JP3539550B2 - Conductive member and method of manufacturing the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a conductive member having a gradient resistance, a method for manufacturing the conductive member, and an image forming apparatus such as an electrophotographic apparatus using the conductive member as a contact charging member or the like.
[0002]
[Prior art]
In an image forming apparatus to which the electrophotographic method is applied, in a charging step of charging a surface of a photoconductor or a transfer step of transferring a toner image formed on the surface of a photoconductor to a recording medium, conventionally, a high voltage is applied to a metal wire, The generated corona charges the photoconductor and transfers a toner image. However, in this corona charging method, ozone or NO _x And other corona products. Since the corona product deteriorates the surface of the photoreceptor, there is a problem in image quality such as generation of white spots and black stripes on the image, and also a problem in office environment.
[0003]
So, ozone and NO _x As a method that does not generate a corona product such as that described above, there has been proposed a method in which a conductive member is brought into contact with a photoreceptor or the like and charged and transferred. As a means for constituting the above-mentioned conductive member, the volume resistivity required by the use means is different, but a single-layer conductive member comprising only a base and an elastic layer, a base and an elastic layer having a plurality of volume resistivities Or a function-separated multilayer conductive member comprising a base, an elastic layer, and a layer having a relatively high resistance has been proposed in JP-A-1-142569.
[0004]
[Problems to be solved by the invention]
When a single-layer conductive member composed of only a base and an elastic layer is used as the conductive member, when the single-layer conductive member is brought into contact with a pressure contact member such as a photoconductor and charged and transferred, the single-layer conductive member is Since the surface resistivity of the conductive member is low, there is a problem that a discharge easily occurs between the conductive member and the surface of the photosensitive member.
[0005]
In order to avoid the problem of the discharge, it is effective to increase the surface resistance of the conductive member. Therefore, it is also possible to use a high-resistance layer as it is without removing a skin layer having the same composition as a polymer material constituting an elastic layer, which is usually removed in a manufacturing step of a conductive member which is removed by polishing and grinding. is there. However, in this case, there arises a problem that the hardness of the conductive member itself increases and a nip width with the pressure contact member cannot be sufficiently obtained. If the contact pressure is increased to solve this problem, not only a problem such as abrasion with the pressure contact member but also a problem of so-called C-set on the surface of the conductive member occurs. There is also a problem that cracks occur in the skin layer.
[0006]
Since the above-mentioned problems occur when a single-layer conductive member is used as the conductive member, the functions of the conductive elastic layer, the resistance adjustment layer, and the press-contact member protection layer are different as the conductive member of the actual product. In many cases, a multilayer conductive member having a multilayer structure is employed.
[0007]
However, a multi-layer conductive member composed of a base and an elastic layer having a plurality of volume resistivity as the conductive member, or a functional separation composed of a base, an elastic layer, and a relatively high-resistance layer on its surface. Even when a multi-layered conductive member is used, it is very difficult to join the elastic layers having a plurality of volume resistivity, and between the elastic layer and the relatively high-resistance layer on the surface thereof. Problems such as lifting occur.
[0008]
When a special adhesive is used in the bonding between the layers, a change in the overall volume resistivity or a local change in the volume resistivity may occur due to the resistance of the adhesive. It is also possible to join by a chemical reaction between polymers without using a special adhesive, but even in this case, the change in the overall volume resistivity due to a change in the composition at the joint and the local volume A change in resistivity, a change in hardness, or the like may be caused. Further, not only a complicated technique is required for the manufacturing process, but also a problem such as an extremely high cost arises.
[0009]
Also, when a multilayer conductive member is formed by joining a plurality of conductive elastic layers having different volume resistivity, if the volume resistivity changes abruptly at the joining surface between the layers, discharge occurs between the layers, and the composition changes due to the discharge. For example, the life of the conductive member may be shortened.
[0010]
In order to solve these problems, in Japanese Patent Application Laid-Open No. 10-48916, a high-resistance compound is mixed into the surface of the conductive elastic layer and the vicinity thereof, and the volume resistivity is inclined inward from the surface. A reduced conductive member is proposed. However, according to the means described in the above publication, the solvent of the solution used for mixing the high-resistance compound and unreacted substances during the subsequent heat treatment remain in the conductive member, and these residues ( It is very difficult to remove unreacted monomers, non-reactive additives). It is known that such a residue contaminates a pressing member such as a photoconductor. Further, since a high resistance compound and a solvent are used in the production means, the production cost and time increase. Therefore, in order to eliminate the residue in the conductive member and to reduce the manufacturing cost and the manufacturing time, it is better to use as few substances as possible to manufacture the conductive member.
[0011]
The present invention has been made in order to solve the above problems, and has an object to increase the volume resistivity on the surface of an elastic layer and to use the member as a member for charging and transferring by contacting a pressure contact member such as a photoconductor. An object of the present invention is to provide a conductive member capable of preventing problems caused by discharge on a contact surface when the contact is made, and preventing a reduction in life due to peeling between layers or interlayer discharge.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the conductive member of the present invention includes a base, and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam, The distribution of the conductive material in the layer is continuously inclined and increased from the surface side of the conductive elastic layer toward the substrate side. In the conductive member, the conductive elastic layer is formed of a single layer, and the expansion ratio of the conductive elastic layer increases from the substrate side toward the surface of the conductive elastic layer. It is characterized by having.
[0013]
According to the above configuration, the distribution of the conductive material is increased from the surface of the conductive elastic layer toward the substrate in an inclined manner, so that the surface resistivity of the conductive elastic layer has a higher volume resistivity. For this reason, when the conductive member is used as a member for charging and transferring by contacting with a pressure contact member such as a photoconductor, it is possible to prevent discharge occurring between the photoconductor and the photoconductor. Further, since the distribution of the conductive material in the conductive elastic layer is continuously inclined, the life can be prevented from being shortened by interlayer discharge in a portion where the volume resistivity changes rapidly, and a long life can be achieved.
[0014]
Also Since the foaming ratio increases from the substrate toward the surface of the conductive elastic layer, the distribution of the conductive material is inclined to increase toward the surface of the conductive elastic layer where the foaming ratio increases. It is possible to obtain a sex member. Since the high-resistance layer is simulated on the surface of the conductive elastic layer, the manufacturing process can be simplified and the cost can be reduced. Furthermore, since there is no need to worry about peeling, floating, and cracking of the high resistance layer, which are disadvantages of coating with the high resistance layer, long life can be realized.
[0015]
The conductive member of the present invention includes a base and a single conductive elastic layer formed by dispersing a conductive material in a foam formed on the base to solve the above problem. It is characterized in that the expansion ratio in the conductive elastic layer is maximum near the surface of the conductive elastic layer.
