JP2010076205A - Method of manufacturing conductive roller, conductive roller, charged roller, and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller, which can solve a current-carrying deterioration in the conductive roller in a high-temperature and high-humidity environment (for example, 30°C and a relative humidity of 80%) under high current-carrying conditions (for example, a DC current of 0.2 mA or more and an AC current of 2 mA or more). <P>SOLUTION: The conductive roller is manufactured by forming on a support an unvulcanized rubber layer having a layer of inorganic particles on the surface, vulcanizing the unvulcanized rubber while changing so as to push a die-pushing position to the whole layer of the inorganic particles at fixed distances as pushing the die to the inorganic particle layer, and forming the rubber layer in which the inorganic particles are embedded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a conductive roller mainly used in an electrophotographic apparatus, a conductive roller manufactured by the manufacturing method, and an electrophotographic apparatus having the conductive roller.

  2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, an image forming unit is installed inside a main body, and an image is formed through cleaning, charging, latent image, development, transfer, and fixing processes. The image forming unit includes a photosensitive drum that is an electrophotographic photosensitive member, and includes a cleaning unit, a charging unit, a latent image forming unit, a developing unit, and a transfer unit. The image on the photosensitive drum formed by the image forming unit is transferred to the recording material at the transfer unit, and after being transported to the fixing unit, heated and pressed by the fixing unit to be fixed on the recording material. Is output.

  Next, the charging, latent image formation, development, and transfer processes in the cleaning, charging, latent image, development, transfer, and fixing processes will be described.

  In the charging unit, the charging member performs primary charging with a predetermined polarity on the surface of the photosensitive drum so that the potential is uniform. Next, by receiving exposure of target image information, an electrostatic latent image corresponding to the target image is formed on the surface of the photosensitive drum. The electrostatic latent image is visualized as a toner image by a developing member or a developer at the developing unit. The visualized toner image is transferred from the surface of the photosensitive drum to the recording material by the transfer member at the transfer portion. The transferred unfixed toner image is conveyed to a fixing unit, fixed by the fixing unit, and output as a recorded image.

  There are a corona charging method and a roller charging method as charging methods used in the electrophotographic apparatus. The corona charging method is a charging method in which a voltage is applied to a corona wire to form a charged product, and the surface of the photosensitive drum is charged with the charged product. On the other hand, the roller charging method is a charging method in which the surface of the photosensitive drum is charged by discharging by bringing the charging roller into contact with or close to the photosensitive drum (the distance between the roller drums is close to several tens μm but not in contact).

  The roller charging method has an extremely small amount of ozone and discharge products generated compared to the corona charging method. Therefore, by using roller charging, it is possible to reduce the space for attaching the ozone filter, and to reduce image blurring caused by discharge products.

  The roller charging method is divided into AC + DC charging in which alternating current (AC) is superimposed on direct current (DC), and DC charging only in DC. While DC charging is a suitable technique for achieving downsizing and low cost, the charging bias area that keeps the photoreceptor drum potential constant is narrow, roller resistance circumferential unevenness, minute resistance unevenness due to dirt, and roller unevenness There are technical problems such as non-uniform charging due to the property. It is AC + DC charging that compensates for such technical problems and improves the maintenance of image quality. However, since AC is superimposed, there is a problem that charging noise is generated, the amount of discharge current is larger than DC charging, and image blur occurs depending on conditions.

  Further, as a problem in roller charging, there is energization deterioration. The deterioration of energization is a phenomenon in which a desired drum potential cannot be applied due to a change in electrical resistance caused by passing a current through a roller. Generally, energization deterioration is a phenomenon in which the drum potential decreases due to an increase in electrical resistance.

  In recent years, an electrophotographic apparatus is required to have high image quality and a long life. As an approach from the electrophotographic photosensitive member to satisfy the high image quality, there is a method of increasing the electrostatic capacitance of the electrophotographic photosensitive member by thinning the electrophotographic photosensitive member to make the contrast of the latent image clearer. In addition, use of an electrophotographic photoreceptor corresponding to a short-wavelength laser (particularly 380 to 500 nm) may also be mentioned. Further, as an approach from the electrophotographic photosensitive member for satisfying the long life, a method using an amorphous silicon photosensitive member, a method of providing a surface protective layer for protecting the photosensitive layer, and the like can be mentioned.

  When a roller charging method is employed in an electrophotographic process using an amorphous silicon photoreceptor or a thin film photoreceptor, a large current is required for charging because the electrostatic capacity of the photoreceptor is large. Accordingly, a large current flows through the charging roller, and the charging roller is increased in resistance (energization deterioration). In particular, in a high temperature and high humidity environment (for example, 30 ° C. and relative humidity 80%), the energization deterioration becomes more severe. As a result of studying the mechanism of deterioration of energization in a high temperature and high humidity environment, it has been found that the cause is oxidative deterioration of the surface of the charging roller. That is, when the large current is applied, the surface of the charging roller is oxidized and deteriorated by the discharge and moisture generated between the surface of the charging roller and the surface of the photosensitive drum, and the resistance is increased.

  As a prior art that suppresses oxidative deterioration of a charging roller to improve current deterioration, Patent Document 1 is an invention of an electrophotographic conductive member containing an antioxidant having a specific chemical structural formula. It is a technology that suppresses deterioration of energization by capturing radicals generated during energization with an antioxidant.

  Patent Documents 2 and 3 are inventions related to a conductive material containing an ionic conductive material having a specific chemical structural formula in a polar polymer such as hydrin rubber. It is a technology that suppresses deterioration of energization by using an ionic conductive material that is less likely to bleed and is less susceptible to deterioration of energization.

  Patent Documents 4, 5, and 6 report an invention that solves various problems such as prevention of contamination and sticking of the charging roller by adhering powder (inorganic particles, insulating layered compound, toner) to the surface of the charging roller. Has been.

Patent Document 7, Patent Document 8, and Patent Document 9 report an invention that solves various problems such as charging uniformity by including inorganic particles in the coating layer of the charging roller.
JP 2006-47560 A JP 2001-273815 A JP 2004-258277 A JP 09-179375 A JP 2005-338168 A JP 2006-301107 A Japanese Patent Laid-Open No. 08-262843 JP 2003-316110 A Japanese Patent Laid-Open No. 2004-004146

  The method described in Patent Document 1 is also effective, but in an electrophotographic process that requires a large current, the progress of oxidation deterioration near the surface is faster than the deterioration inside the charging roller, and the effect of the antioxidant is exhibited. Not.

  In addition, when the ion conductive materials described in Patent Documents 2 and 3 are used, in an electrophotographic process that requires a large current, current deterioration occurs in a low-humidity environment, and bleeding occurs in a high-humidity environment. There is a harmful effect that occurs. Since this is due to the molecular mobility of the polar polymer, even if the chemical structural formula of the ion conductive material is specified, there is no effect on the current deterioration.

  The inventions described in Patent Documents 4, 5 and 6 are effective means in that the occurrence of oxidative deterioration on the surface can be suppressed, but the progress of oxidative deterioration to the inside cannot be suppressed. Therefore, the effect on energization deterioration in a high temperature and high humidity environment under a large current energizing condition is small.

  The inventions described in Patent Documents 7, 8, and 9 are also effective means. However, in the present invention, since it is dispersed throughout the coating layer and does not localize on the surface, the effect on the energization deterioration in a high-temperature, high-humidity environment under a large current energization condition is small.

