JP2007193001A - Manufacturing method for conductive roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide conductive roller; without any extruding of adhesive from an end part of a conductive elastic layer, without any remaining rubber on the end part, without any peeling of the adhesive even when left standing under high temperature and high humidity, and therefore with no occurrence of an abnormal image due to an adhesion failure. <P>SOLUTION: The manufacturing method for the conductive roller on which the adhesive is coated on a conductive substrate and more than one resistance layer is further coated on it is provided with a distribution of adhesive thickness in an axial direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a conductive roller such as a charging roller, a developing roller, or a transfer roller used in an image forming apparatus such as a copying machine or a laser printer.

  In electrophotographic apparatuses typified by copying machines and printers, generally, a charging roller that uniformly charges a drum-shaped photoconductor, a developing roller that conveys toner to the photoconductor, and a toner image formed on the surface of the photoconductor are printed on paper. For example, a conductive roller such as a transfer roller for transferring to the surface of a transfer material is used.

These conductive rollers have a volume resistance value controlled within a range of 10 ⁵ to 10 ¹⁴ Ωcm, and a material of a so-called semiconductive region is used. In the prior art, the conductive roller is manufactured by kneading a mixture of a vulcanizing agent, a plasticizer, a conductive filler and the like into an insulating solid rubber to obtain a conductive rubber composition, which is formed into a tube shape by an extruder. After extrusion, vulcanize to form a rubber tube. Next, a conductive base material coated with an adhesive is inserted (press-fitted) into the hole portion of the obtained rubber tube, and a conductive roller material is molded through an adhesion process such as heating.

  As shown in FIG. 1, the conductive roller material includes a conductive substrate 1a and a rubber tube layer 2 on the outer peripheral surface thereof with an adhesive 2c interposed therebetween. The surface of the conductive roller material is polished by a polishing machine, and the end portion of the rubber tube is cut (cut off) to remove the end rubber 2d to obtain an elastic resistance layer. Further, when a conductive coating layer is provided on the surface, the coating layer is provided by coating or the like.

  Along with the recent high performance of electrophotographic apparatuses, the characteristics of the conductive roller are also required to suppress the unevenness of electric resistance more than before. Therefore, the production of conductive rollers using an ion conductive rubber composition in which the rubber itself has polarity and exhibits conductivity without adding a conductive filler is increasing.

  As such an ion conductive rubber composition, epichlorohydrin rubber (CO, ECO, GECO), acrylonitrile-butadiene rubber (NBR), acrylic rubber (ACM) and chloroprene rubber (CR) are generally used. Etc.

  However, such a rubber composition having ionic conductivity has a high hygroscopic property, and thus has a characteristic that volume expansion is relatively large in a high temperature and high humidity state. Therefore, when a conductive roller made of ionic conductive rubber is left for a long time in a high temperature and high humidity state, the elastic elastic layer made of ionic conductive rubber adheres between the elastic resistance layer and the conductive substrate due to volume expansion. There was a case where peeling occurred. There is a problem in that the electrical resistance becomes uneven at the place where the adhesion peeling occurs, causing an abnormal image.

  Therefore, as a means to suppress poor adhesion, a method of increasing the adhesive thickness by increasing the thickness of the adhesive, or a rubber tube molded with a smaller inner diameter than the conventional outer diameter of the conductive base to thicken the conductive base. A method of improving the tightening force of the rubber tube by entering is taken.

  However, in these methods, although the adhesive is not applied to the surface of the conductive substrate corresponding to the end rubber 2d, the adhesive enters and the end rubber 2d cannot be easily removed. Even if it is removed, there is a problem that dirt due to the adhesive remains on the surface of the conductive substrate. For these reasons, there has been a problem that when incorporated in an electrophotographic apparatus, the conductive roller does not rotate normally and an abnormal image is generated.

  As a result of examining the reason why the adhesive enters the end rubber region, when the rubber tube is inserted into the conductive substrate, the inner diameter of the rubber tube is equal to or smaller than the outer diameter of the conductive substrate. Therefore, it has been found that the cause is that the adhesive is squeezed out toward the end due to the tightening force of the rubber tube. It has been found that this particularly occurs when the adhesive is applied thick and the inner diameter of the rubber tube is reduced, or when the adhesive is not completely dried. Further, it was found that the inner surface of the rubber tube was rubbed with the adhesive layer by the thick insertion step and moved in the thick insertion direction, so that it became thicker on the downstream side in the thick insertion direction and the adhesive was easily squeezed out.

