JP2007293207A - Conductive rubber roller and primary transfer roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rubber roller and a primary transfer roller having low resistance and small environmental dependency of the resistance. <P>SOLUTION: A rubber component contained in a rubber composition constituting a rubber layer contains acrylonitrile-butadiene rubber (A), epichlorohydrin rubber (B) and an ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) satisfying the following conditions (1) to (3) so as to satisfy 0.1≤A/(A+B+C)≤0.9 and 0.01≤C/B≤2.0, wherein A, B and C represent parts by mass of the components (A), (B) and (C). Conditions (1) a copolymerization ratio of ethylene oxide: 80 to <90 mol%, (2) a copolymerization ratio of propylene oxide: >0 to 10 mol%, (3) a copolymerization ratio of allyl glycidyl ether: 10 to <20 mol%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductive 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 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. Further, a conductive rubber roller is used for each process such as charging and transfer around the photosensitive drum which is the center of image formation.

Conventionally, many electrophotographic image forming apparatuses employ a contact charging method that generates very little harmful ozone, and in particular, have excellent wear resistance and transfer material transportability at the transfer section. Roller-like members are mainstream. The roller-shaped member is made of an elastic material, and can reliably form a nip with respect to the intermediate transfer belt which is an image carrier. As a transfer roller that can achieve both electrical resistance and hardness, a conductive elastic body with a resistance of 1 × 10 ⁶ to 1 × 10 ¹⁰ [Ω] on a core metal such as SUS or Fe using carbon or ion conductive filler. A roller having a hardness of 20 to 40 degrees (ASKER-C) is used.

However, since the electrical resistance of the conductive rubber material thus obtained is affected by changes in the applied voltage, the resistance value varies depending on the dispersion state of the conductive filler in the rubber material, and the rubber having a stable resistance It was difficult to get the material. As a method for solving this problem, it is known to use acrylonitrile butadiene rubber or epichlorohydrin rubber as the main rubber component (Patent Document 1). By doing so, the resistance value becomes 1 × 10 ⁶ to 1 × 10 ¹⁰ [Ω] without adding a conductive filler such as carbon black. Therefore, there is no need to add a conductive filler, and it is known that the resistance value variation due to processing conditions and the like, and the resistance value variation due to applied voltage are small, making it suitable as a conductive rubber roller having a stable resistance value. .

Further, the volume resistivity required for the elastic layer of the conductive rubber roller is often 2 × 10 ⁹ Ω · cm or less. On the other hand, 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.

Therefore, the volume specific resistance of the vulcanizate is adjusted to a desired volume specific resistance by blending epichlorohydrin rubber, which is known to be about 1 × 10 ^{7 to} 3 × 10 ⁹ Ω · cm, with acrylonitrile butadiene rubber. The method is generally used (Patent Document 1).

  In recent years, there has been a demand for a conductive rubber roller having a lower resistance in order to cope with colorization and high image quality. For example, a method of using epichlorohydrin rubber alone or adding various ionic conductive agents such as a quaternary ammonium salt containing perchlorate ion or chloride ion is also used (Patent Document 2). However, in general, in the case of a conductive rubber roller using such a rubber elastic body, there is a problem in that the image quality changes depending on the use environment because the resistance value changes due to environmental fluctuations in temperature and humidity. In particular, epichlorohydrin rubbers are susceptible to humidity and have a problem of large environmental fluctuations in resistance.

  There is also a method of adding various ionic conductive agents such as a quaternary ammonium salt as a method of reducing the resistance value to the use region of the color primary transfer roller. However, when a large amount of ionic conductive agent is added, the ionic conductive agent using a solvent oozes out and accumulates on the surface of the primary transfer roller by energization. As a result, adhesive force with the intermediate transfer belt is generated, driving torque is increased, normal operation cannot be performed, and the rubber of the roller itself is peeled off due to the adhesive and accumulates, thereby causing an abnormal image. Absent.

  In order to solve this problem, it is also conceivable to coat the surface of the conductive rubber roller with a material having good releasability, or to use a powdered conductive agent that does not use a solvent. However, a high releasability material is generally high in cost, and a powdered conductive agent is not preferable as a solution because there is a knowledge that the durability of the roller is lowered.