  An object of the present invention is to solve the deterioration of energization of a charging roller in a high-temperature and high-humidity environment (for example, 30 ° C. and a relative humidity of 80%) under a large current energizing condition (for example, a DC current of 0.2 mA or more and an AC current of 2 mA or more). And

  As a result of inventing a conductive roller with an inorganic particle layer locally formed in the vicinity of the surface and actually using it as a charging roller, it has been found that the deterioration of energization of the charging roller in a high-temperature, high-humidity environment can be solved under a large current energizing condition. It was. Invented a method of manufacturing a conductive roller for locally forming an inorganic particle layer near the surface.

The first conductive roller manufacturing method according to the present invention is:
(I) forming a conductive unvulcanized rubber layer on the support;
(Ii) forming an inorganic particle layer on the surface of the unvulcanized rubber layer;
(Iii) While pressing the mold against the surface of the inorganic particle layer, the unvulcanized rubber is added while changing the pressing position of the mold against the entire inorganic particle layer at regular intervals. Vulcanizing and forming a rubber layer embedded with the inorganic particles;
Is a method of manufacturing a conductive roller having

Moreover, the second method for producing a conductive roller according to the present invention is as follows.
(I) forming a conductive unvulcanized rubber layer on the support;
(Ii) While pressing the mold against the surface of the unvulcanized rubber layer, the pressing position of the mold is changed so as to press the entire unvulcanized rubber layer at regular intervals, Supplying inorganic particles to the surface of the mold in a region not pressed against the vulcanized rubber layer and vulcanizing the unvulcanized rubber to form a rubber layer embedded with the inorganic particles;
Is a method of manufacturing a conductive roller having

  An electrophotographic apparatus according to the present invention is an electrophotographic apparatus using the conductive roller manufactured by the above-described conductive roller manufacturing method as a charging roller.

  According to the conductive roller of the present invention, the particle layer embedded in the surface serves as a layer for preventing oxidative deterioration of the conductive rubber caused by discharge and moisture. As a result, in an electrophotographic process (a process for mounting an amorphous silicon photoconductor and a thin film OPC) that requires a high-current energization condition, it becomes a means for solving energization deterioration that is a problem in a high-temperature and high-humidity environment.

(First conductive roller manufacturing method)
In order to form the inorganic particle layer on the surface of the conductive roller,
(I) a step of forming a conductive unvulcanized rubber layer on the support (ii) a step of forming an inorganic particle layer on the surface of the unvulcanized rubber layer (iii) the inorganic particle layer; While pressing the mold against the surface, the unvulcanized rubber is vulcanized by embedding the inorganic particles while changing the pressing position of the mold to press the entire layer of the inorganic particles at regular intervals. Forming a rubber layer.

  The process of forming a conductive unvulcanized rubber layer on the support, which is a process of the present invention, will be described. An unvulcanized rubber layer can be coated on a support by extruding an unvulcanized rubber prepared by blending a polymer raw material and an additive together with the support together with the support. However, this step is not limited to this method. For example, a support body that is coated with an unvulcanized rubber layer is prepared by inserting the support body after forming an unvulcanized rubber layer into a cylindrical shape. May be. FIG. 1 is an example of an explanatory view schematically showing the step (i). The extruder 1 includes a cross head 2. In the cross head 2, a support body fed by a cored bar feed roller 3 rotating in the direction of the arrow is inserted from behind, and a cylindrical unvulcanized rubber layer is integrally extruded simultaneously with the support body. A support whose periphery is coated with an unvulcanized rubber layer is obtained. Here, the end portion of the unvulcanized rubber layer around the obtained support was cut out with a standard length to obtain an unvulcanized rubber roller 4. The support used in the present invention may be any material as long as it is rigid, and examples thereof include metals such as aluminum, iron, and SUS, engineering plastics, and carbon composite materials. For a member that charges a photosensitive member by applying a voltage from a support like a charging roller, SUS is desirable from the viewpoint of rigidity, conductivity, and moldability.

Examples of the polymer raw material used in the present invention include the following. Natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, silicone rubber, urethane rubber, fluorine rubber, chlorine Rubber etc. Considering the effect on energization deterioration in a high-temperature and high-humidity environment under a large current energizing condition, acrylonitrile butadiene rubber (NBR) and styrene butadiene rubber (SBR) are more preferable. Examples of the additive used in the present invention include a conductive agent, a vulcanizing agent, and a vulcanization accelerator. Examples of the conductive agent include carbon black, graphite, CNT, conductive metal oxide (oxygen deficient type), ITO, antimony-doped tin oxide, ammonium salt-based ionic conductive agent, ionic liquid, and the like. Considering the effect on energization deterioration in a high-temperature and high-humidity environment under a large current energizing condition, at least one carbon black selected from the following (1) to (3) is preferable.
(1) Carbon black with low BET (nitrogen adsorption specific surface area) and low DBP (dibutyl phthalate) oil absorption,
(2) Carbon black with small BET (nitrogen adsorption specific surface area) and large DBP (dibutyl phthalate) oil absorption,
(3) Carbon black with a large BET (nitrogen adsorption specific surface area) and a large DBP (dibutyl phthalate) oil absorption.

  Examples of the vulcanizing agent and vulcanization accelerator include sulfur, thiazole series, thiuram series, and dithiocarbamine hydrochloride series. In addition, fillers, plasticizers, etc. may be added as appropriate.

  Next, the step of forming the inorganic particle layer on the surface of the unvulcanized rubber layer, which is the step of the present invention, will be described. FIG. 2 is an example of an explanatory view schematically showing the step (ii). The unvulcanized rubber roller 4 is installed on a holding jig 5 that holds and rotates the unvulcanized rubber roller 4 created in the step (i). The powder coating device 6 is installed in a direction perpendicular to the surface of the unvulcanized rubber roller 4. The powder coating device can move horizontally in the longitudinal direction of the unvulcanized rubber roller 4. Examples of the powder coating device 6 include an electrostatic coating device and a spray coating device. When an electrostatic coating device is used, the inorganic particles are electrostatically charged and adsorbed onto the surface of the unvulcanized rubber layer by Coulomb force, so that a layer in which a large number of inorganic particles overlap can be formed. Can be adjusted to a desired thickness. The charged inorganic particles can be held on the surface of the unvulcanized rubber layer. The distance between the surface of the unvulcanized rubber roller 4 and the powder coating device 6, the moving speed of the powder coating device 6, the rotational speed of the unvulcanized rubber roller 4, etc. are set as appropriate so that the powder can be applied uniformly. Set to. By rotating the unvulcanized rubber roller 4 and spraying inorganic particles from the powder coating device 6 and horizontally moving in the longitudinal direction, an unvulcanized rubber roller 7 having a layer of inorganic particles can be obtained.

Inorganic particles include iron oxide, zinc oxide, silver oxide, copper oxide, selenium oxide, carbons, silica (SiO ₂ ), titanium oxide (TiO ₂ ), calcium carbonate (CaCO ₃ ), and strontium titanate (SrTiO ₃ ). Etc. Silica (SiO ₂ ), titanium oxide (TiO ₂ ), and strontium titanate (SrTiO ₃ ) are particularly desirable from the viewpoint of deterioration of energization under high current energization conditions in a high temperature and high humidity environment. These inorganic particles are preferably fine powder particles, and those having a primary particle size of 10 nm to 100 nm can be suitably used. In addition, when these inorganic particles are subjected to a hydrophobizing treatment, the effect of suppressing energization deterioration is further increased. Examples of the hydrophobizing agent include the following. Silane compounds such as trimethylsilane and triethylsilane, silicone oils such as dimethylsilicone and methylhydrogensilicone, fatty acid metal salts such as zinc stearate, aluminum stearate, and aluminum laurate. This is because by performing the hydrophobization treatment, it is possible to suppress the absorption and adsorption of moisture, which is the cause of oxidative degradation.