  In order to easily perform the process of removing the end rubber 2d of the rubber tube, as a conventional technique, a method has been disclosed in which a predetermined range from both end surfaces of the rubber layer 2a is set as an unbonded region in which no adhesive is previously applied (for example, a patent). Reference 1).

  In such a conventional technique, when the adhesive is applied thickly and the inner diameter of the rubber tube is reduced, the adhesive is easily squeezed out by the thickening process. It is necessary to set. However, the sticking out of the adhesive does not occur uniformly in the circumferential direction, and since there is no adhesive, a portion that becomes an unbonded region remains inside, and there is a problem that the rubber layer is lifted.

  On the other hand, in order to generate a resistance distribution in the axial direction of the conductive roller, a method of providing a high and low distribution in the thickness of the semiconductive adhesive layer provided between the conductive foam and the conductive tube is disclosed. (For example, refer to Patent Document 2).

However, this method forms an adhesive layer as a resistance layer for giving a resistance distribution in the axial direction, and forms a high-low distribution in the thickness thereof. No mention is made of a method of manufacturing a conductive roller that does not cause poor adhesion even when left in a state for a long time, does not cause image defects, and is easy to cut off and remove the end rubber in the manufacturing process. Not.
JP 09-029843 A JP 2004-301929 A

  The present invention has been made in view of such circumstances, and in a conductive roller having a conductive elastic layer on an outer periphery of a conductive substrate via an adhesive layer, the conductive substrate and the conductive elastic layer are Good adhesion, no adhesion failure even if left for a long time in high temperature and high humidity condition, no image defect caused by it, and easy to cut off and remove the end rubber in the manufacturing process The present invention provides a method for producing a conductive roller in which the adhesive does not protrude from the end face of the conductive elastic layer.

  According to a first aspect of the present invention, there is provided a method for manufacturing a conductive roller, wherein the conductive substrate is coated with an adhesive, and the adhesive is coated with one or more resistive layers. And having a distribution in the longitudinal direction.

  The conductive roller manufacturing method according to the second invention is characterized in that the thickness distribution in the longitudinal direction of the adhesive is such that the edge of the adhesive is covered thinner than the center.

  In the method for manufacturing a conductive roller according to the third invention, the average thickness of the adhesive in the region 1/8 of the entire coating region from the end portion is different at both end portions, and the end portion of the conductive substrate on the side having a smaller average thickness is provided. The conductive substrate is disposed so as to be a rear end when press-fitted into a rubber tube as a conductive elastic layer material.

  In the method for manufacturing a conductive roller according to the fourth invention, the average thickness of the adhesive in the region 1/8 of the entire coating region from the end is set to 3 μm or more and 15 μm or less, and the average thickness of the central portion excluding them is set. It is characterized by being 50 μm or less.

  As described above, according to the present invention, there is no protrusion of the adhesive, so that the end rubber can be easily removed, the adhesion between the conductive substrate and the conductive elastic layer is good, and the temperature is high. Even if left in a wet state, no adhesion failure occurs, and therefore a conductive roller can be produced in which no abnormal image is generated due to conductivity failure.

  An embodiment of the method for producing a conductive roller of the present invention will be described in detail. Embodiments in which the present invention is applied as a method for manufacturing a charging roller will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of a conductive roller made according to the present invention, FIG. 2 is a cross-sectional view showing an embodiment in which the conductive roller made according to the present invention is a charging roller, and FIG. 3 is made according to the present invention. FIG. 4 is a cross-sectional view showing an example of a charging device in which a charging roller is applied to the conductive roller, and FIG. 4 is a cross-sectional view showing an example in which the charging roller is applied to an image forming apparatus.

  As shown in FIG. 2, the charging roller of the present invention comprises a conductive substrate 1a, an adhesive layer 2c coated on the outer periphery thereof, a conductive elastic layer 2a, and a surface layer 2b. Moreover, it is good also as a structure which provided the 1 or more resistance layer between the electroconductive elastic layer and the surface layer.

  In the present invention, the adhesive layer 2c must have an adhesive thickness distribution in the axial direction of the conductive substrate. This not only strengthens the adhesion with the inner surface of the tube by increasing the thickness of the adhesive, but also provides a thick adhesive even when the inner diameter of the rubber tube is reduced by providing a thin region of the adhesive. Since the adhesive squeezed out from the region does not squeeze out beyond the thin portion, the adhesive does not stick out to the inner surface of the end rubber.

  From the viewpoint of adhesive strength, the adhesive is preferably applied to the end surface of the conductive elastic layer. In the present invention, a conductive roller was created by providing a distribution in the thickness of the adhesive so that the adhesive does not protrude even when the adhesive is applied to the end surface of the conductive elastic layer.

