JP2011230030A - Method for manufacturing elastic roller for electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an elastic roller for electrophotography capable of continuously manufacturing the elastic roller for electrophotography with high shape accuracy without the interruption at a production cycle even when a coating material leaks out from a coating head during molding standby.SOLUTION: In the method for manufacturing of the elastic roller for electrophotography having an axis body and a coating film on the outer peripheral surface thereof, after the coating material is applied on the axis body, a process for moving the lower supporting shaft upward further to remove the axis body coated with the coating material and a ring seal from a center hole is executed without making a contact between a lower supporting shaft and a lower surface of the ring seal.

Description

  The present invention relates to a method for manufacturing an electrophotographic elastic roller.

  In recent years, the needs for colorization and high image quality of electrophotography have increased, and there has been a strict demand for higher accuracy of the outer dimensions of the electrophotographic elastic roller and uniformity of surface roughness. For example, in the contact-type development method, the developing roller is in contact with the surface of the photosensitive drum. Therefore, if the outer dimensions are not accurate, the nip width and the nip pressure between the photosensitive drum and the developing roller will fluctuate, and density unevenness will An image defect may occur.

  In order to meet this demand for high shape accuracy, various molding methods such as molding using a mold and molding by extrusion have been studied as methods for producing various electrophotographic elastic rollers. In addition, spray coating methods, dip coating methods, roll coating methods, blade coating methods, and the like have been studied as methods for applying a paint to the shaft core. However, in the spray coating method, if the viscosity of the paint is high, it becomes difficult to atomize, so it is necessary to keep the viscosity of the paint low. Further, in the blade coating method or roll coating method, when the blade or roll at the end of coating is retracted, a thicker part than the other part occurs in a part of the coating film on the cylindrical body due to the viscosity of the coating liquid. In particular, when the viscosity of the coating liquid is high, this influence tends to increase.

  Under such circumstances, a method of applying a high-viscosity coating material to a shaft core using an annular coating head has been disclosed (Patent Document 1). In this method, the shaft core body is coaxially arranged inside the coating head, and the coating head is applied to the shaft core body while discharging paint to the gap between the inner peripheral surface of the coating head and the shaft core body. The paint is applied to the outer peripheral surface of the shaft core body by relatively moving in the axial direction of the shaft core body. In this coating method, even if the viscosity of the paint is high, the paint is pressed against the surface of the shaft core through the coating head, and the coating is performed while keeping the paint in a certain thickness. This makes it possible to apply the coating directly and satisfactorily and uniformly to the surface of the shaft core even under various coating conditions such as a greater variety of coating materials and coating film thicknesses.

  However, in the method of applying a high-viscosity paint with the coating head, the liquid may not be drained at the end of the discharge of the paint, and the paint may remain inside the coating head. As a means to prevent the paint from remaining, the paint inside the coating head is scraped off with a ring seal at the end of discharge (Patent Document 1), or the liquid pressure in the annular slit is reduced to a negative pressure at the end of discharge. A means for doing this is disclosed (Patent Document 2).

  However, if an electrophotographic elastic roller is repeatedly formed using the coating head, the coating head discharges the paint in order to take out the workpiece that has been coated and place the shaft core used for the next molding. Must be temporarily stopped (molding standby). Even if the paint inside the coating head is scraped off at the end of discharge due to the expansion of the paint compressed during discharge during the molding waiting time and the flow of paint remaining after the end of discharge, May leak out. Although the above-mentioned conventional example discloses means for improving the liquid drainage in the coating head at the end of ejection, the paint from the annular slit at the time of molding standby that occurs when the elastic roller for electrophotography is repeatedly molded is disclosed. It does not mention any issues related to leakage.

JP 2007-130589 A JP 2003-190870 A

  An object of the present invention is a manufacturing method of an electrophotographic elastic roller having a shaft body and a coating film on the outer peripheral surface thereof, and even if the paint leaks from the coating head during molding standby, an electronic device with high shape accuracy is provided. It is an object of the present invention to provide an electrophotographic elastic roller manufacturing method capable of continuously manufacturing a photographic elastic roller without interruption of a manufacturing cycle.

