JP4350143B2 - Conductive rubber roller, transfer roller, and image forming apparatus - Google Patents

Description

  The present invention relates to a conductive rubber roller used in an image forming apparatus such as an electrophotographic copying apparatus, a printer, and an electrostatic recording apparatus. Specifically, transfer that transfers a transferable image of a toner image formed and supported on an image carrier such as an electrophotographic photosensitive member by an electrophotographic process or an electrostatic recording process onto a recording medium such as paper or a transfer material. The present invention relates to a transfer roller of the apparatus.

Various electroconductive rubber parts such as electroconductive rollers are used in various electrophotographic apparatuses such as electrostatic copying machines, laser printers and facsimile machines. The conductive rubber member has a moderate elasticity and a volume resistivity value of 10 ^{5 to} 10 ¹⁰ Ω · cm, a resistance value variation and a resistance value variation due to an applied voltage are small, and a stable resistance value is obtained. The resulting material is used. As the material, epichlorohydrin rubber / acrylonitrile butadiene rubber is widely used (for example, see Patent Document 1).

In recent years, a conductive rubber roller having a lower resistance is required in order to cope with colorization and high image quality. Therefore,
・ Use epichlorohydrin rubber alone,
・ Ion conductive agent can be added
Ethylene oxide / propylene oxide / ethylene glycol-propylene oxide having a copolymerization ratio of 50 to 95 mol% / 1 to 49 mol% / 1 to 10 mol% and a number average molecular weight Mn of 10,000 or more Mixing allyl glycidyl ether terpolymer,
Thus, a proposal has been made to lower the volume resistivity (see, for example, Patent Document 2). However, in general, in the case of a conductive rubber roller using such a rubber elastic body, the resistance value changes due to environmental fluctuations in temperature and humidity, so the image quality changes depending on the use environment, and the material surface bleeds. Problems such as photoconductor contamination have not been solved.

  In addition, the conductive rubber roller is desired to have a moderately low hardness in addition to the above characteristics in order to improve the adhesion to the drum. When the roller hardness is high, the nip width with the photosensitive drum or the like becomes small, so that the transfer rate is lowered, and image defects are likely to occur due to wear or damage on the surface of the electrophotographic photosensitive member. On the other hand, if the hardness is too low, the compression set is too soft and the compression set becomes large and the durability is inferior, and the conveying force becomes too strong and the image is liable to be defective.

  Examples of the method for reducing the hardness of the conductive rubber roller include a method using various additives such as a softening agent and a plasticizer. However, when a conductive rubber roller added with a softener or plasticizer is used in contact with the photosensitive drum, various low molecular weight additives bleed out from the inside of the conductive rubber roller and adhere to the surface of the electrophotographic photosensitive member. Problems such as deterioration and electrophotographic photoreceptor contamination are likely to occur.

For this reason, a method for obtaining a sponge rubber roller using a chemical foaming agent is generally used to reduce the hardness of the conductive rubber roller. In recent years, high-quality images have been studied and the variation in the cell diameter of the conductive rubber roller has been reduced, and the demand for a sponge roller having a fine cell diameter has been increasing. By the production method using the continuous vulcanization method (for example, see Patent Document 3) Further cost reduction is expected.
JP 2002-287456 A JP 2002-105305 A Japanese Patent Laid-Open No. 2002-221859

  An object of the present invention relates to a conductive rubber roller used in an electrophotographic process such as a copying machine or a laser beam printer, which is easy to manufacture, low in cost, free from contamination of a member to be charged, and electrically An object of the present invention is to provide a conductive rubber roller excellent in fluctuation and durability.

  Another object of the present invention is to provide a transfer roller using the conductive rubber roller and an image forming apparatus including the transfer roller.

