JP2009211003A - Conductive roller, method for manufacturing conductive roller, process cartridge and electrophotographic unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller which has sufficient conductivity, adhering strength and a barrier effect between a conductive shaft body and a conductive rubber elastic layer, is reduced in variation in resistance of the conductive roller and suppresses peeling of the conductive rubber elastic layer from the conductive shaft body after storage for a long period of time. <P>SOLUTION: The conductive roller has a conductive adhesive layer on an outer periphery of the conductive shaft body and at least one or more conductive rubber elastic layers comprising a rubber composition on the outer periphery of the conductive adhesive layer. The conductive adhesive layer includes the conductive adhesive containing carbon nano tube and binder resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a conductive roller, and more particularly to a conductive roller such as a charging roller in an image forming apparatus such as electrophotography.

  Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, the surface of an electrophotographic photosensitive member is uniformly charged, and an image is projected onto the electrophotographic photosensitive member from an optical system so that the portion is exposed to light. A latent image is formed by erasing the charge of the image. Next, a method of printing is performed by forming (developing) a toner image by toner adhesion and transferring the toner image onto a recording medium such as transfer paper.

  As a means for uniformly charging the surface of the electrophotographic photosensitive member, a charging roller to which a voltage is applied is brought into contact with the electrophotographic photosensitive member with a predetermined pressing force so as to charge the electrophotographic photosensitive member to a predetermined potential. A charging method is known. In the contact charging method using a charging roller, uniform contact with the electrophotographic photosensitive member, which is important for uniform charging, is made by a charging roller that is a rotating cylindrical body similar to the electrophotographic photosensitive member. It is easier to realize than other contact charging methods.

  Since the charging roller performs contact charging with the electrophotographic photosensitive member, when the charging roller is electrically non-uniform, uneven charging density reflecting the electric non-uniformity is generated. Therefore, the charging roller is required to have a predetermined resistance and be electrically uniform.

  As such a charging roller, for example, a low hardness conductive rubber elastic layer is provided on the outer peripheral surface of a predetermined conductive shaft body which is a conductor. Furthermore, a structure in which surface layers such as a resistance adjusting layer and a protective layer are sequentially laminated on the outer peripheral surface of the conductive rubber elastic layer by coating or the like is employed as necessary. In order to ensure uniform contact with an electrophotographic photosensitive member or the like, the charging roller is required to have good surface smoothness and high dimensional accuracy.

  In order to obtain this low hardness conductive rubber elastic layer, as a rubber composition of the conductive rubber elastic layer, a conductive filler such as carbon black is added to a polymer such as ethylene-propylene rubber and styrene-butadiene rubber, Furthermore, what added the softening agent is known. Further, in order to obtain a more electrically uniform conductive rubber elastic layer, rubber having a certain low resistance can be used. For example, a rubber composition using a polar rubber such as an acrylonitrile butadiene rubber (NBR), an epichlorohydrin rubber, a multi-polymer in which ethylene oxide / allyl glycidyl ether is copolymerized is used. Thereby, it is known that a conductive rubber elastic layer excellent in electrical uniformity can be obtained.

As a charging roller, a desirable resistance value between the conductive shaft and the surface is 10 ⁹ to 10 ¹¹ Ω, and a volume specific resistance of the conductive rubber elastic layer is 10 ⁵ to 10 ⁷ Ω · cm.

  As a method for producing a conductive roller, an unvulcanized rubber composition is extruded using an extruder, and at the same time, a conductive shaft body coated with an adhesive is passed through a crosshead die of the extruder to form a conductive shaft. An unvulcanized rubber composition is coated on the outer periphery of the body. Thereafter, a manufacturing method is known in which the conductive roller shape is adjusted by a grinding process of the conductive rubber elastic layer through a vulcanization process.

  By the way, these conductive rollers use a conductive adhesive (conductive adhesive) between the conductive shaft and the conductive rubber elastic layer. As the conductive adhesive, there is known a method using an adhesive added with carbon or the like in order to have conductivity (for example, Patent Document 1). However, if the conductivity of the conductive adhesive layer used between the conductive shaft body and the conductive rubber elastic layer is not sufficient, the resistance value of the conductive roller may increase or vary. In order to prevent this, a method of sufficiently adding a conductive component such as carbon to the conductive adhesive can be considered. However, if the addition amount of the conductive component is increased, the content of the binder resin for the conductive adhesive is reduced, so that sufficient barrier strength against humidity and humidity cannot be obtained. For this reason, after long-term storage (particularly high temperature and high humidity), the conductive rubber elastic layer may float or peel from the conductive shaft due to a decrease in adhesive strength or corrosion of the conductive shaft.

