long period of time by using the conductive roller. <P>SOLUTION: The conductive roller 1 is equipped with a shaft 2, an elastic layer 3 formed on the outer peripheral surface of the shaft 2, and a coat layer 4 formed on the outer periphery of the elastic layer 4, wherein the coat layer 4 contains a fibrous carbon material and a powdery carbon material having mass ratio to the fibrous carbon material of 5 to 200. The image forming apparatus equipped with the conductive roller 1 as a developing roller and/or charging roller is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive roller and an image forming apparatus. More specifically, the present invention relates to a conductive roller that contributes to forming a high-quality image over a long period of time, and image formation capable of forming a high-quality image over a long period of time. Relates to the device.

  Various image forming apparatuses using an electrophotographic system are employed in printers such as laser printers and video printers, copiers, facsimiles, and multi-function machines thereof. In an image forming apparatus using an electrophotographic system, various conductive rollers having an elastic layer formed on the outer peripheral surface of a shaft body are usually mounted.

  Specifically, for example, as shown in FIG. 4, a plurality of developing units B, C, M, and Y are arranged in the tandem color image forming apparatus, and the developing unit B will be described as an example. A charging roller as an example of charging means 12B for uniformly charging the image carrier 11B, a developing roller as an example of a developer carrier 23B for supplying the charged developer 22B to the image carrier 11B uniformly, and a recording body A fixing roller 31 constituting a fixing unit 30 for fixing the developer image transferred onto the recording medium 16 is mounted. These conductive rollers carry the developer 22B as desired according to electrical characteristics, uniformly charge the contacted body such as the image carrier 11B, and fix the developer 22B as desired. Or it contributes to forming a high quality image by conveying the recording body 16 etc. as desired.

  Therefore, in order to form a high-quality image, the conductive roller needs to have uniform electrical characteristics, and the conventional conductive roller is an elastic layer formed of a composition containing a conductive material. Etc. For example, Patent Document 1 discloses “a conductive member used in an electrophotographic apparatus or an electrostatic recording apparatus, and having an elastic layer made of foam rubber mixed with carbon nanotubes”. Patent Document 2 describes, “In a developing device including a developer carrying member having a cylindrical cross-sectional shape for carrying and transporting a negatively chargeable one-component developer, the developer carrying Describes a developing device characterized in that a coating film containing a polyacrylonitrile-based carbon fiber and a phenol resin is formed on the cylindrical outer peripheral surface of the body. Further, in Patent Document 3, as a method for producing a conductive composition for electrophotographic equipment used for a member for electrophotographic equipment, “(B) below is predispersed in (A) below, then ( A process for kneading A) and (B), comprising: a process for producing a conductive composition for electrophotographic equipment, (A) a liquid polymer, and (B) an electroconductive fibrous filler. Yes.

  However, in general, since the conductive material is difficult to disperse in resin or rubber, and easily aggregates, the elastic layer or the coating of the conductive roller may be simply formed of a composition containing the conductive material. The electrical properties of the resulting elastic layer or coating cannot be adjusted uniformly throughout the elastic layer or coating, and even if this conductive roller is mounted on an image forming apparatus, it can be of high quality as desired. An image may not be formed. In recent image forming apparatuses, high definition images and high printing speeds have been achieved, and in order to form high quality images, the electrical characteristics of the conductive roller are even higher and more uniform than before. It is required to have sex.

  Furthermore, in order to realize a long life cycle of the image forming apparatus, various studies on various members constituting the image forming apparatus have been made, and various rollers mounted on the image forming apparatus are no exception.

JP 2004-101958 A Japanese Patent No. 2909684 JP 2005-62474 A

  The present invention provides a conductive roller that contributes to forming a high-quality image over a long period of time, and an image capable of forming a high-quality image over a long period of time using the conductive roller. An object is to provide a forming apparatus.

As means for solving the problems,
Claim 1 comprises a shaft, an elastic layer formed on the outer peripheral surface of the shaft, and a coat layer formed on the outer peripheral surface of the elastic layer, the coat layer comprising a fibrous carbon material, and A conductive roller comprising a powdered carbon material having a mass ratio of 5 to 200 with respect to the fibrous carbon material,
Claim 2 is the conductive roller according to claim 1, wherein the fibrous carbon material has a fiber diameter of 5 to 200 nm and a fiber length of 1 to 500 µm.
Claim 3 is the conductive roller according to claim 1 or 2, wherein the powdery carbon material has a particle diameter of 20 to 90 nm.
The conductive carbon according to any one of claims 1 to 3, wherein the fibrous carbon material is at least one selected from the group consisting of carbon nanotubes, carbon nanofibers, and vapor grown carbon fibers. Sex roller,
A fifth aspect of the present invention is an image forming apparatus including the conductive roller according to any one of the first to fourth aspects as a developing roller and / or a charging roller.

  Since the coating layer of the conductive roller according to the present invention contains the fibrous carbon material and the powdered carbon material at a predetermined mass ratio, the fibrous carbon material and the powdered carbon material are hardly agglomerated, Is distributed. As a result, the conductive roller according to the present invention can exhibit uniform electrical characteristics and high durability over its axial direction and circumferential direction. Therefore, according to this invention, the electroconductive roller which contributes to forming a high quality image can be provided.

  Further, since the conductive roller according to the present invention can exhibit uniform electrical characteristics and high durability in the axial direction and the circumferential direction, the conductive roller assembly is used as a developing roller and a charging roller in the image forming apparatus. For example, when used as a charging roller, the image carrier can be uniformly charged as desired over a long period of time, and when used as a developing roller, a charged developer can be used for a long time. The image carrier can be supplied uniformly as desired over a period of time, and as a result, it contributes greatly to the formation of high quality images over a long period of time. Therefore, according to the present invention, an image forming apparatus capable of forming a high-quality image over a long period of time can be provided.

  As shown in FIG. 1, a conductive roller according to an embodiment of the present invention includes a shaft body 2, an elastic layer 3, and a coat layer 4. For example, the image forming apparatus shown in FIG. It is arranged.

The conductive roller 1 preferably has an overall electrical resistivity (hereinafter sometimes referred to as an overall electrical resistivity) of 10 ² to 10 ¹⁰ Ω. When the conductive roller 1 has an overall electrical resistivity in the above range, the charging characteristics are excellent. For example, when the conductive roller 1 is used as a developing roller of an image forming apparatus, a developer is desired. The charged developer can be supplied to the image carrier in a desired manner. On the other hand, when the conductive roller 1 is used as a charging roller of the image forming apparatus, Since the image carrier can be uniformly charged, an electrostatic latent image can be formed as desired by the exposure means. From the standpoint of more excellent charging characteristics, the overall electrical resistivity of the conductive roller 1 is more preferably 10 ³ to 10 ⁹ Ω, and particularly preferably 10 ⁴ to 10 ⁸ Ω. The overall electrical resistivity of the conductive roller 1 is adjusted by adjusting the content of a fibrous carbon material or a powdery carbon material contained in the coat layer 4 described later and / or the volume resistivity of the elastic layer 3. , Can be adjusted within the range.

  As shown in FIG. 2, the total electrical resistivity of the conductive roller 1 is determined by using the resistance measuring instrument 100, for example, a product name “R8340A” (manufactured by Advantest Corporation), to place the conductive roller 1 on the electrode plate 101. 500 g of weights 102 are fixed in a suspended state near both ends of the shaft body 2 (positions where the distance from the ends are equal), and the electrode plate 101 is connected to the resistance measuring device 100 and the resistance measuring device. Measurement is performed by connecting 100 electrodes to the shaft body 2 and applying a voltage of 500 V to the electrode plate 101 and the electrodes for 1 second.

  Further, the conductive roller 1 has a ratio of the maximum value of the partial electrical resistivity to the minimum value of the partial electrical resistivity (hereinafter, referred to as a ratio of the partial electrical resistivity) in the plurality of partial electrical resistivity on the outer peripheral surface thereof. Is preferably 100 or less. When the conductive roller 1 has the partial electrical resistivity ratio, the electrical characteristics become uniform over the conductive roller 1, that is, the axial direction and the circumferential direction of the coat layer 4 located on the surface thereof. The conductive roller 1 supports the developer as desired, uniformly charges the contacted body, fixes the developer as desired, and transports the recording body or the like as desired. And a high-quality image can be formed when it is disposed in the image forming apparatus. The ratio of the partial electrical resistivity is more preferably 80 or less, and particularly preferably 70 or less, in that an image with higher quality can be formed. The lower limit of the ratio of the partial electrical resistivity is preferably 1, but in reality it may be about 10. The ratio of the partial electrical resistivity of the conductive roller 1 can be adjusted, for example, in the same manner as the overall electrical resistivity of the conductive roller 1.

As shown in FIG. 3, the partial electrical resistivity of the conductive roller 1 is determined by using a resistance measuring instrument 100, for example, a product name “R8340A” (manufactured by Advantest Corporation), and connecting the conductive roller 1 to the shaft 2. The side surface of the first electrode 104 (made of metal) having a cylindrical shape with an axial length of 4 mm is fixed to 10 g / cm with respect to the coat layer 4 by being sandwiched and fixed by the roller fixing jig 103 from the axial direction of the coating layer 4. ^{2 with} a load of 2 and connecting the second electrode 105 (made of metal) to the outer peripheral surface of the shaft body 2, applying a voltage of 500 V to the first electrode and the second electrode for 1 second, Measured. At this time, a plurality of positions in the axial direction of the coat layer 4, for example, six positions are selected, and a plurality of positions in the circumferential direction of the coat layer 4 at each position, for example, four positions are selected, for a total of 24 positions. It is better to measure the electrical resistivity. The ratio of the partial electrical resistivity can be calculated by dividing the maximum value of the measured values among the partial electrical resistivity measured in this way by the minimum value.

