JP2012098328A - Method for manufacturing conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating head for reducing resistance irregularity of a conductive rubber layer that is formed by uniformly applying liquid conductive rubber material including conductive particles, around a shaft core body, in a ring coating.SOLUTION: In the coating head for use in the ring coating, the cross sectional area of the flow passage satisfies a prescribed requirement while holding a flow passage width constant in the coating head, such that the generation of aggregates of conductive particles is reduced, residual stress of the liquid conductive rubber material provided across an annular flow passage is mitigated, and a function of a substantial liquid restriction effect for attaining the uniform flow in the circumferential direction is achieved at a higher order.

Description

  The present invention relates to an electrophotographic image forming apparatus such as a printer and a copying machine, and a method for manufacturing a conductive roller used in an electrophotographic process cartridge.

  In the contact developing type electrophotographic apparatus, the developing roller and the photosensitive member, and the developing roller and the toner regulating member are in pressure contact with each other with toner interposed therebetween. The toner that is not developed on the photoreceptor is peeled off by the toner application roller, stirred in the container, and conveyed again onto the development roller by the toner application roller. As a result of repeating these steps, the toner is subjected to great stress. Therefore, for the purpose of reducing the stress on the toner, a developing roller having a configuration in which a conductive rubber layer is provided around the shaft core body is often used. Furthermore, there is also a conductive roller having a configuration in which a surface layer is provided by applying various resin solutions in order to impart surface properties to the outer peripheral side of the conductive rubber layer as required. In addition, if the developing roller cannot maintain a stable contact state with the photosensitive member, the amount of toner development varies, the pressure distribution on the photosensitive member varies, and the image is adversely affected. Is needed. In addition, a charging roller for bringing the photosensitive member into uniform contact with the photosensitive member also requires high dimensional accuracy because it is necessary to uniformly charge the photosensitive member.

  As a method for manufacturing a highly accurate conductive roller, a manufacturing method using a cylindrical coating head is disclosed (see Patent Document 1). According to this, the conductive rubber layer having a uniform thickness can be formed by directly coating the liquid conductive rubber material on the outer periphery of the shaft core body with a simpler apparatus.

  In general, when a conductive roller is manufactured using a manufacturing method such as that disclosed in Patent Document 1, it is necessary to make the flow rate of the material discharged from the discharge port of the coating head uniform in the circumferential direction. For this purpose, a coating head having a liquid throttle channel for applying a force flowing in the circumferential direction to the material is used. According to this, the flow rate of the material flowing in the coating head becomes uniform in the circumferential direction, and then the flow rate of the discharged material becomes uniform in the circumferential direction by proceeding to the discharge port.

  However, in the liquid constriction flow path, a strong shearing force is applied to the material, so that the aggregation state of the conductive particles is likely to change. When the aggregation state of the conductive particles changes, the resistance becomes uneven in the circumferential direction and the axial direction of the conductive roller. This causes image density unevenness. Therefore, it is not preferable to use a liquid throttle channel. Patent Document 2 discloses a method of improving the material flow in the coating head and shortening the time during which a strong shear force is applied. However, even if the time during which a strong shear force is applied is shortened, a strong shear force is applied to the material, which also changes the agglomerated state of the conductive particles.

JP 2007-130589 A JP 2006-106571 A

  In the manufacturing method using the coating head having the liquid constriction flow path, the flow rate of the discharged material is uniformly uniform in the circumferential direction, so that the conductive material having a uniform thickness is formed around the cylindrical shaft core. A conductive roller having a conductive rubber layer can be manufactured.

  However, when the conductive roller manufactured by the above manufacturing method is incorporated as a developing roller in a contact developing type electrophotographic apparatus, a good quality image can be obtained without any problem in a normal environment, but in a low temperature and low humidity environment. After the endurance test, the amount of toner supplied to the photoreceptor became non-uniform, resulting in uneven image density. Even when the electrophotographic apparatus was incorporated as a charging roller, it was difficult to uniformly charge the photoconductor after performing a durability test in a low temperature and low humidity environment, resulting in uneven image density.

  Therefore, as a result of conducting a detailed investigation of the conductive roller in which the density unevenness occurred, agglomerates of carbon black, which is conductive particles, are non-uniformly present in the conductive roller, thereby causing uneven resistance in the conductive roller. I found out that it was occurring. In a low-temperature and low-humidity environment, since the amount of moisture in the atmosphere is small, the environment is easily charged, and resistance unevenness becomes more prominent.

  The reason why such resistance unevenness occurs is considered as follows. That is, since the liquid throttle channel is a portion where the channel width is abruptly narrowed, the flow direction and speed of the liquid conductive rubber material passing through the liquid throttle channel changes. As a result, carbon blacks, which are conductive particles contained in the liquid conductive rubber material, collide with each other, and carbon black aggregates are easily generated. When the liquid conductive rubber material passes through the most narrowed portion, a strong shear force is applied to the liquid conductive rubber material because the flow path width is narrow. Therefore, the aggregate state of carbon black that has become an aggregate changes. Further, after passing through the liquid throttle channel, the channel width is widened because it is necessary to relieve the residual stress applied to the liquid conductive rubber material. A turbulent flow in which the direction and speed of the material flow are irregularly changed again at a portion where the flow path width is wide. For this reason, the ratio of carbon black aggregates to be discharged becomes minute unevenness in the circumferential direction and the longitudinal direction of the conductive roller. When it becomes a conductive roller, it is considered that minute unevenness of the aggregate of carbon black becomes unevenness of image density in a low temperature and low humidity environment.

