JP2006284835A - Conductive roller and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a conductive roller having no projecting flaw at the exposed part of a shaft core without exerting influence on an elastic layer or the like. <P>SOLUTION: The method of manufacturing the conductive roller having the shaft core made of metal and the elastic layer arranged on the outer periphery of the shaft core, and having the exposed parts of the shaft core where the shaft core is exposed at both ends in a longitudinal direction includes: a stage for providing the elastic layer on the outer peripheral surface of the shaft core other than the exposed part of the shaft core; and a stage for burnishing the exposed part of the shaft core. In the conductive roller having the shaft core made of metal and the elastic layer arranged on the outer periphery of the shaft core, and having the exposed parts of the shaft core where the shaft core is exposed at both ends in the longitudinal direction, the exposed part of the shaft core is burnished. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive roller used in an image forming apparatus or the like that employs an electrophotographic system such as a printer, a facsimile machine, and a copying machine, and a manufacturing method thereof.

  In recent years, OA equipment such as copying machines and printers has been improved in image quality, and accordingly, a developer having an elastic layer as a developer carrying roller in a developing process for visualizing an electrostatic latent image on a photoreceptor with toner. There has been proposed a contact development method in which development is performed by using a carrying roller and uniformly contacting a photoreceptor. In this contact development method, the developer carrying roller has an elastic layer made of an elastic material in order to secure a uniform pressure contact width to the photoconductor, and a voltage is applied to the toner image on the photoconductor. Therefore, uniform conductivity and leak resistance are required.

  Therefore, for example, an elastic layer in which an electronic conductive agent or an ionic conductive agent is dispersed and adjusted to a desired resistance value is formed on the shaft core, and wear resistance, toner chargeability, and toner transportability are obtained on the outer periphery thereof. Therefore, a coating layer made of a coating material to which a resin such as nylon or urethane, rough particles for ensuring appropriate surface roughness, or a conductive agent for ensuring conductivity is added is often provided.

  These developer-carrying rollers are used, for example, by providing portions where the shaft cores are exposed at both ends in order to be fixed and rotated on the bearing portion of the apparatus main body or the cartridge main body, for example. In the manufacturing process of the developer carrying roller, various measures are taken so that the shaft core exposed at both ends is not damaged, but if it is accidentally damaged, it must be handled as a defective product. This is because when a developer carrying roller with scratches on the shaft core exposed at both ends is incorporated into the main body of the apparatus or the card ridge main body, image defects due to rotation unevenness due to scratches on the shaft core body or the main body of the apparatus main body or the card ridge main body. This is because the bearing portion is shaved, shavings are generated, and troubles such as damage to the photoconductor occur.

  As a conventional technique that does not damage the shaft core body, a method of removing unnecessary rubber so that the shaft core body is not scratched by spraying ultra-high pressure water when removing unnecessary rubber has been proposed. (For example, Patent Document 1).

  In this method, when removing the rubber part at the end of the unnecessary shaft body, the rubber part of the required part and the shaft body are often damaged, and the finished rubber roll has the rubber end side away from the shaft body. It peels and becomes a so-called trumpet shape in which the rubber diameter at the end becomes thick. Moreover, it can be used only when the roller has fast reversibility with respect to water.

  As another method, while rotating the rubber roll, the wire (made of metal) is brought into contact with both end faces of the rubber part of the rubber roll to remove burrs, and after removing the burr of the rubber roll with the wire, the wrapping tape is attached to the shaft core It is made to contact and finish (for example, patent document 2).

In this method, unnecessary rubber portions can be efficiently removed. However, since a metal wire is used, there is a high possibility that the shaft core body is damaged depending on the material of the shaft core body.
JP-A-8-174500 Japanese Patent No. 3386591

  It is an object of the present invention to have no scratches on the exposed portion of the shaft core body, in particular, no convex scratches, without affecting the layers formed on the shaft core body such as an elastic layer. An object of the present invention is to provide a method for producing a conductive roller capable of obtaining a conductive roller.

  Another object of the present invention is to provide a conductive roller that is free from scratches, in particular, convex scratches, on the exposed portion of the shaft core.

According to the present invention, there is provided a conductive roller having a metal shaft core body and an elastic layer disposed on the outer periphery of the shaft core body, and having both ends in the longitudinal direction having a shaft core body exposed portion where the shaft core body is exposed. In the manufacturing method,
There is provided a method for manufacturing a conductive roller, comprising: a step of providing an elastic layer on an outer peripheral surface of the shaft core body other than the exposed portion of the shaft core; and a step of burnishing the exposed portion of the shaft core.