In accordance with the present invention, in a conductive rubber roller used in an electrophotographic process,
The rubber component of the conductive rubber roller is an acrylonitrile butadiene rubber having an acrylonitrile content of at least 15 mass% and at most 25 mass%;
An epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more;
Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) satisfying a copolymerization ratio of (A) + (B) <90 mol% and satisfying (B) + (C) <20 mol% And a copolymer of
A conductive rubber roller is provided in which the rubber composition of the rubber component has a Mooney viscosity (ML1 + 4 100 ° C.) of 30 or more and 70 or less.

  According to the present invention, there is provided a transfer roller characterized in that the transfer roller used in the transfer device of the electrophotographic process uses the conductive rubber roller described above.

  According to the present invention, there is provided an image forming apparatus characterized in that, in an image forming apparatus incorporating an electrophotographic process, a transfer roller used in the transfer apparatus is the transfer roller.

  As described above, the conductive rubber roller of the present invention is suitable as a conductive rubber roller having a uniform foam cell diameter, easy production, low cost, excellent electrical variation and durability, and no bleed. Then, it is possible to provide a transfer roller using the conductive rubber roller of the present invention and an image forming apparatus including the transfer roller.

  Hereinafter, embodiments of the present invention will be described in detail.

The conductive rubber roller of the present invention comprises at least acrylonitrile content of 15% by mass or more and 25% by mass or less of acrylonitrile butadiene rubber,
An epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more;
Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) satisfying a copolymerization ratio of (A) + (B) <90 mol% and satisfying (B) + (C) <20 mol% And a copolymer.

  When the acrylonitrile content is less than 15% by mass, the volume resistivity value is high, and when it exceeds 25% by mass, the resistance value change due to the environment increases.

  In addition, when the ethylene oxide content is less than 70 mol%, the volume resistivity value is high, and in order to obtain a predetermined resistance value, it is necessary to contain a large amount of epichlorohydrin-based rubber whose material unit price is expensive, Material costs will increase. Moreover, durability deteriorates.

  When the copolymerization ratio (A) + (B) of ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) is 90 mol% or more, the crystallinity that inhibits electric conduction increases, and the volume resistivity The value also increases. Since allyl glycidyl ether (C) is relatively reduced, the crosslinking site by allyl glycidyl ether (C) becomes insufficient, and it is difficult to co-crosslink with epichlorohydrin rubber or acrylonitrile butadiene rubber. Since the three-dimensional structure due to crosslinking becomes insufficient, the surface of the member is bleed and the member to be charged is contaminated.

  On the other hand, when the copolymerization ratio (B) + (C) is 20 mol% or more, ethylene oxide (A) that contributes to electric conduction decreases, and thus the volume resistivity value increases. Therefore, if the copolymerization ratio is not as described above, a reduction in resistance cannot be realized, resulting in an increase in material cost.

  The epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more is preferably an epichlorohydrin / ethylene oxide / allyl glycidyl ether terpolymer. Since allyl glycidyl ether is co-crosslinked with a copolymer of ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C), a three-dimensional structure is properly formed and bleeding can be suppressed. The volume resistivity value is reduced by copolymerizing ethylene oxide.

  When the rubber component in the present invention is 100% by mass, the content of acrylonitrile butadiene rubber is preferably 30% by mass or more, and more preferably 50% by mass or more. Acrylonitrile butadiene rubber has less resistance change due to the environment and is less expensive than the terpolymer of epichlorohydrin rubber / epichlorohydrin / ethylene oxide / allyl glycidyl ether. And material costs can be reduced.

  In addition, since the terpolymer of epichlorohydrin / ethylene oxide / allyl glycidyl ether is excellent in water absorption, if it is contained in a large amount, there will be a lot of water in the rubber composition. , The foam cell diameter is changed and many problems occur. Therefore, 20 mass% or less is preferable with respect to 100 mass% of rubber components, and 10 mass% or less is more preferable.