According to the present invention, the shaft core and a method for producing an electrophotographic elastic roller having a coating film on the outer peripheral surface thereof,
(1) An annular slit is formed on the inner peripheral surface of the center hole outside the shaft core supported along the vertical direction by the upper support shaft and the lower support shaft having a diameter larger than the diameter of the shaft core. Arranging the coating head having a predetermined gap between the peripheral surface of the shaft core and the annular slit;
(2) inserting an annular first ring seal centered on a hole having an inner diameter smaller than the diameter of the lower support shaft into the center hole from above and positioning it directly below the annular slit;
(3) The upper surface of the first ring seal is adjusted so that the upper end of the coating film forming region of the shaft core is the same as the upper surface of the first ring seal or does not exceed the upper surface of the coating head. A step of being positioned so as to be higher than
(4) The paint is discharged from the annular slit onto the upper surface of the first ring seal, and the gap between the peripheral surface of the shaft core and the annular slit is filled with the paint, and the lower support shaft is moved vertically upward. And applying the paint on the peripheral surface of the shaft core by moving the shaft core upward with respect to the annular slit, and
(5) moving the lower support shaft further vertically upward to disengage the shaft core body coated with the paint and the first ring seal from the center hole;
In the step (5), the lower support shaft is moved vertically upward without contacting the lower support shaft and the lower surface of the first ring seal.

  According to the present invention, it is possible to repeatedly and continuously manufacture an electrophotographic elastic roller with high shape accuracy without interrupting the manufacturing cycle.

It is a schematic structure figure showing an example of the coating device concerning the present invention. It is a schematic sectional drawing which shows an example of the coating head which can be used for this invention. It is a figure explaining the conventional process of applying a coating material to the outer peripheral surface of a shaft core. It is explanatory drawing that the shape precision of the elastic roller for electrophotography deteriorates by adhesion of the coating material to a lower support shaft. It is a figure explaining the process of applying a coating material to the outer peripheral surface of a shaft core body in this invention. It is a figure explaining a process when the 2nd ring seal of the present invention is used. 1 is a schematic configuration diagram of an image forming apparatus including a photographic elastic roller according to the present invention.

  A schematic configuration of a coating apparatus having a coating head is shown in FIG. In the coating apparatus shown in FIG. 1, a column 2 is attached substantially vertically on a gantry 1, and a precision ball screw 3 is attached to the column 2 substantially vertically. The precision ball screw 3 and the stage 5 are connected to the guide 4 and the precision ball screw 3 so that the rotary motion is transmitted from the servo motor 6 through the pulley 7 so that the precision ball screw 3 and the stage 5 can be moved up and down. The column 2 is provided with an annular coating head 9 that discharges paint onto the outer peripheral surface of a cylindrical shaft body 8. Further, a bracket 10 is attached to the stage 5, and an upper support shaft 11 that holds the shaft core body 8 and a lower support shaft 12 having a diameter larger than the diameter of the shaft core body are attached to the bracket 10.

  The center of the center hole of the coating head 9 and the shaft centers of the shaft core 8, the upper support shaft 11, and the lower support shaft 12 are adjusted so as to be substantially concentric along the vertical direction. The paint supply port 13 is connected to a paint supply valve 15 via a paint transport pipe 14. The paint supply valve 15 is provided with a mixing mixer, a paint supply pump, a paint metering / dispensing device, a paint tank, and the like in front of it, so that a certain amount of paint can be ejected. A certain amount of paint is measured from a paint tank by a paint dispensing apparatus and mixed by a mixing mixer. Thereafter, the paint is sent from the paint supply valve 15 to the coating head 9 via the pipe 14 by the paint supply pump.

  FIG. 2 is a schematic cross-sectional view of an example of a coating head. The coating head has an annular slit 18 on the inner peripheral surface of the center hole 16, and paint is discharged from the opening 19 of the annular slit 18. The width of the opening 19 of the annular slit 18 is usually set to 0.5 or more and 2.0 mm or less. The length 17 from directly below the opening of the annular slit to the lower surface of the coating head is an important point in the present invention, and details will be described later.

  Next, a conventional process of applying a paint to the outer peripheral surface of the shaft core body using the coating head will be described with reference to FIG. At the time of molding standby, the system is on standby with the lower support shaft protruding from vertically above the coating head ((a) of FIG. 3). The shaft core body is passed through the center hole of the annular first ring seal 20 having an inner diameter smaller than the diameter of the lower support shaft, and the shaft core body is vertically aligned with the upper support shaft and the lower support shaft. (B) in FIG. 3, the shaft core body, the upper support shaft, and the lower support shaft are moved vertically downward. Then, the first ring seal 20 is pushed into the coating head by the upper support shaft, and the first ring seal 20 is mounted at a position immediately below the annular slit ((c) of FIG. 3).

  Note that the outer diameter of the first ring seal is preferably the same as the diameter of the central hole of the coating head so that the outer peripheral surface thereof can contact the inner peripheral surface of the coating head. As a result, the first ring seal is not moved by the discharge pressure of the paint discharged from the annular slit, and the first ring seal can be firmly held at a position directly below the annular slit. If the discharge pressure of the paint is very large and the first ring seal moves during paint discharge, the diameter of the center hole of the coating head below the annular slit is made small, and the first ring seal is moved from the bottom. It may be supported.

