JP2009025527A - Method for manufacturing conductive rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a conductive rubber roller with excellent workability, which prevents effusion onto a surface of the conductive rubber roller from occurring, and which can be manufactured by a relatively inexpensive manufacturing process. <P>SOLUTION: The conductive rubber roller has a rubber layer manufactured by penetrating continuously a core metal through a crosshead die of an extruder simultaneously with extrusion of a rubber composition using the extruder, by arranging the rubber composition in layers on an outer circumferential face, and thereafter by being subjected to a vulcanization process under no pressurization. In the method of manufacturing the conductive rubber roller, the rubber composition contains an ethylene-proylene-nonconjugated diene copolymerization rubber, calcium carbonate and liquid rubber. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a conductive rubber roller used for a charging roller, a transfer roller, or the like in an image forming apparatus such as electrophotography.

  Generally, conductive rubber rollers such as a charging roller, a developing roller, and a transfer roller used for electrophotography are manufactured as follows. That is, after extruding a rubber composition kneaded with various raw rubbers added with fillers such as carbon black, vulcanizing agent, vulcanization accelerator, softening agent, etc. into a tube shape, After passing through a vulcanizing process with a vulcanizer (UHF), a core metal is press-fitted therein. Further, in recent years, in order to simplify the process, the rubber composition is disposed on a cored bar that has been previously coated with an adhesive, and is manufactured through a process of simultaneously vulcanizing and bonding on the cored bar. Conductive rubber rollers are also known.

  A conductive rubber roller manufactured through a process of simultaneously vulcanizing and adhering a rubber composition on a metal core is generally manufactured as follows. In other words, using a crosshead extruder, etc., a rubber layer of a rubber composition is continuously disposed on the outer periphery of a core metal coated with an adhesive, and then manufactured through a vulcanization process under no pressure in an electric furnace or the like. Alternatively, it is produced through a vulcanization process under pressure using a mold or the like. The step of continuously placing the rubber composition on the outer periphery of the core metal coated with an adhesive using a crosshead extruder or the like simultaneously extrudes the rubber composition and the core metal. Therefore, when a rubber composition having a large rubber shrinkage at the time of extrusion is used, the adhesion between the core metal and the rubber composition tends to be poor, and the core metal and the rubber composition may not be in close contact with each other.

  In the case where the vulcanization step is performed under pressure using a mold or the like, since the vulcanization is performed under pressure, the adhesion between the rubber composition part and the core metal becomes good. However, there are significant disadvantages in terms of manufacturing costs, such as the need for many molds during mass production and the need for mold maintenance.

  On the other hand, when it is manufactured through a vulcanization process under no pressure in an electric furnace or the like, it can be said to be a relatively inexpensive manufacturing method that is advantageous in manufacturing cost, such as simplifying the manufacturing line. However, if a rubber composition having a large rubber shrinkage during extrusion is used, the adhesion between the core metal and the rubber composition tends to be poor. In other words, it is desired to use a rubber composition having good processability for molding in this relatively inexpensive manufacturing process.

  By the way, it is important that conductive rubber rollers such as a charging roller, a developing roller, and a transfer roller used in electrophotography maintain uniform contact with the photosensitive drum in order to respond to higher speed and higher image quality of the apparatus. ing. It is desirable to make the hardness of the conductive rubber roller as low as possible so that the conductive rubber roller and the photoconductor are sufficiently in contact with each other. In order to achieve low hardness, usually, a softening agent such as oil or plasticizer is added to the rubber composition to lower the hardness.

  However, these oils and softeners such as plasticizers are generally migratory. If these ooze out on the surface of the conductive rubber roller, phenomena such as changing the current value (resistance value) of the conductive rubber roller, contaminating the photoreceptor, or causing toner sticking may occur. is there. It is known that the transition of the softening agent can be avoided by using an outer layer having a low affinity for the softening agent and the softening agent having a significantly different solubility parameter value for the outer layer of the conductive rubber roller. However, this limits the materials that can be used for the outer layer.

