JP5509877B2 - Annular member, charging device, image forming apparatus, and manufacturing method of annular member - Google Patents

Description

  The present invention relates to an annular member, a charging device, an image forming apparatus, and a method for manufacturing the annular member.

In Patent Document 1, a shaft is coaxially penetrated into a cylindrical member, and a space between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the shaft or a cylindrical shape at both ends of the cylindrical member. A shaft body having a configuration in which a cylindrical fixture is fitted on the outer periphery of a member has been proposed.
Patent Document 2 proposes a roll for an electrophotographic copying machine in which a rubber layer is provided on a core bar whose outer diameter at the center in the width direction is larger than both ends in the width direction.

  In Patent Document 3, as a method for manufacturing a rubber roller having an outer shape of a drum shape (so-called crown shape), the moving speed of the core metal is set to the width of the core metal in a state where the supply amount of the unvulcanized rubber material is stabilized. It has been proposed to change the outer diameter of the rubber layer formed on the cored bar by changing it according to the position in the direction.

  In Patent Document 4, a rubber roll having an outer diameter of a drum shape is manufactured by extrusion molding. In a manufacturing apparatus for performing the extrusion molding, a core bar guide is provided in a region where a core metal is covered with a rubber material. It has been proposed that the outer diameter of the rubber layer to be extruded is changed by increasing or decreasing the pressure when the rubber material is brought into close contact with the core metal or the section where the rubber material is brought into close contact with the gold guide.

JP 2004-278590 A Japanese Patent Laid-Open No. 9-255854 Japanese Patent Laid-Open No. 2003-300279 JP 2006-305770 A

  The present invention is compared with the case where the residual strain in the center portion in the width direction of the elastic layer in which the outer diameter at the center portion in the width direction is larger than the outer diameter at both ends in the width direction is not smaller than both end portions in the width direction Even after the pressure is applied from the outer peripheral side, the annular member, the charging device, the image forming apparatus, and the annular member that are excellent in retaining the shape of the elastic layer when released from the pressure. It is an object to provide a manufacturing method.

The invention according to claim 1 is provided on the core body and the core body, the outer diameter of the central portion in the width direction is larger than the outer diameter of both end portions in the width direction, and the residual strain in the central portion in the width direction is wide. An elastic layer smaller than both ends in the direction, and an annular member having a lower coefficient of dynamic friction at the center in the width direction of the core than at both ends in the width direction .

The invention according to claim 2 is the annular member according to claim 1, wherein the minimum value of the dynamic friction coefficient in the central portion in the width direction of the core is 0.1 or more and 0.8 or less.

The invention according to claim 3 is a charging device including the annular member according to claim 1 or claim 2 .

According to a fourth aspect of the present invention, there is provided an image carrier, a charging device that charges the image carrier, a latent image forming device that forms an electrostatic latent image on the image carrier charged by the charging device, and A developing device that develops the electrostatic latent image on the image holding member with toner, and a transfer device that transfers the toner image formed on the image holding member to the transfer target by the developing device. At least one of the apparatus, the developing device, and the transfer device is an image forming apparatus including the annular member according to claim 1 or 2 .

The invention according to claim 5 is the manufacturing of the annular member according to claim 1, further comprising a step of providing an elastic layer by extrusion molding on a core body having a dynamic friction coefficient at a center portion in the width direction lower than both end portions in the width direction. Is the method.

The invention according to claim 6 is the method for manufacturing the annular member according to claim 5 , wherein the minimum value of the dynamic friction coefficient in the central portion in the width direction of the core is 0.1 or more and 0.8 or less.

  According to the first aspect of the present invention, the residual strain at the center portion in the width direction of the elastic layer in which the outer diameter of the center portion in the width direction is larger than the outer diameters at both end portions in the width direction is the both end portions in the width direction. Compared to the case where the pressure is not smaller, an annular member is provided that is excellent in retention of the shape of the elastic layer when released from the pressure even after the pressure is applied from the outer peripheral side. There is an effect.

In addition, according to the invention according to claim 1 , the shape of the elastic layer is more favorably maintained as compared with the case where the coefficient of friction at the center in the width direction of the core is equal to or greater than both ends in the width direction. There is an effect.

According to the invention according to claim 2 , the effect that the shape of the elastic layer is more satisfactorily maintained as compared with the case where the minimum value of the friction coefficient in the central portion in the width direction of the core is outside the scope of the present application. Play.

According to the third aspect of the present invention, in comparison with the charging device that does not include the annular member of the present invention, there is a problem when the annular member that does not include the elastic layer whose residual strain in the width direction is smaller than both end portions in the width direction. The effect is to be suppressed.

According to the fourth aspect of the present invention, in comparison with the image forming apparatus that does not include the annular member of the present invention, when the annular member that does not include the elastic layer whose residual strain in the width direction is smaller than both end portions in the width direction is provided. There is an effect that the defect is suppressed.

According to the invention which concerns on Claim 5 , compared with the case where it is outside the range of this application of the friction coefficient in the center part of the width direction of a core, the annular member by which the shape of the elastic layer was hold | maintained more favorably is produced. , Has the effect.

According to the invention of claim 6, when the ratio of the maximum value of the friction coefficient at both end portions in the width direction of the core body to the minimum value of the friction coefficient in the center portion in the width direction of the core body is outside the scope of the present application. As compared with the above, there is an effect that an annular member in which the shape of the elastic layer is more favorably maintained is produced.