  The shaft core is moved so that the upper end of the coating formation area of the shaft core is the same as the upper surface of the first ring seal or above the upper surface of the first ring seal within a range not exceeding the upper surface of the coating head. ((D) of FIG. 3). By discharging the paint from the annular slit onto the upper surface of the first ring seal and filling the gap between the peripheral surface of the shaft core body and the annular slit with the paint, the shaft core body is moved vertically upward to move the circumference of the shaft core body. A paint is applied to the surface ((e) of FIG. 3). In order to make the thickness of the paint constant, the discharge amount from the annular slit and the supply amount from the paint supply pump are made constant. During the discharge of the coating material, only the shaft core body moves and the first ring seal is held at a position immediately below the annular slit, so that the discharged coating material can be prevented from leaking from vertically below the coating head.

  The lower support shaft is further moved vertically upward, and the shaft core body and the first ring seal coated with the paint are separated from the center hole of the coating head. ((F) of FIG. 3). At this time, since the outer diameter of the first ring seal is the same as the diameter of the center hole of the coating head, the paint on the inner peripheral surface of the coating head is scraped off.

  The shaft core body and the first ring seal that are extruded vertically above the coating head are removed from the upper support shaft and the lower support shaft, and the coating film 21 of the coating material is cured by heat treatment to form an elastic layer. And On the other hand, in the coating apparatus, the lower support shaft protrudes from the vertical upper side of the coating head until the shaft core and the first ring seal used for the next molding are newly held by the upper support shaft and the lower support shaft. Waiting ((a) of FIG. 3).

  However, in a normal manufacturing method in which a plurality of elastic rollers for electrophotography are formed, the expansion of the paint compressed at the time of discharge during this standby and the flow of the paint remaining after the end of the discharge cause the annular slit to Paint may leak out. If the paint leaks from the annular slit, the paint adheres to the upper support shaft, the lower support shaft, and the shaft core, and the shape accuracy of the formed electrophotographic elastic roller deteriorates. A mechanism for deteriorating the shape accuracy of the electrophotographic elastic roller by the coating material adhering to the lower support shaft will be described with reference to FIG.

  During the waiting time until the next molding starts after the shaft core body and the first ring seal to which the paint has been applied are removed from the upper support shaft and the lower support shaft, the paint on the annular slit leaks from the annular slit due to the above factors ( FIG. 4A). The first ring seal is pushed into the coating head by the upper support shaft, and when the first ring seal is mounted at a position immediately below the annular slit, the paint leaked from the annular slit by the first ring seal is scraped off (FIG. 4). (B)). When the lower support shaft is moved vertically upward to disengage the shaft core body coated with the paint and the first ring seal from the center hole of the coating head, the first ring is processed in the step (b) of FIG. The first ring seal and the lower support shaft are brought into close contact with each other through the paint scraped off ((c) of FIG. 4). In this state, if the shaft core body coated with the paint and the first ring seal are to be removed from the lower support shaft, the first ring seal and the lower support shaft are in close contact with each other by the paint. The paint is pulled downward and the shape deteriorates ((d) in FIG. 4).

  In the present invention, in order to solve the above-described problems, the lower support shaft and the first ring seal are removed when the shaft core body and the first ring seal coated with the paint are separated vertically from the center hole of the annular head. Avoid contact with the bottom surface.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

  A series of steps of the present invention will be described in detail with reference to FIG.

  FIG. 5 shows the steps (a to c) of FIG. 5 in which the first ring seal scrapes away the paint leaked from the annular slit when the first ring seal is mounted at a position immediately below the annular slit. 4 (a) to (b). Conventionally, after discharging the paint, the lower support shaft is pushed out by contacting the first ring seal ((c) in FIG. 4). In the present invention, the lower support shaft and the first ring seal are not in contact with each other. Is removed from the center hole of the coating head (from (e) to (f) of FIG. 5). This is achieved by lifting the first ring seal vertically upward using the repulsive force of the magnet or the pressure of the gas. In particular, it is preferable to remove the first ring seal from the center hole of the coating head by using gas pressure because the configuration of the coating apparatus becomes simple.

  In the present invention, since the lower support shaft does not contact the first ring seal, the first ring seal and the lower support shaft do not come into close contact via the paint scraped off by the first ring seal. Therefore, the shaft core body and the first ring seal to which the paint has been applied can be removed cleanly from the lower support shaft ((g) in FIG. 5).