The maximum value and the minimum value of the partial electrical resistivity in the conductive roller 1 may satisfy the ratio of the partial electrical resistivity. For example, the maximum value of the partial electrical resistivity in the conductive roller 1 is Depending on the value, an improvement in pressure resistance can be expected, but it is preferably 1 × 10 ⁵ to 1 × 10 ⁸ Ω in that the image quality may be deteriorated due to excessive charging of the developer. It is particularly preferably 1 × 10 ^{6 to} 5 × 10 ⁷ Ω, and the minimum value of the partial electrical resistivity in the conductive roller 1 may reduce the image density due to insufficient charge amount of the developer. In this respect, 1 × 10 ³ to 1 × 10 ⁶ Ω is preferable, and 1 × 10 ^{4 to} 5 × 10 ⁶ Ω is particularly preferable.

  The conductive roller 1 preferably has a surface roughness Rz of 1 to 15 μm. When the conductive roller 1 has a surface roughness Rz of 1 to 15 μm, for example, when the conductive roller 1 is used as a developing roller, the developer is carried as desired, and the image carrier On the other hand, when the conductive roller 1 is used as a charging roller, the image carrier is charged as desired and further added to the developer and / or developer. The adhesion amount of the external additive can be reduced. The surface roughness Rz is more preferably 2 to 14 μm, and particularly preferably 2 to 13 μm, in that this effect is more excellent. The surface roughness Rz of the conductive roller 1 is in accordance with JIS B 0601-1984 (10-point average roughness), and a surface roughness meter (trade name “590A”, Tokyo Seimitsu Co., Ltd.) equipped with a measuring probe having a tip radius of 2 μm. The conductive roller 1 is set, and the surface roughness is measured at at least three points with a measurement length of 2.4 mm, a cutoff wavelength of 0.8 mm, and a cutoff type Gaussian, and the average value of these is measured as the surface roughness Rz. And

  Further, the conductive roller 1 preferably has a surface roughness Rz ′ after the durability test of 85% or more of the surface roughness Rz. When the surface roughness Rz ′ after the durability test in the conductive roller 1 is within the above range, the surface layer of the conductive roller 1, for example, the coat layer 4 is excellent in wear durability. It can also contribute to the formation of high quality images over a long period of time. The surface roughness Rz ′ after the durability test in the conductive roller 1 is 88% or more of the surface roughness Rz in that it can sufficiently contribute to the formation of a high-quality image over a longer period of time. It is more preferable that it is 92 to 99% of the surface roughness Rz.

  Here, the durability test in the present invention is performed in a state in which the conductive roller 1 is mounted on the image forming apparatus as a charging roller or a developing roller, for example, in an environment of a temperature of 20 ± 5 ° C. and a relative humidity of 50 ± 5%. This test prints 5,000 sheets of% duty images. That is, the surface roughness Rz ′ after the durability test is obtained by measuring the surface roughness Rz of the conductive roller 1 before printing in accordance with the measurement method, and then using the conductive roller 1 as a charging roller or a developing roller. After 5,000 sheets of 5% duty images are printed under specific conditions after being mounted on the forming apparatus, the conductive roller 1 is taken out of the image forming apparatus, and the surface of the coat layer 4 is coated with cotton or the like soaked with alcohol. Lightly wipe off the attached developer, etc., measure the surface roughness Rz ′ of the conductive roller 1 after the durability test in accordance with the measurement method, and divide the measured surface roughness Rz ′ by the surface roughness Rz. And you can ask for it. Note that the 5% duty image is an image of a solid horizontal band pattern with a printing area of 5% with respect to A4 paper.

  The shaft body 2 only needs to have good conductive properties, and is usually a so-called “core” made of iron, aluminum, stainless steel, brass, or the like. Further, the shaft body 2 may be a shaft body that is made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. Furthermore, the shaft body 2 may be a thermoplastic resin or a thermosetting resin. The shaft body may be formed of a conductive resin in which carbon black or metal powder is blended as a conductivity imparting agent. When the shaft body 2 is disposed in the image forming apparatus shown in FIG. 4 or the like, one end of the shaft body 2 is grounded or a bias voltage is applied, for example, the voltage of the image carrier, It performs functions such as charge injection and development of a latent image by conveying developer from the image carrier.

  The elastic layer 3 is formed by curing a rubber composition described later on the outer peripheral surface of the shaft body 2. The elastic layer 3 preferably has a JIS A hardness of 20 to 70. When the elastic layer 3 has a JIS A hardness of 20 to 70, the contact area between the conductive roller 1 and the contacted body can be increased, and the rebound resilience and compression set of the elastic layer 3 can be increased. Is excellent. The JIS A hardness is 30 to 60 in that the contact area between the conductive roller 1 and the contacted body is improved, and the rebound resilience and compression set of the elastic layer 3 can be improved as desired. Is more preferable, and it is especially preferable that it is 35-50. The JIS A hardness can be measured according to JIS K6301.

The elastic layer 3 preferably has a volume resistivity of 10 ¹ to 10 ⁷ Ω · cm (temperature 20 ° C., relative humidity 50%). If the elastic layer 3 has a volume resistivity of 10 ¹ to 10 ⁷ Ω · cm, even if a non-conductive layer is formed on the outer peripheral surface of the elastic layer 3 or the coat layer 4, the conductive layer The charging property of the roller 1 is excellent. For example, when the conductive roller 1 is used as a charging roller, the image carrier can be uniformly charged as desired, and when it is used as a developing roller, Since the developer can be charged as desired, the developer can be carried as desired, and the carried developer can be supplied to the image carrier as desired. The volume resistivity of the elastic layer 3 is more preferably 10 ² to 10 ⁶ Ω · cm, and more preferably 10 ³ to 10 ⁵ Ω · cm, in that the charging property of the conductive roller 1 is further improved. Particularly preferred. The volume resistivity of the elastic layer 3 can be adjusted within the above range by adjusting the content of the conductivity imparting agent contained in the elastic layer 3. The volume resistivity of the elastic layer 3 can be measured by setting the applied voltage to 100 V according to the method specified in JIS K6911.

  The elastic layer 3 can ensure a uniform contact state with the contacted body, or can ensure a uniform contact width (also referred to as a nip width) between the contacted body and the elastic layer 3. Therefore, the thickness is preferably 1 mm or more, and more preferably 5 mm or more. On the other hand, the upper limit of the thickness of the elastic layer 3 is not particularly limited as long as the accuracy of the outer diameter of the elastic layer 3 is not impaired. In general, if the thickness of the elastic layer 3 is excessively increased, the production cost of the elastic layer 3 increases. Therefore, in consideration of practical production costs, the thickness of the elastic layer 3 is preferably 30 mm or less, and more preferably 20 mm or less. The thickness of the elastic layer 3 is appropriately selected according to the hardness of the elastic layer 3, such as JIS A hardness, in order to achieve a desired contact state or a desired nip width.

  The rubber composition forming the elastic layer 3 contains rubber, optionally a conductivity imparting agent, and optionally various additives. Hereinafter, the rubber composition will be described.

  The rubber is not particularly limited. For example, silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene. Examples thereof include rubbers such as rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluororubber. Silicone or silicone-modified rubber is preferable from the viewpoint of excellent heat resistance and charging characteristics. These rubbers may be a liquid type or a millable type, and can be appropriately selected according to the molding method of the elastic layer 3, characteristics required for the elastic layer 3, and the like.

  If desired, the conductivity imparting agent contained in the rubber composition is not particularly limited as long as it has conductivity, and examples thereof include conductive powder and ion conductive materials. More specifically, examples of the conductive powder include carbons for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT in addition to conductive carbon such as ketjen black and acetylene black. In addition, metals such as titanium oxide, zinc oxide, nickel, copper, silver, germanium, and conductive polymers such as metal oxides, polyaniline, polypyrrole, polyacetylene, etc. can be mentioned. Specific examples include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride. If desired, the conductivity imparting agent is added in an appropriate content so that the elastic layer 3 has a desired volume resistivity when used alone or in combination of two or more. When the conductivity imparting agent is contained in the rubber composition, for example, the content of the conductivity imparting agent in the rubber composition can be 2 to 80 parts by mass with respect to 100 parts by mass of the rubber.

  The rubber composition may contain various additives usually contained in various compositions in addition to the rubber and optionally contained conductivity-imparting agents. Examples of the various additives include a chain. Auxiliaries such as extenders and crosslinkers, catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers , Flame retardant improvers, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The rubber composition uses a rubber kneader such as a two-roller, a three-roller, a roll mill, a Banbury mixer, a dough mixer (kneader), etc., and the rubber, a conductivity-imparting agent and various additives that are optionally added. It is obtained by kneading, for example, for several minutes to several hours, preferably 5 minutes to 1 hour, at room temperature or under heating until uniformly mixed.

  The rubber composition may have a viscosity of 5 to 500 Pa · s at 25 ° C., for example, at a temperature of 5 to 200 Pa · s, in that it can be easily and uniformly injected into a molding die. It is particularly good to have a viscosity. The viscosity of the rubber composition can usually be adjusted by the type and / or blending amount of each component contained therein. If necessary, the viscosity can be adjusted with a solvent or the like.

  Examples of the rubber composition that is preferably used include an addition-curable millable conductive silicone rubber composition and an addition-curable liquid conductive silicone rubber composition.