[0016]
According to the configuration, since the expansion ratio in the conductive elastic layer is maximum near the surface of the conductive elastic layer, the volume resistivity is highest on the surface of the conductive elastic layer. For this reason, when the conductive member is used as a member for charging and transferring by contacting with a pressure contact member such as a photoconductor, it is possible to prevent discharge occurring between the photoconductor and the photoconductor. Further, by controlling the volume resistivity of the conductive elastic layer by the expansion ratio, the high-resistance layer is simulated in a single conductive elastic layer, thereby reducing the cost. In addition, since there is no need to worry about peeling, floating, and cracking of the high-resistance layer, which are disadvantages of coating with the high-resistance layer, long life can be realized.
[0017]
The conductive member is characterized in that the expansion ratio in the conductive elastic layer is continuously inclined from the substrate side toward the surface of the conductive elastic layer and increases.
[0018]
As described above, with the expansion ratio in the conductive elastic layer continuously increasing from the substrate side toward the surface side of the conductive elastic layer, the expansion ratio of the conductive material in the conductive elastic layer is increased. Since the distribution also slopes continuously, the life can be prevented from being shortened by interlayer discharge in a portion where the volume resistivity changes rapidly, and a long life can be achieved.
[0019]
Further, the conductive member is characterized in that an ionic conductive material is used as the conductive material. As described above, by using the ion conductive material as the conductive material, it is possible to suppress the change in the volume resistivity with respect to the voltage applied to the conductive member, and to suppress the variation in the volume resistivity distribution of the conductive member. Becomes possible.
[0020]
Further, the conductive member is characterized in that an electronic conductive material is used as the conductive material. As described above, by using an electronic conductive material as the conductive material, it is possible to use the conductive member for a long time without a history even when a voltage is applied to the conductive member.
[0021]
Further, the conductive member is characterized in that the skin layer formed at the stage of forming the foam in the conductive elastic layer is deleted, and the elastic layer having bubbles is exposed on the surface of the conductive member.
[0022]
In the step of forming a foam in which the unfoamed conductive elastic layer is foamed by heating in a mold, a skin layer having almost no air bubbles is formed on the surface of the conductive elastic layer. By removing this skin layer by polishing and grinding, etc., an elastic layer having air bubbles appears on the surface of the conductive member, and the volume resistivity increases as the elastic layer surface increases, and the resistivity of the elastic layer surface is uniform over a wide range. Since the hardness of the conductive member can be reduced without impairing the effect of the pseudo high resistance layer coating, it is possible to prevent abrasion with the pressure contact member. In addition, cracking of the skin layer due to fatigue can be prevented in advance, and a long life can be realized.
[0023]
The method for manufacturing a conductive member according to the present invention is a method for manufacturing a conductive member including a base and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam, wherein a heating foaming step is performed. Then, the unfoamed material forming the conductive elastic layer is foamed in a state where the distribution of the foaming agent increases from the base toward the surface of the unfoamed material.
[0024]
In this way, the unfoamed body is foamed in a state in which the amount of the foaming agent increases from the base toward the surface of the unfoamed body. It can be manufactured. Further, for example, a large number of unfoamed materials having slightly different distribution amounts of the foaming agent are laminated on the substrate, and if the foaming agent is included so as to have a continuous inclination, the foaming agent is foamed to form a conductive material. It is also possible to produce conductive members whose distribution is continuously inclined.
[0025]
The method for producing a conductive member according to the present invention is a method for producing a conductive member, comprising: a base; and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam. The method is characterized in that the unfoamed body forming the conductive elastic layer through a foaming step is foamed under conditions where the temperature of the surface of the unfoamed body is higher than that of the substrate.
[0026]
As described above, by foaming the unfoamed body under the condition that the surface temperature is higher than that of the substrate, foaming on the surface side having a higher temperature is promoted, and the foaming ratio of the foam is highest near the surface. Can be manufactured. Further, at this time, the temperature at the time of foaming is inclined from the foam surface side to the substrate side by heat transfer, so that it is possible to manufacture a conductive member in which the distribution of the conductive material is continuously inclined.
[0027]
The method for producing a conductive member according to the present invention is a method for producing a conductive member, comprising: a base; and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam. The non-foamed body forming the conductive elastic layer through a foaming step is foamed while applying a force (for example, centrifugal force) from the surface of the foamed body toward the base.
[0028]
In this way, by foaming the unfoamed body while applying a force in the direction from the surface to the base, the elastic layer having fewer bubbles and a higher density moves toward the base under the action of the force, Bubbles in the conductive elastic layer are distributed more on the surface side. This makes it possible to manufacture a conductive member in which the expansion ratio of the foam is highest near the surface. At this time, the distribution of the conductive material in the conductive elastic layer is continuously inclined.
[0029]
In the image forming apparatus of the present invention, the above-mentioned conductive member is charged by at least charging the surface of the image carrier, and supplying toner to an electrostatic latent image formed on the surface of the image carrier to visualize the image. And a transfer unit for transferring the toner image formed on the image carrier to a recording medium.
[0030]
When the conductive member is used as a charging unit, the resistivity of the surface of the conductive elastic layer is uniform over a wide range, and therefore, uneven charging does not occur. Therefore, not only can it be possible to obtain an image excellent in quality, but also since a local discharge concentration does not occur due to a local current concentration, a long life can be realized.
[0031]
When the conductive member is used as a developing means, the resistivity of the surface of the conductive elastic layer is uniform over a wide range, so that development unevenness does not occur. Therefore, not only is it possible to obtain an image with excellent quality, but also because local discharge concentration does not occur due to local current concentration, toner sticking to the conductive member can be prevented, and a long life can be realized. It becomes.
[0032]
When the conductive member is used as a transfer unit, it is possible to obtain an effect that the transfer efficiency of the toner in the image formation is good, and the toner does not scatter and the density of the image does not become uneven. Further, an image excellent in quality can be obtained without being affected by the size of the transfer material. Further, not only can the manufacturing cost be reduced, but also a long life can be realized.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
[0034]
The apparatus provided with the conductive member according to the present invention is not particularly limited, but an example in which the conductive member is applied to an image forming apparatus will be described below. In the above-described image forming apparatus, the image forming method on the image carrier necessary for recording an image on the image forming body can use the Carlson process, the backside exposure method, and other various image forming principles. The forming method is not particularly limited. In the present embodiment, an image forming apparatus using the Carlson process will be described as an example.
[0035]
FIG. 3 is a schematic sectional view of the image forming apparatus. The image forming apparatus is used as an output device of a computer, but can also be used as a word processor, a facsimile printing unit, or a digital copier printing unit.
[0036]
The image forming apparatus mainly includes an image forming unit 10 for forming an image and a sheet feeding device 30 for supplying a sheet P to the image forming unit 10.
[0037]
The image forming unit 10 includes a photosensitive drum 11 as an image carrier having a photosensitive layer disposed on an aluminum tube, a charging device 12 disposed around the photosensitive drum 11 in this order, and an exposure device (laser unit). 13), a developing device 14, a transfer device 15, a charge removing device (discharge lamp) 16, and a fixing device 17.