  In order to obtain sufficient adhesion, a method of applying a conductive adhesive thickly is known (for example, Patent Document 2). However, the method of thickly applying the conductive adhesive onto the conductive shaft is complicated, and it becomes difficult to control adhesion and production. Further, at the same time as extruding the unvulcanized rubber composition using an extruder, the conductive shaft coated with the conductive adhesive is passed through the crosshead die of the extruder to be placed on the outer periphery of the conductive shaft. In the step of coating the unvulcanized rubber composition, the conductive adhesive may adhere to the conductive shaft guide in the crosshead die, and the conductive shaft may be clogged in the guide. In order to prevent this, it is conceivable to increase the inner diameter of the conductive shaft guide. However, if the inner diameter of the conductive shaft guide is increased, the outer diameter accuracy of the conductive roller after extrusion is lowered, and a predetermined shape is obtained. For this reason, extrusion must be performed with a large outer diameter. For this reason, the tact time becomes longer in the subsequent polishing step, and the material cost may increase.

  Patent Document 3 discloses a method of preparing a conductive adhesive by using carbon nanotubes as conductive particles and mixing with a binder resin in order to obtain sufficient adhesion and conductivity. However, it shows that the conductive adhesive is used for bonding in a small area such as bonding of a piezoelectric vibrator, and does not mention the uniformity of conductivity in the conductive adhesive after coating.

Japanese Patent Laid-Open No. 10-293440 Japanese Patent Laid-Open No. 06-200921 JP 2004-27134 A

  An object of the present invention is to have a conductive adhesive layer on the outer periphery of a conductive shaft and a conductive rubber elastic layer made of at least one rubber composition on the outer periphery of the conductive adhesive layer. The conductive roller has sufficient conductivity, adhesive force, and barrier effect between the conductive shaft body and the conductive rubber elastic layer, exhibits uniform conductivity with small resistance variation of the conductive roller, and An object of the present invention is to provide a conductive roller capable of suppressing peeling of a conductive rubber elastic layer from a conductive shaft after long-term storage.

  In order to achieve the above object, the present invention has the following configuration.

  (1) A conductive roller having a conductive adhesive layer on the outer periphery of a conductive shaft, and having a conductive rubber elastic layer made of at least one rubber composition on the outer periphery of the conductive adhesive layer In the above, the conductive adhesive layer is composed of a conductive adhesive containing carbon nanotubes and a binder resin.

  (2) The conductive roller according to (1), wherein the content of the carbon nanotubes contained in the conductive adhesive layer is 1% by mass or more and 15% by mass or less.

  (3) The conductive roller according to (1) or (2), wherein the carbon nanotube is a carbon nanotube produced by a gas phase synthesis method.

  (4) The conductive roller according to any one of (1) to (3), wherein the conductive rubber elastic layer includes epichlorohydrin rubber.

  (5) The conductive roller according to any one of (1) to (4), wherein the binder resin is a thermosetting resin composition containing at least a phenolic resin.

  (6) The uncured rubber composition is extruded using an extruder equipped with a crosshead die, and at the same time, the conductive shaft body having the conductive adhesive layer is passed through the crosshead die and the conductive The conductive material according to any one of (1) to (5), wherein a vulcanization step is performed after the unvulcanized rubber composition is coated on the outer periphery of a conductive shaft body having an adhesive layer. It is a manufacturing method of a roller.

  (7) In the process cartridge that integrally supports one or both of the electrophotographic photosensitive member, the charging roller, the developing unit, and the cleaning unit and is detachable from the main body of the electrophotographic apparatus, (5) A process cartridge using the conductive roller according to any one of (5).

  (8) An electrophotographic apparatus having an electrophotographic photosensitive member, a charging roller, an exposure unit, a developing unit, and a transfer unit, wherein the process cartridge used in the electrophotographic apparatus is the process cartridge described in (7). An electrophotographic apparatus.

  The conductive roller of the present invention has sufficient adhesive force, conductivity, and barrier effect between the conductive shaft and the conductive rubber elastic layer, and exhibits uniform conductivity with small resistance variation of the conductive roller. . In addition, the conductive rubber elastic layer does not peel from the conductive shaft after long-term storage.

  The conductive roller of the present invention has a conductive adhesive layer on the outer periphery of a conductive shaft body, and a conductive rubber elastic layer made of at least one rubber composition on the outer periphery of the conductive adhesive layer. In the conductive roller having the above, the conductive adhesive layer is made of a conductive adhesive containing carbon nanotubes and a binder resin.

