JP4286728B2 - Process cartridge having conductive member, charging roller and charging roller, and image forming apparatus - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention can be applied to the electrophotographic technical field such as a copying machine, a laser beam printer, and a facsimile, and constitutes a facing shaft portion that is opposed to the surface of the photoreceptor so as to hold a predetermined gap. A conductive support that extends in the axial direction and to which a predetermined potential is applied, a resistance adjustment layer that is formed so as to surround the peripheral surface of the conductive support, and that adjusts the electrical resistance, and the resistance adjustment The opposing shaft portion of the photoconductor is disposed on the conductive support so as to face both ends of the layer and is made of a different material from the resistance adjusting layer and is in contact with the photoconductor. The present invention relates to a conductive member provided with a gap holding member that opens a predetermined gap to the surface and faces the surface, and more particularly, to a process roller and an image forming apparatus having a charging roller and a charging roller.

  Conventionally, in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, and a facsimile, a charging member that charges a photosensitive drum (image carrier) and toner on the photosensitive drum are used. A conductive member is used as a transfer member that performs the transfer process.

  FIG. 1 shows an example in which a conductive member is used as a charging member. A charging roller 2 in the image forming apparatus 1 is used as a charging member. The image forming apparatus 1 includes a photosensitive drum 4 on which an electrostatic latent image is formed, a charging roller 2 that performs a charging process on the photosensitive drum 4, and a power pack (for applying voltage to the charging roller 2). A voltage application power source 3, a surface potential meter 5 for measuring the surface potential of the photosensitive drum 4, a developing roller 6 for fixing toner to the electrostatic latent image on the photosensitive drum 4, and a toner image on the photosensitive drum 4. Is provided with a transfer roller 7 for transferring the toner image onto the recording paper S and a cleaning device 8 for cleaning the photosensitive drum 4 after the transfer process. As shown in FIG. 2, a process cartridge 9 having the photosensitive drum 4, the charging roller 2, the developing roller 6, and the cleaning device 8 collectively may be installed in the image forming apparatus 1.

  The charging roller 2 is supplied with power from the power pack 3 and charges the photosensitive drum 4 to a desired potential. The photosensitive drum 4 is rotated in the direction of arrow A by a driving mechanism (not shown). The surface potential meter 5 is provided immediately after the charging roller 2 along its rotation direction, and measures the potential of the surface 4 a of the photosensitive drum 4.

  The developing roller 6 causes the toner to adhere to the charged photosensitive drum 4, and the transfer roller 7 transfers the toner attached to the photosensitive drum 4 to the recording paper S. The cleaning device 8 removes the toner remaining on the photosensitive drum 4 and cleans the photosensitive drum 4.

  In the image forming process by the image forming apparatus 1, first, the surface 4 a of the photosensitive drum 4 is charged to a negative high potential by the charging roller 2. Subsequently, the charged surface 4a is irradiated with an exposure L made of reflected light from the original or laser light. This exposure L has a light amount distribution corresponding to the black / white of the image to be formed, and the potential (negative potential) of each part of the surface 4a is lowered according to the amount of received light, whereby the light amount distribution is applied to the surface 4a. Is formed, that is, an electrostatic latent image is formed.

  When the photosensitive drum 4 rotates and the portion of the surface 4a where the electrostatic latent image is formed passes through the developing roller 6, toner corresponding to the potential distribution adheres to the surface 4a, and the electrostatic latent image becomes a toner image. Is visualized as This toner image is transferred to the recording sheet S fed at a predetermined timing by the transfer roller 7, and the recording sheet S is conveyed in the direction of arrow B toward a fixing unit (not shown).

  On the other hand, after the transfer, the photosensitive drum 4 is cleaned by removing the toner remaining on the surface 4a by the cleaning device 8, and the residual charge is removed by a quenching lamp (not shown), and the process proceeds to the next image forming process. To do.

As a general charging method in the image forming apparatus 1 described above, a contact charging method in which the charging roller 2 is brought into contact with the photosensitive drum 4 is known (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).
JP-A 63-149668 Japanese Patent Laid-Open No. 1-211179 JP-A-1-267667

  However, when the charging roller 2 of the contact charging system is used, there are the following problems.

  (1) The constituent material of the charging roller oozes out from the charging roller and adheres to the surface of the photosensitive drum. When the fixing progresses, a trace of the charging roller remains on the surface of the photosensitive drum.

  (2) When an AC voltage is applied to the charging roller, the charging roller in contact with the photosensitive drum vibrates and a charging sound is generated.

(3) The toner on the surface of the photosensitive drum adheres to the charging roller and the charging performance is deteriorated.
In particular, when the dyeing of (1) occurs in the charging roller, the toner is more easily fixed.

  (4) Substances constituting the charging roller are likely to adhere to the photoreceptor.

  (5) If the photosensitive drum is not driven for a long time, the charging roller is permanently deformed.