  The addition-curable millable conductive silicone rubber composition is (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) other than those belonging to the component (B). Containing the conductive material.

R _n SiO _{(4-n) / 2} (1)
Here, R is a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different, preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. Yes, n is a positive number from 1.95 to 2.05.

  R is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and a dodecyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl such as a vinyl group, an allyl group, a butenyl group and a hexenyl group. Group, aryl groups such as phenyl and tolyl groups, aralkyl groups such as β-phenylpropyl group, and part or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms or cyano groups A chloromethyl group, a trifluoropropyl group, a cyanoethyl group, etc. are mentioned.

  In the (A) organopolysiloxane, the molecular chain end is preferably blocked with a trimethylsilyl group, a dimethylvinyl group, a dimethylhydroxysilyl group, a trivinylsilyl group or the like. This organopolysiloxane preferably has at least two alkenyl groups in the molecule, and specifically, 0.001 to 5 mol%, particularly 0.01 to 0.5 mol% of alkenyl groups in R. It is preferable to have a vinyl group. In particular, when a platinum catalyst and an organohydrogenpolysiloxane are used in combination as a curing agent described later, an organopolysiloxane having such an alkenyl group is usually used.

  In addition, this organopolysiloxane can be obtained by cohydrolyzing and condensing one or more selected organohalosilanes, or by converting cyclic polysiloxanes such as siloxane trimers or tetramers into alkaline or It can be obtained by ring-opening polymerization using an acidic catalyst. This organopolysiloxane is basically a linear diorganopolysiloxane, but may be partially branched. Further, it may be a mixture of two or more different molecular structures. This organopolysiloxane usually has a viscosity of 100 cSt or more at 25 ° C., preferably 100,000 to 10,000,000 cSt. The organopolysiloxane usually has a degree of polymerization of 100 or more, preferably 3,000 or more, and an upper limit of preferably 100,000, and more preferably 10,000.

The (B) filler is not particularly limited, but a silica-based filler can be used. Examples of the silica-based filler include fumed silica, precipitated silica, etc., and surface-treated silica having a high reinforcing effect, which is surface-treated with a silane coupling agent represented by a general formula RSi (OR ′) _3. System fillers are preferred. Here, R in the general formula is a glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group or the like, and R ′ in the general formula is a methyl group or an ethyl group. . The silane coupling agent represented by the general formula can be easily obtained, for example, as trade names “KBM1003” and “KBE402” manufactured by Shin-Etsu Chemical Co., Ltd. Such a silica-based filler surface-treated with a silane coupling agent can be obtained by treating the surface of the silica-based filler according to a conventional method. In addition, a commercial item may be used for the silica type filler surface-treated with the silane coupling agent. M.M. A trade name “Zeothix 95” manufactured by HUBER Co., Ltd. is available. The compounding amount of the silica-based filler is preferably 11 to 39 parts by mass, particularly preferably 15 to 35 parts by mass with respect to 100 parts by mass of the (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 to 80 μm, and particularly preferably 2 to 40 μm. The average particle diameter of the silica-based filler can be measured as a weight average value (or median diameter) or the like using, for example, a particle size distribution measuring apparatus such as a laser light diffraction method.

  The conductive material (C) is a conductive material that does not belong to the filler (B), and even if it is made of the same material physically and chemically, it is defined as the filler (B) and filled with silica. The conductive material having a different form and state from the material belongs to (C) the conductive material. Such an electroconductive material is an electroconductivity imparting component, for example, the said electroconductivity imparting agent is mentioned, Among these, carbon black is preferable. A conductive material may be used independently or may use 2 or more types together.

  The addition curable type millable conductive silicone rubber composition can contain various compounds as long as the object of the present invention is not impaired, and if necessary. For example, examples of various compounds or additives include a curing agent and fine silica powder.

  Examples of the curing agent include a curing agent obtained by combining a known platinum-based catalyst and an organohydrogenpolysiloxane, and an organic peroxide. As the platinum-based catalyst, a known catalyst can be used, specifically, platinum element simple substance, platinum compound, platinum complex, chloroplatinic acid, chloroplatinic acid alcohol compound, aldehyde compound, ether compound, Examples include complexes with various olefins. The content of the platinum-based catalyst may be an effective amount, that is, a so-called catalytic amount. For example, it is preferably 1 to 2,000 ppm in terms of platinum group metal with respect to (A) the organopolysiloxane.

The organohydrogenpolysiloxane may be linear, branched or cyclic, and the degree of polymerization is preferably 300 or less, and a diorganopolysiloxane having a dimethylhydrosilylsilyl group blocked at the end. , A copolymer having a terminal trimethylsiloxy group and comprising a dimethylsiloxane unit and a methylhydrodienesiloxane unit, a low viscosity fluid comprising a dimethylhydrodienesiloxane unit (H (CH ₃ ) ₂ SiO _1/2 and SiO ₂ unit, 1 , 3,5,7-tetrahydrodiene-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrodiene-1,3,5,7-tetramethylcyclo Examples include tetrasiloxane and 1,5-dihydrodiene-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane. The content of the hydrodiene polysiloxane is preferably used in such a ratio that the hydrogen atom directly bonded to the silicon atom is 50 to 500 mol% with respect to the alkenyl group of the (A) organopolysiloxane.

  Examples of the organic peroxide include di-t-butyl peroxide, alkyl peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and dicumyl peroxide. Organic peroxides such as aralkyl peroxide can be mentioned. The content of the organic peroxide may be an effective amount, and for example, it is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of (A) organopolysiloxane.

The silica fine powder is suitable for obtaining a good elastic layer 3 of the mechanical strength, the BET specific surface area for the purpose ^{10 m} 2 / g or more, preferably fine silica 50 to 400 m ² / g It is preferable to use a powder. Examples of such silica fine powder include fumed silica (dry silica) and precipitated silica (wet silica), and fumed silica is preferred. When silica fine powder is added to the addition-curable millable conductive silicone rubber composition, the content of the silica fine powder is 5 to 100 parts by mass with respect to 100 parts by mass of (A) organopolysiloxane. Is preferable, it is more preferable that it is 5-90 mass parts, and it is especially preferable that it is 10-50 mass parts. If the content is less than 5 parts by mass, the desired reinforcing effect may not be obtained, and if it exceeds 100 parts by mass, the workability may be deteriorated. The average particle diameter of the silica fine powder is preferably 1 to 80 nm, and particularly preferably 5 to 50 nm. The average particle diameter of the silica fine powder can be measured as a weight average value (or median diameter) or the like using, for example, a particle size distribution measuring apparatus such as a laser light diffraction method.

  The addition-curable millable conductive silicone rubber composition may also contain other additives. Other additives include, for example, colorants, heat resistance improvers such as iron octylate, iron oxide, and cerium oxide, acid acceptors, heat conductivity improvers, mold release agents, alkoxysilanes, and the degree of polymerization of organopolysiloxane ( A) Lower dimethylsiloxane oil and silanol, for example, diphenylsilanediol, α, ω-dimethylsiloxanediol, etc. Examples thereof include various carbon functional silanes, and various cured or uncured olefin elastomers that do not inhibit the crosslinking reaction.

The addition-curable liquid conductive silicone rubber composition comprises (D) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (E) bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms; (F) an inorganic filler having an average particle size of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; and (G). An addition-curable liquid conductive silicone rubber composition containing a conductivity imparting agent and (H) an addition reaction catalyst can be mentioned.

  As said (D) organopolysiloxane, the compound shown by the following average compositional formula (2) is suitable.

R ¹ _a SiO _{(4-a) / 2} (2)
Here, R ¹ in the average composition formula (2) is the same or different monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and a is It is a positive number in the range of 1.5 to 2.8, preferably 1.8 to 2.5, more preferably 1.95 to 2.02.

R ¹ represents an alkyl group, an aryl group, an aralkyl group, an alkenyl group, and one of these hydrogen atoms, as exemplified by R of the organopolysiloxane (A) contained in the addition-curable millable conductive silicone rubber composition. Examples include hydrocarbon groups in which part or all are substituted with halogen atoms or cyano groups. At least two of R ¹ are alkenyl groups, particularly vinyl groups, and preferably 90% or more are methyl groups. Specifically, the alkenyl group content in the organopolysiloxane is 1.0 × 10 ^{−6 to} 5.0 × 10 ⁻³ mol / g, particularly 5.0 × 10 ^{−6 to} 1.0 × 10 ^−. It is preferably ³ mol / g.

  The degree of polymerization of the organopolysiloxane may be liquid at room temperature (25 ° C.) (for example, the viscosity at 25 ° C. is 100 to 1,000,000 mPa · s, preferably about 200 to 100,000 mPa · s). The average degree of polymerization is preferably from 100 to 800, particularly preferably from 150 to 600.

  The (E) organohydrogenpolysiloxane is represented by the following average composition formula (3), and is at least 2, preferably 3 or more (usually 3 to 200), more preferably 3 to 100 in one molecule. Those having hydrogen atoms bonded to silicon atoms are preferably used.

R ² _b H _c SiO _{(4-b-c) / 2} (3)
Here, R ² in the average composition formula (3) is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. Further, b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.

  The content of hydrogen atoms (Si—H) bonded to the silicon atoms is preferably 0.001 to 0.017 mol / g, particularly 0.002 to 0.015 mol / g in the organohydrogenpolysiloxane.

