JP5047647B2 - Method for manufacturing conductive member - Google Patents

Description

The present invention relates to a method for manufacturing a conductive member used as a charging member in an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

  Conventionally, in electrophotographic systems such as copying machines, laser beam printers, facsimiles, etc., a charging member that performs a charging process on an electrostatic latent image carrier (photoconductor) and a transfer process on toner on the photoconductor. A conductive member is used as a transfer member to be performed. Hereinafter, a case where a conductive member is used as the charging member will be described.

  FIG. 8 is a schematic view of an electrophotographic image forming apparatus. Referring to FIG. 8, reference numeral 101 denotes an electrostatic latent image carrier (drum-shaped photoconductor) on which an electrostatic latent image is formed. The member (charging roller) 103 is exposed to laser light or reflected light of the original, 104 is a toner carrier (developing roller) for attaching toner to the electrostatic latent image on the photosensitive member 101, and 105 is a voltage applied to the charging member 102. A voltage application power source for applying the voltage, 106 is a transfer roller for transferring the toner image on the photoconductor 101 to the recording paper 107, 107 is a recording paper conveyed from the paper supply unit, and 108 is the photoconductor 101 after the transfer processing. 109 is a surface potential meter for measuring the surface potential of the photosensitive member 101. In FIG. 8, functional units normally required in other electrophotographic processes are omitted.

In such an image forming apparatus, an image is formed by the following means.
1. A charging roller charges the surface of the photoreceptor to a desired potential.

2. An exposure device projects image light onto the photoconductor to form an electrostatic latent image corresponding to a desired image on the photoconductor.

3. The developing roller develops the electrostatic latent image with toner and forms a toner image (developed image) on the photoreceptor.

4). The transfer roller transfers the toner image on the photoconductor to the recording paper.

5). A cleaning device cleans toner remaining on the photosensitive drum without being transferred.

6). The recording paper onto which the toner image has been transferred by the transfer roller is conveyed to a fixing device (not shown). The fixing device heats and pressurizes the toner to fix it on the recording paper.

  By repeating the above steps 1 to 6, a desired image is formed on the recording paper.

  Here, as a charging method using a charging roller, there are a contact charging method in which a charging roller is brought into contact with a photosensitive member (Japanese Patent Laid-Open No. 63-149668 (Patent Document 1), Japanese Patent Laid-Open No. 1-211179 (Patent Document). 2), JP-A-1-267667 (Patent Document 3), etc.). However, the contact charging method has the following problems.

・ Charging roller trace (occurs because the material constituting the charging roller oozes out from the charging roller and moves to the surface of the charged body), charging sound (charged object when AC voltage is applied to the charging roller) (This occurs because the charging roller in contact with the device vibrates.)

Deterioration of electrical conductivity due to toner on the photoreceptor adhering to the charging roller (especially, toner adhering more easily due to the above-mentioned seepage), and adhesion of substances constituting the charging roller to the photoreceptor Permanent deformation of the charging roller that occurs when the body is stopped for a long time.

  As a method for solving such a problem, a proximity charging method in which a charging roller is brought close to a photosensitive member has been devised (Japanese Patent Laid-Open No. 3-240076 (Patent Document 4) and Japanese Patent Laid-Open No. 4-358175 (Patent Document). 5), JP-A-5-107871 (Patent Document 6) and the like). The photosensitive member is charged by applying a voltage to the charging roller so that the closest distance (gap) between the charging roller and the photosensitive member is 50 to 300 μm. In this proximity charging method, the charging device and the photoconductor are not in contact with each other, which causes problems with the contact charging device, such as “adhesion of a substance constituting the charging roller to the photoconductor”, Permanent deformation that occurs in this case is not a problem. In addition, with regard to “decrease in charging performance due to adhesion of toner or the like on the photosensitive member to the charging roller”, the proximity charging method is excellent because less toner adheres to the charging roller.

  Japanese Patent Laid-Open Nos. 3-240076 and 4-358175 disclose a method in which spacer ring layers are provided at both ends of a roller as means for holding a gap between the charging roller and the photosensitive member.

  However, these publications do not describe specific means for precisely setting the gap, and the gap varies due to variations in the dimensional accuracy of the charging roller and the spacer ring. As a result, the charged potential of the photosensitive member becomes uniform. It has a defect that it fluctuates.

  In Japanese Patent Application Laid-Open No. 2001-296723 (Patent Document 7), these problems are solved by a tape-shaped gap holding means having a predetermined thickness. However, there is a problem that the gap between the photosensitive member and the charging roller cannot be maintained in a long-term use due to the abrasion of the tape-like member, the fixing of the toner due to the protrusion of the tape adhesive, and the like. Further, due to variations in the thickness of the tape and the adhesive layer, it is not possible to form a highly accurate gap.

  In Japanese Patent Laid-Open No. 2005-091818 (Patent Document 8), a gap holding member is press-fitted into both end portions of the electric resistance adjusting layer. The configuration (relationship) between the electric resistance adjusting layer and the gap holding member is that the gap holding member is formed at the end of the electric resistance adjusting layer, and the gap holding member is in contact with the end face of the electric resistance adjusting layer and the conductive support. Yes. In order to improve long-term reliability, it is possible to secure the gap holding member by applying an adhesive between the gap holding member and the conductive support, but the gap holding member (resin) Since the linear expansion coefficient of the conductive support (metal) and the conductive support (metal) will be large, if it becomes a low temperature or high temperature environment, there is a possibility that peeling occurs at the interface between the conductive support and the gap holding member, Long-term reliability is slightly inferior. In addition, the adhesive strength is weakened by energization for a long time. When the gap holding member moves, the gap accuracy fluctuates, so that uneven charging tends to occur. In particular, when the gap is made highly accurate, it can be achieved by processing the electric resistance adjusting layer and the gap forming member at the same time. However, if the gap holding member is not sufficiently fixed, grinding, cutting, etc. Since the gap member rotates during the removal process, it is necessary to apply the adhesive and fix the gap holding member more firmly.