[0038]
The charging device 12 includes a charging roller (charging unit) 18 for applying a uniform charge to the surface of the photoconductor drum 11, and a charging power supply 19 for supplying a potential to the charging roller 18. The laser unit 13 irradiates a laser on the charged surface of the photosensitive drum 11 in accordance with image data, and forms an electrostatic latent image having a charge pattern on the photosensitive drum 11. The developing device 14 includes a developing roller (developing unit) 21 that supplies a toner 50 as a developer to the electrostatic latent image formed by the exposure of the laser unit 13 to form a toner image, A developing power supply 22 for supplying a developing voltage to the roller 21; The transfer device 15 includes a transfer roller (transfer unit) 23 that presses the sheet P against the photosensitive drum 11 to transfer a toner image formed on the photosensitive drum 11 onto the sheet P, and transfers the toner image to the transfer roller 23 during transfer. And a transfer power supply 24 for supplying a voltage. The charge removing lamp 16 is composed of a plurality of LEDs, and irradiates light to the surface of the photosensitive drum 11 to neutralize charges remaining on the surface of the photosensitive drum 11 to remove charges.
[0039]
The paper feed 30 includes a cassette 31 for storing the paper P, a pickup roller 32 for feeding out the paper P from the cassette 31, a paper feed guide 33 for guiding the supplied paper P, and feeding the fed paper P at a predetermined speed. It comprises a pair of registration rollers 34 to be conveyed. Further, the paper feeding device 30 includes a paper feeding sensor (not shown) that detects that the paper P has been supplied.
[0040]
The pickup roller 32, the charging roller 18, the developing roller 21, the transfer roller 23, and the photosensitive drum 11 are driven to rotate by a driving device (not shown). These rotation drives are appropriately controlled at a predetermined timing by a process control unit (not shown). Further, on the paper output side of the paper P of the image forming unit 10, a paper discharge roller 41 for discharging the paper P out of the apparatus and a paper discharge tray 42 for holding the discharged paper P are arranged. In the image forming apparatus having the above configuration, the conductive member according to the present invention can be suitably used for the charging roller 18, the developing roller 21, the transfer roller 23, and the like.
[0041]
1 and 2 are cross-sectional views illustrating the configuration of the conductive member according to the present embodiment. The conductive member has a configuration in which a conductive elastic layer is formed on a base. In FIGS. 1 and 2, reference numeral 2 denotes a base for forming the conductive elastic layer. The base has a planar shape when the conductive member has a blade shape or a belt shape, and has a cylindrical shape when the conductive member has a roller shape or a drum shape. Have. When the conductive member has an endless shape that is endless in a circumferential direction such as a belt shape or a roller shape, the conductive member can be formed without separating from a pressure contact member such as a photoconductor. The surface can be easily cleaned using various means. 1 and 2, reference numeral 4 denotes a conductive conductive agent, and reference numeral 5 denotes air bubbles.
[0042]
The conductive member 1 shown in FIG. 2 has a conductive elastic layer 3 formed by dispersing a conductive conductive agent (conductive material) 4 in a foam on a base 2. In, the bubble ratio increases from the base 2 toward the surface of the elastic layer 3. Here, the bubble ratio represents the ratio of air-containing bubbles per unit volume of the elastic layer. Further, in the conductive member 1 ′ shown in FIG. 3, a conductive elastic layer 3 ′ formed by dispersing a conductive conductive agent 4 in a foam is formed on a base 2, and the conductive elastic layer 3 ′ is formed. In, the diameter of the bubbles 5 of the conductive elastic layer 3 ′ increases from the base 2 toward the surface of the conductive elastic layer 3 ′.
[0043]
The base body 2 is made of iron, aluminum, SUS, brass, etc., and is a so-called “core metal”, a core body made of a thermoplastic resin and / or a thermosetting resin, and a body whose surface is plated, Plastics such as a core formed of a conductive resin molded article in which a conductive resin and / or a thermosetting resin is mixed with a conductive carbon black or a metal powder as a conductivity-imparting agent, or a core formed of a combination thereof; What consists of arbitrary materials selected from metal and ceramic is used.
[0044]
For the conductive elastic layers 3 and 3 ', foams such as rubber, elastomer, and resin can be used as the elastic material.
[0045]
Examples of the elastomer or rubber include ethylene-propylene copolymer (EPDM), styrene-butadiene rubber (SBR), high styrene rubber, butadiene rubber, isoprene rubber, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicon rubber, and fluoro rubber. , Nitrile rubber, urethane rubber, acrylic rubber, natural rubber (NR), epichlorohydrin rubber, norbornene rubber and the like.
[0046]
Further, as resins, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, Styrene-acrylate copolymers (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, and styrene-phenyl acrylate Styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer), styrene-α-chloroacryl Acid methyl copolymer, styrene-acrylonitrile-a Styrene resins such as acrylate copolymers (mono- or copolymers containing styrene or styrene substituents), vinyl chloride resins, rosin-modified maleic resins, phenol resins, epoxy resins, polyester resins, low molecular weight polyethylene , Low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, fluororesin, polycarbonate, polyamide resin, vinyl butyral resin and copolymers and mixtures thereof. No.
[0047]
A conductive conductive agent 4 is appropriately added to the conductive elastic layers 3 and 3 'made of these materials to control the volume resistivity. The volume resistivity is within a range not to impair the object of the present invention, that is, when the conductive member 1 ′ is brought into contact with the photosensitive drum 11, a desired potential is obtained between the conductive member 1 and 1 ′, In addition, control is performed so that the average value of the volume resistivity is about 1.0E2 to 1.0E16 Ω · cm so as not to cause discharge between the photosensitive drum 11 and the surface. The conductive conductive agent 4 includes various conductive inorganic particles (metal powder, metal oxide, etc.), conductive resin, conductive particle dispersed resin, and electronic conductive conductive agent such as carbon black; Conductive agent.
[0048]
Specifically, as the electron conductive conductive agent (electro conductive material), conductive resins such as quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline, polyvinyl pyrrole, polydiacetylene and polyethylene imine, carbon, aluminum, Conductive particle-dispersed resin in which conductive particles such as nickel are dispersed in resins such as urethane, polyester, vinyl acetate-vinyl chloride copolymer and polymethyl methacrylate; metal powder such as aluminum, nickel and stainless steel; titanium oxide , Tin oxide, barium sulfate, aluminum oxide, strontium titanate, magnesium oxide, silicon oxide, silicon carbide, silicon nitride and other conductive inorganic particles, as well as tin oxide, antimony oxide and carbon as required for their whiskers and mica. etc Having been subjected to the surface treatment, or include carbon black. The shape of these electronically conductive agents may be any shape such as spherical, fibrous, plate-like, or amorphous. When an electronic conductive agent is used as the conductive agent 4, the conductive member is conductive due to discharge between the electronic conductive agents, so that even if a voltage is applied to the conductive members 1 and 1 ′ for a long time, a history can be left. It can be used without.