  The thickness of the adhesive is preferably 50 μm or less. Even when the adhesive thickness is 50 μm or more, there is almost no improvement in adhesive strength, and when an adhesive diluted with a solvent is used, the adhesive layer is applied to a thickness of 50 μm or more. However, since the drying inside is slow, the adhesive is likely to move during the press-fitting process.

  Since the thick insertion process is mechanically performed by an automatic press-fitting machine or the like, the inner diameter of the rubber tube is preferably 60% or more with respect to the outer diameter of the conductive substrate, and 98% or less for tightening the conductive substrate. When the clamping force is small, such as when the layer is made of an ion conductive rubber or a foam, it is preferable that the layer is manufactured at 80% or less.

  In order to obtain a tightening force of the rubber tube against the conductive substrate, the 10% modulus of the rubber tube material is preferably 0.01 MPa or more. In order to perform the press-fitting process mechanically, the 10% modulus is preferably 1 MPa or less.

  Even when the inner diameter of the rubber tube is small relative to the outer diameter of the conductive substrate or when the 10% modulus is high, in order to suppress the protrusion of the adhesive, the thickness should be reduced in the region where the adhesive is thin. It is preferable to make it 15 μm or less. On the other hand, in order to prevent the rubber layer from floating even when the tightening force by the rubber tube is weak and the movement of the adhesive is small, or even in the area where the adhesive does not move because the adhesive is not even in the circumferential direction. In addition, in the region where the adhesive is thin, the thickness is preferably 3 μm or more.

  Furthermore, it is preferable that the thickness of the edge part of an adhesive agent is formed thinner than the area | region of another center part. Thereby, even if the fastening force of the rubber tube is large as described above, the protrusion of the adhesive can be suppressed. The size of the thin region of the adhesive can be set as appropriate depending on the extent to which the adhesive is squeezed out from the thick region of the adhesive, but if the adhesive is thick in the region of about 50 μm, the adhesive application region from the end It can be seen that the region where the length is 1/8 of the thickness of the adhesive should be a thin region. By providing an adhesive layer with an average thickness of 15 μm or less, the adhesive does not stick out to the end rubber. I understood that.

  The thickness of the adhesive may be changed continuously or stepwise, but it is preferable to change uniformly in the circumferential direction. As processing means for giving the adhesive thickness distribution in this way, for example, a method of rotating the conductive substrate chucked at both ends in the circumferential direction and adjusting the coating speed by spray coating to have a film thickness distribution, , A method of adjusting the roll shape on the roll coater to give a film thickness distribution, a method of adjusting the coating amount of the adhesive by brush coating to give a film thickness distribution, a sponge etc. while changing the dropping speed of the adhesive A known method such as a method of moving the coating jig on the surface of the conductive substrate may be selected.

  As the material of the adhesive, a liquid adhesive obtained by diluting the adhesive in an appropriate organic solvent to give a thickness distribution is preferable, and either an insulating adhesive or a conductive adhesive can be used. The conductive adhesive is preferable because it does not cause uneven electrical resistance due to the thickness distribution. Also, one-component desiccant adhesive, chemical reaction type adhesive, hot melt type adhesive, adhesive type adhesive may be used, urea resin type, melamine resin type, phenol resin type, epoxy resin type, vinyl acetate resin type, Synthetic resin adhesives such as cyanoacrylate, polyurethane, α-olefin-maleic anhydride resin, aqueous polymer-isocyanate, reactive acrylic resin, modified acrylic resin, and other resins, vinyl acetate resin , Vinyl acetate copolymer resin-based, EVA resin-based, acrylic resin-based, other resin-based emulsion-based adhesives, chloroprene-based, other synthetic rubber-based synthetic rubber adhesives and hot-melt adhesives, What is necessary is just to use what disperse | distributed carbon black, a metal powder, a metal oxide etc. as an electroconductive filler. In particular, when ion conductive rubber such as hydrin rubber is used as the conductive elastic layer, phenolic resin, epoxy resin or a mixture thereof, and carbon black as a conductive agent are mixed with elastic rubber such as NBR or urethane rubber. The conductive adhesive thus obtained is preferable from the viewpoint of rust prevention of the conductive substrate while having good followability to the conductive elastic layer and excellent adhesion.

