JP2006208447A - Conductive roller and its manufacturing method, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller which has an adhesive layer via a conductive adhesive layer on an outer periphery of a conductive support shaft and with which a way of handling adhesives for obtaining firm adhesive power and a coating application process can be easily managed, an adhesive defect and the corrosion of the conductive support shaft do not occur even if the conductive elastic layer expands under such an environment like at and under high temperature and high humidity, and image forming performance is not degraded when the conductive roller is attached to the image forming apparatus, a method for manufacturing the same, and the image forming apparatus having the conductive roller. <P>SOLUTION: The conductive roller 4 is constituted by providing the conductive elastic layer 2a on an outer periphery of a conductive support shaft 1, and in which the conductive elastic layer has rubber containing halogen atoms, and has a conductor adhesive layer having a phenolic resin, an epoxy resin, and a conducting agent between the conductive support shaft and the conductive adhesive layer; and the method for manufacturing the same and the image forming apparatus provided with the conductive roller are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive roller such as a charging roller, a developing roller, and a transfer roller used in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus typified by a copying machine, a printer, and a facsimile, and a manufacturing method thereof. .

  In an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus represented by a copying machine, a printer, a facsimile, and the like, a conductive roller or the like is used as a charging member on the surface of the photoconductor as a method for uniformly charging the surface of the photoconductor. A contact charging method is used in which charging is performed by contact. Such a conductive roller includes a conductive support shaft, an elastic layer integrally formed on the outer periphery thereof, and a surface layer formed on the outer periphery of the elastic layer.

  Further, the rubber composition used for the elastic layer is a method in which a conductive filler such as carbon black is added to and dispersed in the insulating rubber composition in order to achieve the desired conductivity, or to have electronic conductivity, or There is a method of selecting an ionic conductive rubber composition in which the rubber itself has polarity and exhibits conductivity. In the method in which conductive filler is added to and dispersed in insulating rubber to give electronic conductivity, the dispersion and orientation of the conductive filler affects the electrical characteristics, resulting in variations in each kneading batch. Even within the above, variations from roller to roller are likely to occur. However, in the method using the ion conductive rubber having conductivity, since it has conductivity itself, the amount of addition of a conductive agent or the like can be reduced, and thus the above-described variation does not occur. Therefore, it can be easily adjusted to the intended conductivity and can be obtained stably. Therefore, in recent years, with the improvement in performance of products, the production of rollers using an ion conductive rubber composition has increased.

  As such an ion conductive rubber composition, epichlorohydrin rubber (CO, ECO, GECO), acrylonitrile-butadiene rubber (NBR), acrylic rubber (ACM) and chloroprene rubber (CR) are generally used. Etc. In particular, epichlorohydrin rubber is preferable because of its low resistance. However, a rubber roller manufactured using such a rubber composition containing halogen has high hygroscopicity due to the high polarity of halogen atoms, and corrosion (rust) occurs on the conductive support shaft at high temperature and high humidity. In addition, adhesion failure occurs due to volume expansion of the roller. As a result, the phenomenon that the rubber roller floats from the conductive support shaft occurs, the roller shape is distorted, and a normal image may not be obtained even when assembled in the image forming apparatus.

  This conductive support shaft has been plated on the surface of a metal rod for the purpose of rust prevention and scratch resistance, but even if the conductive support shaft is plated Corrosion (rust) occurs starting from defects such as minute pinholes, resulting in poor adhesion, distortion of the roller shape, and normal images cannot be obtained even when assembled in an image forming device There is.

  As a method for maintaining a strong adhesive force and obtaining a normal image, there is a method using a phenol-based adhesive as an adhesive in a conductive rubber roller having a rubber layer mainly composed of an epichlorohydrin rubber composition (for example, a patent) Reference 1). In this method, the initial adhesive strength after molding is certainly strong, but when left in a high-temperature and high-humidity environment, corrosion (rust) of the conductive support shaft as described above occurs, and as a result, The phenomenon that the rubber roller floats from the conductive support shaft occurs, the roller shape is distorted, and a normal image cannot be obtained even when assembled in the image forming apparatus.