  An object of the present invention is to provide a conductive roller capable of obtaining a high-quality image even after an endurance test performed in a low-temperature and low-humidity environment as described above.

  The present invention provides one supply port for supplying a liquid conductive rubber material containing conductive particles from the outside, a distribution chamber for annularly distributing the liquid conductive rubber material, and the liquid conductive rubber A conductive rubber layer is formed around the cylindrical shaft core using an annular coating head having an annular discharge port for discharging the material to the inner peripheral surface and an annular flow path extending from the distribution chamber to the discharge port. The width of the annular channel is constant, and the sectional area of the annular channel is (the inlet sectional area of the annular channel: Sa)> (the discharge port Cross-sectional area: Sb), and (maximum cross-sectional area in the annular channel: Sc)> (Sa + Sb), and (maximum break in the annular channel from the inlet of the annular channel) The flow path length to the area part: La) is 50% or more of the total flow path length from the inlet part to the discharge port (L). The method for producing a conductive roller according to claim.

  According to the method for manufacturing a conductive roller according to the present invention, it is possible to reduce the generation of aggregates of conductive particles, thereby preventing the occurrence of image density unevenness due to resistance unevenness. In the present invention, the flow rate of the liquid conductive rubber material discharged from the discharge port is uniform in the circumferential direction, and the residual stress applied to the liquid conductive rubber material can be reduced. Thereby, the deterioration of the shape of the conductive roller can be prevented, and the occurrence of image defects due to the shape can be prevented.

It is a schematic diagram which shows the example of the coating apparatus which can be used for this invention. It is sectional drawing which shows the example of the coating head which has a liquid throttle flow path. It is sectional drawing which shows the example of the coating head which concerns on this invention. It is sectional drawing explaining the flow path length and cross-sectional area of the annular flow path of the coating head which concerns on this invention. It is sectional drawing which shows the example of the coating head which can be used for this invention. It is sectional drawing which shows the example of the coating head which cannot fully acquire the effect which concerns on this invention. It is sectional drawing which shows the electroconductive roller which concerns on this invention. 1 is a schematic cross-sectional view for explaining an example of an image forming apparatus according to the present invention. It is the schematic of the apparatus which measures the resistance of the electroconductive roller which concerns on this invention. It is a schematic diagram for demonstrating the location which measures the shape precision of the electroconductive roller which concerns on this invention.

  Hereinafter, although the form for implementing this invention is demonstrated, this invention is not limited by this.

  A schematic diagram of a conductive roller manufacturing apparatus (hereinafter referred to as a ring coater) having an annular coating head (hereinafter referred to as a coating head) that can be suitably used in the method for manufacturing a conductive roller of the present invention is shown in FIG. .

  In this ring coating machine, a coating head side column 32 is mounted substantially vertically on a coating head side frame 31, and a coating head side precision ball screw is provided above the coating head side frame 31 and the coating head side column 32. 33 is attached substantially vertically. Two coating head side precision ball screws 33 and two coating head side guides 43 are attached to the coating head side column 32 so as to be parallel to each other. The coating head side stage 34 connects the coating head side guide 43 and the coating head side precision ball screw 33, and a rotary motion is transmitted from the servo motor 35 via the pulley 36 so that it can be moved up and down. A coating head fixing table 44 is attached to the coating head side column 32. A coating head 38 is attached to the coating head fixing table 44.

  A shaft core holding shaft bracket 37 is attached to the coating head side stage 34. A shaft core lower holding shaft 39 that holds and fixes the shaft core body 102 is attached to the shaft core body holding shaft bracket 37 substantially vertically. Further, the central axis of the shaft core body holding shaft 40 that holds the shaft core body 102 of the roller on the opposite side is attached to the upper part of the shaft core body holding shaft bracket 37, and the shaft core body holding shaft 40 is below the shaft core body. The shaft core body 102 is held by being arranged so as to be substantially concentric facing the holding shaft 39.

  The center of the coating head 38, the center of the shaft core lower holding shaft 39, and the center of the shaft core upper holding shaft 40 are arranged in a straight line in the axial direction.

  The liquid conductive rubber material supply port 41 is connected to a cylinder 53 via a first pipe 42 for transporting the liquid conductive rubber material. The cylinder 53 is mounted on the cylinder side mount 45, and the cylinder side column 46 is mounted on the cylinder side mount 45 substantially vertically. A cylinder-side precision ball screw 47 is mounted substantially vertically on the cylinder-side mount 45 and the cylinder-side column 46, and two cylinder-side guides 51 are attached to the cylinder-side column 46 in parallel with the cylinder-side precision ball screw 47. ing. A cylinder-side stage 48 is attached in connection with a precision ball screw so that a rotary motion is transmitted from a servo motor 35 via a pulley 36 so that the cylinder-side stage 48 can move up and down. The cylinder side stage 48 is provided with a piston bracket 49, and the bracket is provided with a piston 54. The outer periphery of the piston is arranged in close contact with the inner surface of the cylinder 53 so as to be able to reciprocate.

  The cylinder 53 is connected to a material supply pump (hereinafter, pump not shown) via the second pipe 50. The pump includes a mixing mixer, a material dispensing device, a material tank, and the like, and is capable of dispensing a fixed amount (a constant amount per unit time) of the liquid conductive rubber material. A certain amount of the liquid conductive rubber material is weighed from the material tank by the material dispensing device and mixed by the mixing mixer. Thereafter, the liquid conductive rubber material mixed by the material supply pump is sent to the cylinder 53 via the second pipe 50. The liquid conductive rubber material filled in the cylinder 53 is pushed out by the lowering of the piston 54 and sent to the supply port 41 via the first pipe 42.

