JP2006090454A - Method of manufacturing elastic roller, process cartridge, and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an elastic roller by pouring elastic layer material in a mold by which the outer diameter of the roller is equalized so that a difference in outer diameter of the roller in its longitudinal direction is not larger than 5 μm even when the curing temperature is increased to shorten the molding cycle. <P>SOLUTION: When molding the elastic roller by pouring and curing the elastic layer material in the mold retaining a core bar, the temperature of the mold on the material pouring side is made higher than that of the mold on the outlet side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing an elastic roller, particularly an elastic roller useful as a developer carrying roller for use in an image forming apparatus using the principle of electrophotography, and the elastic roller manufactured by the method is incorporated as a developer carrying roller. The present invention relates to a process cartridge and an image forming apparatus.

  Conventionally, a developer carrying roller disposed in contact with or in close proximity to the image forming body is supplied with a developer (hereinafter, sometimes referred to as “toner”) to the image forming body so that the surface is visible on the image forming body. As a developing method for forming an image, a one-component developing method is known. In this one-component development method, toner is adhered to the surface of the developer carrying roller, the layer thickness of the adhered toner is made uniform by the layer thickness regulating member, and the toner is charged by friction with the layer thickness regulating member, In this method, an image formed as a latent image on the surface of the image forming body is visualized by toner transfer by bringing a developer carrying roller into contact with or close to the forming body.

  When the developer carrying roller is brought into contact with the image forming body, the width of the contact portion with the image forming body is required to be uniform in the longitudinal direction. In the case of proximity, the facing gap between the image forming body and the developer carrying roller is required to be uniform in the longitudinal direction. Therefore, it is a very important requirement that the outer diameter shape of the developer carrying roller is uniform in the longitudinal direction.

  As a manufacturing method for obtaining a conductive elastic layer necessary for such a developer carrying roller, a method of polishing with high accuracy has been proposed. That is, it is a method in which a core metal is press-fitted into a tube extruded to an appropriate thickness and then polished into a desired shape. According to this method, it is possible to obtain a conductive elastic layer having a somewhat uniform outer diameter in the longitudinal direction of the conductive elastic layer, but two steps of an extrusion process and a polishing process are required, which increases work efficiency. Is a problem in terms of cost, and in order to obtain a highly accurate roller with a uniform outer diameter, it is necessary to lengthen the polishing time. It is a technology that requires improvement.

  In contrast, a cored bar is placed in a cylindrical mold whose inner diameter shape is processed with high accuracy, and then a raw material is poured into the mold and cured by heating to obtain a conductive elastic layer. An injection molding method has been proposed. According to this, a developer carrying roller having a highly accurate conductive elastic layer substantially reflecting the shape of the mold can be obtained by using a molding die processed with high accuracy. In addition, since the surface accuracy is good, it is possible to obtain a developer carrying roller having a desired uniform conductive elastic layer without polishing after molding, so that it has been widely used in recent years.

  However, even in injection molding using a mold having a high inner diameter, it is difficult to obtain a roller whose outer diameter is sufficiently uniform in the longitudinal direction due to the difference in heat history applied to the material of each part of the roller during curing. Currently, there is a difference in outer diameter of several μm to several tens of μm in the longitudinal direction of the roller. Further, if the curing temperature is increased to shorten the molding processing time, the tendency becomes more prominent and becomes a problem. It was.

  For such a problem, a technique has been proposed in which the heat history applied to each part of the roller conductive elastic layer during curing is made uniform by feedback controlling the temperature rise state of the mold after the raw material is injected (for example, Patent Document 1).

  However, according to this method, after injecting the raw material into the mold, feedback control is performed so that the temperature of each part of the mold is uniformly increased, so that the temperature is increased from room temperature to the temperature required for curing. It takes time, and the temperature feedback control system is complicated, which is disadvantageous for shortening the molding processing time and reducing the cost.