  The conductive substrate used in the present invention can be any material as long as the conductivity and required shape accuracy are satisfied. For example, a round bar made of a metal material such as iron, copper, stainless steel, aluminum and nickel. Can be used. Furthermore, for the purpose of imparting rust prevention and scratch resistance to these metal surfaces, it is preferable to perform plating so as not to impair the conductivity. There are two general plating methods: electrolytic plating and electroless plating. The latter is superior in uniformity of the plating film thickness, so high accuracy is obtained and defects such as pinholes are obtained. Therefore, it is preferably selected from the viewpoint of excellent corrosion resistance. Further, among electroless plating, electroless nickel plating is more preferably used from the viewpoint of the stability of the plating solution and cost. Moreover, even if it is hollow or solid, it can be used without any problem. From the viewpoint of strength and cost, a solid metal rod made of iron and having a diameter of 4 mm to 10 mm is preferably plated with nickel.

  The elastic resistance layer 2a is manufactured by blending a rubber material such as solid rubber and liquid rubber with a vulcanizing agent, plasticizer, conductive agent and other fillers, and blending with a kneader, Banbury mixer, open roll, dynamic mixer, etc. A rubber composition mixed with an agent is prepared. Next, injection molding or transfer molding in which the rubber composition is injected into the mold, and extrusion molding to extrude into a tube shape using an extruder and then vulcanize with a vulcanizing can, hot air drying oven, etc. A hollow rubber tube is molded by a known method.

  Next, a rubber tube is press-fitted into the conductive substrate coated with an adhesive so as to have the predetermined thickness distribution described above.

  Here, the direction of press-fitting of the rubber tube is such that the side where the average thickness of the adhesive is thin in the region of 1/8 length from the end of the adhesive application region is the rear end with respect to the rubber tube. It is preferable to place and press fit. As a result, even when the adhesive is rubbed by the inner surface of the rubber tube and moved easily, such as insufficient drying of the adhesive, the adhesive does not stick out to the inner surface of the end rubber. In this case, the average thickness of the adhesive in the length of 1/8 of the adhesive application area at both ends can be set as appropriate depending on the degree of movement of the adhesive in the press-fitting, but the inner diameter and modulus of the rubber tube described above In this range, the average thickness of the adhesive on the rear end side in the press-fitting direction is preferably 10 μm or less.

  Further, a vulcanizing agent is appropriately blended in the conductive elastic layer. As vulcanizing agents, depending on the type of rubber used, sulfur vulcanizing agents, organic peroxides, quinoid vulcanizing agents, resin crosslinking agents, metal oxide crosslinking agents, amine crosslinking agents, triazine crosslinking agents, maleimides A known vulcanizing agent such as a system cross-linking agent can be used as appropriate, and in addition, a vulcanization accelerator, an anti-aging agent, a plasticizer, and the like may be added.

  The elastic resistance layer 2a has appropriate conductivity and elasticity to make the contact with the photosensitive drum, which is a member to be charged, uniform, and has a shape in which the central portion is thickest by polishing and becomes thinner toward both ends. It is preferable to form a so-called crown shape. In the electrophotographic apparatus shown in FIG. 4, the charging roller 4 applies a predetermined pressing force to both ends of the conductive substrate 1a and is in contact with the electrophotographic photosensitive drum 12, so that the pressing force at the center is small. Since the both ends are larger, there is no problem if the straightness of the charging roller 2 is sufficient, but if it is not sufficient, density unevenness may occur in the images corresponding to the center and both ends. . The crown shape is formed to prevent this. The thickness of the elastic resistance layer 2a is not particularly limited, but is preferably 1 mm or more and 10 mm or less in order to maintain elasticity and make it contact with the charged body uniformly.

  Examples of the rubber material used for the conductive elastic layer 2a include EPDM, polybutadiene, natural rubber, polyisoprene, SBR (styrene butadiene rubber), CR (chloroprene rubber), NBR (nitrile butadiene rubber), silicone rubber, and urethane. Rubber, epichlorohydrin rubber and the like can be used. In particular, in the charging roller for charging the charged body, in order to achieve charging uniformity, it is particularly preferable to use a medium resistance polar rubber such as epichlorohydrin rubber, NBR, CR and urethane rubber by an ion conduction mechanism. .