Further, in the rubber roller having a polyurethane rubber layer containing perchlorate on the conductive support shaft, an adhesive layer is provided as a barrier layer between the conductive support shaft and the rubber layer, and the thickness of the adhesive is 20 to 20 There is a method of solving the corrosion of the conductive support shaft by setting the thickness to 50 μm (see, for example, Patent Document 2). However, in order to obtain the effect, the thickness of the predetermined adhesive layer is necessary, so that the coating method becomes complicated and poor adhesion occurs. In addition, when left in a high temperature and high humidity environment, the conductive support shaft is corroded as described above, and as a result, the phenomenon that the rubber roller floats from the conductive support shaft occurs. The shape is distorted, and a normal image cannot be obtained even when assembled in an image forming apparatus.
Japanese Patent Laid-Open No. 10-293440 Japanese Patent Laid-Open No. 6-200921

  An object of the present invention is to solve the above-described problem, and in a conductive roller having a rubber layer on the outer periphery of a conductive support shaft via a conductive adhesive layer, for example, adhesion for obtaining a strong adhesive force The handling of the agent and the coating process can be easily managed, and even if the conductive elastic layer expands in an environment of high temperature and high humidity, there is no adhesion failure or corrosion of the conductive support shaft. An object of the present invention is to provide a conductive roller that does not deteriorate image forming performance when assembled in a forming apparatus, and a method for manufacturing the same.

  Another object of the present invention is to provide an image forming apparatus that can stably provide a high-quality electrophotographic image even in a high temperature and high humidity environment.

  In accordance with the present invention, a conductive roller having a conductive elastic layer on the outer periphery of a conductive support shaft, the conductive elastic layer having a rubber containing a halogen atom, and the conductive support shaft and the conductive There is provided a conductive roller having a conductive adhesive layer having a phenol resin, an epoxy resin and a conductive agent between elastic layers.

  Further, according to the present invention, there is provided a method of manufacturing a conductive roller in which a conductive elastic layer is provided on an outer periphery of a conductive support shaft, the conductive elastic layer having a rubber containing a halogen atom, and the conductive support shaft A conductive roller manufacturing method is provided in which a conductive adhesive having a phenol resin, an epoxy resin, and a conductive agent is applied to the outer periphery of the substrate, and a heat treatment step is included.

  Furthermore, according to the present invention, there is provided an image forming apparatus comprising the above conductive roller.

  Since the conductive roller of the present invention has the above-described configuration, in the conductive roller formed of a conductive elastic layer including a conductive adhesive layer and rubber containing at least a halogen atom on the outer periphery of the conductive support shaft, For example, the handling of the adhesive to obtain a strong adhesive force and the coating process can be easily managed, and the conductive support shaft does not corrode even in an environment of high temperature and high humidity. It has become possible to provide a conductive roller, a method for manufacturing the same, and an image forming apparatus that do not deteriorate the image forming performance when assembled in an image forming apparatus by improving expansion and adhesion failure.

  Hereinafter, embodiments of the present invention will be described in detail.

  As shown in FIG. 1, the conductive roller of the present invention comprises at least a conductive support shaft 1 and a conductive elastic layer 2a integrally formed on the outer periphery thereof. If necessary, the surface layer 3 formed on the outer periphery of the conductive elastic layer is added to a two-layer structure, the conductive support shaft 1, the conductive elastic layer 2a, the resistance layer 2b (not shown), and the surface. It may have a configuration of three or more layers including the layer 3.

