JP2013067722A - Rubber composition for conductive roller and method for producing the same, and conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a conductive roller, which is capable of keeping environment dependence of a conductive roller caused by variation of usage environment low and is hard to contaminate a photoreceptor and the like, contact components in an image formation device.SOLUTION: The rubber composition composes an elastic layer provided on the outer peripheral surface of a shaft, and includes a polymer component and 1-20 pts.mass of conductive silica relative to the polymer component. The conductive silica is preferably the one obtained by subjecting silica to conductive treatment, and preferably has BET specific surface area of 150 m/g or less. A method for producing such rubber composition includes the steps of: preparing the conductive silica; and mixing the conductive silica with the polymer component.

Description

  The present invention relates to a rubber composition for a conductive roller and a method for producing the same, and also relates to a conductive roller provided with an elastic layer made of the rubber composition for a conductive roller.

  In general, in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, or a facsimile, a transfer roller, a developing roller, a toner supply roller, a charging roller, a cleaning roller, an intermediate transfer roller, Alternatively, a roller (conductive roller) provided with conductivity such as a belt driving roller is used.

  The conductive roller has a basic structure in which the outer peripheral surface of the shaft is covered with an elastic layer. The elastic layer constituting the conductive roller is obtained by adding a conductive agent to a rubber base material such as polyurethane or epichlorohydrin rubber to give a predetermined electric resistance. For this elastic layer, there are known an electronic conductivity type to which a conductive agent such as carbon black is added, an ion conductivity type to which an alkali metal salt such as lithium perchlorate is added, and a hybrid type that combines these. Yes.

  Of these, the electroconductive type has a large electrical resistance value due to the fact that it is very difficult to uniformly disperse carbon black in the polymer and that the blending amount of carbon black is slight. There is a problem that manufacturing stability is lacking due to the change.

  As an ionic conductive type, a mixture of epichlorohydrin rubber and NBR with a mixture of lithium salt and adipic acid added (Patent Document 1), and an ionic liquid containing a cation was added to the rubber. A thing (patent document 2) etc. are known. However, the ion conductive type has an environment dependency and has a problem that the resistance value of the roller fluctuates due to the fluctuation of the environment. The environmental dependency here means that there is a difference of a predetermined value or more between the resistance value of the roller under low temperature and low humidity and the resistance value of the roller under high temperature and high humidity.

  Further, in the case of an ion conductive type, the number of parts to which an ionic conductive agent such as an alkali metal salt is added is limited, and when a large amount of the ionic conductive agent is added, the ionic conductive agent oozes out from the roller and bleeds, There is a problem of polluting.

  As a conductive agent, silica (conductive silica) that has been subjected to conductive treatment is conventionally known (Patent Document 3).

JP 2008-197267 A JP 2003-192845 A International Publication No. 2011/007731

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the environmental dependency of the conductive roller due to a change in use environment, and to make contact parts in an image forming apparatus. It is an object to provide a rubber composition for a conductive roller and a conductive roller that are less likely to contaminate the photosensitive member.

  The rubber composition for conductive rollers according to the present invention constitutes an elastic layer provided on the outer peripheral surface of the shaft, and has a conductivity of 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer component and the polymer component. And silica.

  The polymer component preferably contains 50 parts by mass or more of at least one of nitrile rubber and ethylene propylene rubber in 100 parts by mass of the polymer component, and the total of the content of nitrile rubber and the content of ethylene propylene rubber is 100. More preferably, it is prepared so as to be part by mass.

The conductive silica is not particularly limited as long as the silica is subjected to conductive treatment, and preferably has a BET specific surface area of 150 m ² / g or less. More preferably, the silica is subjected to a hydrophobic treatment.

  It is preferable to further include 1 part by mass or more and 6 parts by mass or less of a foaming agent with respect to 100 parts by mass of the polymer component.

  The conductive roller according to the present invention includes an elastic layer made of the rubber composition for a conductive roller according to the present invention.