It is a schematic diagram which shows the annular member of this Embodiment, (A) is sectional drawing cut | disconnected in the width direction, (B) is sectional drawing cut | disconnected in the direction which cross | intersects the width direction. It is a schematic diagram which shows the core in the annular member of this Embodiment. It is a schematic diagram which shows an example of the extrusion molding apparatus used in manufacture of the annular member of this Embodiment. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic diagram which shows an example of the process cartridge of this Embodiment.

(Annular member)
As shown in FIGS. 1A and 1B, the annular member 10 of the present embodiment includes a core body 12 and an elastic layer 14 provided on the outer surface of the core body 12. Yes.
As shown in FIG. 1 (B), the elastic layer 14 has a shape in which the outer diameter at the center in the width direction is larger than the outer diameter at both ends in the width direction. And the residual distortion of the center part of the width direction of this elastic layer 14 is smaller than the both ends of the width direction.
The shape (outer shape) of the elastic layer 14 may be any shape as long as the outer diameter of the central portion in the width direction is larger than the outer diameters of the both end portions in the width direction. 1 may have a shape with a large outer diameter, or may have a shape with a continuously large outer diameter from both end portions in the width direction toward the center portion, as shown in FIG. The shape is not limited to a shape having a continuously large outer diameter (so-called crown shape) from the center toward the center.

  Here, the annular member 10 may be used by pressing both end portions in the width direction of the core body 12 toward the contact target member to bring the outer peripheral surface of the elastic layer 14 into contact with the contact target member. . Due to the bending of the core body 12 at this time, the contact per unit length (unit length in the direction crossing the width direction) of the elastic layer 14 with the member to be contacted at the both ends and the center in the width direction. The area may be different. For this reason, conventionally, in order to make this contact area uniform, the shape of the elastic layer 14 has been made such that the outer diameter of the central portion in the width direction is larger than the outer diameter of both end portions in the width direction. Yes. However, in the apparatus in which the annular member 10 is mounted, if the annular member 10 is held in a state where it is in contact with the member to be contacted without being rotated, the elastic layer 14 is deformed and released from the pressure. After being done, this shape (a shape in which the outer diameter of the central portion in the width direction is larger than the outer diameters of both end portions in the width direction) may not be maintained.

  On the other hand, the elastic layer 14 of the annular member 10 of the present embodiment has an outer diameter at the central portion in the width direction larger than the outer diameter at both end portions in the width direction, and residual strain at the central portion in the width direction is Smaller than both ends. As a result, although the reason is not clear, the residual strain at the central portion in the width direction of the elastic layer 14 having a shape in which the outer diameter of the central portion in the width direction is larger than the outer diameters at both end portions in the width direction is smaller than both end portions in the width direction. Even when the pressure was applied from the outer peripheral side as compared with the case where there was no pressure, the effect of excellent retention of the shape of the elastic layer 14 was exhibited when the pressure was released from the pressure.

  In the present embodiment, “both end portions in the width direction of the elastic layer 14” refers to a region including a region continuous with both end surfaces in the width direction of the elastic layer 14 and not including the central portion of the elastic layer 14. . The “central portion in the width direction of the elastic layer 14” means the center in the width direction of the elastic layer 14 (a position that is half the length in the width direction of the elastic layer 14 from both end surfaces) and the both end portions of the elastic layer 14 Indicates an area not included.

  Further, “both ends in the width direction of the core body 12” means both end surfaces in the width direction of the elastic layer 14 (or the formed elastic layer 14) formed on the core body 12 in the width direction of the core body 12. The area | region which includes a continuous position and does not include the center part of the core 12 is shown. “The central portion of the core body 12 in the width direction” means the center of the core body 12 in the width direction (a position half the length in the width direction of the core body 12 from both end faces) and the both ends of the core body 12. Indicates an area not included.

Note that the boundary between the central portion and both end portions where the outer diameter of the annular member 10 changes in the width direction of the elastic layer 14, and the central portion and both end portions where the residual strain changes in the width direction of the elastic layer 14. The position may be completely coincided with or shifted from the boundary.
Further, in the produced annular member 10, the boundary where the dynamic friction coefficient of the core body 12 changes and the boundary where the elastic layer 14 changes in the outer diameter or residual strain may completely match, It may be shifted.

  The residual strain of the elastic layer 14 is determined by measuring the surface straightness of the initial shape of the produced rubber roll in the axial direction in advance with a laser outer diameter measuring instrument (manufactured by Asaka Riken) and measuring the elastic layer at the location where the residual strain is measured. After cutting, the same part of the elastic layer remaining on the core body side is again measured for straightness in the axial direction, and the degree to which the elastic layer on the cut end surface is bounced (outer diameter growth by releasing the constraint) is obtained.

  Hereinafter, each layer configuration will be described in detail.

(Core)
The core body 12 is a columnar member that functions as an electrode and a support member of the annular member 10. Examples of the constituent material of the core body 12 include metals such as iron (free-cutting steel, etc.), stainless steel, aluminum, copper, brass, nickel, and the like. Examples of the core 12 include a member (for example, a resin or a ceramic member) whose outer surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The core body 12 may be a hollow member (cylindrical member) or a non-hollow member.