  The conductive support shaft 1 used in the present invention can be used with any material as long as the conductivity and required shape accuracy are satisfied. For example, the conductive support shaft 1 is made of a metal material such as iron, copper, stainless steel, aluminum and nickel. Round bars can be used. Furthermore, for the purpose of imparting rust prevention and scratch resistance to these metal surfaces, it is preferable to perform plating so as not to impair the conductivity. There are two general plating methods: electrolytic plating and electroless plating. The latter is superior in uniformity of the plating film thickness, so high accuracy is obtained and defects such as pinholes are obtained. Therefore, it is preferably selected from the viewpoint of excellent corrosion resistance. Further, among electroless plating, electroless nickel plating is more preferably used from the viewpoint of the stability of the plating solution and cost.

  Further, the shape is not particularly limited as long as electroless nickel plating is applied, and a hollow or solid shape can be used without any problem. Also, the material is not particularly limited, and conventionally known materials such as iron or steel can be used for the conductive roller.

  The present invention also provides a member for a conductive roller having a conductive elastic layer provided on the outer periphery of a conductive support shaft, wherein the conductive elastic layer uses a rubber containing a halogen atom, and the conductive support shaft and the above A significant feature is that a conductive adhesive layer containing a phenol resin, an epoxy resin, and a conductive agent exists between the conductive elastic layers.

  In the conductive roller comprising an elastic layer containing a halogen atom, the present inventors cause the peeling of the conductive support shaft and the conductive elastic layer due to the hygroscopic property derived from polar rubber such as halogen-based rubber. I found out. In addition, as a result of investigating the factors that cause the conductive support shaft to corrode in a high temperature and high humidity environment, the support shaft portion where the roller shape is distorted always has a spot-like plating film floating. From the fact that iron halide was detected as the main component from the floating part, it was determined that the main cause of corrosion of the conductive support shaft was halogen atoms in the conductive elastic layer composition.

  As a result of intensive studies, by providing a conductive adhesive layer containing phenol resin, epoxy resin and conductive agent between the conductive support shaft and the conductive elastic layer, the handling and application process of the adhesive can be easily managed. In addition, even when the conductive elastic layer expands in an environment such as high temperature and high humidity, a conductive roller that does not cause adhesion failure or corrosion of the conductive support shaft is obtained.

  That is, a polar polymer having a halogen atom as a skeleton and a phenolic resin having a high polarity have an effect of improving adhesion, and a hydrogen halide generated from the halogen atom (for example, hydrogen chloride when the halogen atom is chlorine) and It is considered that the reaction with the oxirane ring of the epoxy resin traps the generated hydrogen halide, thereby suppressing the corrosion of the conductive support shaft and maintaining high adhesion even under high temperature and high humidity conditions. Moreover, in order to maintain the electrical characteristics as a conductive roller, this adhesive layer must contain a conductive agent.

  The thickness of such a conductive adhesive layer is preferably 2 μm or more and less than 15 μm. If the adhesive layer is less than 2 μm, the hydrogen halide trapping capability is weakened, and adhesion failure may occur when the durability test is continued for a long period of time. On the other hand, when the thickness is 15 μm or more, unevenness due to the thickness is likely to occur when the adhesive layer is applied, and adhesion failure may occur.

  Furthermore, in order to fully exhibit the effects of the present invention, the content of the phenol resin is preferably 40% by mass to 70% by mass when the solid component contained in the conductive adhesive layer is 100% by mass. If the content is less than 40% by mass, the adhesive strength may decrease when durability is continued for a long period of time. On the other hand, if the amount exceeds 70% by mass, the flexibility may be lost and the material may become brittle, and the effect of preventing corrosion may be deteriorated in an environment at high temperature and high humidity.

  Similarly, when the solid component contained in the conductive adhesive layer is 100% by mass, the content of the epoxy resin is preferably 10% by mass to 50% by mass. If the content is less than 10% by mass, the effect of trapping the hydrogen halide component is weakened, and the effect of preventing corrosion of the conductive support shaft may be reduced. On the other hand, when the amount exceeds 50% by mass, the amounts of the phenol resin and the conductive agent used together are relatively small, and it may be difficult to achieve both adhesive force and electrical characteristics.