  The manufacturing method of the rubber composition for electroconductive rollers which concerns on this invention includes the process of preparing electroconductive silica, and the process of mixing electroconductive silica and a polymer component. The step of preparing the conductive silica preferably includes a step of conducting the conductive treatment on the silica.

  According to the rubber composition for a conductive roller according to the present invention, the environment dependency of the conductive roller due to a change in the use environment can be suppressed to a low level, and it is difficult to contaminate a photoreceptor or the like that is a contact component in the image forming apparatus. .

It is a cross-sectional view of the electroconductive roller which concerns on one Embodiment of this invention. It is a schematic diagram explaining the measuring method of the roller resistance value in an Example and a comparative example.

  Hereinafter, the rubber composition for conductive rollers of the present invention (hereinafter sometimes referred to as “rubber composition”), a method for producing the same, and the conductive roller will be described. In addition, this invention is not limited to the matter shown below.

<Composition of rubber composition>
The rubber composition according to the present invention constitutes an elastic layer provided on the outer peripheral surface of the shaft constituting the conductive roller, and is 1 part by mass or more and 20 parts by mass with respect to 100 parts by mass of the polymer component and the polymer component. Part or less of conductive silica.

<Polymer component>
The polymer component as the rubber component is not particularly limited to the material, and may be a diene rubber or a non-diene rubber. The diene rubber may be, for example, natural rubber, isoprene rubber, butadiene rubber, nitrile rubber (NBR (nitrile butadiene rubber)), or styrene-butadiene rubber. The non-diene rubber may be, for example, ethylene propylene rubber (EPM (ethylene propylene rubber)), butyl rubber, urethane rubber, silicone rubber, or acrylic rubber. Two or more kinds of these rubbers may be mixed and used as the polymer component in the present invention.

  The polymer component in the present invention preferably contains 50 parts by mass or more of at least one of NBR and EPM with respect to 100 parts by mass of the polymer component, and more preferably contains 80 parts by mass or more of at least one of NBR and EPM. More preferably, the polymer component in the present invention is prepared such that the total of the NBR content and the EPM content is 100 parts by mass. Here, “the polymer component in the present invention is prepared so that the sum of the NBR content and the EPM content is 100 parts by mass” means that the polymer component is composed of NBR and EPM. This means that the polymer component does not contain rubber components other than NBR and EPM.

  When the polymer component in this invention contains both NBR and EPM, it is preferable that it is NBR: EPM = 90: 10-10: 90 (mass ratio), More preferably, NBR: EPM = 80: 20- 60:40 (mass ratio). If the mass ratio between NBR and EPM is within the above range, NBR itself exhibits ionic conductivity, so the initial resistance value is low. Therefore, the resistance can be sufficiently reduced by adding a small amount of a conductive agent. In addition, since the polymer component contains EPM, deterioration due to ozone can be reduced.

  NBR is a copolymer of acrylonitrile and 1,3-butadiene. The amount of bound acrylonitrile (acrylonitrile content) is not particularly limited, but may be, for example, 10 to 55%, and preferably 15 to 43%.

  Further, as NBR, carboxyl-modified nitrile rubber copolymerized with methacrylic acid, NBIR in which a part of butadiene is replaced with isoprene, or hydrogenated nitrile rubber in which hydrogen is added to the double bond of the butadiene part may be used. .

  EPM is a copolymer of ethylene and propylene. As EPM, a small amount of diene monomer is introduced into EPM to give a double bond in the main chain (EPDM (ethylene propylene diene terpolymer)). Also good. Here, the diene monomer is not particularly limited, and may be, for example, ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene or the like, and is preferably ethylidene norbornene. The introduction amount of the diene monomer is not particularly limited, but may be 3% by mass to 15% by mass with respect to the EPM, and preferably 5% by mass to 15% by mass with respect to the EPM.

