WO2016002172A1 - Charging roller, and image formation device - Google Patents

Charging roller, and image formation device Download PDF

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Publication number
WO2016002172A1
WO2016002172A1 PCT/JP2015/003204 JP2015003204W WO2016002172A1 WO 2016002172 A1 WO2016002172 A1 WO 2016002172A1 JP 2015003204 W JP2015003204 W JP 2015003204W WO 2016002172 A1 WO2016002172 A1 WO 2016002172A1
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WIPO (PCT)
Prior art keywords
layer
charging roller
shaft
base layer
resistance value
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PCT/JP2015/003204
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French (fr)
Japanese (ja)
Inventor
代治郎 白倉
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株式会社ブリヂストン
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Publication of WO2016002172A1 publication Critical patent/WO2016002172A1/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices

Definitions

  • the present invention relates to a charging roller and an image forming apparatus.
  • an image forming apparatus such as a copying machine or a printer
  • the surface of a charged body such as a photoconductor is uniformly charged, and an image is projected from the optical system onto the charged body, and a portion exposed to light
  • An electrostatic latent image is obtained by an electrostatic latent image forming process in which a latent image is formed by erasing the charge of the toner, and then the toner image is formed by toner adhesion, the toner image is transferred to a recording medium such as paper, and the like.
  • the method of printing is taken.
  • the surface of the charged body is charged by a contact method in which a charging member to which a voltage is applied is brought into contact with the charged body.
  • a charging roller as shown in Patent Document 1 is used as a charging member for charging an object to be charged, and a charging roller shaft and a radially outer roller of the charging roller are used.
  • a current is passed between the surface of the charging roller and a voltage is applied uniformly to the surface of the charging roller in the axial direction to charge the surface of the member to be charged.
  • the present inventor has conducted intensive research to obtain a charging roller capable of sufficiently uniformly charging a member to be charged.
  • the inventor has found that the conventional charging roller cannot apply a voltage to the surface thereof sufficiently uniformly in the axial direction, and the cause is formed on the outer peripheral surface of the shaft of the charging roller.
  • the base layer has its conductivity in the axial direction, in other words, the resistance value may not be sufficiently uniform in the axial direction.
  • the inventor can reduce the resistance value of the charging roller by reducing the resistance value of the intermediate layer itself formed radially outside the base layer even if the resistance value in the axial direction of the base layer is not sufficiently uniform.
  • the present invention has been completed by finding that a voltage can be applied to the surface sufficiently uniformly in the axial direction.
  • the charging roller of the present invention is a charging roller that charges a member to be charged by applying a voltage to the member to be charged, the shaft, a base layer formed on the outer peripheral surface of the shaft, An intermediate layer formed radially outside the base layer and a surface layer formed radially outside the intermediate layer and forming the outer surface of the charging roller are sequentially provided, and the intermediate layer is carbon as a conductive agent.
  • the resistance value R2 between the surface and the shaft, R2 ⁇ R1 It is characterized by satisfying the relationship. According to the charging roller of the present invention, the charged body can be charged sufficiently uniformly.
  • the above-mentioned “conductive agent in the lower layer containing only carbon black as the conductive agent” means “one that can lower the resistance value of the added material by adding”.
  • the resistance values R1 and R2 are 1.05 ⁇ R1 / R2 It is preferable to satisfy the relationship. According to this configuration, it is possible to more uniformly charge the charged body.
  • the adhesive layer has a resistance value Rm of 4 M ⁇ or less. According to this configuration, the charged body can be more sufficiently uniformly charged.
  • the image forming apparatus of the present invention includes the above-described charging roller. According to the image forming apparatus of the present invention, the occurrence of image defects can be suppressed.
  • the present invention it is possible to provide a charging roller capable of sufficiently uniformly charging an object to be charged.
  • FIG. 3 is a cross-sectional view in a direction orthogonal to the axial direction of the charging roller, showing an embodiment of the charging roller of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing the operation effect of the charging roller shown in FIG. 1 in a state where a voltage is applied to the charging roller and brought into contact with a photosensitive member.
  • (A) is a figure which shows the measuring method of the resistance value between the surface of each layer formed in the outer peripheral side of the shaft of a charging roller, and a shaft.
  • (B) is a figure which shows the measuring method of the resistance value of each layer of a charging roller.
  • 1 is a partial cross-sectional view showing an embodiment of an image forming apparatus of the present invention.
  • FIG. 1 is a cross-sectional view showing a structure of an example of the charging roller of the present invention in a direction orthogonal to the axial direction of the charging roller.
  • the illustrated charging roller 1 can be used in an image forming apparatus such as a copying machine or a printer, and is in contact with or close to a charged body such as a photoconductor in the image forming apparatus (a gap of several tens of ⁇ m). The charged body is charged by applying a voltage between the charged body and the charged body.
  • the charging roller 1 includes at least a shaft 2, a base layer 3 formed on the outer peripheral surface of the shaft 2, and an intermediate layer formed radially outside the base layer 3. 4.
  • the base layer 3 on the outer peripheral surface of the shaft 2, from the radially inner side to the outer side, the base layer 3, the adhesive layer 41 as the intermediate layer 4, the first lower layer 42 and the second lower layer 43, and A surface layer 5 is formed.
  • the intermediate layer 4 refers to a layer provided between the base layer 3 and the surface layer 5, such as the adhesive layer 41, the first lower layer 42, and the second lower layer 43. "May indicate at least one of the adhesive layer 41, the first lower layer 42, the second lower layer 43, or all of the layers.
  • the shaft 2 serves as the axis of the charging roller 1 and is not limited as long as it has good conductivity.
  • the shaft 2 can be made of metal such as iron, stainless steel, and aluminum.
  • the shape of the shaft 2 is not limited as long as it has sufficient rigidity.
  • the shaft 2 can be a solid body or a cylindrical body in which the inside is hollowed.
  • the shaft 2 is preferably a solid body from the viewpoint of rigidity.
  • the outer diameter of the shaft 2 is not limited, but can be 4 to 10 mm, for example, and the increase in weight can be suppressed while ensuring the rigidity of the charging roller 1.
  • the base layer 3 is a layer having electrical conductivity and elasticity formed on the outer peripheral surface of the shaft 2, and absorbs the pressure when the charging roller 1 comes into contact with the member to be charged and charges the current from the shaft 2. This is a layer for energizing the outer surface of the roller 1.
  • the base layer 3 can be formed from a material such as rubber, resin, or foamed material thereof.
  • the rubber or resin is not limited, and examples thereof include polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene.
  • One or more selected from rubber, styrene-butylene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber and the like can be used.
  • foamed polyurethane is preferable from the viewpoint of adhesion to an object to be charged.
  • the base layer 3 is added with a conductive agent such as an ionic conductive agent or an electronic conductive agent in order to have conductivity.
  • a conductive agent such as an ionic conductive agent or an electronic conductive agent in order to have conductivity.
  • the conductive agent include, but are not limited to, for example, ionic conductive agents include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, and octadecyltrimethylammonium (for example, Stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium and the like and ammonium with perchloric acid, chloric acid, hydrochloric acid, bromic acid, iodic acid, borofluoric acid, sulfuric acid, ethyl sulfuric acid, carboxy
  • alkaline metals and alkaline earth metals such as lithium, sodium, potassium, calcium, magnesium and perchloric acid, chloric acid, hydrochloric acid, bromic acid, iodic acid, borofluoric acid, Trifluoromethyl sulfate, alkali metal salts or alkaline earth metal salts of sulfonic acid; and the like.
  • Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; for ink subjected to oxidation treatment Examples thereof include carbon, pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium. These conductive agents may be used alone or in combination of two or more.
  • an optional additive such as an antioxidant such as phenol or phenylamine, a low friction agent, a charge adjusting agent, a foaming agent, a surfactant, a filler, or the like is added to the base layer 3. be able to.
  • the formation of the base layer 3 is not limited, but, for example, the above-mentioned rubber or resin is mixed with the above conductive agent and additive, and then the mixture is injected into a mold in which the shaft 2 is disposed. This can be done by curing.
  • the rubber or resin is foamed in advance, the above mixture can be foamed using a method such as a mechanical floss method, a water foam method, or a foaming agent floss method.
  • the adhesive layer 41 is located between the base layer 3 and the first lower layer 42, and is provided to adhere each layer and improve adhesion.
  • the adhesive layer 41 is not limited, but can be formed from materials such as polyamide (such as nylon), polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, polyurethane, epoxy resin, and urea resin.
  • polyamide such as nylon
  • polyester urethane-modified acrylic resin
  • acrylic resin acrylic resin
  • polyurethane epoxy resin
  • urea resin urethane resin
  • a conductive agent or an additive that can be added to the base layer 3 can be added to the adhesive layer 41.
  • the thickness of the adhesive layer 41 is preferably 5 to 40 ⁇ m in order to ensure adhesion between the base layer 3 and the first lower layer 42.
  • the first lower layer 42 and the second lower layer 43 are provided for adjusting the resistance.
  • Each lower layer 42, 43 is formed of a material such as, but not limited to, polyamide (such as nylon), polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, polyurethane, urea resin, or fluororesin. be able to.
  • the first lower layer 42 and the second lower layer 43 can be made of the same or different materials.
  • an additive that can be added to the base layer 3 can be added to each of the lower layers 42 and 43.
  • each lower layer 42, 43 contains only carbon black as a conductive agent.