  The gap holding member and the electric resistance adjusting layer are formed of different materials in consideration of the toner fixing property, but since the ionic conductive agent is used as the resistance adjusting agent of the electric resistance adjusting layer, the water absorption is high and the temperature is high. When the humidity is high, the electrical resistance adjustment layer absorbs moisture and causes dimensional variation.

  Specifically, the gap holding member is made of an olefin material in consideration of insulation and toner adhesion resistance. However, since the olefin material is a low water absorption material, it is more hot and humid than the electric resistance adjustment layer. Therefore, there is a problem that a gap (step) formed with high accuracy is fluctuated due to environmental variation.

  In general, a molded article made of a resin material or a rubber material such as an electric resistance adjusting layer expands by heating, but a shrinking action occurs by cooling. Heating releases the residual stress during molding and changes the shape of the molded product. There are various ways of deformation depending on the shape of the molded product and the processing method, which cannot be generally explained, but there is a tendency for the shape to change in a direction without a binding force. Shrinkage occurs due to oxidation over time and bleeding of organic matter

  Further, when these expansion / contraction deformations occur, the position of the resin member in the axial direction changes, and the contact position with the photosensitive member changes. At the end in the axial direction, since the boundary changes between the conductive region and the insulating region of the air gap retaining function, there is a high probability that an electrical leak or an end image abnormality will occur.

  In particular, recent conductive members may be destroyed or cracked to obtain a sufficient charging function, to stabilize the electrical characteristics (electrical resistance) in the environment, to stabilize over time, and even when a high voltage is applied. It contains ionic conductive resin. By adding an ionic conductive resin, the water absorption is higher than that of a general resin, and the possibility of expansion due to water absorption is high. Moreover, although water evaporates by heating, it may not shrink to the original state. This is due to the fact that the residual stress in the molding described above is large, and it is easy to deform the molding layer in the heated and softened state (deformation in the extending direction). This is caused by the fact that the shrinkage corresponding to the amount of elongation at the time of heating cannot be achieved and the molding layer does not return completely because the friction coefficient at the interface between the cored bar and the molding layer is large. It is believed that there is.

Therefore, for a resin molding layer coated on a long metal core such as an electric resistance adjustment layer, the adhesion treatment between the metal core which is a conductive support and the electric resistance adjustment layer mainly constrains the shrinkage. Is often used. When the adhesive treatment is performed in this way, there is a load on the equipment and environment such as an adhesive application device and cleaning of the metal core, and it is also difficult to peel off the resin material and reuse the metal core. It becomes.
JP-A 63-149668 Japanese Patent Laid-Open No. 1-211179 JP-A-1-267667 Japanese Patent Laid-Open No. 3-240076 JP-A-4-358175 JP-A-5-107871 JP 2001-296723 A JP 2005-091818 A

The present invention has been made in view of the above problems, and its object is to stabilize the electrostatic latent image carrier even when used over a long period of time under environmental conditions such as high temperature and high humidity. It is an object of the present invention to provide a highly durable conductive member that maintains the air gap and can uniformly charge the surface of the electrostatic latent image carrier.

  Specifically, the electrical resistance adjusting layer forming material is hygroscopic and has a large thermal expansion, and the electrical resistance adjusting layer is molded in the longitudinal direction on the surface of the conductive support (core metal) to be long. Even if it is a case where it is a scale member, even if it does not use an adhesive agent, it aims at obtaining the conductive member of the stable shape by which the expansion-contraction was suppressed.

In order to solve the above-described problem, the conductive member of the present invention is a conductive member having a conductive support and an electric resistance adjusting layer formed on the surface of the conductive support as described in claim 1 . The conductive support has a high surface portion that is raised toward the electric resistance adjusting layer side at the center of the surface, and a low surface portion provided with a recess for fitting on the surface around the high surface portion. A step portion is formed between the surface portion and the low surface portion, and the electric resistance adjusting layer is provided on the entire high surface portion and at least a part of the low surface portion, and the surface on the conductive support side the have a fitting protrusion to be fitted into the fitting recess, the fitting concave portion is provided in a groove shape along the stepped portion, the difference in height between the high surface portion and the lower surface portion 0. 5 mm or more, a width from the stepped portion of the fitting recess is 0.5 mm or more, and the The depth of the recessed portion for fitting from the low surface portion is 0.2 mm or more, and the boundary between the high surface portion and the step portion is a curvature that is ½ of the height difference between the high surface portion and the low surface portion. R is chamfered to have a radius, and the boundary between the wall portion and the bottom surface of the fitting recess is R chamfered so that the radius of curvature is ½ of the depth of the fitting recess. A method of manufacturing a conductive member having a bottom surface of a combination recess having a length in a direction perpendicular to the stepped portion of 0.5 mm or more, wherein the electric resistance adjusting layer is an electric resistance adjusting layer forming material. A method for producing a conductive member, characterized in that it is formed by supplying a molten state to the surface of a support.
It is.

The method for producing a conductive member of the present invention, as described in claim 2, in the method for manufacturing a conductive member according to claim 1, wherein the fitting recess is provided in contact with the stepped portion It is characterized by being.

The method for producing a conductive member of the present invention, as described in claim 3, in the manufacturing method for conductive member according to claim 1 or claim 2, wherein the electrical of the surface of the conductive support A gap holding member having a height higher than the height of the electric resistance adjusting layer is provided in contact with an end of the electric resistance adjusting layer at a portion where the resistance adjusting layer is not formed.

The method for producing a conductive member of the present invention, as described in claim 4, in the method for manufacturing a conductive member according to claim 1 to claim 3, said conductive member has a cylindrical shape Features.