  The dynamic friction coefficient of the central portion in the width direction of the core body 12 (see the region 12A in FIG. 2) is preferably smaller than both end portions in the width direction (see the region 12B in FIG. 2). The dynamic friction coefficient of the central portion in the width direction of the core body 12 is configured to be smaller than both end portions in the width direction. It is considered that the elastic layer 14 having a shape in which the outer diameter of the central portion in the width direction is larger than the outer diameters of both end portions in the width direction (details will be described in the description column of the manufacturing process described later).

  The minimum value of the dynamic friction coefficient at the center in the width direction of the core body 12 is preferably 0.1 or more and 0.8 or less. However, it is necessary to maintain a coefficient of friction that prevents the core and rubber from completely separating and falling off during extrusion molding. Since the minimum value of the dynamic friction coefficient in the central portion in the width direction of the core body 12 is within the above range, the elastic layer 14 can be easily contracted in the axial direction in the manufacturing process of the annular member 10 to be described later. Make the outer diameter larger than the end.

In the present embodiment, the dynamic friction coefficient of the core body 12 indicates the dynamic friction coefficient between the outer peripheral surface of the core body 12 and the elastic layer 14.
The dynamic friction coefficient between the core body 12 and the elastic layer 14 is measured using a surface dynamic friction coefficient measuring machine HEIDON (14) manufactured by Shinto Kagaku Co., Ltd.

  Specifically, the dynamic friction coefficient between the core 12 and the elastic layer 14 is obtained by molding a rubber sheet by vulcanizing a rubber compound having the same composition as the elastic layer 14 using a vulcanizing press and a mold at 180 ° C. for 30 minutes. Then, a test piece (50 mm × 50 mm, thickness 2.0 mm) is prepared from the sheet, and the surface of the core body 12 and the test piece are brought into surface contact with each other by using the dynamic friction coefficient measuring machine, and the test piece is fixed. The core body 12 was moved, and measurement was performed under the conditions of a temperature of 22 ° C., a humidity of 55% RH, a moving speed of 5 mm / sec, and a load of 500 g.

  The dynamic friction coefficient of the outer peripheral surface of the core body 12 may be adjusted by a known method, and mechanical processing is applied to the outer peripheral surface of the core body 12, a coating liquid is applied to the outer peripheral surface of the core body 12, The method of surface-treating, such as plating, is mentioned. For example, as a method for adjusting the dynamic friction coefficient of the outer peripheral surface of the core body 12, specifically, for example, a method of partially processing the surface of the core body 12 such as a shot blasting process, A method of partially applying a coating liquid containing a powder such as carbon may be used.

(Elastic layer)
The elastic layer 14 is made of a rubber material whose main component is a rubber raw material. The “main component” indicates that the content of the rubber raw material in the rubber material is 80% by mass or more.

  Examples of the rubber material include nitrile butadiene rubber, epichlorohydrin rubber, styrene butadiene rubber, butadiene rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene terpolymer rubber (EPDM), silicone rubber, urethane rubber, Isoprene rubber, chloroprene rubber, butyl rubber, fluorine rubber, nitrile rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, etc., and mixtures thereof Rubber. These rubber raw materials may be foamed or non-foamed.

  When the annular member 10 is used as a member for forming an electric field such as a charging device or a transfer device described later in an electrophotographic image forming apparatus, a conductive agent is added to the rubber material constituting the elastic layer 14. Is done.

  Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide And various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals ; These conductive agents may be used alone or in combination of two or more.

  The addition amount of the conductive agent is not particularly limited, but in the case of the electronic conductive agent, a range of 1 part by weight to 80 parts by weight or 15 parts by weight with respect to 100 parts by weight of the rubber material constituting the elastic layer 14. A range of not less than 80 parts and not more than 80 parts by mass is exemplified. On the other hand, in the case of the ionic conductive agent, with respect to 100 parts by mass of the rubber material constituting the elastic layer 14, 0.1 parts by mass or more and 5.0 parts by mass or less, or 0.5 parts by mass or more and 3.0 parts by mass or less. The following ranges are mentioned.

  Furthermore, you may mix | blend another additive with the rubber material which comprises this elastic layer 14. FIG. Other additives include inorganic fillers, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, and other materials that are usually added to rubber layers. Is mentioned.

  Examples of the vulcanizing agent include vulcanizing agents that vulcanize by extracting a halogen group such as sulfur or 2,4,6-trimercapto-s-triazine, 6-methylquinoxaline-2,3-dithiocarbamate. These may be used alone or in combination of two or more.

  Examples of the vulcanization accelerator include thiazole, sulfenamide, thiuram, dicarbamate and xanthate. These may be used alone or in combination of two or more. In addition, known rubber compounding materials such as zinc oxide and stearic acid can be added. These may be used alone or in combination of two or more.

The hardness of the elastic layer 14 varies depending on the apparatus to which the annular member 10 is applied. However, when the annular member 10 is used for a charging device of an electrophotographic image forming apparatus to be described later, the Asker C hardness is 15 °. The range is 90 ° or less and 15 ° or more and 70 ° or less.
The Asker C hardness was measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of a measurement sheet having a thickness of 3 mm.

The volume resistivity of the elastic layer 14 varies depending on the device to which the annular member 10 is applied. However, when the annular member 10 is used for a charging device of an electrophotographic image forming apparatus described later, for example, 10 ³ Ωcm. For example, 10 ¹⁴ Ωcm or less.