  Similarly, when the solid component contained in the conductive adhesive layer is 100% by mass, the content of the conductive agent is preferably 10% by mass to 25% by mass. If the content is less than 10% by mass, the resistance as an adhesive layer may be non-uniform, and the electrical characteristics as a conductive roller may not be maintained. When it is used over a long period of time, stability may be deteriorated.

  Any known conductive agent can be used in the conductive adhesive layer, but carbon black and metal particles are preferable, and carbon black is particularly preferable.

  Moreover, it is preferable to add a synthetic rubber to such a conductive adhesive layer. This is to improve the heat resistance of the adhesive layer so as to increase the adhesion of the conductive elastic layer to the rubber and to withstand the heat history during the manufacturing process. Synthetic rubbers such as acrylonitrile-butadiene rubber (NBR), urethane rubber, and acrylic rubber are preferable because they have good compatibility with polymers containing halogen and are excellent in heat resistance.

  Moreover, when using such a conductive adhesive, in order to strengthen the adhesive force of a conductive support shaft surface and a conductive adhesive layer, it is preferable to heat-treat after apply | coating a conductive adhesive. . By this heat treatment, moisture contained in the conductive adhesive layer can be removed and the adhesive strength can be increased. The heating temperature at this time is preferably 100 degrees or more and 200 degrees or less. When the heating temperature is less than 100 degrees, it is difficult to remove moisture from the conductive adhesive layer, so the effect of increasing the adhesive strength is low. When the heating temperature exceeds 200 degrees, some of the components in the conductive adhesive May deteriorate, and the conductive adhesive may be deactivated.

  The method for applying the conductive adhesive to the conductive support shaft is not particularly limited. For example, a silicone rubber impregnated with a conductive adhesive by rotating the conductive support shaft chucked at both ends in the circumferential direction. Examples include a method in which a sponge, an acrylic rubber sponge, a urethane rubber sponge, or the like is pressed against the conductive support shaft. Also, a device such as a roll coater may be used as long as it can be applied to both end portions of the conductive support shaft. Also, the concentration of the conductive adhesive may be diluted to a predetermined concentration and applied as long as it has sufficient adhesive strength required as a member used in the manufacturing process and image forming apparatus.

  As the rubber composition used for the conductive elastic layer according to the present invention, a rubber composition containing a halogen atom was used in order to achieve the desired conductivity. As such a conductive rubber composition, epichlorohydrin rubber is preferable. In particular, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer has electrical characteristics depending on the copolymerization ratio of epichlorohydrin and ethylene oxide. Is preferably used because it can be adjusted.

In such a material of the conductive elastic layer, a conductive agent having an electron conduction mechanism such as carbon black, graphite and a conductive metal oxide, and a conductive agent having an ion conduction mechanism such as an alkali metal salt or a quaternary ammonium salt are included. It is preferable to adjust to less than 10 ¹⁰ Ω · cm by adding appropriately.

  The method for producing the conductive roller includes a method of press-fitting a rubber composition separately extruded into a tube shape into a conductive support shaft formed with a conductive adhesive layer, and an outer periphery of the conductive support shaft. There is a method in which a conductive adhesive layer is formed, an unvulcanized rubber is coated on the conductive adhesive layer, and a conductive elastic layer is vulcanized. Of these methods, the method of coating the conductive adhesive layer with unvulcanized rubber and vulcanizing and molding the conductive elastic layer causes a vulcanization reaction between the conductive adhesive layer and the unvulcanized rubber. As a result, a strong adhesive force can be obtained. Moreover, since there exists a merit which can manufacture a production line continuously, it is more preferable. However, in the case of this production method, more hydrogen halide generated by the vulcanization reaction is generated, so that the conductive support shaft is easily corroded. However, since the conductive adhesive layer according to the configuration of the present invention contains an epoxy group, it traps hydrogen halide, does not cause poor adhesion due to corrosion, and maintains the adhesive force, so that the strong adhesive force is maintained. can get. Therefore, the present invention provides an effective effect when the uncured rubber is coated on the conductive adhesive layer and the conductive elastic layer is vulcanized.