  In order to use the gas pressure to lift the first ring seal vertically upward, it is necessary to apply pressure to the lower surface of the first ring seal. One of the means is to apply the diameter of the lower support shaft. For example, the diameter of the central hole of the head may be approximately the same. By doing so, a closed space is formed by the first ring seal, the inner wall of the center hole of the coating head, and the upper surface of the lower support shaft in the process of moving the lower support shaft vertically upward after finishing the discharge of the paint. ((E) of FIG. 5). When the lower support shaft is further moved vertically upward, the pressure in the closed space increases, and the first ring seal can be lifted vertically upward ((f) in FIG. 5).

  The pressure in the closed space can be adjusted by adjusting the length 17 from the position immediately below the opening of the annular slit to the lower surface of the coating head. For example, when the pressure in the closed space is insufficient and the first ring seal cannot be lifted, the length from just below the opening of the annular slit to the lower surface of the coating head may be increased. By doing so, since the volume of the closed space formed when the upper surface of the lower support shaft enters the center hole of the coating head increases, the compressibility of the gas when the lower support shaft further moves vertically upward And the pressure in the closed space is increased. On the other hand, when the pressure in the closed space is too high, if the length 17 from just below the opening of the annular slit to the lower surface of the coating head is shortened, the gas compressibility decreases and the pressure in the closed space is weakened. be able to.

  A simple prediction can be made by calculating as follows how much the length from the position immediately below the opening of the annular slit to the lower surface of the coating head should be. First, when the lower support shaft moves vertically upward and the upper surface of the lower support shaft and the lower surface of the coating head become the same, the upper surface of the lower support shaft, the inner wall of the center hole, and the first ring seal are closed. The volume V1 of the space is calculated. Moreover, let the pressure (normal pressure) of the closed space at that time be P1. Next, the force required for the first ring seal attached to the center hole of the coating head to start moving is measured, and the force required to lift the first ring seal from the area of the lower surface of the first ring seal is measured. Calculate the pressure P2. When P1, V1, and P2 are obtained, the volume V2 of the closed space when Boyle's law P1 · V1 = P2 · V2 becomes P2 can be calculated. Since the position of the upper surface of the lower support shaft in the center hole of the coating head that becomes V2 can be calculated from the obtained V2, the length from the position immediately below the opening of the annular slit to the lower surface of the coating head can be calculated with reference to this value. You just need to set it.

  In the present invention, the second ring seal 22 can be attached to the lower support shaft instead of making the diameter of the lower support shaft substantially the same as the diameter of the center hole of the coating head. The second ring seal 22 is below the lower surface of the coating head before discharging the paint, but is inserted into the center hole of the coating head by moving the lower support shaft vertically upward during or after discharging. It is attached to the position where it is done. After the discharge of the paint, when the lower support shaft moves vertically upward, the second ring seal 22 is inserted into the center hole of the coating head, and the second ring seal 22, the inner wall of the center hole, and the first ring seal A closed space is formed. By moving the first ring seal above the center hole using the pressure in the closed space, the first ring seal can be lifted vertically upward without contacting the lower support shaft and the lower surface of the first ring seal. (FIG. 6).

  The material of the second ring seal is not particularly limited. Particularly, when the diameter of the second ring seal is larger than the diameter of the central hole of the coating head, elastic rubber or synthetic resin is preferable so as not to damage the coating head. Examples of the rubber include NBR, EPDM, BR, SBR, fluorine rubber, acrylic rubber, epichlorohydrin rubber, and silicone rubber. Examples of the synthetic resin having elasticity include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyacetal, polybutylene terephthalate, polyethylene terephthalate, polymethyl methacrylate, polyamide, polycarbonate, polyimide, and fluororesin.

  The diameter of the second ring seal is preferably 8% to 30% when inserted into the center hole of the coating head in order to form a good closed space. By setting the crushing margin within the above range, the minimum stress necessary for forming the closed space can be obtained, and stress cracking of the second ring seal can be prevented.

  In the present invention, the lower support shaft can be provided with an injection means for injecting compressed gas at a position vertically above the second ring seal. In the process of moving the first ring seal above the center hole of the coating head using the pressure in the closed space, the pressure in the closed space is adjusted by injecting compressed gas from the injection means provided on the lower support shaft. can do. This is useful when a very large pressure is required to lift the first ring seal or when the length from the position immediately below the annular slit to the lower surface of the coating head cannot be changed. The injection of the compressed gas is preferably started when the upper surface of the lower support shaft enters the center hole of the coating head and stopped when the first ring seal is pushed vertically upward of the coating head. The injection pressure of the compressed gas should be higher than the pressure required to lift the first ring seal, but if it is too high, the first ring seal will be lifted more than necessary, and the shape of the lower end of the coating will collapse. The shape accuracy may deteriorate.