<Conductive silica>
Conductive silica is silica that has been subjected to a conductive treatment, and has a volume resistance value of 10 ⁵ Ωcm or more and 10 ¹² Ωcm or less. Here, the specific method of the conductive treatment is not particularly limited, and for example, there is a method of spraying an ionic liquid onto the surface of silica. The volume resistance value of the conductive silica may be measured by, for example, a method of measuring the resistance value when the conductive silica is pressed and a pressure of 9.8 × 10 ⁶ Pa is applied.

  Here, the ionic liquid means a salt that exists in a liquid state even at room temperature, and is not particularly limited, but may be a quaternary salt, for example. The cation constituting the quaternary salt may be, for example, a quaternary ammonium cation or a quaternary phosphonium cation. The quaternary ammonium cation is not particularly limited, and may be an aliphatic ammonium cation such as tetrapentylammonium cation or an alicyclic ammonium cation such as 1,1-dimethylpyrrolidinium cation. Further, it may be an aromatic ammonium cation containing nitrogen such as 1-methylpyridinium cation. The quaternary phosphonium cation is not particularly limited, and may be tetramethylphosphonium or the like. In each of the quaternary ammonium cation and the quaternary phosphonium cation, the substituents bonded to nitrogen or phosphorus may be different from each other, and at least two of the substituents bonded to nitrogen or phosphorus are the same as each other. It may be.

  The anion constituting the quaternary salt may be, for example, an anion containing an alkylsulfonyl fluoride group, a tetrafluoroborate ion, or a hexafluorophosphate ion.

  The conventional rubber composition contains an ionic conductive agent as a conductive agent. However, since the ionic conductive agent usually has a polar group, it has excellent hygroscopicity. For this reason, when a conductive roller is produced using a rubber composition containing an ionic conductive agent, it is difficult for the obtained conductive roller to keep environmental dependency due to fluctuations in use environment (such as humidity) low. On the other hand, in the conductive silica in the present invention, at least a part of the surface is covered with a film derived from an ionic liquid. Therefore, it is thought that the conductive silica in this invention is inferior to hygroscopicity than an ionic conductive agent, and can provide the rubber composition which is hard to receive the influence of a use environment. Therefore, if the elastic layer of a conductive roller is comprised using the rubber composition which concerns on this invention, the conductive roller by which the environmental dependence by the fluctuation | variation of use environment was restrained low can be provided.

  In addition, when a conventional ionic conductive agent is used, the conductive agent may ooze out on the roller surface under high temperature and high humidity, which easily causes photoconductor contamination. On the other hand, the conductive agent in the present invention is conductive silica, and the ionic liquid and silica are in a bonded state. Therefore, since the conductive agent can be prevented from oozing out from the roller, the photosensitive member is hardly contaminated.

Conductive silica in this invention preferably has a specific surface area of less BET 150m ² / g, and more preferably has a specific surface area of less ^{BET 100m 2 / g, 50m 2} / It is more preferable to have a BET specific surface area of g or less. If the BET specific surface area of the conductive silica is 150 m ² / g or less, the hygroscopicity of the conductive silica can be kept low. Such a conductive silica is obtained by subjecting the silica having a BET specific surface area of 150 m ² / g or less to the above-described conductive treatment, and to the silica having a BET specific surface area of 100 m ² / g or less. It is preferably obtained by performing the above-mentioned conductive treatment, and more preferably obtained by performing the above-mentioned conductive treatment on silica having a BET specific surface area of 50 m ² / g or less.

  The conductive silica in the present invention is preferably produced by subjecting silica to a hydrophobic treatment as well as a conductive treatment. As a result, it is possible to further reduce the hygroscopicity of the conductive silica, and thus it is possible to further reduce the environmental dependency of the conductive roller due to the change in the use environment. The method for the hydrophobic treatment is not particularly limited, and for example, there is a method in which a surface treatment with an ionic liquid is performed in combination with a surface modifier. Here, the surface modifier is not particularly limited, but alkylsilazane compounds such as hexamethyldisilazane, alkylalkoxysilane compounds such as dimethyldimethoxysilane, chlorosilane compounds such as dimethyldichlorosilane, or silicone oil compounds. Any combination of two or more of these may be used.