Examples of the organohydrogenpolysiloxane (E) include trimethylsiloxy group-capped methylhydrogen polysiloxane at both ends, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, and dimethylhydrogensiloxy group-capped dimethyl at both ends. Polysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane diphenylsiloxane-dimethylsiloxane _copolymers, copolymers consisting of _(CH 3) 2 _{HSiO 1/2} units and _{SiO 4/2} units, and, (C _{3) 2} HSiO _1/2 units and _{SiO 4/2} units and _{(C 6} H ₅₎ copolymers composed of _{SiO 3/2} units and the like.

  The compounding amount of the organohydrogenpolysiloxane (E) is preferably 0.1 to 30 parts by mass, particularly 0.3 to 20 parts by mass with respect to 100 parts by mass of the (D) organopolysiloxane. preferable. (D) The molar ratio of hydrogen atoms bonded to silicon atoms relative to the alkenyl groups of the organopolysiloxane is preferably 0.3 to 5.0, particularly preferably 0.5 to 2.5. .

The (F) inorganic filler is an important component for obtaining low roller permanent set, volume resistivity being stable over time, and sufficient roller durability. The inorganic filler has an average particle size of 1 to 30 μm, preferably 2 to 20 μm, and a bulk density of 0.1 to 0.5 g / cm ³ , preferably 0.15 to 0.45 g / cm ³ . If the average particle size is less than 1 μm, the electrical resistivity may change over time, and if it is greater than 30 μm, the durability of the elastic layer 3 may be reduced. If the bulk density is less than 0.1 g / cm ³ , the compression set may deteriorate and the electrical resistivity may change over time. If it exceeds 0.5 μm, the elastic layer 3 has insufficient strength and is durable. May decrease. The average particle diameter can be determined as a weight average value (or median diameter), for example, using a particle size distribution measuring device such as a laser diffraction method, and the bulk density is a measurement of the apparent specific gravity according to JIS K 6223. It can be determined based on the method.

  Examples of such inorganic fillers include diatomaceous earth, pearlite, mica, calcium carbonate, glass flakes, and hollow fillers, among which diatomaceous earth, pearlite, and foamed pearlite are preferable.

  The blending amount of the inorganic filler is preferably 5 to 100 parts by mass, particularly preferably 10 to 80 parts by mass with respect to 100 parts by mass of (D) organopolysiloxane.

  The said (G) electroconductivity imparting agent is the same as that of the said electroconductivity imparting agent, The compounding quantity can be 2-80 mass parts with respect to 100 mass parts of (D) organopolysiloxane.

  Examples of the (H) addition reaction catalyst include platinum black, platinous chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an olefin, platinum bisacetoacetate, palladium And catalyst based on rhodium and rhodium. The addition amount of the addition reaction catalyst can be a catalytic amount. For example, the amount of platinum group metal is 0.000 relative to the total mass of (D) organopolysiloxane and (E) organohydrogenpolysiloxane. It is preferably 5 to 1,000 ppm, particularly preferably about 1 to 500 ppm.

  This addition curable liquid conductive silicone rubber composition is a low molecular siloxane ester, a silanol, for example, a dispersant such as diphenylsilanediol, an improved heat resistance such as iron oxide, cerium oxide, iron octylate, etc. Agents, various carbon functional silanes that improve adhesion and moldability, halogen compounds that impart flame retardancy, and the like may be included within a range that does not impair the object of the present invention.

  The addition-curable liquid conductive silicone rubber composition preferably has a viscosity of 5 to 500 Pa · s, particularly preferably 10 to 200 Pa · s, at 25 ° C.

  The coat layer 4 is formed on the outer peripheral surface of the elastic layer 3 using a composition to be described later, and is a fibrous carbon material and a powdery carbon material having a mass ratio of 5 to 200 with respect to the fibrous carbon material. contains.

  The fibrous carbon material may be a fibrous carbon material, and examples thereof include carbon nanotubes, carbon nanofibers, vapor grown carbon fibers, polyacrylonitrile (PAN) based carbon fibers, and pitch based carbon fibers.

  The carbon nanotube (CNT) is a carbon hollow tube in which a graphene sheet having a carbon six-membered ring network is rounded into a cylindrical shape, and has a diameter of several nm to 60 nm, for example. There are two types of carbon nanotubes: single-walled nanotubes (SWCNT) formed by curling one graphene sheet and multi-walled nanotubes (MWCNT) in which a number of graphene sheets are stacked in a coaxial cylinder (concentric circle), Depending on the graphene structure, it can be classified into an armchair type, a zigzag type, and a chiral type (spiral type), and any of them can be used in the present invention. Carbon nanotubes are usually produced by an arc discharge method, a laser ablation method, a plasma synthesis method, a carbide decomposition method, a hydrocarbon gas catalytic decomposition method, or the like. In the present invention, the carbon nanotube includes a carbon nanocoil and a carbon nanohorn.

  Carbon nanotubes may be produced as appropriate, or commercially available products may be used. Commercially available carbon nanotubes include, for example, trade name “CarboLex AP-GRADE” (diameter 20 nm, length 3 μm, manufactured by Carborex) and trade name “MRSW” (diameter 1.2 nm, length 10 μm, Materials and Electro Single-walled nanotubes manufactured by Chemical Research Corporation, trade name “CNF-P” (diameter 20-100 nm, length 0.1-1 μm, manufactured by Gemco Co., Ltd.), trade name “MRCMW” (diameter 10 nm, long 30 μm, Materials and Electrochemical Research Corporation), trade name “MRDW” (diameter 3-5 nm, length 5-15 μm, Materials and Electrochemical Research Corporation), trade name “MRCMFILM” (diameter 10 nm) , Long 30μm, Materials and manufactured by Electro Chemical Research Corporation) and trade name "Graphite Fibrils · Grades BN" (diameter 10nm, length 1~10μm, multi-walled nanotubes, and the like, such as manufactured by Haipirion, Catalysis International, Inc.).

  The carbon nanofiber can be used without any particular limitation. The carbon nanofiber is produced in a fibrous form by, for example, a melt spinning method, a gas phase method, or the like. Carbon nanofibers may be produced as appropriate, or commercially available products may be used. Examples of commercially available carbon nanofibers include, for example, a trade name “carbon nanofiber” (diameter 200 to 500 nm, an aspect ratio of 100,000 or more, amorphous, manufactured by Gunei Chemical Industry Co., Ltd.), and a trade name “carbale” (diameter 50 to 200 nm, a length of 10 to 10 μm, manufactured by GSI Creos Co., Ltd.) and the like.

  The vapor-grown carbon fiber (VGCF) is a carbon hollow tube in which a graphene sheet having a carbon six-membered ring network is rounded into a cylindrical shape, and is formally different from the carbon nanotube in that the diameter is about 5 μm or more. It is distinguished. Vapor-grown carbon fiber is usually produced by thermally decomposing hydrocarbon gas using metal fine particles such as iron as a catalyst. Examples of vapor grown carbon fibers include carbon microcoils and the like in addition to those having the same structure as the carbon nanotubes. Vapor-grown carbon fibers may be produced as appropriate, or commercially available products may be used. Examples of commercially available vapor-grown carbon fibers include trade name “VGCF” (fiber diameter 150 nm, fiber length 8 μm, manufactured by Showa Denko KK), trade name “VGCF-H” (fiber diameter 150 nm, fiber length 6 μm, Showa And a trade name “VGCF-S” (fiber diameter 100 nm, fiber length 10 μm, Showa Denko KK).

  The polyacrylonitrile (PAN) -based carbon fiber and the pitch-based carbon fiber are carbon fibers having a diameter of about 5 μm or more, for example, polyacrylonitrile and isotropic pitch are spun as raw materials, infusibilized, and then carbonized, Manufactured. Polyacrylonitrile (PAN) -based carbon fibers and pitch-based carbon fibers may be appropriately produced, and commercially available products may be used. Examples of commercially available polyacrylonitrile (PAN) -based carbon fibers and pitch-based carbon fibers include a trade name “Kureka M-101S” (diameter 14.5 μm, length 0.13 mm, manufactured by Kureha Chemical Co., Ltd.), a trade name “ DIALEAD K223QM ”(diameter 11 μm, 50 μm, manufactured by Mitsubishi Chemical Corporation), and trade name“ DonaCarbo S-241 ”(diameter 13 μm, length 0.13 mm, manufactured by Donac Corporation) and the like.

  The fibrous carbon material may be one of carbon nanotubes, carbon nanofibers, vapor-grown carbon fibers, polyacrylonitrile (PAN) -based carbon fibers, and pitch-based carbon fibers, or two or more of them. Any combination can be used. In the present invention, the fibrous carbon material is at least one selected from the group consisting of the carbon nanotubes, the carbon nanofibers, and the vapor grown carbon fibers, and has good dispersibility and a manufacturing process. It is preferable at the point which can be simplified, and it is especially preferable that it is at least 1 sort (s) selected from the group which consists of the said carbon nanotube and the said carbon nanofiber.

  The fibrous carbon material preferably has a fiber diameter of 5 to 200 nm in that it can be more uniformly dispersed by the coat layer 4 together with the powdery carbon material described later. In addition, the fiber diameter is more preferably 8 to 150 nm, and particularly preferably 10 to 100 nm, from the viewpoint of improving the film strength, that is, durability, of the coat layer 4. The fiber diameter of the fibrous carbon material is an arithmetic average value of a plurality of fiber diameters measured by observing the plurality of fibrous carbon materials with a transmission electron microscope.