  In order to cope with such a problem, a proximity charging method has been devised in which the charging roller 2 is brought close to the photosensitive drum 4 instead of contacting it (Japanese Patent Laid-Open No. 3-240076, etc.). In this proximity charging method, the charging roller 2 and the photosensitive drum 4 are opposed to each other so that the closest distance (hereinafter referred to as a gap) is 0.005 to 0.3 mm, and a voltage is applied to the charging roller 2. Thus, the photosensitive drum 4 is charged. In the proximity charging method, the charging roller 2 and the photosensitive drum 4 are not in contact with each other. Therefore, the problem occurs in the contact charging method, “fixing of the constituent material of the charging roller to the photosensitive drum” and “non-use for a long period of time”. “Permanent deformation of the charging roller” is not a problem. In addition, regarding the “decrease in charging performance of the charging roller due to toner adhesion”, the proximity charging method is excellent because less toner adheres to the charging roller.

  As a method for realizing the proximity charging method, a method of providing a gap at a constant interval between the charging roller and the photosensitive drum by winding a tape-like gap holding means having a predetermined thickness around both ends of the charging roller, For example, it is devised in JP-A-5-107871. However, the gap between the photosensitive drum and the charging roller may be kept at a constant interval when used for a long period of time due to wear of the tape-like member, toner penetration / fixation between the charging roller and the tape-like member, etc. There was a problem that it was difficult.

  In addition, in order to prevent abrasion of the tape-like member, a method of using a metal ring instead of the tape member is conceivable. However, in this case, since the photosensitive drum is extremely worn, the base metal of the photosensitive member and the metallic ring are used. There has been a problem that a short current is generated between the ring and a problem such as destruction of the power pack (voltage applied power source) may occur.

  Further, in order to maintain a gap between the charging roller and the photosensitive drum, a method of providing a spacer ring layer at both ends of the charging roller is disclosed in, for example, Japanese Patent Laid-Open Nos. 3-240076 and 4-358175. It has been devised. However, these publications do not disclose a specific method for keeping the gap accurately and constant, and the gap varies due to variations in the dimensional accuracy of the charging roller and the spacer ring layer. There was a problem that the charged potential of the drum was not constant.

  In addition, since the coefficient of linear expansion between the resistance adjustment layer, the conductive support and the gap holding member is greatly different, the interface between the resistance adjustment layer, the conductive support and the gap holding member in a low or high temperature environment. Peeling occurs.

  Therefore, a gap is generated between the resistance adjustment layer and the gap holding member in the firing step of the manufacturing process or in a long-term use environment of the conductive support member. If toner particles or the like enter and adhere to this gap, the gap between the photoreceptor and the charging roller cannot be maintained.

  The present invention has been made in view of the above-mentioned problems, and can maintain a uniform gap with the photoreceptor even when used for a long period of time, has high durability, and particularly prevents toner sticking. It is an object of the present invention to provide a conductive member, a charging roller, a process cartridge including the charging roller, and an image forming apparatus.

The conductive member according to claim 1 extends in the axial direction and is applied with a predetermined potential so as to constitute an opposing shaft portion opposed so as to hold a predetermined gap with respect to the surface of the photoreceptor. A conductive support, a resistance adjusting layer that is formed so as to surround the peripheral surface of the conductive support, and adjusts the electrical resistance, and the conductive support facing both ends of the resistance adjusting layer. And a gap that is made of a different material from the resistance adjustment layer and that makes the opposed shaft portion face the surface of the photoconductor by opening a predetermined gap when contacting the photoconductor A holding member,
The conductive support includes a small-diameter portion that is supported by a bearing portion, a large-diameter portion that is provided in a portion corresponding to the opposed shaft portion and prevents the resistance adjusting layer from coming off in an axial direction, and the small-diameter portion. The medium diameter part is provided between the large diameter part and the gap holding member is inserted,
The gap holding member is bonded to at least one of the resistance adjusting layer and the conductive support, and the viscosity of the adhesive is 100 mPa · s or less.
The conductive member according to claim 2 is characterized in that the adhesive is cyanoacrylate.
According to a third aspect of the present invention, in the conductive member according to the third aspect, at least an end face adjacent to the resistance adjusting layer has an insulating property.
The conductive member according to claim 4 is characterized in that the resistance adjusting layer and the gap holding member have a cylindrical shape with the conductive support as a central axis.
The charging roller according to claim 5 extends in the axial direction and is applied with a predetermined potential so as to constitute an opposing shaft portion opposed to the surface of the photosensitive member so as to hold a predetermined gap. A cylindrical conductive support, a resistance adjustment layer that is formed so as to surround the peripheral surface of the cylindrical conductive support, and adjusts the electrical resistance, and faces the both ends of the resistance adjustment layer. The opposing shaft portion is formed on a columnar conductive support and made of a different material having an insulating property that is separate from the resistance adjusting layer and is in contact with the photoconductor. A gap holding member that opens a predetermined gap and opposes it,
The cylindrical conductive support includes a small-diameter portion that is supported by a bearing portion, a large-diameter portion that is provided in a portion corresponding to the opposed shaft portion and that prevents the resistance adjustment layer from coming off in the axial direction, and the small-diameter portion. A medium-diameter portion that is provided between the portion and the large-diameter portion and into which the gap holding member is inserted,
The gap holding member is bonded to at least one of the resistance adjusting layer and the cylindrical conductive support, and the viscosity of the adhesive is 100 mPa · s or less.
A process cartridge according to a sixth aspect includes the charging roller according to the fifth aspect.
An image forming apparatus according to a seventh aspect includes the process cartridge according to the sixth aspect.