According to the method for producing a conductive member of the present invention , it is very easy to form the electrical resistance adjusting layer by supplying the electrical resistance adjusting layer forming material to the surface of the conductive support in a molten state. The fitting convex part can be made into a shape corresponding to the shape of the fitting concave part. At this time, a higher deformation preventing effect of the electric resistance adjusting layer can be obtained, and the following excellent conductive member can be obtained. Obtainable.
That is, a conductive member having a conductive support and an electric resistance adjusting layer formed on the surface of the conductive support, the center of the surface of the conductive support facing the electric resistance adjusting layer side. A high surface portion, a low surface portion provided with a recess for fitting on the surface around the high surface portion, a step is formed between the high surface portion and the low surface portion, and the electric The resistance adjustment layer is provided on the entire high surface portion and at least a part of the low surface portion, and has a fitting convex portion that fits into the fitting concave portion on the surface on the conductive support side. The strength of the material and the fluctuation of the shape of the electric resistance adjusting layer are suppressed, and the material for forming the electric resistance adjusting layer is hygroscopic and has a large thermal expansion. It is a case where it is molded in the upper longitudinal direction to make a long member Even, without using an adhesive, it is possible to obtain a conductive member of a stable shape in which the expansion is suppressed. When such a conductive member is incorporated in an image forming apparatus as a charging material, a stable gap is maintained between the electrostatic latent image carrier and a long-term use under severe environmental conditions. Furthermore, it is a conductive member having uniform charging on the surface of the electrostatic latent image carrier and high durability (long life).
Furthermore, according to the manufacturing method of the conductive member of the present invention, since the recess for fitting is provided in a groove shape along the stepped portion, higher strength of the electric resistance adjusting layer and a deformation preventing effect are obtained. be able to.
Further, according to the method for producing a conductive member of the present invention, the difference in height between the high surface portion and the low surface portion is 0.5 mm or more, and the width of the fitting recess from the step portion is 0.5 mm or more. And when the depth from the said low surface part of the said recessed part for fitting is 0.2 mm or more, the deformation | transformation prevention effect of an even higher electrical resistance adjustment layer can be acquired.
Furthermore, according to the method for manufacturing a conductive member of the present invention, the boundary between the high surface portion and the stepped portion has a radius of curvature that is ½ of the height difference between the high surface portion and the low surface portion. Chamfered, the boundary between the wall portion and the bottom surface of the fitting recess is rounded so that the radius of curvature is 1/2 of the depth of the fitting recess, and the bottom surface of the fitting recess is Since the length in the direction perpendicular to the stepped portion is 0.5 mm or more, stress breakdown can be prevented in advance, so that a long life can be achieved, and a higher electric resistance adjusting layer can be prevented from being deformed. Can be obtained.

Moreover, according to the manufacturing method of the electroconductive member of this invention of Claim 2, since the said recessed part for fitting is provided in contact with the said step part, the intensity | strength and deformation | transformation of a still higher electric resistance adjustment layer are provided. The prevention effect can be obtained.

Moreover, according to the manufacturing method of the electroconductive member of this invention of Claim 3 , in the electroconductive member of Claim 1 or Claim 2 , the said electrical resistance adjustment layer of the said surface of the said electroconductive support body Since the gap holding member higher than the height of the electric resistance adjusting layer is in contact with the end portion of the electric resistance adjusting layer at a portion where the gap is not formed, the shape variation including the gap holding member is reduced, and the conductive member As a function, performance does not deteriorate.

According to the method for producing a conductive member of the present invention according to claim 4 , since the conductive member has a cylindrical shape, it can be used while being rotated. At this time, the rotation causes a change with time. Therefore, it is possible to prevent the occurrence of partial occurrence of the material, and thus to achieve a long life.

  1 (a) and 1 (c) are model perspective views of examples of the conductive support used in the conductive member of the present invention, and FIGS. 1 (b) and 1 (d) show these conductive supports. A charging member obtained by attaching a gap holding member 203 to a conductive member provided with an electric resistance adjusting layer using a body is shown.

  An example 201a of a conductive support shown in FIG. 1A is obtained by applying nickel plating to the surface of a cylindrical body (columnar body) made of stainless steel, and at the center of the side surface of the conductive support 201a. The large-diameter portion 201a1 as a high-surface portion that becomes higher toward the electrical resistance adjustment layer forming side, the axial periphery of the large-diameter portion 201a1, that is, in this case, both ends are provided with recessed fittings 201a2 on the side surfaces. While having the small diameter part 201a3 as a surface part, the step part 201a4 is formed between the large diameter part 201a1 and the small diameter part 201a3.

  The fitting recess 201a2 is provided on the side surface of the small-diameter portion 201a3 in contact with the step 201a4, and a plurality of fitting recesses 201a2 (substantially rectangular recesses) are provided, and the plurality of recesses 201a2 extend along the step 201a4. Are arranged.

  The charging member shown in FIG. 1B wraps the step 201a4 on the entire large-diameter portion 201a1 and part of each of the two small-diameter portions 201a3 among the side surfaces of the conductive support 201a. Is provided with an electrical resistance adjusting layer 202a, and the fitting convexity fitted to the fitting concave portion 201a2 of the conductive support 201a on the inner side surface of the electric resistance adjusting layer 202a on the conductive support 201a side. Since the portion 202a1 is provided and the fitting recess 201a2 and the fitting projection 202a1 are fitted to each other, a restraining effect (anchor effect) is obtained against the expansion of the electric resistance adjusting layer.

  Furthermore, the small diameter part 201a3 which is the part where the electric resistance adjusting layer 202a is not formed on the side surface of the conductive support 201a is in contact with both ends of the electric resistance adjusting layer 202a, and the height (thickness) of the electric resistance adjusting layer 202a is reached. Higher (larger diameter) gap holding members 203a are respectively provided. In this example, the gap holding member 203a is bonded to the end of the electric resistance adjusting layer 202a.