  The fibrous carbon material preferably has a fiber length of 1 to 500 μm, and is more evenly dispersed in that it can be more uniformly dispersed by the coat layer 4 together with the powdery carbon material described later. In addition, it is more preferably 2 to 150 μm, and particularly preferably 3 to 100 μm, in view of improving the film strength of the coat layer 4, that is, durability. That is, when the fiber length is less than 1 μm, the film strength of the coat layer 4 decreases, the coat layer 4 is easily worn or damaged, and may have poor durability. On the other hand, when the fiber length exceeds 500 μm. The film strength of the coat layer 4 is strong, the developer is easily destroyed by the coat layer 4, and the developer may be easily fixed to the coat layer 4. The length of the fibrous carbon material is an arithmetic average value of a plurality of lengths measured by observing the plurality of fibrous carbon materials with a transmission electron microscope.

  The powdery carbon material may be fine particles made of at least 90% amorphous carbonaceous material, and examples thereof include carbon black, graphite, and activated carbon. Examples of the carbon black include conductive carbon such as ketjen black and acetylene black, and carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT. Carbon black is produced by, for example, a contact method, a thermal decomposition method (thermal method), an incomplete combustion method (furness method), or the like. As the carbon black, commercially available products may be used. For example, the trade name “Toka Black # 4400” (particle size 38 nm, manufactured by Tokai Carbon Co., Ltd.), the trade name “Seast FM FEF-HS” (particle size 50 nm, Tokai Carbon Co., Ltd.), trade name “Toka Black # 8300F” (particle size 16 nm, manufactured by Tokai Carbon Co., Ltd.), and trade name “Seast SPSRF-LS” (particle size 95 nm, manufactured by Tokai Carbon Co., Ltd.). It is done. The graphite and the activated carbon can be used without particular limitation, and are produced according to a conventional method. A powdery carbon material can be used individually by 1 type or in combination of 2 or more types of these arbitrarily.

  The powdered carbon material may be in the form of powder or particles, but it is less likely to aggregate, is more excellent in dispersibility, and has a particle diameter of 20 to 90 nm in terms of ensuring desired conductivity. It is preferably 25 to 80 nm, more preferably 30 to 70 nm. The particle diameter of the powdery carbon material is an arithmetic average value of a plurality of particle diameters measured by observing the plurality of powdery carbon materials with a transmission electron microscope.

  The mass ratio of the fibrous carbon material and the powdered carbon material in the coat layer 4 is such that the ratio of the mass of the fibrous carbon material to the mass of the fibrous carbon material is 5 to 200. When the mass ratio of the fibrous carbon material to the powdered carbon material is in the above range, the fibrous carbon material having a long axis length is coated by the interaction between the fibrous carbon material and the powdered carbon material. 4, the fibrous carbon materials are not entangled with each other, and are present in the coat layer 4 while maintaining the form thereof. As a result, the conductivity uniformity and the reinforcing effect in the coat layer 4 are obtained. When the coating layer 4 contains the powdered carbon material in the above-described ratio, it intervenes between the fibrous carbon materials, and as a result, prevents the entanglement of the fibrous carbon materials over time, The reinforcing effect in the layer 4 can be exhibited. Therefore, when the mass ratio of the fibrous carbon material and the powdered carbon material coexisting in the coat layer 4 is in the above range, the conductive roller 1 has uniform electric characteristics and high durability over its axial direction and circumferential direction. It can exhibit the sex. The mass ratio of the fibrous carbon material and the powdery carbon material that coexists in the coat layer 4 is 8 to 120 in that uniform electrical characteristics and high durability can be more effectively exhibited. More preferably, it is 10-100.

  The fibrous carbon material may be contained in the coat layer 4 at a ratio that satisfies the above-described mass ratio of the fibrous carbon material and the powdered carbon material, but the resin and / or rubber of the coat layer 4 is 100 parts by mass. The content of 0.01 to 10 parts by mass with respect to the powdery carbon material is preferable because it can be more uniformly dispersed by the coat layer 4. The fibrous carbon material can be dispersed more uniformly by the coat layer 4 and is excellent in the durability of the coat layer 4. It is more preferable that it is contained in a proportion of 1 to 8 parts by mass, and it is particularly preferred that it is contained in a proportion of 0.3 to 5 parts by mass.

  The powdery carbon material may be contained in the coat layer 4 at a ratio satisfying the mass ratio of the fibrous carbon material and the powdered carbon material, but 100 parts by mass of the resin and / or rubber of the coat layer 4 It is preferable that it is contained at a ratio of 1 to 60 parts by mass relative to the fibrous carbon material because it can be more uniformly dispersed by the coat layer 4. The powdery carbon material can be dispersed more uniformly by the coat layer 4 and the durability of the coat layer 4 is 10 to 10 parts by mass with respect to 100 parts by mass of the resin and / or rubber of the coat layer 4. More preferably, it is contained in a proportion of 40 parts by mass, particularly preferably 15 to 35 parts by mass.

  The coat layer 4 preferably has a micro rubber hardness of 50 to 60. If the coat layer 4 has a micro rubber hardness of 50 to 60, the contact area between the conductive roller 1 and the contacted body can be increased, and the rebound resilience and compression set of the coat layer 4 can be increased. Is excellent. The micro rubber hardness is 51 to 59 in that the contact area between the conductive roller 1 and the contacted body is improved, and the rebound resilience and compression set of the coat layer 4 can be improved as desired. Is more preferable, and it is especially preferable that it is 52-58. The micro rubber hardness of the coat layer 4 is the same material as that for forming the coat layer 4, and a plate-like test piece having a thickness of 2 mm is prepared in the same manner as the coat layer 4, and a micro rubber hardness measuring instrument ( The product name “MD-1” (manufactured by Kobunshi Keiki Co., Ltd.) is used, and the arithmetic average value of the plate-like test pieces measured a plurality of times under the condition of the load time of the push needle of 1 second.

  The coat layer 4 preferably has a tear strength of 15 to 30 N / mm. When the coat layer 4 has a tear strength in the above range, even if a minute crack or the like occurs on the surface of the conductive roller 1, that is, the coat layer 4, when used for a long period of time, It is possible to prevent excessive cracks from growing further and to have a hardness and flexibility that does not deteriorate the developer, resulting in the formation of high-quality images over a long period of time. can do. The tear strength of the coat layer 4 is more preferably 18 to 26 N / mm, and particularly preferably 19 to 24 N / mm, in that the effect is further improved. The tear strength of the coat layer 4 is the same as the material forming the coat layer 4, and a test piece having a predetermined dimension is prepared in the same manner as the coat layer 4, in accordance with the method described in JISK6252. Can be measured.

  In general, the coat layer 4 preferably has a layer thickness of 0.1 to 50 μm, and more preferably has a layer thickness of 10 to 20 μm.

  The composition forming the coat layer 4 is a composition containing a resin and / or rubber, a fibrous carbon material, and a powdery carbon material.

  The resin and / or rubber contained in the composition is not particularly limited. For example, silicone, silicone modified resin or silicone modified rubber, polyurethane, acrylic resin or acrylic rubber, fluororesin or fluororubber, nitrile rubber, ethylene propylene Examples thereof include rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, chloroprene rubber, butyl rubber, and epichlorohydrin rubber. Among these, polyurethane is preferable in terms of good adhesiveness, compression set and environmental stability.

  The polyurethane may be a polyurethane obtained by reacting a polyol and a polyisocyanate, or may be a polyurethane preparation component capable of forming a polyurethane. Examples of the polyurethane preparation component include at least one component selected from the group consisting of a mixture of a polyol and a polyisocyanate, and a prepolymer obtained by reacting a polyol and a polyisocyanate.

  The polyol in the mixture of polyol and polyisocyanate may be any of various polyols usually used in the preparation of polyurethane, but at least one polyol selected from polyether polyols and polyester polyols is used as a coating. The layer 4 is preferable in that it is excellent in wear resistance, electrical stability, water resistance and the like. Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various modified products thereof. These mixtures etc. are mentioned. Examples of the polyester polyol include condensed polyester polyols, lactone polyester polyols, polycarbonate polyols, and mixtures thereof obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol. The polyether polyol and polyester polyol may be used singly or in combination of two or more, or a polyether polyol and a polyester polyol may be used in combination. The polyol is preferably a polyester polyol because it is excellent in thermal stability. The polyol preferably has a number average molecular weight of 1000 to 8000, more preferably 1000 to 5000, in view of excellent compatibility with polyisocyanate and the like described later. The number average molecular weight is a molecular weight when converted to standard polystyrene by gel permeation chromatography (GPC).

  The polyisocyanate in the mixture of polyol and polyisocyanate may be any of various polyisocyanates usually used in the preparation of polyurethane, and examples thereof include aliphatic polyisocyanates and aromatic polyisocyanates. The polyisocyanate is preferably an aromatic polyisocyanate in terms of excellent storage stability and easy control of the reaction rate. Examples of the aromatic polyisocyanate include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI), and tolidine diisocyanate (TODI). It is done. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane-1,4-diisocyanate, and hydrogenated MDI.

  In addition to these polyisocyanates, block polyisocyanates in which isocyanate groups are blocked with a blocking agent are preferably used as the polyisocyanate. Block polyisocyanate has high stability at room temperature and has advantages such as easy handling because the blocking agent is released by heating and the isocyanate group is regenerated. In particular, it has an advantage that it reacts stably even in summer when the humidity is high, and can be used in combination with a reagent having an active group having a high reactivity such as an amino group. Examples of the blocking agent include ε-caprolactams, methyl ethyl ketoximes, 3,5-dimethylpyrazoles, alcohols and phenols. Examples of the blocking agent include isocyanates. In this case, the blocked polyisocyanate is a polyisocyanate dimer (polyuretdione). As the blocking agent, any of the above can be used, but ε-caprolactams and methyl ethyl ketoximes are preferred from the viewpoint of excellent compatibility with the solvent.