  A series of flows from when the liquid conductive rubber material is fed to the supply port 41 until it is discharged from the discharge port of the coating head 38 will be described with reference to FIG. The coating head 38 is configured by a hollow cylindrical outer ring 61 having a hollow cylindrical inner ring 60 and one supply port 41 holding a hollow cylindrical cap ring 62. The inner ring 60 and the outer ring 61 are coaxially combined, and the outer ring 61 holds the cap ring 62, and the inner ring 60 and the outer ring 61 are used to circularly distribute the liquid conductive rubber material. A circumferential groove-shaped distribution chamber 63 is provided. The distribution chamber 63 is a place where the liquid conductive rubber material flows in the circumferential direction by increasing the liquid pressure by a desired pressure by the annular flow path 64 and the liquid throttle flow path 69 described below.

  The inner ring 60 and the outer ring 61 are coaxially combined, and the cap ring 62 is held by the outer ring 61, whereby the annular flow path 64 is configured. The channel width 65 of the annular channel is usually set to 0.1 mm to 5.0 mm, more preferably 0.5 mm to 2.0 mm. The annular flow path 64 and the distribution chamber 63 communicate with each other, and a portion having a circumferential groove shape in the circumferential direction is defined as the distribution chamber 63, and the other portions are defined as the annular flow path 64.

  The liquid conductive rubber material fed from the supply port 41 is distributed in a ring shape in the distribution chamber 63 in the coating head 38, passes through the annular flow path 64 provided continuously to the distribution chamber 63, and enters the inside of the coating head 38. It discharges from the cyclic | annular discharge outlet provided in the surrounding surface.

  In order to make the liquid conductive rubber material applied to the shaft core 102 constant, the discharge amount from the coating head and the supply amount from the cylinder 53 are made constant. As a result, the shaft core 102 moves upward in the axial direction relative to the coating head 38, and a cylindrical (roller-shaped) conductive material made of a liquid conductive rubber material on the outer periphery of the shaft core 102. A rubber layer 101 is formed.

  The coating head 38 shown in FIG. 2, which is a conventional technique, has a configuration including a liquid throttle channel 69 in which the channel width 65 of the annular channel is abruptly narrowed. The role of the liquid throttle channel 69 is that the flow rate of the liquid conductive rubber material discharged from the discharge port becomes uniform in the circumferential direction. That is, the liquid constriction channel 69 makes it difficult for the liquid conductive rubber material to travel in the direction of the discharge port, and wraps around in the circumferential direction. Thereafter, by proceeding in the direction of the discharge port, the flow rate of the liquid conductive rubber material discharged from the annular discharge port becomes uniform in the circumferential direction.

  In the liquid throttle channel 69, since the direction and speed of the liquid conductive rubber material flowing in the narrow channel changes, adjacent carbon blacks collide with each other, and aggregates are easily generated. When passing through the liquid throttle channel 69, the aggregation state of the carbon black changes due to a strong shearing force, and passes through the liquid throttle channel 69 in that state. Thereafter, the direction and speed of the material flow become irregular turbulent flow where the flow path width becomes wide. Therefore, when the discharged liquid conductive rubber material becomes the conductive rubber layer 101, the presence state of the carbon black aggregate becomes minute unevenness in the circumferential direction and the longitudinal direction. When the conductive roller 104 is measured in a low-temperature and low-humidity environment, the value of the current flowing through the conductive roller differs between the location where the carbon black agglomerates exist and the location where the carbon black aggregate does not exist because of the dry environment. The resistance of the entire property roller 104 was uneven.

  In the present invention, in order to solve the above problems, the formation of carbon black aggregates is reduced. Furthermore, in addition to the reduction in the formation of carbon black agglomerates, the flow rate of the liquid conductive rubber material is uniformly discharged from the discharge port in the circumferential direction. In addition, the stress applied to the liquid conductive rubber material from the ring coater to the coating head 38 becomes a residual stress, so that the shape of the conductive roller after discharge is not deteriorated at a high level. It is.

  Below, the coating head 38 concerning this invention is demonstrated in detail using FIG.3 and FIG.4.

  3 is the same as that of the coating head 38 according to the present invention shown in FIG. 3 and the conventional coating head 38 described with reference to FIG. Explained.

  As shown in FIG. 4, the channel width 65 of the annular channel 64 is always kept constant. If the cut surface of the annular flow path 64 formed when the liquid conductive rubber material flowing through the annular flow path 64 is cut by a plane perpendicular to the direction toward the discharge port, the cross-sectional area of the annular flow path 64 is distributed. A straight line connecting points a and b in FIG. 4, which is a contact point between the chamber 63 and the annular flow path, is drawn. An area of a surface (A surface) obtained when the line segment ab is rotated around the central axis of the coating head 38 is defined as an inlet cross-sectional area (Sa) 66. A straight line connecting points c and d in FIG. The area of the surface (B surface) obtained when the line segment cd is rotated around the central axis of the coating head 38 is defined as a discharge port cross-sectional area (Sb) 67.

  By making the discharge port cross-sectional area (Sb) 67 smaller than the inlet cross-sectional area (Sa) 66 of the annular flow path, the pressure applied to the liquid conductive rubber material passing through the annular flow path increases as it approaches the discharge port. Therefore, it becomes difficult to proceed to the discharge port. Therefore, it becomes easy to go around in the circumferential direction, and can play a role of a substantial liquid squeezing effect.

