JP2009210699A - Conductive roller, manufacturing method for same, process cartridge, and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller having a sufficient adhesive force, conductivity and barrier effect between a conductive shaft body and a conductive rubber elastic layer, reduced in resistance dispersion of the conductive roller, exhibiting uniform conductivity, and capable of restraining the conductive rubber elastic layer from being separated out of the conductive shaft body, after stored for a long period. <P>SOLUTION: A conductive adhesive layer contains at least a conductive filler and a binder resin, in this conductive roller having the conductive adhesive layer on an outer circumference of the conductive shaft body, and having at least one layer or more of the conductive rubber elastic layers comprising a rubber composition, on an outer circumference of the conductive adhesive layer, and the conductive adhesive layer contains the conductive filler of ≥0.50 vol.% to ≤8.15 vol.%, in the conductive roller. <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.
Japanese Patent Laid-Open No. 10-293440 Japanese Patent Laid-Open No. 06-200921

  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 The conductive adhesive layer contains at least a conductive filler and a binder resin, and the conductive adhesive layer contains the conductive filler in an amount of 0.50% by volume to 8.15% by volume. This is a conductive roller.

  (2) The conductive roller according to (1), wherein the conductive filler is carbon black.

  (3) The conductive roller according to (1) or (2), wherein the binder resin is a thermosetting resin composition containing at least a phenolic resin.

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

  (5) 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 (4), wherein a vulcanization step is performed after coating the unvulcanized rubber composition on the outer periphery of a conductive shaft body having an adhesive layer. It is a manufacturing method of a roller.

  (6) 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, (4) A process cartridge using the conductive roller according to any one of (4).

  (7) 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 (6). 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. The conductive adhesive layer includes at least a conductive filler and a binder resin, and the conductive adhesive layer contains the conductive filler in an amount of 0.50% by volume or more, 8.15. It is an electroconductive roller characterized by containing below volume%.

  That is, by using the conductive adhesive layer containing at least a conductive filler and a binder resin, the ratio of the conductive filler contained is 0.50% by volume or more and 8.15% by volume or less. Conductivity can be obtained. Moreover, since the volume ratio of the conductive filler contained in the conductive adhesive layer is low, the ratio of the binder resin can be increased, and the adhesive force can be increased. In addition, since the barrier effect due to humidity, etc. is large, it can prevent the adhesion rubber elastic layer from being peeled off from the conductive shaft due to the decrease in adhesive strength or corrosion of the conductive shaft after long-term storage (especially high temperature and high humidity). Is possible.

  If the ratio of the conductive filler contained in the conductive adhesive layer is less than 0.50% by volume, sufficient conductivity may not be obtained, and the resistance of the manufactured conductive roller may vary. On the other hand, if the amount of the conductive filler to be added is larger than 8.15% by volume, the ratio of the binder resin in the conductive adhesive layer decreases, so that sufficient adhesive strength cannot be obtained. Furthermore, 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. A more preferable range of the ratio of the conductive filler contained in the conductive adhesive layer is 2.0% by volume or more and 6.0% by volume or less.

[Conductive filler]
Although there is no restriction | limiting in particular as a conductive filler contained in the said conductive adhesive layer, For example, carbon black, rubber, such as acetylene black, furnace black, and "Ketjen black" (trade name, product made from Lion Corporation) Carbon for color, carbon for color (ink) subjected to oxidation treatment, and conductive carbon such as pyrolytic carbon can be used. Also, graphite such as natural graphite and artificial graphite can be used. Also, metal oxides such as TiO ₂ , SnO ₂ , ZnO, solid solutions of SnO ₂ and Sb ₂ O ₃ , composite oxides such as solid solutions of ZnO and Al ₂ O ₃ , metal powders such as Cu and Ag, etc. Various known materials can be used. You may use them individually or in mixture of multiple types. Further, a conductive polymer, an ionic conductive agent, or the like may be used in combination with the conductive filler.

  Among them, carbon black is preferable from the viewpoint of conductivity, and “Ketjen Black” (trade name, manufactured by Lion Corporation), which can give sufficient conductivity even when added in a small amount, is more preferable.