Patent Document 1 and Patent Document 2 describe a method for preventing bleeding (bleeding) on the surface of a conductive rubber roller by containing at least one of natural solid rubber and synthetic rubber and liquid rubber. Patent Document 3 contains a main rubber component composed of epichlorohydrin, an ethylene propylene diene terpolymer and acrylonitrile-butadiene rubber, and a sub rubber component composed of a liquid rubber, so that the surface of the conductive rubber roller is exuded. A method for preventing is described. Patent Document 4 describes a method for preventing bleeding of the surface of a conductive rubber roller by using a rubber composition containing an ethylene propylene diene terpolymer and a liquid rubber.
JP-A-5-61345 JP-A-5-61346 JP-A-2005-148467 JP 9-325563 A

  However, in Patent Document 1 and Patent Document 2, since no main rubber component is defined, quality deterioration due to ozone deterioration may not be avoided depending on the main rubber component. In addition, since there is no description about the manufacturing process, when molding by the relatively inexpensive manufacturing process described above, the adhesion between the core metal described above and the rubber composition is likely to be poor, and the core The possibility that problems such as gold and rubber composition not sticking to each other cannot be denied.

  In Patent Document 3, since acrylonitrile-butadiene rubber is included in the rubber component, quality deterioration due to ozone deterioration may not be avoided. Further, since a relatively expensive epichlorohydrin is used as the rubber material, the manufacturing cost tends to increase.

  In Patent Document 4, an ethylene propylene diene terpolymer having low cost and excellent ozone resistance is used, but there is no description in the production process. For this reason, when molding in the inexpensive manufacturing process described above, the adhesion between the cored bar and the rubber composition described above may not be good, and the cored bar and the rubber composition may not be adhered. The possibility that a certain problem will occur cannot be denied.

  An object of the present invention is to provide a method of manufacturing a conductive rubber roller that prevents the occurrence of bleeding on the surface of the conductive rubber roller and can be manufactured by a relatively inexpensive manufacturing process.

According to the present invention, at the same time as the rubber composition is extruded using an extruder, the core metal is continuously passed through the crosshead die of the extruder, and the rubber composition is layered on the outer peripheral surface of the core metal. In the method for producing a conductive rubber roller having a rubber layer produced through a vulcanization process under no pressure after being placed,
There is provided a method for producing a conductive rubber roller, wherein the rubber composition contains an ethylene-propylene-nonconjugated diene copolymer rubber, calcium carbonate and a liquid rubber.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the conductive rubber roller which can prevent the generation | occurrence | production of the seepage to the surface of a conductive rubber roller and can be manufactured with a comparatively cheap manufacturing process is provided.

  Hereinafter, embodiments of the present invention will be described.

  The method for producing the conductive rubber roller includes a method using a mold, a method in which a rubber composition extruded into a tube shape is vulcanized and then press-fitted into a core metal, and a core metal is coated with unvulcanized rubber and then vulcanized. Manufacturing methods and the like. The method of vulcanizing after placing the rubber composition on the core is preferable because it has advantages such as being suitable for downsizing and continuous production lines.

  Among them, a step of arranging the rubber composition in a layered manner on the outer peripheral surface of the core metal is performed, and at this time, the rubber composition is continuously extruded using an extruder, and at the same time, the core metal is continuously extruded. It is preferable to pass through the crosshead die. At this time, an adhesive can be previously applied to the cored bar. Thus, it is preferable to vulcanize the rubber layer after disposing the rubber layer on the outer peripheral surface of the cored bar.

  In addition, when a mold is used in the vulcanization process, it is disadvantageous in terms of operation cost and inferior in continuous productivity. Therefore, from the viewpoint of cost and continuous productivity, it is preferable to perform a vulcanization process under no pressure using an electric furnace or a hot air furnace.