[0049]
Examples of the ion conductive agent (ion conductive material) include lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, and octadecyltrimethyl instead of salts such as lithium perchlorate, sodium perchlorate, and calcium perchlorate. Ammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, modified aliphatic dimethylethylammonium ethosulfate, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, tetrabutylammonium borofluoride, tetrabutylammonium borofluoride, tetrabutyl chloride Quaternary ammonium salts such as ammonium, alkyl sulfonates, phosphate esters, perchlorates and the like. . When an ionic conductive agent is used as the conductive agent 4, the ionic conductive agent and the polar group of the polymer constituting the elastic layers 3.3 ′ are energized, so that the conductive members 1.1 ′ can be supplied to the conductive member 1.1 ′. It is possible to suppress the variation of the volume resistivity with respect to the applied voltage, and to further suppress the variation of the volume resistivity distribution of the conductive members 1.1 ′.
[0050]
Here, the reason why the use of an ionic conductive agent as the conductive agent 4 can suppress the change in volume resistivity with respect to the voltage applied to the conductive members 1 and 1 'is considered to be as follows. That is, when an electronic conductive agent is used, the conductive agent is merely mixed with the elastic layers 3 and 3 'and aggregation of the conductive agent may occur. In this case, polar rubber is adopted as the material of the elastic layers 3 and 3 ', and the conductive agent is dispersed by utilizing the polarity. Thereby, when the ionic conductive agent is used as the conductive agent 4, the conductive agent can be dispersed uniformly, and the variation in the volume resistivity of the elastic layers 3, 3 'can be suppressed. Of course, there is also an effect of the size of the conductive agent. Regarding the variation in resistivity with respect to the applied voltage, when an electronically conductive agent is used, the dispersion state of the conductive agent is poor, and the distance between the conductive agents is relatively long. However, when an ionic conductive agent is used, the dispersed state of the conductive agent is good, and the ionic conductive agent and the elastic layers 3 and 3 ' Since the current is passed through the polar group of the constituting polymer, the current is passed linearly, and the resistivity does not easily fluctuate with respect to the applied voltage.
[0051]
Bubbles 5 of the conductive elastic layers 3.3 ′ are subjected to a polymerization reaction from a monomer as a raw material into a polymer to form a chemical reaction of a functional group of the monomers when the conductive elastic layers 3.3 ′ are formed. As a result, it is a residue due to generation of gas. In addition, bubbles 5 are generated by using a foaming agent such as water, azobisisobutyronitrile (AIBN), azodicarbonamide (ADCA), or 4,4′-oxybisbenzenesulfonyl hydrazide (OBSH) as the raw material. Or mechanically doping the bubbles 5. By the bubbles 5, the hardness of the conductive elastic layers 3 and 3 'can be reduced and appropriate elasticity can be obtained.
[0052]
Subsequently, a basic method for manufacturing the conductive members 1 and 1 'of the present invention will be described below.
[0053]
(Procedure 1)
One or more kinds of unvulcanized and unfoamed rubber materials are combined with one or more of the above-mentioned electronic conductive conductive agents, the above-mentioned foaming agents, and hydrogen or polysiloxane or sulfur in the presence of a peroxide or platinum catalyst. Is uniformly dispersed at a desired ratio and kneaded. At this time, if necessary, additives such as a vulcanization accelerator, a softener, a plasticizer, a reinforcing agent, an antioxidant, and an antistatic agent can be appropriately compounded.
[0054]
(Procedure 2)
A rubber composition obtained by kneading a conductive agent, a foaming agent, a vulcanizing agent and the like into this unvulcanized / unfoamed rubber material is formed by, for example, a method such as press molding, extrusion molding, or injection molding. I do. Among these, a particularly preferable extrusion molding method is to form the above-mentioned unfoamed elastic body (a rubber composition for forming the conductive elastic layers 3.3 ′ by foaming) into a cylindrical shape around a cylindrical substrate 2. It is a way to get it. When obtaining a planar unfoamed elastic body, a rubber composition forming an unfoamed elastic layer is extruded simultaneously with the base 2 using an extruder capable of co-extrusion. In order to obtain an unfoamed elastic body having a planar shape. Then, such an unfoamed elastic body is cut into a predetermined length and placed in a mold having a planar and cylindrical cavity.
[0055]
(Procedure 3)
By performing vulcanization, foaming, and curing by heat treatment on the unfoamed elastic body, a conductive elastic layer 3, 3 'having a shape along the inner peripheral surface of the mold around the base 2 is formed. It is formed so as to be integrated with the base 2 to obtain the desired conductive member 1.1 ′.
[0056]
(Procedure 4)
The skin layer formed on the surface of the conductive elastic layer 3.3 ′ in the treatment of the above-mentioned procedure 3 is removed by polishing and grinding to expose the elastic layer having bubbles on the surface of the conductive member 3.3 ′. This makes it possible to reduce the surface hardness of the conductive members 1 and 1 ′, so that it is possible to prevent abrasion with the pressure contact member such as the photosensitive drum 11. In addition, it is possible to prevent cracking of the skin layer due to fatigue in advance.
[0057]
In the case where an ionic conductive agent is used instead of the electronic conductive agent for the conductive member 4 in the conductive members 1 and 1 ′, the ion conductive agent may be used instead of the electronic conductive agent in the procedure 1. A conductive conductive agent is kneaded. Alternatively, an electronic conductive agent was prepared without dispersing the electronic conductive agent in an unvulcanized / unfoamed rubber material, and the ionic conductive agent was dissolved in the vulcanized / foamed / cured elastic body by heat treatment. The conductive elastic layers 3 and 3 ′ may be formed by immersing the solution.
[0058]
In the above description, the basic method of manufacturing the conductive members 1 and 1 ′ has been described. Hereinafter, a method of manufacturing the conductive member 1 having the configuration illustrated in FIG. 1 will be described. As such a method, for example, the following methods A to C are applicable.
[0059]
(Method A)
In step 2 of the above manufacturing method, as shown in FIGS. 4 and 5, several types of unfoamed elastic layers (unfoamed bodies) 62 formed so as to have different amounts of the foaming agent 61 are formed around the base 2. (In the case of a cylindrical shape: see FIG. 4) or the upper part (in the case of a planar shape: see FIG. 5). At this time, the amount of the foaming agent 61 is gradually increased from the base 2 side to the surface side of the unfoamed elastic layer 62, and molding is performed so that the amount of the foaming agent 61 is the largest on the surface of the unfoamed elastic layer 62. . In the case where the non-foamed elastic layer 62 is mechanically doped with the air bubbles 5, the non-foamed elastic layer 62 is formed while mixing the air bubbles 5 on the surface side of the non-foamed elastic layer 62 so that the air bubbles 5 are increased. I do.