  In the present invention, the Mooney viscosity (ML1 + 4 100 ° C.) obtained by measuring the viscosity and vulcanization characteristics of the unvulcanized rubber of the rubber composition needs to be 30 or more and 70 or less. The conductive rubber roller is preferably produced by vulcanization and foaming by means of high-frequency molecular vibration heating means and having a foamed cell diameter of 50 μm or more and 300 μm or less, wherein the molecular vibration heating means generates microwaves. A device (UHF) is more preferable.

  When the Mooney viscosity of the rubber composition is less than 30, deformation during vulcanization / foaming is large and it is difficult to press-fit into the conductive shaft. Moreover, in order to obtain a predetermined outer diameter, it is necessary to mold the tube large, and the amount of polishing also increases. In addition, if a deformed tube is used as a conductive rubber roller, durability due to energization is deteriorated. When the Mooney viscosity exceeds 70, the extrudability deteriorates, the irregularities on the tube surface increase, and the amount of polishing for obtaining a predetermined outer diameter increases. Further, a good foam cannot be obtained and the hardness becomes high, resulting in a decrease in transfer performance.

  Also, if the foamed cell diameter is less than 50 μm, when the conductive rubber roller is pressed against the member to be charged, a good nip cannot be secured, and the toner cannot be uniformly transferred and the image deteriorates. It becomes easy. When the foamed cell diameter exceeds 300 μm, the unevenness on the surface of the roller after polishing is large and the outer diameter accuracy tends to be lowered. In addition, the image quality is deteriorated due to peeling of rubber on the roller surface and adhesion of polishing residue. The foam cell diameter is more preferably 50 μm or more and 200 μm or less.

  The filler other than the rubber component used in the conductive rubber roller of the present invention may contain other components used in general rubber as necessary. For example, vulcanizing agents such as sulfur and organic sulfur-containing compounds, various vulcanization accelerators, foaming agents, processing aids such as various lubricants and subs, anti-aging agents, vulcanizing aids such as zinc oxide and stearic acid, carbonic acid Fillers such as calcium, talc, silica, clay, and carbon black can be blended as necessary.

  The rubber composition used for the conductive rubber roller is formed by kneading using an open roll or a closed kneader or the like using an extruder.

A method for producing a conductive rubber roller will be described with reference to FIG. The rubber component of the conductive rubber roller 6 of the present invention includes at least acrylonitrile content of 15% by mass or more and 25% by mass or less of acrylonitrile butadiene rubber,
An epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more;
Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) satisfying a copolymerization ratio of (A) + (B) <90 mol% and satisfying (B) + (C) <20 mol% And a copolymer of
The rubber composition of the rubber component has a Mooney viscosity (ML1 + 4 100 ° C.) of 30 or more and 70 or less.

  The rubber composition of the conductive rubber roller is extruded into a tube shape by an extruder, heated by a microwave vulcanizer (UHF) which is a high-frequency molecular vibration heating means, vulcanized and foamed, and conductive rubber (elastic body) Make a tube. Thereafter, the conductive rubber body 6 is obtained by inserting the conductive shaft body 61 and polishing the vulcanized foam rubber layer 62 until a predetermined outer diameter is obtained. Further, the conductive rubber roller 6 of the present invention can be formed into a conductive rubber roller having a two-layer structure or more by providing a layer of rubber / resin or the like on the outer periphery of the vulcanized foam rubber layer 62 as necessary.

  The conductive rubber roller of the present invention is a foamed conductive rubber roller, and has the same formulation (same member) produced by a continuous vulcanization method using a microwave generator so that the foam cell diameter is 50 μm or more and 300 μm or less. Vulcanized and foamed by the above method. However, if the microwave output, line speed, and hot stove temperature change, the foam cell diameter may change. By being within the scope of the present invention, the adhesion to the electrophotographic photosensitive member is increased and image defects are less likely to occur.

  Next, an example in which the transfer roller according to the present invention is used in an image forming apparatus incorporating an electrophotographic process will be described with reference to the drawings.