From the above, the following method is optimal as a method for manufacturing a conductive rubber roller that can be manufactured by a relatively inexpensive manufacturing process. That is, at the same time as extruding the rubber composition using an extruder, the core metal is continuously passed through the crosshead die of the extruder, and the rubber composition is arranged in layers on the outer peripheral surface of the core metal. This is a method for producing a conductive rubber roller having a rubber layer through a vulcanization step under no pressure. In the present invention, this conductive rubber roller manufacturing method is employed. In the present invention, a rubber composition containing ethylene-propylene-nonconjugated diene copolymer rubber, calcium carbonate and liquid rubber is used as a raw material for the rubber layer. The reason for using the ethylene-propylene-nonconjugated diene copolymer rubber is that the cost is low, the ozone resistance is excellent, and the manufacturing processability can be easily adjusted. In other types of rubber materials, the individual values of the above three points may be superior to the ethylene-propylene-nonconjugated diene copolymer rubber, but in the balance of three points, the ethylene-propylene-nonconjugated diene copolymer rubber is It is because it is very excellent.

  The reason for containing calcium carbonate is that it is easy to obtain a rubber composition having good processability. When a rubber composition not containing calcium carbonate is used, when the rubber composition and the core metal are extruded at the same time in the extrusion process, the rubber shrinkage during the extrusion increases, and the adhesion between the rubber composition and the core metal becomes poor. It is easy, and the rubber composition may not adhere to the metal core. By containing calcium carbonate, such a phenomenon can be efficiently avoided.

  Although the liquid rubber is not particularly limited, liquid polyisoprene, liquid polybutadiene, or a mixture of both is used because it is compatible with ethylene-propylene-nonconjugated diene copolymer rubber and is relatively inexpensive. It is preferable. Among these, water-added liquid polyisoprene (water-added liquid polyisoprene) is more preferable because of good compatibility with the ethylene-propylene-nonconjugated diene copolymer rubber. Hereinafter, the ethylene-propylene-nonconjugated diene copolymer rubber may simply be abbreviated as a rubber component. Moreover, the mass part shown hereafter is a numerical value when the rubber component contained in the rubber composition is 100 mass parts. However, liquid rubber is not included in the rubber component.

  Further, it is preferable not to use migrating oils and softeners such as plasticizers or to reduce the content as much as possible, more specifically, 10 parts by mass or less.

  When the total amount of the liquid rubber is 20 parts by mass or more and 70 parts by mass or less, it is preferable because it is easy to ensure the hardness and manufacturing processability of the conductive rubber roller without using migrating oil and plasticizer. .

  When the total amount of the liquid rubber is 20 parts by mass or more, it is easy to reduce the hardness of the conductive rubber roller, which is preferable. When the total amount of the liquid rubber is 70 parts by mass or less, when the rubber composition is kneaded, a phenomenon such as the rubber composition sticking to a mixer or roll of a rubber kneading apparatus due to a decrease in rubber viscosity may occur. It is easy and preferable to prevent the occurrence.

  The amount of calcium carbonate is preferably 20 parts by mass or more and 70 parts by mass or less. When the calcium carbonate is 20 parts by mass or more, when the rubber composition and the metal core are extruded simultaneously in the extrusion process, the rubber shrinkage during the extrusion becomes small, and the adhesion between the rubber composition and the metal core tends to be good. preferable. When the calcium carbonate is 70 parts by mass or less, it is easy to improve the compression set, which is preferable in terms of quality. The content of the calcium carbonate is more preferably 30 parts by mass or more and 60 parts by mass or less.

  The average particle diameter of calcium carbonate is preferably 1.0 μm or more and 4.0 μm or less. When the average particle size is 1.0 μm or more, it is easy to prevent the calcium carbonate from aggregating during rubber kneading or extrusion, and to prevent the aggregated calcium carbonate from being generated on the rubber roller surface as a foreign matter. Is easy and preferable. When the average particle size is 4.0 μm or less, it is easy to improve the compression set, which is preferable in terms of quality. The average particle size of calcium carbonate is more preferably 1.3 or more and 3.0 μm or less.

