JP2005221776A - Conductive roller and process cartridge having the same, and image forming apparatus having the process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller which can stably maintain a gap between a latent image carrier and the conductive roller even long-term, which can uniformly electrify the surface of the image carrier, and which can improve the durability, even if it is used over a long period. <P>SOLUTION: In the conductive roller having a conductive support 1, an electrical resistance adjustment layer 2 formed on the conductive support 1, and a gap-maintaining member 3 provided on both ends of the electrical resistance adjustment layer 2, the gap maintaining member 3 includes at least one recessed groove 4 which is oblique in direction with respect to the axial line of the conductive roller 10, on the outer circumferential surface thereof. The recessed groove 4 is provided in the direction toward the end part of the conductive roller 10 by the rotation of the conductive roller 10. Preferably, the recessed groove 4 is disposed at an angle θ, with respect to the axial line of the conductive roller 10 so that there is no section such that only the recessed groove 4 exist in the axial direction of the conductive roller 10, at all the positions in the entire circumference of the gap-maintaining member 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a conductive roller used in an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile, a process cartridge having the conductive roller, and an image forming apparatus having the process cartridge.

  In an electrophotographic image forming apparatus such as a conventional electrophotographic copying machine, laser printer, or facsimile, a charging roller that performs charging processing on an image carrier (photosensitive member) and toner on the photosensitive member A conductive roller is used as a transfer roller for performing the transfer process. FIG. 4 is an explanatory view of an electrophotographic image forming apparatus having a conventional charging roller.

  In FIG. 4, reference numeral 120 denotes a conventional electrophotographic image forming apparatus. A conventional electrophotographic image forming apparatus 120 includes a photosensitive drum 101 on which an electrostatic latent image is formed, a charging roller 102 that performs charging processing in contact with the photosensitive drum 101, an exposure unit 103 such as a laser beam, and a photosensitive member. A developing roller 104 for attaching toner to the electrostatic latent image on the photosensitive drum 101, a power pack 105 for applying a DC voltage to the charging roller 102, and a transfer roller for transferring the toner image on the photosensitive drum 101 to the recording paper 107. 106, a cleaning device 108 for cleaning the photosensitive drum 101 after the transfer process, and a surface potential meter 109 for measuring the surface potential of the photosensitive drum 101.

  The conventional electrophotographic image forming apparatus 120 is a process cartridge detachable apparatus. That is, in the conventional electrophotographic image forming apparatus 120, the process equipment including the photosensitive drum 101, the charging roller 102, the developing roller 104, and the cleaning device 108 can be detachably attached to the image forming apparatus main body. The process cartridge 110 is used. The process cartridge 110 only needs to include at least the photosensitive drum 101 and the charging roller 102. The process cartridge 110 is connected to a drive system and an electrical system on the image forming apparatus main body side by being mounted at a predetermined position on the image forming apparatus. In FIG. 4, functional units normally required in other electrophotographic processes are omitted because they are not required in this specification.

  Next, a basic image forming operation of the conventional electrophotographic image forming apparatus 120 will be described.

  When a DC voltage is supplied from the power pack 105 to the charging roller 102 in contact with the photosensitive drum 101, the surface of the photosensitive drum 101 is uniformly charged at a high potential. Immediately thereafter, when image light is irradiated onto the surface of the photosensitive drum 101 by the exposure unit 103, the potential of the irradiated portion of the photosensitive drum 101 is lowered. It is known that such a charging mechanism to the surface of the photosensitive drum 101 by the charging roller 102 is a discharge according to Paschen's law in a minute space between the charging roller 102 and the photosensitive drum 101.

  Since the image light has a light amount distribution according to white / black of the image, when the image light is irradiated, the potential distribution corresponding to the recorded image on the surface of the photosensitive drum 101 by the irradiation of the image light, that is, An electrostatic latent image is formed. When the portion of the photosensitive drum 101 on which the electrostatic latent image is formed in this way passes through the developing roller 104, toner adheres according to the level of the potential, and a toner image that visualizes the electrostatic image is formed. Is done. The recording paper 107 is conveyed by a registration roller (not shown) at a predetermined timing to the portion of the photosensitive drum 101 where the toner image is formed, and overlaps the toner image. Then, after the toner image is transferred onto the recording paper by the transfer roller 106, the recording paper 107 is separated from the photosensitive drum 101. The separated recording paper 107 is conveyed through a conveyance path, heated and fixed by a fixing unit (not shown), and then discharged outside the apparatus. When the transfer is completed in this manner, the surface of the photosensitive drum 101 is cleaned by the cleaning device 108, and the residual charge is removed by a quenching lamp (not shown), so that the next image forming process is performed. Prepared for.