  That is, by using carbon nanotubes as the conductive component of the conductive adhesive layer, sufficient conductivity can be obtained even when the amount added is smaller than that of normal conductive carbon. This is because carbon nanotubes are more conductive than ordinary conductive carbon. By using carbon nanotubes, the amount of conductive component added can be reduced, and the content of the binder resin in the conductive adhesive layer can be increased. Therefore, the adhesive force can be increased, and the barrier effect against humidity etc. is also large. Therefore, after long-term storage (especially high temperature and high humidity), the adhesive force decreases and the conductivity from the conductive shaft due to the corrosion of the conductive shaft. It is possible to prevent the rubber elastic layer from peeling off.

[carbon nanotube]
The content of carbon nanotubes contained in the conductive adhesive layer is preferably 1% by mass or more and 15% by mass or less.

  This is because the conductivity of the conductive adhesive layer can be sufficiently obtained when the carbon nanotube content in the conductive adhesive layer is 1% by mass or more and 15% by mass or less. If the carbon nanotube content is less than 1% by mass, sufficient conductivity may not be obtained, and the resistance of the produced conductive roller may vary. On the other hand, when the content of the carbon nanotube is larger than 15% by mass, the content of the binder resin in the conductive adhesive layer is lowered, so that sufficient adhesive force cannot be obtained. For this reason, when the produced conductive roller is stored for a long period of time, the conductive rubber elastic layer and the conductive shaft body may be peeled off and the roller shape may be deformed. Moreover, since carbon nanotubes are excellent in electrical conductivity, it is difficult to further reduce the electrical resistance even if the content is increased from 15% by mass.

  The carbon nanotubes are preferably carbon nanotubes produced by a gas phase synthesis method.

  Known methods for producing carbon nanotubes include arc discharge, laser ablation, and gas phase synthesis. Carbon nanotubes produced by arc discharge and laser ablation methods are not preferred because they are very small in production and expensive. On the other hand, carbon nanotubes produced by a gas phase synthesis method are preferable because they have a relatively large production amount, are relatively inexpensive, and can be purchased stably.

  The carbon nanotube may be either a single wall nanotube (SWNT) made of a single carbon layer or a multi-wall nanotube (MWNT) made of a plurality of carbon layers.

  The carbon nanotube may have any shape such as a needle shape, a coil shape, a tube shape, or a cup shape. Specific examples include graphite whisker, filamentous carbon, graphite fiber, ultrafine carbon tube, carbon tube, carbon fibril, carbon microtube, and carbon nanofiber. These types of carbon nanotubes can be used alone or in combination of two or more.

[Binder resin]
Examples of the binder resin include phenol resin, furan resin, xylene / formaldehyde resin, and ketone / formaldehyde resin. These may be used alone or in combination of two or more.

  Among these, it is more effective when the binder resin is a thermosetting resin composition. The conductive roller extrudes the unvulcanized rubber composition using an extruder, and at the same time passes the conductive shaft through the crosshead die of the extruder to unvulcanized rubber on the outer periphery of the conductive shaft. After coating the composition, it can be produced through a vulcanization process. At this time, depending on the extrusion conditions, the temperature of the conductive shaft may become high when passing through the conductive shaft guide in the crosshead die. When the binder resin is a thermoplastic resin composition, the conductive adhesive melts by heat in the crosshead die and adheres to the inside of the conductive shaft guide, or the conductive adhesive peels off from the conductive shaft. There is a case. On the other hand, if the binder resin is a thermosetting resin composition, the conductive adhesive is not melted even at high temperatures and the strength of the conductive adhesive is maintained. Can be prevented from sticking or peeling off.

  The thermosetting resin composition is preferably a thermosetting resin composition containing at least a phenolic resin from the viewpoints of curability and adhesiveness.

  Although it does not specifically limit as a thermosetting resin composition containing the said phenol-type resin, The thermosetting resin composition containing phenol-type resins, such as alcohol solution type, aqueous solution type, and novolak type, which have phenol and formaldehyde as main components Can be used. Commercially available adhesives can also be used.

[Conductive adhesive]
The conductive adhesive for forming the conductive adhesive layer is obtained by dispersing the carbon nanotubes in at least one solvent in advance, and mixing the solvent in which the carbon nanotubes are dispersed with the binder resin separately dissolved in the solvent. It is preferable to prepare.

  Since it is difficult to disperse the carbon nanotubes as they are in the binder resin, for example, surface treatment such as oxidation treatment is performed to improve the compatibility with the solvent and disperse in the solvent. Thereafter, the dispersion of the carbon nanotubes can be made uniform by mixing with a binder resin separately dissolved in a solvent.