  The Mooney viscosity (JIS K6300-1, 100 ° C., ML1 + 4) measured at 100 ° C. of the ethylene-propylene-nonconjugated diene copolymer rubber is more preferably 15 or more and 90 or less. This is because when the Mooney viscosity is in this category, it is easy to obtain a rubber that is easy to process. If the Mooney viscosity is 15 or more, the rubber will soften and prevent deformation easily by applying a little external pressure when molding the rubber roller in the extrusion process or vulcanization process. As a result, the outer diameter of the rubber roller is stabilized. Is easy. When the Mooney viscosity is 90 or less, the rubber becomes hard and the rubber is easily shrunk when the rubber roller is molded in the extrusion process, and the rubber temperature is not easily increased in the extrusion process. It is easy to suppress and is preferable.

  As the contents of calcium carbonate and liquid rubber in the rubber composition increase, the compression set of the resulting rubber layer tends to be inferior. On the contrary, the compression set tends to be superior as the diene content of the ethylene-propylene-nonconjugated diene copolymer rubber is larger. Therefore, the diene content of the ethylene-propylene-nonconjugated diene copolymer rubber is more preferably 8% by mass or more and 15% by mass or less. When the diene content is 8% by mass or more, it is easy to improve the compression set, which is preferable in terms of quality. When the diene content is 15% by mass or less, it is preferable because it is easy to prevent vulcanization from being accelerated and to prevent scorching from being easily performed.

  Conductive carbon black such as Ketjen Black, SAF, ISAF, HAF, MAF, FEF, GPF, SRF, FT, MT, etc. Various conductive agents other than black; clays, magnesium carbonate, silica, magnesium silicate, talc and other fillers; vulcanization accelerators such as zinc white and stearic acid; scorch inhibitor, tackifier, and other rubber additives An agent can be appropriately added to the rubber composition as long as the effects of the present invention are not impaired. In the present invention, since a nonpolar ethylene-propylene-nonconjugated diene copolymer rubber is used, it is preferable to use various conductive agents in order to impart conductivity. As the conductive agent, it is more preferable to use carbon black which hardly causes bleeding (bleed) to the rubber roller surface regardless of the content. The conductivity of the conductive rubber roller is not particularly limited, but the volume resistivity is more preferably in the range of 10 2 to 10 Ω · cm at an applied voltage of 50V.

  The carbon black content is preferably 10 parts by mass or more and 80 parts by mass or less because a conductive rubber roller having a desired electric resistance is easily obtained.

  As the vulcanization form, either peroxide or sulfur-based vulcanization can be used, but sulfur-based vulcanization is more preferable than peroxide vulcanization with many process restrictions. In addition, both foamed rubber foamed using solid rubber or a foaming agent can be used without any problem.

  Various foaming agents can be used for the foamed rubber, but it is more preferable to use an organic foaming agent because of easy control of the degree of foaming.

  In the conductive rubber roller of the present invention, one or more functional layers may be provided on the outer peripheral surface of the rubber layer for the purpose of further improving the surface smoothness, adjusting the resistance, and protecting. As the functional layer, a conductive functional layer that imparts conductivity is often used. For example, a tube layer made of rubber or resin, a conductive layer made by coating, or the like may be formed as a resistance adjustment layer on the outer peripheral surface of the rubber layer. Among them, it is preferable to use a seamless tube containing a thermoplastic elastomer as the outermost layer because of good surface smoothness and easy resistance adjustment.

  According to the present invention, the rubber layer comprises a rubber composition containing ethylene-propylene-nonconjugated diene copolymer rubber, calcium carbonate and liquid rubber, and is manufactured at an inexpensive manufacturing process. A method for manufacturing a conductive rubber roller is possible. Further, it is possible to prevent the surface of the conductive rubber roller from oozing out due to a migratory oil and a softening agent such as a plasticizer. For this reason, the phenomenon that the current value (resistance value) of the conductive rubber roller is changed, the photosensitive member is contaminated, and the toner is fixed is not generated.

  This conductive rubber roller can be used as a member of an electrophotographic apparatus or an electrostatic recording apparatus, and has a very high industrial value.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. The characteristics of the conductive rubber roller obtained in each example were measured according to the following method.