As a conventional charging method using a charging roller, there is a contact charging method in which a charging roller is brought into contact with a photosensitive drum (see Patent Documents 1 and 2). ,
(1) The substance constituting the charging roller oozes out from the charging roller, and this adheres to the surface of the object to be charged and leaves a charge roller mark.
(2) When an AC voltage is applied to the charging roller, the charging roller that is in contact with the member to be charged vibrates, so that a charging noise is generated.
(3) Since the toner on the photosensitive drum adheres to the charging roller (particularly, the above-described oozing causes toner adhesion to occur more easily), so that the charging performance of the charging roller is reduced.
(4) the substance constituting the charging roller adheres to the photosensitive drum, and
(5) The charging roller is permanently deformed when the photosensitive drum is stopped for a long time.
There was a problem.

  As a technique for solving such a problem, a charging device using a proximity charging method (see Patent Documents 3 and 4) in which a charging roller is brought close to a photosensitive drum has been proposed. In the charging device using this proximity charging method, the photosensitive drum is charged by applying a voltage to the charging roller with the charging roller facing the photosensitive drum at a closest distance (50 to 300 μm). It is a thing. In the charging device using the proximity charging method, the roller and the photosensitive drum are not in contact with each other. Therefore, the substance constituting the charging roller, which has been a problem in the conventional charging device using the contact charging method, is transferred to the photosensitive drum. There is no problem of adhesion and permanent deformation when the photosensitive drum is stopped for a long time. Further, in this charging device using the proximity charging method, the toner adhering to the charging roller is reduced, so that the toner on the photosensitive drum is less likely to adhere to the charging roller. Therefore, it can be said that the charging device using the proximity charging method is an excellent charging device.

  In the charging device using the proximity charging method described in Patent Documents 3 and 4, spacer ring layers are provided at both ends of the charging roller in order to maintain a gap between the charging roller and the photosensitive drum. However, since these charging devices using the proximity charging method have not been devised to precisely set the gap, the gap varies due to variations in the dimensional accuracy of the charging roller and the spacer ring. There was a problem that the potential fluctuated without being uniform.

In order to solve such a problem, a charging device (see Patent Document 5) provided with a tape-shaped gap holding means having a predetermined thickness has been proposed. In the apparatus, if this is used for a long period of time, the tape-like gap holding means is worn, and toner enters and adheres between the charging roller and the tape-like gap holding means. There was a problem that a gap could not be maintained between the surface of the charging roller. In addition, the charging device provided with the tape-shaped gap holding means has a problem in that the thickness of the tape-like gap holding means varies, so that a highly accurate gap cannot be formed.
JP-A 63-149668 JP-A-1-267667 Japanese Patent Laid-Open No. 3-240076 JP-A-4-358175 JP-A-5-107871

  The present invention aims to solve this problem.

  That is, the present invention can maintain a stable gap between the latent image carrier and the conductive roller even when used for a long period of time, and can uniformly charge the surface of the image carrier and is durable. It is an object of the present invention to provide a conductive roller capable of improving performance, a process cartridge having the conductive roller, and an image forming apparatus having the process cartridge.

  In order to achieve the above-described object, the invention described in claim 1 is provided with a conductive support, an electric resistance adjusting layer formed on the conductive support, and both ends of the electric resistance adjusting layer. A conductive roller having a gap holding member, and the gap holding member has one or more grooves on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller. The conductive roller is characterized in that the groove is provided in a direction toward the end of the conductive roller by the rotation of the conductive roller.

  According to a second aspect of the present invention, in the first aspect of the present invention, the gap holding member has a plurality of concave grooves on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller. It is characterized by that.

  The invention described in claim 3 is the invention described in claim 1 or 2, wherein the groove is only the groove in the axial direction of the conductive roller at all positions around the gap holding member. It is characterized by being arranged at an angle θ with respect to the axis of the conductive roller so that there is no portion where is present.