  In this invention, the compounding quantity of electroconductive silica is 1 to 20 mass parts with respect to 100 mass parts of polymer components, Preferably it is 5 to 15 mass parts, More preferably, it is 10 masses. Part to 15 parts by mass. If the compounding quantity of electroconductive silica is less than 1 mass part, the effect obtained by adding electroconductive silica cannot fully be acquired. Therefore, the conductivity is hardly expressed and the resistance value of the roller is increased. On the other hand, when the compounding amount of the conductive silica exceeds 20 parts by mass, there is a possibility that it is disadvantageous in terms of cost.

<Foaming agent>
The rubber composition according to the present invention preferably contains a foaming agent in addition to the polymer component and the conductive silica. Thereby, a sponge-type conductive roller can be provided.

  Although a foaming agent is not limited to material, It is preferable that it is a chemical foaming agent. Chemical blowing agents are classified into organic and inorganic types. The organic foaming agent may be, for example, an azo compound such as azodicarbonamide, a nitroso compound such as N, N′-dinitrosopentamethylenetetraamine, or a hydrazine derivative such as benzenesulfonyl hydrazide. The inorganic foaming agent may be, for example, sodium bicarbonate (sodium bicarbonate), ammonium bicarbonate, ammonium carbonate, or sodium bicarbonate. Two or more of these foaming agents may be mixed and used as the foaming agent of the present invention.

  Although the compounding quantity of a foaming agent is not specifically limited, What is necessary is just 1 mass part or more with respect to 100 mass parts of rubber compositions, Preferably it is 1 mass part or more and 6 mass parts or less. A rubber composition containing less than 1 part by mass of a foaming agent with respect to 100 parts by mass of the rubber composition may not provide a sufficiently foamed elastic layer. Further, in the rubber composition containing more than 6 parts by mass of the foaming agent with respect to 100 parts by mass of the rubber composition, the vulcanization is insufficient due to inhibition of vulcanization, and therefore, the processability is deteriorated or the resistance value of the roller. The problem of increased environmental dependency is likely to occur.

<Other materials>
The rubber composition according to the present invention may contain at least one material shown below.

<Foaming aid>
When the rubber composition according to the present invention includes a foaming agent, the rubber composition according to the present invention preferably includes a foaming aid. The foaming assistant is, for example, an organic acid assistant such as salicylic acid or a urea assistant. The blending amount of the foaming aid is not particularly limited and may be set as appropriate.

<Vulcanizing agent>
The vulcanizing agent is not limited to the material, but may be any organic peroxide such as sulfur, a sulfur-based organic compound such as tetraalkyltyramium-disulfide, a metal compound such as magnesium oxide, or a peroxyester. These materials may be used alone, or two or more of these materials may be used in combination. Among these, it is preferable to use sulfur or a sulfur-based organic compound in that it is inexpensive and easily available, has excellent vulcanizing action, and has excellent wear resistance. The blending amount of the vulcanizing agent is not particularly limited and may be set as appropriate.

<Vulcanization accelerator>
When the rubber composition according to the present invention includes a vulcanizing agent, the rubber composition according to the present invention preferably includes a vulcanization accelerator. The vulcanization accelerator is not particularly limited to the material, and thiazoles such as dibenzothiazoyl disulfide, sulfenamides such as cyclohexylsulfenamide, thiraums such as tetramethyltylium disulfide, or dimethyldithiocarbamate zinc It may be a dithioate such as a salt. These materials may be used alone, or two or more of these materials may be used in combination. The blending amount of the vulcanization accelerator is not particularly limited and may be set as appropriate.