[Extrudability]
After the rubber was extruded at the same time as the core with a crosshead extruder, the adhesion between the rubber and the core and the state of the rubber surface were visually confirmed. The case where there was no problem in adhesion and the rubber surface was good with no rough skin was marked with ◯, and the rubber was shrunk, and the case where the adhesion between the metal core and rubber was not good was marked with x.

[Conductive rubber roller hardness]
The hardness of the obtained conductive rubber roller was measured using a micro rubber hardness meter MD-1 type (trade name) manufactured by Kobunshi Keiki Co., Ltd. This measuring method is based on the type A durometer defined in JISK6253 in principle. The push needle is pressed against the surface of the sample with the force of the spring to deform it, and the hardness is measured based on the push depth of the push needle when the resistance force of the sample and the force of the spring are balanced.

〔Compression set〕
In the permanent strain test method of vulcanized rubber and thermoplastic rubber described in JIS K6262, the measurement was performed at a temperature of 70 ° C., a time of 24 hours, and a compression rate of 25%. All of the test vulcanized rubbers were obtained by press vulcanizing the rubber composition at 160 ° C. for 30 minutes.

[Current change rate]
The current value is applied to an aluminum drum having an outer diameter of 30 mm so that a load of 500 g (4.9 N) is applied to both ends of the shaft body of the conductive rubber roller and a total load of 1 kg (9.8 N) is applied to the core metal. The measurement was performed with the conductive rubber roller pressed. In this state, a current value when a voltage of 200 V was applied between the shaft body and the aluminum drum was adopted. After molding the conductive rubber roller, it is stored in an environment of a temperature of 23 ± 3 ° C. and a relative humidity of 50 ± 5% for one day, and a value obtained by measuring a current value 30 minutes after taking out from the storage environment is defined as a normal current value. Conductive rubber roller with normal current value measured is stored for 1 month in an environment of temperature 40 ± 3 ° C and relative humidity 90 ± 5%, and the current value measured 30 minutes after taking out from this storage environment is stored severely The current value. The current change rate is represented by (normal current value−severe storage current value) divided by the normal current value multiplied by 100, and the smaller this value, the smaller the current value change, that is, the smaller the resistance change due to the severe environment.

[Bleed]
Before the conductive functional layer is formed on the outer circumference of the rubber layer, the rubber roller with only the rubber layer is stored in an environment with a temperature of 40 ± 3 ° C and a relative humidity of 90 ± 5% for one month (hereinafter referred to as harsh environment storage) After that, the presence or absence of bleed on the rubber roller surface was confirmed. In the evaluation of bleed, the surface of the rubber roller due to the influence of bleed was evaluated as ○ where there was no difference in color and gloss by visual judgment before and after severe storage, and the case where the difference was confirmed was evaluated as x.

[Example 1]
-100 mass parts of ethylene-propylene-nonconjugated diene copolymer rubber (EPDM-1).
[Product Name: EPT4070, manufactured by Mitsui Chemicals, Mooney viscosity (100 ° C., ML1 + 4) is 69, diene content is 10.6% by mass].
-5 parts by mass of zinc oxide.
[Product name: Zinc flower, 2 types, manufactured by Hakusui Tec Co., Ltd.].
-1 part by mass of stearic acid.
[Product Name: LUNAC S-20, manufactured by Kao Corporation].
-50 mass parts of calcium carbonate.
[Product name: Super SS, manufactured by Maruo Calcium Co., Ltd., average particle size 2.2 μm].
-Liquid polyisoprene-1 50 mass parts.
[Product name: LIR-290 (water-added liquid polyisoprene), manufactured by Kuraray Co., Ltd.].
-Carbon black 80 mass parts.
[Product name: Asahi # 70, manufactured by Asahi Carbon Co., Ltd.].
-Morpholinodithio compound (MDB) 2 parts by mass.
[Product name: Noxeller MDB, manufactured by Ouchi Shinko Chemical Co., Ltd.].
-2-Mercaptobenzothiazole (MBT) 2 mass parts.
[Product name: Noxeller M, manufactured by Ouchi Shinko Chemical Co., Ltd.]
-2 parts by mass of dipentamethylene thiuram tetrasulfide (DPTT).
[Product name: Noxeller TRA, manufactured by Ouchi Shinko Chemical Co., Ltd.]
・ Sulfur 2 parts by mass.