  The volume resistivity is measured with respect to a sheet-like measurement sample by using a measuring jig (R12702A / B resiliency chamber: manufactured by Advantest) and a high resistance measuring device (R8340A digital high resistance / microammeter: Advantest). The voltage adjusted so that the electric field (applied voltage / composition sheet thickness) is 1000 V / cm is calculated from the current value after application for 30 seconds using the following formula (1).

  Volume resistivity (Ω · cm) = (19.63 × applied voltage (V)) / (current value (A) × measurement sample sheet thickness (cm)) (1)

(Method for producing annular member)
Next, the manufacturing method of the annular member 10 of this Embodiment is demonstrated.

  The annular member 10 of the present embodiment is manufactured by forming the elastic layer 14 by extrusion molding on the outer peripheral surface of the core body 12 having the adjusted dynamic friction coefficient as described above. As described above, the core body 12 used for manufacturing the annular member 10 has a configuration in which the dynamic friction coefficient at the center portion in the width direction of the core body 12 is smaller than both end portions in the width direction.

  FIG. 3 shows an example of the extrusion molding apparatus (extrusion molding apparatus 50) used for producing the annular member 10 of the present embodiment.

  The extrusion molding apparatus 50 shown in FIG. 3 is an uniaxial rubber extruder that includes an extruder 66 and a crosshead die 68. A crosshead die 68 is connected to the extruder 66, and the unvulcanized rubber material 15A is caused to flow in a direction intersecting the extrusion direction of the extruder 66. Here, the unvulcanized rubber material 15A filled in the charging portion (hopper) 67A is plasticized by the screw 69 in the cylinder 67 provided in the horizontal direction, and is extruded from the extruder 66 and then plasticized. The cross head die 68 is arranged so that the unvulcanized rubber material 15A falls in the vertical direction.

  As this screw diameter, 30 mm or more and 90 mm or less are mentioned.

  The interior of the crosshead die 68 has a substantially conical shape with the lower side at the top, and an inflow hole 74 connected to the outlet 72 of the extruder 66 is formed on the peripheral surface. A cylindrical cored bar holder 76 that holds the outer peripheral surface of the core body 12 is provided at the center of the crosshead die 68.

  A guide tube 78 is provided outside the cored bar holder 76. The guide cylinder 78 guides the unvulcanized rubber material 15 </ b> A flowing from the inflow hole 74.

  A die 80 is provided on the exit side of the crosshead die 68. By this die 80, the core body 12 and the unvulcanized rubber material 15A are subjected to pressure bonding and outer diameter control, and the unvulcanized rubber layer 15 is obtained.

  In the extrusion molding apparatus 50 configured as described above, the unvulcanized rubber material 15A is extruded using the extruder 66 provided in the cylinder 67, and the core body 12 is supplied to the crosshead die 68. 68 is passed. As a result, an unvulcanized rubber layer 15 made of the unvulcanized rubber material 15 </ b> A is formed on the outer peripheral surface of the core body 12.

  In the manufacture of the core body 12 of the present embodiment, the core body 12 used for extrusion molding is configured such that the dynamic friction coefficient at the center portion in the width direction of the core body 12 is smaller than both end portions in the width direction as described above. ing. For this reason, by the extrusion molding apparatus 50. The rubber material is extruded onto the surface of the core body 12, and the core body 12 whose dynamic friction coefficient is adjusted as described above passes through the crosshead die 68 continuously or intermittently, thereby being extruded onto the surface of the core body 12. When the degree of shrinkage due to storage elasticity of the rubber material changes in the width direction of the core body 12 and is released from the extrusion molding apparatus 50, the diameter in the cross-sectional direction that is inversely proportional to the degree of shrinkage in the width direction, that is, annular The outer diameter of the member 10 is a shape in which the outer diameter of the central portion in the width direction is larger than the outer diameters of both end portions in the width direction.

  Then, the core body 12 on which the unvulcanized rubber layer 15 is formed on the outer peripheral surface is discharged through the die 80 and cut. Then, the unvulcanized rubber layer 15 formed on the core body 12 discharged through the die 80 is heated by an oven, a heating device (not shown) such as microwave vulcanization or hot air vulcanization. Is vulcanized. Accordingly, the elastic layer 14 has an outer diameter at the center portion in the width direction larger than the outer diameters at the both end portions in the width direction and the residual strain at the center portion in the width direction is smaller than both end portions in the width direction. The provided annular member 10 is produced.

In addition, in the extrusion molding apparatus 50 of this Embodiment, about the supply of the core 12, there is no need of complicated speed control etc., it may be supplied at equal speed and according to gravity or the discharge pressure of a rubber material. May be supplied at different rates.

Here, since the rubber material is a substance having viscoelastic properties, even if it receives deformation stress, a part of the stress is replaced with thermal energy as loss elasticity, and the deformation is accepted, and the remaining stress is stored elasticity ( It is stored internally as energy for reversible shape restoration. By the action of the storage elasticity, the rubber material formed on the surface of the core body 12 by the extrusion molding device 50 is released from the restraining force by the die 80 and the core body 12 (that is, released from the extrusion molding device 50). After that, the shape before being formed by the die 80 and the core body 12 is restored to some extent. This phenomenon is generally referred to as shrink.
Due to a phenomenon called shrink, the elastic layer 14 formed on the core body 12 by the extrusion molding apparatus 50 contracts in the width direction of the core body 12 (width direction of the elastic layer 14), expands in the thickness direction, and It is considered that the portion contracted in the width direction can be directly replaced by expansion in the thickness direction. Further, the degree of shrinkage is considered to be larger as the restrained time is shorter. This is a phenomenon caused by the stress relaxation property of the rubber material, and depends on the difference of the rubber material in addition to the time, but the shrinkage of the rubber material by the die 80 and the core body 12 is shorter and the shrinkage is larger. Is considered to be a universal property regardless of the formulation.