  Further, a point at a position farthest from the central axis of the coating head 38 in the wall surface of the annular flow path 64 is defined as point e. At this point e, a straight line perpendicular to the surface with which the outer wall surface of the annular channel 64 contacts is drawn from the point e toward the inner wall surface of the annular channel 64. A point where the straight line intersects the inner wall surface of the annular flow path 64 is defined as f point. The area of the surface obtained when the line ef connecting the points e and f is rotated around the central axis of the coating head is defined as the maximum cross-sectional area (Sc) 68. By making the maximum sectional area (Sc) 68 larger than the sum of the inlet sectional area (Sa) 66 and the outlet sectional area (Sb) 67, the residual stress of the liquid conductive rubber material can be sufficiently relaxed. Therefore, the formed conductive rubber layer 101 can be prevented from being deformed by residual stress. At this time, the length of the line segment where the line passing through the center of the width of the annular flow path 64 is cut off at the A plane and the B plane is defined as the total flow path length (L). The flow path length (La) 70 from the cross section of the inlet cross sectional area (Sa) 66 to the cross section of the maximum cross sectional area (Sc) 68 is changed from the cross section of the inlet cross sectional area (Sa) 66 to the cross section of the discharge port cross sectional area (Sb) 67. By setting it to 50% or more of the total flow path length (L) 71, it is possible to secure a sufficient time for the residual stress to relax and to prevent the deformation of the conductive rubber layer 101 due to the residual stress. .

  The conductive rubber layer 101 formed on the outer peripheral surface of the shaft core body 102 is crosslinked and cured to form the conductive rubber layer 101. At this time, since the uncured conductive rubber layer 101 having a cylindrical shape (roller shape) has adhesiveness, it is preferable to perform the heat treatment by a non-contact heat treatment method.

  Examples of the heat treatment method include an infrared heating method, a hot air heating method, and a nichrome heat heating method. In particular, infrared heating is preferable because the apparatus is simple and the layer of the uncured product can be uniformly heat-treated in the longitudinal direction. At this time, heat treatment can be uniformly performed in the circumferential direction by fixing the infrared heating device and rotating the shaft core body 102 provided with the cylindrical (roller-shaped) uncured material layer in the circumferential direction.

  The heat treatment temperature on the surface of the conductive rubber layer is preferably 100 to 250 ° C. at which the curing reaction starts although it depends on the material used. For example, in the case of performing infrared heating, the distance between the infrared heating device and the uncured conductive rubber layer 101, the output, and the like may be adjusted according to the characteristics of the material (thermal conductivity, specific heat). Moreover, what is necessary is just to adjust the temperature and direction of a hot air when performing hot air heating.

  Here, for the purpose of stabilizing physical properties after curing of the conductive rubber layer 101, removing reaction residues and unreacted low molecular components in the conductive rubber layer 101, etc., the conductive rubber layer 101 is cured and formed. Further, secondary curing that performs heat treatment or the like may be performed.

  The conductive roller obtained in the present invention can be used as a developing roller used in an electrophotographic image forming apparatus.

  In the developing roller and the charging roller, the thickness of the conductive rubber layer 101 obtained by curing the conductive rubber layer 101 is preferably in the range of 0.5 mm to 10.0 mm. More preferably, it is 1.0 mm or more and 6.0 mm or less. This is because the developing roller rotates while being in contact with other members, and it is necessary to keep the contact state (in the nip) stable. If the thickness of the conductive rubber layer 101 is less than 0.5 mm, for example, in the case of a developing roller, the elasticity of the conductive rubber layer 101 cannot be obtained and the toner deteriorates due to stress and the image becomes bulky. It becomes a thing. Further, when the liquid conductive rubber material is applied so that the layer thickness of the conductive rubber layer 101 exceeds 10.0 mm, the liquid conductive rubber material droops in the direction of gravity due to its own weight, and has an excellent outer diameter. It is difficult to realize dimensions and runout.

  As the shaft core body 102 of the conductive roller according to the present invention, any material can be used as long as it is conductive, and it can be appropriately selected from carbon steel, alloy steel, cast iron, and conductive resin. .

  Here, examples of the alloy steel include stainless steel, nickel chromium steel, nickel chromium molybdenum steel, chromium steel, chromium molybdenum steel, nitriding steel to which Al, Cr, Mo and V are added.

  From the viewpoint of strength, a metal one is preferable. Furthermore, as a rust prevention measure, the shaft core body 102 material can be plated and oxidized. As the type of plating, both electroplating and electroless plating can be used.

  From the viewpoint of dimensional stability of plating thickness accuracy, electroless plating is preferable. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, Kanigen plating, and other various alloy plating. Examples of the nickel plating include Ni-B, Ni-WP, and Ni-P-PTFE composite plating. Each film thickness is preferably 0.05 μm or more, more preferably 0.1 to 30 μm.

  The conductive roller according to the present invention can be used as a developing roller used in an image forming apparatus and an electrophotographic process cartridge. An example of the schematic is shown in FIG. FIG. 7A shows a cross section parallel to the longitudinal direction of the developing roller, and FIG. 7B shows a cross section perpendicular to the longitudinal direction.

  In the electrophotographic process cartridge, the developing roller is always in pressure contact with the developing blade 8 and the toner 5. For this reason, in order to reduce the damage given to these members, it is important to obtain a good image by using a material having a low hardness and a small compression set. The conductive rubber layer 101 does not have to be a single layer, and may be a multilayer. In the present invention, a layer on the shaft core body 102 is formed, but a new conductive rubber layer can be formed on the conductive rubber layer 101 that has already been formed.