In this method A, it is assumed that the content of the conductive agent in the unfoamed elastic layer 62 before foaming is equal in each layer. When these unfoamed elastic layers 62 are foamed, the expansion ratio increases from the base 2 toward the surface of the conductive elastic layer 3 after foaming due to the difference in the amount of the foaming agent 61 contained in each layer. The expansion ratio represents the ratio of the volume of the conductive elastic layer 3 after heating to the volume of the unfoamed elastic layer 62 before heating. At this time, in the layer having a high expansion ratio, it is apparent that the distribution of the conductive agent decreases with the volume expansion due to the expansion. Further, since the bubbles 5 generated by foaming act as a high-resistance air layer, in a layer having a high foaming ratio, the volume resistivity increases due to a synergistic effect of a decrease in the distribution of the conductive agent and an increase in bubbles 5. .
4 and 5, reference numeral 63 denotes a mold for molding the conductive elastic layer 3 into a desired shape when the unfoamed elastic layer 62 is foamed.
[0060]
(Method B)
In step 3 of the above manufacturing method, the expansion ratio is controlled by partially varying the amount of heat supplied when the unfoamed elastic layer 62 is heated and foamed. Specifically, as shown in FIGS. 6 and 7, in the mold 63, a heating power supply 64a for heating the unfoamed elastic layer 62 from the surface side and a heating power supply 64b for heating from the base 2 side are provided. By manipulating the outputs of the heating power supplies 64a and 64b, the amount of heat supplied can be varied to control the expansion ratio. In the case where the conductive elastic layer 3 having a planar shape is obtained, the mold 63 is insulated by the heat insulating material 65 between the surface side of the unfoamed elastic layer 62 and the base 2 in the configuration of FIG.
At this time, as a method of increasing the expansion ratio on the surface side of the unfoamed elastic layer 62, for example, the output of the heating power supply 64a is made larger than the output of the heating power supply 64b so that the temperature of the surface of the unfoamed elastic layer 62 becomes high. 7, the method of heating only the surface of the unfoamed elastic layer 63 by the output of only the heating power supply 64a, or the method of heating and heating the heating power supply 64a and the heating power supply 64b simultaneously to the mold 63 and the base 2 (in the configuration of FIG. 7). After heating the mold 63 on the side in contact with the base 2, the base 2 is cooled to generate a temperature difference between the mold 63 and the base 2.
By these methods, in the unfoamed elastic layer 62, the surface temperature at which the amount of supplied heat is large becomes higher than the substrate side temperature, and the foaming proceeds more on the surface side, and the foaming ratio increases.
[0061]
(Method C)
In steps 2 and 3 of the above-described manufacturing method, molding and heat treatment are performed with a force F directed from the surface of the unfoamed elastic layer 62 toward the substrate 2 being applied. For example, at the time of forming and heating the unfoamed elastic layer 62, as shown in FIG. 8, the centrifugal force obtained by rotating the unfoamed elastic layer 62 around the axis with the base 2 on the center side and the base 2 on the outside is not affected. The force can be applied as a force F from the surface of the foamed elastic layer 62 toward the substrate 2.
Accordingly, during the foam hardening of the unfoamed elastic layer 62, the heavy elastic layer depends on the direction in which the force F is applied, that is, in the direction of the substrate 2. It is possible to generate an elastic layer having many air bubbles 5 containing. FIG. 8 illustrates a case where only one conductive member including the base 2 and the unfoamed elastic layer 62 is disposed in the mold 63. Can be arranged to further improve the manufacturing efficiency.
[0062]
In the conductive elastic layer 3 formed by the above methods A to C, the volume resistivity is increased on the surface side of the conductive elastic layer 3 and the conductive member 1 is used as a photosensitive member (the conductive member is used as an image forming apparatus). When charged and transferred by being brought into contact with a pressure contact member such as a charging member or a transfer member, it is possible to prevent discharge from occurring between the photosensitive member surface.
[0063]
In the methods B and C, the expansion ratio of the conductive elastic layer 3 is determined by the amount of heat supplied during heating or the force (centrifugal force or the like) F applied during heating from the base 2 side to the conductive elastic layer 3. And the distribution of the conductive conductive agent increases from the surface side of the conductive elastic layer 3 to the substrate 2 side. At this time, since the supplied heat amount and the force F act on the whole of the conductive elastic layer 3, there is no portion where the distribution of the conductive agent changes intermittently, and the distribution of the conductive agent is continuous. It becomes a slope. Further, also in the method A, if the number of the unfoamed elastic layers 62 formed on the base 2 is increased and the difference in the content of the foaming agent 61 between the layers is reduced, the conductive elastic layer after foaming can be obtained. In No. 3, a continuous inclination of the conductive agent can be realized. The advantages of making the distribution of the conductive agent a continuous slope are as follows. That is, if there is a layer in the conductive elastic layer 3 whose volume resistivity changes abruptly in the thickness direction, a discharge occurs between the layers and a change in composition due to the discharge may cause a reduction in the life of the conductive member. There is. On the other hand, if the distribution of the conductive conductive agent in the conductive elastic layer 3 is made to have a continuous slope, a layer in which the volume resistivity changes abruptly does not occur, and the above problem can be avoided.
[0064]
Further, the conductive elastic layer 3 of the conductive member 1 manufactured by the methods A to C has a single-layer structure, and can realize the inclination of the conductive conductive agent. Therefore, unlike the case where a plurality of conductive elastic layers having different volume resistivities are joined with an adhesive, peeling or floating between joints does not occur.
[0065]
In the methods A and B, the bubbles 5 generated in the elastic layer 3 are due to a chemical reaction of the functional group of the monomer in the bubbles 5 over the entire elastic layer 3, and the bubbles 5 present on the surface of the elastic layer 3 are many. Is due to the foaming agent 61. This is apparent from the fact that a large amount of the foaming agent 61 exists on the surface of the elastic layer 3 in the method A, but also in the method B, the degree of exhibiting the firing effect due to the temperature distribution inclination is inclined inside the elastic layer 3. In addition, a large number of bubbles existing on the surface of the elastic layer 3 are caused by the foaming agent 61.
[0066]
By performing one or more of the above methods A, B, and C, the conductive member 1 having at least one elastic layer 3 shown in FIG. 1 can be manufactured.
[0067]
In addition, by performing only the step A, or the step A and any one of the steps B and C, or the steps A, B and C, the conductive layer having at least one elastic layer 3 ′ shown in FIG. The member 1 'can be manufactured. At this time, it is necessary to include the above-mentioned step A. This is because the density of the foaming agent 61 is large in the unfoamed elastic layer 62 near the surface side and the distance between the foaming agents 61 is small. This is because bubbles formed by the foaming agent 61 grow while fusing, and the diameter of the bubbles on the surface side increases.
[0068]
The characteristics of the conductive member prepared by the method according to the present embodiment are shown in Examples 1 to 4 below.
[0069]
[Example 1]
60 parts of carbon black as a conductive agent, 5 parts of azodicarbonamide (ADCA) as a foaming agent, and other additives such as a vulcanizing agent (sulfur, etc.) are appropriately added to 100 parts of EPDM as an elastic layer material. The mixture was kneaded with an open roll and kneaded to prepare a first rubber composition that forms an unfoamed elastic layer. Subsequently, a second rubber composition for forming an unfoamed elastic layer was prepared by mixing 10 parts of the foaming agent ADCA in the above composition. These first and second rubber compositions were extruded using a die to produce flat and cylindrical unfoamed elastic layers. The unfoamed elastic layer is formed by laminating the first and second rubber compositions. The second rubber composition containing more foaming agent is on the front side, and the first rubber composition is on the base side. Become.