  In the burnishing process, it is preferable to use a burnishing roller having a surface roughness Rzjis of 2 μm or less in the burnishing process section.

  In the burnishing process, it is preferable to use a burnishing roller in which the burnishing processing part is longer than the exposed portion of the shaft core and the burnishing processing part has no seam.

According to the present invention, there is provided a conductive roller having a metal shaft core body and an elastic layer disposed on an outer periphery of the shaft core body, and having both ends in the longitudinal direction having a shaft core body exposed portion from which the shaft core body is exposed. ,
A conductive roller is provided in which the shaft core exposed portion is burnished.

  According to the present invention, the exposed portion of the shaft core body is not affected by or affected by the layer formed on the shaft core body, such as the elastic layer, and the exposed portion of the shaft core body is not damaged. A method of manufacturing a conductive roller capable of obtaining a roller is provided.

  In addition, the present invention provides a conductive roller that has no scratches, in particular no convex scratches, on the exposed portion of the shaft core.

  If the shaft core part exposed at both ends in the longitudinal direction of the conductive roller has a convex flaw, an image defect due to rotation failure may occur in the image forming apparatus. . In the present invention, by conducting burnishing treatment on the shaft core portion exposed at both ends in the longitudinal direction of the conductive roller, a conductive roller having no convex scratch on the shaft core exposed portion can be obtained. In addition, it can be burnished regardless of the layer formed on the shaft body, does not cause peeling or shape change of these layers to eliminate scratches, and regardless of the material of these layers, Scratches can be eliminated without depending on it.

  Hereinafter, a developer carrying roller (developing roller) will be described in detail as an example of the conductive roller of the present invention. However, in addition to the developer carrying roller, a contacted object such as a charging member, a transfer member, a cleaning member, or a charge removing member is used. The present invention can also be applied to a conductive roller that is electrically controlled.

  FIG. 1 shows an outline of a developer carrying roller according to an embodiment of the present invention. (A) is a schematic sectional view along the axis of the developer carrying roller, and (b) shows the developer carrying roller from the axial direction. FIG.

  The developer carrying roller in the form shown in this figure has an elastic layer 1b formed on a shaft core 1a and a coating layer 1c provided on the outer periphery thereof. There is no layer such as an elastic layer on the shaft core exposed portion 1a-1. Such a developer-carrying member may be obtained without forming an elastic layer or the like in the exposed portion of the shaft core, and after exposing any layer to the exposed portion of the shaft core, the exposed portion of the shaft core. Such a developer carrying member may be obtained by removing the upper layer.

  The length of the exposed portion of the shaft core is not particularly limited. When the developer carrying roller is incorporated in the process cartridge, the rotation accuracy is maintained, and a sufficient drive can be attached by attaching a gear. It can be determined as appropriate in consideration of the fact that sufficient conduction for providing the electric charge can be obtained.

  FIG. 2 shows a burnishing process in which a shaft core exposed portion 1a-1 existing at both longitudinal ends of the developer carrying roller 1 is sandwiched between a burnishing roller 3 and a support roller (backup roller) 4 that supports the shaft core exposed portion. FIG. 6 is a schematic view of a state where the state is viewed from the axial direction of the developer carrying roller.

  FIG. 3 is a schematic view of the above state seen from a direction perpendicular to the axis of the developer carrying roller.

[Vanishing processing]
The developer carrying roller 1 is provided with an elastic layer 1b and a surface coating layer 1c in this order on the shaft core 1a. In the manufacturing process, the surface of the shaft core exposed portion 1a-1 was damaged. In some cases, such an image is generated as an image defect due to a rotation failure in the image forming apparatus.

  In the present invention, for the developer carrying roller having a scratch on the surface of the exposed part of the shaft core of the developer carrying roller, only the exposed part of the shaft core is burnished by the burnishing roller, which causes image defects. It can be handled as a non-defective product by crushing the raised scratches on the surface of the shaft core. Also, in the final finishing process of the developer carrying roller, only the exposed part of the shaft core body is burnished for all the developer carrying rollers, so that image defects caused by scratches on the surface of the shaft core body are eliminated. It can be eliminated. That is, the developer carrying member having a scratch on the shaft core exposed portion may be selected and burnished, or all the developer carrying members to be manufactured may be burned without such sorting.