  Therefore, as a method for solving the above problems, various methods of blending a predetermined amount of ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer with polar rubber such as acrylonitrile butadiene rubber and epichlorohydrin rubber have been tried. . Since the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer contains ether oxygen, it functions to stabilize metal cations in the polymer and lower the electrical resistance. In addition, the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer has high polarity, so it has excellent compatibility with other polar rubbers, and allyl glycidyl ether has an unsaturated bond, so that it can crosslink with other rubbers. Is possible. Therefore, unlike conductive agents such as quaternary ammonium salts, bleeding and photoreceptor contamination are unlikely to occur. The ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer does not contain a halogen element. For this reason, it has been reported that a rubber material having good compression set can be obtained without problems such as chlorine causing side reactions unlike epichlorohydrin rubber (Patent Document 3).

Moreover, it is reported that a conductive rubber roller having better current durability and environment dependency than a conventional conductive rubber roller can be obtained by blending a predetermined amount of ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer. (Patent Documents 4 and 5). As a conventional conductive rubber roller, there are a conductive rubber roller using a rubber composition in which acrylonitrile butadiene rubber and epichlorohydrin rubber are blended, and a conductive rubber roller using a rubber composition to which an ionic conductive agent is added.
JP 2002-287456 A JP 2000-17118 A JP 2002-105305 A JP 2002-296930 A JP 2004-269618 A

  However, although the conductive rubber roller blended with the above-mentioned ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer has excellent current durability, further improvement has been demanded with respect to environmental dependency.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method capable of reducing resistance without deteriorating belt adhesion, having good durability, and reducing environmental fluctuation. That is. The target conductive rubber roller is a conductive rubber roller using a polar rubber such as acrylonitrile butadiene rubber or epichlorohydrin rubber, such as a transfer roller, a charging roller or a developing roller.

  The object of the present invention is achieved by the following.

A conductive rubber roller in which a rubber layer is provided on a conductive core material, and the rubber components contained in the rubber composition constituting the rubber layer are acrylonitrile butadiene rubber (A), epichlorohydrin rubber (B), and An ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) that satisfies the following conditions (1) to (3):
0.1 ≦ A / (A + B + C) ≦ 0.9
0.01 ≦ C / B ≦ 2.0
(However, A, B, and C represent the mass part of a component (A), a component (B), and a component (C), respectively).
A conductive rubber roller characterized by being contained so as to satisfy.
(1) Copolymerization ratio of ethylene oxide: 80 mol% or more and less than 90 mol% (2) Copolymerization ratio of propylene oxide: more than 0 mol% and 10 mol% or less (3) Copolymerization ratio of allyl glycidyl ether: 10 mol% or more and 20 mol% The acrylonitrile butadiene rubber preferably has an acrylonitrile unit content of 15% by mass or more and 20% by mass or less, and a mass average molecular weight Mw of 10,000 or more.

The volume specific resistance value of the rubber composition constituting the rubber layer is preferably 10 ^7.0 Ω · cm or more and 10 ^8.5 Ω · cm or less in a 23 ° C./55 RH% environment.

  A primary transfer roller, which is the conductive rubber roller described above, in a primary transfer roller which is installed relative to a color image forming apparatus via a photoreceptor and an intermediate transfer belt.

  According to the above-described invention, it is possible to provide a conductive rubber roller that can reduce resistance without adding a substance that causes bleeding, and has a small resistance fluctuation in the environment.

  The conductive rubber roller of the present invention is excellent in that the resistance can be lowered without deteriorating the adhesion to the transfer belt, the durability is good, and the environmental dependency of the roller is small. Therefore, the conductive rubber roller of the present invention can transfer a transferable image by a toner image formed and supported by an image forming means such as an electrophotographic process or an electrostatic recording process on an image carrier such as an electrophotographic photosensitive member, a recording medium such as paper, It is suitable for a primary transfer roller of a transfer device that transfers to a transfer material.

  The conductive rubber roller of the present invention has a configuration in which a rubber layer 62 is provided on a conductive core member 61 as shown in FIG. This conductive rubber roller can be used as a charging roller, a developing roller, a toner supply roller, a transfer roller and the like provided in an image forming apparatus using an electrophotographic process. In particular, it is suitable as a primary transfer roller that is installed relative to a color image forming apparatus via a photoreceptor and an intermediate transfer belt.

  FIG. 2 shows a full-color image forming apparatus (copier or laser beam printer) using an electrophotographic process.