  In the case of adding a conductive material in the present invention, a known conductive material can be used, acetylene black, conductive carbon black or graphite of ketjen black, metal oxide such as metal powder, titanium oxide, tin oxide, zinc oxide, Alternatively, tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, iron, copper, chromium, cobalt, lead, platinum, rhodium are electrolyzed, spray-coated, mixed on the surface of suitable particles It may be attached by shaking. In addition, quaternary alkylammonium salts such as tetraethylammonium and tetrabutylammonium sulfonate, polyethylene oxide modified products thereof, metal salts such as lithium perchlorate and sodium bromate, or ionic properties such as ester plasticizers and surfactants A conductive agent may be used. In the present invention, an ion conductive conductive elastic layer is used, and an epichlorohydrin rubber is used by mixing a quaternary ammonium salt as an ionic conductive agent, and the addition amount of the quaternary ammonium salt is adjusted within the above resistance range.

  The conductive elastic layer is solid in the present invention, but may be a foam. When a foam is produced by using a foaming agent, the foaming agent may be A. D. C. A. (Azodicarbonamide), D.I. P. T. (Di-nitrosopentamethylenetetramine) system, O.D. B. S. H. (4.4'-oxybis-benzenesulfonyl-hydrazide) system, T.P. S. H. (P-trienesulfonyl hydrazide) system, A.I. I. B. N. (Azobisisobutyronitrile) type and the like can be used.

  The binder resin for the surface layer 2b is preferably a crosslinkable resin from the viewpoint of preventing the elastic resistance layer from seeping out and preventing adhesion of toner and the like. Fluorine resin, polyamide resin, silicone resin, RB (butadiene resin), SBS ( Polystyrene resins such as styrene / butadiene / styrene elastomer), polyolefin resins, polyester resins, polyurethane resins, PVC (polyvinyl chloride), acrylic resins, styrene / vinyl acetate copolymers, butadiene / acrylonitrile copolymers, etc. These polymer materials can be used. In order to form the resistance layer, one kind of these materials may be used or two or more kinds may be used in combination. In addition, when a crosslinking agent is blended in the surface layer, conventionally used crosslinking agents such as isocyanate crosslinking agents, melamine crosslinking agents, and amine crosslinking agents can be used as the crosslinking agent. In the present invention, an acrylic resin is used from the viewpoint of moldability and flexibility of the resistance layer, and an isocyanate crosslinking agent is used as a curing agent.

  In addition, a known matting agent may be used to adjust the surface roughness of the charging roller. Among them, mixing resin particles such as urethane resin, acrylic resin, and silicone resin is preferable in terms of dispersibility and flexibility. preferable. From the viewpoint of preventing toner contamination, the 10-point average surface roughness of the charging roller surface is preferably 2 μm or more and 15 μm or less.

  The method for forming the surface layer is not particularly limited, but the resin composition constituting the surface layer is applied to a predetermined thickness from above the conductive elastic layer using a method such as spray coating, dip coating, or roll coating. By drying and curing at a predetermined temperature, a surface layer can be formed on the conductive elastic layer, and the dip coating is preferable because the manufacturing apparatus is simple and the usage rate of the material is high. .

  The conductive material added to the surface layer preferably has electronic conductivity due to a small variation in resistance value due to changes in temperature and humidity. Examples of the conductive agent for developing electron conductivity include metals or alloys such as carbon black, graphite, aluminum, nickel, and copper alloys, tin oxide, zinc oxide, potassium titanate, tin oxide-indium oxide, and tin oxide. -Metal oxides, such as an antimony oxide complex oxide, etc. are mentioned, A metal oxide is preferable at a dispersible point.

  The film thickness of the surface layer 2b is preferably 3 to 30 μm. If the thickness is less than 3 μm, it is difficult to adjust the resistance of the surface layer. If the thickness is more than 30 μm, a large amount of conductive particles are required to obtain a desired resistance as a charging roller, which is not preferable because it easily aggregates.

The volume resistance value of the charging roller 4 is preferably 1 × 10 ⁴ Ω · cm or more from the viewpoint of preventing an excessive current to the member to be charged, and 1 × 10 ¹³ Ω · cm for charging the surface of the member to be charged. cm or less is preferable.

  In FIG. 3, a charging device 1 is composed of a charging roller 4 and a power source 3, and a photosensitive drum 12, which is a drum-shaped electrophotographic photosensitive member, is OPC, amorphous on a grounded drum base that can rotate in the R direction. It has a structure in which a photoconductor such as silicon, selenium, or zinc oxide is covered.

  In the electrophotographic apparatus 150 shown in FIG. 4, the charging roller 4 is driven to rotate at both ends of the conductive substrate 1 a by the unillustrated pressing means as the photosensitive drum 12 is driven to rotate. A predetermined direct current (DC) bias is applied to the conductive substrate 1a by the power source 3, whereby the peripheral surface of the photosensitive drum 12 is contact-charged to a predetermined potential. The photosensitive drum 12 that has been uniformly charged by the charging roller 2 is then subjected to exposure of target image information (laser beam scanning exposure, slit exposure of a document image, etc.) by the exposure means 20, so that the target image is formed on the peripheral surface thereof. An electrostatic latent image for information is formed.