  • the ionic conductive agent when used as the conductive agent, the ionic conductive agent may be polarized when the charging roller is used, and the ionic conductive agent may bleed out on the surface of the charging roller, which may cause contamination.
  • the lower layers 42 and 43 contain only carbon black as a conductive agent, the above-mentioned contamination can be prevented while imparting conductivity to the charging roller 1.
  • the lower layer is composed of two layers of one first lower layer 42 and one second lower layer 43, depending on the performance intended for the charging roller 1 or its manufacture.
  • the lower layer can be composed of one layer or three or more layers made of the same or different materials.
  • the surface layer 5 is a layer that forms the outer surface of the charging roller 1 and is in contact with the member to be charged when a voltage is applied to the member to be charged such as a photosensitive member.
  • the surface layer 5 is not limited, but can be formed using the same material as the lower layer. Note that a material suitable for the purpose of preventing toner adhesion to the surface layer 5 and ensuring surface smoothness can be used.
  • a conductive agent or additive that can be added to the base layer 3 can be added to the surface layer 5.
  • the surface of the charging roller 1 has irregularities, for example, toner in the recesses can cause image defects. Therefore, the surface of the surface layer 5 is preferably smooth.
  • the average roughness Rz is preferably 30 ⁇ m or less.
  • the formation of the adhesive layer 41, the lower layers 42 and 43, and the surface layer 5 is not limited, but a paint containing the above materials for forming each layer is prepared, and the paint is used, for example, by dipping or It can be performed by applying by a spray method.
  • the base layer formed on the outer peripheral surface of the shaft of the charging roller may not have a sufficiently uniform resistance value in the axial direction. It was found that the voltage could not be applied to the surface of the roller sufficiently uniformly in the axial direction.
  • the resistance value of the base layer does not become sufficiently uniform in the axial direction, for example, as described above, the base layer is manufactured by injecting rubber, resin, or a foam thereof into a mold and curing it. Occurs when manufactured. In such a case, the resistance value on one end side in the axial direction tends to be higher than the resistance value on the other end side in the axial direction.
  • the resistance value R1 (hereinafter referred to as “the shaft 2”) between the surface of the base layer 3 and the shaft 2 in at least one position in the axial direction of the laminated body in which the base layer 3 is formed on the shaft 2. Also, the resistance between the surface of the adhesive layer 41 and the shaft 2 at the position of the laminate in which the base layer 3 to the adhesive layer 41 are formed on the shaft 2.
  • Value R2 (hereinafter referred to as “adhesion layer-shaft resistance value R2”) R2 ⁇ R1 Satisfy the relationship.
  • the base layer-shaft resistance value R1 and the adhesive layer-shaft resistance value R2 are in the above relationship.
  • a voltage can be applied to the surface of the charging roller 1 in a sufficiently uniform manner in the axial direction. Therefore, the charged body can be charged sufficiently uniformly and obtained by an image forming apparatus having the charging roller 1. It is possible to suppress the occurrence of defects in the image to be produced.
  • the charging roller 1 when used in an image forming apparatus, an electric current flows in the charging roller 1 as follows. It is considered that the voltage can be applied sufficiently uniformly. That is, the base layer-shaft resistance R1 is not sufficiently uniform in the axial direction. For example, at least one position of the base layer 3 in the axial direction, in the illustrated example, one end side in the axial direction of the base layer 3 (FIG. 2). In some cases, the resistance value R1 between the base layer and the shaft on the left side is higher than the resistance value R1 ′ between the base layer and the shaft on the other end side (the right side in FIG. 2).
  • FIG. 2 is a diagram schematically showing the operation and effect of the charging roller, which is different from each dimension in the cross-sectional view of the charging roller in FIG.
  • the “base layer-shaft resistance value” is the value of at least one position in the axial direction of the laminated body in which the base layer 3 is formed on the outer peripheral surface of the shaft 2.
  • the resistance value measured by attaching one electrode E of the resistance measuring device D to the surface of the base layer 3 and attaching the other electrode E to the shaft 2 is indicated.
  • the “resistance value between the adhesive layer and the shaft” is the same for the laminated body in which the base layer 3 to the adhesive layer 41 are formed on the outer peripheral surface of the shaft 2 at at least one position in the axial direction of the laminated body.
  • the resistance value measured between the surface of the adhesive layer 41 and the shaft 2 is indicated.
  • the resistance value Rm of the adhesive layer 41 is preferably 4 M ⁇ or less. According to this configuration, it is possible to more effectively suppress the occurrence of image defects. From the same viewpoint, the resistance value Rm is more preferably 1.0 M ⁇ or less.
  • the “resistance value” of each layer is such that the layer to be measured is formed on a cylindrical rod A made of resin having the same outer diameter as the inner diameter of the layer to be measured. It is assumed that measurement is performed in a state where the two electrodes E of the resistance measuring device D are separated by 5 mm.
  • the resistance value of the base layer 3 is preferably 0.001 to 0.1 M ⁇ .
  • the object to be charged can be sufficiently charged.
  • the base layer-shaft resistance value R1 is larger than the adhesive layer-shaft resistance value R2, and further, the adhesive layer-shaft resistance value in the axial direction of the adhesive layer 41.
  • the base layer 3 and the adhesive layer 41 may contain a conductive agent as follows. preferable. Since the base layer 3 can suppress image defects as a conductive agent in a high temperature and high humidity environment, the base layer 3 preferably contains an ionic conductive agent.
  • the blending amount of the conductive agent is preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the base layer, and more preferably 0.1 to 0.2 part by weight with respect to 100 parts by weight of the base layer. It is.
  • the adhesive layer 41 preferably contains only carbon black as a conductive agent from the viewpoint of suppressing bleeding out.
  • the blending amount of the conductive agent is preferably 45 to 55 parts by weight with respect to 100 parts by weight of the resin component of the adhesive layer 41, and more preferably 50 parts by weight with respect to 100 parts by weight of the resin component of the adhesive layer 41.
  • the ratio of parts In particular, in order to set the resistance Rm to 4 M ⁇ or less, it is preferable to add 45 parts by weight or more of a conductive agent to 100 parts by weight of the resin component of the adhesive layer 41.
  • the image forming apparatus of the present invention includes the above-described charging roller.
  • the image forming apparatus of the present invention is not particularly limited except that it includes the above-described charging roller, and can have a known configuration.
  • FIG. 4 is a partial sectional view showing an embodiment of the image forming apparatus 6 of the present invention.
  • the image forming apparatus 6 in the illustrated example supplies a photosensitive member 7 holding an electrostatic latent image, a charging roller 1 located near the photosensitive member 7 (upward in the drawing) for charging the photosensitive member 7, and toner.
  • the image forming apparatus 6 of the present invention can further include a known component (not shown) that is normally used in the image layer forming apparatus.
  • the charging roller 1 is brought into contact with the photoreceptor 7, and a voltage is applied between the photoreceptor 7 and the charging roller 1 to charge the photoreceptor 7 to a constant potential. Thereafter, an electrostatic latent image is formed on the photoconductor 7 by an exposure machine (not shown). Next, the photoreceptor 7, the toner supply roller 8, and the developing roller 9 rotate in the direction of the arrow in the drawing, so that the toner on the toner supply roller 8 is sent to the photoreceptor 7 through the developing roller 9. .
  • the toner on the developing roller 9 is adjusted to a uniform thin layer by the stratifying blade 10 and rotates while the developing roller 9 and the photoconductor 7 are in contact with each other.
  • the latent image becomes visible.
  • the toner adhering to the latent image is transferred to a recording medium such as paper by the transfer roller 11, and the toner remaining on the photoreceptor 7 after the transfer is removed by the cleaning roller 12.
  • a recording medium such as paper
  • the cleaning roller 12 the toner remaining on the photoreceptor 7 after the transfer is removed by the cleaning roller 12.
  • the charging roller and the image forming apparatus of the present invention are not limited to the above example, and can be appropriately modified.
  • the charging roller of Example 1 includes a shaft (made of free-cutting steel), a base layer (material: polyurethane, conductive agent: ionic conductive agent (manufacturer name: Nippon Carlit Co., Ltd., trade name: PEL-46).
  • the resistance value between the shafts in the table is measured by measuring the width of the resistance measuring instrument D at a position spaced 12.5 mm inward in the axial direction from one end or the other end of the layer to be measured.
  • the resistance value when the voltage of 200 V was applied between the shaft and the shaft was measured with a resistance measuring device D so that the center of the electrode E in the width direction of 5 mm was positioned.
  • the image forming apparatus using the charging roller of each of Examples 1 to 4 and Comparative Examples 1 and 2 is left in a high temperature and high humidity (30 ° C., 85%) environment for one day, and then the high temperature and high humidity environment.
  • Table 1 shows the result of sensory evaluation on whether or not a defect (fogging) occurs in an image after printing 20,000 sheets.
  • the resistance value of the adhesive layer when the conductive agent was contained in the adhesive layer of the charging roller in the blending amount shown in Table 2 was investigated.
  • the resistance value is measured by forming an adhesive layer on a resin cylindrical rod A having the same outer diameter as that of the adhesive layer, and connecting two electrodes E having a width of 5 mm. It measured using resistance measuring device D in the state spaced apart by 5 mm.
  • the film thickness of the adhesive layer is 9 ⁇ m.
  • the surface of the charging roller can be applied with a sufficiently uniform voltage in the axial direction on the surface of the charging roller. It can be seen that the amount of the conductive agent to be added is 45 parts by weight or more, and that the resistance value becomes 4 M ⁇ or less when such an amount of the conductive agent is added to the adhesive layer.