  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 power source for the primary charger. Here, alternating current is superimposed on direct current, but only direct current may be applied. Next, 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 formed by receiving exposure light 3 from an exposure unit (not shown). As the exposure means, 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 are used. .

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

  The intermediate transfer belt 5 is stretched by two rollers, a driving roller 8 and a tension roller 12, and is rotationally driven in the direction of the arrow with the same peripheral speed as that of the photosensitive drum 1.

  The first color yellow toner image 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 an electric field formed by a 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 the first to fourth color toner images from the photosensitive drum 1 to the intermediate transfer belt 5 is applied from a bias power source 30 with a polarity (+) 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 step 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 transferred onto the transfer material P as follows. First, the secondary transfer roller 7 is brought into contact with the intermediate transfer belt 5, and from the paper feed roller 11 through the transfer material guide 10 to a contact nip between the intermediate transfer belt 5 and the secondary transfer roller 7. The transfer material P is fed at the timing. A secondary transfer bias is applied from the bias power supply 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 5 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, the cleaning charging member 9 disposed so as to be detachable is brought into contact with the intermediate transfer belt 5. Then, by applying a bias having a polarity opposite to that of the photosensitive drum 1, 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. The Reference numeral 33 denotes a bias power source. Here, alternating current is superimposed on direct current and applied. The 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 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 cartridge of the present invention only needs to be configured so that at least the intermediate transfer belt 5, the electrophotographic photosensitive member 1, and the primary transfer means 6 are integrally supported and are detachable from the apparatus main body. In FIG. 3, an intermediate transfer belt cleaning mechanism 13 and an electrophotographic photosensitive member cleaning mechanism 9 are also attached as an integrated unit. As described above, the cleaning of the intermediate transfer belt of the present invention 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. A cleaning roller 9 made of a resistive elastic body is provided. Cleaning of the electrophotographic photosensitive member is blade cleaning. This cartridge also includes a waste toner container (not shown), and the transfer residual toner on both the intermediate transfer belt and the electrophotographic photosensitive member is also discarded at the same time when the cartridge is replaced, which contributes to improvement in maintainability. .

  Further, the intermediate transfer belt is stretched by two rollers of a driving roller 8 and a tension roller 12 to reduce the number of parts and reduce the size. Here, the driving roller 8 is simultaneously a counter roller of the cleaning roller. 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 electrophotographic photosensitive member 1 and the driving roller 8 have a coupling (not shown) so that a rotational driving force is transmitted from the main body.

  FIG. 4 shows another example of the image forming apparatus. FIG. 4 has the same number of electrophotographic photoreceptors 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.

  4 uses an intermediate transfer belt. As in FIG. 2, the visible image formed on the electrophotographic photosensitive member 1 is sequentially transferred to the intermediate transfer belt 5 and superimposed, and then the toner is transferred to the secondary transfer roller 7 by the secondary transfer roller 7. Are applied to the transfer material P in a batch. The developer remaining on the intermediate transfer belt 5 is removed by the cleaning device 18.

The present invention is a conductive rubber roller in which a rubber layer is provided on a conductive core material. And the rubber component contained in the rubber composition which comprises a rubber layer is acrylonitrile butadiene rubber (A), epichlorohydrin rubber (B), ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C), and Containing. Here, the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) is selected so as to satisfy the following conditions (1) to (3).
(1) Copolymerization ratio of ethylene oxide: 80 mol% or more and less than 90 mol% (2) Copolymerization ratio of propylene oxide: more than 0 mol% and 10 mol% or less (3) Copolymerization ratio of allyl glycidyl ether: 10 mol% or more and 20 mol% And each component contains so that the following conditions may be satisfied.

0.1 ≦ A / (A + B + C) ≦ 0.9
0.01 ≦ C / B ≦ 2.0
(However, A, B, and C represent the mass part of a component (A), a component (B), and a component (C), respectively).
Hereinafter, the conductive rubber roller of the present invention will be described in detail.

  The conductive core material used in the conductive rubber roller of the present invention is not particularly limited as long as it is a conductive core material. For example, a metal core material can be used.

The rubber layer formed on the outer periphery of the conductive core material is composed of a rubber composition containing a rubber component and other components used as necessary. The volume specific resistance value of the rubber composition constituting the rubber layer is preferably 10 ^7.0 Ω · cm or more and 10 ^8.5 Ω · cm or less in an environment of 23 ° C./55 RH%.