  The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the groove width of the groove is larger than the average particle diameter of the toner.

  The invention described in claim 5 is characterized in that, in the invention described in any one of claims 1 to 4, the conductive roller is a charging roller.

  According to a sixth aspect of the present invention, there is provided a process cartridge characterized in that the charging roller according to the fifth aspect is provided so as to be disposed close to a member to be charged.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising the process cartridge according to the sixth aspect.

  (1) According to the invention described in claim 1, the conductive support, the electrical resistance adjustment layer formed on the conductive support, and the void holding provided at both ends of the electrical resistance adjustment layer In the conductive roller having a member, the gap holding member has one or more concave grooves on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller, and the concave grooves are Since the conductive roller is provided in a direction toward the end of the conductive roller by rotation of the conductive roller, toner particles and the like on the gap holding member are passed through the concave groove by rotation of the conductive roller. The toner can be conveyed to the end of the roller, so that toner particles can be prevented from entering and sticking, and therefore, even when used for a long time, between the latent image carrier and the conductive roller. Maintaining a stable air gap, the surface of the image carrier It is possible to charge to one, it is possible to improve the durability.

  (2) According to the invention described in claim 2, since the gap holding member has a large number of concave grooves on the outer peripheral surface thereof which are inclined with respect to the axis of the conductive roller. Due to the rotation of the conductive roller, the frequency of conveying particles such as toner particles on the gap holding member through the concave groove to the end of the conductive roller increases.

  (3) According to the invention described in claim 3, the concave groove does not have a portion where only the concave groove exists in the axial direction of the conductive roller at all the positions of the gap holding member. Since the conductive roller is disposed at an angle θ with respect to the axis of the conductive roller, it is possible to prevent the occurrence of micro-vibration that occurs when the photosensitive member falls into the concave groove, thereby obtaining stable image quality. Can do.

  (4) According to the invention described in claim 4, since the groove width of the groove is larger than the average particle diameter of the toner, it is prevented that particles such as toner particles remain in the groove and clogging occurs. For this reason, particles such as toner particles can be satisfactorily conveyed to the end of the conductive roller over a long period of time.

  (5) According to the invention described in claim 5, since the conductive roller is a charging roller, the surface of the photosensitive member can be charged in a non-contact manner. By forming the charging roller with a hard material, high accuracy can be achieved, and thus uneven charging can be prevented.

  (6) According to the invention described in claim 6, since the charging roller according to claim 5 is a process cartridge provided so as to be disposed close to the member to be charged, the process roller is stable over a long period of time. The image quality can be obtained, and the replacement can be simplified by user maintenance.

  (7) According to the invention described in claim 7, since the image forming apparatus having the process cartridge described in claim 6 is used, an image with high reliability and high image quality can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of a conductive roller showing an embodiment of the present invention. FIG. 2 is a schematic diagram showing a state where the conductive roller is disposed on the photosensitive drum. FIG. 3 is a partially enlarged explanatory view of the conductive roller shown in FIG.

  In FIG. 1, 10 is a conductive roller. The conductive roller 10 includes a conductive support 1, an electric resistance adjustment layer 2 formed on the conductive support 1, and gap holding members 3 and 3 provided at both ends of the electric resistance adjustment layer 2. ,have. The gap holding members 3 and 3 have one or more concave grooves 4 on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller 10, and the concave grooves 4 It is provided in a direction toward the end of the conductive roller by the rotation of the conductive roller.

  As described above, the gap holding members 3, 3 have one or more concave grooves 4 on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller 10. Since the rotation of the conductive roller 10 is provided in a direction toward the end of the conductive roller 10, the toner particles on the gap holding members 3, 3 are passed through the concave groove 4 by the rotation of the conductive roller 10. The particles can be transported to the end of the conductive roller 10, so that the particles such as toner particles can be prevented from entering and fixing. The surface of the image carrier can be uniformly charged while maintaining a stable gap between the conductive roller 10 and the conductive roller 10, and the durability can be improved.

  In the present invention, the gap holding members 3, 3 preferably have a large number of concave grooves 4 on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller 10. As described above, when the gap holding members 3, 3 have a large number of concave grooves 4 on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller 10, The frequency of transporting particles such as toner particles on the gap holding members 3 and 3 to the end of the conductive roller 10 through the concave groove 4 by rotation increases.