  For these reasons, a method of injecting a raw material into a mold that has been heated to a temperature necessary for curing in advance has been used at present. Even in this method, in order to obtain a roller with high outer diameter accuracy, the temperature of each part of the mold is highly uniformed in order to make the thermal history of each part of the conductive elastic layer as uniform as possible. A method has been proposed (for example, Patent Document 2).

  According to such a method, in processing in a relatively low temperature region of 100 to 120 ° C., it becomes possible to keep the roller outer diameter difference within a range of several μm in the longitudinal direction. In order to shorten the temperature, it is required to increase the curing temperature. In that case, the difference in the amount of heat applied between the material injection side and the filling end (exit side) becomes large, and the roller outer diameter difference becomes large. It was a problem.

From such a background, it is not enough to make the temperature of the mold during the conventional curing uniform in order to shorten the roller processing time, increase the printing speed in recent years, and increase the image definition. It was.
JP 2003-39450 A JP 2003-184862 A

  Therefore, the present invention is processed at a high temperature to shorten the processing cycle in the process of injecting a thermosetting elastic layer material into a pre-heated mold, which is difficult in the prior art, and manufacturing an elastic roller. Even in this case, an object of the present invention is to provide a method for producing an elastic roller in which the outer diameter difference in the roller longitudinal direction is uniformized to 5 μm or less.

  The object of the present invention is achieved by the following.

  That is, the present invention has a thermosetting elastic layer on the outer periphery of the core metal by injecting a thermosetting elastic layer raw material from one end of a cylindrical mold provided with a core metal and then heat-curing it. When producing an elastic roller, the temperature of the cylindrical molding die is set lower on the opposite side (outlet side) than on the raw material injection side during raw material injection and heat curing. It is a manufacturing method.

  The present invention also provides the method for producing the elastic roller, wherein the thermosetting elastic layer material is an addition reaction cross-linkable liquid silicone rubber.

  Furthermore, the present invention is the above-described elastic roller manufacturing method in which the elastic layer has conductivity.

  Furthermore, the present invention is the above-described elastic roller manufacturing method, wherein the elastic roller is a developer carrying roller.

  The present invention also provides an electrophotographic process cartridge and an image forming apparatus in which the elastic roller manufactured as described above is incorporated as a developer carrying roller.

  According to the manufacturing method of the present invention, in order to shorten the processing time in manufacturing a developer carrying roller in an electrophotographic process cartridge incorporated in an electrophotographic apparatus that will be required to have higher speed and higher definition in the future. It is possible to provide a developer-carrying roller whose outer diameter in the longitudinal direction of the roller is uniformed to a submicron or less even when processing is performed. By incorporating the roller manufactured by the manufacturing method, a process cartridge and an image forming apparatus The quality of the printed image is improved.

  As a result of intensive studies in order to solve the above problems, the inventors of the present invention have manufactured an elastic roller by supporting the both ends in a cylindrical mold and placing a cored bar so that the temperature can be cured. A thermosetting elastic layer raw material is injected from one side of the mold that is warmed, and is cured together with the injection, but since the raw material is injected from one side, the temperature in the longitudinal direction of the mold is kept uniform. The amount of heat applied to the injected raw material has a large difference between the raw material injection side and the opposite side (exit side), and as a result, it has been found that an outer diameter difference occurs in the longitudinal direction of the roller in the formed elastic layer. .

  Therefore, as the temperature of the mold is increased in order to shorten the processing time, a difference occurs in the heat history applied to the material on the injection side and the outlet side, and the difference in the outer diameter appears remarkably.

  In the present invention, the temperature on the raw material injection side and the outlet side is controlled from the viewpoint of equalizing the thermal history applied to the formed elastic layer, rather than equalizing the temperature in the longitudinal direction of the mold. Accordingly, even if the curing temperature is raised and the processing time is shortened, the difference in the outer diameter of the roller in the longitudinal direction can be kept to 5 μm or less.