  In general, the shaft core body is often used after being plated on a steel material. In the present invention, the shaft core body is plated after sufficiently degreasing and removing the surfactant on the core metal surface to be plated. By using a cored bar and setting the pressing pressure of the burnishing roller at the time of burnishing to such an extent that does not cause plating peeling or the like, the burnishing can be performed without causing plating peeling or the like.

  As the burnishing processing method, a processing method using a burnishing roller used in known machining or the like can be used. From the viewpoint of excellently avoiding defective rotation and the like by crushing and smoothing the convex scratches on the shaft core body, the surface roughness Rzjis (ten-point average roughness defined in JIS B0601) of the burnishing roller is: It is preferably 2 μm or less, more preferably 0.5 μm or less.

  Further, the lower limit of the surface roughness Rzjis of the burnishing treatment part is not particularly limited in consideration of the smoothness of the surface of the core metal obtained by the burnishing process, but from the viewpoint of maintaining the smoothness of the surface of the burnishing roller. 0.05 μm or more is preferable.

  From the viewpoint of the smoothness of the surface of the shaft core exposed portion, it is preferable that the burnishing processing portion of the burnishing roller is longer than the shaft length of the shaft core exposed portion and that the processing portion of the burnishing roller is seamless.

  From the viewpoint of not affecting the layer provided on the shaft core body such as the elastic layer, the boundary between the shaft core body exposed portion 1a-1 and the elastic layer and the surface coating layer 1c end is shown in FIG. It is preferable to prevent the burnishing roller 3 and the backup roller 4 from coming into contact with the elastic layer and the end portions of the surface coating layer as shown in FIG. In this case, a slight part of the shaft core on the end side of the elastic layer and the surface covering layer cannot be burnished, but when the developer carrying roller is incorporated in the process cartridge, Since it is not used as a process cartridge casing or a drive gear, there is no particular problem.

  As shown in FIGS. 2 and 3, the burnishing treatment preferably uses at least a burnishing roller and a support roller that supports the exposed portion of the shaft core (use at least two rollers in total). Note that a burnishing roller can be used as the support roller, that is, burnishing can be performed using two or more burnishing rollers.

  If necessary, the number of burnishing rollers can be three or more. In this case, the diameter of the three or more burnishing rollers is preferably the same, and the burnishing roller to be disposed and the core metal to be processed The positional relationship is preferably such that the center of rotation of the burnishing roller is at equal intervals when the cored bar is the center of rotation.

  Further, the support roller itself may have a function of performing a burnishing process, but in the case of a simple support roller, the support roller is a material that can be pushed out without being deformed. Support rollers can be used.

  As the material of the burnishing roller, it is preferable to use a material whose hardness is higher than that of the shaft core. Specifically, cemented carbide such as carbon tool steel, high speed steel, alloy tool steel, and high carbon chrome bearing steel. Are preferred.

  The pressing pressure (processing pressure) of the burnishing roller during the burnishing process varies depending on the material of the shaft core to be processed, and can be set while measuring the change in surface roughness by the burnishing process.

  In general, during the burnishing process, the workpiece is immersed smoothly with cutting oil or the like, and the process is smoothly performed. In the present invention, however, the viewpoint of preventing the elastic layer and the surface coating layer of the developer carrying roller from being contaminated. From the time of the burnishing process, by causing the rotation speed of the core metal to follow the rotation of the burnishing roller, it is possible to suppress scratches caused by slipping on the core metal, so without using liquids such as oil, solvent, water, Can be processed. Alternatively, it is possible to use a liquid such as oil, a solvent, or water by masking the elastic layer and the surface coating layer of the developer carrying roller. In addition, if the solvent does not affect the elastic layer and the surface coating layer of the developer carrying roller and does not affect the physical properties of the developer carrying roller, it can be easily burnished without the need for masking. Examples of such a solvent include alcohol solvents and water, and it is preferable to quickly remove the solvent and the like adhering to the developer carrying roller by air blow after the burnishing process.

  Convex scratches on the exposed part of the shaft core are preferably erased by the burnishing process described above or Rzjis is 2 μm or less. On the other hand, there is no problem with indentations, even if an image with an indentation in the exposed part of the shaft core is incorporated in the process cartridge and drawn, since it does not cause rotation failure.