  The means for placing the unvulcanized rubber on the conductive support shaft is not particularly limited, but from the viewpoint of continuation of the production line or reduction of the production cost, an unvulcanized rubber composition using an extruder. At the same time as the product is extruded, the conductive support shaft is continuously passed through the crosshead die of the extruder, and the rubber composition is arranged on the circumference of the conductive support shaft to produce a roller shape. Is preferred. Alternatively, an unvulcanized raw rubber composition may be extruded into a tube shape, and a conductive support shaft coated with a conductive adhesive may be pushed into a predetermined length.

  Regarding the vulcanization method, in addition to hot-blast furnace vulcanization, conventionally known methods such as far-infrared vulcanization and steam vulcanization can be used. Further, it is also effective for a method in which unvulcanized rubber is disposed on the circumference of the conductive support shaft and is directly put into a mold cavity and vulcanized. Furthermore, even if the vulcanization conditions such as time and temperature are arbitrarily changed, the corrosion prevention effect and adhesive force of the conductive support shaft are not affected at all, so that the process can be designed freely.

  The surface layer 3 (outermost layer) in the present invention will be described. There is no restriction | limiting in particular as a material of a surface layer. As an example, a surface layer material containing a urethane bond that is advantageous for conductive properties and wear resistance, a resin having an acrylic skeleton that is advantageous for stain resistance, and the like can be given.

  Although there is no restriction | limiting in particular as a formation method of the surface layer in this invention, A predetermined thickness is used for the resin composition which comprises a surface layer from methods on a conductive elastic layer using methods, such as spray coating, dip coating, and roll coating. It is possible to form a surface layer on the conductive elastic layer by applying to the conductive layer and drying and curing at a predetermined temperature.

  The surface layer preferably has electron conductivity because the developed conductivity is less affected by the environment. Examples of the conductive agent for developing electron conductivity include metals or alloys such as carbon black, graphite, aluminum, nickel, and copper alloys, tin oxide, zinc oxide, potassium titanate, tin oxide-indium oxide, and tin oxide. -Metal oxides, such as antimony oxide complex oxide, etc. are mentioned.

  The film thickness of the surface layer when the conductive roller is produced is preferably 3 to 30 μm. If the thickness is less than 3 μm, it is difficult to adjust the resistance of the surface layer. If the thickness is greater than 30 μm, a large amount of conductive particles are required to obtain a desired resistance as a charging member, and the particles are easily aggregated.

  In addition, irregularities may be formed on the surface of the conductive roller. For example, as a method for forming irregularities, there are a method in which resin particles, carbon particles, silicon acid particles, metal oxide particles and the like are included in the surface layer, and a method in which the surface of the conductive roller is treated by mechanical polishing or the like. In addition, various particles, powders, and the like may be used alone or in combination of two or more for improving the image on the surface layer.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited at all by these examples.

Example 1
<Preparation of conductive adhesive 1>
A conductive adhesive 1 was obtained by blending 60 parts by mass of a novolak-type phenol resin, 20 parts by mass of a bisphenol A-type epoxy resin, 20 parts by mass of carbon black and 400 parts by mass of MEK (methyl ethyl ketone) and stirring at room temperature for 8 hours. .

<Application of conductive adhesive>
On the outer periphery of a steel support shaft 6 mm in diameter and 240 mm in length with electroless nickel plating having a thickness of 3 to 6 μm, the conductive adhesive 1 is applied to the center 210 mm of the support shaft using a roll coater. It apply | coated so that thickness might be set to 5 micrometers, and the conductive adhesive layer was formed on the support shaft.