Invention of Claim 1 → Because an adhesive having a viscosity of 100 mPa · s or less is used, it can be applied thinly and uniformly over the entire adhesive surface, and the gap holding member and the resistance adjusting layer, or the gap holding member and the conductivity It is possible to bond firmly while eliminating gaps between the supports.
As a result, toner particles and the like can be prevented from entering and fixing between the resistance adjustment layer and the gap holding member, and the resistance adjustment layer is prevented from coming off in the axial direction by the large diameter portion of the conductive support. Therefore, coupled with the effect of the adhesive, the gap between the photosensitive member and the conductive member can be stably maintained during long-term use.
According to the invention of claim 2, since a high adhesive strength can be obtained in a short time by using a cyanoacrylate-based adhesive, a gap is generated between the resistance adjusting layer and the gap holding member in the manufacturing process. Rotation / detachment of the gap holding member during grinding can be prevented.
According to the third aspect of the present invention, when a voltage is applied to the conductive member, leakage from the gap holding member to the photosensitive member can be prevented.
Since the invention according to claim 4 can prevent chemical deterioration of the surface of the conductive member due to energization stress due to continuous energization from the same location by rotating the conductive member, It is possible to extend the life of the adhesive member.
The invention according to claim 5 can provide a charging roller capable of obtaining excellent image quality over a long period of time.
The invention according to claim 6 can provide a proximity charging type process cartridge capable of obtaining excellent image quality over a long period of time, and the invention according to claim 7 can provide a proximity charging type image forming apparatus.

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

  FIG. 3 is a cross-sectional view illustrating a configuration of a conductive member used as the charging roller 2 of the image forming apparatus 1. Note that the specific configuration of the image forming apparatus 1 is the same as that described in the background art with reference to FIG. 1, and thus detailed description thereof is omitted.

  The charging roller 2 is of a proximity charging type, and includes a conductive support 10 and a resistance adjusting layer 11 that is formed so as to surround an outer peripheral surface thereof and adjusts an electric resistance. The resistance adjustment layer 11 has a pair of gap holding members 12 at both ends in the axial direction.

  Between the pair of gap holding members 12 is an opposed shaft portion 11A that is opposed to the surface 4a of the photoreceptor 4 so as to hold a predetermined amount of gap G (see FIG. 6). The gap G is formed when the pair of gap holding members 12 abut on the surface 4 a of the photoreceptor 4.

  The conductive support 10 is composed of a cylindrical core bar that extends in the axial direction in order to form the opposed shaft portion 11A, and the cylindrical core bars are supported at bearings (not shown) provided at both ends thereof. The intermediate size between the small-diameter portion 10A and the large-diameter portion 10B, which is provided in a portion corresponding to the opposed shaft portion 11A, and prevents the resistance adjustment layer 11 from coming off in the axial direction. Medium diameter part 10C. A power pack (voltage application power source) 3 for applying a voltage to the charging roller 2 is connected to the small diameter portion 10A.

  The resistance adjustment layer 11 has a cylindrical shape with the conductive support 10 as a central axis. The gap holding member 12 is continuously ground or polished from one end to the other end in the axial direction so that a height difference is formed between the gap holding member 12 and the opposed shaft portion 11A. ing.

As the material of the resistance adjustment layer 11, a thermoplastic resin composition in which a polymer type ion conductive material is dispersed is used. The volume resistivity value of the resistance adjusting layer 11 is preferably 10 ⁶ Ωcm to 10 ⁹ Ωcm. This is because if the volume resistivity exceeds 10 ⁹ Ωcm, charging ability and transfer ability are insufficient, and if it is lower than 10 ⁶ Ωcm, leakage due to voltage concentration on the photosensitive member 4 occurs.

  For the thermoplastic resin composition, polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), copolymers thereof (AS, ABS), and the like can be used. Any thermoplastic resin composition is preferred because it can be easily molded.

  The polymer ion conductive material is preferably an ion conductive polymer compound containing a polyether ester amide component. Polyether ester amide is an ion conductive polymer material that is uniformly dispersed and fixed at the molecular level in the matrix polymer. Therefore, an electroconductive conductive agent such as a metal oxide or carbon black, or a conductive pigment can be used. This is because there is almost no variation in volume specific resistance value due to poor dispersion that occurs when dispersed in a thermoplastic resin composition, and bleeding out hardly occurs.

  The blending amount of the thermoplastic resin composition and the polymer type ion conductive material is determined from the viewpoint of obtaining a desired volume resistivity value, and the thermoplastic resin composition is 30 to 70% by weight (polymer type) with respect to the total weight. The ion conductive material is about 70 to 30% by weight). If a compatibilizing agent is added to the matrix polymer, the polymer type ion conductive material can be evenly dispersed at the micro molecular level.

