JP2007328025A - Conductive rubber roller, process cartridge provided with it and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rubber roller which is reduced in compression set while satisfying requirement of low resistance without soiling members such as a photoreceptor or a transfer belt, and to provide a process cartridge provided with the conductive roller, and an image forming apparatus. <P>SOLUTION: The conductive rubber roller is provided with conductive core material and an elastic layer provided on the conductive core material. The elastic layer is formed from epichlorohydrin rubber and a terpolymer of ethyleneoxide/propylene oxide/allyl compound glycidyl ether. Ratio (b/a), by mass, of the terpolymer (b) of ethyleneoxide/propylene oxide/allyl compound glycidyl ether to the epichlorohydrin rubber (a) is 0.05-1.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 by a toner image formed and supported on an image carrier such as an electrophotographic photosensitive member by an image forming means such as 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 conductive rubber roller such as a transfer roller or a primary transfer roller of the apparatus.

  In an image forming apparatus such as an electrophotographic copying machine or an electrostatic recording apparatus, a contact charging method in which a conductive rubber roller to which a voltage is applied is pressed against the surface of a photosensitive member to be charged is the mainstream. In this system, a conductive rubber roller is used around each photosensitive drum, which is the center of image formation, for each process such as charging and transfer.

  In recent years, polar rubbers such as acrylonitrile butadiene rubber and epichlorohydrin rubber have been used for the rubber component of such conductive rubber rollers. Polar rubber has conductivity (ionic conductivity) due to the presence of polar groups in the polymer, and is known to be suitable for conductive rubber rollers because of its variation in electrical resistance and small voltage dependence of electrical resistance. It has been.

The volume specific resistance required for the elastic body layer of the conductive rubber roller is often 2 × 10 ⁹ Ω · cm or less. When the rubber component is acrylonitrile butadiene rubber alone, the volume specific resistance of the vulcanizate is about 2 × 10 ⁹ to 1 × 10 ¹⁰ Ω · cm, resulting in insufficient conductivity. Moreover, since acrylonitrile butadiene rubber has poor ozone resistance, sufficient current-carrying durability cannot be obtained.

In order to obtain a desired volume resistivity, Patent Document 1 discloses that an acrylonitrile butadiene rubber is an epichlorohydrin-based rubber known to have a volume resistivity of vulcanizate of about 1 × 10 ^{7 to} 3 × 10 ⁹ Ω · cm. A technique for blending is disclosed.

  In recent years, a conductive rubber roller having a lower resistance has been demanded in order to cope with colorization and high image quality. For this reason, methods using epichlorohydrin rubber alone or adding various ionic conductive agents such as quaternary ammonium salts containing perchlorate ions and chloride ions are also used (for example, Patent Document 2).

  However, in general, in the case of a conductive rubber roller using such a rubber elastic body, there is a problem that the image quality changes depending on the use environment because the resistance value changes due to environmental fluctuations of temperature and humidity. In particular, epichlorohydrin rubber has a problem that it is easily affected by humidity and has a large environmental variation in resistance value. In addition, the method of adding various ionic conductive agents such as quaternary ammonium salts may cause the resistance value to change over time due to contamination or energization due to surface migration. Durability may not be obtained.

  In addition, when epichlorohydrin rubber or quaternary ammonium salt containing perchlorate ion or chloride ion is blended, the compression set is significantly worsened due to the side reaction of chlorine, etc. And may produce dioxins.

  Therefore, Patent Document 3 describes a method for obtaining an elastic body having a good compression set while realizing a low resistance as described above, by using an ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer in epichlorohydrin rubber. A technique for quantitative blending is disclosed. Since the ethylene oxide-propylene oxide-allyl glycidyl ether copolymer contains ether oxygen, it functions to stabilize metal cations in the polymer and lower the electrical resistance. In addition, since the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer has a large polarity, it has excellent compatibility with other polar rubbers, and because allyl glycidyl ether has an unsaturated bond, Sulfur crosslinking is possible. Therefore, unlike conductive agents such as quaternary ammonium salts, bleeding and photoreceptor contamination are unlikely to occur. Further, according to Patent Document 3, since the ethylene oxide / propylene oxide / allyl glycidyl ether copolymer does not contain a halogen element, there is no problem such as a side reaction of chlorine unlike an epichlorohydrin rubber, and compression set A good rubber material can be obtained.