  • the present invention it is possible to provide a charging roller capable of sufficiently uniformly charging an object to be charged.
  • Charging roller 2 Shaft 3: Base layer 4: Intermediate layer 41: Adhesive layer (intermediate layer) 42: 1st lower layer (intermediate layer) 43: Second lower layer (intermediate layer) 5: Surface layer 6: Image forming apparatus 7: Photoconductor 8: Toner supply roller 9: Developing roller 10: Layering blade 11: Transfer roller 12: Cleaning roller A: Resin cylindrical rod D: Resistance measuring device E: Electrode

Abstract

The present invention provides a charging roller capable of uniformly and sufficiently charging an object to be charged. Furthermore, the purpose of the present invention is to provide an image formation device in which the occurrence of image defects is suppressed. This charging roller is characterized by being sequentially provided with: a shaft; a base layer formed on the outer peripheral surface of the shaft; an intermediate layer formed further radially outward than the base layer; and a surface layer forming the outer surface of the charging roller. The charging roller is further characterized in that: the intermediate layer comprises a lower layer including only carbon black as a conductive agent, and an adhesive layer which is positioned between the lower layer and the base layer, and which bonds the respective layers together; and the resistance value (R1) between the shaft and the surface of the base layer, at at least one position in the axial direction in a stacked body obtained by forming the base layer on the shaft, and the resistance value (R2) between the shaft and the surface of the adhesive layer, at the aforementioned position in a stacked body obtained by forming, on the shaft, the layers spanning from the base layer to the adhesive layer, satisfy the relationship R2<R1.

Description

帯電ローラおよび画像形成装置Charging roller and image forming apparatus
　本発明は、帯電ローラおよび画像形成装置に関する。 The present invention relates to a charging roller and an image forming apparatus.
　従来、複写機、プリンター等の画像形成装置では、まず、感光体等の被帯電体の表面を一様に帯電させ、この被帯電体に光学系から映像を投射して、光の当たった部分の帯電を消去することによって潜像を形成する静電潜像形成プロセスにより静電潜像を得、次いで、トナーの付着によるトナー像の形成、紙等の記録媒体へのトナー像の転写等により、プリントする方法がとられている。 Conventionally, in an image forming apparatus such as a copying machine or a printer, first, the surface of a charged body such as a photoconductor is uniformly charged, and an image is projected from the optical system onto the charged body, and a portion exposed to light An electrostatic latent image is obtained by an electrostatic latent image forming process in which a latent image is formed by erasing the charge of the toner, and then the toner image is formed by toner adhesion, the toner image is transferred to a recording medium such as paper, and the like. The method of printing is taken.
　ここで、上記の画像形成装置における静電潜像形成プロセスにおいて、被帯電体の表面の帯電は、電圧を印加した帯電用部材を被帯電体に当接させることにより行う接触方式で行われることがある。具体的には、この接触方式では、被帯電体を帯電させるための帯電用部材として例えば特許文献１に示すような帯電ローラが用いられており、帯電ローラのシャフトとその径方向外側のローラの表面との間で電流を流して帯電ローラの表面に、その軸方向に均一に電圧を印加して被帯電体の表面を帯電させている。 Here, in the electrostatic latent image forming process in the image forming apparatus, the surface of the charged body is charged by a contact method in which a charging member to which a voltage is applied is brought into contact with the charged body. There is. Specifically, in this contact method, for example, a charging roller as shown in Patent Document 1 is used as a charging member for charging an object to be charged, and a charging roller shaft and a radially outer roller of the charging roller are used. A current is passed between the surface of the charging roller and a voltage is applied uniformly to the surface of the charging roller in the axial direction to charge the surface of the member to be charged.
特開２００２－２２９３０５号公報JP 2002-229305 A
　ところで、近年の画像形成装置の高性能化に伴って、被帯電体の表面への帯電の均一性が高度に要求されており、その帯電が十分に均一でなければ、プリントされる画像に不良が発生する虞があった。したがって、画像形成装置によってプリントされる画像に不良が発生するのをより十分に抑制するため、被帯電体への帯電を十分に均一に行える帯電ローラが求められている。 By the way, with the recent improvement in performance of image forming apparatuses, there has been a high demand for uniformity of charging on the surface of the object to be charged. If the charging is not sufficiently uniform, the printed image is defective. There was a risk of occurrence. Therefore, in order to more sufficiently suppress the occurrence of defects in the image printed by the image forming apparatus, a charging roller capable of sufficiently uniformly charging the charged body is desired.
　そこで、本発明は、被帯電体への帯電を十分に均一に行うことができる帯電ローラを提供することを目的とする。また、本発明は、画像不良の発生を抑制させた画像形成装置を提供することを目的とする。 Therefore, an object of the present invention is to provide a charging roller capable of sufficiently uniformly charging an object to be charged. Another object of the present invention is to provide an image forming apparatus in which the occurrence of image defects is suppressed.
　本発明者は、被帯電体への帯電を十分に均一に行うことができる帯電ローラを得るため鋭意研究を行った。そして、発明者は、従来の帯電ローラでは、その表面に、軸方向で十分に均一に電圧を印加できていないことを見出し、さらにその原因は、帯電ローラのシャフトの外周面上に形成される基層が、軸方向でその導電性、換言すれば、軸方向で抵抗値が十分に均一にならないことがあるためであることを見出した。そして、発明者は、基層の軸方向での抵抗値が十分に均一になっていなくても、基層よりも径方向外側に形成される中間層自体の抵抗値を小さくすることにより、帯電ローラの表面に、軸方向で十分に均一に電圧を印加することができることを見出して本発明を完成させた。 The present inventor has conducted intensive research to obtain a charging roller capable of sufficiently uniformly charging a member to be charged. The inventor has found that the conventional charging roller cannot apply a voltage to the surface thereof sufficiently uniformly in the axial direction, and the cause is formed on the outer peripheral surface of the shaft of the charging roller. It has been found that the base layer has its conductivity in the axial direction, in other words, the resistance value may not be sufficiently uniform in the axial direction. The inventor can reduce the resistance value of the charging roller by reducing the resistance value of the intermediate layer itself formed radially outside the base layer even if the resistance value in the axial direction of the base layer is not sufficiently uniform. The present invention has been completed by finding that a voltage can be applied to the surface sufficiently uniformly in the axial direction.
　本発明の帯電ローラは、被帯電体との間に電圧を印加することにより当該被帯電体を帯電させる帯電ローラであって、シャフトと、当該シャフトの外周面上に形成された基層と、当該基層よりも径方向外側に形成された中間層と、当該中間層の径方向外側に形成され、前記帯電ローラの外表面を形成する表面層とを順次備え、前記中間層が、導電剤としてカーボンブラックのみを含有する下層と、当該下層および前記基層の間に位置して当該下層および当該基層を接着させる接着層とからなり、前記シャフトに前記基層が形成された積層体の、軸方向で少なくとも１つの位置における当該基層の表面と当該シャフトとの間の抵抗値Ｒ１、および、前記シャフトに前記基層から前記接着層までが形成された積層体の前記位置における、当該接着層の表面と当該シャフトとの間の抵抗値Ｒ２が、
Ｒ２＜Ｒ１
の関係を満たすことを特徴とする。
　この発明の帯電ローラによれば、被帯電体への帯電を十分に均一に行うことができる。
　なお、ここで、上記の「導電剤としてカーボンブラックのみを含有する下層」における導電剤とは、「添加することにより添加された材料の抵抗値を下げることができるもの」を意味する。 The charging roller of the present invention is a charging roller that charges a member to be charged by applying a voltage to the member to be charged, the shaft, a base layer formed on the outer peripheral surface of the shaft, An intermediate layer formed radially outside the base layer and a surface layer formed radially outside the intermediate layer and forming the outer surface of the charging roller are sequentially provided, and the intermediate layer is carbon as a conductive agent. A lower layer containing only black, and an adhesive layer that is located between the lower layer and the base layer and adheres the lower layer and the base layer, and at least in the axial direction of the laminate in which the base layer is formed on the shaft. The resistance R1 between the surface of the base layer and the shaft at one position, and the adhesion at the position of the laminate in which the base to the adhesive layer are formed on the shaft. The resistance value R2 between the surface and the shaft,
R2 <R1
It is characterized by satisfying the relationship.
According to the charging roller of the present invention, the charged body can be charged sufficiently uniformly.
Here, the above-mentioned “conductive agent in the lower layer containing only carbon black as the conductive agent” means “one that can lower the resistance value of the added material by adding”.
　ここで、本発明の帯電ローラでは、前記抵抗値Ｒ１およびＲ２が、
１．０５≦Ｒ１／Ｒ２
の関係を満たすことが好ましい。
　この構成によれば、被帯電体への帯電をより十分に均一に行うことができる。 Here, in the charging roller of the present invention, the resistance values R1 and R2 are
1.05 ≦ R1 / R2
It is preferable to satisfy the relationship.
According to this configuration, it is possible to more uniformly charge the charged body.
　また、本発明の帯電ローラでは、前記接着層の抵抗値Ｒｍが、４ＭΩ以下であることが好ましい。
　この構成によれば、被帯電体への帯電をさらに十分に均一に行うことができる。 In the charging roller of the present invention, it is preferable that the adhesive layer has a resistance value Rm of 4 MΩ or less.
According to this configuration, the charged body can be more sufficiently uniformly charged.
