JP2007057560A - Conductive roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller which is made lightweight inexpensively while maintaining the strength of a roll using a metallic shaft. <P>SOLUTION: The conductive roller has: a roll main body constituted by successively forming an elastic layer on the peripheral surface of a hollow or solid columnar body made of synthetic resin, and then a coating film layer on the elastic layer; and the metallic shaft piercing through the roll main body and arranged on the center axial line of the roll main body, wherein the functional part of at least one end of the metallic shaft is a component made of synthetic resin attached to the metallic shaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus.

  In an image forming apparatus using an electrophotographic system such as a copying machine or a printer, various conductive rollers are used, a charging roller for applying a charge to a latent image holding body such as a photosensitive drum, and a latent image holding. A developing roller for supplying a non-magnetic developer (toner) to the latent image holder for visualizing the latent image on the body, a toner supply roller for supplying the toner to the developing roller, and a toner on the latent image holder for paper, etc. Runs on a transfer roller used to transfer to a recording medium, an intermediate transfer roller that mediates toner, a cleaning roller that removes toner remaining on the latent image carrier, and a conductive belt used in an image forming apparatus An example thereof is a belt driving roller that can be driven or driven.

  Conventionally, as these conductive rollers, conductive rubber, polymer elastomer, and polymer foam in which conductivity is provided by blending a conductive agent on the peripheral surface of a hollow or solid cylindrical body made of synthetic resin. A roll body formed by forming a conductive elastic layer composed of, etc., and further forming a coating layer such as a resin layer on the outer periphery thereof, and a metal or synthetic material penetrating the roll body and disposed on the central axis Those having a shaft made of resin are generally used.

  The end of the shaft becomes a guide groove that supports a gear that constitutes a drive transmission system for rotating the roller, a D-cut portion from which an arc portion is omitted, or an E-ring groove or a rib provided on the drive transmission belt. This is a common part, and is a part that develops a function according to each shape.

For example, Patent Document 1 describes a gear portion of a developing roller.
Patent Document 2 describes that a resin roller is provided with a D-cut portion at the shaft end of its core.
JP-A-11-303972 JP 2001-219431 A

  If the shaft is made of metal, the above-described gear and D-cut functional portions are formed by machining, mainly cutting, the end of the metal shaft. Is a problem. In addition, it is difficult to make the shaft diameter of the penetrating portion smaller than the shaft diameter of the functional portion from the relationship of penetrating the shaft through the roll body, and therefore the shaft weight increases, so that the demand for weight reduction of the conductive roll cannot be answered. There are disadvantages. Although it is possible to cut only the shaft intermediate portion of the penetrating portion, this processing is not practical because it requires a large cost.

  In addition, when the shaft is made of synthetic resin, the functional part can be molded with the shaft, and the weight can be reduced at a low cost. However, when a load is applied to the roll, the roll is likely to bend and conductive. There was a possibility that the function of the roll might be inhibited.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a conductive roller that can realize a reduction in weight at a low cost while maintaining the roll strength of a metal shaft.

The gist of the present invention is as follows.
(1) A roll body in which an elastic layer and then a coating layer are sequentially formed on the peripheral surface of a hollow or solid cylindrical body made of synthetic resin, and a metal shaft that passes through the roll body and is disposed on the central axis thereof In a conductive roller having
A conductive roller having a functional part at at least one end of the metal shaft, the functional part being a synthetic resin part attached to the metal shaft.

(2) The conductive roller according to (1), wherein the synthetic resin part has a thickness of 0.8 mm or more.

(3) The conductive roller according to (1) or (2), wherein the synthetic resin part is formed integrally with a metal shaft in the mold when the mold is molded.

(4) The conductive roller according to any one of (1) to (3), wherein the metal shaft has a diameter of 5.0 to 7.5 mm.

  According to the present invention, while the metal shaft is employed, the functional portion on the shaft end side is formed of a synthetic resin part that is separate from the shaft. The functional part can be produced inexpensively and easily.