  The liquid conductive rubber material used in the present invention comprises a mixture of a liquid rubber composition and conductive particles. Examples of the liquid conductive rubber material used for the conductive rubber layer 101 include liquid diene rubber (butadiene rubber, isoprene rubber, nitrile rubber, chloroprene rubber, ethylene propylene rubber), liquid silicone rubber, and liquid urethane rubber. These materials can be used alone or in combination. Further, a foam of these materials may be used for the conductive rubber layer 101. Among these, since it is important for the conductive rubber layer 101 to have a moderately low hardness and sufficient deformation recovery force, liquid silicone rubber or liquid urethane rubber is used as the material used for the conductive rubber layer 101. It is preferable. In particular, it is more preferable to use an addition reaction cross-linkable liquid silicone rubber because it has excellent workability, high stability of dimensional accuracy, and excellent productivity such that no reaction by-product is generated during the curing reaction.

  The addition-type liquid silicone rubber is cured by an addition reaction between an alkenyl group-containing polysiloxane and a hydrosilyl group-containing hydrogen polysiloxane 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 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 that 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, if it exceeds 3.0 times, excessively unstable hydrosilyl groups remain, which is not preferable because the hardness and current of the conductive roller may change over time.

  As the catalyst for the addition-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.

  Furthermore, according to the specific use of the conductive roller, a conductive agent or a non-conductive filler can be appropriately blended as a component necessary for the function required for the conductive rubber layer itself.

Conductive agents added for the purpose of imparting conductivity to the conductive rubber layer include carbon black, graphite, aluminum, palladium, silver, iron, copper, tin, various conductive metals or alloys of stainless steel, tin oxide, oxidation Zinc, indium oxide, titanium oxide, antimony oxide, molybdenum oxide, tin oxide-antimony oxide solid solution, various conductive metal oxides of tin oxide-indium oxide solid solution, insulating materials coated with these conductive materials, etc. Examples thereof include powder. Further, LiClO ₄ or NaClO ₄ perchlorate or quaternary ammonium salt may be used as the ion conductive agent. Among these, carbon black can be suitably used because it is relatively easily available.

  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.

  Further, in order to improve the wear resistance of the conductive roller used in the present invention, a surface layer 103 may be formed on the outer periphery of the conductive rubber layer 101. Similarly to the conductive rubber layer 101, the surface layer 103 does not have to be a single layer, and may be a multilayer.

  Examples of the material for forming the surface layer 103 include various polyamides, fluororesins, hydrogenated styrene-butylene resins, urethane resins, silicone resins, polyester resins, phenol resins, imide resins, and olefin resins.

  In the surface layer 103, fine particles having a volume average particle diameter of 1 to 20 μm can be dispersed according to individual applications. Examples of such fine particles include polymethyl methyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles.

  The surface layer 103 can contain a conductive agent in order to adjust the electrical resistance of the entire conductive 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 the surface layer 103 is dispersed using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a ball mill. The obtained dispersion for forming the surface layer is applied to the surface of the conductive rubber layer 101 by a spray coating method, a dipping method, or the like.

  When the conductive roller of the present invention is used as a developing roller, the developing roller carries toner (toner) in a state of being in contact with or pressed against a photosensitive member as a latent image carrier that carries a latent image. . The developing roller has a function of visualizing the latent image as a toner image by applying toner as toner to the photoreceptor.

  FIG. 8 shows an example of a general electrophotographic process cartridge and an image forming apparatus in which the conductive roller of the present invention is mounted as a developing roller.

  The image forming apparatus shown in FIG. 8 has one image forming unit 10a to 10d for forming yellow, cyan, magenta, and black images, respectively, and is provided in a tandem system. In addition, the photoconductor 11, the charging device 12, the developing device 14, and the cleaning device 15 are integrated to form a process cartridge. The process cartridge according to the present invention includes a developing cartridge type including the developing device 14.

  The developing device 14 includes a developing container 6 that contains the one-component toner 5 and a developing roller 1 that is located in an opening extending in the longitudinal direction in the developing container 6 and that is opposed to the photoconductor 11. The electrostatic latent image on the photoconductor 11 is developed and visualized. Further, a toner supply roller 7 having a function of supplying the one-component toner 5 to the developing roller 1 and a function of scraping off the one-component toner 5 remaining on the developing roller 1 without being developed is provided. Further, a developing blade 8 having a function of regulating the carrying amount of the one-component toner 5 on the developing roller 1 and a function of friction charging is provided.

  The surface of the photoreceptor 11 is uniformly charged to a predetermined polarity and potential by the charging device 12, and image information is irradiated as a beam from the additional exposure device 13 to the surface of the photoreceptor 11 to form an electrostatic latent image. . Next, one-component toner is supplied to the formed electrostatic latent image from a developing device 14 using the conductive roller of the present invention as the developing roller 1, and the toner image is developed on the surface of the photoreceptor 11. This toner image is transferred to the recording material 25 when it comes to a location facing the image transfer device 16.

  In FIG. 8, four image forming units 10 a to 10 d are interlocked to form a predetermined color image on the transfer material 25. The transfer / conveying belt 17 is wound around a driving roller 18, a tension roller 19 and a driven roller 20. The transfer material 25 is conveyed to the transfer conveyance belt 17 in a form that is electrostatically adsorbed by the action of the adsorption roller 21. Reference numeral 22 denotes a supply roller for supplying the transfer material 25.