  For mixing the thermoplastic resin composition and the polymeric ion conductive material, a melt kneading machine such as a biaxial kneader or a kneader is used, but the invention is not limited to this.

  The resistance adjusting layer 11 is formed by enclosing the mixture on the outer peripheral surface of the conductive support 10 as described above, and each means of extrusion molding and injection molding is used for the enclosing enclosure. be able to.

  A surface layer 11B is formed on the outer peripheral surface of the resistance adjusting layer 11 at a portion corresponding to the opposed shaft portion 11A from one end side in the axial direction toward the other end side. The reason why the surface layer 11B is formed is that there is a possibility that the toner and its additive adhere to the outer peripheral surface of the resistance adjusting layer 11 to deteriorate the electrical characteristics. The surface layer 11B serves to prevent the toner from sticking.

The surface layer 11B has an electric resistance larger than the volume specific resistance value (electric resistance) of the resistance adjusting layer 11 and smaller than the electric resistance of the insulating layer. If the volume resistivity value of the surface layer 11B is the same as or smaller than the volume resistivity value of the resistance adjustment layer 11, voltage concentration and abnormal discharge (leakage) are likely to occur on the defective portion of the photoreceptor 4. is there. On the other hand, if the volume specific resistance value of the surface layer 11B is too high, the charging ability is insufficient or the transfer ability is insufficient, so the difference between the electric resistance of the surface layer 11B and the electric resistance of the resistance adjusting layer 11 is 10 ³ Ωcm or less is desirable.

The gap holding member 12 has a volume resistivity of 10 ¹³ Ωcm or more from the viewpoint of preventing short circuit with respect to the photoreceptor 4, and more preferably has an insulating property and does not damage the photoreceptor 4. From the viewpoint of being soft and easy to mold, it is desirable to manufacture using a thermoplastic resin such as high density polyethylene.

  The charging roller 2 is, for example, a cylindrical cored bar (conductive support) for constituting a portion corresponding to the opposed shaft portion 11A that is opposed to the surface of the photoreceptor 4 so as to hold a predetermined gap G. A step of grinding the body 10) to form a center (see FIG. 4 (a)), and a resistance adjusting layer 11 for adjusting the electrical resistance by injection molding on the outer peripheral surface of the cylindrical core metal that has been ground. A step of forming (see FIG. 4B), a step of annealing after forming the resistance adjusting layer 11 (not shown), and inserting the gap holding member 12 into the middle diameter portion 10C of the cylindrical cored bar. Then, the conductive support 10 is rotated after bonding with the adhesive 13 using the adhesive 13 to bond the gap holding member 12, the medium diameter portion 10C, and the resistance adjusting layer 11 (see FIG. 4C). The gap holding member 12 and the resistance adjusting layer 11 are A step of forming a height difference between the gap holding member 12 and the resistance adjusting layer 11 by continuously grinding or polishing from the one end side toward the other end side (see FIG. 4D); It is manufactured through a process of forming the surface layer 11B on the resistance adjusting layer 11 in a state where the gap holding member 12 is masked, and a baking process (not shown) of removing the masking and heating and curing the surface layer 11B.

  The surface layer 11B is formed on the resistance adjustment layer 11 by preparing a paint by dissolving a material described later used in the formation of the surface layer 11B in an organic solvent, and applying various coating methods such as spray coating, dipping, and roll coating. Can be used. Note that fluorine resin, silicone resin, polyamide resin, polyester resin, or the like can be used for the surface layer 11B, and these are desirable from the viewpoint of excellent non-adhesiveness and prevention of toner sticking.

  An adhesive 13 having a viscosity of 100 mPs or less is used as the adhesive 13 used for bonding the gap holding member 12 and the end face portion of the resistance adjusting layer 11 and bonding the gap holding member 12 and the medium diameter portion 11C. With an adhesive having a viscosity greater than 100 mPs, if an adhesive having a viscosity greater than 100 ms is used, it can be applied thinly and evenly to the end face of the gap holding member 13, the end face of the resistance adjusting layer 11, and the medium diameter portion 10 </ b> C. This is because adhesion failure occurs.

As a result, a thick portion and a thin portion of the adhesive 13 and a portion where the adhesive 13 is not applied are generated, and the gap 14 is enlarged between the gap holding member 12 and the resistance adjustment layer 11 in FIG. As shown. Further, since there is uneven adhesion, a high bonding strength cannot be obtained, and there is a problem that a gap 14 is generated during the baking process at the stage of manufacturing the charging roller 2 or during long-term use of the charging roller 2. . If there is such a gap 14 in the charging roller 2, there is a disadvantage that the toner adheres to the gap 14 and the gap G cannot be maintained at a predetermined amount.

  This type of adhesive 13 desirably has a high adhesive strength within a short time after bonding, and is preferably a cyanoacrylate-based material. In the case where the time until the adhesive 13 is cured and the adhesive strength is increased is long, the gap is caused by the processing impact applied to the conductive support 10, the resistance adjusting layer 11, and the gap holding member 12 in the manufacturing stage of the conductive member 2. While the holding member 12 may rotate relative to the conductive support 10 and the resistance adjusting layer 11, when the cyanoacrylate adhesive 13 is used, high adhesive strength can be obtained within a short time after bonding. This is because such a problem can be avoided.