  The image forming apparatus shown in FIG. 2 is a laser printer using an electrophotographic process cartridge, and FIG. 2 is a longitudinal sectional view showing a schematic configuration thereof. Further, the image forming apparatus shown in the figure is equipped with a transfer means having the conductive rubber roller of the present invention as a transfer roller.

  The image forming apparatus shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 as an image carrier. In the photosensitive drum 1, a photosensitive layer made of an organic photoconductor (OPC) is provided on the outer peripheral surface of a grounded cylindrical aluminum substrate. The photosensitive drum 1 is driven to rotate at a predetermined process speed (circumferential speed), for example, 50 mm / sec, in the direction of arrow R1 by a driving means (not shown).

  The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 as a contact charging member. The charging roller 2 is disposed in contact with the surface of the photosensitive drum 1 and is driven to rotate in the direction of arrow R2 as the photosensitive drum 1 rotates in the direction of arrow R1. An oscillating voltage (AC voltage VAC + DC voltage VDC) is applied to the charging roller 2 by a charging bias application power source (high voltage power source), whereby the surface of the photosensitive drum 1 is uniformly charged to −600 V (dark portion potential Vd). It is processed. The surface of the photosensitive drum 1 after charging is scanned and exposed by a laser beam 3 output from a laser scanner and reflected by a mirror, that is, a laser beam modulated in accordance with a time-series electric digital image signal of target image information. Receive. As a result, an electrostatic latent image corresponding to the target image information (bright part Vl = −150 V) is formed on the surface of the photosensitive drum 1.

  The electrostatic latent image is reversely developed as a toner image with negatively charged toner attached thereto by a developing bias applied to the developing sleeve of the developing device 4.

  On the other hand, a transfer material 7 such as paper fed from a paper feed unit (not shown) is guided by a transfer guide, and a transfer unit (transfer nip) between the photosensitive drum 1 and a transfer roller composed of a conductive rubber roller 6. Part) T is supplied so as to match the timing of the toner image on the photosensitive drum 1. The toner image on the photosensitive drum 1 is transferred to the surface of the transfer material 7 supplied to the transfer portion T by the transfer bias applied to the transfer roller by the transfer bias application power source. At this time, toner remaining on the surface of the photosensitive drum 1 without being transferred to the transfer material 7 (residual toner) is removed by the cleaning blade 8 of the cleaning device 9.

  The transfer material 7 that has passed through the transfer portion T is separated from the photosensitive drum 1 and introduced into the fixing device 10, where the toner image is subjected to fixing processing, and an image forming apparatus main body (not shown) as an image formed product (print). It is discharged outside.

  Next, the conductive rubber roller of the present invention was produced as follows.

  FIG. 3 shows an apparatus for producing a conductive rubber roller by continuous vulcanization using microwaves. The extrusion vulcanization apparatus used in the present invention has a total length of 13 m, and includes an extruder 11, a microwave vulcanization apparatus (UHF) 12, a hot air vulcanization apparatus (HAV) 13, a take-up machine 14, and a regular cutting machine 15. The

The rubber component of the rubber composition comprises at least acrylonitrile butadiene rubber having an acrylonitrile content of 15% by mass to 25% by mass;
An epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more;
Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) satisfying a copolymerization ratio of (A) + (B) <90 mol% and satisfying (B) + (C) <20 mol% And a copolymer of
The rubber composition of the rubber component has a Mooney viscosity (ML1 + 4 100 ° C.) of 30 or more and 70 or less. These rubber components are kneaded using a closed kneader such as a Banbury mixer or a kneader, and then a vulcanizing agent and a foaming agent are contained in an open roll, formed into a ribbon shape by a ribbon forming dispenser, and the extruder 11 It is thrown into. The UHF 12 conveys a rubber belt extruded from the extruder 11 with a mesh belt coated with PTFE (polytetrafluoroethylene) resin or a roller coated with PTFE resin, and the HAV 13 is a roller coated with PTFE resin. Is being transported. The UHF 12 and the HAV 13 are connected by a roller coated with PTFE resin.