<Vulcanization acceleration aid>
When the rubber composition according to the present invention includes a vulcanization accelerator, the rubber composition according to the present invention preferably includes a vulcanization acceleration aid. The vulcanization acceleration aid is not particularly limited to the material, and may be a metal oxide such as zinc white, or a fatty acid such as zinc stearate or oleic acid. The blending amount of the vulcanization acceleration aid is not particularly limited and may be set as appropriate.

<Filler>
The filler is not limited to materials, but carbon black, calcium carbonate, magnesium carbonate, clay, cork, talc, zeolite, alumina, mica, graphite, aluminum hydroxide, barium sulfate, aluminum sulfate, dibasic phosphite, Any piece of wood, glass powder, or ceramic powder may be used. These materials may be used alone, or two or more of these materials may be used in combination. The blending amount of the filler is not particularly limited and may be set as appropriate.

  The rubber composition according to the present invention may further contain a processing aid, an anti-aging agent, a reinforcing agent, or a softening agent. The processing aid may be a fatty acid such as oleic acid or a metal oxide such as zinc white. Anti-aging agents may be amines, phenols, imidazoles or the like. The softener may be mineral oil, vegetable oil, or synthetic softener.

<Method for producing rubber composition>
The rubber composition according to the present invention includes a step of preparing conductive silica and a step of mixing conductive silica and a polymer component.

In the step of preparing conductive silica, it is preferable to conduct a conductive treatment on silica having a predetermined BET specific surface area. Here, the silica having a predetermined BET specific surface area is preferably a silica having a BET specific surface area of 150 m ² / g or less, as described in the above <Conductive Silica>, and is 100 m ² / g or less. Silica having a BET specific surface area is more preferable, and silica having a BET specific surface area of 50 m ² / g or less is more preferable. Moreover, the method of an electroconductive process should just be the method described by said <electroconductive silica>.

  In the step of preparing conductive silica, it is more preferable to perform not only conductive treatment but also hydrophobic treatment on silica having a predetermined BET specific surface area. The method of hydrophobic treatment may be any method described in the above <Conductive silica>.

  In the step of mixing the conductive silica and the polymer component, the addition amount of the conductive silica, the filler, and the vulcanizing agent described in the above <conductive silica> is mixed with 100 parts by mass of the polymer component. It ’s fine. At this time, the addition amount of the foaming agent described in the above <foaming agent> may be further mixed with 100 parts by mass of the polymer component, or the foaming aid, the vulcanization accelerator, or the vulcanization acceleration aid. Agents and the like may also be mixed.

<Configuration of conductive roller>
FIG. 1 is a cross-sectional view of a conductive roller according to the present invention. The conductive roller 1 includes a shaft 11 and an elastic layer 12 provided on the outer peripheral surface of the shaft 11. The elastic layer 12 is made of the rubber composition according to the present invention. Therefore, in the conductive roller 1 according to the present invention, it is possible to suppress the environmental dependency due to the change in the use environment, and it is possible to prevent the photoreceptor from being contaminated with the conductive agent (conductive silica).

  If the elastic layer 12 is formed using a rubber composition containing a foaming agent, a sponge-based conductive roller can be provided. On the other hand, if the elastic layer 12 is formed using a rubber composition containing no foaming agent, a solid conductive roller can be provided.

  The conductive roller according to the present invention is not limited to a two-layer structure. For example, in the conductive roller according to the present invention, a resin layer made of fluororesin, silicon resin, urethane resin, acrylic resin, or the like may be formed outside the elastic layer 12. As a result, the frictional resistance or adhesive force on the surface of the conductive roller is reduced, and the toner releasability or cleaning property becomes better. Further, if the electrical resistance values of the elastic layer 12 and the resin layer are close to each other, it is possible to suppress the fluctuation of the electrical resistance value when the thickness of the resin layer is changed. is there.