  The rubber composition contains acrylonitrile butadiene rubber (A), epichlorohydrin rubber (B), and ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) as rubber components.

  The acrylonitrile butadiene rubber as the component (A) is not particularly limited, and for example, commercially available acrylonitrile butadiene rubber can be used. Preferably, the acrylonitrile butadiene rubber has a content of acrylonitrile units of 15 to 20% by mass and a low nitrile, and further has a mass average molecular weight Mw of 10,000 or more. Those having a large amount of low molecular weight components such as liquid NBR are likely to cause bleeding and may accumulate on the back surface of the transfer belt and cause image defects. Further, when the content of acrylonitrile units is less than 15% by mass, it tends to be difficult to obtain a predetermined resistance value, and when the content of acrylonitrile units exceeds 20% by mass, the environmental dependency of resistance tends to increase. is there. The acrylonitrile butadiene rubber may be used alone or as a blend of two or more.

  The epichlorohydrin rubber as a component (B) is not specifically limited, For example, a commercially available epichlorohydrin rubber can be used. Specifically, epichlorohydrin homopolymer (ECH), epichlorohydrin-ethylene oxide copolymer (ECH-EO), epichlorohydrin-allyl glycidyl ether copolymer (ECH-AGE), and epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer A combination (ECH-EO-AGE) and the like are commercially available. Among these, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (ECH-EO-AGE) is preferable. Since epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer contains ethylene oxide, it has a lower volume resistivity, and since it contains allyl glycidyl ether, sulfur vulcanization is possible, thereby preventing contamination of the photoreceptor.

  Moreover, when epichlorohydrin rubber has an ethylene oxide unit, it is more preferable that the copolymerization ratio of ethylene oxide in the rubber is 38 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 smaller than 38 mol%, it is difficult to obtain the electric resistance value necessary for the rubber layer of the conductive rubber roller, the blending ratio of epichlorohydrin rubber is increased, and the environment dependency is increased. There is. More preferably, the copolymerization ratio of ethylene oxide in the epichlorohydrin rubber is 40 to 58 mol%. The epichlorohydrin rubber may be used alone or as a blend of two or more.

  The ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer as the component (C) is selected from those having an allyl glycidyl ether copolymerization ratio of 10 mol% or more and less than 20 mol%. Since the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer contains ether oxygen, it functions to stabilize metal cations in the polymer and lower the electrical resistance. Therefore, it is important that the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer used in the present invention has an allyl glycidyl ether copolymerization ratio of 10 mol% or more and less than 20 mol%. More preferably, it is 10-15 mol%. Further, since allyl glycidyl ether has an unsaturated bond, it can be crosslinked with other rubbers, and the molecular chain segmental motion is influenced by the copolymerization ratio of allyl glycidyl ether. Accordingly, when the copolymerization ratio of allyl glycidyl ether is less than 10 mol%, a conductive rubber roller excellent in current-carrying durability can be obtained, but since there are few crosslinking points, an ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer is obtained. The degree of freedom is too large. Therefore, the environment dependency is not sufficient particularly in a high temperature and high humidity environment, and there arises a problem that the image quality changes depending on the use environment. In addition, when the copolymerization ratio of allyl glycidyl ether is not appropriate, the resistance reduction due to ether oxygen is inhibited, or a significant resistance change occurs in a high-temperature and high-humidity environment where molecular motion is activated. Becomes larger. When the copolymerization ratio of allyl glycidyl ether is 20 mol% or more, the number of crosslinking points is excessively increased, and the degree of freedom of ether oxygen in the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer is inhibited. Lowering the resistance becomes difficult. Furthermore, tensile properties, fatigue properties, bending resistance, etc. are deteriorated.

  The copolymerization ratio of ethylene oxide and propylene oxide in the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer used in the present invention is selected as follows from the viewpoints of compatibility, electrical resistance value and the like. The copolymerization ratio of ethylene oxide is 80 mol% or more and less than 90 mol%, and the copolymerization ratio of propylene oxide is selected from more than 0 mol% and 10 mol% or less.

  The blending amount of the acrylonitrile butadiene rubber (A) used in the present invention is 0.1 to 0.9 parts by mass with respect to a total of 1 part by mass of the component (A), the component (B) and the component (C). .