  As the method for dispersing the carbon nanotubes, various stirring methods such as normal stirring using a rotary blade or stirring using a magnetic stirrer, and stirring using an ultrasonic disperser may be used. it can. Among these, stirring using an ultrasonic disperser is preferable in that carbon nanotubes can be satisfactorily stirred without forming aggregates.

  The solvent for dispersing the carbon nanotubes is not particularly limited, and examples thereof include methyl isobutyl ketone and methyl ethyl ketone. These may be used alone or in admixture of two or more in a range where they are not separated.

  Examples of the solvent for dissolving the binder resin include methyl isobutyl ketone and methyl ethyl ketone. These may be used alone or in admixture of two or more in a range where they are not separated.

  The method for applying the conductive adhesive to the conductive shaft body is not particularly limited. For example, a method in which a conductive shaft having both ends chucked is rotated in the circumferential direction, and a silicone rubber sponge, acrylic rubber sponge or urethane rubber sponge impregnated with a conductive adhesive is pressed against the conductive shaft. Is mentioned. Moreover, you may use apparatuses, such as a roll coater, if it can apply | coat also to the both ends of a conductive shaft. Further, the concentration of the conductive adhesive may be applied by diluting to a predetermined concentration as long as it has sufficient adhesive force required as a member used in the manufacturing process and in the electrophotographic apparatus.

[Conductive shaft]
The conductive shaft body is made of a metal such as iron, copper and stainless steel, a carbon dispersion resin, a metal or a metal oxide dispersion resin having a columnar or cylindrical shape. Can be used. In addition, these surfaces may be subjected to plating treatment such as nickel plating for the purpose of providing rust prevention and scratch resistance.

[Conductive rubber elastic layer]
As the rubber composition for forming the conductive rubber elastic layer, a known rubber composition can be used. However, since a conductive rubber elastic layer having low hardness and low resistance can be obtained, epichlorohydrin rubber is used. It is preferable to use it.

  However, if chlorine atoms are contained like epichlorohydrin rubber, when stored in a high temperature and high humidity environment, the hygroscopic property increases, so rust is generated in the conductive shaft part and the roller shape is distorted. A normal image may not be obtained.

  Therefore, if carbon nanotubes are used as the conductive component contained in the conductive adhesive layer, sufficient conductivity can be obtained even when the content of the conductive component is low. For this reason, the ratio of the resin for binders in a conductive adhesive layer can be increased, and it is possible to improve the adhesive effect. In addition, the function of protecting the conductive shaft body from chlorine can be provided, and it is possible to prevent adhesion failure and corrosion of the conductive shaft body even under an environment such as high temperature and high humidity.

  In addition to the rubber composition forming the conductive rubber elastic layer, a conductive filler, an anti-aging agent, a softening agent, a plasticizer, a reinforcing agent, a filler and the like may be blended as necessary. Examples of the conductive filler to be blended as necessary include graphite, carbon black, and metal oxide. Examples of the metal oxide include titanium oxide and zinc oxide.

  The conductive rubber elastic layer is not limited to one layer, and may be composed of a plurality of conductive rubber elastic layers having different performance and thickness as required.

[Method of manufacturing conductive roller]
The manufacturing method of the conductive roller in the present invention is not particularly limited, but at the same time that the unvulcanized rubber composition is extruded using an extruder, the conductive shaft having the conductive adhesive layer is simultaneously extruded. Pass the crosshead die. After that, it is more effective to produce the vulcanized step after coating the uncured rubber composition on the outer periphery of the conductive shaft having the conductive adhesive layer.

  The conductive adhesive layer containing carbon nanotubes is excellent in conductivity, and also has excellent adhesiveness because of a large proportion of binder resin. For this reason, even if the thickness of the conductive adhesive layer applied to the conductive shaft body is reduced, it is possible to obtain sufficient conductivity and adhesive force. When normal conductive carbon is used as the conductive component of the conductive adhesive layer, it is necessary to thicken the conductive adhesive layer applied to the conductive shaft to some extent in order to obtain a sufficient adhesive force. In this case, the conductive shaft body having the conductive adhesive layer is passed through a crosshead die of an extruder, and an unvulcanized rubber material is coated on the outer periphery of the conductive shaft body having the conductive adhesive layer. In this process, the conductive adhesive may adhere to the inside of the conductive shaft guide in the crosshead die, and the conductive shaft may be clogged in the guide.

  Further, if the inner diameter of the conductive shaft guide is increased in order to prevent this, the outer diameter accuracy of the conductive roller after extrusion is lowered, and in order to obtain a predetermined shape, extrusion must be performed with a larger outer diameter. In this case, the tact time becomes longer in the subsequent polishing step, and the material cost may increase.