The conductive rubber roller in which the above-mentioned ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer is blended with polar rubber such as acrylonitrile butadiene rubber or epichlorohydrin rubber achieves a certain degree of resistance reduction. However, further improvements have been sought for compression set.
JP 2002-287654 A JP 2000-17118 A JP 2002-105305 A

  The present invention has been proposed in view of the above-described conventional problems. That is, the present invention provides a conductive rubber roller that satisfies the requirement of low resistance and reduces compression set without contaminating members such as a photoreceptor and a transfer belt, and a process cartridge and an image forming apparatus having the conductive rubber roller. For the purpose.

  The conductive rubber roller according to the present invention is a conductive rubber roller having a conductive core material and an elastic layer provided on the conductive core material, the elastic layer comprising epichlorohydrin rubber, ethylene oxide / propylene oxide / Allyl glycidyl ether terpolymer, the ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer is: 80 mol% or more and 90 mol% or less of ethylene oxide; more than 0 mol% A copolymer consisting of 10 mol% or less of propylene oxide; and 10 mol% or more and 20 mol% or less of allyl glycidyl ether, and the ethylene oxide / propylene oxide / allyl glycidyl with respect to part by mass (a) of the epichlorohydrin rubber. Ratio of mass part (b) of ether terpolymer (B / a) is characterized by a 0.05 ≦ b / a ≦ 1.0.

  In addition, a process cartridge and an image forming apparatus according to the present invention include the above-described conductive rubber roller.

  According to the conductive rubber roller of the present invention, the compression set can be improved without contaminating each member such as the photosensitive member or the transfer belt while realizing low resistance. In particular, it is suitable for use in a color image forming apparatus or the like that requires low resistance.

  First, a conductive rubber roller according to the present invention will be described with reference to FIG. FIG. 1 is an overall cross-sectional view of a conductive rubber roller according to the present invention, illustrating a primary transfer roller used for primary transfer of an image forming apparatus. The conductive rubber roller according to the present invention includes a cored bar 61 made of a good conductor such as aluminum, and an elastic layer 62 formed on the cored bar 61.

  As the core bar 61, a good conductor such as aluminum, stainless steel, plated iron, brass or an alloy containing these is preferably used. The cored bar 61 used in the present invention preferably has a diameter of 3 to 10 mm, and may be a metal tube having a thickness of about 0.1 to 1.5 mm or a rod shape. Good.

  The elastic layer 62 is formed from a known epichlorohydrin rubber and an ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer having a specific composition ratio. Since the ethylene oxide-propylene oxide-allyl glycidyl ether copolymer contains ether oxygen, it has a function of stabilizing the metal cation in the polymer and lowering the electric resistance. Therefore, in the ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer used in the present invention, it is important that the copolymerization ratio of allyl glycidyl ether is 10 mol% or more and 20 mol% or less. The polymerization ratio is more preferably 10 mol% or more and 15 mol% or less.

  Since allyl glycidyl ether has an unsaturated bond, it can also be crosslinked with other rubber components. Moreover, the segmental motion of the molecular chain depends on the copolymerization ratio of allyl glycidyl ether in the ternary copolymer described above. Therefore, when the copolymerization ratio of allyl glycidyl ether is less than 10 mol%, there is a problem that the compression set becomes large because there are few crosslinking points.

  In addition, when the copolymerization ratio of allyl glycidyl ether is not appropriate, resistance reduction due to ether oxygen is inhibited, or a significant resistance change occurs in a high temperature / high humidity environment where molecular motion is activated. growing. When the copolymerization ratio of allyl glycidyl ether exceeds 20 mol%, the number of crosslinking points becomes too large, and the degree of freedom of ether oxygen in the ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer is inhibited, Lowering resistance becomes difficult. Furthermore, when the copolymerization ratio of allyl glycidyl ether exceeds 20 mol%, tensile properties, fatigue properties, flex resistance, and the like deteriorate.

  In the case of the present invention, an ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer composed of allyl glycidyl ether having a specific copolymerization ratio and epichlorohydrin rubber may be blended. As a result, it is possible to balance the resistance change caused by the difference between the segmental motion of the molecular chain and the function of the ether oxygen in the main chain structure stabilizing the ions. In addition, it is possible to provide a conductive rubber roller having a good compression set while maintaining the low resistance characteristic of a conductive rubber roller containing a conventional ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer. It becomes.