[Conductive roller]
As the shaft core 1a used in the present invention, a metal round bar such as iron, copper, stainless steel, aluminum and nickel can be used. From the standpoint of ease of cutting and maintaining the dimension and shape after cutting, free cutting steel containing iron as a main component is particularly preferable. Furthermore, the surface of these metal round bars may be subjected to a plating treatment within a range not impairing conductivity for the purpose of imparting rust prevention and scratch resistance.

The elastic layer 1b is made of a rubber material such as natural rubber, silicone rubber, urethane rubber, chloroprene rubber, neoprene rubber, isoprene rubber, nitrile butadiene rubber (NBR), and a conductive agent (carbon black, Graphite, conductive metal oxides, copper, aluminum, nickel, iron powder, etc.) or ionic conductive agents (alkali metal salts and ammonium salts) added thereto, conductive rubber, etc. can be used as appropriate. In this case, two or more conductive agents may be used in combination. The addition amount of the conductive agent is usually 2 to 20 parts by mass with respect to 100 parts by mass of the rubber material. In the case of a developer-carrying roller, in consideration of hardness and compression set, addition-reactive conductive silicone rubber is preferable, and the thickness of the elastic layer is usually preferably 1 to 6 mm. The conductivity of the elastic layer is preferably in the range of 10 ⁵ to 10 ⁷ Ω · cm, and the elastic modulus is not particularly limited as long as it is a range obtained with a normal rubber material.

  The coating layer may or may not be present. When the coating layer is a single layer, the thickness of the coating layer is preferably 8 μm or more in order to prevent bleed-out, and the flexibility of the elastic layer is not impaired. Is taken into consideration, it is preferable that the thickness is 100 μm or less. Moreover, when making a coating layer into a multilayer, it is preferable to make it the total thickness of each layer become the said range.

  The covering layer 1c can be formed using a resin material. Examples of the resin material include fluorine resin, nylon resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, and fluororubber-based thermoplastic elastomer. And polyester thermoplastic elastomers, polyamide thermoplastic elastomers, polybutadiene thermoplastic elastomers, ethylene vinyl acetate thermoplastic elastomers, polyvinyl chloride thermoplastic elastomers, and chlorinated polyethylene thermoplastic elastomers. These resin materials may be a homopolymer or a copolymer. These resin materials may be used alone or in combination of two or more.

  In the contact development method, the coating layer 1c is desired to be uniformly pressed against the photosensitive member of the developer carrying roller (developing roller), and a regulation blade that regulates the layer thickness of the toner on the developer carrying roller (developing roller). Both of them may be in contact with each other, and if a deformed trace remains, it will appear as an image defect. For this reason, the coating layer used for the developer carrying roller is formed by using a polyurethane resin because high compression set is required with respect to the environmental temperature used in a copying machine, a printer, or the like. preferable.

  Examples of the polyol compound used in the polyurethane resin used in the coating layer 1c include known polyols for polyurethane such as polyethylene glycol, tetramethylene glycol polyethylene diadipate, polyethylene butylene adipate, poly-ε-caprolactone diol, polycarbonate polyol, and polypropylene glycol. Can be mentioned.

  As the isocyanate compound, diisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and their burettes, isocyanurates and urethanes are preferably used. be able to. Particularly preferred isocyanate compounds are HDI and its burette-modified products, isocyanurate-modified products, urethane-modified products and the like. The longer the molecular chain of the isocyanate compound, the more the polyurethane coating layer having higher flexibility is generated.

  The covering layer 1c can be added with an appropriate amount of insulating particles to the resin material in order to ensure sufficient toner transportability. The insulating particles preferably have an average particle diameter of 3 μm to 100 μm, and more preferably have an average particle diameter of 5 μm to 30 μm.

  As the material of the insulating particles, for example, urethane particles, nylon particles, acrylic particles, silicone particles and the like can be used. The shape is preferably spherical.

  About the addition amount of insulating particle | grains, when the resin material in the coating material which forms a coating layer is 100 mass parts, it is preferable normally that insulating particles shall be 2-50 mass parts. When the amount of the insulating particles added is within this range, a coating layer surface having an appropriate toner transportability as a developing roller can be obtained.