  Here, when the gap holding member is disposed adjacent to the electric resistance adjustment layer, the arrangement position of the gap holding member also fluctuates due to the expansion and contraction of the electric resistance adjustment layer. Although there is a concern that a deviation occurs and a noise image due to charging unevenness or an abnormal image due to leakage occurs, the present invention solves these problems simultaneously by reducing the shape variation of the electric resistance adjusting layer.

  On the other hand, in the conductive support 201b shown in FIG. 1C, the fitting recess 201b2 has a groove shape along the two step portions 201b4 in place of the plurality of fitting recesses 201a2 in the conductive support 201a. It differs only in the point provided in.

  The charging member shown in FIG. 1D wraps the step 201a4 on the entire large diameter portion 201b1 and part of each of the two small diameter portions 201b3 on the side surface of the conductive support 201b. The electric resistance adjusting layer 202b is provided on the inner surface of the electric resistance adjusting layer 202b on the conductive support 201b side, and is fitted into the groove-like fitting recess 201b2 of the conductive support 201b. Since the convex protrusions 202b1 for fitting are provided, and the concave parts for fitting 201b2 and the convex parts for fitting 202b1 are fitted to each other, a restraining effect (anchor effect) on the expansion of the electric resistance adjusting layer is obtained. -Effect) is obtained.

  Furthermore, the small diameter part 201b3 which is a part where the electric resistance adjusting layer 202b is not formed on the side surface of the conductive support 201b is in contact with both ends of the electric resistance adjusting layer 202b, and the height (thickness) of the electric resistance adjusting layer 202b. Higher (larger diameter) gap holding members 203b are respectively provided. In this example, the gap holding member 203b is bonded to the end of the electric resistance adjusting layer 202b.

  In these examples, the electrical resistance adjustment layer is formed so as to wrap the two step portions formed between the large diameter portion and the small diameter portion, and the fitting recess and the fitting projection Thus, even in an environment and conditions that may cause a dimensional change in the electric resistance adjusting layer, the charging member has a stable shape in which expansion and contraction is suppressed without adhesion.

Here, various resin materials can be used as the gap holding member. A necessary characteristic of the gap holding member is to form a gap with the electrostatic latent image carrier stably over the environment and for a long time (time). For this purpose, moisture absorption and wear resistance are required. Small materials are desirable. It is also important that the toner and the toner additive do not adhere easily, and that the electrostatic latent image carrier is not abraded because it contacts and slides on the electrostatic latent image carrier. Accordingly, it is appropriately selected. Specifically, polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS) and copolymers thereof (AS (acrylonitrile-styrene copolymer), ABS (acrylonitrile-butadiene-styrene). Copolymer)) and other general-purpose resins, PC (polycarbonate), urethane resins, fluorine resins, and the like. In particular, in order to securely fix the gap holding member, an adhesive can be applied and bonded between the electric resistance adjusting layer and the conductive support. The gap holding member is preferably an insulating material, and preferably has a volume resistivity of 10 ¹³ Ωcm or more. The reason why insulation is necessary is to eliminate the generation of leakage current with the electrostatic latent image carrier substrate. As the gap holding member, one formed by molding is usually used.

The electric resistance adjusting layer is formed of a thermoplastic resin composition in which a polymer type ion conductive material is dispersed. The volume resistivity of the electric resistance adjusting layer is preferably 10 ⁶ to 10 ⁹ Ωcm. If it exceeds 10 ⁹ Ωcm, charging ability and transfer ability will be insufficient, and if the volume resistivity is lower than 10 ⁶ Ωcm, leakage due to voltage concentration on the entire electrostatic latent image carrier will occur.

  The thermoplastic resin used for the electric resistance adjusting layer is not particularly limited, but polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS) and a copolymer thereof (AS, A general-purpose resin such as ABS) is preferable because it can be easily molded.

  The polymer type ion conductive material dispersed in the thermoplastic resin is preferably a polymer compound containing a polyether ester amide component. Polyether ester amide is an ion conductive polymer material, and is uniformly dispersed and immobilized at a molecular level in a matrix polymer. Therefore, there is no variation in 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. In addition, since it is a polymer material, bleeding out hardly occurs. About a compounding quantity, since it is necessary to make resistance value into a desired value, it is necessary to make a thermoplastic resin into 30 to 70 weight% and a polymeric ion conductive agent to 70 to 30 weight%.

  When an ionic conductive material having a large water absorption rate is used as the resin material used for the electrical resistance adjusting layer, the water absorption rate is 3.5 to 4.1%, which is a high water absorption rate among the resin materials. Water absorption is higher than 0.4 to 0.5% of ABS resin.

  In the electric resistance adjusting layer of the conventional conductive member using such a polymer type ion conductive material, the expansion due to water absorption is about 1 mm (about 0.4%) at the maximum when the molding length is 300 mm. . Further, the entire length is not uniformly expanded, and the deformation of the member at the end portion becomes large, but the conductive member of the present invention has a high surface portion, a low surface portion and a step portion on the conductive support, and the low surface portion. A fitting convex portion that has a fitting concave portion, and the electric resistance adjusting layer is provided on the entire high surface portion and at least a part of the low surface portion, and is fitted to the concave portion for fitting on the surface on the conductive support side. Therefore, the anchor effect is generated, and such a deformation can be prevented by giving a restraining effect to the expansion of the conductive material.

  Further, with respect to thermal expansion, since expansion deformation is prevented by the fitting between the fitting convex portion and the fitting concave portion, no deformation occurs even when contracted after expansion.

  There is no restriction | limiting in particular regarding the manufacturing method of a resin composition, It can manufacture easily by melt-kneading the mixture of each material with a biaxial kneader, a kneader, etc. Formation of the electric resistance adjusting layer on the conductive support can be easily performed by coating the conductive support with the semiconductive resin composition by means such as extrusion molding or injection molding.