  In addition, the copolymerization ratio of ethylene oxide and propylene oxide in the terpolymer of ethylene oxide / propylene oxide / allyl glycidyl ether used in the present invention is in the following range from the viewpoint of compatibility, electric resistance value, and the like. Is preferred. That is, ethylene oxide / propylene oxide = 50 mol% or more and 89 mol% or less / 1 mol% or more and 50 mol% or less is preferable with respect to 10 mol% or more and 20 mol% or less of allyl glycidyl ether.

  Moreover, the compounding quantity of the ethylene oxide-propylene oxide-allyl glycidyl ether ternary copolymer used by this invention is as follows.

When the mass part of epichlorohydrin rubber is a and the mass part of ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer is b, the ratio (b / a) is:
0.05 ≦ b / a ≦ 1.0

  If the mass ratio is less than 0.05, the resistance can be lowered, but the compression set becomes large, and if the mass ratio exceeds 1.0, the resistance of the resistance tends to increase, and the photoconductor May also contaminate.

  The rubber component used in the present invention contains epichlorohydrin rubber in addition to the above-mentioned ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer. The epichlorohydrin rubber is preferably an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (ECH-EO-AGE) in that sulfur vulcanization or effective vulcanization is possible. In particular, the copolymerization ratio of ethylene oxide in the epichlorohydrin rubber is more preferably 40 mol% or more. The epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer has a tendency that the volume specific resistance value of the vulcanized rubber decreases as the copolymerization ratio of ethylene oxide increases. For this reason, when the copolymerization ratio of ethylene oxide is less than 40 mol%, it is difficult to obtain an electric resistance value necessary for the elastic layer of the conductive rubber roller. Therefore, the blending ratio of epichlorohydrin rubber increases, and the environmental dependency is increased. Therefore, the copolymerization ratio of ethylene oxide in the epichlorohydrin rubber used in the present invention is preferably 38 mol% or more and 58 mol% or less.

  The rubber composition used in the conductive rubber roller according to the present invention can contain other components used in general rubber as necessary in addition to the above-described components. It is as illustrated in FIG.

Vulcanizing agent (sulfur, organic sulfur-containing compounds, etc.)
Various vulcanization accelerators Various lubricants Processing aids (sub, etc.)
Various anti-aging agents Various foaming agents (p, p'-oxybissulfonylhydrazide (OBSH), azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), etc.)
Various foaming aids (urea, etc.)
Vulcanizing aid (Zinc oxide, stearic acid, etc.)
Various fillers (calcium carbonate, talc, silica, clay, etc.)

  In addition, various ionic conductive agents can be blended as necessary to adjust the conductivity. However, since there is a possibility of contamination of the photoreceptor due to the transfer to the roller surface, the blending amount of the ionic conductive agent is as described above. It is preferable to set it to less than 2.0 parts by mass with respect to 100 parts by mass of the rubber main component.

  In addition, as a method for producing a conductive rubber roller according to the present invention, first, an unvulcanized conductive rubber composition is extruded into a tube shape by an extruder and heated in a vulcanizing can or a continuous vulcanizing furnace to conduct conductive rubber ( Elastic body) A tube is produced. Then, the conductive shaft body which apply | coated the adhesive agent to this conductive rubber tube is inserted, and a conductive shaft body and a conductive rubber tube are adhere | attached by heating further. After the treatment as described above, the conductive rubber roller according to the present invention is obtained by polishing to a predetermined outer diameter. Note that this method is an example, and co-extrusion of an unvulcanized rubber composition and a conductive shaft coated with an adhesive, vulcanization by loading the extruded rubber composition into a mold, etc. Various conventionally known manufacturing methods can be applied. Moreover, the conductive rubber roller according to the present invention can be provided with a layer of resin or the like on the outer periphery of the elastic layer, if necessary.

  Next, application examples of the conductive rubber roller according to the present invention will be shown. FIG. 2 is a schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller according to the present invention.

  A rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 1 that is repeatedly used as a first image bearing member is driven to rotate at a predetermined peripheral speed (process speed) in the direction of an arrow.