  FIG. 1 is a cross-sectional view showing an example of an elastic roller manufactured according to the present invention.

  The elastic roller of the present invention has, for example, natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, (meth) acrylonitrile butadiene rubber, ethylene propylene rubber, ethylene propylene diene rubber, butyl rubber, halogenated butyl rubber around the core 1. An elastic layer formed by injecting raw materials such as silicone rubber, fluorine rubber, urethane rubber, ethylene vinyl acetate copolymer, ethylene- (meth) acrylate rubber, epichlorohydrin rubber, etc. into a mold, and if necessary foamed and cured 2.

  FIG. 2 shows a schematic cross-sectional view of an example of a mold suitable for use in the production of the elastic roller in the present invention.

  In the figure, a piece 4 having a raw material supply path 4a for holding a cored bar 1 of a roller and supplying a raw material for an elastic layer to an elastic layer forming cavity 3 in the mold and a raw material are supplied into the cavity 3 and cured. And a piece 5 for holding the metal core 1 together with the piece 4, having an exhaust passage 5 a overflowing the air in the cavity 3 and the excess of the raw material supplied slightly more than the volume of the cavity 3. It consists of a pipe-shaped mold 6 that forms the elastic layer forming cavity 3 together with the pieces 4 and 5. Here, the piece 4 and the piece 5 may have the same shape or may be changed in shape in consideration of their respective functions. If they have the same shape, a molding die is set in the injection molding machine. It is preferable because the direction is not determined.

  In the present invention, when injecting the elastic layer material into the mold, it is important to keep the mold at the curing temperature of the material and to keep the temperature on the material injection side higher than the outlet side. . The temperature difference varies depending on the elastic layer material. Moreover, it is preferable to set so that it may fall gradually from the injection | pouring side to an exit side, and even if it falls continuously, it does not matter even if it falls gradually. Therefore, it is preferable to change appropriately the heating mechanism provided in the hot platen which hold | maintains the shaping | molding die of an injection molding machine. For example, in the case of an electric heating type, the temperature at the injection side and the outlet side of the mold is controlled by appropriately changing the winding interval of the heater wire or dividing the heating section into several parts and controlling the temperature individually. To do. Note that the temperature difference between the injection side and the outlet side differs depending on the elastic layer material with the curing temperature, shrinkage after curing, etc., and also varies depending on the rubber thickness of the same material and the like. It is desirable to obtain the temperature difference within which the obtained elastic roller fits within a predetermined external dimension difference for each raw material type used for molding, and for each rubber part thickness.

  The elastic layer of the elastic roller is formed by curing the elastic layer raw material as described above. Since the outer diameter in the longitudinal direction can be highly controlled, a silicone rubber system, particularly a two-liquid addition reaction crosslinking type silicone rubber system, It is desirable to do. In this case, the mold temperature on the raw material inlet side is preferably 100 to 150 ° C. Further, the effect of the temperature difference for reducing the curing time of the elastic layer and making the outer diameter uniform is more favorable. Therefore, 130 to 150 ° C. is more preferable.

  The elastic roller manufactured according to the present invention is extremely excellent in outer diameter accuracy in the longitudinal direction and can be used for various applications. In addition, when used in an electrophotographic image forming apparatus, such as a charging roller, a developer carrying roller, a developing roller, and a static eliminating roller that require electrical conductivity, a conductive material such as conductive carbon is used as an elastic layer material. It should be included. The elastic roller of the present invention is preferable for applications that require a very uniform contact with the photosensitive member and a developer carrying amount, such as a developer carrying roller.

  The elastic roller manufactured by the present invention may be further provided with one or more coating layers for imparting various functions to the outer periphery of the elastic layer. In addition, it is preferable that this coating layer is formed with resin which has a urethane bond, for example, urethane resin.

  The preferred embodiment will now be described in detail for each individual component.