  The coating material applied to the outer peripheral surface of the shaft core body becomes an elastic layer by being cured. Since the applied paint has adhesiveness, it is preferable to perform the heat treatment by a non-contact heat treatment method. Examples of the non-contact heat treatment method include an infrared heating method, a hot air heating method, a nichrome heat heating method, and an induction heating method. In particular, infrared heating is preferred because the apparatus is simple and the coating film can be uniformly heat-treated in the axial direction. The heat treatment temperature of the coating film surface depends on the paint used, but when infrared heating is performed, the output of the infrared heating device and the distance from the coating film may be adjusted according to the heat treatment temperature. When hot air heating is performed, the temperature and direction of the hot air may be adjusted. Further, the elastic layer may be further heat-treated and secondarily cured for the purpose of stabilizing physical properties after curing of the elastic layer and removing reaction residues and unreacted low molecular components in the elastic layer.

  Examples of the material constituting the shaft core include the following materials. Alloys of iron, steel, aluminum, titanium, copper and nickel, stainless steel containing these metals, alloys of duralumin, brass and bronze, as well as composite materials in which carbon black and carbon fibers are solidified with plastic are known to exhibit rigidity and conductivity. Material. Further, the shape may be a columnar shape or a cylindrical shape having a hollow at the center.

The rubber component forming the paint is not particularly limited, but it is preferable to use an addition reaction type silicone rubber for the following reasons.
・ Low compression set despite low hardness compared to other general-purpose rubber.
・ Excellent workability.
-Good dimensional stability due to the absence of by-products associated with the curing reaction.
-The physical properties after curing are stable.
The addition reaction type liquid silicone rubber is cured by an addition reaction between a polysiloxane containing an alkenyl group and a hydrogen polysiloxane containing a hydrosilyl group in the presence of a platinum catalyst.

  Although it does not specifically limit as molecular weight of the polysiloxane containing an alkenyl group, 10,000 or more and 500,000 or less are preferable. It is desirable that the polysiloxane has at least two alkenyl groups in one molecule. Although the kind of alkenyl group is not particularly limited, at least one of a vinyl group and an allyl group is preferable, and a vinyl group is particularly preferable because of its high reactivity with active hydrogen.

  In addition, the molecular weight in this invention is a weight average molecular weight when measured by gel permeation chromatography (GPC). That is, toluene as a solvent was allowed to flow through a column stabilized in a 40 ° C. heat chamber at a flow rate of 0.5 ml per minute, and 50 to 200 μl of a sample solution adjusted to 0.1 to 0.3% by mass was injected. And the weight average molecular weight of the sample was computed from the calibration curve created with several types of monodisperse polystyrene standard samples.

  The hydrogen polysiloxane containing a hydrosilyl group serves as a crosslinking agent for the addition reaction in the curing process. The number of silicon-bonded hydrogen atoms in one molecule is 2 or more, and preferably 3 or more in order to optimally carry out the curing reaction. The molecular weight of the hydrogen polysiloxane is not particularly limited, but is preferably 1000 or more and 10,000 or less, and particularly preferably 1000 or more and 5000 or less with a relatively low molecular weight in order to appropriately perform the curing reaction.

  The blending amount of the hydrogenpolysiloxane of the addition reaction type liquid silicone rubber in the present invention is such that the number of hydrosilyl groups in the hydrogenpolysiloxane is 1.0 to 3.0 times the number of alkenyl groups in the polysiloxane. It is preferable to be within. If it is less than 1.0 times, the crosslinking of the silicone rubber is reduced and the compression set may be deteriorated. On the other hand, when it exceeds 3.0 times, excessively unstable hydrosilyl groups remain, which is not preferable because the hardness and current of the electrophotographic elastic roller may change over time.

  As the catalyst for the addition reaction type liquid silicone rubber, a platinum catalyst that exhibits a catalytic action in the addition reaction of polysiloxane and hydrogen polysiloxane can be used. Specific examples thereof include chloroplatinic acid, platinum olefin complexes, platinum vinylsiloxane complexes, and platinum triphenylphosphine complexes.

  Regarding the blending amount of the catalyst, the platinum element amount is preferably 1 ppm or more and 1000 ppm or less with respect to 100 parts by mass of the polysiloxane. However, it is not limited to this range, and is appropriately selected depending on the target pot life, curing time, product shape, and the like.