  The blending mass of the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) used in the present invention is 0.01 to 2.0 parts by mass with respect to the blending mass of the epichlorohydrin rubber (B). When the blending ratio is less than 0.01 parts by mass, it is difficult to sufficiently obtain the effects of low resistance and high durability by the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C). If this blending ratio exceeds 2.0 parts by mass, the environmental dependency of the resistance tends to increase, and the photoreceptor may be contaminated.

  In the present invention, a blend of ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C), acrylonitrile butadiene rubber (A) and epichlorohydrin rubber (B) containing allyl glycidyl ether units having a specific copolymerization ratio is used. To do. This blend balances the resistance change caused by the difference between the segmental motion of the molecular chain and the action of ether oxygen in the main chain structure to stabilize ions. And in addition to the low resistance which the conductive rubber roller containing the conventional ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer has, the resistance value in the environmental fluctuation | variation (especially between N / N-H / H environment). The change of can be reduced.

  Moreover, the rubber composition used for the conductive rubber roller of the present invention can contain other components used for general rubber as required. For example, vulcanizing agents such as sulfur and organic sulfur-containing compounds, various vulcanization accelerators, various processing aids such as lubricants and subs, various anti-aging agents, p, p'-oxybissulfonylhydrazide (OBSH) and azodicarbon Various foaming agents such as amide (ADCA) and dinitrosopentamethylenetetramine (DPT), various foaming aids such as urea, vulcanization aids such as zinc oxide and stearic acid, various types such as calcium carbonate, talc, silica and clay Fillers can be blended as needed. Various ionic conductive agents can also be blended as necessary for adjusting the conductivity. However, the transfer to the roller surface may contaminate the photosensitive member or accumulate on the back surface of the intermediate transfer belt, causing a problem in driving. Therefore, it is preferable to use less than 1 part by mass with respect to 100 parts by mass of the rubber component. preferable.

  The conductive rubber roller of the present invention can be obtained by the following manufacturing method, for example. First, an unvulcanized rubber composition is extruded into a tube shape by an extruder and heated in a vulcanizing can or a continuous vulcanizing furnace to produce a rubber (elastic body) tube. Then, after inserting a conductive core material coated with an adhesive into the rubber tube and further heating it, the conductive core material and the rubber tube are bonded together and then polished to a predetermined outer diameter. Thus, a conductive rubber roller can be obtained. Various conventionally known production methods such as co-extrusion of an unvulcanized rubber composition and a conductive core material coated with an adhesive and vulcanization by loading the extruded rubber composition into a mold can be applied. . Moreover, the conductive rubber roller of the present invention can be provided with a layer of resin or the like on the outer periphery of the rubber layer as necessary.

  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 compositions used in the examples and comparative examples. In addition, the unit of a compounding quantity is a mass part. In this embodiment, the composition was adjusted so that the volume specific resistance value of the rubber composition was 10 ^7.0 to 10 ^8.5 Ω · cm based on the roller resistance value required as the primary transfer roller of the color image forming apparatus. .

  In this embodiment, a conductive rubber roller is manufactured as a transfer roller. However, it goes without saying that the conductive rubber roller is used as a charging roller, a developing roller, a toner supply roller, or the like.

  First, the raw materials shown in Table 1 and Table 2 were kneaded with an open roll to prepare a rubber composition for forming a rubber layer of the conductive rubber roller of each Example and Comparative Example.