  FIG. 6 is a schematic view showing a state where the charging roller 2 shown in FIG. 3 is installed adjacent to the photosensitive drum 4. The charging roller 2 is disposed in contact with the photosensitive drum 4 with a predetermined pressure. In the charging roller 2, the outer diameter of the opposed shaft portion 11 </ b> A is slightly smaller than the outer diameter of the gap holding member 12. Although the outer peripheral surface of the gap holding member 12 of the charging roller 2 is in contact with the surface 4a of the photosensitive drum 4, there is a difference in height between the gap holding member 12 and the opposed shaft portion 11B. A gap G is formed between the four surfaces 4a.

  The amount of the gap G between the opposed shaft portion 11B and the surface of the photosensitive drum 4 is desirably 100 μm or less. This is because if the amount of the gap G is increased, the voltage applied to the conductive support 10 must be increased, and if the voltage applied to the conductive support 10 is increased, the photosensitive drum 4 is electrically deteriorated. This is because abnormal discharge tends to occur.

  The charging roller 2 is installed such that the gap holding member 12 is in contact with a photosensitive layer application region (non-image forming region X2) other than the image forming region X1 of the photosensitive drum 4. By applying a voltage to the charging roller 2 in this state, the image forming region X1 of the photosensitive drum 4 is charged.

  Here, the photosensitive drum 4 having a cylindrical shape is used. However, the photosensitive drum 4 may have a belt shape, and the conductive member 2 may not be cylindrical. The sex members 2 are preferably cylindrical.

  This is because, when charging is performed with the same surface of the conductive member and the photosensitive drum 4 always facing each other, chemical deterioration due to energization stress is caused by the surface of the conductive member and the photosensitive drum 4. Although it occurs on the surface 4a, if the charging roller 2 and the photosensitive drum 4 are formed in a cylindrical shape and are driven to rotate, the surfaces facing each other can be changed with rotation. This is because the chemical deterioration of the product becomes difficult to occur and the product life can be increased. The rotation driving direction of the charging roller 2 may be the same as or opposite to the rotation driving direction of the photosensitive drum 4, and the charging roller 2 is driven to rotate at the same speed as that of the photosensitive drum 4 or intermittently. Also good.

  In these examples, the three members are bonded between the gap holding member 12 and the resistance adjusting layer 11 and between the gap holding member 12 and the medium diameter portion 10C. A configuration in which only the gap holding member 12 and the middle diameter portion 10C are bonded as shown in FIG. 7, and an adhesive 13 is used only between the gap holding member 12 and the resistance adjusting layer 11 as shown in FIG. Any structure that adheres to each other may be adopted.

Below, an experimental example and a comparative example are shown. Here, the conductive members having the same structure are mainly compared by changing the viscosity of the adhesive 13, but the comparative example 1 is intentionally compared with a different structure.
<Experimental example 1>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) consisting of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, from the high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) while facing both end surfaces of the resistance adjustment layer 11 on the medium diameter portion 10C of the conductive support 10 of the molded body thus obtained. A ring-shaped gap holding member 12 was inserted.

  Subsequently, the space | gap holding member 12 was adhere | attached on 10 C of intermediate diameter parts and the resistance adjustment layer 11 using the cyanoacrylate type adhesive agent 13 (1781, the 3 bond company make). Next, one end of the gap holding member 12 is continuously rotated using a grinding tool while rotating the molded body so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. As shown in FIG. 4C and FIG. 4D, the height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

Subsequently, on the surface of the resistance adjusting layer 11, a mixture (surface resistance: 35% by weight with respect to the total solid content) made of acrylic silicon resin (3000VH-P, manufactured by Kawakami Paint Co., Ltd.), isocyanate curing agent, and carbon black. 2 × 10 9 Ω), a surface layer 11B having a thickness of about 10 μm was formed, and a conductive member 2 shown in FIG.
<Experimental example 2>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) consisting of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, from the high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) while facing both end surfaces of the resistance adjustment layer 11 on the medium diameter portion 10C of the conductive support 10 of the molded body thus obtained. A ring-shaped gap holding member 12 was inserted.

  Subsequently, the space | gap holding member 12 was adhere | attached on 10 C of medium diameter parts and the resistance adjustment layer 11 using the cyanoacrylate type adhesive agent 13 (EE, the Arteco company make). Next, one end of the gap holding member 12 is continuously rotated by using a grinding tool so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. As shown in FIG. 4C and FIG. 4D, the height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

Subsequently, on the surface of the resistance adjusting layer 11, a mixture (surface resistance: 35% by weight with respect to the total solid content) made of acrylic silicon resin (3000VH-P, manufactured by Kawakami Paint Co., Ltd.), isocyanate curing agent, and carbon black. 2 × 10 9 Ω), a surface layer 11B having a thickness of about 10 μm was formed, and a conductive member 2 shown in FIG.
<Experimental example 3>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) consisting of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Subsequently, the medium diameter part 10C of the conductive support 10 of the molded body thus obtained is made of a high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) facing both end surfaces of the resistance adjusting layer 11. A ring-shaped gap holding member 12 was inserted.