  In addition, since the functional part is a synthetic resin part, the weight of the functional part is reduced, thereby contributing to weight reduction of the conductive roll.

  Furthermore, since the metal shaft is inserted and arranged in the roll body, and the manufacturing procedure for attaching the synthetic resin part to the end portion of the metal shaft is followed, the diameter of the metal shaft can be determined without being affected by the functional portion. Therefore, it is possible to reduce the diameter of the metal shaft.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a conductive roller according to the present invention. The conductive roller 1 includes a roll body 2 in which an elastic layer 2b and then a coating layer 2c are sequentially formed on a peripheral surface of a hollow (or solid) cylindrical body 2a made of a synthetic resin, and the roll body 2 passes through the roll body 2. And a metal shaft 3 disposed on the central axis.

  A functional portion 4 is provided at at least one end of the metal shaft 3, usually at both ends. The functional part 4 shown in the figure has a shape for assembling to a functional part such as a snap fit or a gear (not shown) required for product functions, and plays a role of fixing, positioning, detent, and the like.

  Here, it is important that the functional part 4 is configured by attaching the synthetic resin part 5 molded according to the functional shape to the metal shaft 3. The synthetic resin part 5 is a combination of a drop-off preventing groove 5a and a D-cut part 5b, and has an insertion hole 5c for the metal shaft 3 inside the D-cut part 5b.

  The functional part 4 having such a complicated shape requires a great deal of cost to be formed by cutting a metal, but by using a synthetic resin part 5, for example, it can be produced simply and at low cost by injection molding. can do. As shown in FIG. 2, the injection molding process can be easily formed into a desired shape, unlike metal cutting, and as a result, there is an advantage that the functional part 4 can be finished lightly and inexpensively.

FIG. 2 is a cross-sectional view showing the mold 10 for molding the synthetic resin part 5 in a closed state. The mold 10 includes a cylindrical mold 11, a core mold 12, and a runner mold 13. These molds are shown in FIG. The mold 11 is configured to be opened and closed by being spaced apart from each other in the axial direction of the cylindrical mold 11. In a state where the mold 10 is closed, a synthetic resin is injected into the cavity 14 formed by the cylindrical mold 11 and the core mold 12 through the runner 15 and then cooled and solidified in the mold 10. Thus, the synthetic resin part 5 can be molded. Further, by using the hot runner method, the material in the runner 15 can be used without waste.
Incidentally, as the material of the synthetic resin component 5, the same material as that of a cylindrical body 2a of a roll to be described later can be used.

As shown in FIG. 3, the synthetic resin part 5 thus molded is inserted into the insertion hole 5c at the tip end of the metal shaft 3 penetrating the central axis of the roll main body 2, for example via an adhesive. It fixes and attaches in the insertion hole 5c. Therefore, since the metal shaft 3 may be inserted into the roll body 2 first, the diameter of the metal shaft can be arbitrarily determined without being affected by the functional portion 4. For example, if the shaft diameter is halved, the shaft weight becomes less than half, which is an extremely effective means for weight reduction.
Further, although not shown, it is usual that the synthetic resin component 5 is also attached to the rear end portion of the metal shaft 3 under the presence of an adhesive in the insertion hole 5c.

  Further, the coupling between the cylindrical body 2a and the metal shaft 3 may be usually performed by a conventional adhesive or the like, and is not particularly limited. For example, the metal shaft 3 is heated while the cylindrical body 2a is heated in an oven or the like. It is also possible to use a method in which the synthetic resin material of the cylindrical body 2a is contracted and fixed to the metal shaft 3 by passing through and then cooling.

  3 shows an example of a split type in which a plurality of cylindrical bodies 2a are combined to form a roll body 2. However, it is needless to say that an integral roll body 2 can be used. Here, the procedure for joining the plurality of cylindrical bodies 2a is not particularly limited. For example, when the cylindrical body 2a has an uneven fitting structure, the cylindrical bodies 2a are directly joined together. The roll body 2 can also be used, and if it does not have a fitting structure, the metal shaft 3 is inserted into the individual cylindrical bodies 2a in sequence and then fixed to each other with an adhesive or the like to form a roller. May be used.