　本発明の画像形成装置は、上記の帯電ローラを有することを特徴とする。
　この発明の画像形成装置によれば、画像不良の発生を抑制することができる。 The image forming apparatus of the present invention includes the above-described charging roller.
According to the image forming apparatus of the present invention, the occurrence of image defects can be suppressed.
　本発明によれば、被帯電体への帯電を十分に均一に行うことができる帯電ローラを提供することができる。また、本発明によれば、画像不良の発生を抑制させた画像形成装置を提供することができる。 According to the present invention, it is possible to provide a charging roller capable of sufficiently uniformly charging an object to be charged. In addition, according to the present invention, it is possible to provide an image forming apparatus in which the occurrence of image defects is suppressed.
本発明の帯電ローラの一実施形態を示す、帯電ローラの軸方向に直交する方向での断面図である。FIG. 3 is a cross-sectional view in a direction orthogonal to the axial direction of the charging roller, showing an embodiment of the charging roller of the present invention. 図１に示す帯電ローラの作用効果を、帯電ローラに電圧を印加し感光体に当接させた状態で模式的に示す断面図である。FIG. 2 is a cross-sectional view schematically showing the operation effect of the charging roller shown in FIG. 1 in a state where a voltage is applied to the charging roller and brought into contact with a photosensitive member. （ａ）は、帯電ローラのシャフトの外周側に形成される各層の表面と、シャフトとの間の抵抗値の測定方法を示す図である。（ｂ）は、帯電ローラの各層の抵抗値の測定方法を示す図である。(A) is a figure which shows the measuring method of the resistance value between the surface of each layer formed in the outer peripheral side of the shaft of a charging roller, and a shaft. (B) is a figure which shows the measuring method of the resistance value of each layer of a charging roller. 本発明の画像形成装置の一実施形態を示す部分断面図である。1 is a partial cross-sectional view showing an embodiment of an image forming apparatus of the present invention.
　以下に図面を参照しつつ、本発明の帯電ローラの実施形態について例示説明する。図１は、本発明の帯電ローラの一例の構造を示す、帯電ローラの軸方向に直交する方向での断面図である。
　図示の帯電ローラ１は、複写機、プリンター等の画像形成装置で用いることが可能であって、画像形成装置内の感光体等の被帯電体に当接しまたは近接（数１０μｍの隙間）させて、当該被帯電体との間に電圧を印加することにより当該被帯電体を帯電させるものである。 Hereinafter, embodiments of the charging roller of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a structure of an example of the charging roller of the present invention in a direction orthogonal to the axial direction of the charging roller.
The illustrated charging roller 1 can be used in an image forming apparatus such as a copying machine or a printer, and is in contact with or close to a charged body such as a photoconductor in the image forming apparatus (a gap of several tens of μm). The charged body is charged by applying a voltage between the charged body and the charged body.
　ここで、帯電ローラ１は、図１に示すように、少なくとも、シャフト２と、当該シャフト２の外周面上に形成される基層３と、当該基層３よりも径方向外側に形成される中間層４とを備える。具体的には、図示の例では、シャフト２の外周面上に、径方向内側から外側に向かって、基層３、中間層４としての接着層４１、第１下層４２および第２下層４３、並びに表面層５が形成されている。なお、この帯電ローラ１では、中間層４とは、接着層４１、第１下層４２および第２下層４３などの、基層３と表面層５との間に設けられる層を指し、単に「中間層」と記載した場合には、接着層４１、第１下層４２および第２下層４３などのうちの、少なくとも一層を指すこと、或いは全部の層を指すことがあるものとする。 Here, as shown in FIG. 1, the charging roller 1 includes at least a shaft 2, a base layer 3 formed on the outer peripheral surface of the shaft 2, and an intermediate layer formed radially outside the base layer 3. 4. Specifically, in the illustrated example, on the outer peripheral surface of the shaft 2, from the radially inner side to the outer side, the base layer 3, the adhesive layer 41 as the intermediate layer 4, the first lower layer 42 and the second lower layer 43, and A surface layer 5 is formed. In the charging roller 1, the intermediate layer 4 refers to a layer provided between the base layer 3 and the surface layer 5, such as the adhesive layer 41, the first lower layer 42, and the second lower layer 43. "May indicate at least one of the adhesive layer 41, the first lower layer 42, the second lower layer 43, or all of the layers.
　シャフト２は、帯電ローラ１の軸となるものであり、良好な導電性を有するものであれば限定されないが、例えば鉄、ステンレスおよびアルミニウム等の金属製とすることができる。また、シャフト２は、十分な剛性を有していればその形状は限定されないが、中実体、またはその内部を中空にくりぬいた円筒体等にすることができる。なお、シャフト２は、剛性の観点からは、中実体が好ましい。 The shaft 2 serves as the axis of the charging roller 1 and is not limited as long as it has good conductivity. For example, the shaft 2 can be made of metal such as iron, stainless steel, and aluminum. The shape of the shaft 2 is not limited as long as it has sufficient rigidity. However, the shaft 2 can be a solid body or a cylindrical body in which the inside is hollowed. The shaft 2 is preferably a solid body from the viewpoint of rigidity.
　シャフト２の外径は、限定されるものではないが、例えば、４～１０ｍｍとすることができ、帯電ローラ１の剛性を確保しつつ、重量の増加を抑制することができる。 The outer diameter of the shaft 2 is not limited, but can be 4 to 10 mm, for example, and the increase in weight can be suppressed while ensuring the rigidity of the charging roller 1.
　基層３は、シャフト２の外周面上に形成される、導電性および弾性を有する層であり、帯電ローラ１が被帯電体に当接した際の圧力を吸収するとともにシャフト２からの電流を帯電ローラ１の外表面まで通電させる層である。
　基層３は、ゴム、樹脂またはこれらの発泡体などの材料から形成することができ、ゴムまたは樹脂としては、限定されるものではないが、例えば、ポリウレタン、シリコーンゴム、ブタジエンゴム、イソプレンゴム、クロロプレンゴム、スチレン－ブチレンゴム、エチレン－プロピレンゴム、ポリノルボルネンゴム、スチレン－ブタジエン－スチレンゴム、エピクロルヒドリンゴム等から選択される１つ以上を用いることができる。中でも、発泡させたポリウレタンが、被帯電体との密着性の観点から好ましい。 The base layer 3 is a layer having electrical conductivity and elasticity formed on the outer peripheral surface of the shaft 2, and absorbs the pressure when the charging roller 1 comes into contact with the member to be charged and charges the current from the shaft 2. This is a layer for energizing the outer surface of the roller 1.
The base layer 3 can be formed from a material such as rubber, resin, or foamed material thereof. The rubber or resin is not limited, and examples thereof include polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene. One or more selected from rubber, styrene-butylene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber and the like can be used. Among these, foamed polyurethane is preferable from the viewpoint of adhesion to an object to be charged.
　基層３には、導電性を備えるために、イオン導電剤や電子導電剤等の導電剤が添加されている。導電剤としては、限定されるものではないが、例えば、イオン導電剤としては、テトラエチルアンモニウム、テトラブチルアンモニウム、ドデシルトリメチルアンモニウム（例えば、ラウリルトリメチルアンモニウム）、ヘキサデシルトリメチルアンモニウム、オクタデシルトリメチルアンモニウム（例えば、ステアリルトリメチルアンモニウム）、ベンジルトリメチルアンモニウム、変性脂肪酸ジメチルエチルアンモニウムなどと過塩素酸、塩素酸、塩酸、臭素酸、ヨウ素酸、ホウフッ化水素酸、硫酸、エチル硫酸、カルボン酸、スルホン酸などとのアンモニウム塩；リチウム、ナトリウム、カリウム、カルシウム、マグネシウムなどのアルカリ金属やアルカリ土類金属と過塩素酸、塩素酸、塩酸、臭素酸、ヨウ素酸、ホウフッ化水素酸、トリフルオロメチル硫酸、スルホン酸などとのアルカリ金属塩またはアルカリ土類金属塩；が挙げられる。また、電子導電剤の例としては、ケッチェンブラック、アセチレンブラック等の導電性カーボン；ＳＡＦ、ＩＳＡＦ、ＨＡＦ、ＦＥＦ、ＧＰＦ、ＳＲＦ、ＦＴ、ＭＴ等のゴム用カーボン；酸化処理を施したインク用カーボン、熱分解カーボン、天然グラファイト、人造グラファイト；酸化スズ、酸化チタン、酸化亜鉛等の導電性金属酸化物；ニッケル、銅、銀、ゲルマニウム等の金属などが挙げられる。これらの導電剤は単独で用いてもよく、２種以上を混合して用いてもよい。 The base layer 3 is added with a conductive agent such as an ionic conductive agent or an electronic conductive agent in order to have conductivity. Examples of the conductive agent include, but are not limited to, for example, ionic conductive agents include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, and octadecyltrimethylammonium (for example, Stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium and the like and ammonium with perchloric acid, chloric acid, hydrochloric acid, bromic acid, iodic acid, borofluoric acid, sulfuric acid, ethyl sulfuric acid, carboxylic acid, sulfonic acid, etc. Salts; alkaline metals and alkaline earth metals such as lithium, sodium, potassium, calcium, magnesium and perchloric acid, chloric acid, hydrochloric acid, bromic acid, iodic acid, borofluoric acid, Trifluoromethyl sulfate, alkali metal salts or alkaline earth metal salts of sulfonic acid; and the like. Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; for ink subjected to oxidation treatment Examples thereof include carbon, pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium. These conductive agents may be used alone or in combination of two or more.