  The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500.

  The mixing ratio in the mixture of polyol and polyisocyanate is not particularly limited. Usually, hydroxyl group (OH) contained in polyol and isocyanate group contained in polyisocyanate (NCO, isocyanate group that can be liberated in the case of block polyisocyanate) ) Is preferably 0.7 to 1.15 in that the desired degree of crosslinking in the resulting polyurethane can be achieved. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10. From the viewpoint that hydrolysis of polyurethane can be prevented.

  In a mixture of a polyol and a polyisocyanate, the composition contains, in addition to the polyol and the polyisocyanate, auxiliary agents usually used for the reaction between the polyol and the polyisocyanate, such as a chain extender and a crosslinking agent. May be. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The prepolymer and the polyurethane may be any prepolymer and polyurethane obtained by reacting the polyol and the polyisocyanate, and the molecular weight thereof is not particularly limited. The prepolymer and the polyurethane can be obtained by reacting a polyol and a polyisocyanate by the one-shot method or the prepolymer method in the presence of the auxiliary agent, if desired.

  The polyurethane preparation component is preferably a mixture of polyol and polyisocyanate, particularly preferably a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate. That is, the composition particularly preferably contains a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate.

  The fibrous carbon material contained in the composition is the same as the fibrous carbon material in the coating layer 4 described above, and the powdered carbon material contained in the composition is the powder in the coating layer 4 described above. The same as the carbonaceous material.

  The mass ratio between the fibrous carbon material and the powdery carbon material in the composition is the same as the mass ratio in the coat layer 4 described above. The content of the fibrous carbon material in the composition is the same as the content of the fibrous carbon material in the coat layer 4 described above, and the content of the powdered carbon material in the composition is the coat layer described above. 4 is the same as the content of the powdery carbon material.

  In addition to the resin and / or rubber, the fibrous carbon material, and the powdered carbon material, the composition may generally contain various additives contained in the composition. Examples of the various additives include: Auxiliaries such as chain extenders and crosslinkers, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvements Agents, flame retardant improvers, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The composition comprises a resin kneading machine such as a two-roller, three-roller, roll mill, Banbury mixer, dough mixer (kneader), etc., and / or rubber, fibrous carbon material, powdered carbon material, and For example, it can be obtained by kneading at room temperature or under heating for several minutes to several hours, preferably 5 minutes to 1 hour, until various additives are uniformly mixed as desired. Since this composition contains a fibrous carbon material and a powdered carbon material, each component, particularly the fibrous carbon material and the powdered carbon material, can be easily and uniformly mixed into a resin and / or rubber. .

  The composition may have a viscosity of 5 to 500 Pa · s at 25 ° C., for example, and can be easily formed on the outer peripheral surface of the elastic layer 3. It is particularly good to have a viscosity. The viscosity of the composition can usually be adjusted by the type and / or blending amount of each component contained therein. If necessary, the viscosity can be adjusted with a solvent or the like.

  The conductive roller 1 according to the present invention may have another layer between the elastic layer 3 and the coat layer 4. Examples of the other layer include a primer layer that adheres or adheres the elastic layer 3 and the coat layer 4 to each other. Examples of the material for forming the primer layer include alkyd resins, phenol-modified / silicone-modified alkyd resin modified products, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenol resins, polyamide resins, urethanes. Examples thereof include resins and mixtures thereof. Moreover, as a crosslinking agent which hardens and / or bridge | crosslinks these resin, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogen siloxane compound etc. are mentioned, for example. The primer layer is formed with a thickness of 0.1 to 10 μm, for example.

  The conductive roller 1 according to the present invention is manufactured by forming the elastic layer 3 on the outer peripheral surface of the shaft body 2 and further forming the coat layer 4 on the outer peripheral surface of the elastic layer 3.

  First, the shaft body 2 is prepared. For example, the shaft body 2 is prepared in a desired shape by a known method. The shaft body 2 may be coated with a primer before the elastic layer 3 is formed. Although there is no restriction | limiting in particular as a primer apply | coated to the shaft body 2, The resin similar to the material which forms the primer layer which adheres or adheres the said elastic layer 3 and the coating layer 4, and a crosslinking agent are mentioned. The primer is dissolved in a solvent or the like as desired, and is applied to the outer peripheral surface of the shaft body according to a conventional method such as a dipping method or a spray method.

  The elastic layer 3 is formed by heat-curing the rubber composition on the outer peripheral surface of the shaft body 2. For example, the elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The method for curing the rubber composition may be any method that can apply heat necessary for curing the rubber composition, and the molding method for the elastic layer 3 is particularly limited, such as continuous vulcanization by extrusion, pressing, or molding by injection. Is not to be done. For example, when the rubber composition is an addition-curable millable conductive silicone rubber composition, for example, extrusion molding or the like can be selected, and the rubber composition is an addition-curable liquid conductive silicone rubber composition. In this case, for example, a molding method using a mold can be selected. The heating temperature for curing the rubber composition is from 100 to 500 ° C., particularly from 120 to 300 ° C., in the case of an addition-curable millable conductive silicone rubber composition, the time is from several seconds to 1 hour, especially from 10 seconds to It is preferably 35 minutes or less, and in the case of an addition curable liquid conductive silicone rubber composition, it is 100 to 300 ° C., particularly 110 to 200 ° C., and the time is 30 minutes to 5 hours, particularly 1 to 3 hours. Is preferred. In addition, in the case of an addition-curable millable conductive silicone rubber composition, if necessary, the curing conditions are about 100 to 200 ° C. for about 1 to 20 hours, and in the case of an addition-curable liquid conductive silicone rubber composition. Secondary crosslinking may be performed at 120 to 250 ° C. under curing conditions for about 30 to 70 hours. The rubber composition can be foam-cured by a known method to easily form a sponge-like elastic layer having bubbles.

  The elastic layer 3 formed in this way has its surface polished and ground as desired to adjust the outer diameter, surface state, and the like. In particular, when the elastic layer 3 is formed of an addition curable type millable conductive silicone rubber composition, the surface should be polished and ground after the addition curable type millable conductive silicone rubber composition is heat cured. .

  In the elastic layer 3 thus formed, the primer layer may be formed before the coat layer 4 is formed. The primer layer, if necessary, dissolves the material in a solvent or the like, applies the material to the outer peripheral surface of the elastic layer 3 according to a conventional method, for example, a dip method, a spray method, etc. The material is heat cured.

  The coating layer 4 is coated with the composition containing the fibrous carbon material and the powdered carbon material on the outer peripheral surface of the elastic layer 3 thus formed or the primer layer formed as desired, The coated composition is cured by heating. Coating of the composition includes, for example, a coating method in which a coating liquid of the composition is coated, a dipping method in which the elastic layer 3 and the like are immersed in the coating liquid, and spray coating in which the coating liquid is sprayed on the elastic layer 3 and the like It is carried out by a known coating method such as a method. The composition may be applied as it is or volatile to the composition, for example, alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, and ester solvents such as ethyl acetate and butyl acetate. You may apply the coating liquid which added the solvent. This coating liquid is a coating liquid in which the composition is dissolved or suspended, and contains, for example, about 80% by mass of a volatile solvent. The method for heat-curing the composition thus coated may be any method that can apply heat necessary for curing the composition. For example, the elastic layer 3 or the like coated with the composition is heated by a heater. The method of heating with is mentioned. The heating temperature when the composition is heat-cured is, for example, 100 to 200 ° C, particularly 130 to 160 ° C, and the heating time is preferably 10 to 120 minutes, particularly 30 to 60 minutes. In place of the coating, the composition is laminated on the outer peripheral surface of the elastic layer 3 or the primer layer by a known molding method such as extrusion molding, press molding, injection molding or the like, or after the lamination, A method of heating the laminated composition or the like can be employed.

  In the conductive roller 1, the coating layer 4 formed on the outer peripheral surface of the elastic layer 3 contains the fibrous carbon material and the powdered carbon material in a specific mass ratio. The fibrous carbon materials are not entangled with each other due to the interaction with the material, etc., and remain in the coat layer 4 and / or interposed between the fibrous carbon materials for a long time. The fibrous carbon material and the powdery carbon material are uniformly dispersed in the coat layer 4 with almost no aggregation. As a result, the conductive roller 1 can exhibit uniform electrical characteristics and high durability over the axial direction and the circumferential direction. Accordingly, the conductive roller 1 is suitably used for various rollers disposed in the image forming apparatus, in particular, a developing roller, a charging roller, and the like.

  Next, an example of an image forming apparatus (hereinafter sometimes referred to as an image forming apparatus according to the present invention) provided with the conductive roller 1 according to the present invention will be described with reference to FIG. The image forming apparatus shown in FIG. 4 is a direct transfer type tandem color image forming apparatus that directly transfers a developer image developed on an image carrier to a recording medium. A developing roller as a carrier and a charging roller as a charging means are mounted.

  As shown in FIG. 4, the image forming apparatus 10 includes image carriers 11 </ b> B, 11 </ b> C, 11 </ b> M, and 11 </ b> Y equipped in four types of development units B, C, M, and Y arranged in series on the transfer conveyance belt 1. Therefore, the developing units B, C, M, and Y are arranged in series on the transfer conveyance belt 1.