  In the present invention, for the purpose of adjusting the electric resistance of the entire developer-carrying roller, the coating layer can contain conductive fine particles as long as it does not contaminate the photoreceptor. The conductive fine particles include fine particles of a conductive agent (carbon black, graphite, conductive metal oxide, copper, aluminum, nickel, iron powder, etc.) having various electron conduction mechanisms or an ionic conductive agent (alkali metal salt and ammonium salt). Can be used. Two or more of the above conductive agents may be used in combination. Moreover, it is preferable to add 5-100 mass parts of electroconductive fine particles normally with respect to 100 mass parts of resin materials. When the addition amount of the conductive fine particles is 5 parts or more, good conductivity can be imparted to the coating layer, and by adding a desired amount of conductive fine particles up to 100 parts by mass, the conductivity required as a process cartridge. It becomes possible to control the sex range almost. More preferably, the conductive fine particles are added in an amount of 15 to 30 parts by mass with respect to 100 parts by mass of the resin material.

  The coating layer 1c is prepared by adding the above-described resin material in a solvent such as an organic solvent or water and dissolving or diluting the resin material appropriately to disperse the conductive fine particles and insulating fine particles as appropriate. The liquid can be applied on the peripheral surface of the elastic layer and dried.

  Examples of the organic solvent that can be used for forming the coating layer 1c include methyl isobutyl ketone, methyl ethyl ketone, acetone, cyclohexanone ketones, aromatics such as xylene and toluene, esters such as n-butyl acetate and ethyl acetate, and tetrahydrofuran. , Ethers such as ethyl cellosolve, tetrahydropyran, and the like, but are not particularly limited thereto. Moreover, when resin etc. melt | dissolve, water etc. can be used as a solvent.

  A known method can be used to clean the surface of the elastic layer before coating, which is combined with a method of forming a coating layer by coating the coating liquid from the opposite side in the longitudinal direction of the end where the elastic layer material is injected. Therefore, even higher effects can be expected. Specific methods include, for example, spraying compressed air, contact with an adhesive tape, cleaning with an organic solvent that does not attack the elastic layer material, cleaning with high-pressure water, and cleaning with water.

  As a coating method, a method of selectively applying a coating liquid from vertical dip coating, ring coating, roll coating, or the like can be appropriately employed.

  When a pulverization step is added in the preparation of the coating liquid, a ball mill, a sand mill, a vibration mill, or the like can be used.

  Next, the film produced by the coating method as described above is dried. As a drying method, air drying without heating, heat drying, heat treatment up to the reaction temperature in the case of a thermosetting resin, etc. are used. It can be appropriately selected depending on the material.

[Process cartridge]
Next, an example of a process cartridge using a developer carrying roller according to an embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a sectional view showing a schematic configuration of an image forming apparatus using the process cartridge.

  The process cartridge includes a developer carrying roller that carries a developer in a state of being in contact with or pressed against a photosensitive drum as a latent image carrier that carries a latent image, and the developer carrying roller is attached to the photosensitive drum. A process cartridge that visualizes a latent image as a developer image by applying toner as a developer, and includes a photosensitive drum 21 as a latent image carrier, a charging device 22, a developer carrying roller 25, a developing blade 27, and a developing container. 34, a cleaning blade 30 is provided, and the conductive roller of the present invention is used as the developer carrying roller 25. The photosensitive drum 21 rotates in the direction of arrow A, is uniformly charged by a charging device 22 for charging the photosensitive drum 21, and the laser beam 23 is an exposure unit that writes an electrostatic latent image on the photosensitive drum 21. An electrostatic latent image is formed on the surface. The electrostatic latent image is developed by being provided with a toner 28 as a developer by a developing device 24 that is disposed in proximity to the photosensitive drum 21 and is held in a process cartridge that can be attached to and detached from the image forming apparatus main body. Visualized as a toner image.

  Development is so-called reversal development in which a toner image is formed on the exposed portion. The visualized toner image on the photosensitive drum 21 is transferred to a paper 33 as a recording medium by a transfer roller 29. The paper 33 to which the toner image has been transferred is subjected to a fixing process by the fixing device 32, discharged outside the device, and the printing operation is completed.

  On the other hand, the untransferred toner remaining on the photosensitive drum 21 without being transferred is scraped off by the cleaning blade 30 and stored in the waste toner container 31, and the cleaned photosensitive drum 21 repeats the above-described operation.

  The developing device 24 includes a developing container 34 that contains a non-magnetic toner 28 as a one-component developer, and a developer carrying member that is located in an opening extending in the longitudinal direction in the developing container 34 and is opposed to the photosensitive drum 21. And an electrostatic latent image on the photosensitive drum 21 is developed and visualized.