<Preparation of conductive elastic layer>
Epichlorohydrin rubber terpolymer (epichlorohydrin: ethylene oxide: allyl glycidiether = 40 mol%: 56 mol%: 4 mol%) 100 parts by mass, calcium carbonate 30 parts by mass, zinc oxide 5 parts by mass, plasticizer 10 parts by weight of DOP (dioctyl phthalate), 3 parts by weight of a quaternary ammonium ion-based conductive agent, and 1 part by weight of an anti-aging agent are kneaded with an open roll for 20 minutes, and further a vulcanization accelerator DM (dibenzothiazyl sulfide) 1 Mass parts, 0.5 parts by mass of vulcanization accelerator TS (tetramethylthiuram monosulfide) and 1 part by mass of sulfur were added, and the mixture was further kneaded with an open roll for 15 minutes.

  This rubber material is extruded into a cylindrical shape having an outer diameter of 15 mm and an inner diameter of 5.5 mm by a rubber extruder, cut into a length of 250 mm, and vulcanized in steam at 160 ° C. for 40 minutes using a vulcanizing can. A rubber vulcanized tube was obtained. The support shaft was inserted into the rubber vulcanized tube and polished so that the outer diameter was 12 mm to obtain a conductive elastic layer. At this time, a wide polishing method was employed in the polishing process.

<Preparation of surface layer>
Lactone-modified acrylic polyol solution 100 parts by mass, methyl isobutyl ketone 250 parts by mass, conductive tin oxide fine particles (treated with trifluoropropyltrimethoxysilane) (average particle size: 0.05 μm, volume resistivity: 10 ³ Ω · cm) 130 parts by mass, hydrophobic silica fine particles (dimethylpolysiloxane-treated product) 3 parts by mass (average particle size: 0.012 μm, volume resistivity: 10 ¹⁶ Ω · cm), modified dimethyl silicone oil 0.08 parts by mass, crosslinked PMMA Using 50 parts by mass of fine particles (average particle size: 20.7 μm), a mixed solution was prepared using a glass bottle as a container. This was filled with glass beads (average particle diameter φ0.8 mm) as a dispersion medium so that the filling rate was 80%, and dispersed for 6 hours using a paint shaker disperser. A mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) each butanone oxime block body 1: 1 was added to the dispersion so that NCO / OH = 1.0, and a coating for the surface layer for dipping was added. Prepared. This paint is applied onto the elastic layer by dipping, air-dried for 10 minutes, and then dried at 160 ° C. for 1 hour with a heating type dryer to form a roller-shaped conductive roller by coating the surface layer. Obtained.

(Example 2)
A conductive roller was produced in the same manner as in Example 1 except that the thickness of the conductive adhesive layer was changed to 18 μm by applying a plurality of times.

(Example 3)
A conductive roller was produced in the same manner as in Example 1 except that the conductive adhesive 1 was further diluted and applied to make the thickness of the conductive adhesive layer 1.5 μm.

Example 4
<Preparation of conductive adhesive 2>
A conductive adhesive 2 was obtained by blending 75 parts by weight of a novolak-type phenol resin, 13 parts by weight of a bisphenol A-type epoxy resin, 12 parts by weight of carbon black and 400 parts by weight of MEK (methyl ethyl ketone) and stirring at room temperature for 8 hours. .

  A conductive roller was produced in the same manner as in Example 1 except that the conductive adhesive 2 was used.

(Example 5)
<Preparation of conductive adhesive 3>
25 parts by mass of novolak type phenol resin, 55 parts by mass of bisphenol A type epoxy resin, 20 parts by mass of carbon black and 400 parts by mass of MEK (methyl ethyl ketone) were blended, and the conductive adhesive 3 was obtained by stirring at room temperature for 8 hours. .

  A conductive roller was produced in the same manner as in Example 1 except that the conductive adhesive 3 was used.

(Example 6)
<Preparation of conductive adhesive 4>
53 parts by mass of novolak type phenolic resin, 17 parts by mass of bisphenol A type poxy resin and 17 parts by mass of carbon black and 13 parts by mass of acrylonitrile butadiene rubber (NBR) cut to about 1 mm are blended, and 400 parts by mass of MEK (methyl ethyl ketone) The conductive adhesive 4 was obtained by mixing, heating to 60 ° C. with a hot plate, and stirring for 3 days.