[0070]
A flat plate (30 mm long, 200 mm long, 5 mm thick stainless steel plate) was adhered to the unfoamed elastic layer as a substrate, or a metal core (a stainless steel round bar having a diameter of 6 mm and a length of 250 mm) was passed through. The product was subjected to a heat treatment (200 ° C., 20 minutes) in a mold, vulcanized, foamed, and cured to obtain a foamed elastic body (conductive elastic layer) having a shape along the inner peripheral surface of the mold. . Thereafter, the skin layer formed on the surface was polished and ground to obtain a target conductive member having the configuration shown in FIG.
[0071]
The dimensions of the foamed elastic layer were 5 mm in thickness and 200 mm in length. The bubble ratio on the surface of the foamed elastic layer was about twice the bubble ratio of the elastic layer near the substrate. The charged amount of the rubber composition was 30% by volume when the volume of the base and the mold was 100. The hardness of the conductive foamed elastic layer was Asker C 32 °, and the average of the volume resistance values of the conductive members of this example was 1.0E7Ω · cm. FIG. 9 shows the change in the volume elastic modulus of the foamed elastic layer in the layer thickness direction. From the figure, it can be seen that, in the foamed elastic layer, the bulk modulus continuously increases from the substrate side to the surface side.
[0072]
[Example 2]
60 parts of carbon black as a conductive agent, 15 parts of azodicarbonamide (ADCA) as a foaming agent, and other additives such as a vulcanizing agent (sulfur, etc.) are appropriately added to 100 parts of EPDM as an elastic layer material. It was compounded and kneaded with an open roll to prepare a rubber composition that forms an unfoamed elastic layer. This rubber composition was extruded using a die to produce a flat and cylindrical unfoamed elastic layer. A substrate (30 mm long, 200 mm long, 5 mm thick stainless steel plate) adhered to the unfoamed elastic layer or a metal core (a stainless steel round bar having a diameter of 6 mm and a length of 250 mm) was passed through as a substrate. In the mold, heat treatment is performed for 20 minutes under the condition that the temperature of the mold surface is 200 ° C. and the temperature of the substrate side is 100 ° C., and vulcanization / foaming / curing is performed, and along the inner peripheral surface of the mold. A foamed elastic body having a bent shape was obtained. Thereafter, the skin layer formed on the surface was polished and ground to obtain a target conductive member having the configuration shown in FIG.
[0073]
The dimensions of the foamed elastic layer were 5 mm in thickness and 200 mm in length. The bubble ratio on the surface of the foamed elastic layer was about twice the bubble ratio of the elastic layer near the substrate. The charged amount of the rubber composition was 30% by volume when the volume of the base and the mold was 100. The hardness of the conductive foamed elastic layer was Asker C 32 °, and the average of the volume resistance values of the conductive members of this example was 1.0E7Ω · cm. Further, the change in the bulk modulus in the thickness direction of the foamed elastic layer was substantially the same as the distribution shown in FIG.
[0074]
[Example 3]
60 parts of carbon black as a conductive agent, 15 parts of azodicarbonamide (ADCA) as a foaming agent, and other additives such as a vulcanizing agent (sulfur, etc.) are appropriately added to 100 parts of EPDM as an elastic layer material. It was compounded and kneaded with an open roll to prepare a rubber composition that forms an unfoamed elastic layer. This rubber composition was extruded using a die to produce a flat and cylindrical unfoamed elastic layer. A plate (30 mm long, 200 mm long, 5 mm thick stainless steel plate) adhered to the unfoamed elastic layer as a substrate is placed in the mold in a state where the plate is located on the outer periphery of the mold. The mold was rotated, heated (200 ° C., 20 minutes), vulcanized, foamed, and cured to obtain a foamed elastic body having a shape along the inner peripheral surface of the mold. Thereafter, the skin layer formed on the surface was polished and ground to obtain a target conductive member having the configuration shown in FIG.
[0075]
The dimensions of the foamed elastic layer were 5 mm in thickness and 200 mm in length. The bubble ratio on the surface of the foamed elastic layer was about twice the bubble ratio of the elastic layer near the substrate. The charged amount of the rubber composition was 30% by volume when the volume of the base and the mold was 100. The hardness of the conductive foamed elastic layer was Asker C 32 °, and the average of the volume resistance values of the conductive members of this example was 1.0E7Ω · cm. Further, the change in the bulk modulus in the thickness direction of the foamed elastic layer was substantially the same as the distribution shown in FIG.
[0076]
[Example 4]
60 parts of carbon black as a conductive agent, 5 parts of azodicarbonamide (ADCA) as a foaming agent, and other additives such as a vulcanizing agent (sulfur, etc.) are appropriately added to 100 parts of EPDM as an elastic layer material. The mixture was kneaded with an open roll and kneaded to prepare a first rubber composition that forms an unfoamed elastic layer. Subsequently, a second rubber composition for forming an unfoamed elastic layer was prepared by mixing 10 parts of the foaming agent ADCA in the above composition. These first and second rubber compositions were extruded using a die to produce a planar unfoamed elastic layer. The unfoamed elastic layer is formed by laminating the first and second rubber compositions. The second rubber composition containing more foaming agent is on the front side, and the first rubber composition is on the base side. Become.
[0077]
A plate (30 mm long, 200 mm long, 5 mm thick stainless steel plate) adhered to the unfoamed elastic layer as a substrate is rotated in the mold with the plate positioned on the outer periphery of the mold. Then, a heat treatment (200 ° C., 20 minutes) was performed, followed by vulcanization, foaming, and curing to obtain a foamed elastic body having a shape along the inner peripheral surface of the mold. Thereafter, the skin layer formed on the surface was polished and ground to obtain a target conductive member having the configuration shown in FIG.
[0078]
The dimensions of the foamed elastic layer were 5 mm in thickness and 200 mm in length. The bubble ratio on the surface of the foamed elastic layer was about twice the bubble ratio of the elastic layer near the substrate. The average cell diameter on the surface of the foamed elastic layer was 200 μm, and the average cell diameter on the elastic layer near the substrate was 50 μm. The charged amount of the rubber composition was 30% by volume when the volume of the base and the mold was 100. The hardness of the conductive foamed elastic layer was Asker C 32 °, and the average of the volume resistance values of the conductive members of this example was 1.0E7Ω · cm. Further, the change in the bulk modulus in the thickness direction of the foamed elastic layer was substantially the same as the distribution shown in FIG.