  Next, a mold is pressed against the surface of the inorganic particle layer, which is the process of the present invention, and the rubber layer in which the inorganic particles are embedded is obtained by vulcanizing the unvulcanized rubber while changing the pressing position of the mold. The process to form is demonstrated. FIG. 3 is an example of an explanatory diagram schematically showing the process. FIG. 3A is a front view, and FIG. 3B is a side view. While pressing the mold against the surface of the powder-coated unvulcanized rubber roller 7 obtained in the step (ii) and changing the position of pressing the mold against the surface of the powder-coated unvulcanized rubber layer, In this step, the unvulcanized rubber is vulcanized, and the vulcanized rubber layer is formed while pressing the inorganic particles on the surface. Here, the mold is a pressure contact member for pressing the inorganic particle layer on the surface of the unvulcanized rubber layer and embedding it inside the unvulcanized rubber layer. Further, when changing the pressing position of the mold, it is desirable to include the entire layer of inorganic particles as a target to be pressed, and pressing the entire layer at a constant interval is equally pressed against the entire layer.

  FIG. 3 is an explanatory view of a pressure vulcanization apparatus having a cylindrical mold (pressure contact member) that is rotatably held and used in the step (iii). The rotating cylindrical pressure contact member 8 and the central axis of the unvulcanized rubber roller 7 are held in parallel, and holding members 9 for pressurization are pressed against the exposed portions of the support at both ends of the unvulcanized rubber roller. The shaft is held so that it does not shift from side to side. The pressure contact member 8 has a built-in heater and is set to a predetermined temperature, or the entire apparatus is maintained in a constant temperature bath to keep the entire temperature at a predetermined temperature, or both may be performed simultaneously. . Further, there may be a difference between the temperature of the pressure contact member and the atmosphere, for example, the temperature of the pressure contact member 8 is set higher than the temperature of the atmosphere. Further, the unvulcanized rubber roller 7 can be driven to rotate by rotating the pressure contact member by the motor 10. A holding member for the support is supported by a rail 11 that is easily movable in the vertical direction, and can follow the change in the outer diameter of the unvulcanized rubber roller 7. Further, the pressure can be adjusted by changing the weight of the weight 12.

  When the unvulcanized rubber layer is thin, the support that supports the unvulcanized rubber composition layer interferes with the pressure contact member due to deformation of the unvulcanized rubber composition layer due to pressurization. Therefore, the thickness of the unvulcanized rubber layer is preferably 0.25 mm or more. Moreover, if the thickness of the layer is 5.0 mm or less by the method of the present invention, it can be produced, but it is not limited to this range. If the viscosity of the unvulcanized rubber layer is too low, the deformation becomes too large at the time of pressure contact, and the unvulcanized rubber roller 7 cannot maintain the cylindrical shape with rotation. Moreover, when the viscosity of the unvulcanized rubber layer becomes too high, the embedding of the inorganic particles becomes insufficient. In such a case, it is possible to appropriately adjust the temperature of the pressure contact member, the atmospheric temperature, the pressure pressure, the material composition of the unvulcanized rubber layer, and the like. From the above viewpoint, the preferred viscosity of the unvulcanized rubber is preferably adjusted within the range of 10 to 100 ML (1 + 4) 100 ° C. by Mooney viscosity measurement specified in JIS K6300-1.

  Since the pressure contact member 8 is a member for vulcanizing the unvulcanized rubber while pressing the inorganic particles on the surface of the unvulcanized rubber as a mold, metals such as SUS and nickel having good thermal conductivity are preferable. . In order to improve the indentation efficiency of the inorganic particles, the pressure contact member 8 may be subjected to plating such as chrome plating, nickel plating, or fluorine-containing nickel plating. Further, fluorine coating, coating with fluorine resin / silicone resin, or coating with fluorine / silicone release agent may be used. Further, other known metal surface treatments may be used. Particularly desirable is a surface treatment with releasability such as fluorine coating and fluorine resin / silicone resin. By performing the releasable surface treatment, the efficiency of the inorganic particles embedded in the unvulcanized rubber surface is improved, and the probability that the inorganic particles remain on the pressure contact member is reduced. It is preferable to use a member having a width equal to or longer than that of the unvulcanized rubber layer. As a form of the pressure contact member 8, a cylindrical shape, a planar shape, an endless belt shape, or the like is desirable. (The figure is a schematic diagram of a cylindrical shape.) In addition, in order to make the obtained roller member a crown shape or a reverse crown shape having different diameters in the longitudinal direction, a reverse crown shape (the diameter of the central portion is smaller than the diameter of the end portion). May be used), or a pressure contact member having a crown shape (the diameter of the central portion is larger than the diameter of the end portion) may be used. Further, the unvulcanized rubber roller does not need to be continuously pressed and rotated until the end of vulcanization, and may be heated in a hot air furnace or the like without being pressed and rotated as long as particle embedding proceeds.

(Second conductive roller manufacturing method)
Next, in the second conductive roller manufacturing method of the present invention, in order to form an inorganic particle layer on the surface of the conductive roller,
(I) Step of forming a conductive unvulcanized rubber layer on the support (ii) While pressing the mold against the surface of the unvulcanized rubber layer, the pressing locations of the mold are set at regular intervals. An inorganic particle is supplied to the surface of the mold in a region not pressed against the unvulcanized rubber layer while being changed so as to be pressed against the whole unvulcanized rubber layer, and the unvulcanized rubber Is vulcanized to form a rubber layer in which the inorganic particles are embedded.

  The process of forming a conductive unvulcanized rubber layer on the support, which is a process of the present invention, will be described. An unvulcanized rubber layer can be coated on a support by extruding an unvulcanized rubber prepared by blending a polymer raw material and an additive together with the support together with the support. However, this step is not limited to this method. For example, a support body that is coated with an unvulcanized rubber layer is prepared by inserting the support body after forming an unvulcanized rubber layer into a cylindrical shape. May be. FIG. 1 is an example of an explanatory view schematically showing the step (i). The extruder 1 includes a cross head 2. In the cross head 2, a support body fed by a cored bar feed roller 3 rotating in the direction of the arrow is inserted from behind, and a cylindrical unvulcanized rubber layer is integrally extruded simultaneously with the support body. A support whose periphery is coated with an unvulcanized rubber layer is obtained. Here, the end portion of the unvulcanized rubber layer around the obtained support was cut out with a standard length to obtain an unvulcanized rubber roller 4.

  The support used in the present invention may be any material as long as it is rigid, and examples thereof include metals such as aluminum, iron, and SUS, engineering plastics, and carbon composite materials. For a member that charges a photosensitive member by applying a voltage from a support like a charging roller, SUS is desirable from the viewpoint of rigidity, conductivity, and moldability.

  Examples of the polymer raw material used in the present invention include the following. Natural rubber, butadiene rubber, styrene butadiene rubber (SBR), nitrile rubber, ethylene propylene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), epichlorohydrin rubber, butyl rubber, silicone rubber, urethane rubber, fluorine rubber, chlorine Rubber etc. Considering the effect on energization deterioration in a high-temperature and high-humidity environment under a large current energizing condition, acrylonitrile butadiene rubber (NBR) and styrene butadiene rubber (SBR) are more preferable.