  On the other hand, the conductive adhesive layer containing carbon nanotubes is excellent in conductivity, and also has high adhesiveness because the ratio of the binder resin is high. For this reason, even if the thickness of the conductive adhesive layer applied to the conductive shaft body is reduced, sufficient conductivity and adhesive force can be obtained, and the conductive shaft body guide inner diameter in the crosshead die can be obtained. The outer diameter of the conductive shaft can be made with high accuracy, and the outer diameter of the conductive roller after extrusion can be made with high accuracy.

  Although the extruder provided with the said cross head die is not specifically limited, As an example, the extruder provided with the cross head die shown in FIG. 1 can be used.

  The extruder having the crosshead die shown in FIG. 1 includes a crosshead die 10 and an extruder 2. The crosshead die 10 includes an annular flow path 13 composed of an outer die 11 and an inner die 12.

  Hereinafter, as an example of the method for producing a conductive roller of the present invention, a method for producing a conductive roller using an extruder equipped with the crosshead die of FIG. 1 will be described in detail. It is not limited.

  In FIG. 1, the rubber composition 3 introduced into the inlet 5 of the extruder 2 is conveyed to the outlet 8 while being plasticized and kneaded by being subjected to shearing force in the cylinder 6 by the cylinder 6 and the screw 7. Is done. Subsequently, it passes through the breaker plate 9 and is conveyed to the rubber composition inlet 14 of the crosshead die 10. The rubber composition 3 hits the inner die 12 and splits into two hands, wraps around the inner die 12 and merges again at a portion opposite to the extruder side of the inner die 12. Subsequently, the rubber composition 3 flows in the direction of the die lip 15 via the annular flow path 13. The conductive shaft body 1 is extruded in the direction of the die lip 15 at a predetermined speed by the conductive shaft body guide 16 in the crosshead die 10, and the rubber composition 3 is coated on the conductive shaft body 1, and the conductive roller 4. It becomes.

  Thereafter, a desired conductive roller can be obtained through a vulcanization process in which the obtained conductive roller is vulcanized in a hot air furnace or the like.

[Surface layer]
The conductive roller of the present invention may have a surface layer on the outer periphery of the conductive rubber elastic layer in order to impart surface characteristics. The material for the surface layer is not particularly limited, and examples thereof include a surface layer material containing a urethane bond that is advantageous for conductive properties and abrasion resistance, and a resin having an acrylic skeleton that is advantageous for stain resistance.

  The method for forming the surface layer in the present invention is not particularly limited, but the resin composition constituting the surface layer is formed on the conductive rubber elastic layer using a method such as spray coating, dip coating, or roll coating. Apply to thickness. Thereafter, the surface layer can be formed on the conductive elastic layer by drying and curing at a predetermined temperature.

  Further, irregularities may be formed on the surface of the conductive roller. For example, as a method for forming irregularities, there are a method in which resin particles, carbon particles, silicon acid particles, metal oxide particles and the like are included in the surface layer, and a method in which the surface of the conductive roller is treated by mechanical polishing or the like. In addition, various particles, powders, and the like may be used alone or in combination of two or more for improving the image on the surface layer.

[Process cartridge]
The process cartridge of the present invention integrally supports one or both of an electrophotographic photosensitive member, a charging roller, a developing unit, and a cleaning unit, and is detachably attached to the main body of the electrophotographic apparatus. It comprises. An example of an embodiment of a process cartridge including the conductive roller of the present invention as a charging roller is shown in FIG. As described above, the process cartridge of the present invention comprises the conductive roller of the present invention. The electrophotographic photosensitive member, the exposure means, the developing means, the transfer means, the cleaning means, etc. It is not limited.

  In the process cartridge of the embodiment shown in FIG. 2, the electrophotographic photoreceptor 19 is rotationally driven in the direction of the arrow at a predetermined peripheral speed. In the rotation process, the electrophotographic photosensitive member 19 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by a charging roller 17 as a primary charging unit. Next, the image exposure 20 from image exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 19.

  The formed electrostatic latent image is then developed with toner by the developing means 21, and the developed toner image is synchronized with the rotation of the electrophotographic photoreceptor 19 between the electrophotographic photoreceptor 19 and the transfer means 22, The transfer means 22 sequentially transfers the transfer material 23 fed from a paper supply unit (not shown).

  The transfer material 23 that has received the image transfer is separated from the surface of the electrophotographic photosensitive member 19, introduced into the image fixing means 24, subjected to image fixing, and discharged out of the apparatus as a copy (copy).