As shown in FIG. 2, the conductive roller 10 according to the present invention is disposed in contact with the photosensitive drum 5 with an arbitrary pressure. The gap holding members 3 and 3 are formed in a non-image forming area excluding the image forming area. When the conductive roller 10 is used as a charging roller in this state, the photosensitive drum 5 can be charged by applying a voltage to the conductive roller 10. When the conductive roller 10 is used as a developing roller and a transfer roller, it can be performed in the same manner. In that case,
It is preferable that the resistance adjusting layer width <the photosensitive layer width.

  The gap G between the conductive roller 10 and the photosensitive drum 5 needs to be kept at a predetermined value, and is preferably 100 μm or less. When the gap G is increased, electrical deterioration or abnormal discharge of the photosensitive drum 5 is likely to occur, and therefore it is necessary to increase the voltage application condition to the conductive roller 10. The gap holding members 3 and 3 are preferably formed in a ring shape. The gap holding members 3 and 3 formed in a ring shape in this manner are inserted into the conductive support 1 so as to come into contact with both ends of the resistance adjustment layer 2. At this time, if the gap holding members 3 and 3 and the electric resistance adjusting layer 2 and / or the conductive support 1 are fixed with an adhesive, the gap holding members 3 and 3 are detached when used for a long period of time. Can be separated.

The material constituting the gap retaining members 3 and 3 is preferably an insulating material having a volume resistivity of 10 ¹³ Ω · cm or more. As described above, when the material constituting the gap holding members 3 and 3 is an insulating material having a volume resistivity of 10 ¹³ Ω · cm or more, a short-circuit current is generated with the base layer (not shown) of the photosensitive drum 5. Can be prevented.

  The material constituting the gap holding members 3 and 3 is not particularly limited except that it is an insulating material, but is preferably a resin material that is soft enough to not damage the photoreceptor and easy to mold. is there. Such resin materials are, for example, resins such as high-density polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), polystyrene copolymer (AS, ABS), PC, polyurethane, etc. And a resin such as a fluororesin. The gap retaining members 3 and 3 in the present invention are formed into a ring shape by molding means such as injection molding or extrusion molding.

  As shown in FIGS. 2 and 3, the groove 4 in the present invention is a portion where only the groove 4 exists in the axial direction of the conductive roller 10 at all the positions of the gap holding members 3 and 3. It is arranged at an angle θ with respect to the axis of the conductive roller 10 such that there is no such. As described above, the axis of the conductive roller 10 is such that the groove 4 has no portion where only the groove 4 exists in the axial direction of the conductive roller 10 at all the positions of the gap holding members 3 and 3. When the photosensitive member 5 falls into the concave groove 4, it is possible to prevent the occurrence of fine vibrations, so that stable image quality can be obtained. Such a concave groove 4 is formed, for example, by forming the gap holding members 3 and 3 to a predetermined size and then cutting the surface.

  In the present invention, the groove width of the concave groove 4 is larger than the toner average particle diameter. As described above, when the groove width of the concave groove 4 is larger than the average particle diameter of the toner, it is possible to prevent particles such as toner particles from staying in the concave groove and causing clogging. Thus, particles such as toner particles can be transported to the end of the conductive roller 10 satisfactorily.

In the present invention, the volume resistivity of the electric resistance adjusting layer 2 is preferably 10 ⁶ to 10 ⁹ Ωcm. When the volume resistivity of the electric resistance adjusting layer 2 exceeds 10 ⁹ Ωcm, the charging ability and the transfer capability are insufficient, and when the volume resistivity of the electric resistance adjusting layer 2 is less than 10 ⁶ , the entire photoconductor. Leakage due to voltage concentration at However, when the volume resistivity of the electric resistance adjusting layer 2 is 10 ⁶ to 10 ⁹ Ωcm as in the present invention, sufficient charging ability and transfer ability can be secured, and power concentration on the photosensitive member can be ensured. The occurrence of abnormal discharge can be prevented, and a uniform image can be obtained for them.