Examples of the additive used in the present invention include a conductive agent, a vulcanizing agent, and a vulcanization accelerator. Examples of the conductive agent include carbon black, graphite, CNT, conductive metal oxide (oxygen deficient type), ITO, antimony-doped tin oxide, ammonium salt-based ionic conductive agent, ionic liquid, and the like. Considering the effect on energization deterioration in a high-temperature and high-humidity environment under a large current energizing condition, at least one carbon black selected from the following (1) to (3) is preferably used.
(1) Carbon black with low BET (nitrogen adsorption specific surface area) and low DBP (dibutyl phthalate) oil absorption,
(2) Carbon black with small BET (nitrogen adsorption specific surface area) and large DBP (dibutyl phthalate) oil absorption,
(3) Carbon black with a large BET (nitrogen adsorption specific surface area) and a large DBP (dibutyl phthalate) oil absorption.

  Examples of the vulcanizing agent and vulcanization accelerator include sulfur, thiazole series, thiuram series, and dithiocarbamine hydrochloride series. In addition, fillers, plasticizers, etc. may be added as appropriate.

  Next, while pressing the mold against the surface of the unvulcanized rubber layer, which is the process of the present invention, changing the pressing position of the mold and supplying inorganic particles to the surface of the mold, the unvulcanized A process of vulcanizing rubber to form a rubber layer in which the inorganic particles are embedded will be described. Here, the mold is a pressure contact member for pressing the inorganic particle layer on the surface of the unvulcanized rubber layer and embedding it in the unvulcanized rubber layer, as in the first manufacturing method. In addition, when changing the pressing location of the mold, the entire layer of inorganic particles is included as a target to be pressed, and pressing the entire layer at a constant interval is equally applied to the entire layer. desirable. FIG. 4 is an example of an explanatory view schematically showing the step (ii). FIG. 4A is a front view, and FIG. 4B is a side view. The pressure contact member 8 is pressed as a mold against the surface of the unvulcanized rubber roller 4 created in the step (i). Then, the powder coating device 6 is installed above the pressure contact member 8 so that the powder can be applied to the entire surface of the pressure contact member. In the figure, five powder coating apparatuses are installed, but the number of installed powder coating apparatuses may be arbitrarily set. Further, one powder coating device may be traversed horizontally above the pressure contact member 8. While applying inorganic particles from the powder coating device 6 as described above, the unvulcanized rubber roller 4 is held by the roller holding member 13, pressed against the pressure contact member 8 by the pressure member 14, and the pressure contact member 8 is rotated by the pressure contact member. While rotating with the jig 15, the inorganic particles are embedded in the surface of the unvulcanized rubber layer to form vulcanized rubber. A heater may be installed inside the pressure contact member 8 to embed and vulcanize the inorganic particles. Further, vulcanization may be performed by heating hot air inside the apparatus.

The pressing member 14 is preferably performed by spring pressing. Inorganic particles include iron oxide, zinc oxide, silver oxide, copper oxide, selenium oxide, carbons, silica (SiO ₂ ), titanium oxide (TiO ₂ ), calcium carbonate (CaCO ₃ ), and strontium titanate (SrTiO ₃ ). Etc. Silica (SiO ₂ ), titanium oxide (TiO ₂ ), and strontium titanate (SrTiO ₃ ) are particularly desirable from the viewpoint of deterioration of energization under high current energization conditions in a high temperature and high humidity environment. These inorganic particles are preferably fine powder particles, and those having a primary particle size of 10 nm to 100 nm can be suitably used. In addition, when these inorganic particles are subjected to a hydrophobizing treatment, the effect of suppressing energization deterioration is further increased. Examples of the hydrophobizing agent include the following. Silane compounds such as trimethylsilane and triethylsilane, silicone oils such as dimethylsilicone and methylhydrogensilicone, fatty acid metal salts such as zinc stearate, aluminum stearate, and aluminum laurate. This is because by performing the hydrophobizing treatment, it is possible to suppress water absorption and adsorption of water, which is a cause of oxidative degradation. When the unvulcanized rubber layer is thin, deformation of the unvulcanized rubber composition layer accompanying pressurization may cause interference between the support member that supports the unvulcanized rubber composition layer and the pressure contact member. Therefore, the thickness of the unvulcanized rubber layer is preferably 0.25 mm or more. Moreover, if the thickness of the layer is 5.0 mm or less by the method of the present invention, it can be produced, but it is not limited to this range. If the viscosity of the unvulcanized rubber layer is too low, the deformation becomes too large at the time of pressure contact, and the unvulcanized rubber roller 7 cannot maintain the cylindrical shape with rotation. Moreover, when the viscosity of the unvulcanized rubber layer becomes too high, the embedding of the inorganic particles becomes insufficient. In such a case, it is possible to appropriately adjust the temperature of the pressure contact member, the atmospheric temperature, the pressure pressure, the material composition of the unvulcanized rubber layer, and the like. From the above viewpoint, the preferred viscosity of the unvulcanized rubber is preferably adjusted within the range of 10 to 100 ML (1 + 4) 100 ° C. by Mooney viscosity measurement described in JIS K6300-1.

  Since the pressure contact member 8 is a member for vulcanizing the unvulcanized rubber while pressing the inorganic particles on the surface of the unvulcanized rubber as a mold, metals such as SUS and nickel having good thermal conductivity are preferable. .

  In addition, in order to improve the indentation efficiency of inorganic particles, the pressure contact member 8 is coated with fluorine coating, fluorine resin / silicone resin, etc. in addition to chrome plating, nickel plating, fluorine-containing nickel plating, etc. Can be used. Moreover, you may use what apply | coated the mold release agent of the fluorine type and silicone type, and the surface treatment of other well-known metals. Particularly desirable is a surface treatment with releasability such as fluorine coating and fluorine resin / silicone resin. By performing the releasable surface treatment, the efficiency of the inorganic particles embedded in the unvulcanized rubber surface is improved, and the probability that the inorganic particles remain on the pressure contact member is reduced. It is preferable to use a member having a width equal to or longer than that of the unvulcanized rubber layer. The form of the pressure contact member 8 is preferably a cylindrical shape, a planar shape, an endless belt shape, or the like (the figure is a schematic diagram of a cylindrical shape). Moreover, in order to make the obtained roller member into a crown shape or a reverse crown shape having different diameters in the longitudinal direction, a reverse crown shape (the diameter of the central portion is smaller than the diameter of the end portion) or a crown shape (the diameter of the central portion) The pressure contact member may be larger than the diameter of the end portion. Further, the unvulcanized rubber roller does not need to be continuously pressed and rotated until the end of vulcanization, and may be heated in a hot air furnace or the like without being pressed and rotated as long as particle embedding proceeds.

  The second production method of the present invention can not only reduce the number of production steps, but also control the supply amount of particles embedded in the surface, so that the layer of inorganic particles can be formed. There is an advantage that the layer thickness can be arbitrarily changed.