  The latent image is then successively visualized as a toner image by the developing means 24. The toner image is then transferred from the sheet feeding means (not shown) by the transfer means 25 in synchronization with the rotation of the photosensitive drum 12 and conveyed to the transfer section between the photosensitive drum 12 and the transfer means 25 at an appropriate timing. The images are sequentially transferred to the 26th surface. The transfer means 25 of this example is a roller-shaped transfer roller, and the toner image on the photoconductor 12 is transferred to the front surface side of the transfer material 26 by charging the reverse polarity of the toner from the back of the transfer material 26.

  The transfer material 26 that has received the transfer of the toner image is separated from the photosensitive drum 12, conveyed to an image fixing unit (not shown), subjected to image fixing, and output as an image formed product. Alternatively, in the case of forming an image on the back side, it is conveyed to a re-conveying means to the transfer unit.

  After the image transfer, the photosensitive drum 12 is subjected to the removal of adhering contaminants such as transfer residual toner by the cleaning means 27 to be cleaned and repeatedly used for image formation.

  A DC voltage of -1200 V was applied to the charging roller 4 from the power source 3 to charge the surface potential of the OPC photosensitive drum to -500 V, and the peripheral speed of the OPC photosensitive drum was set to 150 mm / sec.

  The toner was externally added with silica fine particles in which a random copolymer of styrene and butyl acrylate containing a charge control agent, a pigment and the like centered on wax was polymerized, and a polyester thin layer was polymerized on the surface. This toner is a polymerized toner having a glass transition temperature of 63 ° C. and a volume average particle diameter of 6 μm.

  The charging roller used in this example was manufactured by the following method.

  Epichlorohydrin rubber (trade name: Epichromer (Epichromer is a registered trademark) CG102, manufactured by Daiso Corporation) 100 parts by weight, calcium carbonate as filler 30 parts by weight, carbon black (trade name: Seast (Seast is a registered trademark) 3 parts by mass, 5 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 5 parts by mass of DOP as a plasticizer, 4 parts by weight of a quaternary ammonium salt, 2-mercaptobenzimidazole as an antioxidant The material compound was adjusted by kneading for 10 minutes in a closed mixer whose mass part was adjusted to 60 ° C. To this compound, 1 part by mass of DM as a vulcanization accelerator, 1 part by mass of TS as a vulcanization accelerator, and 1 part by mass of sulfur as a vulcanization agent were added and kneaded with an open roll for 15 minutes.

  Using the rubber extruder, a rubber tube material is prepared from the obtained compound, and then heated and vulcanized at 160 ° C. for 30 minutes using a steam vulcanizer, the inner diameter is 4.5 mm, the outer diameter is 12.2 mm, A rubber tube having a length of 240 mm was prepared.

  3% carbon black (MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) is mixed with 3 rolls with respect to the solid content of thermosetting adhesive (trade name: METALOC U-20), and the conductive adhesive has a volume resistance of 10 Ωcm. An agent was created. Adhesive agent is applied to the sponge pressed against the peripheral surface of the conductive substrate while chucking and rotating 3 mm at both ends of a cylindrical conductive substrate (steel, surface is nickel-plated) having a diameter of 6 mm and a length of 250 mm. While dripping, it was moved in the axial direction, coated with an adhesive, and dried at room temperature. The thickness of the adhesive is adjusted by varying the amount of dripping. The adhesive is not applied in the range of 10 mm from both ends of the conductive substrate, and the thickness is in the range of 10 mm to 37.5 mm from the one end (A end). Was 10 μm, the thickness was 15 μm in the range from 10 mm to 37.5 mm from the other end (B end), and the adhesive was applied so that the thickness was 50 μm at the center from both ends 37.5 mm.

  The thickness of the adhesive is determined by measuring the shape of the conductive substrate before applying the adhesive with a laser length measuring machine in advance, measuring it again after applying the adhesive, and calculating the difference in 360 locations in the circumferential direction. Obtained by arithmetic mean. Moreover, the average thickness in a certain area | region was calculated by the arithmetic average at the time of measuring the area | region at intervals of 0.5 mm.