  As shown in FIG. 4, the developing unit B is provided with a rotatable image carrier 11B on which an electrostatic latent image is formed, in contact with or in pressure contact with the image carrier 11B, or at a predetermined interval. The charging means 12B for charging the image carrier 11B, the exposure means 13B provided above the image carrier 11B and forming an electrostatic latent image on the image carrier 11B, and the image carrier 11B are in contact with or pressed against each other. Or developing means 20B for supplying the developer 22B with a constant layer thickness to the image carrier 11B and developing the electrostatic latent image, and a transfer conveyance belt below the image carrier 11B. A transfer unit 14B, which is provided so as to be in contact with or pressed through 1 and transfers the developed electrostatic latent image from the image carrier 11B onto the recording medium 16 conveyed by the transfer conveyance belt 1; Is not transferred to the image carrier 11B and remains on the image carrier 11B. And a cleaning unit 15B for removing the developer 22B, and the like. As shown in FIG. 4, the image carrier 11 </ b> B and the transfer unit 14 </ b> B in the developing unit B are in contact or pressure contact with each other via the transfer conveyance belt 1 stretched around the two support rollers 5. The recording body 16 is transported by the transfer transport belt 1 so as to pass through the contact portion between the image carrier 11B and the transfer unit 14B. The transfer conveyance belt 1 conveys the recording medium 16 and transfers the developed electrostatic latent image on the image carrier 11B in cooperation with the transfer means 14B. As the image carrier 11B, the charging unit 12B, the exposure unit 13B, the transfer unit 14B, and the cleaning unit 15B, conventionally known ones can be appropriately selected and used.

  As shown in FIG. 4, the developing means 20B has an opening at a position facing the image carrier 11B, and a housing 21B for storing the developer 22B and an image carrier at the opening of the housing 21B. A rotatable developer carrier 23B which is provided in contact with or pressed against the body 11B or at a predetermined interval and supplies the developer 22B to the image carrier 11B with a constant layer thickness; and a developer carrier 23B And a developer regulating member 24B that regulates the layer thickness of the developer 22B by contacting or press-contacting the developer carrier 23B and charging the developer 22B by frictional charging. As the developer carrier 23B and the developer regulating member 24B, conventionally known ones can be appropriately selected and used. The developer 22B may be a dry developer or a wet developer as long as it can be charged by friction and can be fixed to the recording medium 16, and may be a non-magnetic developer or a magnetic developer. The developing unit B stores a black developer in the housing 21B.

  As shown in FIG. 4, the developing units C, M, and Y are configured similarly to the developing unit B. The developing units C, M, and Y accommodate a cyan developer 22C, a magenta developer 22M, and a yellow developer 22Y in housings 21C, 21M, and 21Y, respectively.

  As shown in FIG. 4, at the bottom of the image forming apparatus 10, a cassette 41 for stacking and storing a plurality of recording bodies is installed as the recording body 16, and one recording body in the cassette 41 is fed by a paper feed roller or the like. It is sent out one by one and conveyed onto the transfer conveyance belt 1.

  As shown in FIG. 4, a fixing unit 30 for fixing various developers (electrostatic latent images) transferred to the recording body 16 is disposed downstream of the recording body 16 in the conveyance direction in the image forming apparatus 10. . As the fixing unit 30, for example, a heat roller fixing device including a fixing roller capable of generating heat, a heat fixing device such as an oven fixing device, a pressure fixing device including a pressurizing fixing roller, or the like can be used. As shown in FIG. 4, in the image forming apparatus 10, a fixing device including an endless belt 6 is disposed as the fixing unit 30. As shown in the cross section of FIG. 4, the fixing device includes a fixing roller 31 and an endless belt supported in the vicinity of the fixing roller 31 in a casing 34 having an opening 35 through which the recording medium 16 passes. The fixing roller 31 includes a roller 33, an endless belt 6 wound around the fixing roller 31 and the endless belt support roller 33, and a pressure roller 32 disposed to face the fixing roller 31. And the pressure roller 32 are pressure heat fixing devices that are rotatably supported so as to abut or press against each other. The endless belt support roller 33 may be a roller that is normally used in an image forming apparatus. For example, an elastic roller or the like is used. Each of the fixing roller 31, the endless belt support roller 33, and the pressure roller 32 includes a heating body (not shown). The pressure roller 32 causes the endless belt 6 to be moved by a biasing means (not shown) such as a spring. Via the fixing roller 31. By passing the recording medium 16 between the endless belt 6 and the pressure roller 32, the developer 42 (electrostatic latent image) transferred to the recording medium 16 is fixed by being heated simultaneously with the pressing. be able to.

  The image forming apparatus 10 operates as follows. First, the image carrier 11B of the developing unit B is uniformly charged by the charging unit 12B, the image is exposed by the exposure unit 13B, and an electrostatic latent image is formed on the surface of the image carrier 11B. On the other hand, in the developing means 20B, the black developer 22B is regulated to a desired layer thickness and charged as desired by the developer carrier 23B and the developer regulating member 24B. Then, the black developer 22B is supplied from the developer carrier 23B to the image carrier 11B, and the electrostatic latent image formed on the image carrier 11B is developed and visualized as a developer image. Next, the developer image is transferred onto the recording medium 16 conveyed by the transfer conveyance belt 1 between the image carrier 11B and the transfer unit 14B. In this way, the developer image is visualized as a black image on the recording medium 16.

  Next, in the same manner as the developing unit B, the cyan image, the magenta image, and the yellow image are superimposed on the recording medium 16 in which the developer image is visualized as a black image by the developing units C, M, and Y, respectively. The image is visualized.

  Next, the recording body 16 in which the color image is visualized is conveyed to the fixing unit 30 by the conveying unit, and passes through a contact portion or a pressure contact portion between the fixing roller 31 and the pressure roller 32 via the endless belt 6. Occasionally heated and / or pressurized to fix the transferred color image as a permanent image. In this way, a color image can be formed on the recording medium 16.

  According to the image forming apparatus 10, the conductive roller 1 according to the present invention is mounted as a developing roller as the developer carrier 23B, 23C, 23M and 23Y and a charging roller as the charging means 12B, 12C, 12M and 12Y. Therefore, both of the developing roller and the charging roller exhibit uniform electrical characteristics and high durability over the axial direction and the circumferential direction. As a result, the image carriers 11B, 11C, 11M, and 11Y can be uniformly charged as desired over a long period of time, and the charged developers 22B, 22C, 22M, and 22Y can be as desired over a long period of time. And uniformly supplied to the image carriers 11B, 11C, 11M, and 11Y. Therefore, according to the image forming apparatus 10, a high quality image can be formed over a long period of time.

  The image forming apparatus 10 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus 10 is not limited to the electrophotographic system, and is, for example, an electrostatic image forming apparatus. Also good. Further, the image forming apparatus 10 is a tandem type color image forming apparatus in which a plurality of image carriers each having a developing unit for each color are arranged in series on a transfer conveyance belt. Even a monochrome image forming apparatus provided with a developing unit may be a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt. The image forming apparatus 10 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

(Example 1)
An electroless nickel-plated shaft (SUM22, diameter 10 mm, length 275 mm) was washed with toluene, and a silicone primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) on its surface. ) Was applied. The shaft body subjected to the primer treatment was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body.

100 parts by weight of methyl vinyl silicone raw rubber (trade name “KE-78VBS”, manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts by weight of dimethyl silicone raw rubber (trade name “KE-76VBS”, manufactured by Shin-Etsu Chemical Co., Ltd.), and carbon 10 parts by weight of black (trade name “Asahi Thermal”, manufactured by Asahi Carbon Co., Ltd.) and fumed silica-based filler (trade name “AEROSIL OX-50”, average primary particle size 40 nm, bulk density 1.3 g / cm ³ 15 parts by mass of Nippon Aerosil Co., Ltd., 0.5 parts by mass of a platinum-based catalyst (trade name “C-19A”, manufactured by Shin-Etsu Chemical Co., Ltd.), and organohydrogenpolysiloxane (trade name “C-19B”) ”, Manufactured by Shin-Etsu Chemical Co., Ltd.), 2.0 parts by mass, kneaded with a pressure kneader, and addition-curable millable conductive silicone rubber composition It was prepared.

  Next, the shaft body on which the primer layer was formed and the addition-curable millable conductive silicone rubber composition were integrally extracted with a crosshead type extruder and heated at 250 ° C. for 30 minutes using a gear oven. Thereafter, using a gear oven, secondary heating was performed at 200 ° C. for 4 hours, and the mixture was allowed to stand at room temperature for 24 hours. Next, the surface of the elastic layer was polished by a cylindrical grinder so that the formed elastic layer had a diameter of 18 mm.

When the JIS A hardness and volume resistivity (temperature 20 ° C., relative humidity 50%) of the elastic layer thus formed were measured by the above method, the JIS A hardness was 40 and the volume resistivity was 2 × 10. ⁴ Ω · cm.

  Next, a silicone primer (trade name “Primer No. 19”, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the elastic layer. On the surface of the elastic layer coated with the primer, 100 parts by mass of urethane-based paint (trade name “Nipporan 5196”, manufactured by Nippon Polyurethane Co., Ltd.), single-walled carbon nanotubes (trade name “CarboLex AP-GRADE”, Carbolex) 0.13 parts by mass, carbon black (trade name “Toka Black # 4400”, manufactured by Tokai Carbon Co., Ltd.), 25 parts by mass (mass ratio of carbon black to single-walled carbon nanotubes is about 192), and isocyanate crosslinking agent A coating solution of a composition containing 14 parts by mass is applied once by a spray coating method and heated at 150 ° C. for 30 minutes to crosslink and / or cure the primer and the urethane-based paint, resulting in a layer thickness of 10 μm. A coating layer was formed. In this way, a conductive roller was produced.