  Conductive agents added for the purpose of imparting conductivity to the elastic layer include carbon black, graphite, conductive metal oxides, copper, aluminum, nickel, iron powder, or alkali metal salts that are ionic conductive agents, and ammonium salts. These fine particles can also be used. Among these, carbon black can be suitably used because it is relatively easily available.

  Furthermore, according to the specific use of the electrophotographic elastic roller, a non-conductive filler can be appropriately blended as a component necessary for the function required for the elastic layer itself. Non-conductive fillers include diatomaceous earth, quartz powder, dry silica, wet silica, titanium oxide, zinc oxide, aluminosilicate, calcium carbonate, zirconium silicate, aluminum silicate, talc, alumina and iron oxide.

  In this invention, the resin layer according to a use can also be provided on the outer periphery of the elastic layer formed as mentioned above. Examples of the material for forming the resin layer include various polyamides, fluororesins, hydrogenated styrene-butylene resins, urethane resins, silicone resins, polyester resins, phenol resins, imide resins, and olefin resins.

  In the resin layer, fine particles having a volume average particle diameter of 1 to 20 μm can be dispersed in accordance with individual applications. Examples of such fine particles include polymethyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles.

  The resin layer may contain a conductive agent in order to adjust the electrical resistance of the entire electrophotographic elastic roller. Conductive agents include carbon black, graphite, conductive metal oxides, copper, aluminum, nickel, iron powder, or alkali metal salts that are ionic conductive agents, and ammonium salts, which are conductive agents having various electron conduction mechanisms. Can be used.

  The material constituting these resin layers can be dispersed using a conventionally known dispersing device using sand mill, paint shaker, dyno mill, or pearl mill beads. A method for coating the obtained dispersion is not particularly limited, but a spray coating method or a dipping method is preferable because the operation is simple.

  Next, an example of an image forming apparatus having the electrophotographic elastic roller of the present invention will be described with reference to FIG.

  The image forming apparatus shown in FIG. 7 has one electrophotographic cartridge 23 for forming yellow, cyan, magenta, and black images, respectively, and is provided in a tandem manner.

  The developing device 24 includes a developing roller 26 disposed opposite to the photosensitive drum 25 and a developing container 28 containing a developer 27. Further, the developer 27 is supplied to the developing roller 26 and scrapes off the developer 27 that is not used for development and remains on the developing roller 26. A developing blade 30 that regulates and frictionally charges is provided.

  The photosensitive drum 25 is uniformly charged to a predetermined polarity and potential by the charging roller 31. The surface of the photosensitive drum 25 charged as a beam 32 according to image information is irradiated to form an electrostatic latent image. Next, the developer 27 uniformly coated on the developing roller 26 by the bias applied to the developing blade 30 on the formed electrostatic latent image is supplied from the developing roller 26, and the developer image is formed on the surface of the photosensitive drum 25. It is formed. Here, the bias applied to the developing blade 30 is generally a voltage several hundred volts higher than the bias of the developing roller 26.

  In the image transfer apparatus, a transfer conveyance belt 33 is stretched around a driving roller 34, a tension roller 35, and a driven roller 36, and a transfer roller 37 is installed inside the transfer conveyance belt 33 at a position facing the photosensitive drum 25. . Then, by applying a bias to the electrostatic adsorption roller 38, the transfer material 39 is electrostatically adsorbed to the outer peripheral surface of the transfer conveyance belt 33 and conveyed. When the transfer material 39 is conveyed to the transfer position, a bias having a polarity opposite to that of the developer image on the surface of the photosensitive drum 25 is applied to the transfer roller 37. As a result, the developer image is transferred to the transfer material 39.

  The transfer material 39 onto which the developer image has been transferred is sent from the transfer conveyance belt 33 to the fixing device 40, where the developer image is fixed on the transfer material 39, and printing is completed. On the other hand, the photosensitive drum 25 after the transfer of the developer image to the transfer material 39 is further rotated, and the surface of the photosensitive drum 25 is cleaned by the cleaning device 41.

  The electrophotographic elastic roller of the present invention can be used for the developing roller, charging roller, transfer roller, fixing roller, pressure roller, and driving roller. In addition to the image forming apparatus described above, the image forming apparatus can be used for an intermediate transfer type image forming apparatus.

  The present invention will be described more specifically with reference to the following examples. The present invention is not limited to the following examples.