  The surface of the electrophotographic photosensitive member 19 after the image transfer is cleaned by the cleaning unit 25 after the transfer residual toner is removed, and is repeatedly used for image formation.

  In the above example, the charging roller 19 is used. However, the roller according to the present invention corresponds to the developing roller provided in the developing means 21, the transfer roller provided in the transferring means 22, and the developing roller in the developing means 21. It can also be used for a developer regulating roller provided in contact therewith.

[Electrophotographic equipment]
The electrophotographic apparatus of the present invention is not particularly limited as long as it has the conductive roller of the present invention as a charging roller, a transfer roller, or a developing roller, and the process cartridge may be used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited only to these Examples.

Example 1
A dispersion (A) in which 10 parts by mass of carbon nanotubes (trade name: “CNF-T”, manufactured by Gemco Co., Ltd.) was preliminarily dispersed in 90 parts by mass of methyl isobutyl ketone was prepared. 2 parts by mass of the dispersion (A) and a vulcanized adhesive containing a phenolic resin as a binder resin to which no conductive particles are added (trade name: “Metaloc N-23”, Toyo Chemical Laboratory Co., Ltd.) 100 parts by mass (non-volatile content: 20%) were mixed. As a result, a conductive adhesive having 1% by mass of carbon nanotubes after application and drying of the conductive adhesive was produced.

  Using a roll coater on a conductive shaft body obtained by applying KN plating to a SUM (sulfur composite free-cutting steel material) with an outer diameter of φ6 mm preheated to 80 ° C., the film thickness is 5 to 10 μm. Then, it was baked at 180 ° C. for 5 minutes.

  Next, the following compounds were kneaded to prepare an unvulcanized rubber composition.

Epichlorohydrin rubber (trade name: “Epion 301”, manufactured by Daiso Corporation) 100 parts by mass Zinc oxide (trade name: “Zinc Hana 2”, manufactured by Hakusui Tech Co., Ltd.) 5 parts by mass Stearic acid (trade name: “Stearic acid S” manufactured by Kao Corporation 1 part by weight Calcium carbonate (trade name: “Silver W”, manufactured by Shiroishi Kogyo Co., Ltd.) 90 parts by weight FEF grade carbon black (trade name: “Asahi # 60”) Asahi Carbon Co., Ltd.) 5 parts by weight Ion conductive material (trade name: “LV-70”, Asahi Denka Kogyo Co., Ltd.) 2 parts by weight Polyester plasticizer (trade name: “PN-350”, Adeka Argus) 5 parts by mass dibenzothiazyl disulfide (MBTS) (trade name: “Noxeller DM”, manufactured by Ouchi Shinko Chemical Co., Ltd.) 1 part by mass tetramethylthiuram monosulfide (TMTM) (trade) Name: "NOCCELER TS", Ouchi made promotion Chemical Industry Co., Ltd.) 1 part by weight sulfur: manufactured (trade name "monkey fax PMC", Tsurumi Chemical Industry Co., Ltd.) 0.8 parts by weight.

  Next, the unvulcanized rubber composition was extruded together with the conductive shaft previously coated with the conductive adhesive using an extruder with a φ70 mm crosshead die so that the outer diameter was about φ13 mm. Was coated with an unvulcanized rubber composition. At this time, the extrusion speed of the rubber was continuously supplied at a constant speed of 2.5 m / min with a screw rotation speed of 14 rpm and a conductive shaft feed speed of 2.5 m / min. The inner diameter of the conductive shaft guide in the crosshead die was φ6.1 mm. This molded body was vulcanized in an electric furnace at 170 ° C. for 1 hour, and set in a polishing machine equipped with a polishing stone “GC80” (trade name, manufactured by Tsugami Corporation). Grinding was performed so that the outer diameter was 12 mm at a rotational speed of 2000 rpm and a feed speed of 0.3 m / min, and a conductive roller was prepared.

(Example 2)
Conductivity obtained by mixing 10 parts by mass of the dispersion (A) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)). A conductive adhesive having a carbon nanotube content of 5% by mass after applying and drying the adhesive was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Example 3)
Conductive adhesion in which 30 parts by mass of the dispersion (A) and 100 parts by mass of a vulcanized adhesive (trade name: “Metallock N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)) were mixed. A conductive adhesive having a carbon nanotube content of 15% by mass after coating and drying of the agent was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