  A conductive roller was produced in the same manner as in Example 1 except that the conductive adhesive 4 was used.

(Example 7)
A conductive roller was produced in the same manner as in Example 6 except that the synthetic rubber contained in the conductive adhesive 4 was changed from NBR to urethane rubber.

(Example 8)
A conductive roller was produced in the same manner as in Example 6 except that the synthetic rubber contained in the conductive adhesive 4 was changed from NBR to acrylic rubber.

Example 9
A conductive roller was produced in the same manner as in Example 6 except that the support shaft coated with the conductive adhesive 4 was heat-treated in an oven at 120 ° C. for 1 hour.

(Example 10)
The support shaft coated with the conductive adhesive is heated in an oven at 120 ° C. for 1 hour, and after passing through a crosshead die, the support shaft is coated with unvulcanized rubber, and then placed in a hot air oven. A conductive roller was produced in the same manner as in Example 6 except that a rubber roller having a vulcanized rubber layer was produced by heating at 180 ° C. for 1 hour.

(Comparative Example 1)
A conductive roller was produced in the same manner as in Example 10, except that a phenol resin adhesive with a conductive agent added was used as the adhesive.

(Comparative Example 2)
A conductive roller was produced in the same manner as in Example 10, except that an epoxy resin adhesive with a conductive agent added was used.

(Comparative Example 3)
A conductive roller was produced in the same manner as in Example 10, except that the conductive agent was not blended in the adhesive, and only the phenol resin type + epoxy resin type was blended.

"Evaluation methods"
<Image evaluation>
The conductive roller obtained by the above production method was left in an environmental test furnace set to 40 ° C./95% RH (high temperature and high humidity condition) for one month. Thereafter, the output image was evaluated by an electrophotographic apparatus (trade name: Laser Shot LBP-2510, manufactured by Canon Inc.) having a conductive roller as a charging roller. Image evaluation was performed by forming a halftone image by applying only a DC voltage to the conductive support shaft so that the surface potential of the electrophotographic photosensitive member was −500V. In the image evaluation, no problem was indicated as ◯, and no defect was observed as x.

<Gap measurement (adhesive evaluation-1)>
When the roller expands, the adhesive force is weakened, and a gap (floating) is generated between the conductive support shaft and the conductive elastic layer. In order to measure this gap, the conductive roller obtained by the production method as described above was left in an environmental test furnace set to 40 ° C./95% RH (high temperature and high humidity conditions) for one month. This roller was incorporated in the cartridge, and the gap between the photosensitive drum and the charging roller was measured with a rubber roller gap inspection device (GM1000 manufactured by OPTRON).

  The gap is less than 1 μm, A is 1 μm or more and less than 3 μm B, 3 μm or more and less than 5 μm is C, 5 μm or more and less than 10 μm is D, and 10 μm or more is E. At this time, C or higher was set to a usable level.

<Surface Evaluation of Conductive Support Shaft ((Adhesiveness Evaluation-2)>
Similarly to the above, the conductive roller obtained by the production method was left in an environmental test furnace set to 40 ° C./95% RH (high temperature and high humidity conditions) for one month. Thereafter, the conductive elastic layer and the conductive support shaft were peeled off with a cutter, and the occurrence of corrosion (rust) on the conductive support shaft was confirmed.

  The case where there was no corrosion (rust) was marked with 軽, the case where there was a slight but no problem was marked with ○, and the case where large rust was seen and which was problematic, was marked with ×.

<Electrical characteristics evaluation>
Resistance measurement was performed using the conductive roller obtained by the manufacturing method, and evaluation was performed by a value (circumference unevenness) obtained by dividing the maximum value of the current value by the minimum value.