(Example 2)
A conductive roller was produced in the same manner as in Example 1 except that the content of the single-walled carbon nanotube was changed to 0.25 parts by mass (mass ratio of carbon black to single-walled carbon nanotube of 100).
(Example 3)
A conductive roller was produced in the same manner as in Example 1 except that the content of the single-walled carbon nanotube was changed to 0.5 part by mass (mass ratio of carbon black to single-walled carbon nanotube was 50).
Example 4
A conductive roller was produced in the same manner as in Example 1 except that the content of the single-walled carbon nanotube was changed to 4.5 parts by mass (mass ratio of carbon black to single-walled carbon nanotube was about 5.6). .

(Example 5)
A conductive roller was produced in the same manner as in Example 3 except that the single-walled carbon nanotube was changed to a multi-walled carbon nanotube (trade name “MRCMW”, manufactured by Materials and Electrochemical Research Corporation).
(Example 6)
A conductive roller was produced in the same manner as in Example 3 except that the single-walled carbon nanotube was changed to a multi-walled carbon nanotube (trade name “Graphite Fibrils · Grades BN”, manufactured by Hyperion Catalysis International).
(Example 7)
A conductive roller was produced in the same manner as in Example 3 except that the single-walled carbon nanotube was changed to a carbon nanofiber (trade name “CALVEL”, manufactured by GSI Creos Co., Ltd.).
(Example 8)
0.13 parts by weight of the single-walled carbon nanotubes were mixed with 0.2 parts by weight of the single-walled carbon nanotubes and 0.2 parts by weight of the multi-walled carbon nanotube “MRCMW” (single-walled carbon nanotubes and carbon black with respect to the multi-walled carbon nanotubes). A conductive roller was produced in the same manner as in Example 1 except that the mass ratio was changed to 62.5).
Example 9
Except for changing 25 parts by mass of the carbon black to a mixture of 12.5 parts by mass of the carbon black and 12.5 parts by mass of carbon black (trade name “SEAST FM FEF-HS”, manufactured by Tokai Carbon Co., Ltd.) A conductive roller was produced in the same manner as in Example 3.

(Example 10)
A conductive roller was produced in the same manner as in Example 3 except that the single-walled carbon nanotube was changed to a single-walled carbon nanotube (“MRSW”, manufactured by Materials and Electrochemical Research Corporation).
(Example 11)
A conductive roller was produced in the same manner as in Example 3 except that the single-walled carbon nanotube was changed to carbon nanofiber (trade name “carbon nanofiber”, manufactured by Gunei Chemical Industry Co., Ltd.).

(Example 12)
A conductive roller was produced in the same manner as in Example 3 except that the carbon black was changed to carbon black (trade name “Toka Black # 8300F”, manufactured by Tokai Carbon Co., Ltd.).
(Example 13)
A conductive roller was produced in the same manner as in Example 3 except that the carbon black was changed to carbon black (trade name “SEAST SPSRF-LS”, manufactured by Tokai Carbon Co., Ltd.).

(Comparative Example 1)
A conductive roller was produced in the same manner as in Example 1 except that the single-walled carbon nanotube was not contained.
(Comparative Example 2)
A conductive roller was produced in the same manner as in Example 1 except that the carbon black was not contained and the content of the single-walled carbon nanotube was changed to 25 parts by mass.
(Comparative Example 3)
Example except that 0.13 parts by mass of the single-walled carbon nanotubes were changed to 25 parts by mass of carbon nanofibers (trade name “CALVEL”, manufactured by GSI Creos Co., Ltd.) and the carbon black was not used. In the same manner as in Example 1, a conductive roller was produced.

(Comparative Example 4)
A conductive roller was produced in the same manner as in Example 1 except that the content of the single-walled carbon nanotube was changed to 6 parts by mass (mass ratio of carbon black to single-walled carbon nanotube of 4.2).
(Comparative Example 5)
A conductive roller was produced in the same manner as in Example 1 except that the content of the single-walled carbon nanotubes was changed to 0.1 parts by mass (mass ratio of carbon black to single-walled carbon nanotubes 250).

  In the conductive rollers of Examples 1 to 13 and Comparative Examples 1 to 5 thus produced, the micro rubber hardness of the formed coating layer was measured by the above method. Further, the overall electrical resistivity, the maximum and minimum values of the partial electrical resistivity, the surface roughness Rz and the surface roughness Rz ′ after the durability test of these conductive rollers were measured by the above-described methods, and the partial electrical resistance was measured. The ratio of rates was calculated. The results are shown in Table 1. The durability test for the surface roughness Rz ′ was carried out by using the electrophotographic printer (trade name “Microline 5400”, manufactured by Oki Data Corporation) with the conductive rollers of Examples 1 to 13 and Comparative Examples 1 to 5 as developing rollers. Was carried out in an environment with a temperature of 20 ° C. and a relative humidity of 50%.

  Next, four conductive rollers of Examples 1 to 13 and Comparative Examples 1 to 5 were prepared, and developed in the electrophotographic printer (trade name “Microline 5400”, manufactured by Oki Data Co., Ltd.) shown in FIG. The rollers 24B, 24C, 24M and 24Y were arranged. Note that the developer and developer regulating member attached to the electrophotographic printer were used as the developer and the developer regulating member.

In this electrophotographic printer, print density evaluation, image unevenness evaluation, and fogging evaluation were performed.
(Print density evaluation)
The electrophotographic printer was operated in an environment of a temperature of 20 ° C. and a relative humidity of 50%, and black solid-halftone dot-5% duty-white printing was repeated twice. Next, the electrophotographic printer was operated in an environment of a temperature of 20 ° C. and a relative humidity of 50%, and 5,000 sheets of 5% duty images were printed, and a durability test was performed. After this durability test, black solid-halftone dot-5% duty-white printing was repeated twice. The Macbeth density of the black solid print portion printed before and after the durability test was measured with a Macbeth densitometer, and the print density was evaluated based on the measured Macbeth density. In addition, before and after the durability test, if the Macbeth density of the black solid printing portion is less than 1.3, it can be determined that the printing is defective. The results are shown in Tables 1 and 2.

(Evaluation of image unevenness)
The electrophotographic printer was subjected to black solid images twice in an environment of a temperature of 20 ° C. and a relative humidity of 50%. The occurrence of unevenness such as vertical stripes was visually confirmed on the printed black solid image. “◎” indicates that no black solid image has unevenness, “○” indicates that there is slight unevenness in the black solid print portion, and it is acceptable for practical use. The case where it was possible was marked with “Δ”, and the case where many black solid images were uneven was marked with “X”. The results are shown in Tables 1 and 2.

(Cover evaluation)
The electrophotographic printer was operated in an environment of a temperature of 20 ° C. and a relative humidity of 50%, and black solid-halftone dot-5% duty-white printing was repeated twice. Next, the electrophotographic printer was operated in an environment of a temperature of 20 ° C. and a relative humidity of 50%, and 5,000 sheets of 5% duty images were printed, and a durability test was performed. After this durability test, black solid, halftone dot, 5% duty, white background printing was repeated twice, and the white background in the printed 5% duty image was visually observed to confirm the degree of developer adhesion (fogging). did. “◎” indicates that no developer has adhered to the white background portion, and “○” indicates that the developer has adhered to the white background portion, but there is no practical problem. The case where the developer had adhered to a certain level of practical problems was indicated by “Δ”, and the case where a large amount of developer had adhered on the white background portion was indicated by “X”.

  Similar results were obtained when the addition-curable liquid conductive silicone rubber composition was used in place of the addition-curable millable conductive silicone rubber composition.

FIG. 1 is a perspective view showing an example of a conductive roller. FIG. 2 is an explanatory diagram for explaining a method of measuring the overall electrical resistivity of the conductive elastic layer. FIG. 3 is an explanatory view illustrating a method for measuring the partial electrical resistivity of the conductive elastic layer. FIG. 4 is a schematic view of a tandem color image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive roller 2 Shaft body 3 Elastic layer 4 Coat layer 6 Endless belt 10 Image forming apparatus 11B, 11C, 11M, 11Y Image carrier 12B, 12C, 12M, 12Y Charging means 13B, 13C, 13M, 13Y Exposure means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recorder 20 Developing means 21B, 21C, 21M, 21Y, 34 Housing 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, 23Y Development Agent carrier 24B, 24C, 24M, 24Y Developer regulating member 30 Fixing means 31 Fixing roller 32 Pressure roller 33 Endless belt support roller 35 Opening 41 Cassette 42 Support roller 100 Resistance measuring device 101 Electrode plate 102 Weight 103 Roller fixing Tool 104 First electrode 105 Second electrode B, C, , Y developing unit

Claims (5)

  A shaft body, an elastic layer formed on the outer peripheral surface of the shaft body, and a coat layer formed on the outer peripheral surface of the elastic layer, wherein the coat layer includes a fibrous carbon material and the fibrous carbon A conductive roller comprising a powdery carbon material having a mass ratio of 5 to 200 with respect to the material.   The conductive roller according to claim 1, wherein the fibrous carbon material has a fiber diameter of 5 to 200 nm and a fiber length of 1 to 500 μm.   The conductive roller according to claim 1, wherein the powdery carbon material has a particle diameter of 20 to 90 nm.   The conductive roller according to claim 1, wherein the fibrous carbon material is at least one selected from the group consisting of carbon nanotubes, carbon nanofibers, and vapor grown carbon fibers.   An image forming apparatus comprising the conductive roller according to claim 1 as a developing roller and / or a charging roller.

Images