  The inventors use the shrink mechanism in the annular member 10 of the present embodiment to make the core body 12 in the region (the central portion in the width direction of the elastic layer 14) where the outer diameter of the elastic layer 14 is desired to be increased. By reducing the dynamic friction coefficient of the elastic layer 14, it is possible to allow the rubber material to move in the width direction of the core body 12 during extrusion molding, and to shorten the restraint time of the rubber material by the die 80 and the core body 12. The outer diameter of the central part in the width direction is increased. Further, by increasing the dynamic friction coefficient of the core body 12 in the region where the outer diameter of the elastic layer 14 is desired to be reduced (both ends in the width direction of the elastic layer 14), the rubber material core 12 in the width direction during extrusion molding is increased. The movement of the rubber material is restricted, the restraint time of the rubber material by the die 80 and the core body 12 is increased, and the outer diameters at both ends in the width direction of the elastic layer 14 are reduced.

  In the present embodiment, the case where the dice 80 and the heating device 52 are provided separately has been described, but a configuration in which these are provided integrally may be employed.

  In the present embodiment, the crosshead die 68 is crossed with respect to the extruder 66, and the unvulcanized rubber material 15A from the extruder 66 in a direction crossing the direction in which the core 12 is guided to the crosshead die 68. However, the crosshead die 68 is not limited to the direction intersecting the extruder 66, and may be disposed along the same direction as the extruder 66.

(Image forming device, process cartridge)
Hereinafter, a case where the annular member 10 of the present embodiment is mounted on an image forming apparatus and a charging device of a process cartridge will be described.
FIG. 4 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment. FIG. 5 is a schematic configuration diagram showing a process cartridge according to the present embodiment.

  As shown in FIG. 4, the image forming apparatus 100 according to the present embodiment includes an image carrier 13, and a charging device 19 that charges the image carrier 13 and an image carrier charged by the charging device 19 around the image carrier 13. A latent image forming device 17 for exposing the body 13 to form a latent image; a developing device 16 for developing the electrostatic latent image formed by the latent image forming device 17 with toner to form a toner image; A transfer device 18 that transfers the formed toner image to the recording medium P and a cleaning device 20 that removes residual toner on the surface of the image holding member 13 after transfer are provided. Further, a fixing device 22 for fixing the toner image transferred to the recording medium P by the transfer device 18 is provided.

  In the image forming apparatus 100 according to the present embodiment, the charging device 19 includes the annular member 10 according to the present embodiment. The annular member 10 is disposed in contact with the surface of the image carrier 13 and is charged with the power supplied from a power supply device (not shown) to charge the image carrier 13.

  In the image forming apparatus 100 of the present embodiment, known configurations are conventionally applied as the respective configurations of the electrophotographic image forming apparatus except for the annular member 10 provided in the charging device 19. Hereinafter, an example of each configuration will be described.

  The image carrier 13 is not particularly limited, and a known photoreceptor can be used. An organic photoreceptor having a so-called function separation type structure in which a charge generation layer and a charge transport layer are separated is preferably used. Further, the image carrier 13 whose surface layer is covered with a protective layer having a charge transporting property and a crosslinked structure is also suitably applied. A photoreceptor composed of a siloxane-based resin, a phenol-based resin, a melamine resin, a guanamine resin, or an acrylic resin as a crosslinking component of the protective layer is also suitably applied.

  As the latent image forming device 17, for example, a laser optical system, an LED array, or the like is applied.

  For example, the developing device 16 brings a developer holding body having a developer layer formed on the surface thereof into contact with or close to the image holding body 13, and attaches toner to the electrostatic latent image on the surface of the image holding body 13. Form an image. As a developing method of the developing device 16, a developing method using a two-component developer is suitably applied as a known method. Examples of the developing method using the two-component developer include a cascade method and a magnetic brush method.

  As the transfer device 18, for example, either a non-contact transfer method such as corotron or a contact transfer method in which a conductive transfer roll is brought into contact with the image carrier 13 via the recording medium P to transfer a toner image to the recording medium P. May be adapted.

  The cleaning device 20 is a member that removes toner, paper dust, dust, and the like attached to the surface by bringing a plate-like member into direct contact with the surface of the image carrier 13, for example. As the cleaning device 20, a brush-like member, a roll-like member, or the like may be applied in addition to the plate-like member.

  An example of the fixing device 22 is a heat fixing device. The heat fixing device includes, for example, a fixing roller in which a so-called release layer is formed of a heat-resistant resin coating layer or a heat-resistant rubber coating layer on the outer peripheral surface thereof with a heater lamp for heating inside a cylindrical metal core, A pressure roller or a pressure belt that is disposed in contact with the fixing roller at a specific contact pressure and has a heat-resistant elastic body layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. . The fixing process of the unfixed toner image is performed, for example, by inserting the recording medium P on which the unfixed toner image is transferred between the fixing roller and the pressure roller or the pressure belt, and binding resin in the toner, Fixing by heat melting of additives and the like.