  The metal core 1 used in the present invention is, for example, a cylinder in which a surface of a carbon steel alloy is subjected to chemical nickel plating with a thickness of about 5 μm. When the elastic roller is a conductive elastic roller, it is necessary that at least the surface of the metal core is conductive. In this case, the metal core itself is preferably conductive, but not all It is not necessary to be a conductive metal, and examples of its constituent materials include fibers and powders of metals such as iron, aluminum, titanium, copper and nickel, fibers and powders of alloys such as stainless steel, duralumin, brass and bronze, and It is also possible to use a known material that exhibits rigidity and conductivity, such as a composite material obtained by solidifying carbon black or carbon fiber with plastic, or a material in which a metal conductive layer is provided on the surface of a rigid cylinder made of plastic. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity besides the column shape.

  As the elastic layer material, any material can be used as long as it is a thermosetting rubber material. As described above, silicone rubber is preferable.

  Silicone rubber is excellent in processability, has no dimensional stability due to the generation of by-products associated with the curing reaction, and has an addition reaction cross-linking type for reasons such as stable physical properties after curing. Silicone rubber is preferred.

  This silicone rubber contains, for example, an organopolysiloxane represented by Formula 1 and an organohydrogenpolysiloxane represented by Formula 2, and can be used by being appropriately mixed with a catalyst and other additives.

式中、Rはアルケニル基であり、ｘは正の整数である。

In the formula, R is an alkenyl group, and x is a positive integer.

式中、ｙは２以上の正の整数であり、ｚは正の整数である。

In the formula, y is a positive integer of 2 or more, and z is a positive integer.

  The organopolysiloxane represented by the formula (1) is a base polymer of a silicone rubber raw material, and the molecular weight thereof is not particularly limited, but is preferably 100,000 to 1,000,000, and the average molecular weight is preferably 400,000 to 700,000. Furthermore, from the viewpoint of processing characteristics and the properties of the resulting silicone rubber composition, the lower limit of the viscosity (23 ° C.) of the organopolysiloxane is 10 Pa · s, preferably 50 Pa · s, and the upper limit is 300 Pa · s, preferably Is 250 Pa · s.

  The alkenyl group in the formula (1) is a site that reacts with the active hydrogen of the organohydrogenpolysiloxane represented by the formula (2) to form a crosslinking point, and is not particularly limited. From the viewpoint of high properties, a vinyl group or an allyl group is preferable, and a vinyl group is particularly preferable.

  The organohydrogenpolysiloxane represented by the formula (2) serves as a crosslinking agent for addition reaction in the curing process, and the number of silicon-bonded hydrogen atoms in one molecule is 2 or more, and the curing reaction For optimal performance, 3 or more polymers are preferred. The molecular weight of the polyorganohydrogenpolysiloxane is not particularly limited and is 1000 to 10,000, but a relatively low molecular weight of 1000 to 5000 is preferable in order to appropriately perform the curing reaction.

As the crosslinking catalyst for forming the silicone rubber, for example, chloroplatinic acid hexahydrate can be used, and other transition metal compounds exhibiting a catalytic action in the hydrosilylation reaction can also be used. Examples thereof include Fe (CO) ₅ , Co (CO) ₈ , RuCl ₃ , IrCl ₃ , [(olefin) PtCl ₂ ] ₂ , vinyl group-containing polysiloxane-Pt complex, L ₂ Ni (olefin), L _4. Pd, L ₄ Pt, L ₂ NiCl ₂ (wherein L is PPh ₃ or PR ′ ₃ , P is phosphorus, Ph is a phenyl group, and R ′ is an alkyl group). Among these, platinum, palladium, and rhodium-based transition metal compound catalysts are preferable.

  For example, when a platinum-based metal compound catalyst is used, the blending amount of the catalyst is preferably 1 to 100 ppm as platinum in the liquid silicone rubber raw material (including various blends), but is not limited to this range. It is appropriately selected depending on the target pot life, curing time, product shape and the like.