  The lengths of the devices 12, 13, and 14 are as shown, and in this embodiment, the lengths are 4m, 6m, and 1m, respectively. The distance between the UHF 12 and the HAV 13 and the distance between the HAV 13 and the take-up machine 14 are set to be 0.1 m to 1.0 m.

  In the manufacturing apparatus by continuous vulcanization using the microwave, the rubber tube formed into a tube shape from the extruder 11 and extruded is UHF 12 set to an oven atmosphere temperature of 220 ° C. immediately after being extruded from the extruder 11. Conveyed in. The rubber tube is irradiated with microwaves, the rubber tube is heated and vulcanized and foamed, and then conveyed to the HAV 13 to complete the vulcanization.

  In the above vulcanization and foaming process, the microwave irradiated in the microwave vulcanization furnace of UHF12 is preferably 2450 ± 50 MHz. By being in this range, the rubber tube has less irradiation unevenness and can be irradiated efficiently. is there. The temperature of the hot air in the UHF furnace is preferably 150 ° C. or higher and 250 ° C. or lower, and particularly preferably 180 ° C. or higher and 230 ° C. or lower.

  Immediately after being discharged from the winder 14 after vulcanization and foaming, it was cut into a desired size by a regular cutting machine 15 to produce a tubular conductive rubber molded product. Next, a conductive shaft body having a diameter of 4 mm or more and 10 mm or less is press-fitted into the inner diameter portion of the tube-shaped conductive rubber molding to obtain a roller-shaped molding.

  Hereinafter, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to these examples. Tables 1 and 2 show the blending ratios and test results of the rubber materials used in the examples and comparative examples. In addition, the unit of a compounding quantity is a mass part.

The rubber materials used in each example and comparative example are as follows.
Acrylonitrile butadiene rubber [1 Bonded acrylonitrile (AN) amount 18% by mass, trade name: Nipol DN401LL, manufactured by Nippon Zeon Co., Ltd.]
[2 Bonded acrylonitrile (AN) amount 18% by mass, trade name: NipolDN401L, manufactured by Nippon Zeon Co., Ltd.]
[Amount of bound acrylonitrile (AN) 35% by mass, trade name: N230SV, manufactured by JSR Corporation]
-Epichlorohydrin rubber [ethylene oxide (EO) content 73 mol%, trade name: EPION301, manufactured by Daiso Corporation]
[Ethylene oxide (EO) content 56 mol%, trade name: Hydrin T3106S, manufactured by Nippon Zeon Co., Ltd.]
-Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) copolymer [ethylene oxide-propylene oxide-allyl glycidyl ether copolymerization ratio (mol%) = 87: 1: 12, trade name: Zeospan 8010, manufactured by Nippon Zeon Co., Ltd.]
[Ethylene oxide-propylene oxide-allyl glycidyl ether copolymerization ratio (mol%) = 90: 6: 4, trade name: Zeospan 8030, manufactured by Nippon Zeon Co., Ltd.]
・ Vulcanizing agent [Sulfur, trade name: Sulfax PMC, manufactured by Tsurumi Chemical Co., Ltd.]
・ Vulcanization accelerator [2-Mercaptobenzothiazole (M), trade name: Noxeller M, manufactured by Ouchi Shinsei Chemical Co., Ltd.]
[Dibenzothiazyl disulfide (DM), trade name: Noxeller DM, manufactured by Ouchi Shinsei Chemical Co., Ltd.]
[Tetraethylthiuram disulfide (TET); trade name: Noxeller TET, manufactured by Ouchi Shinsei Chemical Co., Ltd.]
・ Vulcanization accelerating aid [Zinc oxide, trade name: 2 types of zinc white, manufactured by Hakusuitec Co., Ltd.]
・ Auxiliary agent [Stearic acid, trade name: LUNAC S20, manufactured by Kao Corporation]
-Filler [Carbon black 1, trade name: Asahi # 35, manufactured by Asahi Carbon Co., Ltd.]
[Carbon Black 2, trade name: Asahi # 15, manufactured by Asahi Carbon Co., Ltd.]
[Calcium carbonate, trade name: Super SS, manufactured by Maruo Calcium Co., Ltd.]
-Foaming agent [p. p′-oxybissulfonyl hydrazide (OBSH), trade name: Neoselbon N1000 # S, manufactured by Eiwa Kasei Co., Ltd.]
In addition, the conductive rubber member of an Example and a comparative example is a microwave vulcanization furnace (UHF) and a continuous hot air furnace which irradiate a microwave of 2450 MHz using the above-mentioned manufacturing apparatus by the combination of Table 1 and Table 2. Was vulcanized. Thus, the tube-shaped rubber vulcanizate was produced under the condition that the hardness was 20 ° to 50 °. Next, a conductive shaft body having a diameter of 6 mm was inserted into the inner diameter portion of the tubular rubber vulcanizate to obtain a roller-shaped molded body. This molded body was prepared by polishing so that the outer diameter was 14 mm.