  In the present invention, a surface treatment that reduces the frictional resistance or adhesive force by carbonizing the surface of the conductive roller by ultraviolet irradiation or the like is also useful. When such surface treatment is performed, the frictional resistance or adhesive force against the photoconductor, transfer belt, toner, cleaning plate or the like is reduced, so that paper contamination or contamination from the conductive roller can be prevented.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Examples 1-19, Comparative Examples 1-6>
<Production of conductive silica I>
An ionic liquid prepared by adding 15 g of ethanol as an organic solvent and diluting to 5 g of an aliphatic amine-based ionic liquid (product number IL-A2 manufactured by Guangei Chemical Industry Co., Ltd.) was prepared. Next, 100 g of silica powder (trade name Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) obtained by a gas phase method having a specific surface area of 50 m ² / g was placed in a reaction vessel. Under a nitrogen atmosphere, the ionic liquid was added to the reaction vessel while stirring silica powder with a rotating blade. Thereafter, these were mixed with stirring at a temperature of 200 ° C. for 60 minutes in a nitrogen atmosphere, and then cooled with cooling water. Thereby, conductive silica I was obtained. Thus, since the conductive silica I was obtained without performing the hydrophobic treatment, the number of silanol groups of the conductive silica I was “small”.

<Production of conductive silica II>
Conductive silica II was obtained according to the above <Manufacture of conductive silica I> except that the ionic liquid was changed to part number IL-A3 manufactured by Guangei Chemical Industry Co., Ltd. Thus, since the conductive silica II was obtained without performing the hydrophobic treatment, the number of silanol groups of the conductive silica II was “small”.

<Production of conductive silica III>
Using an ionic liquid diluted by adding not only 15 g of ethanol but also 20 g of hexamethyldisilazane as a surface modifier to 5 g of an aliphatic amine-based ionic liquid (manufactured by Guangei Chemical Co., Ltd., product number IL-A3) Except for the above, conductive silica III was obtained according to the above <Production of conductive silica II>. As described above, since the conductive silica III is obtained by subjecting the conductive silica II to a hydrophobic treatment, the number of silanol groups of the conductive silica III was “very small”.

<Production of conductive silica IV>
An ionic liquid diluted by adding not only ethanol 15 g but also dimethyl silicone oil 20 g as a surface modifier to 5 g of an aliphatic amine-based ionic liquid (product number IL-A3 manufactured by Guangei Chemical Co., Ltd.) was used. Except for the above, conductive silica IV was obtained according to the above <Production of conductive silica II>. As described above, since the conductive silica IV is obtained by subjecting the conductive silica II to a hydrophobic treatment, the number of silanol groups of the conductive silica IV was “very small”.

<Manufacture of conductive silica V>
According to the above <Production of Conductive Silica I> except that silica powder obtained by a gas phase method having a specific surface area of 150 m ² / g (trade name Aerosil 150, manufactured by Nippon Aerosil Co., Ltd.) was used. Silica V was obtained. Since the specific surface area of the conductive silica V is larger than that of the conductive silica I or the like, the number of silanol groups in the conductive silica V was “slightly large”.

<Measurement of specific surface area of conductive silicas I to V>
The specific surface areas of the conductive silicas I to V were measured according to the BET method.

<Manufacture of rubber composition>
After kneading the polymer components shown in each of Tables 1 to 5 with a kneader, materials other than the polymer components among the materials shown in Tables 1 to 5 were sequentially added to the kneader and kneaded. This obtained the rubber composition which concerns on Examples 1-19 and Comparative Examples 1-6.

<Manufacture of conductive roller>
The obtained rubber composition was extruded into a cylindrical shape. Vapor vulcanization was carried out at 150 ° C. for 50 minutes and inserted into a stainless steel shaft. The rubber surface was ground by a polishing machine to form an elastic layer made of a rubber composition. Thereby, the electroconductive roller which concerns on Examples 1-19 and Comparative Examples 1-6 was obtained. The following performance evaluation was performed on the obtained conductive roller.