  Further, the liquid silicone rubber material can contain an unsaturated alcohol such as 1-ethynyl-1-cyclohexanol or phenylbutynol as a curing reaction retarder. The blending amount of the curing reaction retarder is appropriately selected depending on the target pot life, curing time, and product shape in the range of 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the liquid silicone rubber material. .

  Various compounding agents usually used for liquid silicone rubber raw materials can be added within a range that does not impair the characteristics of the low hardness and low compression set of the cured product.

  For example, natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, (meth) acrylonitrile butadiene rubber, ethylene propylene rubber, ethylene propylene diene rubber, butyl rubber, halogenated butyl rubber, silicone rubber, fluorine Examples thereof include rubber, urethane rubber, ethylene vinyl acetate copolymer, ethylene- (meth) acrylate rubber, and epichlorohydrin rubber.

  Examples of the plasticizer that can be included in the liquid silicone rubber raw material include polydimethylsiloxane oil, diphenylsilanediol, trimethylsilanol, phthalic acid derivative, adipic acid derivative, and the like. Examples of the softener include lubricating oil, Process oil, coal tar, castor oil and the like can be mentioned, and as the anti-aging agent, for example, phenylenediamines, phosphates, quinolines, cresols, phenols, dithiocarbamate metal salts and the like are useful, As the heat-resistant agent, for example, iron oxide, cerium oxide, potassium hydroxide, iron naphthenate, potassium naphthenate and the like can be used, and other processing aids, colorants, ultraviolet absorbers, flame retardants, oil resistance improvers. Further, a foaming agent, a scorch inhibitor, a tackifier, a lubricant and the like can be added.

  Examples of fillers (reinforcing fillers and extenders) that can be included in the liquid silicone rubber raw material include fumed silica, wet silica, quartz fine powder, diatomaceous earth, carbon black, zinc oxide, basic magnesium carbonate, activated carbon. Calcium acid, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, glass fiber, carbon black for rubber, organic reinforcing agent, organic filler and the like. The surface of these fillers is preferably hydrophobized by treatment with an organosilicon compound, such as polydiorganosiloxane, to increase dispersibility in the liquid silicone rubber raw material.

  In addition, when the elastic roller manufactured by this invention is an electroconductive elastic roller, a electrically conductive agent is mix | blended with a silicone rubber raw material. Examples of the conductive agent include metal powders and fibers such as aluminum, palladium, iron, copper, and silver; metal oxide powders such as titanium oxide, tin oxide, and zinc oxide; metal compounds such as copper sulfide and zinc sulfide. Powder: Electroless treatment of the surface of non-conductive particles, tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, rhodium, spray coating Examples thereof include powders adhered by work and mixed shaking; conductive carbon powders such as acetylene black, ketjen black, PAN-based carbon black, and pitch-based carbon black.

  Among them, carbon black is particularly preferable because the electrical resistivity can be lowered by adding a relatively small amount, and conductivity can be imparted without increasing the hardness of the elastic layer.

  The viscosity of the elastic layer raw material obtained by adding various additives to the silicone rubber raw material is not particularly limited, but it is 10 Pa · s from the viewpoint of suppressing fluidity to some extent upon injection into the mold and preventing raw material leakage. The above is preferable, and 300 Pa · s or less is preferable from the viewpoint of avoiding the problem of molding processability such as generation of welds between the injection gates.