Example 4
A conductive material obtained by mixing 1.0 part by mass of the dispersion (A) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)). A conductive adhesive having a carbon nanotube content of 0.5 mass% after applying and drying the conductive adhesive was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Example 5)
Conductive adhesion in which 40 parts by mass of the dispersion (A) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)) were mixed. A conductive adhesive having a carbon nanotube content of 20% by mass after coating and drying of the agent was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 1)
A dispersion (B) was prepared in which 10 parts by mass of acetylene black (trade name: “DENKA BLACK”, manufactured by Denki Kagaku Kogyo Co., Ltd.) was preliminarily dispersed in 90 parts by mass of methyl isobutyl ketone. 10 parts by mass of the dispersion (B) and a vulcanized adhesive to which no conductive particles are added (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory, Inc. (nonvolatile content 20%)) 100 mass A conductive adhesive in which the content of acetylene black after mixing and drying the conductive adhesive was 5% by mass was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 2)
Conductive bonding in which 40 parts by mass of the dispersion (B) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)) were mixed. A conductive adhesive having an acetylene black content of 20% by mass after coating and drying of the agent was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 3)
Conductive adhesion obtained by mixing 60 parts by mass of the dispersion (B) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)). A conductive adhesive having a content of acetylene black of 30% by mass after coating and drying of the agent was used. Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 4)
Conductive adhesion obtained by mixing 60 parts by mass of the dispersion (B) and 100 parts by mass of a vulcanized adhesive (trade name: “Metaloc N-23”, manufactured by Toyo Chemical Laboratory Co., Ltd. (nonvolatile content: 20%)). A conductive adhesive having a content of acetylene black of 30% by mass after coating and drying of the agent was prepared. This conductive adhesive is preheated to 80 ° C. and a SUM (sulfur composite free-cutting steel) material with an outer diameter of φ6 mm is subjected to KN plating on a conductive shaft body, and a roll coater is used to make the film thickness 20 to 25 μm. A conductive adhesive was applied so that Otherwise, the molding was performed in the same manner as in Example 1 to produce a conductive roller.

[Evaluation]
<Measurement of roller current value>
The current of the conductive roller was measured at an applied voltage of 200 V while contacting each of the 50 conductive rollers obtained in Examples and Comparative Examples with the SUS drum at 30 revolutions per minute. From the maximum current value and the minimum current value in the circumferential direction of the conductive roller, [current value unevenness] = (maximum current value) / (minimum current value) was calculated.

  Also, among the 50 conductive rollers that have been measured, the average current value of the conductive roller having the largest average current value is defined as the current value max, and the average current value of the conductive roller having the smallest average current value is represented by The current value was min. The average value of 50 of the average current value of one conductive roller was defined as the current value ave.

<Long-term storage peeling evaluation>
Fifty conductive rollers were left in an environment of high temperature and high humidity (45 ° C., 90%) for one week, and then the conductive rubber elastic layer of the conductive roller was peeled off to confirm the degree of adhesion. The ease of peeling after long-term storage was evaluated by the number of conductive rollers from which the conductive rubber elastic layer was easily peeled.

[Image evaluation]
Surface layers as shown below were applied to the conductive rollers obtained in Examples and Comparative Examples.

Acrylic polyol solution (trade name: “PLACCEL DC2016”, manufactured by Daicel Chemical Industries, Ltd., 70% by weight of active ingredient, 30% by weight of xylene as a diluent solvent) 100 parts by weight Isocyanate A (IPDI) (trade name: “VESTANAT B1370”, Made by Degussa, 60% by mass of active ingredient, 15% by mass of n-butyl acetate and 25% by mass of xylene as diluent solvent) 40 parts by mass Isocyanate B (HDI) (trade name: “DURANATE TPA-B80E”, Asahi Kasei Chemicals 30 mass parts carbon black (trade name: “CS-Bk100Y”, manufactured by Toda Kogyo Co., Ltd.) 30 mass parts surface-treated titanium oxide (trade name) : "SMT-150IB", manufactured by Teica) 25 parts by mass PMMA tree Fat particles (trade name: “MAX-12”, manufactured by Sekisui Plastics Co., Ltd.) 50 parts by mass Modified dimethyl silicone oil (trade name: “SH28PA”, manufactured by Toray Dow Corning Silicone) 0.08 parts by mass Methyl isobutyl 400 parts by weight of ketone.

  The compound was stirred using a mixer to prepare a mixed solution. Subsequently, the mixed solution was subjected to dispersion treatment (treatment speed 500 ml / min) using a circulation type bead mill disperser to prepare a dip coating paint. The viscosity of this paint was 8.0 mPa · s. Thereafter, the cored bar of the conductive roller was held so as to be perpendicular to the surface of the coating solution, and the elastic layer of the conductive roller was immersed in the coating solution. At this time, a masking cap made of polyacetal was put on the end portion of the stainless steel support of the conductive roller immersed in the coating solution. Then, it was heat-cured at 160 ° C. for 1 hour with a batch hot air dryer to form a coating layer to obtain a charging roller.