[Formation of elastic roller for electrophotography]
Addition type liquid silicone rubber: "XE15-645" (trade name, manufactured by Momentive Performance Materials Japan GK) carbon black: "Raven 890" (trade name, manufactured by Columbian Chemical Co.) 10 mass Parts were blended. Similarly, addition type liquid silicone rubber: “XE15-645” (trade name, manufactured by Momentive Performance Materials Japan G.K.) Carbon B: “Raven890” (trade name, Columbia Chemical Co., Ltd.) (Made) 10 mass parts was mix | blended. Liquid A and liquid B were set in a paint tank attached to the coating apparatus, sent to a static mixer using a paint supply pump, and mixed at a mass ratio of 1: 1. This was used as a paint.

  For forming the elastic layer, the coating apparatus shown in FIG. 1 was used. The diameter of the center hole 16 of the coating head is 12.6 mm, the width of the opening 19 of the annular slit is 1.5 mm, and the length 17 from directly below the opening of the annular slit to the lower surface of the coating head is 30.0 mm. . The diameter of the upper support shaft was 10.0 mm, and the diameter of the lower support shaft was 12.5 mm.

  A shaft core of SUS304 having a diameter of 6.0 mm and a length of 250.0 mm has an annular shape whose inner diameter is 6.2 mm, outer diameter is 12.6 mm, thickness is 1.0 mm, and the material is polytetrafluoroethylene. It passed through the first ring seal and was held by the upper support shaft and the lower support shaft. Next, the shaft core, the upper support shaft, and the lower support shaft are moved vertically downward, and the upper ring is used to align the lower surface of the opening of the annular slit with the upper surface of the first ring seal. Installed. Note that the gauge pressure required to lift the first ring seal was 0.1 MPa.

  After the upper end of the coating film forming region of the shaft core was moved 5.0 mm above the upper surface of the first ring seal, the coating material was discharged from the annular slit onto the upper surface of the first ring seal at a flow rate of 840 mm 3 / sec. Simultaneously with the discharge of the paint, the shaft core was raised vertically upward at 10 mm / sec, and the paint was applied to the outer peripheral surface of the shaft core.

  The upper support shaft and the lower support shaft were moved vertically upward even after finishing the discharge of the paint, and the shaft core body and the first ring seal to which the paint was applied were pushed out onto the coating head. In addition, although the coating material adhered to the extruded lower surface of the first ring seal, the lower support shaft and the first ring seal were not in contact with each other directly or through the coating material. The shaft core body and the first ring seal coated with the paint extruded from the coating head were removed from the upper support shaft and the lower support shaft, and were cured by heat treatment.

  For the heat treatment, an infrared heating lamp: “HYL25” (trade name, manufactured by Heibeck Co., Ltd.) is disposed so that the temperature of the paint surface is 130 ° C. (output 780 W, distance between the lamp and the paint surface is 60 mm). The sample was heated for 5 minutes while rotating in the circumferential direction at 60 rpm.

  Thereafter, the shaft core and the first ring seal were again held by the upper support shaft and the lower support shaft, and the above steps were repeated to form a total of 500 electrophotographic elastic rollers.

[Shape accuracy of elastic roller for electrophotography]
In order to evaluate the shape accuracy of the electrophotographic elastic roller, the outer diameter difference in the longitudinal direction of the electrophotographic elastic roller was measured. A non-contact laser length measuring device: “LS-5000” (trade name, manufactured by Keyence Corporation) for electrophotography, in which the elastic roller for electrophotography is rotated about the central axis of the shaft core as the rotation axis. The outer diameters at two points 1 cm inside from the end of the elastic roller in the longitudinal direction and the end in contact with the first ring seal are measured. The difference between the two measured outer diameters was taken as the outer diameter difference in the longitudinal direction of the electrophotographic elastic roller, and was evaluated as follows.
A: All of the 500 electrophotographic elastic rollers formed have an outer diameter difference of less than 50 μm. B: Among the 500 electrophotographic elastic rollers formed, those having an outer diameter difference of 50 μm or more in the longitudinal direction. Within 2 C: Among the 500 electrophotographic elastic rollers formed, 3 or more having a difference in outer diameter of 50 μm or more in the longitudinal direction are shown in Table 1.

[Number of times the first ring seal is stuck to the lower support shaft]
The number of interruptions in the manufacturing cycle is that when the shaft core and the first ring seal coated with the paint are removed from the lower support shaft, the paint adhering to the lower surface of the first ring seal adheres to the lower support shaft. It was the number of times. From the number of times the first ring seal adhered to the lower support shaft, the following evaluation was made.
A: Out of 500 electrophotographic elastic rollers formed, the number of times the first ring seal adhered to the lower support shaft was 0. B: Out of 500 electrophotographic elastic rollers formed, the first ring seal was down. The number of times of sticking to the support shaft is 1 to 2 times. C: Among 500 electrophotographic elastic rollers, the number of times of attaching the first ring seal to the lower support shaft is 3 times or more and 10 times or less. D: Electrophotography Of the 500 elastic rollers for molding, the number of times that the first ring seal was stuck to the lower support shaft was 11 times or more.