  If only the electric resistance adjusting layer is formed on the conductive support to constitute the conductive member, the toner, the toner additive, etc. may adhere to the electric resistance adjusting layer and the performance may deteriorate. Such a problem can be prevented by forming a surface layer on the electric resistance adjusting layer.

The resistance value of the surface layer is formed so as to be larger than that of the electric resistance adjusting layer, thereby avoiding voltage concentration and abnormal discharge (leakage) on the electrostatic latent image carrier defect portion. However, if the resistance value of the surface layer is too high, the charging ability and the transfer ability will be insufficient. Therefore, the difference in resistance value between the surface layer and the electric resistance adjusting layer is preferably 10 ³ Ωcm or less.

  As a material for forming the surface layer, fluorine-based resin, silicone-based resin, polyamide resin, polyester resin and the like are excellent in non-adhesiveness, and are preferable in terms of preventing toner sticking. Since the resin material is electrically insulating, the resistance of the surface layer is adjusted by dispersing various conductive materials in the resin.

  The surface layer is formed on the electric resistance adjusting layer by dissolving the surface layer constituting material in an organic solvent to prepare a paint, and performing various coating methods such as spray coating, dipping, and roll coating. About a film thickness, it is desirable that it is about 5-30 micrometers.

  As an example of a method for producing a conductive member, an electric resistance adjusting layer is formed on a conductive support by injection molding, and then an adhesive is applied to the step portions at both ends to bond and fix the gap holding member. . After that, in order to reduce the variation in the stepped portion between the gap holding member and the electric resistance adjusting layer, the outer diameter is removed by removing processing such as cutting and grinding in a state where the gap holding member and the electric resistance adjusting layer are integrally formed. Finish. Thereafter, a surface layer is further formed on the electric resistance adjusting layer in a state where the gap holding member is protected to obtain a conductive member.

  Thus, when the electrical resistance adjusting layer is injection-molded on the conductive support, a high surface portion that is raised toward the electrical resistance adjusting layer side at the center, and a low surface portion that is provided with a recess for fitting around the high surface portion. And forming an electric resistance adjusting layer on the entire high surface portion and at least a part of the low surface portion using a conductive support having a step portion formed between the high surface portion and the low surface portion. Thereby, the convex part for a fitting fitted to the concave part for a fitting can be easily formed in the surface at the side of an electric resistance adjustment layer conductive support.

  As the shape of the conductive support, the difference in height between the high surface portion and the low surface portion, that is, the height of the stepped portion is 0.5 mm or more, the width from the stepped portion of the fitting recess is 0.5 mm or more, and The depth from the lower surface portion of the recess for fitting is preferably 0.2 mm or more in order to obtain a sufficiently high deformation preventing effect of the electric resistance adjusting layer.

If the difference in height between the high surface portion and the low surface portion, that is, the height of the stepped portion is less than 0.5 mm, a sufficient effect may not be obtained, so that it is preferably 0.5 mm or more.
If the size of the recess for fitting (the width when the recess for fitting is groove-shaped) is less than 0.5 mm, it is not completely transferred to the molding material of the electric resistance adjusting layer, resulting in incomplete formation of the protrusion for fitting. Thus, it may be difficult to obtain the effects of the present invention. Increasing the molding resin temperature and increasing fluidity is a countermeasure, but increasing the resin temperature also has the side effect that the material tends to oxidize. The size of the fitting recess is 0.5 mm or more. Preferably there is. If the depth of the recess for fitting is less than 0.2 mm, sufficient effects may not be obtained.

  The electric resistance adjusting layer is formed on the surface of the cored bar which is a conductive support, and a conductive member can be obtained. However, the required outer diameter of the member tends to be reduced due to demands for downsizing the apparatus. In the case of a cylindrical conductive support, the total length is A3 size, 300 to 350 mm, the outer diameter is about 10 mm to 15 mm, and the bearing connection part, which is a small diameter part at the end of the conductive support, has a diameter of 5 mm to The component configuration has an elongated shape of about 8 mm.

  In that case, in order to ensure the rigidity and strength of the member, it is desirable to increase the diameter of the conductive support inside the electric resistance adjusting layer. Since the flexural rigidity changes with the fourth power of the outer diameter and the torsional rigidity changes with the third power of the outer diameter, it is desirable that the outer diameter of the core metal other than the bearing connecting portion which is a small diameter portion is 8 mm or more and 12 mm or less.

  In the conductive member of the present invention, since the rigidity of the conductive support can be increased by forming the large diameter portion, durability and dimensional accuracy can be increased.

  In addition, it is desirable to give an R shape to the step portion of the conductive support and the concave portion for fitting in consideration of the breaking strength in order to avoid stress concentration. At this time, the chamfered portion is rounded so that the boundary between the high surface portion and the step portion has a radius of curvature that is ½ of the difference in height between the high surface portion and the low surface portion, and the boundary portion between the wall portion and the bottom surface of the recess for fitting However, the curvature radius is chamfered so as to be ½ of the depth from the lower surface portion of the fitting recess, and the length of the bottom surface of the fitting recess in the direction perpendicular to the stepped portion (conductive support) When the body is cylindrical, the axial length is preferably 0.5 mm or more. By providing the recess for fitting in contact with the stepped portion, the high surface area can be increased. When the low surface area is large, the deformation of the electric resistance adjusting layer tends to be large. However, when the high surface area is large, the deformation of the electric resistance adjusting layer can be reduced. That is, it is preferable to provide the fitting concave portion and the step portion at the end of the conductive support as much as possible.

  When the fitting recess is rounded at the boundary between the wall and the bottom, increasing the R shape reduces the volume of the groove, making it difficult to achieve the effects of the present invention. In this case, the length of the bottom surface of the recess for fitting in the direction perpendicular to the stepped portion (the length in the axial direction when the conductive support is cylindrical) is 0.5 mm or more as described above. By doing so, it is possible to eliminate the influence of the R shape.