  The average particle size of the carbon black is not particularly limited. However, 30 nm or more and 60 nm or less are preferable. If it is smaller than 30 nm, it may be difficult to uniformly disperse in the conductive adhesive layer. Moreover, when using general carbon black, such as furnace black, when an average particle diameter exceeds 60 nm, it may become difficult to provide electroconductivity to the said conductive adhesive layer.

[Binder resin]
Examples of the binder resin include phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, butadiene resin, acrylonitrile resin, and styrene 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.

  As the thermosetting resin composition, a known thermosetting resin composition can be used. From the viewpoint of curability and adhesiveness, it is preferably a thermosetting resin composition containing at least a phenolic resin. .

  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.

  Although content of the phenol-type resin in the said thermosetting resin composition is not specifically limited, 96 mass% or more and 99 mass% or less are preferable.

  In addition to the conductive filler and the binder resin, the conductive adhesive layer may include an acid acceptor.

  The thickness of the conductive adhesive layer is preferably 5 μm or more and 10 μm or less. It is preferable that the thickness of the conductive adhesive layer is 5 μm or more because a sufficient barrier effect is produced. Moreover, when it is 10 micrometers or less, since an adhesive agent may not adhere to the inside of the electroconductive shaft guide in an extruder crosshead die, it is preferable.

  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 diluted to a predetermined concentration and applied as long as it has sufficient adhesive force required as a member used in the manufacturing process and in the image forming 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.

  However, when bonding with the conductive shaft body using the conductive adhesive layer in the present invention, it can have a function of protecting the conductive shaft body from chlorine, and poor adhesion even in an environment such as high temperature and high humidity It is possible to prevent corrosion of the conductive shaft body.

  The thickness of the conductive rubber elastic layer is preferably 1.0 mm or greater and 3.0 mm or less. It is preferable that the thickness of the conductive rubber elastic layer is 1.0 mm or more because it has sufficient elasticity. Moreover, when it is 3.0 mm or less, since material cost can be suppressed, it is preferable.

  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. It is more effective to pass through a crosshead die and coat the uncured rubber composition on the outer periphery of the conductive shaft body having the conductive adhesive layer, and then to manufacture through a vulcanization step.

  The conductive adhesive layer is excellent in conductivity, and also has a high ratio of binder resin and excellent adhesiveness. Therefore, 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 strength. When the ratio of the conductive filler contained in the conductive adhesive layer is greater than 8.15% by volume, the conductive adhesive layer applied to the conductive shaft body is somewhat thick in order to obtain a sufficient adhesive force. There is a need to. 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.

  In order to prevent this, if the inner diameter of the conductive shaft guide is increased, 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, if the ratio of the conductive filler contained in the conductive adhesive layer is 0.50% by volume or more and 8.15% by volume or less, the conductivity is excellent and the binder is used. Adhesiveness is also excellent due to the large proportion of resin. 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.

  The thickness of the surface layer is preferably 5 μm or more and 10 μm or less. A thickness of the surface layer of 5 μm or more is preferable because sufficient functionality of the surface layer is generated. Moreover, since it is easy to form a uniform surface layer when it is 10 micrometers or less, it is preferable.

  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) was prepared in which 10 parts by mass of Ketjen Black (trade name: “Ketjen Black EC-600JD”, manufactured by Lion Corporation) was preliminarily dispersed in 90 parts by mass of methyl isobutyl ketone. 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.) Manufactured, non-volatile content 20%) 100 parts by mass were mixed. As a result, a conductive adhesive having a ketjen black ratio of 0.5% by volume after application and drying of the adhesive was produced.