  Push the B end of the conductive substrate 5 mm into the inner end of the resulting rubber tube, and send pressurized air from the opposite end of the rubber tube to the center of the conductive substrate and the center of the rubber tube. Was press-fitted so that they almost coincided. Next, the elastic resistance layer material was obtained by heating and bonding at 160 ° C. for 30 minutes in an electric oven. Cut off at the position of 10 mm from both ends of the rubber part of the obtained elastic resistance layer material, and the end rubber was removed.

  Further, the surface of the elastic resistance layer material was polished with a rotating grindstone to obtain a crown-shaped elastic resistance layer having an end diameter of 12.00 mm and a central diameter of 12.10 mm.

  As a coating material for the surface layer, 100 parts by mass of polyester polyol (Nipporan (Nipporan is a registered trademark) 131 Nippon Polyurethane Industry Co., Ltd.), conductive acetylene black (# 4500 manufactured by Tokai Carbon Co., Ltd.) 15 as a conductive material 200 parts by mass of ethyl acetate as a part by mass and 50 parts by mass of the non-conductive particles described above were added, and dispersion treatment was performed for 10 hours using a paint shaker. Next, 90 parts by mass of an isocyanate resin (coronate (coronate is a registered trademark) L Nippon Polyurethane Industry Co., Ltd.) having a solid content of 75% was added to obtain a surface layer composition having a viscosity of 10 mPa · s.

A coating material for the surface layer was applied to the elastic body by dipping, and the crosslinking reaction was performed by heating at 150 ° C. for 1 hour, whereby the charging roller 1 was prepared. At this time, the pulling speed (moving speed of the elastic body with respect to the resistance layer composition) was controlled to 20 mm / s at the upper end, and then linearly decelerated to 2 mm / s at the lower end. The charging roller 1 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  As for the resistance value of the charging roller, the foam was brought into contact with the cylindrical metal drum and rotated, and a DC voltage of 100 V was applied between the conductive substrate and the metal drum to connect the metal drum in series. It was determined by measuring the voltage applied to the resistor.

  As for the surface roughness of the charging roller 1, a surface roughness measuring device (trade name: Surfcoder SE-33-H, manufactured by Kosaka Laboratory) was used, and the conditions were a cutoff of 0.8 mm and a feed rate of 0.2 mm / s. T An average value was obtained by arithmetic average at a position of 15 mm from each end of the charging roller in the axial direction and at three positions in the center.

  The thickness of the surface layer was observed with an electron microscope at five locations in the axial direction, and the average value was obtained by arithmetic average. The charging roller 1 had a surface layer thickness of 10 μm.

  Table 1 shows the occurrence of irregularities on the charging roller by visual inspection for the presence or absence of floating between the conductive substrate and the elastic resistance layer after leaving the charging roller 1 in an atmosphere of 50 ° C. and 98% for 10 days. The result observed about is shown. Further, the results of checking whether or not an abnormal image is generated after being left in an atmosphere of 50 ° C. and 98% for 10 days and then left at 25 ° C. and 50% for 3 days are incorporated into the electrophotographic apparatus 1 are shown.

  Moreover, the result observed about the protrusion of an adhesive agent from an electroconductive elastic layer end surface is shown.

  In Table 1, ◎ indicates that there is no float, ◯ indicates that there is very slight occurrence, but ○ indicates that there is no image failure, but there is slight lift, and slight charging failure is observed by image evaluation. The level at which there was no problem in actual use was indicated by Δ, and the level at which floating was observed, and the case where defective charging was observed at a bad level from the image was indicated by ×. In addition, after the end rubber removal process, visually observe the end surface of the conductive elastic layer, ◎ if there is no adhesive sticking out, the sticking out is very slight, poor image due to rotation failure O, where there is no occurrence of color, slightly protruding, and streaks of the charging roller cycle due to rotation failure are slightly generated as image defects, but △, where there is no practical problem, erosion of adhesive It was indicated as “x”, which can be easily observed and the streaks of the charging roller cycle due to poor rotation are observed at a bad level.

  As shown in Table 1, the charging roller 1 was free from any floating due to poor adhesion, and the adhesive did not protrude at all.

Example 1 is the same as Example 1 except that the thickness of the adhesive in the region from 10 mm to 37.5 mm on the A end side is 3 μm, and the thickness of the adhesive in the region from 10 mm to 37.5 mm on the B end side is 15 μm. The charging roller 2 was prepared. The charging roller 2 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  The charging roller 2 was free from floating due to poor adhesion, no defective image, and no adhesive sticking out.