  The transfer material 25 on which the image has been formed is peeled off from the transfer conveyance belt 17 by the action of the peeling device 23 and sent to the fixing device 24, and the toner image is fixed on the transfer material 25 to complete the printing. On the other hand, the photoconductor 11 after the transfer of the toner image to the transfer material 25 is further rotated, the surface is cleaned by the cleaning device 15, and is neutralized by a neutralization device (not shown) if necessary. Thereafter, the photoreceptor 11 is used for the next image formation.

  The conductive roller of the present invention is not only the developing roller described above, but also has a uniform uniformity of the conductive rubber layer 101. Therefore, the charging roller, transfer roller, driving roller 18, fixing roller 28, pressure roller It can also be used for applications requiring electrical conductivity such as 29.

[Example 1]
In manufacturing the conductive roller, the shaft core 102 is nickel-plated on a round rod-shaped shaft core 102 (free-cutting steel SUM24L) having an outer diameter of 6 mm, and further a primer (trade name: DY39-051 Toray) having a thickness of about 1 μm. After application of Dow Corning), it was baked at 150 ° C. for 30 minutes.

  Thereafter, a base material having the following composition was prepared.

Dimethylpolysiloxane (weight average molecular weight 34000): 100 parts by mass;
Carbon black (Raven 890 manufactured by Columbian Chemical): 10 parts by mass;
To 100 parts by mass of this base material, 1 part by mass of a complex of chloroplatinic acid and divinyltetramethyldisiloxane was added as a curing catalyst. Further, a liquid comprising an addition-type liquid silicone rubber, in which methylhydrogenpolysiloxane in an amount of 1.2 mol of hydrosilyl group is added to 1 mol of vinyl group contained in dimethylpolysiloxane substituted with the vinyl group. Obtained material.

For the production of the conductive roller, a vertical ring coater having a coating head of the form shown in FIG. 1 was used. The inner diameter of the cap ring 62 used in the coating head shown in FIG. 3 is 11.5 mm, the channel width of the annular channel is 1.0 mm, and the inlet cross-sectional area of the annular channel (Sa) Is 65.9 mm ² , the cross-sectional area (Sb) of the discharge port is 36.1 mm ² , which is about half the size of Sa, and the maximum cross-sectional area (Sc) of the annular flow path is 160.2 mm ² (Sa + Sb ) Was set to a value sufficiently larger than. The channel length (La) of the annular channel was 24 mm, and 60% of the total channel length (L) of 40 mm of the annular channel.

  The cylinder is preliminarily filled with the above liquid conductive rubber material, and the shaft core lower holding shaft 39 is vertically moved at 60 mm / s to move the shaft core 102 and at the same time, the piston 56 is moved to 15 mm / The liquid conductive rubber material filled in the cylinder was discharged by lowering at s, and an uncured conductive rubber layer 101 having a coating layer of the liquid conductive rubber material on the outer periphery of the shaft core 102 was manufactured.

  The produced uncured conductive rubber layer 101 is rotated at 60 rpm around the shaft core body 102, and an infrared heating lamp (trade name: HYL25, manufactured by Highbeck Co., Ltd.) is used for infrared irradiation on the surface of the uncured molded layer. (Output 1000W) was irradiated for 4 minutes to be cured. Note that the distance between the surface of the molded product layer and the lamp during infrared irradiation was 60 mm, and the temperature of the molded product layer surface was 200 ° C.

Thereafter, the physical properties of the conductive rubber layer 101 of the cured silicone rubber are stabilized, and the reaction residue and unreacted low molecular components of the conductive rubber layer 101 of the silicone rubber are removed in an electric furnace at 200 ° C., 4 ° C. Secondary curing for hours was performed. In this way, a conductive roller having a conductive rubber layer having a layer thickness of 3.0 mm on the outer periphery of the shaft core body 102 was obtained. Thereafter, both ends of the obtained conductive roller were cut by 15 mm. Next, resistance unevenness and shape accuracy of the manufactured conductive roller were measured. The method for measuring the resistance unevenness of the conductive roller will be described in detail with reference to FIG. In an environment of room temperature 5 ° C. and humidity 30%, both ends of the shaft core body 102 of the conductive roller 104 are received by V blocks (not shown), and the conductive roller is kept horizontal. The outer circumference of a metal disk having a thickness of 2 mm and a diameter of 20 mm is pressed against the outer circumferential surface of the conductive roller while applying a load of 4.9 N, and a voltage of 50 V is applied to the conductive roller and 60 mm in the longitudinal direction of the conductive roller. It was moved at a speed of / s. The voltage value in the longitudinal direction applied to the resistance of 10 kΩ connected in series with the V block receiving the end of the shaft core was measured intermittently at 0.1 second intervals. The current value flowing through each part of the conductive roller and the resistance value of the conductive roller were calculated from the series of voltage values obtained. The maximum resistance value (R _A1 ) and the minimum resistance value (R _B1 ) were obtained.

Thereafter, the conductive roller was rotated by 30 °, and the same measurement was repeated until the conductive roller rotated once. From the maximum resistance value (R _Ai (i = 1 to 12)) and the minimum resistance value (R _Bi (i = 1 to 12)) in each phase, each arithmetic mean value (Ra =

And Rb =

), And the ratio of Ra to Rb (Ra / Rb) is defined as Rb) resistance unevenness of the conductive roller, and evaluation is performed according to the following criteria. Table 1 shows the results.