<Mooney viscosity>
Using a Mooney viscometer (manufactured by Shimadzu Corp.), the rubber composition was inserted into a cylindrical die, the rotor was rotated, and the torque was measured. The measuring method is based on JIS K-6300 and is a numerical value obtained by measuring (ML1 + 4) at 100 ° C.

<Roller electrical resistance and environmental fluctuation>
Under normal temperature and humidity (23 ° C / 55% RH) environment, the shaft of the conductive rubber roller is subjected to a load of 4.9N on one side, and is crimped to an aluminum drum with an outer diameter of 30mm, and the shaft is rotated. A roller resistance was measured by applying a voltage of 2 kV between the body and the aluminum drum.

  The range of environmental fluctuation of the roller resistance value is the roller resistance (T1) under the low temperature and low humidity environment (15 ° C./10% RH) and the roller resistance (T2) under the high temperature and high humidity environment (32.5 ° C./80% RH). Logarithmic difference was calculated by the formula: log10 (T1) -log10 (T2). In the evaluation, 1.5 or less was good: ◯ and a value exceeding 1.5 was bad: x.

<Durability of roller energization>
A conductive rubber roller is placed in an environment of 50 ° C., and the shaft body and the aluminum drum are placed in a state where the shaft body is pressed against an aluminum drum having an outer diameter of 30 mm so that a load of 4.9 N on one side is applied to both ends and rotated. During this period, a constant current of 80 μA was continuously applied for 25 hours. Then, after returning to a room temperature and normal humidity (23 ° C./55% RH) environment and leaving it to stand for 24 hours or more, the roller resistance was measured again. Here, the difference in logarithm between the initial resistance value and the resistance value after endurance is 0.3 or more as an endurance fluctuation digit, and a crack is generated on the roller surface is judged as bad: x, and the others are good: ○ .

<Electrophotographic photoconductor contamination>
The obtained conductive rubber roller is brought into contact with the electrophotographic photosensitive member of the cartridge used in the laser printer Laserjet 4000N manufactured by Hewlett Packard, a load of 1000 g is applied to both ends, and the environment is 40 ° C./95% RH for one week. I left it alone. After standing, the load was removed, and the surface state of the electrophotographic photosensitive member was observed, and those with no discoloration or sticking were judged as good: ◯, those with discoloration or sticking were judged as bad: x.

<Processability>
Extruded into a tube with an extruder and heated with a microwave vulcanizer (UHF) to produce a conductive rubber (elastic body) tube. Thereafter, in the step of inserting the conductive shaft body and polishing it to a predetermined outer diameter, it is necessary to polish the outer diameter by 4 mm (one side 2 mm) or more from the tube outer diameter after inserting the conductive shaft body. Some were bad: x, others were good: ◯.