　基層３には、導電剤の他に任意の添加剤、例えば、フェノールやフェニルアミン等の酸化防止剤、低摩擦化剤、電荷調整剤、製泡剤、界面活性剤、充填剤などを添加することができる。 In addition to the conductive agent, an optional additive such as an antioxidant such as phenol or phenylamine, a low friction agent, a charge adjusting agent, a foaming agent, a surfactant, a filler, or the like is added to the base layer 3. be able to.
　基層３の形成は、限定されるものではないが、例えば、前述のゴムまたは樹脂に上記の導電剤および添加剤を混合し、その後、混合物を、シャフト２を配置した金型内に注入して硬化させることにより行うことができる。またゴムまたは樹脂を予め発泡させる場合には、上記の混合物を、例えば、メカニカルフロス法、水発泡法、発泡剤フロス法等の方法を用いて発泡させることができる。 The formation of the base layer 3 is not limited, but, for example, the above-mentioned rubber or resin is mixed with the above conductive agent and additive, and then the mixture is injected into a mold in which the shaft 2 is disposed. This can be done by curing. When the rubber or resin is foamed in advance, the above mixture can be foamed using a method such as a mechanical floss method, a water foam method, or a foaming agent floss method.
　接着層４１は、基層３と第１下層４２との間に位置するとともに、各層を接着させて密着性を向上させるために設けられるものである。
　接着層４１は、限定されるものではないが、ポリアミド（ナイロンなど）、ポリエステル、ウレタン変性アクリル樹脂、フェノール樹脂、アクリル樹脂、ポリウレタン、エポキシ樹脂、尿素樹脂等の材料から形成することができる。なお、基層３との接着性の観点から、ウレタン樹脂を含んで形成させることが好ましく、ウレタン樹脂とポリエステル樹脂との２種類を混合させたものを用いることがさらに好ましい。
　また、接着層４１には、基層３に添加することが可能な導電剤や添加剤を添加することができる。 The adhesive layer 41 is located between the base layer 3 and the first lower layer 42, and is provided to adhere each layer and improve adhesion.
The adhesive layer 41 is not limited, but can be formed from materials such as polyamide (such as nylon), polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, polyurethane, epoxy resin, and urea resin. In addition, from a viewpoint of adhesiveness with the base layer 3, it is preferable to form including a urethane resin, and it is more preferable to use what mixed two types of urethane resin and polyester resin.
In addition, a conductive agent or an additive that can be added to the base layer 3 can be added to the adhesive layer 41.
　接着層４１の厚さは、基層３と第１下層４２との接着性を確保するために、５～４０μｍが好ましい。 The thickness of the adhesive layer 41 is preferably 5 to 40 μm in order to ensure adhesion between the base layer 3 and the first lower layer 42.
　第１下層４２および第２下層４３は、抵抗を調整するために設けられるものである。各下層４２、４３は、限定されるものではないが、ポリアミド（ナイロンなど）、ポリエステル、ウレタン変性アクリル樹脂、フェノール樹脂、アクリル樹脂、エポキシ樹脂、ポリウレタン、尿素樹脂、フッ素樹脂等の材料から形成することができる。なお、第１下層４２および第２下層４３は、同じまたは相互に異なる材料で構成することができる。
　また、各下層４２、４３には、基層３に添加することが可能な添加剤を添加することができる。
　さらに、各下層４２、４３は、導電剤としてカーボンブラックのみを含有している。例えば導電剤としてイオン導電剤を用いた場合には、帯電ローラの使用時に、イオン導電剤が分極して当該帯電ローラの表面にイオン導電剤がブリードアウトする虞があり、汚染の原因となりうる。しかし、この実施形態では、各下層４２、４３が、導電剤としてカーボンブラックのみを含有しているので、帯電ローラ１に導電性を付与しつつ、上記のような汚染を防止することができる。 The first lower layer 42 and the second lower layer 43 are provided for adjusting the resistance. Each lower layer 42, 43 is formed of a material such as, but not limited to, polyamide (such as nylon), polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, polyurethane, urea resin, or fluororesin. be able to. The first lower layer 42 and the second lower layer 43 can be made of the same or different materials.
Further, an additive that can be added to the base layer 3 can be added to each of the lower layers 42 and 43.
Furthermore, each lower layer 42, 43 contains only carbon black as a conductive agent. For example, when an ionic conductive agent is used as the conductive agent, the ionic conductive agent may be polarized when the charging roller is used, and the ionic conductive agent may bleed out on the surface of the charging roller, which may cause contamination. However, in this embodiment, since the lower layers 42 and 43 contain only carbon black as a conductive agent, the above-mentioned contamination can be prevented while imparting conductivity to the charging roller 1.
　なお、図示の例では、下層は、１層の第１下層４２と、１層の第２下層４３との２層から構成されるが、帯電ローラ１またはその製造において目的とする性能に応じて、下層を１層、または３層以上の同じまたは相互に異なる材料からなる層で構成することもできる。 In the illustrated example, the lower layer is composed of two layers of one first lower layer 42 and one second lower layer 43, depending on the performance intended for the charging roller 1 or its manufacture. The lower layer can be composed of one layer or three or more layers made of the same or different materials.
　表面層５は、帯電ローラ１の外表面を形成するとともに、感光体などの被帯電体に電圧を印加させる際に当該被帯電体に接触する層である。表面層５は、限定されるものではないが、下層の材料と同様のものを用いて形成することができる。なお、表面層５へのトナー付着防止や表面平滑性確保等の目的に応じた材料とすることができる。
　また、表面層５には、基層３に添加することが可能な導電剤や添加剤を添加することができる。 The surface layer 5 is a layer that forms the outer surface of the charging roller 1 and is in contact with the member to be charged when a voltage is applied to the member to be charged such as a photosensitive member. The surface layer 5 is not limited, but can be formed using the same material as the lower layer. Note that a material suitable for the purpose of preventing toner adhesion to the surface layer 5 and ensuring surface smoothness can be used.
In addition, a conductive agent or additive that can be added to the base layer 3 can be added to the surface layer 5.
　なお、帯電ローラ１の表面に凹凸が存在すると、例えば凹部内にトナーがつまり画像不良の原因となり得ることから、表面層５の表面は平滑であることが好ましく、具体的には、ＪＩＳ十点平均粗さＲｚで、３０μｍ以下とすることが好ましい。 If the surface of the charging roller 1 has irregularities, for example, toner in the recesses can cause image defects. Therefore, the surface of the surface layer 5 is preferably smooth. The average roughness Rz is preferably 30 μm or less.
　上記の接着層４１、各下層４２、４３および表面層５の形成は、限定されるものではないが、各層を形成するための上記の材料を含む塗料を調整し、この塗料を例えばディッピング法やスプレー法により塗布することにより行うことができる。 The formation of the adhesive layer 41, the lower layers 42 and 43, and the surface layer 5 is not limited, but a paint containing the above materials for forming each layer is prepared, and the paint is used, for example, by dipping or It can be performed by applying by a spray method.
　ここで、上記のような構成を有する従来の帯電ローラでは、画像形成装置により得られるプリント画像にカブリと呼ばれる不良が十分に抑制できないことがあった。そして、発明者がその原因を検討したところ、従来の帯電ローラでは、帯電ローラのシャフトの外周面上に形成される基層が、軸方向で抵抗値が十分に均一にならないことがあるため、帯電ローラの表面に、軸方向で十分に均一に電圧を印加できていなかったことがわかった。
　なお、基層が、軸方向で抵抗値が十分に均一にならなくなる場合は、例えば、基層を、上述のように、ゴム、樹脂またはその発泡体を、金型内に注入して硬化させる製法で製造したときに生じることがあった。また、かかる場合、軸方向で一端側の抵抗値が、軸線方向で他端側の抵抗値よりも高くなる傾向がある。 Here, with the conventional charging roller having the above-described configuration, a defect called fog may not be sufficiently suppressed in a print image obtained by the image forming apparatus. Then, the inventors examined the cause, and in the conventional charging roller, the base layer formed on the outer peripheral surface of the shaft of the charging roller may not have a sufficiently uniform resistance value in the axial direction. It was found that the voltage could not be applied to the surface of the roller sufficiently uniformly in the axial direction.
In the case where the resistance value of the base layer does not become sufficiently uniform in the axial direction, for example, as described above, the base layer is manufactured by injecting rubber, resin, or a foam thereof into a mold and curing it. Occurs when manufactured. In such a case, the resistance value on one end side in the axial direction tends to be higher than the resistance value on the other end side in the axial direction.
　そこで、本発明の帯電ローラ１では、シャフト２に基層３が形成された積層体の、軸方向少なくとも１つの位置における当該基層３の表面と当該シャフト２との間の抵抗値Ｒ１（以下、「基層－シャフト間抵抗値Ｒ１」とも称す）、および、シャフト２に基層３から接着層４１までが形成された積層体の前記位置における、当該接着層４１の表面と当該シャフト２との間の抵抗値Ｒ２（以下、「接着層－シャフト間抵抗値Ｒ２）が、
Ｒ２＜Ｒ１
の関係を満たす。
　この構成によれば、基層３が、軸線方向で抵抗値が十分に均一になっていなくても、基層－シャフト間抵抗値Ｒ１および接着層－シャフト間抵抗値Ｒ２を上記関係にすることにより、帯電ローラ１の表面に、軸線方向で十分に均一に電圧を印加することができ、それゆえに被帯電体への帯電を十分に均一に行うことができ、帯電ローラ１を有する画像形成装置により得られる画像に不良が発生するのを抑制させることができる。 Therefore, in the charging roller 1 of the present invention, the resistance value R1 (hereinafter referred to as “the shaft 2”) between the surface of the base layer 3 and the shaft 2 in at least one position in the axial direction of the laminated body in which the base layer 3 is formed on the shaft 2. Also, the resistance between the surface of the adhesive layer 41 and the shaft 2 at the position of the laminate in which the base layer 3 to the adhesive layer 41 are formed on the shaft 2. Value R2 (hereinafter referred to as “adhesion layer-shaft resistance value R2”)
R2 <R1
Satisfy the relationship.