  The conductive roller coated with the surface layer obtained as described above was mounted on an electrophotographic apparatus (trade name: “HP Color LaserJet 3000”, manufactured by Hewlett-Packard Company) as a charging roller. Images were taken out in an atmosphere at a temperature of 23 ° C. and a humidity of 55%, and the obtained images were visually observed for evaluation.

○: Image density unevenness was not confirmed Δ: Slight image density unevenness was confirmed ×: Image density unevenness occurred.

  From Examples 1 to 5, by using the conductive adhesive of the present invention, it is possible to suppress the variation in the current value in the circumferential direction of the conductive roller and the variation in the current value among the plurality of conductive rollers. A good image can be obtained with good reproducibility. Further, peeling between the conductive rubber elastic layer and the conductive shaft body due to long-term storage can also be suppressed.

  However, in Example 4, since the ratio of carbon nanotubes contained in the conductive adhesive after coating and drying was small, the current value circumferential unevenness was slightly increased, and slight image density unevenness was confirmed in the image evaluation. There was no problem in use.

  On the other hand, Comparative Example 1 and Comparative Example 2 using the conductive adhesive added with acetylene black could not obtain sufficient conductivity because the addition amount of acetylene black was small. Further, the current value max-min and the current value unevenness were larger than those of Examples 1 to 5, and image density unevenness occurred in the image evaluation.

  Further, in Comparative Example 3, no particular problem was observed in the current value max-min, the current value unevenness and the image evaluation, but sufficient adhesive force was not obtained due to the small ratio of the binder resin, and after long-term storage. Then, peeling of the conductive rubber elastic layer and the conductive shaft body was confirmed with 18 conductive rollers.

  Further, since Comparative Example 4 has a thick adhesive coating, the adhesive adheres to the inside of the conductive shaft guide in the extruder crosshead, and the conductive shaft is clogged in the conductive shaft guide. Conductive roller molding was stopped.

It is a cross-sectional schematic diagram of an example of the extruder which comprises a crosshead die. 1 is a diagram showing a schematic configuration of an electrophotographic apparatus equipped with a process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive shaft 2 Extruder 3 Rubber composition 4 Conductive roller 5 Input port 6 Cylinder 7 Screw 8 Discharge port 9 Breaker plate 10 Crosshead die 11 Outer die 12 Inner die 13 Annular flow path 14 Rubber composition inlet 15 Die lip 16 Conductive shaft guide 17 Charging roller 18 Power source 19 Electrophotographic photosensitive member 20 Image exposure 21 Developing means 22 Transfer means 23 Transfer material 24 Image fixing means 25 Cleaning means 26 Rail 27 Process cartridge

Claims (8)

Having a conductive adhesive layer on the outer periphery of the conductive shaft;
In the conductive roller having a conductive rubber elastic layer made of at least one rubber composition on the outer periphery of the conductive adhesive layer,
The conductive roller, wherein the conductive adhesive layer comprises a conductive adhesive containing carbon nanotubes and a binder resin.   The conductive roller according to claim 1, wherein the content of the carbon nanotubes contained in the conductive adhesive layer is 1% by mass or more and 15% by mass or less.   The conductive roller according to claim 1, wherein the carbon nanotube is a carbon nanotube manufactured by a gas phase synthesis method.   The conductive roller according to claim 1, wherein the conductive rubber elastic layer includes epichlorohydrin rubber.   The conductive roller according to claim 1, wherein the binder resin is a thermosetting resin composition containing at least a phenolic resin.   Extruding the unvulcanized rubber composition using an extruder equipped with a crosshead die, and simultaneously passing the conductive shaft having the conductive adhesive layer through the crosshead die, the conductive adhesive layer The conductive roller manufacturing method according to any one of claims 1 to 5, wherein a vulcanization step is performed after the unvulcanized rubber composition is coated on an outer periphery of a conductive shaft body having a surface. Method. In a process cartridge that integrally supports one or both of an electrophotographic photosensitive member, a charging roller, a developing unit, and a cleaning unit and is detachable from the main body of the electrophotographic apparatus,
6. A process cartridge using the conductive roller according to claim 1 as the charging roller. In an electrophotographic apparatus having an electrophotographic photosensitive member, a charging roller, an exposure unit, a developing unit, and a transfer unit,
An electrophotographic apparatus, wherein a process cartridge used in the electrophotographic apparatus is the process cartridge according to claim 7.

Images