  The image forming apparatus 100 according to the present embodiment is not limited to the above-described configuration. For example, an intermediate transfer type image forming apparatus using an intermediate transfer member and an image forming unit that forms toner images of each color are arranged in parallel. A so-called tandem image forming apparatus may be used.

  On the other hand, as shown in FIG. 5, the process cartridge according to the present embodiment includes an opening 24A for exposure, an opening 24B for static elimination exposure, and a mounting rail 24C in the image forming apparatus 100 shown in FIG. With the housing 24 provided, the electrostatic latent image formed by the image carrier 13, the charging device 19 that charges the image carrier 13, and the latent image forming device 17 is developed with toner to form a toner image. The process cartridge 102 is configured by integrally holding the developing device 16 and the cleaning device 20 that removes residual toner on the surface of the image carrier 13 after transfer. The process cartridge 102 is detachably attached to the image forming apparatus 100 shown in FIG.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by the following Example. Unless otherwise specified, “part” means “part by mass”.

<Example 1>
(Preparation of annular member A1)
-Adjustment of the core-
Using free-cutting steel (Pb-free free-cutting steel material: SUM material), a cylindrical member having a diameter of 8 mm was adjusted by drawing and cut into a length of 330 mm. An electroless nickel plating was plated to a thickness of 8 μm. Further, as an area corresponding to both end portions in the width direction (see region 12B in FIG. 2), the following paint A was applied to an average thickness of 7 μm in each 100 mm region from both end surfaces in the width direction toward the center portion. . As a region corresponding to the central portion in the width direction (see region 12A in FIG. 2), from a position of 100 mm toward the central portion from one end surface side in the width direction, to a position of 100 mm from the other end surface side toward the central portion. The following paint A was not applied. Thus, the core A1 as the core 12 shown in FIG. 2 was adjusted.

Paint A:
・ Made by LOAD: Brand name Chemlock 204 ・ ・ ・ ・ ・ ・ 90% by mass
・ Product made by LOAD: Product name Ketjen Black EC ... 2% by mass
・ Lion: 8% by mass of xylene
The above materials were stirred and dispersed to obtain paint A.

-Adjustment of unvulcanized rubber material-
An unvulcanized rubber material A1 was prepared by kneading a mixture having the following composition using a closed mixer and an open roll.

-Composition-
Rubber raw material: 100 parts by mass (Epichlorohydrin rubber (trade name: Zeklon G-3106, manufactured by Nippon Zeon Co., Ltd.) 95 parts by mass, liquid acrylonitrile-butadiene rubber (NBR) ( Product name: N280, JSR product) 5 parts by mass)
・ Zinc oxide: 5 parts by mass
(2 types of zinc oxide: manufactured by Hakusuitec Co., Ltd.)
・ Stearic acid: 1 part by mass (Stearic acid S: manufactured by Kao Corporation)
・ Ionic conductive agent 2 parts by mass (quaternary ammonium salt, trade name: KS-555, manufactured by Kao Shimo Co., Ltd.)
・ Inorganic filler ・ Carbon black: 5 parts by mass (trade name: 3030B, manufactured by Mitsubishi Chemical Corporation)
・ Calcium carbonate ・ ・ ・ ・ 20 parts by mass (Whiteon SSB, manufactured by Shiraishi Kogyo Co., Ltd.)
・ Vulcanizing agent (sulfur: Sulfax 200S: manufactured by Tsurumi Chemical Co., Ltd.) ... 1 part by mass Shinsei Chemical Co., Ltd.)
・ Vulcanization accelerator ・ ・ ・ ・ ・ ・ 1 part by mass (tetramethylthiuram monosulfide, trade name: Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

-Production of annular member A1-
In the extrusion molding apparatus having the configuration shown in FIG. 3, a uniaxial rubber extrusion having an inner diameter (D) of 60 mm, a screw length (L) of 1200 mm, and L / D = 20 provided inside the cylinder 67 shown in FIG. Using the machine 66, the unvulcanized rubber material A1 adjusted as described above is extruded at a rotation speed of the screw 69 of 10 rpm, and the adjusted core body A1 is continuously supplied to the crosshead die 68. 68 was passed. As a result, an unvulcanized rubber layer 15 made of the unvulcanized rubber composition A1 was formed on the core A1.

  The temperature conditions of the extruder 66 were set to 80 ° C. for both the cylinder 67 and the screw 69 for the crosshead die 68 and the die 80. The die 80 used for the extruder 66 was a circle having a diameter (d) of 12.5 mm.

  Further, the unvulcanized rubber layer 15 made of the unvulcanized rubber composition A1 formed on the core A1 was vulcanized at 180 ° C. for 30 minutes in a gear oven (Espec Corp. Perfect Oven). Thereby, the annular member A1 was produced.

(Example 2)
An annular member A2 was produced under the same rubber material and extrusion conditions as in Example 1 except that the following core A2 was used instead of the core A1 used in Example 1.

-Adjustment of the core-
Using free-cutting steel (Pb-free free-cutting steel material: SUM material), a cylindrical member having a diameter of 8 mm was adjusted by drawing and cut into a length of 330 mm.
An electroless nickel plating was plated to a thickness of 8 μm. Furthermore, as a region corresponding to both end portions in the width direction (see region 12B in FIG. 2), the coating A used in Example 1 is not applied to each region of 100 mm from both end surfaces in the width direction toward the center portion. , Sandblasting was performed. The sandblast treatment was performed using an abrasive (alumina) having a particle size of 0.1 mm.