  Using a roll coater on a conductive shaft body in which the conductive adhesive is subjected to KN plating (film thickness 3 to 5 μm) on a SUM (sulfur composite free-cutting steel) having an outer diameter of φ6 mm preheated to 80 ° C., The film was applied so as to have a film thickness of 5 to 10 μm, and then 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 mass Ion conductive material (trade name: “LV-70”, manufactured by Asahi Denka Kogyo Co., Ltd.) 2 parts by mass 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) Product name: “Noxeller TS”, manufactured by Ouchi Shinko Chemical Co., Ltd.) 1 part by mass Sulfur (trade name: “Salfax PMC”, manufactured by Tsurumi Chemical Co., Ltd.) 0.8 parts by mass.

  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. The unvulcanized rubber composition was coated on the circumference. 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 grinding wheel “GC80” (trade name, manufactured by Tsugami Co., Ltd.). A conductive roller was fabricated by grinding so that the outer diameter was 12 mm at 0.3 m / min.

(Example 2)
Conductive adhesion 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, nonvolatile content 20%). A conductive adhesive having a ketjen black content of 2.70% by volume after coating and drying the agent was used. Otherwise, molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Example 3)
Conductive adhesion obtained by mixing 30 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, nonvolatile content 20%). A conductive adhesive having a ketjen black content of 8.15% by volume after coating and drying of the agent was used. Otherwise, molding was performed in the same manner as in Example 1 to produce a conductive roller.

Example 4
A dispersion (B) was prepared by preliminarily dispersing 10 parts by mass of furnace black (trade name: “Asahi # 70”, manufactured by Asahi Carbon Co., Ltd.) in 90 parts by mass of methyl isobutyl ketone. Conductive adhesion obtained by mixing 10 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, nonvolatile content 20%). A conductive adhesive having a furnace black content of 2.70% by volume after coating and drying of the agent was prepared and used. Otherwise, molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 1)
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, nonvolatile content 20%). A conductive adhesive having a ketjen black content of 0.27% by volume after applying and drying the conductive adhesive was used. Otherwise, molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 2)
Conductive adhesion obtained by mixing 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, nonvolatile content 20%). A conductive adhesive having a ketjen black content of 10.81% by volume after coating and drying of the agent was used. Otherwise, molding was performed in the same manner as in Example 1 to produce a conductive roller.

(Comparative Example 3)
Conductive adhesion obtained by mixing 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, nonvolatile content 20%). A conductive adhesive having a ketjen black content of 10.81% by volume after coating and drying 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, 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., 95%) for one month, 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]
A surface layer as shown below was applied to the conductive rollers obtained in the 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. Next, 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 paint was applied on the outer periphery of the conductive roller obtained in Examples and Comparative Examples so as to have a film thickness of 3 to 10 μm.

  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. Ten images were printed in solid white from the initial stage, and 10 images were evaluated. Image evaluation was performed as follows.

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

  From the results of Examples 1 to 4, in the conductive roller 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. Images 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.

  On the other hand, in Comparative Example 1, since the ratio of ketjen black contained in the conductive adhesive layer is small, current value max-min and current value circumferential unevenness are slightly larger than those in Examples 1 to 4, and image evaluation Slight image density unevenness was observed.

  Further, in Comparative Example 2, the current value max-min and the current value circumferential unevenness are small, but a sufficient adhesive force cannot be obtained because the ratio of the binder resin contained in the conductive adhesive layer is small. Density unevenness occurred. Furthermore, after long-term storage, peeling of the conductive rubber elastic layer and the conductive shaft body was confirmed with 21 conductive rollers.

  In Comparative Example 3, since the adhesive coating is thick, the adhesive adheres to the inside of the conductive shaft guide in the extruder crosshead die, and the conductive shaft is clogged in the conductive shaft guide. Therefore, the 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 (7)

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 adhesive layer includes at least a conductive filler and a binder resin,
The conductive adhesive layer contains the conductive filler in an amount of 0.50% by volume to 8.15% by volume.   The conductive roller according to claim 1, wherein the conductive filler is carbon black.   The conductive roller according to claim 1 or 2, wherein the binder resin is a thermosetting resin composition containing at least a phenolic resin.   The conductive roller according to claim 1, wherein the conductive rubber elastic layer includes epichlorohydrin rubber.   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 4, 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,
5. 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 6.

Images