  A vulcanized adhesion type silicone rubber primer was applied very thinly on the surface of a cylindrical mold as shown in FIG. 2 in which the inner diameter was appropriately selected with respect to the required outer diameter of the elastic layer. A cylindrical injection port in which a metal core is pressed and arranged at both ends, and an elastic layer raw material in which carbon black or the like is blended with the silicone rubber raw material, for example, as a conductive filler is appropriately provided with a temperature difference in the longitudinal direction from one side To obtain a material in which a cored bar and an elastic layer are arranged on its outer periphery in a mold by heating and curing at a temperature of 100 to 150 ° C. for 3 to 60 minutes as primary curing. it can. In addition, it is preferable that the temperature difference in the longitudinal direction is maintained in the mold during the raw material injection and the heat curing. In this case, the primary curing means that the elastic layer material is cured to such an extent that the shape of the elastic layer can be taken out from the mold without remarkably damaging, and further, the elastic layer does not break due to curing in the mold. It refers to curing rubber in the range. Thereafter, the mold is cooled from the outside, and further removed to obtain an elastic roller having an elastic layer with a thickness of 2 to 5 mm. Thereafter, it is also preferable to perform curing and aging in a thermostatic chamber as necessary.

  The cylindrical inner diameter of the mold used here is set in consideration of shrinkage after molding. Further, the temperature difference in the longitudinal direction of the mold during the raw material injection and the subsequent heat curing varies depending on the thickness of the elastic layer, but is usually 3 to 20 ° C, preferably 5 to 15 ° C. If this temperature difference is too large, insufficient curing may occur on the outlet side, or rapid curing may occur on the injection side, and the raw material may not be successfully injected into the mold. On the other hand, if it is too small, the effect of the present invention may not be achieved. Therefore, it is desirable that the temperature difference in the longitudinal direction of the mold is as described above.

  When the elastic roller manufactured by the present invention is measured by the outer diameter measuring method shown in FIG. 3 (described later), the maximum measured value at two places 20 mm from the end of the roller and at three places in the center of the roller is the maximum. The smallest difference is below submicron.

  The elastic roller manufactured by the present invention has sufficient surface accuracy and can be used for various purposes as it is. However, when it is used as a developer carrying roller, various functions are provided on the outer periphery of the elastic layer. A coating layer to be applied can be provided.

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

  These materials constituting the coating layer are dispersed using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, a pearl mill or the like. The obtained dispersion for forming a coating layer is applied to the surface of the conductive elastic layer by a spray coating method, a dipping method, or the like.

  The thickness of the coating layer is preferably 3 μm or more from the viewpoint of preventing a low molecular weight component from seeping out and contaminating a contacted member such as a photoreceptor, and the elastic roller becomes hard and fusion occurs. From the viewpoint of prevention, it is preferably 500 μm or less. More preferably, it is 5-30 micrometers.

  When the elastic roller is a developer carrying roller, fine particles having an average particle diameter of 1 to 20 μm are dispersed in the coating layer formed as described above, thereby facilitating the conveyance of the developer on the roller surface. This is preferable because a sufficient amount of developer can be conveyed to the development area. Examples of the fine particles used for such purpose include plastic pigments such as polymethyl methyl methacrylate fine particles, silicone rubber fine particles, polyurethane fine particles, polystyrene fine particles, amino resin fine particles, and phenol resin fine particles. Methyl acid fine particles and silicone rubber fine particles are preferable. The addition amount of these fine particles is preferably in the range of about 20 to 200% by mass with respect to the total mass of the constituent components of the coating layer excluding the fine particles.

  FIG. 4 shows an example of a schematic diagram of a contact developing type electrophotographic image forming apparatus incorporated as a developer carrying roller having the elastic roller of the present invention.

  Photosensitive drum 31 that is an image forming body, primary charging roller 32, developer carrying roller 33, developer supply roller 34, toner layer thickness regulating member 35 that is a developer layer thickness regulating member, stirring blade 36, and developer. The toner 37 is collected in one cartridge, and is a cartridge that can be integrally replaced in the electrophotographic apparatus.