  The developer carrying roller 25 is in contact with the photosensitive drum 21 with a contact width. In the developing device 24, the supply roller 26 is in contact with the contact portion of the developing blade 27 with the surface of the developer carrying roller 25 in the developing container 34 on the upstream side in the rotation direction of the developer carrying roller 25, and It is rotatably supported.

  As the structure of the supply roller 26, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon or nylon are planted on the shaft core is used for supplying the toner 28 to the developer carrying roller 25 and for the undeveloped toner. It is preferable from the point of peeling off.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited at all by these Examples.

Example 1
<Shaft core>
Electroless nickel-phosphorous plating was applied to a round rod-shaped steel shaft core having a diameter of 8 mm to obtain a shaft core having a plating thickness of 6 μm.

<Production of elastic layer>
Next, an elastic layer made of conductive silicone rubber was formed on the shaft core. The shaft core is installed in a cylindrical mold with an inner diameter of 16 mm so as to be concentric with the mold cavity, and a mold having a top mold on both sides and a cylindrical mold placed between the tops is set in a molding machine. Then, liquid rubber was injected into the mold by an injection injection device. The injection conditions were an injection time of 10 seconds, and the amount of liquid rubber injected into the mold was 40 ml, which was injected at a constant rate of 4 ml / second. The liquid rubber used here is a platinum catalyst blended in a small amount in one liquid using liquid conductive silicone rubber (manufactured by Toray Dow Corning Co., Ltd., volume specific resistance 1 × 10 ⁶ Ωcm), and a curing agent on the other side. The two-component mixed addition reaction type was added.

  The liquid rubber injected into the mold is heated and cured with a hot plate in the molding machine, and after mold removal, secondary vulcanization is performed in an oven at 200 ° C. for 4 hours to form a cylindrical shape with a thickness of 4 mm around the shaft core. A developer carrying roller precursor having an elastic layer was obtained. In addition, the elastic layer was not provided in 15 mm from the both ends of the shaft core body.

<Preparation of coating layer>
Next, a coating layer was formed around the elastic layer. Urethane paint (trade name: NIPPOLAN N5033, manufactured by Nippon Polyurethane Co., Ltd.) is diluted with methyl ethyl ketone so that the solid content concentration becomes 10% by mass, and carbon black (trade name: MA100, manufactured by Mitsubishi Chemical Corporation) is used as the conductive agent. 70 parts by mass with respect to 100 parts by mass of the solid content of the paint, and urethane particles having an average particle size of 14 μm as insulating particles (trade name: Art Pearl C400, manufactured by Negami Kogyo Co., Ltd.) After adding parts by mass, 10 parts by mass of a curing agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) is added to 100 parts by mass of the solid content of the urethane paint, and the mixture is stirred and applied. A working solution was prepared.

  Next, this coating liquid is put into a circulator of a vertical dip coating apparatus, adjusted to a liquid temperature of 23 ± 1 ° C. and a liquid viscosity of 14.0 mPa · s, and a developer carrying roller precursor obtained by the above method. Is coated on the coating pallet, the coating liquid is applied in a vertical dip, air-dried at room temperature for 30 minutes, dried in an oven at 80 ° C. for 15 minutes, and further cured in an oven at 140 ° C. for 4 hours. And a developer carrying roller (shaft core exposed portions from both ends of the shaft core to 15 mm each) were obtained.

<Interim evaluation>
Next, the exposed parts of the shaft core at both ends of the developer-carrying roller obtained as described above are visually observed, and those with scratches on the surface of the shaft core are selected and incorporated into the process cartridge, and the normal environment The image was imaged below, and defects on the image were visually observed. As a result, an image defect caused by a scratch on the exposed portion of the shaft core was observed. The scratch on the shaft core was 10 μm on the convex side when the surface of the shaft core was used as a reference.

<Vanishing processing>
Next, remove the developer carrying roller from the process cartridge and expose the shaft core on both sides of the process card ridge, where image defects were found due to scratches on the exposed parts of the shaft core on both ends of the developer carrying roller. The burnishing process was performed on the part.

  Two burnishing rollers having a diameter of 150 mm, a length of 100 mm, and a surface roughness Rzjis of 0.2 μm are used, and the developer core roller exposed portion is sandwiched between the processing portions of the two burnishing rollers. The burnishing roller was rotated at 50 rpm and burnishing was performed for 10 seconds. At this time, the burnishing roller was separated from the elastic layer and the coating layer by 1.0 mm.