According to this configuration, even when the resistance value of the base layer 3 is not sufficiently uniform in the axial direction, the base layer-shaft resistance value R1 and the adhesive layer-shaft resistance value R2 are in the above relationship. A voltage can be applied to the surface of the charging roller 1 in a sufficiently uniform manner in the axial direction. Therefore, the charged body can be charged sufficiently uniformly and obtained by an image forming apparatus having the charging roller 1. It is possible to suppress the occurrence of defects in the image to be produced.
　具体的には、理論に拘束されるものではないが、帯電ローラ１を画像形成装置に用いた場合、次のように電流が帯電ローラ１内で流れるので、帯電ローラ１の表面に、軸線方向で十分に均一に電圧を印加することができると考えられる。即ち、基層－シャフト間抵抗値Ｒ１が軸方向で十分に均一になっていなく、例えば、基層３の、軸方向少なくとも１つの位置、図示の例では、基層３の中でも軸方向一端側（図２では左側）の基層－シャフト間抵抗値Ｒ１が、他端側（図２では右側）の基層－シャフト間抵抗値Ｒ１’よりも高い場合があった。そして、従来の帯電ローラでは、シャフトから表面層に向かって流れる電流に、一端側と他端側とで差が生じる（図２に模式的な断面図に示す、電流の流れとしての実線の矢印のみが存在する）。しかし、本発明の帯電ローラ１では、接着層４１内を電流が流れやすいので、基層３から接着層４１へ伝わった電流のうち、接着層４１の他端側の電流の一部が、接着層４１内を通って接着層４１の一端側へ流れることとなる（図２に示す、実線の矢印に、電気の流れとしての破線の矢印が加わる）。したがって、図示の例の帯電ローラ１では、接着層４１の外周側の層への電流が帯電ローラ１の軸方向で十分に均一になって流れることになり、帯電ローラ１の表面に、軸線方向で十分に均一に電圧を印加することができる。
　なお、図２は帯電ローラの作用効果を模式的に示した図であり、図１の帯電ローラの断面図における各寸法とは異なっている。 Specifically, without being bound by theory, when the charging roller 1 is used in an image forming apparatus, an electric current flows in the charging roller 1 as follows. It is considered that the voltage can be applied sufficiently uniformly. That is, the base layer-shaft resistance R1 is not sufficiently uniform in the axial direction. For example, at least one position of the base layer 3 in the axial direction, in the illustrated example, one end side in the axial direction of the base layer 3 (FIG. 2). In some cases, the resistance value R1 between the base layer and the shaft on the left side is higher than the resistance value R1 ′ between the base layer and the shaft on the other end side (the right side in FIG. 2). In the conventional charging roller, a difference occurs in the current flowing from the shaft toward the surface layer between the one end side and the other end side (the solid line arrow as the current flow shown in the schematic cross-sectional view of FIG. 2). Only exist). However, in the charging roller 1 of the present invention, since the current easily flows in the adhesive layer 41, a part of the current on the other end side of the adhesive layer 41 out of the current transmitted from the base layer 3 to the adhesive layer 41 is the adhesive layer. It flows into one end side of the adhesive layer 41 through the inside 41 (a broken line arrow as an electric flow is added to the solid line arrow shown in FIG. 2). Accordingly, in the illustrated charging roller 1, the current to the outer peripheral layer of the adhesive layer 41 flows sufficiently uniformly in the axial direction of the charging roller 1, and the axial direction of the charging roller 1 is increased. The voltage can be applied sufficiently uniformly.
FIG. 2 is a diagram schematically showing the operation and effect of the charging roller, which is different from each dimension in the cross-sectional view of the charging roller in FIG.
　なお、「基層－シャフト間抵抗値」は、図３（ａ）に示すように、シャフト２の外周面上に基層３が形成された積層体について、積層体の軸方向で少なくとも１つの位置における基層３の表面に抵抗測定器Ｄの一方の電極Ｅを取り付け、また、他方の電極Ｅをシャフト２に取り付けて測定した抵抗値を指す。また、「接着層－シャフト間抵抗値」は、同様に、シャフト２の外周面上に基層３から接着層４１までが形成された積層体について、積層体の軸方向で少なくとも１つの位置における、接着層４１の表面とシャフト２との間で測定した抵抗値を指す。 As shown in FIG. 3A, the “base layer-shaft resistance value” is the value of at least one position in the axial direction of the laminated body in which the base layer 3 is formed on the outer peripheral surface of the shaft 2. The resistance value measured by attaching one electrode E of the resistance measuring device D to the surface of the base layer 3 and attaching the other electrode E to the shaft 2 is indicated. Similarly, the “resistance value between the adhesive layer and the shaft” is the same for the laminated body in which the base layer 3 to the adhesive layer 41 are formed on the outer peripheral surface of the shaft 2 at at least one position in the axial direction of the laminated body. The resistance value measured between the surface of the adhesive layer 41 and the shaft 2 is indicated.
　また、接着層４１の抵抗値Ｒｍは、４ＭΩ以下であることが好ましい。この構成によれば、さらに効果的に画像不良の発生を抑制することができる。なお、同様の観点からは、当該抵抗値Ｒｍは、１．０ＭΩ以下であることがより好ましい。 The resistance value Rm of the adhesive layer 41 is preferably 4 MΩ or less. According to this configuration, it is possible to more effectively suppress the occurrence of image defects. From the same viewpoint, the resistance value Rm is more preferably 1.0 MΩ or less.
　なお、各層の「抵抗値」は、図３（ｂ）に示すように、測定する層の内径と同じ程度の外径を有する樹脂製の円柱状棒Ａに、当該測定する層を形成させ、抵抗測定器Ｄの２つの電極Ｅを５ｍｍで離間させた状態で測定するものとする。 In addition, as shown in FIG. 3B, the “resistance value” of each layer is such that the layer to be measured is formed on a cylindrical rod A made of resin having the same outer diameter as the inner diameter of the layer to be measured. It is assumed that measurement is performed in a state where the two electrodes E of the resistance measuring device D are separated by 5 mm.
　また、基層３の抵抗値は、０．００１～０．１ＭΩであることが好ましい。十分に被帯電体を帯電させることができる。 The resistance value of the base layer 3 is preferably 0.001 to 0.1 MΩ. The object to be charged can be sufficiently charged.
　さらに、本実施形態の帯電ローラ１では、基層－シャフト間抵抗値Ｒ１が、接着層－シャフト間抵抗値Ｒ２よりも大きくなるとともに、さらに、接着層４１の軸方向で接着層－シャフト間抵抗値が最も大きくなる位置での接着層－シャフト間抵抗値Ｒ２、および、接着層４１の接着層－シャフト間抵抗値が軸方向で最も小さくなる位置での接着層－シャフト間抵抗値Ｒ２’の差が、０．０３５ＭΩ以下であることが好ましい。接着層－シャフト間抵抗値Ｒ２およびＲ２’の差を０．０３５ＭΩ以下にすることにより、基層３が、軸線方向で抵抗値が十分に均一になっていなくても、帯電ローラ１の表面に、軸線方向で十分に均一に電圧を印加することができ、それゆえに画像不良の発生を抑制させることができる。 Further, in the charging roller 1 of the present embodiment, the base layer-shaft resistance value R1 is larger than the adhesive layer-shaft resistance value R2, and further, the adhesive layer-shaft resistance value in the axial direction of the adhesive layer 41. The difference between the adhesive layer-shaft resistance value R2 at the position where the resistance is the largest, and the adhesive layer-shaft resistance value R2 'at the position where the adhesive layer-shaft resistance value of the adhesive layer 41 is the smallest in the axial direction. Is preferably 0.035 MΩ or less. By setting the difference between the adhesive layer-shaft resistance values R2 and R2 ′ to 0.035 MΩ or less, even if the base layer 3 does not have a sufficiently uniform resistance value in the axial direction, The voltage can be applied sufficiently uniformly in the axial direction, and therefore the occurrence of image defects can be suppressed.
　ところで、基層３および接着層４１が上述のような基層－シャフト間抵抗値および接着層－シャフト間抵抗値を有するために、基層３および接着層４１が次のように導電剤を含有することが好ましい。
　基層３は、導電剤として、高温高湿環境下において画像不良を抑制することができるので、イオン導電剤を含むことが好ましい。また、導電剤の配合量は、基層１００重量部に対して０．０５～１重量部の割合が好ましく、より好ましくは、基層１００重量部に対して０．１～０．２重量部の割合である。 Incidentally, since the base layer 3 and the adhesive layer 41 have the base layer-shaft resistance value and the adhesive layer-shaft resistance value as described above, the base layer 3 and the adhesive layer 41 may contain a conductive agent as follows. preferable.