  The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the primary charger 2 during the rotation process. Reference numeral 32 denotes a primary charger power source. In this case, alternating current is superimposed on direct current, but direct current alone may be applied. Next, the photosensitive drum 1 receives exposure light 3 from an exposure unit (not shown), thereby forming an electrostatic latent image corresponding to a first color component image (for example, a yellow color component image) of a target full-color image. Is done. The exposure means includes a color separation / imaging exposure optical system for a full-color original image, a scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of image information, and the like. Illustrated.

  Next, the electrostatic latent image is developed with yellow toner Y as the first color by a first developing device (yellow color developing device 41). At this time, the developing devices of the second to fourth developing devices (magenta developing device 42, cyan developing device 43, and black developing device 44) are turned on and do not act on the photosensitive drum 1. . Therefore, the yellow toner image of the first color is not affected by the second to fourth developing devices.

  The intermediate transfer belt 5 is rotationally driven at the same peripheral speed as the photosensitive drum 1 in the direction of the arrow.

  The yellow toner image of the first color formed and supported on the photosensitive drum 1 passes through the nip portion between the photosensitive drum 1 and the intermediate transfer belt 5. In this process, primary transfer is sequentially performed on the outer peripheral surface of the intermediate transfer belt 5 by the electric field formed by the primary transfer bias applied from the primary transfer roller 6 to the intermediate transfer belt 5.

  The surface of the photosensitive drum 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer belt 5 is cleaned by the cleaning device 13.

  In the same manner, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer belt 5 and synthesized corresponding to the target full color image. A color toner image is formed.

  The secondary transfer roller 7 is disposed in parallel with the secondary transfer counter roller 8 so as to be separated from the lower surface of the intermediate transfer belt 5 by bearing in parallel.

  A primary transfer bias for sequentially superimposing and transferring toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer belt 5 is applied from a bias power source 30 with a polarity (for example, positive) opposite to that of the toner. . The applied voltage is, for example, in the range of +100 V to 2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive drum 1 to the intermediate transfer belt 5, the secondary transfer roller 7 can be separated from the intermediate transfer belt 5.

  The composite color toner image transferred onto the intermediate transfer belt 5 is then transferred from the paper feed roller 11 to the transfer material P fed via the transfer material guide 10. The composite color toner image on the intermediate transfer belt 5 is transferred to a transfer material P fed at a predetermined timing to a contact nip formed by the intermediate transfer belt 5 and the secondary transfer roller 7. In this contact nip, this transfer is performed by applying a secondary transfer bias from the bias power source 31 to the secondary transfer roller 7. By this secondary transfer bias, the composite color toner image is secondarily transferred from the intermediate transfer belt 5 to the transfer material P as the second image carrier. At this time, an apparatus for assisting charging of the toner image before the secondary transfer on the intermediate transfer belt is not added to the apparatus. The transfer material P that has received the transfer of the toner image is introduced into the fixing device 15 and heated and fixed.

  After the image transfer to the transfer material P is completed, a cleaning charging member 9 disposed so as to be detachable is brought into contact with the intermediate transfer belt 5 and a bias having a polarity opposite to that of the photosensitive drum 1 is applied. As a result, a charge having a polarity opposite to that at the time of primary transfer is imparted to the transfer residual toner that is not transferred to the transfer material P and remains on the intermediate transfer belt 5. Reference numeral 33 denotes a bias power source. Here, alternating current is superimposed on direct current and applied. The above-mentioned transfer residual toner charged to a polarity opposite to that at the time of primary transfer is electrostatically transferred to the photosensitive drum 1 at and near the nip portion with respect to the photosensitive drum 1, thereby cleaning the intermediate transfer member. Since this step can be performed simultaneously with the primary transfer, the throughput does not decrease.

  Next, a process cartridge in which the intermediate transfer belt and the electrophotographic photosensitive member are integrally supported will be described with reference to FIG. The process cartridge of the present invention only needs to be configured so that at least the intermediate transfer belt 5, the photosensitive drum 1, and the primary transfer roller 6 are integrally supported and detachable from the apparatus main body. In FIG. 3, an intermediate transfer belt cleaning device 13 and a charging member 9 for cleaning an electrophotographic photosensitive member are also attached as an integrated unit. In the present invention, as described above, the cleaning of the intermediate transfer belt is a mechanism necessary for charging the transfer residual toner to a polarity opposite to that of the primary transfer and returning it to the electrophotographic photosensitive member at the primary transfer portion. In this case, the cleaning charging member 9 made of a medium-resistance elastic body is used. The electrophotographic photosensitive member is cleaned by blade cleaning. This cartridge may be provided with a waste toner container (not shown) as a unit, and the transfer residual toner on both the intermediate transfer belt and the electrophotographic photosensitive member is discarded at the same time when the cartridge is replaced. ing.