In the first and second production methods, it is preferable to vulcanize the unvulcanized rubber after controlling the temperature of the mold to advance the embedding of the inorganic particles. Specifically, the initial temperature of the pressure contact member is controlled to a temperature at which vulcanization does not proceed, for example, 80 ° C. to 120 ° C., and pressure contact is performed for a predetermined time to promote embedding of inorganic particles. The reason for pressure welding at such a temperature is that the viscosity of the unvulcanized rubber is lowered by heat and the inorganic particles can be embedded more uniformly. Thereafter, in order to advance vulcanization, the temperature of the pressure contact member is controlled to a temperature at which vulcanization proceeds, for example, 140 ° C to 220 ° C. Through such a process, the embedded inorganic particles can be fixed inside the rubber. Further, the vulcanization start temperature depends on the formulation of the vulcanizing agent and the vulcanization accelerator. Sulfur is preferred for the vulcanizing agent, and sulfur vulcanizing accelerator is preferred for the vulcanization accelerator. With regard to the vulcanization accelerator, it is preferable to use one or more sulfur vulcanization accelerators such as thiazole, thiuram, dithiocarbamic acid, thiourea, guanidine, and sulfanamide. It is desirable to clarify the boundary line between the temperature at which vulcanization does not proceed and the temperature at which vulcanization proceeds by combining the types of vulcanizing agents and vulcanization accelerators and their blending amounts. As an index for that purpose, there are scorch time of unvulcanized rubber described in JIS K6300-1, measurement of vulcanization curve of unvulcanized rubber described in JIS K6300-2, and the like. For example, an unvulcanized rubber having a scorch time t _{5 at} 100 ° C. of 20 (min) or more and a vulcanization curve t _C (50) at 160 ° C. of 15 min or less is produced by changing the mold temperature stepwise. Preferred formulation for the method.

(Conductive roller)
Next, the conductive roller obtained by the production method of the present invention will be described. FIG. 5 is a schematic view of a conductive roller obtained by the above-described manufacturing method. On the surface of the rubber layer of the conductive roller, inorganic particles are embedded to form a layer. Being embedded means that, unlike adhesion, the inorganic particles reach the inside of the rubber layer and form a layer having a thickness. The layer thickness of the inorganic particle layer can be measured by a cross-sectional observation technique such as SEM or TEM, or a surface element analysis technique such as ESCA or EDX. If the layer thickness of the inorganic particles is within 10 μm, the conductivity of the conductive roller is affected but small. If it exceeds 10 μm, the resistance of the conductive roller becomes high, and it cannot be applied to applications where conductivity is essential (for example, a charging roller, a developing roller, a transfer roller). From the viewpoint of deterioration of energization in a high-temperature and high-humidity environment under a large current energizing condition, the layer thickness of the inorganic particles is preferably 30 nm or more. More preferably, it is 50 nm or more and 1000 nm or less.

  The effect of the layer of inorganic particles embedded in the surface on the deterioration due to energization will be described. Inorganic particles do not undergo oxidative degradation due to electric discharge, and even if organic substances and discharge products attached to the surface undergo oxidative degradation and generate active radicals, the inorganic particle layer prevents oxidative degradation from proceeding inside. To work. That is, the inorganic particle layer serves as a layer for preventing discharge deterioration on the surface of the charging roller, and can improve the deterioration of energization in a high-temperature and high-humidity environment under a large current energization condition. In addition, by applying hydrophobic treatment to the inorganic particles, the amount of organic substances and discharge products adhering to the surface is suppressed, the generation of active radicals is reduced, and the inorganic particle layer has a function of assisting the blocking layer effect. . Thereby, the energization deterioration in a high-temperature, high-humidity environment can be improved under even larger current energization conditions.

The effect on the type of inorganic particles will be described. The inorganic particles are preferably the same kind of inorganic particles as the toner external additive. In the electrophotographic process, the toner external additive plays an important role in establishing a cleaning system for residual toner. However, there is a possibility that a harmful effect of contaminating the surface of the charging roller by passing through a cleaning means such as a cleaning blade may occur. By using inorganic particles of the same type as the external additive against such charging roller contamination, not only the effect of suppressing current deterioration in a high-temperature and high-humidity environment under a large current energizing condition, but also an image resulting from charging roller contamination The effect of suppressing defects can also be expected. Therefore, it is more preferable to use silica (SiO ₂ ), titanium oxide (TiO ₂ ), and strontium titanate (SrTiO ₃ ), which are suitable materials as toner external additives, as inorganic particles, and one or more of them are used in combination.

(Electrophotographic equipment)
Next, an electrophotographic apparatus provided with the conductive roller of the present invention as a charging roller will be described. FIG. 6 is an example of an explanatory view schematically showing the electrophotographic apparatus of the present invention. The electrophotographic apparatus includes the following (1) to (7).
(1) Electrophotographic photoreceptor 17 (having axis 18 in FIG. 6),
(2) Charging means for charging the surface of the photoreceptor (charging roller 16 in FIG. 6),
(3) latent image forming means (exposure means 19 in FIG. 6) for exposing the photosensitive member to form a latent image;
(4) developing means 20 for supplying toner onto the photoreceptor;
(5) transfer means 21 for transferring the toner image on the photosensitive member to the transfer target;
(6) cleaning means 22 for cleaning the transfer residual toner on the photosensitive member;
(7) Fixing means 23 for fixing the transfer body on which the toner image is formed.

  As the electrophotographic photoreceptor, an electrophotographic photoreceptor having a photoconductive layer formed of an amorphous material mainly containing silicon atoms, or an organic photoreceptor having a total thickness of the surface protective layer and the photosensitive layer of 20 μm or less. It can be used suitably. As the charging means, it is desirable to use roller charging using the charging roller of the present invention by the proximity or contact method. This is because there is an effect of suppressing energization deterioration.

  As an electrophotographic photosensitive member having a photoconductive layer formed of an amorphous material mainly composed of silicon atoms, a photoconductive layer and a surface protective layer are sequentially laminated on a base made of a conductive material such as Al or stainless steel. It is a thing. In addition to these layers, various functional layers such as a blocking layer, an antireflection layer, or an interface layer may be provided as necessary. For example, by providing a blocking layer, an interface layer, etc., and selecting a dopant such as a group III element or a group V element, it is possible to control the charging polarity such as positive charging and negative charging. In the present invention, a positively chargeable silicon drum is desirable from the viewpoint of image defects such as image blur due to a chargeable product. The substrate shape may be as desired according to the driving method of the electrophotographic photosensitive member. As the base material, conductive materials such as Al and stainless are generally used. However, for example, various conductive materials such as various plastics and ceramics, particularly those having no conductivity, are deposited to be conductive. Those provided with can also be used. Examples of the photoconductive layer include amorphous materials in which silicon atoms include hydrogen atoms and halogen atoms (abbreviated as “a-Si (H, X)”). Further, the thickness of the photoconductive layer is not particularly limited, but about 15 to 50 μm is appropriate in consideration of the manufacturing cost. Furthermore, in order to improve the characteristics, a plurality of layers may be formed such as a lower photoconductive layer and an upper photoconductive layer. In particular, for a light source having a relatively long wavelength and almost no wavelength variation, such as a semiconductor laser, an epoch-making effect appears by devising such a layer structure. The surface protective layer is generally formed of a-SiC (H, X), but may be a-C (H, X). Further, it is preferable to control so that the interface reflection between the photoconductive layer and the surface protective layer is continuously changed to suppress the interface reflection of the portion.