  The photosensitive drum 31 uniformly charged by the primary charging roller 32 rotates in the direction of the arrow, and a laser beam 40 on which recording information is placed on the surface between the primary charging roller 32 and the developer supply roller 33 is emitted. Irradiation forms a latent image. On the other hand, the toner 37 sent to the developer supply roller 34 by the stirring blade 36 is uniformly coated on the surface of the developer carrying roller 33 by the toner layer thickness regulating member 35 and is carried to the surface of the photoconductor drum 31 to be photoconductor. The latent image formed on the surface of the drum 31 is visualized as a toner image. When the photosensitive drum 31 further rotates and the toner image reaches the transfer region, the toner image is transferred onto a recording medium 43 such as paper by a transfer roller 42 that is opposed to the photosensitive drum 31. The surface of the photosensitive drum 31 is uniformly charged again by the primary charging roller 32 after the toner remaining without being transferred to the recording medium 43 is removed by the cleaning elastic member 38.

  The unfixed toner image transferred to the recording medium 43 passes between the fixing roller 44 and the pressure roller 45, is fixed to the recording medium by pressure and heat, and is discharged from the electrophotographic apparatus.

  On the other hand, the toner remaining on the surface of the developer carrying roller 31 without being used for development is returned to the developing container 41 while being carried on the surface. Inside the developer container 41, the developer supply roller 34 removes toner remaining on the surface of the developer carrying roller 33 from the surface of the developer carrying roller 33 and supplies new toner to the surface of the developer carrying roller 33. The new toner supplied to the surface of the developer carrying roller 33 is uniformly adjusted in the thickness of the toner coated by the toner layer thickness regulating member 35 and is transported to the development area. By repeating this, the developer carrying roller 33 always coats new toner uniformly to develop the electrostatic latent image.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, these do not limit this invention at all.

[Outer diameter measurement method]
As shown in FIG. 3, the elastic roller 11 is inserted between the laser beam transmitter 12 and the laser beam receiver 13 of the laser length measuring device (manufactured by Keyence Corporation, model: LS-5040) 10 to rotate the elastic roller 11. Rotate at a speed of 120 ° / s, and measure the outer diameter at 0.33 ms intervals (every rotation angle of 3.6 °). Thereafter, the measured values for one rotation of the roller (100 pieces) are averaged, and the average value is set as the roller outer diameter at the position. In addition, the outer diameter measuring points in the longitudinal direction are two places 20 mm from the end of the elastic layer of the roller and a total of three places in the center. The difference between the maximum and minimum measured values at each measurement point was defined as the outer diameter difference of the roller.

[Mold temperature setting]
Thermocouples were attached to both ends and the center of the cylindrical mold, set on the hot platen of the injection apparatus, and the temperature of each part was measured immediately before the raw material was injected. Immediately after the raw material injection, the mold temperature decreased, but thereafter, the temperature was adjusted to the temperature of each part that was temperature-controlled before material injection, and the temperature was adjusted at that temperature until the mold was removed from the hot platen.

(Image density measurement)
The developer carrying roller is incorporated as an electrophotographic image forming apparatus (A4 size output machine, recording medium output speed is A4 vertical 16 sheets / min, image resolution is 600 dpi), room temperature, 80% After 1 week at RH, 100 solid black images are output continuously with standard output, and the central part of the last black image and the two ends of the A4 lateral direction are combined into three Macbeth densitometers ( The image density was measured by Sakata Inx Co., Ltd. (RD-918), and among the measured values, the difference between the maximum and the minimum was taken as the difference between the left and right image densities of the roller.

Example 1
A mold as shown in FIG. 2 was used. An inner surface of a stainless steel cylinder having an inner diameter of 12.4 mm and a mirror-finished inner surface was used as a cylindrical mold. Moreover, the same shape was used for the piece which can hold | maintain a metal core in a metal mold | die. The cored bar was prepared by applying a vulcanized adhesion type silicone rubber primer to a thickness of 10 μm on a 6 mm diameter iron bar surface formed by chemical plating with a 5 μm thick nickel layer. The mold was set at the raw material outlet side of 124.6 ° C., the temperature was adjusted to the raw material injection side of 130 ° C., and the raw material was injected at a constant rate over 20 seconds. Thereafter, each part of the mold was heated for 5 minutes while adjusting the temperature at the same temperature as when the raw material was injected to cure the silicone rubber raw material to obtain a conductive elastic roller having an outer diameter of about 12 mm and a rubber part length of 240 mm. The outer diameter of the obtained conductive elastic roller was measured by the above method, and the image density was also measured. The results are summarized in Table 1.