  The material constituting the electric resistance adjusting layer 2 is not particularly limited, but polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), polystyrene copolymer (AS, ABS) and the like, or thermoplastic resins such as PC, polyurethane and fluororesin. These resins are preferable because of good processability. As the polymer type ion conductive material dispersed in the resin, a polymer compound containing polyether ester amide is preferable. Since the polyether ester amide is an ion conductive polymer material, it is uniformly dispersed and immobilized at a molecular level in the matrix polymer. Therefore, there is no variation in electrical resistance value due to poor dispersion as seen in a composition in which an electron conductive conductive agent such as metal oxide or carbon black is dispersed. Further, since polyether ester amide is a polymer material, bleeding out hardly occurs. In order to make the electric resistance value a desired value, the blending amount thereof is preferably 30 to 70% by weight of the thermoplastic resin and 70 to 30% by weight of the polymer type ionic conductive agent.

  The resin composition constituting the electric resistance adjusting layer 2 can be easily adjusted by melt-kneading a mixture of each material with a biaxial kneader, a kneader or the like. In order to form the electrical resistance adjusting layer 2 on the conductive support 1, the semiconductive resin composition is coated on the conductive support 1 by means such as extrusion molding or injection molding. . In addition, at any stage, the surface can be cut or ground to obtain the required surface accuracy.

If only the electric resistance adjusting layer 2 is formed on the conductive support 1 to form the conductive roller 10, toner or the like may adhere to the electric resistance adjusting layer 2 and the performance may deteriorate. Such a problem can be eliminated by forming a surface layer (not shown) on the electric resistance adjusting layer 2. In the present invention, the volume resistivity of the surface layer is preferably larger than the volume resistivity of the electrical resistance adjusting layer 2. As described above, when the volume resistivity of the surface layer is larger than the volume resistivity of the electric resistance adjusting layer 2, it is possible to prevent voltage concentration and abnormal discharge from occurring on the photosensitive member defect portion. However, if the electric resistance value of the surface layer is too high, the charging ability and the transfer ability will be insufficient. Therefore, the difference in electric resistance value between the surface layer and the electric resistance adjusting layer 2 is preferably 10 ³ or less. The material for forming the surface layer is preferably a resin such as a fluorine resin, a silicone resin, a polyamide resin, or a polyester. Since these resins are excellent in non-adhesiveness, they are preferable in terms of preventing sticking of toner. Further, since such a resin is electrically insulating, the electrical resistance of the surface layer can be adjusted by dispersing various conductive materials in the resin. The surface layer is formed on the electric resistance adjusting layer 2 by preparing a paint by dissolving the resin material constituting the surface layer in an organic solvent, and applying the paint by means of spray coating, dipping, roll coating or the like. The thickness of the surface layer is preferably 10 to 30 μm.

  Since the electrical characteristics (electric resistance value) of the conductive roller 10 are important, it is necessary to make the surface layer conductive. The conductive surface layer is formed by dispersing a conductive agent in the resin material constituting the surface layer. The conductive agent is not particularly limited, but conductive carbon such as Ketjen Black EC and acetylene black, carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, oxidation treatment, etc. Carbon for color, pyrolytic carbon, indium-doped tin oxide (ITO), tin oxide, titanium oxide, zinc oxide, copper, silver, germanium, and metal oxides, polyaniline, polypyrrole, polyacetylene, etc. Examples include conductive polymers. In addition, as the conductivity imparting material, there are also ionic conductive substances, inorganic ionic conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, lithium chloride, and further modified fatty acid dimethylammonium ethosulphate. And organic ionic conductive materials such as ammonium stearate acetate and lauryl ammonium acetate.

  The conductive roller of the present invention is preferably a charging roller. Such a conductive roller can charge the surface of the photoconductor in a non-contact manner. For this reason, the charging roller can be prevented from being contaminated and the like, and the charging roller can be made of a hard material to be highly accurate. Therefore, uneven charging can be prevented.

  In the present invention, the charging roller according to claim 5 is a detachable process cartridge (see 110 in FIG. 4) provided so as to be disposed close to the member to be charged. Thus, when the charging roller according to claim 5 is a process cartridge provided so as to be disposed close to the member to be charged, stable image quality can be obtained over a long period of time, and replacement can be performed by user maintenance. Is possible and simplified.

  In the present invention, an image forming apparatus having the process cartridge according to claim 6 (see 110 in FIG. 4) is provided. As described above, with the image forming apparatus having the process cartridge according to the sixth aspect, it is possible to obtain an image with high reliability and high image quality.