A: When resistance unevenness is less than 2.0 B: When resistance unevenness is 2.0 or more and less than 4.0 C: When resistance unevenness is 4.0 or more.

  In order to evaluate the shape accuracy of the conductive roller, the outer diameter difference of the conductive roller was measured. A non-contact laser length measuring device (rotating the conductive roller around the central axis of the shaft core as the rotation axis, and the difference between the maximum outer diameter and the minimum outer diameter of the conductive roller. The outer diameter difference was measured with a product name: LS-5000 (manufactured by Keyence). The maximum outer diameter and the minimum outer diameter here are the maximum value and the minimum value of the outer diameter at 360 points measured by rotating the conductive roller by 1 °, respectively. As shown in FIG. 10, the outer diameter difference is obtained at three locations 1101, 1102, and 1103 that equally divide the conductive rubber layer 101 in the longitudinal direction of the conductive roller into four, and the average value from the obtained three data is obtained. The results are shown in Table 1.

A: When the outer diameter difference is less than 3% B: When the outer diameter difference is 3% or more and 5% or less C: When the outer diameter difference exceeds 5%.

  Then, the surface layer was provided in this electroconductive roller using the coating material of the following mixing | blending. The coating composition for the surface layer is shown.

Polyurethane polyol prepolymer (trade name: Takelac TE5060, manufactured by Mitsui Takeda Chemical Co.): 100 parts by mass;
・ Isocyanate (trade name: Coronate 2521, manufactured by Nippon Polyurethane Co., Ltd.): 77 parts by mass;
Carbon black (trade name: MA100, manufactured by Mitsubishi Chemical Corporation): 24 parts by mass;
-Methyl ethyl ketone (MEK): 180 parts by mass;
・ Roughness control fine particles (trade name: Art Pearl C400, manufactured by Negami Kogyo): 20% by mass with respect to resin component
These were dispersed with a horizontal disperser (trade name: NVM-03, manufactured by IMEX) for 1 hour under conditions of a peripheral speed of 7 m / s, a flow rate of 1 cc / min, and a dispersion temperature of 15 ° C.

  After dispersion, MEK was further added so that the solid content was 25% by mass and the film thickness was adjusted to 20 μm.

  Next, this paint was put into a cylinder having a diameter of 32 mm and circulated at a liquid flow rate of 250 cc / min and a liquid temperature of 23 ° C. Thereafter, the conductive roller was immersed in the cylinder at an intrusion speed of 100 mm / s and stopped for 10 seconds.

  Thereafter, the film was pulled up under conditions of an initial speed of 400 mm / s and an final speed of 200 mm / s and naturally dried for 10 minutes. Next, the raw material for the surface layer was cured by heat treatment at a temperature of 140 ° C. for 60 minutes to obtain a conductive roller with a surface layer. The surface roughness of the produced conductive roller with a surface layer was measured using a contact-type surface roughness meter (trade name: Surfcorder SE3500, manufactured by Kosaka Laboratory). The measurement conditions were a stylus with a radius of 2 μm, a pressing pressure of 0.7 mN, a measurement speed of 0.3 mm / s, a measurement magnification of 5000 times, a cutoff wavelength of 0.8 mm, and a measurement length of 2.5 mm. A total of 9 points in the circumferential direction and 3 points in the longitudinal direction were measured, and the average roughness of these measured values was defined as the surface roughness of the conductive roller. Here, the surface roughness in the present invention is a ten-point average roughness Rzjis, and indicates a value based on JISB0601-2001. As a result of the measurement, the ten-point average roughness Rzjis was 8.21 μm. A conductive roller with a surface layer was incorporated into an electrophotographic process cartridge as a developing roller. Here, the electrophotographic process cartridge incorporating the developing roller was left for 24 hours in an environment of room temperature 5 ° C. and humidity 30%.

  Next, the image evaluation method performed in the present embodiment will be described.

  The developed developing roller was assembled in an electrophotographic process cartridge (trade name: toner cartridge 316 black, manufactured by Canon Inc.).

  Next, this electrophotographic process cartridge was incorporated into an electrophotographic image forming apparatus (trade name: LBP5050, manufactured by Canon Inc., printing resolution: 600 dpi). Then, using this image forming apparatus, an intermittent durability test was performed in an environment of a room temperature of 5 ° C. and a humidity of 30%. When passing paper, perform full-color print operation in intermittent mode in which a character image with a printing rate of 2% is output on a genuine A4 paper (product name: Select Paper SC-250, manufactured by Canon Inc.) every 20 seconds. 2300 images were output. Thereafter, the developing roller was removed and incorporated in a new image forming apparatus of the same type, and 2300 images were output in the same manner. This durability test was repeated a total of 5 times.

  All black image samples were output at the end of a total of five durability tests. The density of the output sample for evaluation was measured with a color reflection densitometer (trade name: X-RITE 404A, manufactured by X-Rite Co.) at nine locations on the paper surface. The ratio between the maximum value and the minimum value at 9 locations (maximum value / minimum value) was used as the image density ratio of the conductive roller, and evaluation was performed according to the following criteria. The results are shown in Table 1.

A: When the image density ratio is less than 1.20 B: When the image density ratio is 1.20 or more and 1.30 or less C: When the image density ratio exceeds 1.30

  In addition, image evaluation due to the shape of the conductive roller was also performed. Evaluation is performed according to the following criteria, and the results are shown in Table 1.

A: When visually good B: Image unevenness due to the shape of the conductive roller is slightly confirmed, but there is no practical problem C: Image unevenness due to the shape of the conductive roller is confirmed.