<Performance evaluation>
<Measurement of roller resistance value>
FIG. 2 is a schematic diagram for explaining a method of measuring a roller resistance value in Examples and Comparative Examples. As shown in FIG. 2, a conductive roller 32 is brought into contact with a metal roll 31 having a diameter of 30 mm at both ends of 0.5 kg, with a total of 1 kg, and a resistance meter 33 (trade name: R8340A, manufactured by Advantest Corporation) is used. A voltage was applied. The average value of the maximum value and the minimum value of the volume resistance value in the measurement for 10 seconds was defined as the roller resistance value.

<Calculation of environmental fluctuation>
The conductive roller was left in the LL environment (temperature 10 ° C, humidity 15%), NN environment (temperature 22 ° C, humidity 55%), and HH environment (temperature 28 ° C, humidity 85%) for 24 hours or longer. . Then, according to the method described in <Measurement of Roller Resistance Value>, the roller resistance value of the conductive roller was measured. Then, the environmental fluctuation amount was calculated according to (environmental fluctuation amount) = (roller resistance value in LL environment (logΩ)) − (roller resistance value in HH environment (logΩ)).

<Evaluation of environmental dependency>
According to the magnitude of the environmental variation obtained in the above <Calculation of environmental variation>, the environmental dependency of the conductive roller was examined. In Tables 1 to 4, “A1” is written when the environmental fluctuation amount is 1.1 or less, and “B1” is written when the environmental fluctuation amount is greater than 1.1 and 1.3 or less. When the environmental fluctuation amount is larger than 1.3, “C1” is indicated. In Table 5, when the environmental fluctuation amount is 1.3 or less, it is described as “A1”, and when the environmental fluctuation amount is greater than 1.3 and 1.5 or less, it is described as “B1”. When the environmental fluctuation amount is larger than 1.5, “C1” is described. In Table 5, there was no item corresponding to “B1”.

<Photoconductor contamination>
The obtained conductive roller was allowed to stand for one week in an environment where the temperature was 40 ° C. and the humidity was 90% in a state where a load was applied in contact with the photoreceptor. Then, image evaluation was performed using the photoreceptor. In Tables 1 to 5, when an abnormal image such as color loss is not recognized in a portion of the photoconductor where the conductive roller is in contact, “A2” is indicated. When an abnormal image such as color loss is recognized in the contacted portion, “C2” is indicated.

  The results are shown in Tables 1-5.

The annotations in Table 1 to Table 5 are as follows. (Note 1) ECO-X is a terpolymer of epichlorohydrin, ethylene oxide, and allyl glycidyl ether, and (epichlorohydrin): (ethylene oxide): ( (Allyl glycidyl ether) = 40: 56: 4 (molar ratio) (Note 2) ECO-Y is a terpolymer of epichlorohydrin, ethylene oxide and allyl glycidyl ether, and (epichlorohydrin) :( ethylene oxide) ): (Allyl glycidyl ether) = 63: 31: 6 (molar ratio) (Note 3) NBR is “DN401” manufactured by Nippon Zeon Co., Ltd. (Note 4) EPDM is manufactured by Mitsui Chemicals, Inc. (Note 5) CB (carbon black) is “Asahi Thermal” manufactured by Asahi Carbon Co., Ltd. Yes (Note 6) Silica is “AEROSIL 50” manufactured by Nippon Aerosil Co., Ltd. (Note 7) The ionic conductive agent is “IL-A2” manufactured by Guangei Chemical Industry Co., Ltd. (Note 8) Zinc oxide is It is “Zinc Hua Special” made by Shodo Chemical Industry Co., Ltd. (Note 9) Stearic acid is “Fatty Acid SA-200” made by Asahi Denka Co., Ltd. (Note 10) Sulfur is made by Tsurumi Chemical Industry Co., Ltd. "Salfax A" (Note 11) Vulcanization accelerator A is "Accel DM" manufactured by Kawaguchi Chemical Industry Co., Ltd. (Note 12) Vulcanization accelerator B is manufactured by Kawaguchi Chemical Industry Co., Ltd. (Note 13) Vulcanization accelerator C is “Accel DZ” manufactured by Kawaguchi Chemical Co., Ltd. (Note 14) Foaming agent is “Neocelbon # 1000M” (manufactured by Eiwa Kasei Kogyo Co., Ltd.) OBSH foaming agent).