Since the base layer 3 can suppress image defects as a conductive agent in a high temperature and high humidity environment, the base layer 3 preferably contains an ionic conductive agent. The blending amount of the conductive agent is preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the base layer, and more preferably 0.1 to 0.2 part by weight with respect to 100 parts by weight of the base layer. It is.
　接着層４１は、導電剤として、ブリードアウトを抑制する観点から、カーボンブラックのみを含むことが好ましい。また、導電剤の配合量は、当該接着層４１の樹脂成分１００重量部に対して４５～５５重量部の割合が好ましく、より好ましくは、接着層４１の樹脂成分１００重量部に対して５０重量部の割合である。特に、抵抗Ｒｍが４ＭΩ以下とするためには、接着層４１の樹脂成分１００重量部に４５重量部以上の導電剤を配合することが好ましい。 The adhesive layer 41 preferably contains only carbon black as a conductive agent from the viewpoint of suppressing bleeding out. The blending amount of the conductive agent is preferably 45 to 55 parts by weight with respect to 100 parts by weight of the resin component of the adhesive layer 41, and more preferably 50 parts by weight with respect to 100 parts by weight of the resin component of the adhesive layer 41. The ratio of parts. In particular, in order to set the resistance Rm to 4 MΩ or less, it is preferable to add 45 parts by weight or more of a conductive agent to 100 parts by weight of the resin component of the adhesive layer 41.
　ここで、本発明の画像形成装置の一実施形態について、以下に図面を参照しつつ、例示説明する。
　本発明の画像形成装置は、上述した帯電ローラを有することを特徴とする。本発明の画像形成装置は、上記帯電ローラを有する以外、特に制限はなく、公知の構成とすることができる。 Here, an image forming apparatus according to an embodiment of the invention will be described with reference to the drawings.
The image forming apparatus of the present invention includes the above-described charging roller. The image forming apparatus of the present invention is not particularly limited except that it includes the above-described charging roller, and can have a known configuration.
　図４は、本発明の画像形成装置６の一実施形態を示す部分断面図である。図示例の画像形成装置６は、静電潜像を保持した感光体７と、感光体７の近傍（図では上方）に位置し感光体７を帯電させるための帯電ローラ１と、トナーを供給するためのトナー供給ローラ８と、トナー供給ローラ８と感光体７との間に配置された現像ローラ９と、現像ローラ９の近傍（図では上方）に設けられた成層ブレード１０と、感光体７の近傍（図では下方）に位置する転写ローラ１１と、感光体７に隣接して配置されたクリーニングローラ１２とを備える。なお、本発明の画像形成装置６は、更に画層形成装置に通常用いられる公知の部品（図示せず）を備えることができる。 FIG. 4 is a partial sectional view showing an embodiment of the image forming apparatus 6 of the present invention. The image forming apparatus 6 in the illustrated example supplies a photosensitive member 7 holding an electrostatic latent image, a charging roller 1 located near the photosensitive member 7 (upward in the drawing) for charging the photosensitive member 7, and toner. A toner supply roller 8, a developing roller 9 disposed between the toner supply roller 8 and the photosensitive member 7, a stratifying blade 10 provided in the vicinity of the developing roller 9 (upward in the drawing), and a photosensitive member 7 is provided with a transfer roller 11 located in the vicinity (lower in the drawing) 7 and a cleaning roller 12 disposed adjacent to the photoconductor 7. In addition, the image forming apparatus 6 of the present invention can further include a known component (not shown) that is normally used in the image layer forming apparatus.
　図示例の画像形成装置６においては、感光体７に帯電ローラ１を当接させて、感光体７と帯電ローラ１との間に電圧を印加して、感光体７を一定電位に帯電させた後、露光機（図示せず）により静電潜像を感光体７上に形成する。次に、感光体７と、トナー供給ローラ８と、現像ローラ９とが、図中の矢印方向に回転することで、トナー供給ローラ８上のトナーが現像ローラ９を経て感光体７に送られる。現像ローラ９上のトナーは、成層ブレード１０により、均一な薄層に整えられ、現像ローラ９と感光体７とが接触しながら回転することにより、トナーが現像ローラ９から感光体７の静電潜像に付着し、該潜像が可視化する。潜像に付着したトナーは、転写ローラ１１で紙等の記録媒体に転写され、また、転写後に感光体７上に残留するトナーは、クリーニングローラ１２によって除去される。ここで、本発明の画像形成装置６においては、上述した本発明の帯電ローラ１を用いることで、画像を、画像不良の発生を抑制しつつ形成することが可能となる。 In the illustrated image forming apparatus 6, the charging roller 1 is brought into contact with the photoreceptor 7, and a voltage is applied between the photoreceptor 7 and the charging roller 1 to charge the photoreceptor 7 to a constant potential. Thereafter, an electrostatic latent image is formed on the photoconductor 7 by an exposure machine (not shown). Next, the photoreceptor 7, the toner supply roller 8, and the developing roller 9 rotate in the direction of the arrow in the drawing, so that the toner on the toner supply roller 8 is sent to the photoreceptor 7 through the developing roller 9. . The toner on the developing roller 9 is adjusted to a uniform thin layer by the stratifying blade 10 and rotates while the developing roller 9 and the photoconductor 7 are in contact with each other. Attaches to the latent image, and the latent image becomes visible. The toner adhering to the latent image is transferred to a recording medium such as paper by the transfer roller 11, and the toner remaining on the photoreceptor 7 after the transfer is removed by the cleaning roller 12. Here, in the image forming apparatus 6 of the present invention, by using the above-described charging roller 1 of the present invention, an image can be formed while suppressing the occurrence of image defects.
　以上、図面を参照して本発明の実施形態を説明したが、本発明の帯電ローラおよび画像形成装置は、上記一例に限定されることは無く、適宜変更を加えることができる。 As described above, the embodiments of the present invention have been described with reference to the drawings. However, the charging roller and the image forming apparatus of the present invention are not limited to the above example, and can be appropriately modified.
　以下、実施例により本発明を更に詳細に説明するが、本発明は下記の実施例になんら限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.
　基層－シャフト間抵抗値が、帯電ローラの基層の軸方向で他端側よりも一端側で大きくなっている下記の構成を有する各帯電ローラについて、それらを画像形成装置に用いてプリントした画像に不良（カブリ）が生じるか否かを検討した。
　実施例１の帯電ローラは、図１に示すように、シャフト（快削鋼製）、基層（材料：ポリウレタン、導電剤：イオン導電剤（製造会社名：日本カーリット社、商品名：ＰＥＬ－４６（有機ホウ素錯体リチウム塩）及びアセチレンブラック、アセチレンブラックの含有量：基材樹脂成分１００重量部に対して１．６重量部）、接着層（材料：水系ポリウレタンおよび水系ポリエステル樹脂の混合物、導電剤：アセチレンブラック）、第１下層（材料：アクリル系樹脂、導電剤：アセチレンブラック、導電剤含有量：第１下層樹脂成分１００重量部に対して２８重量部）、第２下層（材料：水系ウレタン樹脂と水系ポリエステル樹脂の混合物、導電剤：アセチレンブラック、導電剤含有量：第２下層樹脂成分１００重量部に対して１８重量部）および表面層（材料：フッ素系樹脂、導電剤：アセチレンブラック、導電剤含有量：表面層樹脂成分１００重量部に対して２０重量部）を有している。また、基層および接着層に含まれる、各層１００重量部に対する導電剤の量と、当該導電剤を含んだ基層および接着層の軸方向一端側および他端側の表面とシャフトの間での基層－シャフト間抵抗値Ｒ１、Ｒ１’および接着層－シャフト間抵抗値Ｒ２、Ｒ２’とを表１に示す。なお、各層に導電剤として含有させたアセチレンブラックは、ＤＢＰ吸油量が４５ｃｍ3／１００ｇであり、一次粒形２４μｍ、二次粒形１０９μｍである。
　実施例２～４、並びに比較例１および２の帯電ローラは、表１に示す諸元を変化させた以外、実施例１の帯電ローラと同じ構成を有する。 For each charging roller having the following configuration in which the resistance value between the base layer and the shaft is larger on the one end side than on the other end side in the axial direction of the base layer of the charging roller, the image is printed on the image using the image forming apparatus. It was examined whether defects (fogging) would occur.
As shown in FIG. 1, the charging roller of Example 1 includes a shaft (made of free-cutting steel), a base layer (material: polyurethane, conductive agent: ionic conductive agent (manufacturer name: Nippon Carlit Co., Ltd., trade name: PEL-46). (Organic boron complex lithium salt) and acetylene black, acetylene black content: 1.6 parts by weight with respect to 100 parts by weight of the base resin component, adhesive layer (material: mixture of water-based polyurethane and water-based polyester resin, conductive agent : Acetylene black), first lower layer (material: acrylic resin, conductive agent: acetylene black, conductive agent content: 28 parts by weight with respect to 100 parts by weight of first lower layer resin component), second lower layer (material: aqueous urethane) A mixture of resin and water-based polyester resin, conductive agent: acetylene black, conductive agent content: 18 parts by weight with respect to 100 parts by weight of the second lower layer resin component) And a surface layer (material: fluororesin, conductive agent: acetylene black, conductive agent content: 20 parts by weight with respect to 100 parts by weight of the surface layer resin component) and included in the base layer and the adhesive layer The amount of the conductive agent with respect to 100 parts by weight of each layer, and the base layer-shaft resistance values R1, R1 ′ between the shaft and the surface on one end side and the other end side in the axial direction of the base layer and the adhesive layer containing the conductive agent, and adhesive layer -. showing the shaft resistance value R2, R2 'in Table 1 it should be noted that acetylene black which contains as the conductive agent in each layer, a DBP oil absorption of 45cm 3/100 g, a primary particle shape 24 [mu] m, secondary The particle shape is 109 μm.