  The above components were kneaded with a pressure kneader to produce a rubber composition. The above rubber composition was extruded using a φ40 mm crosshead extruder, and simultaneously a hot melt adhesive [trade name: ThreeBond 3315E, manufactured by ThreeBond Co., Ltd.] was applied to a core of φ6 mm, length 250 mm Gold was passed through the extruder crosshead die. In the present specification, φ means a diameter. In this way, after placing the rubber composition on the outer periphery of the core metal to form a roller, it is placed in a hot air oven for 30 minutes at 200 ° C. and vulcanized without pressure, and on the outer periphery of the core metal An unground rubber roller having a rubber layer formed thereon was produced. Both end portions of the rubber layer were cut so that the length of the rubber layer was 240 mm. This unground rubber roller is set in a grinding machine equipped with a grinding wheel GC80 (trade name, manufactured by company), and the outer diameter of the rubber layer is 10 mm at a rotational speed of 2000 RPM and a feed speed of 500 m / min as grinding conditions. The rubber roller was produced by grinding.

  Next, the manufacturing method of the electroconductive functional layer arrange | positioned on the outer periphery of a rubber roller is demonstrated.

  40 parts by mass of a styrene-based thermoplastic elastomer (trade name: Dynalon 4600P, manufactured by JSR) and 60 parts by mass of an amide-based thermoplastic elastomer (trade name: Pebax 4033, manufactured by Atofina Japan) were prepared. Furthermore, 40 parts by mass of carbon black (trade name: Toka Black # 4300, manufactured by Tokai Carbon Co., Ltd.), 10 parts by mass of magnesium oxide, and 1 part by mass of calcium stearate were added. The conductive functional layer material is melt kneaded at 20 to 220 ° C. using a pressure kneader, cooled, pulverized with a pulverizer, and granulated at 140 ° C. to 200 ° C. using a single screw extruder. Thus, pellets for the conductive functional layer were produced. The conductive functional layer pellets were extruded and subjected to sizing and cooling processes to form a seamless tube having an inner diameter of 9.8 mm and a layer thickness of 100 μm. And while blowing compressed air into this seamless tube, it coat | covered on the rubber roller after grinding demonstrated above, and obtained the conductive rubber roller of Example 1. FIG.

[Example 2]
A conductive rubber roller was prepared in the same manner as in Example 1 except that the liquid polyisoprene-1 was changed to liquid polyisoprene-2 [trade name: LIR-30, manufactured by Kuraray Co., Ltd.] without water addition. .

Example 3
A conductive rubber roller was prepared in the same manner as in Example 1 except that the liquid polyisoprene-1 was changed to liquid polybutadiene [trade name: LBR-300, manufactured by Kuraray Co., Ltd.] to which water was not added.

Example 4
Example except that 50 parts by mass of liquid polyisoprene-1 was used and 25 parts by mass of liquid polyisoprene-1 and 25 parts by mass of liquid polybutadiene [trade name: LBR-300, manufactured by Kuraray Co., Ltd.] were used. In the same manner as in Example 1, a conductive rubber roller was prepared.

Example 5
A conductive rubber roller was prepared in the same manner as in Example 1 except that the amount of liquid polyisoprene-1 used was changed from 50 parts by mass to 20 parts by mass.

Example 6
A conductive rubber roller was prepared in the same manner as in Example 1 except that the amount of liquid polyisoprene-1 used was changed from 50 parts by mass to 70 parts by mass.

Example 7
A conductive rubber roller was prepared in the same manner as in Example 1 except that the amount of calcium carbonate used was changed from 50 parts by mass to 20 parts by mass.