  In the present embodiment, the description has been mainly given of the charging roller that embodies the conductive roller 10, but the conductive roller 10 in the present invention may be a developing roller or a transfer roller as long as it does not contradict the object of the present invention. .

(Example 1)
50% by weight of ABS resin (Denka ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 50% by weight of polyether ester amide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals Co., Ltd.) are used as a resin composition. The object was coated on a conductive support (core shaft) made of stainless steel having an outer diameter of 8 mm by injection molding to form an electric resistance adjusting layer. Then, after inserting and bonding a ring-shaped gap holding member made of high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) to the conductive support so as to contact both ends of the electric resistance adjusting layer, cutting is performed. Thus, the outer diameter (maximum diameter) of the gap holding member was set to 12.12 mm, and the outer diameter of the resistance adjusting layer was set to 12.12 mm. Next, a groove having a width of 0.02 mm and a depth of 0.02 mm was formed on the surface of the gap holding member by an inclination of 45 ° with respect to the axis (core axis) of the conductive roller at intervals of 3 mm. Subsequently, a resin composition comprising an acrylic silicone resin (3000 VH-P, manufactured by Kawakami Paint Co., Ltd.), an isocyanate curing agent, and carbon black (35% by weight with respect to the total solid content) on the surface of the resistance adjustment layer. A surface layer having a film thickness of about 10 μm was formed by (volume specific resistance: 2 × 10 ⁹ Ωcm) to obtain a conductive roller.

(Example 2)
Conductivity is the same as in Example 1 except that grooves having a width of 0.05 mm and a depth of 0.05 mm are provided on the surface of the gap holding member by tilting 60 ° with respect to the core axis at intervals of 2 mm. Got Laura.

(Example 3)
Conductivity is the same as in Example 1 except that grooves having a width of 0.2 mm and a depth of 0.2 mm are provided on the surface of the gap holding member at an interval of 3 mm with an inclination of 30 ° with respect to the core axis. Got Laura.

Example 4
Conductivity is the same as in Example 1 except that grooves having a width of 0.1 mm and a depth of 0.1 mm are provided on the surface of the gap holding member by 45 ° with respect to the core axis at intervals of 5 mm. Got Laura.

(Example 5)
Conductivity is the same as in Example 1 except that grooves having a width of 0.07 mm and a depth of 0.07 mm are provided on the surface of the gap holding member by tilting 75 ° with respect to the core axis at intervals of 3 mm. Got Laura.

(Comparative Example 1)
100 parts by weight of epichlorohydrin rubber (Epichromer CG, manufactured by Daiso Corporation) and 3 parts by weight of ammonium perchlorate are blended to form a rubber composition. This rubber composition (volume resistivity: 4 × 10 ⁸ Ωcm) is made of stainless steel. After a rubber support layer is formed by coating a conductive support (core shaft) having a diameter of 8 mm by extrusion molding, the rubber cover layer is subjected to vulcanization treatment, and then the rubber coating layer subjected to this vulcanization treatment. Was finished to an outer diameter of 12 mm by grinding to form an electric resistance adjusting layer. And on the surface of this electrical resistance adjustment layer, it consists of polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.), an isocyanate curing agent, and tin oxide (25% by weight based on the total solid content). A surface layer having a film thickness of 10 μm was formed from the resin composition (volume resistivity: 2 × 10 ¹⁰ Ωcm). Then, a tape-like member (DaiTac PF025-H, manufactured by Dainippon Ink Co., Ltd.) composed of a polyethylene terephthalate resin (PET) having a thickness of 50 μm was attached around both ends to obtain a conductive roller.

(Comparative Example 2)
ABS resin (Denka ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50% by weight, and ion conductive polymer compound containing quaternary ammonium base (Rolex AS-1720, manufactured by Daiichi Kogyo Seiyaku) 50% by weight % Resin composition (volume resistivity: 2 × 10 ⁸ Ωcm), and this resin composition is coated on a core shaft made of stainless steel with an outer diameter of 8 mm by injection molding to form a coating layer. Was finished to an outer diameter of 12.0 mm by cutting to form an electric resistance adjusting layer. And on the surface of this resistance adjustment layer, a resin composition (volume) comprising a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (45% by weight with respect to the total solid content). A surface layer having a thickness of about 10 μm was formed by a specific resistance of 2 × 10 ¹⁰ Ωcm. Next, a ring-shaped gap holding member made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) is inserted and bonded to the conductive support so as to come into contact with both ends of the electric resistance adjusting layer. A conductive roller was obtained.