As the organic photoreceptor having a total thickness of the surface protective layer and the photosensitive layer of 20 μm or less, for example, a conductive layer, an intermediate layer, a photosensitive layer, and a surface protective layer are arranged in this order on a base made of a conductive material such as Al or stainless steel. An electrophotographic photosensitive member is provided. The binder resin for the conductive layer is preferably a thermosetting phenol resin. As the intermediate layer, the volume resistivity of the intermediate layer is preferably set to 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm in order to prevent charge injection from the conductive layer to the photosensitive layer. Non-crystalline copolymerizable nylon and the like are preferable. The film thickness of the intermediate layer is preferably 0.1 to 2 μm. The photosensitive layer is separated into a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material even if it is a single layer type photosensitive layer containing the charge transporting material and the charge generating material in the same layer. The laminated photosensitive layer may be used. From the viewpoint of electrophotographic characteristics, the laminated photosensitive layer is preferred. The laminated photosensitive layer includes a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, and a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. However, a normal photosensitive layer is preferred from the viewpoint of electrophotographic characteristics. The film thickness of the photosensitive layer is desirably 15 μm or less. The surface protective layer is formed by applying a chain polymerizable compound having an unsaturated double bond onto the photosensitive layer and then curing it. The chain polymerizable compound can be cured by heat, but can also be cured using ultraviolet rays or electron beams. The thickness of the protective layer is desirably 1 to 5 μm. As the latent image forming means, a laser exposure apparatus using a semiconductor laser is preferably employed. As for the latent image forming method, for example, it is preferable to adopt a back scan method when an amorphous silicon photoconductor is used, and an image scan method when a thin film organic photoconductor is used. As the developing means, in the case of an amorphous silicon photoreceptor, it is preferable to use a two-component developing system using a developing carrier. The toner is a pulverized toner containing a styrene copolymer and an ester wax, and is negatively charged. Further, it is preferable to use titanium oxide, silica, or strontium titanate as the external additive. As the carrier, it is desirable to use magnetic dispersion type carrier particles. Regarding the developing system, in the case of an electrophotographic apparatus using an amorphous silicon photoconductor, a regular developing system using a positively charged photoconductor and a negatively chargeable toner is used. In the case of an electrophotographic apparatus using a thin film organic photoconductor, a developing carrier is used. It is preferable to adopt a two-component development system using The toner includes colored resin particles containing a binder resin, a colorant, and other additives as necessary, and colored particles to which an external additive such as colloidal silica fine powder is externally added. Yes. The toner is a negatively charged polyethylene resin, and the volume average particle diameter is preferably 5 μm or more and 8 μm or less. As the carrier, for example, surface-oxidized or non-oxidized iron, nickel, cobalt, manganese, chromium, rare earth and other metals, and their alloys, or oxide ferrite can be preferably used. The production method is not particularly limited. The carrier has a weight average particle diameter of 20 to 50 μm, preferably 30 to 40 μm, and a resistivity of 10 ⁷ Ωcm or more, preferably 10 ⁸ Ωcm or more. The developing system of the electrophotographic apparatus using the thin film organic photoreceptor in the present invention is a reversal developing system using a negatively charged photoreceptor and a negatively chargeable toner. As the transfer unit, it is preferable to use a transfer unit that directly transfers to a transfer target (paper, medium such as OHP) using a transfer roller, or a transfer unit that performs primary transfer to an intermediate transfer member such as a transfer belt. As the cleaning means, it is preferable to use a blade cleaning method using a blade-shaped member, a brush cleaning method using a brush-shaped member, or a method using both. The fixing unit is not particularly limited as long as the toner image transferred onto the transfer material 24 is fixed by heating, pressing, or heating and pressing.

The electrical resistance value when the conductive roller of the present invention is used as a charging roller will be described. FIG. 7 is an example of an explanatory diagram of a method for measuring by applying a DC voltage while rotating a conductive roller in a state of being pressed against a metal drum. It is desirable that the electric resistance value measured by applying 300 V is 1.0 × 10 ⁴ Ω or more and 1.0 × 10 ⁷ Ω or less. If it is less than 1.0 × 10 ⁴ Ω, it is easy to cause photoconductor leakage, and if it exceeds 1.0 × 10 ⁷ Ω, charging failure occurs and it becomes difficult to place a desired potential on the photoconductor. is there. A more preferable range of the electric resistance value is 5.0 × 10 ⁴ Ω or more and 1.0 × 10 ⁶ Ω or less.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these unless it exceeds the gist.

"Example 1"
The following materials were mixed with an open roll to prepare an unvulcanized rubber composition.
-Styrene-butadiene rubber (manufactured by JSR Corporation, JSR1502): 100 parts as unvulcanized rubber
・ Zinc oxide (Zinc oxide JIS2, manufactured by Shodo Chemical): 5 parts,
・ Calcium carbonate (Shiraishi calcium, Silver W): 20 parts,
・ Carbon black (mixed ketjen black and MT carbon): 45 parts,
・ Zinc stearate: 1 part
-As a plasticizer, adipic acid ester (manufactured by Dainippon Ink & Chemicals, Polysizer W305ELS): 10 parts,
・ Sulfur as a vulcanizing agent: 1 part
Dipentamethylene thiuram tetrasulfide (manufactured by Ouchi Shinsei Chemical Co., Noxeller TRA) as a crosslinking aid: 2 parts A die having an inner diameter of φ12 mm is set in the extruder schematically shown in FIG. Was adjusted to 80 ° C. Next, a support made of SUS shown in FIG. 8 was prepared and extruded with the above-mentioned unvulcanized rubber composition to form a cylindrical unvulcanized rubber composition layer around the core metal. . Thereafter, the unvulcanized rubber assembly layer at the end portion was cut and removed so as to have the shape shown in FIG. 9 to prepare an unvulcanized rubber roller.

Next, a step of forming a layer of inorganic particles on the unvulcanized rubber roller was performed using a powder coating apparatus schematically shown in FIG. An electrostatic coating apparatus was used as the powder coating apparatus. The following three types were used as inorganic particles.
・ Silica (Nippon Aerosil's hydrophobized product: (trade name) AEROSIL RX200, primary particle size 12 nm),
-Titanium oxide (manufactured by Teika, hydrophobized product: (trade name) MT-100T, primary particle size 15 nm),
Strontium titanate (manufactured by Titanium Industry Co., Ltd .: (trade name) SW-360 / zinc stearate 3% treated product, primary particle size 50 nm).

  Thus, an unvulcanized rubber roller in which each of the above inorganic particle layers was formed was obtained.

  Next, each of the powder-coated unvulcanized rubber rollers was pressed and vulcanized with inorganic particles using a pressure vulcanizing apparatus schematically shown in FIG. The surface of the pressure contact member was coated with a silicone release agent. An IH heater was installed inside the pressure contact member. The surface was heated at 80 ° C. for 15 minutes while the powder-coated unvulcanized rubber roller was in contact with the pressure contact member. Thereafter, the temperature of the pressure contact member was changed to 160 ° C. and heated for 30 minutes. The pressure welding load was applied with a weight of 1 kg on one side. Thereafter, the roller was removed from the pressure contact member, and the temperature inside the pressure vulcanization apparatus was kept at 160 ° C. for 1 hour with hot air to complete the vulcanization. Through these steps, a conductive roller was produced in which three types of inorganic particles of silica, titanium oxide, and strontium titanate were embedded in the surface. A cross section was cut out from one of the surfaces, and the cross section was observed with a transmission electron microscope (H-9500, manufactured by Hitachi, Ltd.) to determine the layer thickness of the inorganic particles based on the roller surface. In the case of silica, the layer thickness was 120 nm. In the case of titanium oxide, the layer thickness was 150 nm. In the case of strontium titanate, the layer thickness was 500 nm.