  Further, the intermediate transfer belt may be stretched by two rollers, the secondary transfer counter roller 8 and the tension roller 12, so that the number of parts can be reduced and the size can be reduced. Here, the secondary transfer counter roller 8 is simultaneously a counter roller of the cleaning charging member 9. The tension roller 12 that rotates following the intermediate transfer belt has a sliding mechanism, is pressed in the direction of the arrow by a compression spring, and applies tension to the intermediate transfer belt. The slide width is about 1 to 5 mm, and the total pressure of the spring is about 5 to 100N. Further, the photosensitive drum 1 and the secondary transfer counter roller 8 have a coupling (not shown), and a rotational driving force is transmitted from the main body.

  FIG. 4 shows another example of the image forming apparatus. FIG. 4 is provided with the same number of photosensitive drums 1 as the number of developers necessary for image formation, and has the advantage that the printing speed of full-color printing is dramatically improved.

  The image forming apparatus shown in FIG. 4 uses an intermediate transfer belt. In this image forming apparatus, a visible image is formed on the photosensitive drum 1 in the same manner as in FIG. 2, and the toner is sequentially transferred and superimposed on the intermediate transfer belt 5, and then a bias having a polarity opposite to that of the toner is applied by the secondary transfer roller 7. Applied to the transfer material P and batch transferred. The developer remaining on the intermediate transfer belt is removed by the cleaning device 18.

  FIG. 5 shows an example in which the conductive rubber roller according to the present invention is used in a monochrome image forming apparatus. The monochrome image forming apparatus shown in FIG. 5 is an electrophotographic laser printer using a process cartridge, and FIG. 5 is a longitudinal sectional view showing a schematic configuration thereof. The image forming apparatus shown in FIG. 5 is equipped with a transfer device having a conductive rubber roller according to the present invention as a transfer roller.

  The image forming apparatus shown in FIG. 5 includes a drum-type electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 501 as an image carrier. The photosensitive drum 501 is obtained by providing a photosensitive layer made of an organic photoconductor (OPC) on the outer peripheral surface of a grounded cylindrical aluminum substrate. The photosensitive drum 501 is driven to rotate at a predetermined process speed (circumferential speed), for example, 50 mm / second, in the direction of arrow R1 by a driving means (not shown).

  The surface of the photosensitive drum 501 is uniformly charged by a charging device 502 as a contact charging member. The charging device 502 is disposed in contact with the surface of the photosensitive drum 501 and is driven to rotate in the direction of arrow R2 as the photosensitive drum 501 rotates in the direction of arrow R1. An oscillating voltage (AC voltage VAC + DC voltage VDC) is applied to the charging device 502 by a charging bias application power source (high voltage power source), whereby the surface of the photosensitive drum 501 is uniformly charged to −600 V (dark portion potential Vd). Is done. The surface of the charged photosensitive drum 501 is exposed to exposure means 503 such as laser light output from a laser scanner and reflected by a mirror, that is, laser light modulated in accordance with a time-series electric digital image signal of target image information. Scan exposure is performed. 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 501. The electrostatic latent image is reversely developed as a toner image by attaching negatively charged toner by a developing bias applied to the developing sleeve of the developing device 504.

  On the other hand, a transfer material 507 such as paper fed from a paper supply unit (not shown) is guided by a transfer guide (not shown), and a transfer unit (transfer) between the photosensitive drum 501 and the transfer roller 506. The toner image is supplied to the nip portion T in synchronization with the toner image on the photosensitive drum 501. The toner image on the photosensitive drum 501 is transferred onto the surface of the transfer material 507 supplied to the transfer portion T by a transfer bias applied to the transfer roller 506 by a transfer bias application power source. At this time, toner remaining on the surface of the photosensitive drum 501 without being transferred to the transfer material 507 (residual toner) is removed by the cleaning device 509.