  The developer-carrying roller that has been burnished is re-installed in the process cartridge, imaged in a normal environment (20 ° C, relative humidity 65%), and defects on the image were observed visually. Was not particularly recognized. The scratch on the shaft core body was 0.36 μm on the convex side when the surface of the shaft core body was used as a reference by burnishing.

  As described above, by performing the burnishing process, it was possible to prevent the developer carrying roller in which the image defect occurred from occurring.

(Example 2)
100 roller-shaped developer carrying rollers were prepared in the same manner as in Example 1, and the burnishing process was performed on all the developer carrying rollers in the same manner as in Example 1 without performing an intermediate evaluation.

  Next, 100 developer carrying rollers obtained as described above were incorporated into a process cartridge, imaged in a normal environment, and defects on the image were visually observed. There were no image defects due to the scratches on the part.

  As described above, by applying a burnishing process at the end of the developer carrying roller manufacturing process, it is possible to eliminate the developer carrying roller that causes image defects due to scratches on the exposed part of the shaft core. It was.

(Example 3)
The same test as in Example 1 was performed except that the surface roughness Rzjis of the two burnishing rollers used was both set to 2.0 μm.

  As in Example 1, the developer carrying roller after finishing the burnishing process was again incorporated into the process cartridge, the image was printed in a normal environment, and the defects on the image were visually observed. As a result of visual observation, no image defects caused by scratches on the exposed portion of the shaft core were found.

  The scratch on the shaft core body was 2.0 μm on the convex side when the surface of the shaft core body was used as a reference by burnishing.

Example 4
The same test as in Example 1 was performed except that the surface roughness Rzjis of the two burnishing rollers used was set to 2.3 μm.

  As in Example 1, the developer-carrying roller that has been burnished is re-installed in the process cartridge, the image is printed in a normal environment, and the defects on the image are visually observed. Although slight density unevenness occurred at the same pitch as the circumference of the developer carrying roller at the position, it was within the allowable range.

  The scratch on the shaft core body was 2.4 μm on the convex side when the surface of the shaft core body was taken as a reference by burnishing.

  The conductive roller according to the present invention can be suitably used as a conductive roller used in an image forming apparatus employing an electrophotographic system.

It is a schematic sectional drawing which shows the example of the developing agent carrying | support roller which is one form of the electroconductive roller of this invention. FIG. 6 is a schematic view of a state where a burnishing process is performed as viewed from an axial direction of a developer carrying roller. FIG. 4 is a schematic view of a state where burnishing is performed as viewed from a direction perpendicular to the axis of a developer carrying roller. 1 is a schematic configuration diagram of an image forming apparatus using a process cartridge having a developer carrying roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developer carrying roller 1a Shaft core body 1a-1 Shaft core body exposed part 1b Elastic layer 1c Covering layer 3 Burnishing roller 4 Backup roller 21 Latent image carrier (photosensitive drum)
DESCRIPTION OF SYMBOLS 22 Charging device 23 Laser beam 24 Developing device 25 Developer carrying roller 26 Supply roller 27 Developing blade 28 Developer (toner)
29 Transfer roller 30 Cleaning blade 31 Waste toner container 32 Fixing device 33 Paper 34 Developer container

Claims (4)

In a method for manufacturing a conductive roller having a shaft body made of metal and an elastic layer disposed on the outer periphery of the shaft core body, and both ends in the longitudinal direction have exposed portions of the shaft core body where the shaft core body is exposed,
A method for producing a conductive roller, comprising: a step of providing an elastic layer on an outer peripheral surface of the shaft core body other than the exposed portion of the shaft core; and a step of burnishing the exposed portion of the shaft core.   The method according to claim 1, wherein a burnishing roller having a surface roughness Rzjis of 2 μm or less is used for the burnishing process.   3. The method according to claim 1, wherein the burnishing process uses a burnishing roller having a burnishing section longer than the exposed portion of the shaft core and having a seamless seam in the burnishing section. In a conductive roller having a shaft body made of metal and an elastic layer disposed on the outer periphery of the shaft core body, and having both ends in the longitudinal direction having exposed portions of the shaft core body where the shaft core body is exposed,
A conductive roller, wherein the exposed portion of the shaft core is burnished.

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