  In Comparative Example 1, the copolymerization ratio is (A) + (B) <90 mol% and does not satisfy (B) + (C) <20 mol%. Ethylene oxide (A) / propylene oxide (B) / It is an example at the time of using the copolymer of allyl glycidyl ether (C). For this reason, since the copolymerization ratio of allyl glycidyl ether is 4 mol% and there are few cross-linking sites and co-crosslinking is difficult, the electrophotographic photosensitive member as the member to be charged is contaminated.

  Comparative Examples 2 and 3 are examples in which the Mooney viscosity (ML1 + 4 100 ° C.) of the rubber composition does not satisfy 30 or more and 70 or less, and if it is less than 30, deformation of the tube molded into a tube shape and vulcanized / foamed The energization durability greatly deteriorated. The roller surface is cracked and cannot be said to be a good conductive rubber roller. Moreover, since the amount of deformation is large, it is necessary to increase the outer diameter of the tube, resulting in an increase in cost. When the Mooney viscosity exceeds 70, the extrudability deteriorates, the irregularities on the tube surface increase, and the amount of polishing for obtaining a predetermined outer diameter increases.

  Comparative Example 4 is an example in which the ethylene oxide content of the epichlorohydrin rubber is less than 70 mol%, and the current carrying durability is deteriorated. Further, in comparison with Example 3, in order to confirm that the resistance value is high and to obtain an equivalent resistance value, it is necessary to contain a large amount of epichlorohydroline, which increases the cost.

  Comparative Examples 5 and 6 are examples in which the acrylonitrile content of the acrylonitrile butadiene rubber does not satisfy 15% by mass or more and 25% by mass or less, and although the resistance value decreases, the fluctuation range of the resistance value due to the environment increases.

  As described above, the above-described problems can be solved by the conductive rubber roller of the present invention.

It is a schematic block diagram of the conductive rubber roller of this invention. 1 is an overall cross-sectional view of an image forming apparatus according to the present invention. It is a manufacturing apparatus by continuous vulcanization using the microwave of the conductive rubber roller of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging apparatus 3 Exposure means 4 Developing apparatus 5 Toner 6 Conductive rubber roller (transfer roller)
7 Recording medium 8 Cleaning blade 9 Waste toner container 10 Fixing device 11 Extruder 12 Microwave vulcanizing device (UHF)
13 Hot air vulcanizer (HAV)
14 Take-up machine 15 Standard cutting 61 Conductive shaft body 62 Vulcanized foam rubber layer

Claims (6)

In the conductive rubber roller used in the electrophotographic process,
The rubber component of the conductive rubber roller is an acrylonitrile butadiene rubber having an acrylonitrile content of at least 15 mass% and at most 25 mass%;
An epichlorohydrin rubber having an ethylene oxide content of 70 mol% or more;
Ethylene oxide (A) / propylene oxide (B) / allyl glycidyl ether (C) satisfying a copolymerization ratio of (A) + (B) <90 mol% and satisfying (B) + (C) <20 mol% And a copolymer of
A conductive rubber roller, wherein the rubber composition of the rubber component has a Mooney viscosity (ML1 + 4 100 ° C.) of 30 or more and 70 or less.   The conductive rubber roller according to claim 1, wherein the epichlorohydrin rubber is a terpolymer of epichlorohydrin / ethylene oxide / allyl glycidyl ether.   3. The conductive rubber roller according to claim 1, wherein the conductive rubber roller is vulcanized and foamed by high-frequency molecular vibration heating means, and the size of the foamed cell is 50 μm or more and 300 μm or less.   The conductive rubber roller according to claim 3, wherein the molecular vibration heating means is a microwave generator (UHF).   A transfer roller for use in a transfer apparatus for an electrophotographic process, wherein the conductive rubber roller according to any one of claims 1 to 4 is used.   6. An image forming apparatus according to claim 5, wherein the transfer roller used in the transfer device is the transfer roller according to claim 5.