In addition, the material used by each Example and the comparative example is as follows.
-Ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer [ethylene oxide-propylene oxide-allyl glycidyl ether copolymerization ratio = 90: 6: 4 (molar ratio), mass average molecular weight (Mw) 10,000 or more; Zeospan 8030; manufactured by Nippon Zeon Co., Ltd.]
[Ethylene oxide-propylene oxide-allyl glycidyl ether copolymerization ratio = 87: 1: 12 (molar ratio), mass average molecular weight (Mw) 10,000 or more]
Acrylonitrile butadiene rubber [Acrylonitrile unit content 18% by mass; trade name Nipol DN401LL, manufactured by Nippon Zeon Co., Ltd.]
[Content of acrylonitrile unit: 31.5% by mass; trade name: Nipol DN223; manufactured by Nippon Zeon Co., Ltd.]
-Epichlorohydrin rubber [ethylene oxide content: 56 mol%; trade name Hydrin T3106; manufactured by Nippon Zeon Co., Ltd.]
・ Carbon black [FT carbon; trade name Asahi # 15; manufactured by Asahi Carbon Co., Ltd.]
・ Filler [Calcium carbonate; trade name Super SS; manufactured by Maruo Calcium Co., Ltd.]
・ Vulcanizing agent [Sulfur (S); trade name Sulfax PMC; manufactured by Tsurumi Chemical Co., Ltd.]
・ Vulcanization accelerator [Mercaptobenzothiazole (M); Product 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; manufactured by Ouchi Shinsei Chemical Co., Ltd.]
・ Vulcanization accelerating aid [Zinc oxide; Trade name: Zinc flower 2 types; manufactured by Hakusuitec Co., Ltd.]
[Stearic acid; trade name LUNAC S; manufactured by Kao Corporation]
-Foaming agent [p, p'-oxybissulfonyl hydrazide; trade name Neoselbon # 1000S; manufactured by Eiwa Kasei Co., Ltd.]
・ Foaming aid [Azodicarbonamide; trade name Binhol AC # LQ; manufactured by Eiwa Kasei Co., Ltd.]
[Urea; trade name Cell paste A; manufactured by Eiwa Kasei Co., Ltd.]
-Quaternary ammonium salt In addition, the conductive rubber roller of the Example and the comparative example was produced as follows. First, after extruding the rubber composition into a tube shape using an extruder, a vulcanized can is vulcanized at the vulcanization temperature described in Table 1 for 30 minutes to produce a tubular rubber vulcanizate, A φ6 mm conductive shaft was inserted into the inner diameter of the tubular rubber vulcanizate to obtain a roller-shaped molded body. This molded body was polished so as to have an outer diameter of 14 mm to obtain a conductive rubber roller.

<Volume specific resistance value>
A sheet having a thickness of 2 mm was prepared separately according to the formulation shown in Tables 1 and 2 (excluding the foaming agent and foaming aid). The sheet was allowed to stand for 24 hours in a 23 ° C./55% RH (N / N) environment, and then the applied voltage was 500 V with Hiresta (manufactured by Dia Instruments) in the same environment, and the volume was measured according to the method described in JIS K6911. The specific resistivity was measured.

<Roller resistance measurement (environment-dependent)>
The conductive rubber roller was pressed against a stainless steel drum having an outer diameter of 30 mm and rotated at 30 rpm so that a load of 500 g was applied to each side of the conductive core material of the manufactured conductive rubber roller. In this state, a voltage of 1000 V is applied between the conductive core material and the stainless steel drum, and 10 ° C / 15RH% (L / L), 23 ° C / 55% RH (N / N), and 32.5 The current value was measured under an environment of ° C / 95% RH (H / H), and the resistance value was calculated according to Ohm's law. The measured L / L resistance value was divided by the H / H resistance value, and logarithmically converted to obtain a variable digit. In this example and the comparative example, the fluctuation digits of the resistance value were evaluated based on the following evaluation criteria. In Tables 1 and 2, in addition to the above-mentioned fluctuation digits (L / L-H / H), the L / L resistance value is divided by the N / N resistance value and logarithmically converted fluctuation digits (L / L L-N / N) and N / N resistance values are divided by H / H resistance values and logarithmically converted fluctuation digits (N / N-H / H) are also shown.
○: Environmental change digits ≤ 1.6 (low environmental dependency)
×: 1.6 <Environmental change digits (high environmental dependence)
<Durability test>
A conductive rubber roller molded and polished to a diameter of 14 mm and a length of 230 mm was set as a transfer roller in an ITB unit of a color laser printer (trade name: Color Laser Jet 3500N; manufactured by HP). The main body was continuously energized and idled for 144 h while applying a voltage of 2.0 kV to the transfer roller in an L / L environment. After the test was completed, the roller resistance was measured after being left in the same environment for 24 hours, and the fluctuation digit from the resistance value before the test was calculated.

<Belt stickiness>
A conductive rubber roller molded and polished to a diameter of 14 mm and a length of 230 mm was set as a transfer roller in an ITB unit of a color laser printer (trade name: Color Laser Jet 3500N; manufactured by HP). Then, the main body was continuously energized idling for 72 hours while applying a voltage of 3.5 kV to the transfer roller in a J / J environment. Thereafter, intermittent idle rotation of 24 h (repetition of ON → OFF every 1 h) was performed. After the completion, the ITB unit was disassembled after being allowed to stand for 24 hours, and the adhesion level between the belt and the transfer roller was observed.