In Example 1, the thickness of the adhesive in the region of 10 mm to 37.5 mm on the A end side is 12 μm, the thickness of the adhesive in the region of 10 mm to 37.5 mm on the B end side is 20 μm, and the central portion from 37.5 μm on both ends Then, the charging roller 3 was prepared in the same manner as in Example 1 except that the thickness was 60 μm. The charging roller 3 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  The charging roller 3 was free from floating due to poor adhesion and no image failure. Further, the protrusion of the adhesive did not occur on the A end side and occurred very slightly on the B end side, but no image defect occurred.

In Example 1, the thickness of the adhesive in the region from 10 mm to 37.5 mm on the A end side is 1 μm, the thickness of the adhesive in the region from 10 mm to 37.5 mm on the B end side is 2 μm, and the central portion from both ends 37.5 μm Then, the charging roller 4 was prepared in the same manner as in Example 1 except that the thickness was 60 μm. The charging roller 4 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  The charging roller 4 did not protrude any adhesive. Further, although the float due to poor adhesion occurred very slightly at both ends, no image defect occurred.

In Example 1, the thickness of the adhesive in the region from 10 mm to 37.5 mm on the A end side is 1 μm, the thickness of the adhesive in the region from 10 mm to 37.5 mm on the B end side is 20 μm, and the central portion from both ends 37.5 μm Then, the charging roller 5 was prepared in the same manner as in Example 1 except that the thickness was 60 μm. The charging roller 5 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  On the charging roller 5, the protrusion of the adhesive was observed very slightly on the B end side, but no image defect occurred. Further, although the float due to poor adhesion occurred very slightly on the A end side, no image defect occurred.

In Example 1, the same procedure as in Example 1 was performed except that the thickness of the adhesive in the region from 10 mm to 37.5 mm at both ends was 25 μm, and the thickness from 37.5 μm to both ends was 60 μm. Created. The charging roller 6 had a resistance value of 6 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  In the charging roller 6, the adhesive protrusion is observed very slightly on the B end side and slightly on the A end side, and the charging roller cycle has a slight streak defect, but there is no practical problem. there were. Further, there was no floating due to poor adhesion, and there was no image defect.

(Comparative Example 1)
A charging roller 7 was prepared in the same manner as in Example 1 except that the adhesive was applied to the entire area excluding 10 mm from both ends with a thickness of 60 μm. The charging roller 7 had a resistance value of 5 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  The charging roller 7 did not float due to poor adhesion and did not cause image failure due to floating. However, when the adhesive protrudes, it can be easily observed at both ends. It was a practically problematic level.

(Comparative Example 2)
Example 1 except that the adhesive was not applied in the region from 10 mm to 37.5 mm on the A end side in Example 1, and the thickness of the adhesive was changed to 60 μm in the region from 37.5 μm on the A end side to 10 mm on the B end side. The charging roller 8 was prepared in the same manner as described above. The charging roller 8 had a resistance value of 8 × 10 ⁷ Ω, a surface layer thickness of 10 μm, and a ten-point average surface roughness of 2.5 μm.

  The charging roller 8 can be easily observed on the B-end side, and the streak of the charging roller cycle is a practically problematic level in image evaluation. Further, floating was observed on the A end side, and remarkable charging failure was also observed from the image evaluation.

Cross-sectional conceptual diagram of a charging roller applied to Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1 and 2 of the present invention Sectional drawing which shows an example of the charging roller of this invention Charging apparatus to which the charging roller of the present invention is applied Image forming apparatus to which charging roller of the present invention is applied

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact charging device 1a Conductive base | substrate 2a Conductive elastic layer 2b Surface layer 2c End rubber | gum 3 Power supply 4 Charging roller 12 Photoconductor 13 Nip part 150 Electrophotographic apparatus

Claims (4)

In a method for producing a conductive roller, in which a conductive substrate is coated with an adhesive, and one or more conductive elastic layers are coated on the adhesive,
A method for producing a conductive roller, wherein the thickness of the adhesive has a distribution in the longitudinal direction.   2. The method for producing a conductive roller according to claim 1, wherein the thickness of the adhesive in the longitudinal direction covers the end portion thinner than the central portion.   The average thickness from the end of the adhesive application area to 1/8 of the application area is different at both ends, and the end of the thin average thickness is placed on the conductive substrate coated with the adhesive. The method for manufacturing a conductive roller according to claim 1, wherein when press-fitting into the part, the rear end is arranged with respect to the direction of press-fitting into the conductive elastic layer.   The thickness of the adhesive is characterized in that the average thickness from the end part to 1/8 of the application area is 3 μm or more and 15 μm or less, and the thickness of the adhesive in the central part excluding them is 50 μm or less, The method for producing a conductive roller according to claim 1.

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