(Electrical degradation test)
The Canon copier GP405 was modified and the process speed was set to 400 mm / s. The charging bias was supplied from an external power source. The charging conditions, exposure method, and developing means were set to the methods / conditions described below according to the photosensitive drum. The modified machine is shown in FIG. The photoreceptor was tested using two types of photoreceptors. The amorphous silicon (a-Si) photoconductor is a positively charged a-Si photoconductor that is sequentially laminated on the surface of a conductive support made of φ80 mm Al, and includes a negative charge blocking layer and a photoconductive layer. A photosensitive drum composed of a surface protective layer was used. Regarding the toner and carrier, the toner is a negatively charged pulverized toner in which an ester wax and a colorant are dispersed in a styrene copolymer, and silica, titanium oxide, and strontium titanate are used as external additives. The average particle size of the toner was 6.8 μm. As the carrier, magnetic particle-dispersed carrier particles in which magnetite was dispersed in a phenol resin were used. The average particle size of the carrier is 35 [mu] m, and the resistivity was 10 ⁹ [Omega] cm. As the developing means, a two-component developing system using a developing carrier was used. The charging conditions are DC voltage +600 V, AC voltage 1.5 kV, and AC frequency 3.5 kHz. The exposure method was changed to the back scan method.

The thin film organic photoreceptor has an aluminum cylinder, a photosensitive layer, and a protective layer. The photosensitive layer may be an intermediate layer having a thickness of 1 μm containing an electron transporting organic compound, a charge generating layer having a thickness of 0.15 μm containing a phthalocyanine charge generating substance, and a triarylamine charge transport material. And a charge transport layer having a layer thickness of 10 μm. The protective layer is a protective layer having a layer thickness of 5 μm made of a photopolymerizable compound having a layer thickness of 5 μm. The toner used was a pulverized toner in which carbon black was dispersed as a colorant in a negatively charged polyethylene resin externally added with silica and titanium oxide. The average particle size of the toner was 7.0 μm. The carrier used oxide ferrite. The average particle diameter of the carrier was 30 μm, and the resistivity was 10 ⁸ Ωcm. As the developing means, a two-component developing system using a developing carrier was used. Charging conditions were set to a DC voltage of −750 V, an AC voltage of 2.0 kV, and an AC frequency of 3.2 kHz, and an exposure method was an image scanning method. A conductive roller embedded with silica, titanium oxide, and strontium titanate prepared in Example 1 is mounted with a charging roller and a photoconductor, and is passed through in a high temperature and high humidity environment (H / H: 30 ° C./80% RH). A paper durability test was conducted. The electric resistance value was measured using the apparatus shown in FIG. The electrical resistance value before endurance was selected from 5.0 × 10 ⁴ Ω to 2.0 × 10 ⁵ Ω conductive roller, and the electrical resistance value of the charging roller after 250,000 sheets was measured. . The evaluation of energization deterioration was performed according to the following criteria.
A: The electric resistance value of the charging roller after endurance of 250,000 sheets is 5.0 × 10 ⁴ Ω or more and less than 5.0 × 10 ⁶ Ω. It showed very good energization durability.
○: The electric resistance value of the charging roller after endurance of 250,000 sheets is 5.0 × 10 ⁶ Ω or more and less than 1.0 × 10 ⁷ Ω. Although the current-carrying durability was slightly inferior, it was at a level causing no practical problems.
X: The electric resistance value of the charging roller after durability of 250,000 sheets is 1.0 × 10 ⁷ Ω or more. The current-carrying durability was not good, and it was not at a level that could withstand practical use.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration /
Inorganic particles / titanium oxide: Evaluation of current deterioration / ◎
Inorganic particles / Strontium titanate: Evaluation of current deterioration / ◎
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration /
Inorganic particles / titanium oxide: Evaluation of current deterioration / ◎
Inorganic particles / Strontium titanate: Evaluation of current deterioration / ◎
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has a sufficient effect on the deterioration of energization.

"Example 2"
The following ingredients were mixed on an open roll.
-As an unvulcanized rubber, 100 parts of styrene-butadiene rubber (manufactured by JSR, JSR1502),
・ Zinc oxide (Zinc oxide JIS2, manufactured by Shodo Chemical) 5 parts,
・ 20 parts of calcium carbonate (Shiraishi calcium, Silver W),
・ 45 parts of carbon black (mixture of ketjen black and MT carbon)
-1 part zinc stearate,
・ 10 parts of adipic acid ester (manufactured by Dainippon Ink & Chemicals, Polysizer W305ELS) as a plasticizer,
・ 1 part of sulfur as vulcanizing agent,
-2 parts of dipentamethylene thiuram tetrasulfide (manufactured by Ouchi Shinsei Chemical Industry, Noxeller TRA) as a crosslinking aid.

  In order to mold the obtained unvulcanized rubber layer around the support, a die having an inner diameter of φ12 mm was set in the extruder schematically shown in FIG. 1, and the temperature of the crosshead was adjusted to 80 degrees in advance. . Next, a support made of SUS shown in FIG. 8 was prepared and extruded together with rubber to form a cylindrical unvulcanized rubber composition layer around the core metal. Thereafter, the unvulcanized rubber assembly layer at the end portion was cut and removed so as to have the shape shown in FIG. 9 to prepare an unvulcanized rubber roller.

  Next, a process of vulcanizing while embedding inorganic particles in an unvulcanized rubber roller was performed using an apparatus that can simultaneously perform powder coating and pressure vulcanization shown in FIG. A spray coating apparatus was used as the powder coating apparatus. The same three types of inorganic particles as in Example 1 were used.

  Three unvulcanized rubber rollers each having a layer of inorganic particles were produced. The surface of the pressure contact member was coated with a silicone release agent. An IH heater was installed inside the pressure contact member. The surface was heated at 80 ° C. for 15 minutes while the powder-coated unvulcanized rubber roller was in contact with the pressure contact member. Thereafter, the temperature of the pressure contact member was changed to 160 ° C. and heated for 30 minutes. The pressure welding load was applied with a weight of 1 kg on one side. Thereafter, the roller was removed from the pressure contact member, and the temperature inside the pressure vulcanization apparatus was kept at 160 ° C. for 1 hour with hot air to complete the vulcanization. Through these steps, three conductive rollers each having three kinds of inorganic particles of silica, titanium oxide, and strontium titanate embedded in the surface were produced. A cross section was cut out from one of the surfaces, and the cross section was observed with a TEM to determine the layer thickness of the inorganic particles based on the roller surface. In the case of silica, the layer thickness was 180 nm. In the case of titanium oxide, the layer thickness was 225 nm. In the case of strontium titanate, the layer thickness was 750 nm.

(Electrical degradation test)
A test similar to that of Example 1 was performed except that the conductive roller manufactured by the manufacturing method of Example 2 was mounted as a charging roller.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration /
Inorganic particles / titanium oxide: Evaluation of current deterioration / ◎
Inorganic particles / Strontium titanate: Evaluation of current deterioration / ◎
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration /
Inorganic particles / titanium oxide: Evaluation of current deterioration / ◎
Inorganic particles / Strontium titanate: Evaluation of current deterioration / ◎
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has a sufficient effect on the deterioration of energization.