[Example 2]
The diameter of the lower support shaft was 12.0 mm. A groove having a depth of 2.0 mm and a width of 3.0 mm is formed 2.0 mm below the upper surface of the lower support shaft, and an O-ring made of silicone rubber and having an inner diameter of 7.8 mm and an outer diameter of 13.0 mm is formed in the groove. Installed as a second ring seal. The diameter of the second ring seal when attached to the lower support shaft was 13.0 mm. An electrophotographic elastic roller was produced and evaluated in the same manner as in Example 1 except that the second ring seal was attached to the lower support shaft. The results are shown in Table 1.

Example 3
A tube for sending compressed air with the lower support shaft hollow was connected, and the second ring seal was attached at a position 10.0 mm below the upper surface of the lower support shaft. Further, an electrophotographic elastic roller was prepared and evaluated in the same manner as in Example 2 except that one hole having a diameter of 1.0 mm was formed 2.0 mm below the upper surface of the lower support shaft so that compressed air was emitted. . The results are shown in Table 1. The pressure of the compressed air is 0.2 MPa as a gauge pressure. When the upper surface of the lower support shaft enters the center hole of the coating head, injection starts and the first ring seal is pushed vertically upward of the coating head. I stopped when.

Example 4
An electrophotographic elastic roller was prepared and evaluated in the same manner as in Example 3 except that the pressure of the compressed air was changed to 0.5 MPa as a gauge pressure. The results are shown in Table 1.

Example 5
An electrophotographic elastic roller is produced in the same manner as in Example 2 except that a second ring seal having a diameter of 12.5 mm and a thickness of 1.0 mm is integrated with the lower support shaft 2.0 mm below the upper surface of the lower support shaft. And evaluated. The results are shown in Table 1.

[Comparative Example 1]
An electrophotographic elastic roller was produced and evaluated in the same manner as in Example 1 except that the diameter of the lower support shaft was 8.0 mm. The results are shown in Table 1.

Claims (3)

A method of manufacturing an elastic roller for electrophotography having a shaft body and a coating film on its outer peripheral surface,
(1) An annular slit is formed on the inner peripheral surface of the center hole outside the shaft core supported along the vertical direction by the upper support shaft and the lower support shaft having a diameter larger than the diameter of the shaft core. Arranging the coating head having a predetermined gap between the peripheral surface of the shaft core and the annular slit;
(2) inserting an annular first ring seal centered on a hole having an inner diameter smaller than the diameter of the lower support shaft into the center hole from above and positioning it directly below the annular slit;
(3) The upper surface of the first ring seal is adjusted so that the upper end of the coating film forming region of the shaft core is the same as the upper surface of the first ring seal or does not exceed the upper surface of the coating head. A step of being positioned so as to be higher than
(4) The paint is discharged from the annular slit onto the upper surface of the first ring seal, and the gap between the peripheral surface of the shaft core and the annular slit is filled with the paint, and the lower support shaft is moved vertically upward. And applying the paint on the peripheral surface of the shaft core by moving the shaft core upward with respect to the annular slit, and
(5) moving the lower support shaft further vertically upward to disengage the shaft core body coated with the paint and the first ring seal from the center hole;
A method of manufacturing an elastic roller for electrophotography, wherein the lower support shaft is moved vertically upward in step (5) without bringing the lower support shaft into contact with the lower surface of the first ring seal. The lower support shaft is located below the lower surface of the coating head in the step (3), and is inserted into the central hole by moving the lower support shaft vertically upward in the step (4) or (5). A second ring seal at a position such that
The lower support shaft in the step (4) or (5) is moved vertically upward to insert the second ring seal into the center hole, the second ring seal, the center hole inner wall, and the first A closed space is formed with the ring seal, and the first ring seal is moved above the central hole by using the pressure of the closed space, thereby causing the lower support shaft in the step (5) to move vertically upward. The method for manufacturing an elastic roller for electrophotography according to claim 1, wherein the movement is performed without bringing the lower support shaft and the lower surface of the first ring seal into contact with each other. The lower support shaft has injection means for injecting compressed gas to a position vertically above the second ring seal;
In the step of moving the first ring seal in the step (5) above the center hole by using the pressure of the closed space, the compressed gas is injected from the injection means, whereby the step (5) The method for producing an elastic roller for electrophotography according to claim 2, wherein the lower support shaft is moved vertically upward without contacting the lower support shaft and the lower surface of the first ring seal.

Images