(Comparative Example 3)
A resin composition (volume resistivity: 50% by weight of ABS resin (Denka ABS GR-0500, manufactured by Denki Kagaku Kogyo) and 50% by weight of polyether ester amide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals) 2 × 10 ⁸ Ω · cm), and this resin composition is coated on a conductive support (core shaft) made of stainless steel with an outer diameter of 8 mm by injection molding to form an electric resistance adjusting layer with an outer diameter of 12.0 mm. did. And on the surface of this electric resistance adjustment layer, a resin composition (fluorocarbon (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (45% by weight with respect to the total solid content) ( A surface layer having a thickness of about 10 μm was formed by volume resistivity: 2 × 10 ¹⁰ Ωcm. Next, a concave groove having a width of 0.2 mm and a depth of 0.2 mm is formed by cutting a ring-shaped gap holding member having an outer diameter of 12.12 mm made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics). Are provided at intervals of 3 mm parallel to the core axis, and ring-shaped gap holding members provided with the concave grooves are inserted and bonded to the conductive support so as to abut against both ends of the electric resistance adjusting layer. A sex roller was obtained.

(Comparative Example 4)
A ring-shaped air gap retaining member made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) with an outer diameter of 12.12 mm is cut into a groove having a width of 0.002 mm and a depth of 0.002 mm. In the same manner as in Comparative Example 3, except that the ring-shaped air gap holding member provided with the concave grooves is inserted and bonded to both ends of the electric resistance adjusting layer. Got Laura.

  As described above, the conductive members obtained in Examples 1 to 5 and Comparative Examples 1 to 4 are mounted on an image forming apparatus (see FIG. 4) as a charging member, and the gap amount between the charging member and the photosensitive member. Was measured. Next, by setting the applied voltage to DC = −800 V, AC = 2400 Vpp (frequency = 2 KHz) and passing 600,000 sheets, (1) the gap amount between the charging member and the photosensitive member, ( 2) The state of the gap holding member and (3) the image were evaluated. The evaluation environment was 23 ° C. and 60% RH, and PxP toner (particle diameter 5 μm) was used as the evaluation toner. The evaluation results are shown in the following Table 1.

  According to Table 1, in the conductive rollers obtained in Examples 1 to 5, good results were obtained in all items, but in the conductive rollers obtained in Comparative Examples 1 to 4, there were defects in the conductive members. I know that there is.

It is sectional drawing of the electroconductive roller which shows one embodiment of this invention. It is a schematic diagram which shows the state arrange | positioned on a conductive roller photoconductor drum. FIG. 3 is a partially enlarged explanatory view of the conductive roller shown in FIG. 2. It is explanatory drawing of the image forming apparatus using the conventional charging roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Electrical resistance adjustment layer 3 Gap holding part 4 Concave groove 5 Photosensitive drum G Gap 10 Conductive roller

Claims (7)

In a conductive roller having a conductive support, an electric resistance adjusting layer formed on the conductive support, and a gap holding member provided at both ends of the electric resistance adjusting layer,
The gap holding member has at least one groove on the outer peripheral surface thereof that is inclined with respect to the axis of the conductive roller, and the groove is formed by rotating the conductive roller. A conductive roller provided in a direction toward the end of the roller.   2. The conductive roller according to claim 1, wherein the gap holding member has a large number of concave grooves on the outer peripheral surface thereof that are inclined with respect to the axis of the conductive roller.   The concave groove is arranged at an angle θ with respect to the axis of the conductive roller so that there is no portion where only the concave groove exists in the axial direction of the conductive roller at all positions around the gap holding member. The conductive roller according to claim 1, wherein the conductive roller is a conductive roller.   The conductive roller according to claim 1, wherein a groove width of the concave groove is larger than a toner average particle diameter.   The conductive roller according to claim 1, wherein the conductive roller is a charging roller.   6. A process cartridge, wherein the charging roller according to claim 5 is provided so as to be disposed close to a member to be charged.   An image forming apparatus comprising the process cartridge according to claim 6.

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