  And as a region corresponding to the central portion in the width direction of the plated cylindrical member (see region 12A in FIG. 2), from the position of 100 mm from the one end surface side in the width direction toward the central portion, the width direction The coating material A used in Example 1 was applied to an average thickness of 7 μm from the other end surface side to the center portion toward 100 mm. Thus, the core body A2 as the core body 12 shown in FIG. 2 was adjusted.

(Example 3)
An annular member A3 was produced under the same rubber material and extrusion conditions as in Example 1 except that the following core A3 was used instead of the core A1 used in Example 1.

-Adjustment of the core-
Using free-cutting steel (Pb-free free-cutting steel material: SUM material), a cylindrical member having a diameter of 8 mm was adjusted by drawing and cut into a length of 330 mm.
An electroless nickel plating was plated to a thickness of 8 μm. Furthermore, as a region corresponding to both end portions in the width direction (see region 12B in FIG. 2), the coating A was applied to an average thickness of 7 μm in each region of 100 mm from both end surfaces in the width direction toward the center portion. And as a region corresponding to the central portion in the width direction of the plated cylindrical member (see region 12A in FIG. 2), from the position of 100 mm from the one end surface side in the width direction toward the central portion, the width direction Silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd., trade name: KF96) was applied to an average thickness of 1 μm from the other end surface to a central portion of 100 mm. Thereby, the core A3 as the core 12 shown in FIG. 2 was adjusted.

(Comparative Example 1)
An annular member B1 was produced under the same rubber material and extrusion conditions as in Example 1 except that the following core B1 was used instead of the core A1 used in Example 1.

-Adjustment of the core-
Using free-cutting steel (Pb-free free-cutting steel material: SUM material), a cylindrical member having a diameter of 8 mm was adjusted by drawing and cut into a length of 330 mm.
An electroless nickel plating was plated to a thickness of 8 μm. No coating was applied to the plated cylindrical member.

(Comparative Example 2)
An annular member B2 was produced under the same rubber material and extrusion conditions as in Example 1 except that the following core B2 was used instead of the core A1 used in Example 1.

-Adjustment of the core-
Using free-cutting steel (Pb-free free-cutting steel material: SUM material), a cylindrical member having a diameter of 8 mm was adjusted by drawing and cut into a length of 330 mm.
An electroless nickel plating was plated to a thickness of 8 μm. Then, no paint was applied as a region where the elastic layer 14 was not formed in each region of 10 mm from both end faces in the width direction of the plated cylindrical member toward the center. Nothing was applied from the position of 10 mm toward the center from each of the both end faces in the width direction of the plated cylindrical member, and further to the region of 100 mm toward the center. And in the area | region from the position of 100 mm toward the center part from the one end surface side of the width direction to the position of 100 mm toward the center part from the other end surface side, the coating material A prepared in Example 1 has an average thickness of 7 μm. It was applied to. In this way, the core body B2 was adjusted.

<Evaluation>
[Measurement of dynamic friction coefficient of core]
About the core in each cyclic | annular member produced in the Example and the comparative example, the core produced in each of an Example and a comparative example using the surface dynamic friction coefficient measuring machine HEIDON (14) by Shinto Kagaku Co., Ltd. An area from the position of 10 mm to the position of 100 mm from both end faces in the width direction toward the center is defined as an area corresponding to “both ends in the width direction of the core”, and the average dynamic friction coefficient of this area was measured. . The measurement results are shown in Table 1.

  The average dynamic friction coefficient at both ends of the core body in the width direction was measured for each of a total of three locations every 20 mm in the width direction for the area corresponding to the both ends of the core body, Obtained by determining the value.

  Moreover, the area | region from the position of 100 mm toward the center part from the one end surface side of the width direction of the core body produced in each of an Example and a comparative example to the position of 165 mm toward the center part from the other end surface side of the width direction As a region corresponding to “the central portion in the width direction of the core”, the dynamic friction coefficient of this region was measured. The measurement results are shown in Table 1.

  The average dynamic friction coefficient of the central portion in the width direction of the core is determined by measuring the dynamic friction coefficient for each of a total of three locations every 20 mm in the width direction in the region corresponding to the central portion of the core. Obtained by determining the value.

  In addition, the measurement of the dynamic friction coefficient at each measurement position is prepared in detail by preparing a test piece (50 mm × 50 mm, thickness 2 mm) of an elastic layer formed on each core in each of the examples and comparative examples. Using a dynamic friction coefficient measuring machine, the surface of the core and the test piece are brought into surface contact, the test piece is fixed, the core is moved, temperature 22 ° C., humidity 55% RH, moving speed 5 mm / sec, The measurement was performed under a load of 500 g.

  For the elastic layer test piece, a rubber compound having the same composition as that of the elastic layer 14 was formed by vulcanization treatment at 180 ° C. for 30 minutes using a vulcanizing press and a mold, and the rubber sheet was cut out from the rubber sheet. .

[Measurement of the minimum value of the dynamic friction coefficient at the center in the width direction of the core]
The lowest value among the measurement results of the dynamic friction coefficient in the region corresponding to the central portion in the width direction of the core body produced in each of the examples and the comparative examples obtained by the measurement of the dynamic friction coefficient of the core body. Obtained by asking. The results are shown in Table 1.

[Measurement of the maximum value of the dynamic friction coefficient at both ends in the width direction of the core]
The highest value among the measurement results of the dynamic friction coefficient in the region corresponding to both ends in the width direction of the core bodies produced in each of the examples and the comparative examples obtained by the measurement of the dynamic friction coefficient of the core body. Obtained by asking. The results are shown in Table 1.