[0079]
In the conductive member having the structure as shown in the above Examples 1 to 4, the number of air bubbles decreases from the surface of the conductive elastic layer toward the substrate, and the distribution of the conductive conductive agent is continuously inclined. Is increasing. Thereby, the volume resistivity increases as the surface of the conductive elastic layer increases, and it is possible to obtain the effect of covering the high resistance layer, in which the resistivity of the surface of the conductive elastic layer is uniform over a wide range.
[0080]
Further, in the above-described conductive member, since the high-resistance layer is simulated as a single layer, the manufacturing process can be simplified and the cost can be reduced. Further, since the resistivity of the surface of the conductive member is high, it is possible to prevent a discharge phenomenon caused by dielectric breakdown in a minute gap between the conductive member and the press-contact member or between the member facing the conductive member. In addition, since there is no need to worry about peeling, floating, and cracking of the high-resistance layer, which are disadvantages of coating with the high-resistance layer, long life can be realized.
[0081]
When the conductive member according to the present embodiment is used in the image forming apparatus shown in FIG. 3, it can be suitably used for a charging unit, a developing unit, a transfer unit, or the like.
[0082]
In the image forming apparatus, when the conductive member is used as a charging unit, FIG. 3 shows an example in which the charging unit is used as a charging roller. However, the shape of the charging unit is not necessarily limited to the roller shape, and may be a belt shape or a blade shape. It is also possible to make the shape.
[0083]
Further, the conductive member used as the charging means can be used not only for charging the photosensitive drum but also for charging the transfer-receiving member. Since the resistivity of the surface of the conductive elastic layer is uniform over a wide range, the conductive member does not cause uneven charging when used as a charging unit, and can provide an image excellent in quality. Become. Furthermore, since local discharge concentration due to current concentration does not occur from a locally low resistivity portion of the surface of the conductive member, a long life can be realized.
[0084]
In the image forming apparatus, when the conductive member is used as a developing unit, FIG. 3 shows an example in which the conductive member is used as a developing roller. However, the shape of the developing unit is not necessarily limited to a roller shape, but may be a belt shape. Alternatively, it is also possible to form a blade.
[0085]
Since the resistivity of the surface of the conductive elastic layer is uniform over a wide range, the conductive member does not cause uneven development when used as a developing means, and can provide an image excellent in quality. Become.
[0086]
Furthermore, since local discharge concentration due to current concentration does not occur from the locally low resistivity portion of the surface of the conductive member, toner sticking to the conductive member can be prevented, and a long life can be realized. The conductive member is not limited to a toner carrier such as a developing roller, but can be used as a doctor blade as a toner layer regulating member.
[0087]
In the image forming apparatus, when the conductive member is used as a transfer unit, FIG. 3 shows an example in which the conductive member is used as a transfer roller. However, the shape of the transfer unit is not necessarily limited to the roller shape, but may be a belt shape. , A blade or a drum. Further, the conductive member can be used for an intermediate transfer member or the like.
[0088]
By using the conductive member according to the present embodiment for the transfer unit, it is possible to obtain an effect that the transfer efficiency of the toner in the image formation is good, and the scattering of the toner and the uneven density of the image do not occur. Further, an image excellent in quality can be obtained without being affected by the size of the transfer material. Furthermore, not only can the manufacturing cost be reduced, but also a long life can be realized.
[0089]
【The invention's effect】
In order to solve the above problems, the conductive member of the present invention includes a base, and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam, The distribution of the conductive material in the layer is continuously inclined and increased from the surface side of the conductive elastic layer toward the substrate side. In the conductive member, the conductive elastic layer is formed of a single layer, and the expansion ratio of the conductive elastic layer increases from the substrate side toward the surface of the conductive elastic layer. Configuration.
[0090]
Therefore, the volume resistivity is higher at the surface of the conductive elastic layer, and when the conductive member is used as a member for charging and transferring by contacting with a pressure-contact member such as a photoconductor, a gap between the conductive member and the surface of the photoconductor is reduced. Can be prevented from occurring. Further, since the distribution of the conductive material in the conductive elastic layer is continuously inclined, the life can be prevented from being shortened by interlayer discharge in a portion where the volume resistivity changes rapidly, and a long life can be achieved.
[0091]
Also In addition, it is possible to obtain a conductive member in which the distribution of the conductive material is increased inclining toward the surface of the conductive elastic layer having a higher foaming ratio. Since the high-resistance layer is simulated on the surface side of the conductive elastic layer, the manufacturing process can be simplified, the cost can be reduced, and the high-resistance layer peels off, which is a disadvantage of coating the high-resistance layer. Since there is no need to worry about rising, cracking, etc., there is an effect that a long life can be realized.
[0092]
The conductive member of the present invention includes a base and a single conductive elastic layer formed by dispersing a conductive material in a foam formed on the base to solve the above problem. In this configuration, the expansion ratio in the conductive elastic layer is maximum near the surface of the conductive elastic layer.
[0093]
Therefore, the volume resistivity is highest on the surface of the conductive elastic layer, and when the conductive member is used as a member for charging and transferring by contacting with a pressure-contact member such as a photoconductor, the contact between the conductive member and the photoconductor surface is reduced. It is possible to prevent a discharge occurring between them. Furthermore, by controlling the volume resistivity of the conductive elastic layer by the expansion ratio, the high-resistance layer is simulated in a single conductive elastic layer. There is no need to worry about peeling, floating, cracking, etc. of the high resistance layer, which is a demerit due to layer coating, so that there is an effect that a long life can be realized.
[0094]
The conductive member has a configuration in which the expansion ratio in the conductive elastic layer is continuously inclined from the substrate side to the surface side of the conductive elastic layer and increases.
[0095]
Therefore, as the expansion ratio in the conductive elastic layer continuously increases from the substrate side toward the surface of the conductive elastic layer, the distribution of the conductive material in the conductive elastic layer increases. Is also continuously inclined, so that it is possible to prevent the life from being shortened by interlayer discharge in a portion where the volume resistivity changes abruptly, and to achieve an effect that a long life can be achieved.
[0096]
Further, the conductive member has a configuration in which an ion conductive material is used as the conductive material. As described above, by using an ionic conductive material as the conductive material, it is possible to suppress the change in the volume resistivity with respect to the voltage applied to the conductive member and the variation in the volume resistivity distribution of the conductive member. It works.
[0097]
Further, the conductive member has a configuration in which an electronic conductive material is used as the conductive material. As described above, by using an electronic conductive material as the conductive material, there is an effect that the conductive member can be used without a history even if a voltage is applied to the conductive member for a long time.
[0098]
Further, the conductive member has a configuration in which a skin layer formed in a step of forming a foam in the conductive elastic layer is deleted, and an elastic layer having bubbles is exposed on the surface of the conductive member.
[0099]
Therefore, by removing the skin layer by polishing and grinding, etc., an elastic layer having bubbles appears on the surface of the conductive member, the volume resistivity increases as the elastic layer surface increases, and the resistivity of the elastic layer surface increases over a wide range. Since the hardness of the conductive member can be reduced without impairing the effect of the pseudo high resistance layer coating that is uniform over the entire surface, the effect of preventing abrasion with the pressure contact member can be prevented. Play. In addition, it is possible to prevent the skin layer from cracking due to fatigue in advance, and it is possible to achieve a long life.