  Next, the gap holding member 12 was bonded to the medium diameter portion 10 </ b> C and the resistance adjustment layer 11 using a cyanoacrylate adhesive 13 (CN2, manufactured by Arteco). Next, one end side is continuously rotated while rotating the molded body so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer is 12.00 mm using a grinding tool. As shown in FIG. 4C and FIG. 4D, the height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

Subsequently, on the surface of the resistance adjusting layer 11, a mixture (surface resistance: 35% by weight with respect to the total solid content) made of acrylic silicon resin (3000VH-P, manufactured by Kawakami Paint Co., Ltd.), isocyanate curing agent, and carbon black. The surface layer 11B having a film thickness of about 10 μm was formed by 2 × 10 9 Ω), and the conductive member 2 shown in FIG.
<Experimental example 4>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) consisting of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, a ring made of high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) facing the both end faces of the resistance adjusting layer 11 on the medium diameter portion 10C of the conductive support 10 of the molded body thus obtained. The gap holding member 12 was inserted, and the gap holding member 12 was bonded to the medium diameter portion 10C and the resistance adjustment layer 11 using a cyanoacrylate adhesive 13 (1782, manufactured by Three Bond).

  Next, one end of the gap holding member 12 is continuously rotated while rotating the molded body so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. By cutting from the side toward the other end as shown in FIG. 4C and FIG. 4D, a height difference was formed between the gap holding member 12 and the resistance adjusting layer 11.

Next, on the surface of the resistance adjusting layer 11, a mixture (surface resistance: 2 ×) composed of acrylic silicon resin (3000VH-P, manufactured by Kawakami Paint), an isocyanate curing agent, and carbon black (35% by weight based on the total solid content). 109Ω), a surface layer 11B having a thickness of about 10 μm was formed, and a conductive member 2 shown in FIG. 3 was obtained through a firing process.
<Experimental example 5>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (Denka ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyetheresteramide (IRGASTAT P18, A resin composition (volume resistivity: 2 × 10 8 Ωcm) composed of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, a high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.) is applied to the medium-diameter portion 10C of the conductive support 10 of the molded body thus obtained so as to face both end surfaces of the resistance adjustment layer 11. A ring-shaped gap holding member 12 made of the above was inserted, and the gap holding member 12 was bonded to the medium diameter portion 10C and the resistance adjustment layer 11 using a cyanoacrylate adhesive 13 (CN4, manufactured by Arteco).

  Next, one end of the gap holding member 12 is continuously rotated while rotating the molded body so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. By cutting from the side toward the other end as shown in FIG. 4C and FIG. 4D, a height difference was formed between the gap holding member 12 and the resistance adjusting layer 11.

Subsequently, on the surface of the resistance adjusting layer 11, a mixture (surface resistance: 35% by weight with respect to the total solid content) made of acrylic silicon resin (3000VH-P, manufactured by Kawakami Paint Co., Ltd.), isocyanate curing agent, and carbon black. The surface layer 11B having a film thickness of about 10 μm was formed by 2 × 10 9 Ω), and the conductive member 2 shown in FIG.
<Comparative example 1>
A rubber composition in which 3 parts by weight of ammonium perchlorate is blended with 100 parts by weight of epichlorohydrin rubber (Epichromer CG, manufactured by Daiso Corporation) as a resistance adjusting layer 11 on a core shaft (outer diameter 8 mm) made of stainless steel as the conductive support 10. A product (volume resistivity: 4 × 10 8 Ωcm) was formed through extrusion and vulcanization processes, and finished to an outer diameter of 12 mm by grinding. Next, on this surface, a mixture (surface resistance: 2) composed of polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight based on the total solid content). The surface layer 11B having a film thickness of 10 μm was formed by × 1010Ω. Next, a tape-like member 15 (DaiTac PF025-H, manufactured by Dainippon Ink Co., Ltd.) having a thickness of 50 μm is wound around and pasted around the both ends with a one-component epoxy-containing resin adhesive (2202, manufactured by Three Bond). Through the firing step, a conductive member 2 ′ shown in FIG. 8 was obtained.
<Comparative example 2>
Ionic conductivity containing a stainless steel core shaft (outer diameter 8 mm) as the conductive support 10, 50% by weight of ABS resin (GR-0500, manufactured by Denki Kagaku Kogyo) as the resistance adjustment layer 11, and a quaternary ammonium base. A resin composition (volume specific resistance: 2 × 10 8 Ωcm) consisting of 50% by weight of a polymer compound (Roleex AS-1720, manufactured by Daiichi Kogyo Seiyaku) was formed by injection molding.

  Next, the conductive support 10 of the molded body thus obtained is made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) with both end faces of the resistance adjustment layer 11 facing the medium diameter portion 10C. The ring-shaped gap holding member 12 was inserted, and the gap holding member 12 was bonded to the medium diameter portion 11C and the resistance adjusting layer 11 with a one-component epoxy-compound resin adhesive 13 (2202, manufactured by Three Bond).