  As for the level of sticking, AA was not attached to the transfer belt at all, A was slightly sticky, and B was attached but was removed from the transfer belt by the weight of the roller. The thing which showed sticking was set to C. The levels applicable to the product are AA, A, and B, and the level of C is not possible.

  Examples 1 to 4 show that the conductive rubber roller that satisfies the conditions of the present invention can reduce resistance while suppressing a change in resistance value due to environmental fluctuations, and that the adhesion to the intermediate transfer belt is slight. (See Table 1).

比較例１はアクリロニトリルブタジエンゴム（Ａ）のみでゴム層を形成したとき、耐久性が悪くなってしまうことを示した事例である。

Comparative Example 1 is an example showing that when the rubber layer is formed only with acrylonitrile butadiene rubber (A), the durability is deteriorated.

  The comparative example 2 is an example which shows that an environmental fluctuation will become large when the copolymerization ratio of the allyl glycidyl ether in an ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer is less than 10 mol%.

  Comparative Example 3 is a case where the ratio (C / B) of epichlorohydrin rubber (B) to ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) exceeds 2.0 in the rubber component of the rubber composition This is an example that shows that environmental fluctuations become large.

  Comparative Example 4 is an example showing that the level of sticking to the transfer belt is poor when a rubber component not containing the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) is used. This sticking is caused by bleeding of the low molecular weight component onto the roller surface.

  In Comparative Example 5, when a quaternary ammonium salt was added as a conductive agent to the rubber composition without containing the ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C), the film was stuck to the transfer belt. This is an example that shows that the level of badness gets worse. This sticking is due to the quaternary ammonium salt being transferred to the roller surface by energizing the roller.

以上に示したように、本発明の条件を満たすことで、ベルト貼りつきを悪化させることなく低抵抗化することができ、且つ耐久性も良好で環境変動も小さい導電性ゴムローラが得られることがわかる。

As described above, by satisfying the conditions of the present invention, it is possible to reduce the resistance without deteriorating the sticking of the belt, and it is possible to obtain a conductive rubber roller with good durability and small environmental fluctuation. Recognize.

1 is an external view of a conductive rubber roller according to the present invention. 1 is a schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller according to the present invention. 1 is a schematic configuration diagram of a process cartridge for a full color image forming apparatus using a conductive rubber roller according to the present invention. 1 is a schematic configuration diagram of a full-color image forming apparatus using a conductive rubber roller 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 Feed roller 12 Tension roller 13 Cleaning device 15 Fixing Device 18 Cleaning device 30, 31, 33 Bias power source 32 Primary charger power source 41 Yellow color developing device 42 Magenta color developing device 43 Cyan color developing device 44 Black color developing device 61 Conductive core material 62 Rubber layer P Transfer material

Claims (4)

A conductive rubber roller in which a rubber layer is provided on a conductive core material, and the rubber components contained in the rubber composition constituting the rubber layer are acrylonitrile butadiene rubber (A), epichlorohydrin rubber (B), and An ethylene oxide-propylene oxide-allyl glycidyl ether terpolymer (C) that satisfies the following conditions (1) to (3):
0.1 ≦ A / (A + B + C) ≦ 0.9
0.01 ≦ C / B ≦ 2.0
(However, A, B, and C represent the mass part of a component (A), a component (B), and a component (C), respectively).
A conductive rubber roller characterized by being contained so as to satisfy.
(1) Copolymerization ratio of ethylene oxide: 80 mol% or more and less than 90 mol% (2) Copolymerization ratio of propylene oxide: more than 0 mol% and 10 mol% or less (3) Copolymerization ratio of allyl glycidyl ether: 10 mol% or more and 20 mol% Less than   2. The conductive rubber roller according to claim 1, wherein the acrylonitrile butadiene rubber (A) has an acrylonitrile unit content of 15% by mass or more and 20% by mass or less and a mass average molecular weight Mw of 10,000 or more. 3. The volume specific resistance value of the rubber composition constituting the rubber layer is 10 ^7.0 Ω · cm or more and 10 ^8.5 Ω · cm or less in a 23 ° C./55 RH% environment. Conductive rubber roller.   4. The primary transfer roller installed relative to the image forming apparatus for color via the photosensitive member and the intermediate transfer belt, wherein the primary transfer roller is the conductive rubber roller according to claim 1. Transfer roller.

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