  When the electric resistance adjusting layer is formed by injection molding or extrusion molding on a cylindrical (including the case of “columnar” in the present invention), the fluidity of the material is limited in the mold, Side effects such as difficulty in flowing and increased pressure occur.

  In particular, the outer diameter of the molding does not change, and by providing the conductive support with a large diameter portion and a step portion, the resin flow path in the mold becomes narrow. Resin must be injected, and the resin residual stress increases.

  Further, since the thickness changes, a difference occurs in the cooling and solidifying behavior, and sink marks or the like in which the molded outer shape is not partially transferred to the mold are likely to occur. It is necessary to pay attention at the time of mold design and molding, and to examine in advance so as to prevent the trouble that is likely to occur by providing a large diameter portion on such a conductive support.

  FIG. 2 is a model diagram showing a state in which the conductive member shown in FIG. 1B is disposed on the electrostatic latent image carrier as a charging member. The conductive member is disposed in contact with the electrostatic latent image carrier at an arbitrary pressure. The gap holding member is formed in a non-image forming area excluding the image forming area. By applying a voltage to the charging member in this state, the electrostatic latent image carrier can be charged. When the conductive member is used as a toner carrier and a transfer member, it can be performed in the same manner.

  In the present invention, the shapes of the conductive member and the electrostatic latent image carrier are not particularly limited, and the electrostatic latent image carrier can be either a belt shape or a cylindrical shape. The conductive member can also take various shapes such as a blade shape and a cylindrical shape, and preferably has a cylindrical shape. If both are always facing each other on the same surface, chemical deterioration of the surface due to energization stress occurs, but this deterioration can be reduced by rotating both of them in a cylindrical shape. Here, when the gap holding member is in contact with the photosensitive member as shown in FIG. 2, it becomes driven rotation and the power function can be omitted.

  The conductive member of the present invention has a function of charging the photosensitive member by discharging a charge by applying a voltage. The photosensitive member to be charged functions as a charging member by maintaining a gap distance of 50 to 300 μm uniformly according to Paschen's law. Therefore, the dimension of the gap holding member is determined so that the gap is within this range.

  FIG. 3 shows a process cartridge 87 incorporating the conductive member of the present invention as a charged body. In order to replace all the parts including the electrostatic latent image carrier at the same time by inserting the conductive member into the process cartridge 87 (an apparatus including the electrostatic latent image carrier, development and cleaning) as the charging roller 82a. The image quality is stable. Replacement can also be done by user maintenance and simplified.

  The charging device 82 of the process cartridge 87 includes a charging roller 82a which is a conductive member of the present invention and a spring (not shown) for bringing the charging roller 82a into contact with the electrostatic latent image carrier 1. The charging roller 82a is connected to a power source (not shown), and a predetermined voltage is applied. Although the gap holding member of the charging roller 82a and the electrostatic latent image carrier 81 are in contact with each other, a charging cleaning roller 82b for cleaning foreign matter adhering to the surface of the charging roller 82a is provided around the charging roller 82a. ing. Thereby, the lifetime of the charging roller 82a can be extended.

  In FIG. 3, reference numeral 86 denotes a cleaning device for the process cartridge 87. The cleaning device 86 is in contact with the tip of the cleaning auxiliary agent molding 86 b and the electrostatic latent image carrier 81, and scrapes the cleaning auxiliary agent molding 86 b to obtain fine powder obtained from the electrostatic latent image carrier 81. The first brush roller 86d that is supplied to the surface, and contacts the electrostatic latent image carrier 81 on the upstream side in the transition direction of the electrostatic latent image carrier 81 from the first brush roller 86d. The disposed cleaning blade 86a is disposed upstream of the cleaning blade 86a in the transfer direction of the electrostatic latent image carrier 81, and contacts the tip of the lubricant molding 86c and the electrostatic latent image carrier 81. The second brush roller 86g and the second brush roller 86g, wherein the lubricant molding 86c is scraped to supply fine powder to the surface of the electrostatic latent image carrier 81. Remote has the electrostatic latent image bearing member 81 arranged coating blade 86h as the transition direction of the upstream side in contact with the electrostatic latent image bearing member 81. Reference numeral 86f denotes a toner recovery coil.

  The exposure device 83 irradiates the surface of the electrostatic latent image carrier 81 uniformly charged with light information corresponding to color image formation as a latent image by a known laser method. An exposure apparatus comprising an LED array and an image forming unit can also be employed.

  In the developing device 84, a developing sleeve 84 a provided with a magnetic field generating unit is disposed at a position facing the electrostatic latent image carrier 81. Below the developing sleeve 84a, there are provided two screws 84b for mixing toner introduced from a toner bottle (not shown) with the developer and pumping it up to the developing sleeve 84a while stirring. The developer composed of toner and magnetic carrier pumped up by the developing sleeve 84a is regulated to a predetermined developer layer thickness by the doctor blade 84c and is carried on the developing sleeve 84a. The developing sleeve 84 a carries and conveys the developer while moving in the direction of the arrow at a position facing the electrostatic latent image carrier 81, and supplies toner to the latent image surface of the electrostatic latent image carrier 1.

  FIG. 4 shows an example of an image forming apparatus incorporating a process cartridge incorporating the conductive member of the present invention as a charged body. By incorporating the process cartridge into the image forming apparatus to obtain an image output apparatus, it is possible to obtain an image with high reliability and high image quality.