[Measurement of the ratio of the maximum value of the friction coefficient at both ends in the width direction of the core to the minimum value of the coefficient of friction at the center in the width direction of the core]
The maximum value obtained by measuring the maximum value of the dynamic friction coefficient at both ends in the direction of the core body, relative to the minimum value obtained by measuring the minimum value of the dynamic friction coefficient at the center part in the width direction of the core body. Was obtained by calculating the ratio. The results are shown in Table 1.

(Measurement of the outer diameter of the central part in the width direction of the elastic layer)
For each of the annular members produced in the above-mentioned examples and comparative examples, the position in the center in the width direction (half the length in the width direction of the elastic layer) is defined as “the center in the width direction of the elastic layer”. The outer diameter was measured using a laser outer diameter measuring instrument (Asaka Riken).

[Measurement of outer diameter of both ends of elastic layer in width direction]
About each of the annular members produced in the above-mentioned examples and comparative examples, the outer diameter is defined as a position of 30 mm from the both end surfaces in the width direction of the elastic layer toward the center portion as “both ends in the width direction of the elastic layer”. The measurement was performed using a laser outer diameter measuring instrument (Asaka Riken).

[Confirmation of elastic layer shape]
The shape of the elastic layer of the annular member produced in the above examples and comparative examples was confirmed visually. The evaluation results are shown in Table 1.
In Table 1, “crown shape” indicates a shape in which the outer diameter of the central portion in the width direction is larger than the outer diameters of both end portions in the width direction. In Table 1, the “reverse crown shape” indicates a shape in which the outer diameter of the central portion in the width direction is smaller than the outer diameters of both end portions in the width direction. Further, in Table 1, “columnar shape” refers to a shape in which the ratio of the outer diameters at both ends in the width direction to the outer diameter at the center in the width direction is 0.995 or more and 1.005 or less.

[Confirmation of the magnitude relationship between the residual strain at the center in the width direction of the elastic layer and the residual strain at both ends in the width direction]
The initial shape of the produced rubber roll was measured in advance in the axial direction with a laser outer diameter measuring instrument (manufactured by Asaka Riken), and after removing the elastic layer where the residual strain was measured, the elasticity remaining on the core body side The same part of the layer is again measured for straightness in the axial direction, and the degree to which the elastic layer of the cut end surface is bounced (outer diameter growth by releasing the constraint) is obtained. The measurement environment was a temperature of 22 ° C. and a humidity of 55% RH. The measurement results are shown in Table 1.

[Evaluation of shape retention of elastic layer]
A cylindrical member made of stainless steel (Φ38 mm × length 350 mm) was pressed against the outer peripheral surface of each of the annular members produced in the above examples and comparative examples with a set load of 10 N, temperature 40 ° C., humidity 95% It was left in an RH environment for 72 hours. Then, after solving from this pressure, the cross-sectional shape of each position of the elastic layer in the width direction and the both ends of the elastic layer in the width direction are measured, and the remaining degree of deformation with respect to the shape before applying the nip load is confirmed. Went. And the retainability of the crown shape of the elastic layer was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.

-Evaluation criteria-
◯: Remaining deformations at the center and both ends in the elastic layer width direction are both 15 μm or less.
(Triangle | delta): It is 15 micrometers or less of residual deformation of the elastic layer width direction center part or both ends, and the other is 20 micrometers or less.
X: Residual deformation of each of the central portion and both end portions in the elastic layer width direction is 15 μm or more, or one exceeds 20 μm.

  As shown in Table 1, the annular member produced in the example was compared with the annular member produced in the comparative example, even after the pressure was applied from the outer peripheral side. As a result, it was found that when opened, the shape of the elastic layer was excellent.

DESCRIPTION OF SYMBOLS 10 cyclic | annular member, 12 core body, 13 image holding body, 14 elastic layer, 19 charging device, 100 image forming apparatus

Claims (6)

The core,
An elastic layer provided on the core body, wherein the outer diameter of the central portion in the width direction is larger than the outer diameter of both end portions in the width direction, and the residual strain in the central portion in the width direction is smaller than both end portions in the width direction;
Equipped with a,
An annular member having a dynamic friction coefficient at a center portion in the width direction of the core body lower than both end portions in the width direction . 2. The annular member according to claim 1, wherein a minimum value of a dynamic friction coefficient in a central portion in a width direction of the core body is 0.1 or more and 0.8 or less. A charging device with an annular member according to claim 1 or claim 2. An image carrier,
A charging device for charging the image carrier;
A latent image forming device that forms an electrostatic latent image on the image carrier charged by the charging device;
A developing device for developing the electrostatic latent image on the image carrier with toner;
A transfer device for transferring a toner image formed on the image carrier by the developing device to a transfer target;
Have
3. An image forming apparatus, wherein at least one of the charging device, the developing device, and the transfer device includes the annular member according to claim 1 or 2 .   The manufacturing method of the annular member of Claim 1 provided with the process of providing an elastic layer by extrusion molding on the core body whose dynamic friction coefficient in the center part of the width direction is lower than the both ends of the width direction. The method for manufacturing an annular member according to claim 5 , wherein a minimum value of a dynamic friction coefficient in a central portion in the width direction of the core body is 0.1 or more and 0.8 or less.

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