  Next, using a grinding tool, the molded body is continuously rotated from one end side while rotating the molded body so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjustment layer is 12.00 mm. By cutting toward the other end side as shown in FIGS. 4C and 4D, a height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

Next, on the surface of the resistance adjustment layer 11, a mixture (surface resistance: 2) made of a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight with respect to the total solid content). The surface layer 11B having a film thickness of about 10 μm was formed by × 1010Ω, and the conductive member 2 shown in FIG.
<Comparative Example 3>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) made of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, the conductive support 10 of the molded body thus obtained is made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) with both end faces of the resistance adjustment layer 11 facing the medium diameter portion 10C. The ring-shaped gap holding member 12 was inserted and adhered to the medium diameter portion 10C and the resistance adjustment layer 11 with a synthetic rubber adhesive 13 (1521, manufactured by Three Bond).

  Next, one end of the gap holding member 12 is continuously rotated by using a grinding tool so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. As shown in FIG. 4C and FIG. 4D, the height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

Next, on the surface of the resistance adjustment layer 11, a mixture (surface resistance: 2) made of a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight with respect to the total solid content). A surface layer 10B having a film thickness of about 10 μm was formed by × 1010Ω, and the conductive member 2 shown in FIG.
<Comparative example 4>
Stainless steel core shaft (outer diameter 8 mm) as conductive support 10, ABS resin (DENKA ABS GR-0500, manufactured by Denki Kagaku Kogyo Co., Ltd.) 50 wt% as resistance adjustment layer 11, polyether ester amide (IRGASTAT P18) A resin composition (volume resistivity: 2 × 10 8 Ωcm) made of 50% by weight (manufactured by Ciba Specialty Chemicals) was formed by injection molding.

  Next, the conductive support 10 of the molded body thus obtained is made of polyamide resin (Novamid 1010C2, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) with both end faces of the resistance adjustment layer 11 facing the medium diameter portion 10C. The ring-shaped gap holding member 12 was inserted, and the gap holding member 12 was bonded to the medium diameter portion 10 </ b> C and the resistance adjustment layer 11 with a one-component moisture-curing elastic adhesive 13 (1530, manufactured by Three Bond).

  Next, one end of the gap holding member 12 is continuously rotated by using a grinding tool so that the outer diameter (maximum diameter) of the gap holding member 12 is 12.12 mm and the outer diameter of the resistance adjusting layer 11 is 12.00 mm. As shown in FIG. 4C and FIG. 4D, the height difference was formed between the gap holding member 12 and the resistance adjustment layer 11.

  Next, on the surface of the resistance adjustment layer 11, a mixture (surface resistance: 2) made of a fluororesin (Lumiflon LF-600, manufactured by Asahi Glass Co., Ltd.), an isocyanate curing agent, and tin oxide (60% by weight with respect to the total solid content). The surface layer 11B having a film thickness of about 10 μm was formed by × 1010Ω, and the conductive member 2 shown in FIG.

Table 1 shows a comparison result between the experimental example and the comparative example at the manufacturing stage.
In Experimental Examples 1 to 5, there were no defects at the manufacturing stage, but in Comparative Examples 1 to 4, rotation / detachment of the gap holding member 12 occurred. The detached ones were re-adhered, but after firing, all the conductive members 2 of Comparative Examples 1 to 4 were arranged in Table 1 between the end face of the gap holding member 12 and the end face of the resistance adjusting layer 11. As shown, gaps occurred during the manufacturing stage.

  This is presumably because the comparative examples 1 to 4 had insufficient adhesive strength between the end face of the gap holding member 12 and the end face of the resistance adjusting layer 11 or there were unbonded portions.

以上の導電性部材を帯電ローラ２として、図１に示す画像形成装置に搭載し、帯電ローラ２と感光体４の間の空隙量Ｇを測定した。 次いで、印加電圧をＤＣ＝−８００Ｖ、ＡＣ＝２４００Ｖpp(周波数＝２kHz)に設定して、６００，０００枚を通紙し、帯電ローラ２と感光体４の間の空隙量Ｇ、抵抗調整層１１と空隙保持部材１２との間の隙間の状態、及び空隙保持部材１２の状態、及び画像について評価を行った。評価環境は２３℃、６０%RHで評価用トナーとして、ＰｘＰトナー（粒径５μｍ）を用いた。 以上の評価結果を表２に示す。 実験例１〜５の帯電ローラ２は評価項目の全てについて良好な結果が得られたが、比較例１〜４では評価項目の全てについて不具合が見られた。

The above conductive member was mounted as the charging roller 2 in the image forming apparatus shown in FIG. 1 and the gap amount G between the charging roller 2 and the photosensitive member 4 was measured. Next, the applied voltage is set to DC = −800 V, AC = 2400 Vpp (frequency = 2 kHz), 600,000 sheets are passed, the gap amount G between the charging roller 2 and the photoreceptor 4, and the resistance adjustment layer 11. The state of the gap between the gap holding member 12, the state of the gap holding member 12, and the image were evaluated. The evaluation environment was 23 ° C. and 60% RH, and PxP toner (particle diameter 5 μm) was used as an evaluation toner. The above evaluation results are shown in Table 2. In the charging rollers 2 of Experimental Examples 1 to 5, good results were obtained for all the evaluation items, but in Comparative Examples 1 to 4, defects were observed for all of the evaluation items.