  In FIG. 4, 100 is a copying apparatus main body, 200 is a paper feed table on which it is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 500 is an automatic document feeder (ADF) further mounted thereon. In the copying apparatus main body 100, a tandem type image forming system in which four image forming means 18 each having various means for performing an electrophotographic process such as charging, developing, and cleaning are arranged around the electrostatic latent image carrier 40 in parallel. A device 20 is provided. Above the image forming apparatus 20 is provided an exposure apparatus 21 that exposes the electrostatic latent image carrier 40 with laser light based on image information to form a latent image. Further, an intermediate transfer belt 10 made of an endless belt member is provided at a position facing each electrostatic latent image carrier 40 of the image forming apparatus 20. At a position facing the electrostatic latent image carrier 40 via the intermediate transfer belt 10, primary transfer means 62 that transfers the toner images of the respective colors formed on the electrostatic latent image carrier 40 to the intermediate transfer belt 10. Has been placed. For the developing device 4 of the image forming unit 18, the developer containing the toner is used. In the developing device 4, the developer carrying member carries and conveys the developer, and an alternating electric field is applied at a position facing the electrostatic latent image carrying body 40 to develop the latent image on the electrostatic latent image carrying body 40. To do. Since the developer is activated by applying an alternating electric field to the electrostatic latent image carrier 40 in this way, the toner charge amount distribution can be made narrower. Can be improved. Further, a process cartridge (see 87 in FIG. 3) that is integrally supported together with the electrostatic latent image carrier 40 and the developing device 4 and is detachably formed with respect to the image forming device 20 can be provided. In addition, the process cartridge may include a charging unit.

  The operation of the image forming apparatus 20 is as follows. First, a document is set on the document table 30 of the automatic document feeder 500, or after the automatic document feeder 500 is opened and the document is set on the contact glass 32 of the scanner 300, the automatic document feeder 500 is set. Close and press the document. When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 500, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. When this happens, the scanner 300 is immediately driven to run on the first traveling body 33 and the second traveling body 34. Next, light is emitted from the light source by the first traveling body 33 and reflected light from the document surface is further reflected toward the second traveling body 34 and further reflected by the mirror of the second traveling body 34 to form an image. The document is read through the lens 35 into the reading sensor 36.

  Subsequently, a start switch (not shown) is pressed, one of the support rollers 14, 15, 16 is rotated by a drive motor (not shown), and the other two support rollers are driven to rotate, thereby rotating the intermediate transfer belt 10. Let At the same time, the electrostatic latent image carriers 40 are rotated by the individual image forming means 18 to form black, yellow, magenta, and cyan monochrome images on the electrostatic latent image carriers 40, respectively. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

  On the other hand, a start switch (not shown) is pressed to selectively rotate one of the paper feed rollers 42 of the paper feed table 200 to feed out a sheet from one of the paper cassettes 44 provided in multiple stages in the paper bank 43. Sheets fed out from one of 44 are separated one by one by a separation roller 45 and put into a paper feed path 46, and the separated sheets are conveyed by a conveyance roller 47 to be fed in a copier body 100. 48, and the sheet guided to the paper feed path 48 is abutted against the registration roller 49 and stopped, or the paper feed roller 50 is rotated to feed out the sheet on the manual feed tray 51, and the sheet is fed onto this tray. The separated sheets are separated one by one by the separation roller 52 and manually fed into the paper feed path 53, and the sheet placed in the paper feed path 53 is also pushed against the registration roller 49. Stop and Te. Next, after the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22. Transfer and record a color image on the sheet.

  The image-transferred sheet thus obtained is conveyed to the secondary transfer device 22 and then sent to the fixing device 25, where heat and pressure are applied to fix the transferred image. The sheet is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the sheet discharge tray 57. Alternatively, the sheet is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and returned to the transfer position. Then, after recording an image on the back side of the sheet, the sheet on which the image is recorded is discharged onto a discharge tray 57 by a discharge roller 56. On the other hand, the intermediate transfer belt 10 after image transfer is prepared for another image formation by the image forming apparatus 20 after the residual toner remaining on the intermediate transfer belt 10 is removed by the intermediate transfer belt cleaning device 17.

Examples of the present invention are shown below together with comparative examples.
The conductive supports are all cylindrical (350 mm long) with nickel plating on the stainless steel surface and the same finish, with an axial length of 300 mm at the center and an outer diameter. To be 14 mm, ABS resin (Denka ABS GR-3000, manufactured by Denki Kagaku Kogyo) 50% by weight, polyether ester amide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals) 50% by weight, polycarbonate-glycidyl methacrylate-styrene-acrylonitrile Conductive resin composition obtained by mixing 5 parts by weight of a copolymer (Modiper CL440-G, manufactured by NOF Corporation) with 100 parts by weight of polyether ester amide and ABS resin, and then melt-kneading the mixture. (Hygroscopic and large thermal expansion) is used to insert the conductive support It provided the electrical resistance adjusting layer length 320mm in the central portion of the conductive support by injection molding to bets. In the mold used, the molding gate was provided at one end of the electric resistance adjusting layer forming cavity. Next, cutting was performed to set the outer diameter of the electric resistance adjusting layer to 12.6 mm.

  In the conductive member of Comparative Example 1, a conductive support having a uniform outer diameter as shown in a model in FIG. 5 is arranged in the center as shown in FIG. 6 in the conductive members of Comparative Examples 2 and 3. A conductive support having a large diameter portion and a small diameter portion formed at each end of the large diameter portion via a stepped portion was used. In the conductive members of Examples 1 to 3, as shown in a model in FIG. 7, a large-diameter portion is formed at the center, and a small-diameter portion is formed at both ends of the large-diameter portion via steps. A groove-shaped fitting concave portion (the bottom of the fitting concave portion is equal to the side surface of the column concentric with the small-diameter portion and the large-diameter portion) is formed in the circumferential direction along the step portion in the portion in contact with the step portion. These dimensions are listed in Table 1, respectively.

  Here, in the conductive supports of Comparative Examples 3 and 4 and Examples 1 to 3, the step-side end of the large-diameter portion is R with a curvature radius r (step R dimension) shown in Table 1. In the second and third embodiments, the chamfered portion is also chamfered with a radius of curvature r (groove R dimension) shown in Table 1 between the side surface and the bottom portion of the groove-shaped fitting recess.