Example 8
A conductive rubber roller was produced in the same manner as in Example 1 except that the amount of calcium carbonate used was changed from 50 parts by mass to 70 parts by mass.

Example 9
In place of EPDM-1, EPDM [trade name: EPT4021, manufactured by Mitsui Chemicals, Mooney viscosity (100 ° C., ML1 + 4) is 24, diene content is 10.6% by mass] (EPDM-2) was used. A conductive rubber roller was prepared in the same manner as in Example 1 except for the above.

  In Examples 1 to 9, a conductive rubber roller having good processability could be manufactured by an inexpensive manufacturing process. In addition, it was possible to prevent bleeding of the surface of the conductive rubber roller caused by the migratory oil and softener such as a plasticizer. As a result, phenomena such as changing the current value (resistance value) of the conductive rubber roller, contaminating the photoconductor, and causing toner fixation do not occur.

[Comparative Example 1]
A conductive rubber roller was prepared in the same manner as in Example 1 except that the liquid polyisoprene-1 was changed to paraffin oil [trade name: Diana Process Oil PW-380, manufactured by Idemitsu Kosan Co., Ltd.].

  However, since paraffin oil was used, bleeding on the surface of Gorolla was observed. Then, the current value change before and after the severe storage of the conductive rubber roller, which is considered to be one of the causes, is a 40% increase in the current value of the conductive rubber roller.

[Comparative Example 2]
A conductive rubber roller was prepared in the same manner as in Example 1 except that calcium carbonate was not used.

  However, since calcium carbonate was removed, the rubber composition contracted during extrusion, and the adhesion with the core metal was not good, and a good rubber roller could not be obtained. Since a good rubber roller was not obtained, all physical properties were not measured.

  Tables 1 and 2 summarize the compositions (parts by mass) and evaluation results of the rubber compositions for the examples and comparative examples.

  EPDM-1 and EPDM-2 are rubber components. Liquid polyisoprene-1, liquid polyisoprene-1 and liquid polybutadiene are liquid rubbers.

Claims (9)

After the rubber composition is extruded using an extruder, the core metal is continuously passed through the crosshead die of the extruder, and the rubber composition is arranged in a layer on the outer peripheral surface of the core metal In the method for producing a conductive rubber roller having a rubber layer produced through a vulcanization step under no pressure,
The rubber composition contains an ethylene-propylene-nonconjugated diene copolymer rubber, calcium carbonate, and a liquid rubber.   The method for producing a conductive rubber roller according to claim 1, wherein the liquid rubber is liquid polyisoprene, liquid polybutadiene, or a mixture thereof.   The method for producing a conductive rubber roller according to claim 2, wherein the liquid polyisoprene is a water-added liquid polyisoprene.   The total amount of the liquid rubber contained in the rubber composition is 20 parts by mass or more and 70 parts by mass or less when the rubber component contained in the rubber composition is 100 parts by mass. 4. A method for producing a conductive rubber roller according to any one of items 1 to 3.   5. The calcium carbonate contained in the rubber composition is 20 parts by mass or more and 70 parts by mass or less when the rubber component contained in the rubber composition is 100 parts by mass. The manufacturing method of the electroconductive rubber roller in any one.   6. The method for producing a conductive rubber roller according to claim 1, wherein the calcium carbonate has an average particle size of 1.0 μm or more and 4.0 μm or less. The Mooney viscosity measured at 100 ° C. of the ethylene-propylene-nonconjugated diene copolymer rubber is 15 or more and 90 or less, and
The method for producing a conductive rubber roller according to any one of claims 1 to 6, wherein the ethylene-propylene-nonconjugated diene copolymer rubber has a diene content of 8% by mass or more and 15% by mass or less.   The method for producing a conductive rubber roller according to claim 1, wherein at least one conductive functional layer is formed on the outer peripheral surface of the rubber layer.   The method for producing a conductive rubber roller according to claim 1, wherein the conductive functional layer is formed of a seamless tube containing a thermoplastic elastomer.