  The material used for forming the elastic layer was obtained from a silicone rubber manufacturer using a raw material appropriately mixed with organopolysiloxane, organohydrogenpolysiloxane, conductive carbon, platinum catalyst, quartz and silica.

Example 2
The outer diameter was the same as in Example 1 except that a mold with an inner diameter of 16.5 mm was used, the core metal had a diameter of 8 mm, and the mold temperature was 122.4 ° C. on the outlet side and 130 ° C. on the injection side. A conductive elastic roller of about 16 mm was obtained. Measurements were performed in the same manner as in Example 1, and the results are summarized in Table 1.

Example 3
In Example 2, a conductive elastic roller was obtained in the same manner as in Example 2 except that the mold temperature was 137.7 ° C. on the outlet side and 150 ° C. on the injection side. Measurements were performed in the same manner as in Example 2, and the results are summarized in Table 1.

Comparative Example 1
In Example 1, a conductive elastic roller was obtained in the same manner as in Example 1 except that the temperature of the mold was set to 130 ° C. on the outlet side. Measurements were performed in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 2
In Example 2, a conductive elastic roller was obtained in the same manner as in Example 2 except that the temperature of the mold was set to 130 ° C. on the outlet side. Measurements were performed in the same manner as in Example 2, and the results are summarized in Table 1.

Comparative Example 3
In Example 3, a conductive elastic roller was obtained in the same manner as in Example 3 except that the temperature of the mold was 150 ° C. on the outlet side. Measurements were performed in the same manner as in Example 3, and the results are summarized in Table 1.

It is sectional drawing of an example of the elastic roller of this invention. It is a schematic cross section of the shaping | molding die for shaping | molding of the elastic roller of this invention. It is a figure explaining the outer diameter measuring method of the elastic roller of the present invention. It is a figure explaining the electrophotographic image forming apparatus incorporating the elastic roller of this invention as a developer carrying | support roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core metal 2 Elastic layer 3 Elastic layer formation cavity 4 Piece 4a Raw material supply path 5 Piece 5a Exhaust passage 6 Pipe-shaped metal mold 11 Elastic roller 12 Laser beam transmitter 13 Laser beam receiver 31 Photosensitive drum 32 Primary charging roller 33 Developer carrying roller 34 Developer supply roller 35 Toner layer thickness regulating member 36 Stirring blade 37 Toner 38 Cleaning elastic member 40 Laser beam 41 Developer container 42 Transfer roller 43 Recording medium 44 Fixing roller 45 Pressure roller

Claims (6)

  When producing an elastic roller having a thermosetting elastic layer on the outer periphery of the core metal by injecting a thermosetting elastic layer raw material from one end of a cylindrical molding die provided with a core metal, followed by heat curing. A method for producing an elastic roller, characterized in that the temperature of the cylindrical mold is lower on the opposite side (outlet side) than on the raw material injection side during the raw material injection and heat curing.   The method for producing an elastic roller according to claim 1, wherein the thermosetting elastic layer material is an addition reaction cross-linkable liquid silicone rubber.   The method for producing an elastic roller according to claim 1, wherein the elastic layer has conductivity.   The method for producing an elastic roller according to claim 3, wherein the elastic roller is a developer carrying roller.   An electrophotographic process cartridge comprising an elastic roller manufactured by the manufacturing method according to claim 4 as a developer carrying roller.   An image forming apparatus, wherein an elastic roller manufactured by the manufacturing method according to claim 4 is incorporated as a developer carrying roller.

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