  In forming the synthetic resin part 5, it is preferable that the wall thickness is 0.8 mm or more. For example, in the illustrated synthetic resin part 5, the portion where the thickness is thin is a side wall portion that defines the insertion hole 5 c, and thus the thickness of the side wall portion is set to 0.8 mm or more. This is because if the wall thickness is less than 0.8 mm, the fastening force required for inserting the metal shaft 3 is insufficient, and cracks are likely to occur. This is because there is a risk that it will not be possible to secure the above.

  Further, the synthetic resin part 5 may be produced as a single unit as shown in FIG. 2, but may be injection-molded integrally with the metal shaft 3 as shown in FIG. By performing such molding, the component 5 made of synthetic resin can be integrated with the metal shaft 3, and the components 5 and the metal shaft 3 are connected coaxially in order to couple them in the mold. It is possible to obtain a product with high accuracy.

  When the synthetic resin part 5 and the metal shaft 3 are integrated in this way, as shown in FIG. 5, the metal shaft 3 is formed from the end side of the metal shaft 3 on which the synthetic resin part 5 is not mounted. Is inserted through the central axis of the roll body 2, and the tip of the metal shaft 3 is inserted into the insertion hole 5c, and fixed and attached to the insertion hole 5c via an adhesive, for example.

  Here, the metal shaft 3 preferably has a diameter of 5.0 to 7.5 mm. That is, when the diameter of the metal shaft 3 is less than 5.0 mm, the shaft is bent and the roll is easily bent, and it is difficult to ensure the performance as the conductive roll. On the other hand, when the diameter of the metal shaft 3 exceeds 7.5 mm, the effect of suppressing the bending is saturated, so it is meaningless to make the diameter larger than 7.5 mm.

  Although the metal shaft 3 has a circular cross section, in the present invention, for example, the connection with the drive system is performed by the synthetic resin component 5, so the shape of the shaft is not particularly limited, and the cross section is An elliptical or polygonal shape can also be used.

  As this metal shaft 3, for example, a free-cutting steel of sulfur, aluminum, stainless steel, etc., which has been subjected to nickel, zinc plating or the like can be used. Of these, nickel-plated sulfur free cutting steel is recommended from the viewpoint of workability and material procurement.

  On the other hand, the cylindrical body 2a serving as the core of the roll body 2 exhibits good conductivity by using a synthetic resin containing a conductive agent, and as a result, a desired potential can be applied to the surface of the conductive roller 1. it can.

  The synthetic resin material used for the cylindrical body 2a may be any material as long as it has an appropriate strength and can be molded by injection molding or the like, and can be appropriately selected from general-purpose synthetic resins and engineering plastics. It is not done. Specifically, as an engineering plastic, for example, polyacetal, polyamide resin (for example, polyamide 6, polyamide 6 · 6, polyamide 12, polyamide 4 · 6, polyamide 6 · 10, polyamide 6 · 12, polyamide 11, polyamide MXD6) (Polyamide obtained from meta-xylenediamine and adipic acid)), polybutylene terephthalate, polyphenylene oxide, polyphenylene ether, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone , Polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, and the like. Examples of the general-purpose resin include polypropylene, acrylonitrile-butadiene-styrene (ABS) resin, polystyrene, and polyethylene. In addition, a melamine resin, a phenol resin, a silicone resin, etc. can also be used. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among the above, engineering plastics are particularly preferable, and polyacetal, polyamide resin, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, polycarbonate, and the like are preferable because they are thermoplastic and have excellent moldability and mechanical strength. . In particular, polyamide 6 · 6, polyamide MXD6, polyamide 6 · 12, or a mixed resin thereof is preferable. Although there is no problem in using a thermosetting resin, it is preferable to use a thermoplastic resin in consideration of recyclability.