[0100]
The method for manufacturing a conductive member according to the present invention is a method for manufacturing a conductive member including a base and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam, wherein a heating foaming step is performed. Then, the non-foamed material forming the conductive elastic layer is foamed in a state where the distribution amount of the foaming agent increases from the substrate toward the surface of the unfoamed material.
[0101]
Therefore, the above-mentioned unfoamed body is foamed in a state in which the amount of the foaming agent increases from the base toward the surface of the unfoamed body, thereby producing a conductive member in which the expansion ratio of the foam is highest near the surface. can do.
[0102]
The method for producing a conductive member according to the present invention is a method for producing a conductive member, comprising: a base; and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam. The non-foamed body forming the conductive elastic layer through a foaming step is foamed under conditions where the temperature of the surface of the unfoamed body is higher than that of the substrate.
[0103]
Therefore, foaming on the surface side where the temperature is high is promoted, and it is possible to manufacture a conductive member in which the foaming ratio of the foam is highest near the surface. At this time, a conductive member in which the distribution of the conductive material is continuously inclined can be manufactured.
[0104]
The method for producing a conductive member according to the present invention is a method for producing a conductive member, comprising: a base; and a conductive elastic layer formed on the base and having a conductive material dispersed in a foam. The non-foamed body forming the conductive elastic layer through a foaming step is foamed while applying a force (for example, centrifugal force) from the surface of the foamed body to the base.
[0105]
Therefore, the elastic layer having a small number of bubbles and having a high density moves toward the substrate under the action of the above-mentioned force, and the bubbles in the conductive elastic layer are distributed more on the surface side. This makes it possible to manufacture a conductive member in which the expansion ratio of the foam is highest near the surface. At this time, the distribution of the conductive material in the conductive elastic layer is continuously inclined.
[0106]
In the image forming apparatus of the present invention, the above-mentioned conductive member is charged by at least charging the surface of the image carrier, and supplying toner to an electrostatic latent image formed on the surface of the image carrier to visualize the image. And a transfer unit for transferring the toner image formed on the image carrier to a recording medium.
[0107]
When the conductive member is used as a charging unit, the resistivity of the surface of the conductive elastic layer is uniform over a wide range, and therefore, uneven charging does not occur. Therefore, not only can it be possible to obtain an image excellent in quality, but also since a local discharge concentration does not occur due to a local current concentration, a long life can be realized.
[0108]
When the conductive member is used as a developing means, the resistivity of the surface of the conductive elastic layer is uniform over a wide range, so that development unevenness does not occur. Therefore, not only is it possible to obtain an image with excellent quality, but also because local discharge concentration does not occur due to local current concentration, toner sticking to the conductive member can be prevented, and a long life can be realized. It becomes.
[0109]
When the conductive member is used as a transfer unit, it is possible to obtain an effect that the transfer efficiency of the toner in the image formation is good, and the toner does not scatter and the density of the image does not become uneven. Further, an image excellent in quality can be obtained without being affected by the size of the transfer material. Further, not only can the manufacturing cost be reduced, but also a long life can be realized.
[Brief description of the drawings]
FIG. 1 illustrates one embodiment of the present invention, and is a cross-sectional view illustrating a schematic configuration of a conductive member.
FIG. 2 illustrates another embodiment of the present invention, and is a cross-sectional view illustrating a schematic configuration of a conductive member.
FIG. 3 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus as an application example of the conductive member of the present invention.
FIG. 4 is an explanatory view showing an example of a foaming step in the method for producing a conductive member.
FIG. 5 is an explanatory view showing another example of the foaming step in the method for producing a conductive member.
FIG. 6 is an explanatory view showing still another example of the foaming step in the method for producing a conductive member.
FIG. 7 is an explanatory view showing still another example of the foaming step in the method for producing a conductive member.
FIG. 8 is an explanatory view showing still another example of the foaming step in the method for producing a conductive member.
FIG. 9 is a graph showing a change in volume resistivity in a thickness direction of a conductive elastic layer of the conductive member.
[Explanation of symbols]
1.1 'conductive material
2 Substrate
3.3 'conductive conductive agent
4 Conductive conductive agent (conductive material)
5 bubbles
11 Photoconductor drum (image carrier)
18 Charging roller (charging means)
21 Developing roller (developing means)
23 Transfer roller (transfer means)
62 Unfoamed elastic layer (unfoamed body)

Claims (10)

A substrate;
Comprising a conductive elastic layer formed on the substrate and dispersing a conductive material in a foam,
The distribution of the conductive material in the conductive elastic layer is continuously inclined and increased from the surface side of the conductive elastic layer toward the substrate side ,
A conductive member, wherein the conductive elastic layer is formed of a single layer, and the expansion ratio of the conductive elastic layer increases from the substrate side toward the surface of the conductive elastic layer . A substrate;
A single conductive elastic layer formed on the substrate and dispersing a conductive material in a foam,
A conductive member, wherein the expansion ratio in the conductive elastic layer is maximum near the surface of the conductive elastic layer. 3. The conductive member according to claim 2 , wherein a foaming ratio in the conductive elastic layer is continuously inclined and increases from the substrate side toward the surface of the conductive elastic layer. The conductive member according to claim 1 or 2, characterized in that ion-conductive material is used as the conductive material. The conductive member according to claim 1 or 2, characterized in that the electron conductive material as the conductive material has been used. The conductive layer according to claim 1 or 2 , wherein a skin layer formed in a step of forming a foam in the conductive elastic layer is deleted, and an elastic layer having bubbles is exposed on the surface of the conductive member. Sex members. A substrate;
A method for producing a conductive member, comprising: a conductive elastic layer formed by dispersing a conductive material in a foam formed on the base;
Manufacturing a conductive member, wherein the unfoamed material forming the conductive elastic layer through a heating foaming step is foamed in a state where the amount of the foaming agent increases from the substrate toward the surface of the unfoamed material. Method. A substrate;
A method for producing a conductive member, comprising: a conductive elastic layer formed by dispersing a conductive material in a foam formed on the base;
A method for producing a conductive member, comprising: foaming an unfoamed body, which forms the conductive elastic layer through a heating foaming step, under conditions where the temperature of the surface of the unfoamed body is higher than that of a substrate. A substrate;
A method for producing a conductive member, comprising: a conductive elastic layer formed by dispersing a conductive material in a foam formed on the base;
A method for producing a conductive member, comprising: foaming an unfoamed body forming the conductive elastic layer through a heating foaming step while applying a force in a direction from the surface of the foamed body to the base. The conductive member according to any one of claims 1 to 6, at least, a charging means for contact-charging the surface of the image bearing member supplies toner to the electrostatic latent image formed on the image carrier surface visible An image forming apparatus comprising: a developing unit configured to convert the toner image formed on the image carrier to a recording medium;

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