The charging rollers of Examples 2 to 4 and Comparative Examples 1 and 2 have the same configuration as the charging roller of Example 1 except that the specifications shown in Table 1 are changed.
　表中のシャフト間抵抗値の測定は、図３（ａ）に示すように、測定する層の軸方向一端または他端から軸方向内側に１２．５ｍｍ離隔した位置に、抵抗測定器Ｄの幅５ｍｍの電極Ｅの幅方向中心が位置するように、当該層の周囲に巻きつけて配置し、そしてシャフトとの間に２００Ｖの電圧を印加した際の抵抗値を抵抗測定器Ｄで測定した。
　上記の各実施例１～４並びに比較例１および２の帯電ローラを用いた画像形成装置を、高温多湿（３０℃、８５％）環境下に１日放置後、高温多湿環境下で、当該装置を用いて、２万枚プリントした後の画像に不良（カブリ）が生じるか否かについて官能評価した結果を表１に示す。
As shown in FIG. 3A, the resistance value between the shafts in the table is measured by measuring the width of the resistance measuring instrument D at a position spaced 12.5 mm inward in the axial direction from one end or the other end of the layer to be measured. The resistance value when the voltage of 200 V was applied between the shaft and the shaft was measured with a resistance measuring device D so that the center of the electrode E in the width direction of 5 mm was positioned.
The image forming apparatus using the charging roller of each of Examples 1 to 4 and Comparative Examples 1 and 2 is left in a high temperature and high humidity (30 ° C., 85%) environment for one day, and then the high temperature and high humidity environment. Table 1 shows the result of sensory evaluation on whether or not a defect (fogging) occurs in an image after printing 20,000 sheets.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001

　表１の結果より、実施例１～４の帯電ローラは、Ｒ１がＲ２よりも大きいので、比較例の帯電ローラよりも、各帯電ローラを有する画像形成装置でプリントした画像に生じる不良を抑制することができたことがわかる。したがって、実施例１～４では、帯電ローラ１の表面に、軸線方向で十分に均一に電圧が印加されて、被帯電体への帯電を十分に均一に行うことができた。 From the results shown in Table 1, since the charging rollers of Examples 1 to 4 have R1 larger than R2, the defects generated in the image printed by the image forming apparatus having each charging roller are suppressed more than the charging roller of the comparative example. I understand that I was able to. Therefore, in Examples 1 to 4, the surface of the charging roller 1 was sufficiently uniformly applied with a voltage in the axial direction, and the object to be charged was sufficiently uniformly charged.
　続いて、帯電ローラの接着層に導電剤を表２に示す配合量で含有させた場合の、接着層の抵抗値を調査した。抵抗値の測定は、図３（ｂ）に示すように、接着層と同じ程度の外径を有する樹脂製の円柱状棒Ａに、接着層を形成させ、幅５ｍｍの電極Ｅの２つを５ｍｍで離間させた状態で抵抗測定器Ｄを用いて測定した。
　なお、接着層の膜厚は９μｍである。 Subsequently, the resistance value of the adhesive layer when the conductive agent was contained in the adhesive layer of the charging roller in the blending amount shown in Table 2 was investigated. As shown in FIG. 3B, the resistance value is measured by forming an adhesive layer on a resin cylindrical rod A having the same outer diameter as that of the adhesive layer, and connecting two electrodes E having a width of 5 mm. It measured using resistance measuring device D in the state spaced apart by 5 mm.
The film thickness of the adhesive layer is 9 μm.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１および表２より、比較例１および２、並びに実施例１～４において、帯電ローラの表面に、軸線方向で十分に均一に電圧を印加することを可能とする、帯電ローラの接着層に添加する導電剤量が、４５重量部以上であり、かかる量の導電剤を接着層に添加すると抵抗値を４ＭΩ以下になることがわかる。 From Tables 1 and 2, in Comparative Examples 1 and 2 and Examples 1 to 4, the surface of the charging roller can be applied with a sufficiently uniform voltage in the axial direction on the surface of the charging roller. It can be seen that the amount of the conductive agent to be added is 45 parts by weight or more, and that the resistance value becomes 4 MΩ or less when such an amount of the conductive agent is added to the adhesive layer.
　本発明によれば、被帯電体への帯電を十分に均一に行うことができる帯電ローラを提供することができる。また、本発明によれば、画像不良の発生を抑制させた画像形成装置を提供することができる。 According to the present invention, it is possible to provide a charging roller capable of sufficiently uniformly charging an object to be charged. In addition, according to the present invention, it is possible to provide an image forming apparatus in which the occurrence of image defects is suppressed.
１：帯電ローラ
２：シャフト
３：基層
４：中間層
４１：接着層（中間層）
４２：第１下層（中間層）
４３：第２下層（中間層）
５：表面層
６：画像形成装置
７：感光体
８：トナー供給ローラ
９：現像ローラ
１０：成層ブレード
１１：転写ローラ
１２：クリーニングローラ
Ａ：樹脂製の円柱状棒
Ｄ：抵抗測定器
Ｅ：電極 1: Charging roller 2: Shaft 3: Base layer 4: Intermediate layer 41: Adhesive layer (intermediate layer)
42: 1st lower layer (intermediate layer)
43: Second lower layer (intermediate layer)
5: Surface layer 6: Image forming apparatus 7: Photoconductor 8: Toner supply roller 9: Developing roller 10: Layering blade 11: Transfer roller 12: Cleaning roller A: Resin cylindrical rod D: Resistance measuring device E: Electrode

Claims (4)

  1. 　被帯電体との間に電圧を印加することにより当該被帯電体を帯電させる帯電ローラであって、
    　シャフトと、当該シャフトの外周面上に形成された基層と、当該基層よりも径方向外側に形成された中間層と、当該中間層の径方向外側に形成され、前記帯電ローラの外表面を形成する表面層とを順次備え、
    　前記中間層が、導電剤としてカーボンブラックのみを含有する下層と、当該下層および前記基層の間に位置して当該下層および当該基層を接着させる接着層とからなり、
    　前記シャフトに前記基層が形成された積層体の、軸方向で少なくとも１つの位置における当該基層の表面と当該シャフトとの間の抵抗値Ｒ１、および、
    　前記シャフトに前記基層から前記接着層までが形成された積層体の前記位置における、当該接着層の表面と当該シャフトとの間の抵抗値Ｒ２が、
    Ｒ２＜Ｒ１
    の関係を満たすことを特徴とする、帯電ローラ。     A charging roller for charging the object to be charged by applying a voltage to the object to be charged,
    A shaft, a base layer formed on the outer peripheral surface of the shaft, an intermediate layer formed radially outward from the base layer, and formed on the radial outer side of the intermediate layer to form the outer surface of the charging roller And a surface layer to sequentially
    The intermediate layer comprises a lower layer containing only carbon black as a conductive agent, and an adhesive layer that is located between the lower layer and the base layer and adheres the lower layer and the base layer,
    A resistance value R1 between the surface of the base layer and the shaft at at least one position in the axial direction of the laminate in which the base layer is formed on the shaft, and
    The resistance value R2 between the surface of the adhesive layer and the shaft at the position of the laminate in which the base layer to the adhesive layer are formed on the shaft,
    R2 <R1
    A charging roller characterized by satisfying the relationship:
  2. 　前記抵抗値Ｒ１およびＲ２が、
    １．０５≦Ｒ１／Ｒ２
    の関係を満たす、請求項１に記載の帯電ローラ。     The resistance values R1 and R2 are
    1.05 ≦ R1 / R2
    The charging roller according to claim 1, wherein the relationship is satisfied.
  3. 　前記接着層の抵抗値Ｒｍが、４ＭΩ以下である、請求項１または２に記載の帯電ローラ。 The charging roller according to claim 1 or 2, wherein a resistance value Rm of the adhesive layer is 4 MΩ or less.
  4. 　請求項１～３のいずれかに記載の帯電ローラを有することを特徴とする、画像形成装置。 An image forming apparatus comprising the charging roller according to any one of claims 1 to 3.
PCT/JP2015/003204 2014-07-01 2015-06-25 Charging roller, and image formation device WO2016002172A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002229305A (en) * 2001-02-05 2002-08-14 Bridgestone Corp Electrifying roller and electrifying device using the same
JP2003162130A (en) * 2001-11-28 2003-06-06 Fuji Xerox Co Ltd Image forming apparatus
JP2004245933A (en) * 2003-02-12 2004-09-02 Bridgestone Corp Electrifying roller and electrifying device using the same
JP2011039348A (en) * 2009-08-13 2011-02-24 Bridgestone Corp Conductive roller and method for manufacturing the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002229305A (en) * 2001-02-05 2002-08-14 Bridgestone Corp Electrifying roller and electrifying device using the same
JP2003162130A (en) * 2001-11-28 2003-06-06 Fuji Xerox Co Ltd Image forming apparatus
JP2004245933A (en) * 2003-02-12 2004-09-02 Bridgestone Corp Electrifying roller and electrifying device using the same
JP2011039348A (en) * 2009-08-13 2011-02-24 Bridgestone Corp Conductive roller and method for manufacturing the same

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