  As the conductive agent, various materials can be used as long as they can be uniformly dispersed in the resin material, such as carbon black powder, graphite powder, carbon fiber, aluminum, copper, nickel, etc. A powdered conductive agent such as metal powder, metal oxide powder such as tin oxide, titanium oxide and zinc oxide, and conductive glass powder is preferably used. These may be used individually by 1 type and may be used in combination of 2 or more type. The blending amount of the conductive agent may be selected so as to obtain an appropriate resistance value according to the intended use and situation of the conductive roller, and is not particularly limited, but is usually a material of the cylindrical body 2a. It is preferable to set it as 5-40 mass% with respect to the whole, especially 5-20 mass%.

  The elastic layer 2b formed on the peripheral surface of the cylindrical body 2a is made of silicone rubber or urethane rubber containing a conductive agent, and these rubbers are made of a silicone rubber material containing a conductive agent on the peripheral surface of the cylindrical body 2a or It can be formed by spraying a paint made of a urethane rubber material.

  The conductive agent is blended for the purpose of controlling the conductivity of the elastic layer 2b. Either an electronic conductive agent or an ionic conductive agent may be used as the conductive agent. In the case of an electronic conductive agent, a carbon-based conductive agent is preferable in that high conductivity can be obtained with a small amount of addition. As the carbon-based conductive agent, ketjen black or acetylene black is preferably used, but carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, carbon for ink such as oxidized carbon black, etc. Black, pyrolytic carbon black, graphite and the like can also be used.

  Non-carbon electronic conductive agents include fine particles of metal oxides such as ITO, tin oxide, titanium oxide, and zinc oxide; metal oxides such as nickel, copper, silver, and germanium; conductive titanium oxide whiskers, conductive And transparent whiskers such as a conductive barium titanate whisker.

  Examples of ionic conductive agents include dodecyltrimethylammonium such as tetraethylammonium, tetrabutylammonium and lauryltrimethylammonium, octadecyltrimethylammonium such as hexadecyltrimethylammonium and stearyltrimethylammonium, ammonium such as benzyltrimethylammonium and modified aliphatic dimethylethylammonium. Organic ionic conducting agents such as perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkylsulfate, carboxylate, sulfonate; Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfate of alkali metal or alkaline earth metal such as sodium, calcium, magnesium It can be exemplified inorganic ion conductive agent such as phosphate salts.

  Two or more kinds of conductive agents may be used as a mixture, and in this case, the conductivity can be stably exhibited even when applied voltage changes or environmental changes occur. As an example of mixing, a carbon-based conductive agent mixed with an electronic conductive agent other than a carbon-based conductive agent or an ionic conductive agent can be used.

  The hardness of the elastic layer 2b is not particularly limited, but when the conductive roller 1 is used as a developing roller, the Asker C hardness is preferably 80 degrees or less, particularly preferably 30 to 70 degrees. In this case, if the hardness exceeds 80 degrees, the original function of the elastic layer, which is to relieve stress applied to the conductive roller and toner, cannot be expressed. For example, the contact area between the conductive roller and the latent image holding member is reduced. There is a risk that good development cannot be performed. Further, the toner is damaged, and the toner adheres to the photosensitive member or the layered blade. On the other hand, if the hardness is too low, the frictional force with the photoconductor and the layered blade increases, which may cause image defects such as jitter.

  Since this elastic layer 2b is used in contact with a photoreceptor or a layered blade, even when the hardness is set to a low hardness, it is preferable to make the compression set as small as possible, specifically 20% or less. It is preferable to do. The thickness is preferably 0.5 to 3.0 mm. This is not preferable because if the thickness is less than 0.5 mm, high circularity and low surface roughness of the cylindrical body 2a as a base material are required, and a low-hardness base material is required to increase the nip width. . On the other hand, if it exceeds 3.0 mm, the cost increases with the weight increase and the shape accuracy decreases. More desirably, the thickness is 1.0 to 2.0 mm.