  The transfer material 507 that has passed through the transfer portion T is separated from the photosensitive drum 501 and introduced into the fixing device 510, where the toner image is subjected to fixing processing, and is discharged out of the image forming apparatus main body as an image formed product (print). The

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

Table 1 shows the blending ratios and test results of the rubber compositions used in the examples and comparative examples. In addition, the unit of a compounding quantity is a mass part. In the present embodiment, the volume specific resistance value of the rubber composition is 10 ^7.0 to 10 ^7.8 Ω · cm based on the resistance value required for the conductive rubber roller for the color image forming apparatus. The formulation was adjusted.

  In this embodiment, a conductive rubber roller is manufactured as a transfer roller. However, it goes without saying that this conductive rubber composition is used for manufacturing a conductive rubber roller such as a charging roller, a developing roller, and a toner supply roller. Yes.

  First, the raw materials shown in Table 1 were kneaded with an open roll to prepare rubber compositions of the examples and comparative examples. In addition, the material used by each Example and the comparative example is as follows.

Epichlorohydrin rubber (Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer)
[Epichlorohydrin content 39 mol% / ethylene oxide content 56 mol% / allyl glycidyl ether content 5 mol%; trade name: Zeklon 3106 (manufactured by Nippon Zeon Co., Ltd.)]
Epichlorohydrin rubber (Epichlorohydrin-ethylene oxide binary copolymer)
[Zeospan 8100 (manufactured by Nippon Zeon Co., Ltd.)]
Ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer (ethylene oxide / propylene oxide / allyl glycidyl ether copolymer ratio = 90: 6: 4) [trade name: Zeospan 8030 (manufactured by Nippon Zeon Co., Ltd.)]
Ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer (ethylene oxide / propylene oxide / allyl glycidyl ether copolymer ratio = 87: 1: 12) [trade name: Zeospan 8010 (manufactured by Nippon Zeon Co., Ltd.)]
Acrylonitrile butadiene rubber (acrylonitrile content 18% by mass) [trade name: Nipol DN401LL (manufactured by Zeon Corporation)]
Carbon black [FT carbon; trade name: Asahi # 15 (Asahi Carbon Co., Ltd.)]
Filler [Calcium carbonate; trade name: Super SS (manufactured by Maruo Calcium Co., Ltd.)]
Vulcanization accelerator [stearic acid; trade name: LUNAC S (manufactured by Kao Corporation)]
[Zinc oxide; Trade name: Zinc flower 2 types (manufactured by Hakusuitec Co., Ltd.)]
Vulcanization accelerator [Mercaptobenzothiazole (M); Trade name: Noxeller M (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 (Ouchi Shinsei Chemical Co., Ltd.)]
Vulcanizing agent [Sulfur (S); trade name: Sulfax PMC (manufactured by Tsurumi Chemical Co., Ltd.)]
Foaming agent [Azodicarbonamide; trade name: VINYHALL AC # LQ (manufactured by Eiwa Kasei Co., Ltd.)]
[Oxybisbenzenesulfonyl hydrazide; trade name: Neoselbon # 1000S (manufactured by Eiwa Kasei Co., Ltd.)]
Foaming aid [Urea; trade name: Cell Paste A (manufactured by Eiwa Kasei Co., Ltd.)]

  In addition, the conductive rubber roller of an Example and a comparative example was produced as follows. First, after kneading said material with an open roll, the rubber composition was extruded to the tube shape using the extruder. This was vulcanized with a vulcanizer at the vulcanization temperature (160 ° C.) shown in Table 1 for 30 minutes to produce a tubular rubber vulcanizate. Next, a φ6 mm conductive shaft was inserted into the inner diameter of the tubular rubber vulcanizate to obtain a roller-shaped molded body. The molded body was polished so that the outer diameter was 14 mm to produce a conductive rubber roller.

<Measurement of roller volume resistivity>
The volume specific resistance value of the conductive rubber roller was measured as follows. First, the conductive rubber roller was left in an environment of 23 ° C./55 RH% for 24 hours. The shaft 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 sides, and the drum is rotated at a rotation speed of 30 rpm. A voltage of 1 kV was applied for 5 seconds. At this time, the roller resistance value was calculated from the current value detected by the multimeter according to Ohm's law.