  As described above, as is clear from the comparison results between the experimental example and the comparative example, good results are obtained for the adhesive 13 having a low viscosity, and it is expected that the viscosity of the adhesive 13 is preferably 100 mPa · s or less. .

It is explanatory drawing which shows an example of an image forming apparatus. It is explanatory drawing which shows the other example of an image forming apparatus. It is sectional drawing which shows an example of the electroconductive member concerning this invention. It is explanatory drawing which shows an example of the manufacturing process of the electroconductive member concerning this invention, Comprising: It is a side view of a cylindrical cored bar. It is explanatory drawing which shows an example of the manufacturing process of the electroconductive member concerning this invention, Comprising: It is a side view which shows the molded object which formed the resistance adjustment layer in the surrounding surface of the cylindrical core metal shown to FIG. It is explanatory drawing which shows an example of the manufacturing process of the electroconductive member concerning this invention, Comprising: The space | interval holding member was inserted and supported facing the both ends of the resistance adjustment layer in the cylindrical core metal, and the state fixed with the adhesive agent FIG. It is explanatory drawing which shows an example of the manufacturing process of the electroconductive member concerning this invention, Comprising: It is a figure which shows the state in the middle of cutting the molded object shown to FIG. 4c. It is a fragmentary sectional view for demonstrating the malfunction of adhesion | attachment with a space | gap holding member and a resistance adjustment layer. It is explanatory drawing which shows the state which has arrange | positioned on the photoreceptor as a charging member the electroconductive member shown in FIG. It is explanatory drawing which shows the other example of the adhesion | attachment method of a space | gap holding member, a resistance adjustment layer, and a medium diameter part, Comprising: (FIG. 7a) is the fragmentary sectional view which shows the state which adhere | attached the space | gap holding member only to the medium diameter part, FIG. 7B is a partial cross-sectional view showing a state in which the gap holding member is bonded only to the resistance adjustment layer. It is a side view which shows an example of the electroconductive member of a comparative example, and shows the state which wound the tape around the both ends of the resistance adjustment layer, and formed the resistance adjustment layer.

Explanation of symbols

4 ... Photoconductor 10 ... Conductive support 11 ... Resistance adjustment layer 11A ... Opposing shaft 12 ... Gap holding member 13 ... Adhesive G ... Gap

Claims (7)

A conductive support that extends in the axial direction and is applied with a predetermined potential in order to form an opposed shaft portion that faces the surface of the photoreceptor so as to hold a predetermined gap, and the conductive support A resistance adjusting layer formed so as to surround the peripheral surface of the body and adjusting the electric resistance; and provided on the conductive support so as to face both ends of the resistance adjusting layer and separate from the resistance adjusting layer A gap holding member which is made of a material different from the body and which makes the opposed shaft portion face the surface of the photosensitive member by opening a predetermined gap when contacting the photosensitive member,
The conductive support includes a small-diameter portion that is supported by a bearing portion, a large-diameter portion that is provided in a portion corresponding to the opposed shaft portion and prevents the resistance adjusting layer from coming off in an axial direction, and the small-diameter portion. The medium diameter part is provided between the large diameter part and the gap holding member is inserted,
The gap holding member is bonded to at least one of the resistance adjusting layer and the conductive support, and the viscosity of the adhesive is 100 mPa · s or less.   The conductive member according to claim 1, wherein the adhesive is cyanoacrylate-based.   3. The conductive member according to claim 1, wherein at least an end surface adjacent to the resistance adjusting layer has an insulating property.   The conductive member according to claim 1, wherein the resistance adjusting layer and the gap holding member have a cylindrical shape having the conductive support as a central axis. A cylindrical conductive support that extends long in the axial direction and is applied with a predetermined potential in order to form an opposing shaft portion that faces the surface of the photoreceptor so as to hold a predetermined gap, and the circle A resistance adjusting layer which is formed so as to surround the peripheral surface of the columnar conductive support and adjusts the electrical resistance;
The resistance adjustment layer is provided on the cylindrical conductive support so as to face both end portions, and is made of a different material having an insulating property separately from the resistance adjustment layer, and is in contact with the photoreceptor. A gap holding member that faces the surface of the photosensitive member by opening a predetermined gap with the opposed shaft portion;
The cylindrical conductive support includes a small-diameter portion that is supported by a bearing portion, a large-diameter portion that is provided in a portion corresponding to the opposed shaft portion and that prevents the resistance adjustment layer from coming off in the axial direction, and the small-diameter portion. A medium-diameter portion that is provided between the portion and the large-diameter portion and into which the gap holding member is inserted,
The charging roller, wherein the gap holding member is bonded to at least one of the resistance adjusting layer and the cylindrical conductive support, and the viscosity of the adhesive is 100 mPa · s or less. A process cartridge having the charging roller according to claim 5 . An image forming apparatus having the process cartridge according to claim 6 .

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