Each conductive member obtained was evaluated.
Concerning the conductive member using the conductive support in which the groove-shaped fitting concave portion is formed, the fitting convex portion corresponding to the fitting concave portion is formed inside the electric resistance adjusting layer. Were fitted together.

  Next, the movement of both ends of the electric resistance adjusting layer was examined as shown in FIG. When both ends of the electrical resistance adjusting layer (one is the end that became the molding gate side during molding and the other is called the “molding non-gate side”) move to the end side of the conductive member, “+ (plus ) ”,“ − (Minus) ”when moving to the center side, measured with a caliper before and after a predetermined test, and each moved distance was calculated.

  Assuming that the image forming apparatus is used as a roll-shaped charged body, if the elongation is 0.3 mm or more, it interferes with the journal bearing. On the other hand, the shrinkage is 0.5 mm or more, and the gap holding member comes into contact with the charge layer of the photoconductor to cause damage to the charge layer of the photoconductor. “◎” as good when the shrinkage is 0.2 mm or less and the shrinkage is 0.3 mm or less, and “◯” when the elongation is 0.2 mm or less and the shrinkage is more than 0.3 mm and less than 0.5 mm. When the elongation exceeded 0.3 mm or the shrinkage exceeded 0.5 mm, it was evaluated as “x” as insufficient.

  Test conditions are 35 ° C. and 90% RH in high temperature and high humidity conditions for 1 day, then left in a normal room (room temperature) for 1 day, or heated at 80 ° C. (resin applied to form a surface layer) After that, the baking process was performed), or each of the samples was left for one month at room temperature.

  The surface layer is formed on the outer surface of the resistance adjusting layer by using an acrylic silicone resin (3000 VH-P, manufactured by Kawakami Paint), an isocyanate curing agent (manufactured by Kawakami Paint), and carbon black (30% based on the total solid content). %) Was spray-coated to form a surface layer having a film thickness of about 10 μm, and then heat treatment was performed in an oven at 80 ° C. for 1 hour to form the surface layer.

The measurement and evaluation results are also shown in Table 1.
According to Table 1, according to the present invention, even without using an adhesive and under high temperature and high humidity conditions, or even when a surface layer is formed, and even after a long time of one month, It can be seen that a conductive member having a stable shape in which the expansion and contraction of the deformation of the resistance adjustment layer is suppressed can be obtained.

  In Comparative Examples 1 to 4, the step shape needs to be 0.5 mm or more, and the shrinkage of the electric resistance adjusting layer is suppressed, but there is no effect on the elongation. It can be seen that the amount of elongation increased rather because the resin flow path in the mold became narrow, the resin pressure increased, and the residual stress increased.

(A) It is a model perspective view which shows an example of the electroconductive support body used for the electroconductive member which concerns on this invention. (B) It is model sectional drawing of the electroconductive member which concerns on this invention which has the electroconductive support body of (a). (C) It is a model perspective view which shows another example of the electroconductive support body used for the electroconductive member which concerns on this invention. (D) It is a model cross section of the electroconductive member which concerns on this invention which has the electroconductive support body of (c). It is a model figure which shows the state which has arrange | positioned on the electrostatic latent image carrier as a charging member the electroconductive member shown in FIG.1 (b). It is a model figure which shows the process cartridge which has the electroconductive member concerning this invention as a charging roller. 1 is a model diagram showing an image forming apparatus having a process cartridge according to the present invention. It is model sectional drawing which shows the electroconductive member of a comparative example. It is model sectional drawing which shows the electroconductive member of another comparative example. It is model sectional drawing which shows the electroconductive member of an Example. 1 is a schematic view of an electrophotographic image forming apparatus.

Explanation of symbols

201a, 201b Conductive support 201a1, 201b1 Large diameter part 201a2, 201b2 Fitting recess 201a3, 201b3 Small diameter part 201a4, 201b4 Step part 202a, 202b Electric resistance adjusting layer 203a, 203b Space holding member 81 Electrostatic latent image carrier 82 Charging device 82a Charging roller 83 Exposure device 86 Cleaning device 87 Process cartridge 101 Electrostatic latent image carrier

Claims (4)

Conductive support and a conductive member having an electrical resistance adjusting layer formed on the surface of the conductive support, higher toward the electric resistance adjusting layer side to the center of the surface of the conductive support A high surface portion, a low surface portion provided with a recess for fitting on the surface around the high surface portion, a step portion is formed between the high surface portion and the low surface portion, and the electric resistance adjusting layer but have a fitting protrusion to be fitted into the fitting recess in a surface of the conductive support side with provided over at least part of the the entire high-surface lower surface portion, said fitting recess Provided in a groove shape along the stepped portion, the height difference between the high surface portion and the low surface portion is 0.5 mm or more, the width of the fitting recess from the step portion is 0.5 mm or more, and The depth of the fitting recess from the low surface portion is 0.2 mm or more, and the front R-chamfering is performed so that the boundary between the high surface portion and the stepped portion has a radius of curvature that is ½ of the height difference between the high surface portion and the low surface portion, and the boundary between the wall portion and the bottom surface of the fitting recess The portion is rounded so that the radius of curvature is 1/2 of the depth of the fitting recess, and the length of the bottom surface of the fitting recess in the direction perpendicular to the stepped portion is 0.5 mm or more. A method for producing a conductive member,
The method for producing a conductive member, wherein the electric resistance adjusting layer is formed by supplying an electric resistance adjusting layer forming material to the surface of the conductive support in a molten state. The method for manufacturing a conductive member according to claim 1, wherein the recess for fitting is provided in contact with the stepped portion. A portion of the surface of the conductive support where the electrical resistance adjusting layer is not formed is in contact with an end of the electrical resistance adjusting layer and has a gap holding member higher than the height of the electrical resistance adjusting layer. The manufacturing method of the electroconductive member of Claim 1 or Claim 2. The method for manufacturing a conductive member according to claim 1, wherein the conductive member has a cylindrical shape.

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