  In Examples 1 to 14, the environment dependency of the conductive roller due to the change in the use environment was suppressed to a low level, and the photoreceptor contamination was also suppressed to a low level. The reason may be that the conductive rollers according to Examples 1 to 14 contain a predetermined amount of conductive silica.

  On the other hand, in Comparative Examples 1 and 2, the environment dependency of the conductive roller due to the change in the use environment could not be suppressed low. This is because the conductive roller in Comparative Examples 1 and 2 does not contain a conductive agent, and the conductivity is expressed only by the ion conductive polymer.

  In the conductive rollers in Comparative Examples 3 to 4, the environmental dependency of the conductive roller due to the change in the use environment was suppressed to a low level, but the photoconductor contamination property could not be suppressed to a low level. The reason for this is that since the ionic conductive agent is contained in the conductive rollers in Comparative Examples 3 to 4, the ionic conductive agent exudes from the conductive roller.

  In particular, when Example 5 and Comparative Example 2 were compared, the roller resistance values in the NN environment were not significantly different, but the amount of environmental variation was greatly different. This shows that it is useful to include a predetermined amount of conductive silica in the rubber composition in order to reduce the amount of environmental fluctuation.

  From the results of Examples 1 to 3 and the results of Examples 4 to 7 and from the results of Examples 8 to 10 and the results of Examples 11 to 14, the rubber composition was obtained regardless of the type of ionic liquid. It can be seen that the amount of environmental fluctuation is reduced if a predetermined amount of conductive silica is included.

  From the results shown in Table 4, it can be seen that the amount of environmental variation decreases if the rubber composition contains a predetermined amount of conductive silica, regardless of the mixing ratio of NBR and EPDM in the polymer component.

  From the results shown in Table 5, it can be seen that also in the sponge-based roller, the amount of environmental variation decreases if the rubber composition contains a predetermined amount of conductive silica.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Conductive roller, 11 Shaft, 12 Elastic layer, 31 Metal roll, 32 Conductive roller, 33 Resistance meter.

Claims (9)

A rubber composition for a conductive roller constituting an elastic layer provided on the outer peripheral surface of the shaft,
A polymer component;
A rubber composition for a conductive roller having 1 to 20 parts by mass of conductive silica with respect to 100 parts by mass of the polymer component.   The rubber composition for a conductive roller according to claim 1, wherein the polymer component contains 50 parts by mass or more of at least one of nitrile rubber and ethylene propylene rubber in 100 parts by mass of the polymer component.   The rubber composition for a conductive roller according to claim 2, wherein the polymer component is prepared so that the total content of the nitrile rubber and the ethylene propylene rubber is 100 parts by mass. The rubber composition for a conductive roller according to any one of claims 1 to 3, wherein the conductive silica is obtained by subjecting silica to a conductive treatment, and has a BET specific surface area of 150 m ² / g or less.   The rubber composition for a conductive roller according to claim 4, wherein the silica is subjected to a hydrophobic treatment.   The rubber composition for a conductive roller according to any one of claims 1 to 5, further comprising 1 part by mass or more and 6 parts by mass or less of a foaming agent with respect to 100 parts by mass of the polymer component.   The electroconductive roller provided with the elastic layer which consists of a rubber composition for electroconductive rollers in any one of Claims 1-6. It is a manufacturing method of the rubber composition for conductive rollers in any one of Claims 1-6,
Preparing the conductive silica;
The manufacturing method of the rubber composition for conductive rollers including the process of mixing the said conductive silica and the said polymer component.   The method for producing a rubber composition for a conductive roller according to claim 8, wherein the step of preparing the conductive silica includes a step of performing a conductive treatment on the silica.

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