"Example 3"
The conductive roller embedded with inorganic particles was manufactured in the same manner as in Example 1 except that the setting of the heating temperature of the pressure contact member at 80 ° C. for 15 minutes and then 160 ° C. for 30 minutes was changed to 160 ° C. for 45 minutes. The same electrification deterioration test as in Example 1 was performed using the prepared charging roller. Cross-sectional observation was performed with a TEM to determine the layer thickness of the inorganic particles based on the roller surface. In the case of silica, the layer thickness was 60 nm. In the case of titanium oxide, the layer thickness was 75 nm. In the case of strontium titanate, the layer thickness was 250 nm.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has an effect that there is no practical problem with respect to the deterioration of energization.

Example 4
The conductive roller embedded with inorganic particles was manufactured in the same manner as in Example 2 except that the setting of the heating temperature of the pressure contact member at 80 ° C. for 15 minutes and then 160 ° C. for 30 minutes was changed to 160 ° C. for 45 minutes. The same electrification deterioration test as in Example 2 was performed using the prepared charging roller. Cross-sectional observation was performed with a TEM to determine the layer thickness of the inorganic particles based on the roller surface. In the case of silica, the layer thickness was 85 nm. In the case of titanium oxide, the layer thickness was 100 nm. In the case of strontium titanate, the layer thickness was 350 nm.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has an effect that there is no practical problem with respect to the deterioration of energization.

"Example 5"
Except that the inorganic particles to be applied were the following three types, a conductive roller embedded with inorganic particles was produced by the same manufacturing method as in Example 1 and used as a charging roller. A deterioration test was conducted.
・ Silica (Nippon Aerosil Co., Ltd .: (trade name) AEROSIL 200, primary particle size 12 nm)
・ Titanium oxide (manufactured by Teica: (trade name) MT-150W, primary particle size 15 nm)
Except for changing to strontium titanate (manufactured by Titanium Industry Co., Ltd .: (trade name) SW-360 / untreated, primary particle size 50 nm), cross-sectional observation is performed with TEM, and the layer thickness of the inorganic particles based on the roller surface Asked. In the case of silica, the layer thickness was 70 nm. In the case of titanium oxide, the layer thickness was 85 nm. In the case of strontium titanate, the layer thickness was 300 nm.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has an effect that there is no practical problem with respect to the deterioration of energization.

"Example 6"
A conductive roller was produced in the same manner as in Example 2 except that the supplied inorganic particles were changed to the following three types.
・ Silica (Nippon Aerosil Co., Ltd .: (trade name) AEROSIL 200, primary particle size 12 nm)
・ Titanium oxide (manufactured by Teica: (trade name) MT-150W, primary particle size 15 nm)
Strontium titanate (manufactured by Titanium Industry Co., Ltd .: (trade name) SW-360 / untreated, primary particle size 50 nm)
Using the obtained conductive roller as a charging roller, an energization deterioration test similar to that in Example 2 was performed. Moreover, cross-sectional observation was performed by TEM, and the layer thickness of the inorganic particles based on the roller surface was obtained. In the case of silica, the layer thickness was 90 nm. In the case of titanium oxide, the layer thickness was 110 nm. In the case of strontium titanate, the layer thickness was 400 nm.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / silica: Evaluation of current deterioration / ○
Inorganic particles / titanium oxide: Evaluation of current deterioration / ○
Inorganic particles / strontium titanate: Evaluation of current deterioration / ○
As described above, the conductive roller in which the irrational particles are embedded by the manufacturing method of the present invention has an effect that there is no practical problem with respect to the deterioration of energization.

“Comparative Example 1”
A conductive roller without an inorganic particle layer was produced without performing step (ii) by the same production method as in Example 1, and an energization deterioration test similar to that in Example 1 was performed using it as a charging roller.
The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / None: Evaluation of current deterioration / ×
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / None: Evaluation of current deterioration / ×
As described above, the conductive roller in which the irrational particles are not embedded does not have a sufficient effect on the deterioration of energization.

“Comparative Example 2”
A conductive roller without an inorganic particle layer was produced without supplying inorganic particles by the same production method as in Example 2, and the same energization deterioration test was performed using the roller as a charging roller.

  The results of the energization deterioration test were as follows.

When the photoconductor is amorphous silicon Inorganic particles / None: Evaluation of current deterioration / ×
When the photoreceptor is a thin-film organic photoreceptor Inorganic particles / None: Evaluation of current deterioration / ×
As described above, the conductive roller in which the irrational particles are not embedded does not have a sufficient effect on the deterioration of energization.

It is a schematic diagram of the process of forming the layer of electroconductive unvulcanized rubber on a support body. It is a schematic diagram of the process of forming the layer of an inorganic particle on the surface of the layer of an unvulcanized rubber. It is a schematic diagram of the process of forming the rubber layer with which the inorganic particle was embedded. (A) is a front view, (b) is a side view. It is a schematic diagram of the process of forming the rubber layer with which the inorganic particle was embedded, supplying an inorganic particle to a type | mold. (A) is a front view, (b) is a side view. It is a schematic diagram of the layer of the embedded inorganic particle. 1 is a schematic diagram of an electrophotographic apparatus of the present invention. It is a schematic diagram of the electrical resistance measuring apparatus used by this invention. It is a schematic diagram of the support body used by this invention. It is a schematic diagram of the electroconductive roller used by this invention.

Explanation of symbols

1. Extruder 2. Crosshead 3. 3. Feed roller 4. Unvulcanized rubber roller Holding jig 6. 6. Powder coating apparatus 7. Unvulcanized rubber roller with a layer of inorganic particles Pressure contact member 9. Holding member 10. Motor 11. Rail 12. Weight 13 Roller holding member 14. Pressurizing device 15. Pressure member rotating jig 16. Charging roller 17. Electrophotographic photoreceptor 18. Axis 19. Exposure means 20. Developing means 21. Transfer means 22. Cleaning means 23. Fixing means 24. Transfer material

Claims (7)

(I) forming a conductive unvulcanized rubber layer on the support;
(Ii) forming an inorganic particle layer on the surface of the unvulcanized rubber layer;
(Iii) While pressing the mold against the surface of the inorganic particle layer, the unvulcanized rubber is added while changing the pressing position of the mold against the entire inorganic particle layer at regular intervals. Vulcanizing and forming a rubber layer embedded with the inorganic particles;
The manufacturing method of the electroconductive roller which has. (I) forming a conductive unvulcanized rubber layer on the support;
(Ii) While pressing the mold against the surface of the unvulcanized rubber layer, the pressing position of the mold is changed so as to press the entire unvulcanized rubber layer at regular intervals, Supplying inorganic particles to the surface of the mold in a region not pressed against the vulcanized rubber layer and vulcanizing the unvulcanized rubber to form a rubber layer embedded with the inorganic particles;
The manufacturing method of the electroconductive roller which has.   3. The unvulcanized rubber is vulcanized after the embedding of the inorganic particles is controlled by controlling a mold that is pressed against the surface of the unvulcanized rubber layer. Production method.   4. The production method according to claim 1, wherein the mold is subjected to a releasable surface treatment.   The manufacturing method according to claim 1, wherein the inorganic particles are subjected to a hydrophobic treatment.   6. The production method according to claim 1, wherein the inorganic particles are silica, titanium oxide, or strontium titanate.   An electrophotographic apparatus using the conductive roller manufactured by the manufacturing method according to claim 1 as a charging roller.