<Compression set>
A test piece of solid rubber (excluding the foaming agent and foaming aid) was prepared in the formulation shown in Table 1, and the measurement temperature was 70 ° C. and the test time was 24 hours in accordance with the provisions of JIS K6262 “Permanent strain test method for vulcanized rubber”. The test was conducted. The determination was made according to the following criteria.

○: Within 35% ×: Over 35%

<Photoconductor contamination determination test>
This was performed using a conductive rubber roller molded and polished to 14 mm in diameter and 230 mm in length according to the blending of the examples and comparative examples. This was brought into contact with a photoreceptor used in a laser printer (Laser Jet 4000N (manufactured by HP)), a load of 500 gf was applied to both ends, and the mixture was left in an environment of 40 ° C./95% RH for 1 week. Thereafter, the roller was removed, the photoconductor was incorporated into the cartridge of the laser printer, and 30 sheets were printed in solid black to obtain an image. With respect to this image, a case where there was no white streak of the contact trace was determined as A, a case where a white streak was initially present but disappeared halfway, and a case where white streak did not disappear until the end was determined as C.

  In Examples 1 to 4, it can be seen that the compression set is good with low resistance and without contaminating the photoreceptor.

  On the other hand, in Comparative Example 1, when the main rubber component of the rubber composition was epichlorohydrin rubber alone, the compression set was increased.

  In Comparative Examples 2 and 3, the photosensitive drum was contaminated.

  Further, in Comparative Example 4, the compression set increased because the crosslinking density was small.

  Furthermore, in Comparative Example 5, the photosensitive drum was contaminated.

  As described above, according to the conductive rubber roller of the present invention, it can be seen that a conductive rubber roller having a low compression resistance and a good compression set without contaminating the photosensitive drum can be obtained.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments, various modifications and changes may be made to the embodiments without departing from the broad spirit and scope of the invention as defined in the claims. Obviously you can. In other words, the present invention should not be construed as being limited by the details of the specific examples and the accompanying drawings.

Overall cross-sectional view of a conductive rubber roller according to the present invention Schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller according to the present invention. Schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller according to the present invention Schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller according to the present invention 1 is a cross-sectional view of an entire image forming apparatus according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Primary charger 3 Exposure light 5 Intermediate transfer belt 6 Primary transfer roller 7 Secondary transfer roller 8 Secondary transfer counter roller 9 Cleaning charging member 10 Transfer material guide 11 Paper feed roller 12 Tension roller 13 Cleaning device 15 Fixing Device 16 Transfer conveyor belt 17 Transfer roller 18 Cleaning device 30 Bias power source 31 Bias power source 32 Primary charger power source 33 Bias power source 41 Yellow color developing device 42 Magenta color developing device 43 Cyan color developing device 44 Black color developing device 51 Photosensitive belt 52 Drive Roller 53 Followed roller 61 Core metal 62 Elastic layer 63 Adsorption roller 121 Conductive rubber roller 122 Ammeter 123 Drive roller 501 Photosensitive drum 502 Charging device 503 Exposure means 504 Development device 505 Toner 506 Transfer roller La 507 transfer material 508 cleaning blade 509 cleaning device 510 fixing device P transfer material R1 arrow R2 arrow T transfer unit

Claims (7)

A conductive rubber roller having a conductive core and an elastic layer provided on the conductive core,
The elastic layer is formed from epichlorohydrin rubber and an ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer,
The ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer is:
80 to 90 mol% of ethylene oxide;
Greater than 0 mol% and less than or equal to 10 mol% propylene oxide;
10 to 20 mol% of allyl glycidyl ether;
A copolymer consisting of
The ratio (b / a) of the mass part (b) of the ethylene oxide / propylene oxide / allyl glycidyl ether terpolymer to the mass part (a) of the epichlorohydrin rubber is:
0.05 ≦ b / a ≦ 1.0
A conductive rubber roller.   The conductive rubber roller according to claim 1, wherein the epichlorohydrin rubber is an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer.   The conductive rubber roller according to claim 1, wherein the conductive rubber roller is a transfer roller.   A process cartridge comprising the conductive rubber roller according to claim 1.   The process cartridge according to claim 4, wherein the conductive rubber roller is a transfer unit that transfers toner to a transfer material.   An image forming apparatus comprising the conductive rubber roller according to claim 1. The image forming apparatus according to claim 6, wherein the conductive rubber roller is a transfer unit that transfers toner to a transfer material.

Images