  The surface roughness of the elastic layer 3 is not particularly limited, but when the conductive roller 1 is used as a developing roller, the JIS 10-point average roughness is preferably 15 μmRz or less, particularly 1 to 10 μmRz. If the surface roughness exceeds 15 μmRz, the layer thickness of the toner layer of the one-component developer (toner) and the uniformity of charging may be impaired. However, by adjusting the surface roughness to 15 μmRz or less, toner adhesion can be improved. In addition, image degradation due to roller wear during long-term use can be prevented more reliably.

  In order to increase the compatibility between the elastic layer 2b and the coating layer 2c, the coating layer 2c can be provided on the outer side in the radial direction of the elastic layer 2b in order to improve the surface property of the conductive roller and improve the durability. When silicone rubber is used for the elastic layer 2b, the main component of the coating layer 2c is preferably composed of urethane-modified acrylic resin, polyurethane resin, acrylic resin, polyamide resin, fluororesin, alkyd melamine resin, and elastic layer When urethane rubber is used as 2b, the main component of the coating layer 2c is preferably a polyurethane resin, which allows the unreacted substance in the elastic layer 2b to react with the coating layer 2c, for example, unreacted Since the reaction with the isocyanate and the like easily occurs, the growth of the coating layer 2c can be promoted.

As the conductive agent blended in the coating layer 2c, the same conductive agent blended in the elastic layer 2b can be used. Moreover, resin and particle | grains, such as spherical urethane, an acryl, a silicon | silicone, PE, PA, and a melamine, can be added in order to provide the coating layer 2c with a desired surface roughness.
The thickness of the coating layer 2c is preferably 0.005 to 0.050 mm. This is because if the thickness is less than 0.005 mm, it is difficult to obtain sufficient conductivity as a roller, and the particles for controlling the surface roughness are likely to fall off. On the other hand, if the thickness exceeds 0.050 mm, there is a risk that the cost increases with the increase in the paint and the particles controlling the surface roughness are buried and the desired surface roughness cannot be obtained.

  The conductive roller according to the present invention includes an image forming apparatus such as a plain paper copier, a plain paper facsimile machine, a laser beam printer, a color laser beam printer, a toner jet printer, a charging roller, a developing roller, a transfer roller, a developing roller, It is preferably used as an intermediate transfer roller, toner supply roller, cleaning roller, belt drive roller, paper feed roller, or the like.

It is a perspective view which shows the electroconductive roller which concerns on this invention. It is sectional drawing which shows the metal mold | die which forms parts made from a synthetic resin. It is a perspective view which shows the preparation process of an electroconductive roller. It is sectional drawing which shows the metal mold | die which forms parts made from a synthetic resin. It is a perspective view which shows the preparation process of an electroconductive roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive roller 2 Roll body 2a Cylindrical body 2b Elastic layer 2c Coating film layer 3 Metal shaft 4 Functional part 5 Synthetic resin part 5a Drop-off prevention groove part 5b D cut part 5c Insertion hole 10 Mold 11 Tube type 12 Core type 13 Runner Mold 14 Cavity 15 Runner

Claims (4)

A conductive roll having a roll body in which an elastic layer and then a coating layer are formed in order on the peripheral surface of a hollow or solid cylindrical body made of synthetic resin, and a metal shaft that passes through the roll body and is disposed on the central axis. In the sex roller
A conductive roller having a functional part at at least one end of the metal shaft, the functional part being a synthetic resin part attached to the metal shaft.   The conductive roller according to claim 1, wherein the synthetic resin part has a thickness of 0.8 mm or more.   3. The conductive roller according to claim 1, wherein the synthetic resin part is formed integrally with a metal shaft in the mold at the time of molding the mold.   The conductive roller according to claim 1, wherein the metal shaft has a diameter of 5.0 to 7.5 mm.

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