[Example 2]
As shown in FIG. 5A, the same conditions as in Example 1 except that the channel length (La) of the annular channel is set to 20 mm, which is 50% of the total channel length (L) of the annular channel. A conductive roller was manufactured and evaluated in various ways. The results are shown in Table 1.

Example 3
As shown in FIG. 5B, the same conditions as in Example 1 except that the sectional area (Sa) of the annular channel is 39.4 mm ² and the sectional area (Sb) of the discharge port is 36.1 mm ^2. A conductive roller was manufactured and evaluated in various ways. The results are shown in Table 1.

Example 4
As shown in FIG. 5C, the conductivity is the same as in Example 1 except that the maximum cross-sectional area (Sc) of the annular channel is 108.5 mm ^{2 and} is slightly larger than (Sa + Sb). A roller was manufactured and subjected to various evaluations. The results are shown in Table 1.

Example 5
As shown in FIG. 5D, the inlet cross-sectional area (Sa) of the annular flow path is 39.4 mm ² , the cross-sectional area (Sb) of the discharge port is 36.1 mm ² , and the maximum cross-sectional area (Sc) is 79.3 mm. ^A conductive roller was produced under the same conditions as in Example 1 except that it was set to ^2, and various evaluations were performed. The results are shown in Table 1.

Example 6
As shown in FIG. 5E, the inlet cross-sectional area (Sa) of the annular channel is 39.4 mm ² , the cross-sectional area (Sb) of the discharge port is 36.1 mm ² , and the maximum cross-sectional area (Sc) is 79.3 mm. ^The conductive roller is manufactured under the same conditions as in Example 1 except that the length of the annular flow path (La) is set to 20 mm, which is 50% of the total flow path length (L) of the annular flow path. Various evaluations were made. The results are shown in Table 1.

[Comparative Example 1]
As shown in FIG. 6 (a), a conductive roller was manufactured in the same manner as in Example 1 except that the channel width of the annular channel was not constant, that is, a coating head having a liquid throttle channel. Various evaluations were made. The results are shown in Table 1.

[Comparative Example 2]
As shown in FIG. 6B, the flow path length (La) of the annular flow path was set to 8 mm, which is 20% of the total flow path length (L) of the annular flow path, as in Example 1. Conductive rollers were manufactured and evaluated in various ways. The results are shown in Table 1.

[Comparative Example 3]
As shown in FIG. 6C, the same conditions as in Example 1 except that the sectional area (Sa) of the annular channel is 39.4 mm ² and the sectional area (Sb) of the discharge port is 65.9 mm ^2. A conductive roller was manufactured and evaluated in various ways. The results are shown in Table 1.

[Comparative Example 4]
Figure 6 except that the maximum cross-sectional area of the annular channel as shown in (d) a (Sc) was 79.3Mm ² is to produce a conductive roller under the same conditions as in Example 1, was subjected to various evaluations . The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Conductive shaft core 3 Conductive rubber layer 101
4 conductive resin layer 5 toner 6 developing container 7 toner supply roller 8 developing blades 10a to d image forming unit 11 photoreceptor 12 charging device (charging roller)
13 Image exposure device (writing beam)
14 Developing device 15 Cleaning device 16 Image transfer device (transfer roller)
17 Transfer conveyance belt 18 Drive roller 19 Tension roller 20 Driven roller 21 Adsorption roller 22 Supply roller 23 Peeling device 24 Fixing device 25 Recording material 26 Bias power supply (for image transfer device (transfer roller) 16)
27 Bias power supply (for suction roller 21)
31 Coating head side mount 32 Coating head side column 33 Coating head side ball screw 34 Coating head side stage 35 Servo motor 36 Pulley 37 Shaft core holding shaft bracket 38 Coating head 39 Shaft core lower holding shaft 40 Shaft core Body holding shaft 41 Supply port 42 First pipe 43 Coating head side guide 44 Coating head fixing table 45 Cylinder side mount 46 Cylinder side column 47 Cylinder side ball screw 48 Cylinder side stage 49 Piston bracket 50 Second pipe 51 Cylinder Side guide 52 Cylinder fixing table 53 Cylinder 54 Piston 60 Inner ring 61 Outer ring 62 Cap ring 63 Distribution chamber annular channel channel width Annular channel inlet cross-sectional area (Sa)
Discharge port cross-sectional area (Sb)
Annular channel maximum cross-sectional area (Sc)
Liquid throttle channel length (La)
Total channel length (L)
DESCRIPTION OF SYMBOLS 101 Conductive rubber layer 102 Shaft core 103 Surface layer 104 Conductive roller 1101, 1102, 1103 Measuring location accuracy of conductive roller

Claims (1)

One supply port for supplying a liquid conductive rubber material containing conductive particles from the outside, a distribution chamber for distributing the liquid conductive rubber material in an annular shape, and an inner periphery of the liquid conductive rubber material Conductive conductive layer having a conductive rubber layer around a cylindrical shaft core using an annular coating head having an annular discharge port for discharging onto a surface and an annular flow path from the distribution chamber to the discharge port In a method of manufacturing a roller,
The width of the annular channel is constant, and the sectional area of the annular channel is (the sectional area of the inlet of the annular channel: Sa)> (the sectional area of the discharge port: Sb), and (the The maximum cross-sectional area in the annular channel: Sc)> (Sa + Sb), and (the channel length from the inlet of the annular channel to the maximum cross-sectional area in the annular channel: La) A method for producing a conductive roller, characterized in that it is 50% or more of the total flow path length from the inlet to the outlet (L).