  FIG. 2 shows a schematic configuration of an electrical resistance measurement device for a conductive roller (an elastic layer of an electrophotographic conductive elastic member). The conductive roller 4 is pressed against the cylindrical aluminum drum 5 by pressing means (not shown) at both ends of the conductive support shaft 1, and is driven to rotate as the aluminum drum 5 is driven to rotate. In this state, a DC voltage is applied to the conductive support shaft 1 of the conductive roller 4 using the power source 6, and the voltage applied to the resistor 7 connected in series to the aluminum drum 5 is measured with a voltmeter 8. Then, the electric resistance of the conductive roller 4 is calculated. The electrical resistance value of the conductive roller is 100 V DC between the conductive support shaft and the aluminum drum using the apparatus of FIG. 2 in a normal temperature and normal humidity (N / N: 23 ° C./50% RH) environment. A voltage was applied to determine an electrical resistance value.

  The evaluation results are summarized in Table 1 below.

  Examples 1-5 compare the influence of the thickness at the time of coating, and the compounding quantity using the conductive adhesive which mix | blended the phenol resin, the epoxy resin, and the electrically conductive agent. As a result, although a gap (floating) was observed, rust did not occur, adhesion was good, and electric characteristics were good. The image evaluation was also good.

  In Examples 6 to 8, various synthetic rubbers are further blended with a phenol resin, an epoxy resin, and a conductive agent. As a result, although a gap (floating) was observed, rust did not occur, adhesion was good, and electrical characteristics were good. The image evaluation was also good.

  In Example 9, a phenol resin, an epoxy resin, and a conductive agent further blended with NBR were used as a conductive adhesive, and heat treatment was performed after the conductive adhesive was applied. As a result, although a gap (floating) was observed, rust did not occur, adhesion was good, and electrical characteristics were good. The image evaluation was also good.

  In Example 10, a conductive elastic layer was coated on a conductive support shaft, and then vulcanization molding was performed. As a result, although rust was observed slightly, no gap (floating) was observed, adhesion was good, and electrical characteristics were good. The image evaluation was also good.

  In Comparative Example 1, as a result of using a phenol resin adhesive added with a conductive agent, a large amount of partial deformation (unevenness) was confirmed on the same roller, the gap became large, and red rust occurred on the entire support shaft. In addition, since there was no adhesive force, image defects appeared remarkably.

  In Comparative Example 2, as a result of using an epoxy resin adhesive added with a conductive agent, partial deformation (unevenness) was often confirmed with the same roller, the gap became large, and there was no adhesive force. It appeared remarkably.

  In Comparative Example 3, no conductive agent was added to the adhesive, and only phenol resin and epoxy resin were added. As a result, there were no problems with respect to gaps and rust generation. After that, image defects appeared remarkably at a level that could not be used practically.

It is sectional drawing which shows schematic structure of the electroconductive roller of this invention. It is a schematic block diagram of the electrical resistance value measuring apparatus of the conductive roller of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support shaft 2a Elastic layer 3 Surface layer 4 Conductive roller 5 Aluminum drum 6 Power supply 7 Resistance 8 Voltmeter

Claims (7)

  A conductive roller provided with a conductive elastic layer on the outer periphery of a conductive support shaft, the conductive elastic layer having a rubber containing a halogen atom, and a phenol between the conductive support shaft and the conductive elastic layer A conductive roller comprising a conductive adhesive layer having a resin, an epoxy resin, and a conductive agent.   When the solid component contained in the conductive adhesive layer is 100% by mass, the phenol resin content is 40% by mass to 70% by mass, and the epoxy resin content is 10% by mass to 50% by mass. The conductive roller according to claim 1, wherein the content of the conductive agent is 10% by mass to 25% by mass.   The conductive roller according to claim 1, wherein the conductive adhesive layer further includes a synthetic rubber selected from acrylonitrile-butadiene rubber (NBR), acrylic rubber, and urethane rubber.   The conductive roller according to claim 1, wherein the halogen atom-containing rubber is epichlorohydrin rubber.   A method for producing a conductive roller in which a conductive elastic layer is provided on the outer periphery of a conductive support shaft, the conductive elastic layer having a rubber containing a halogen atom, and a phenol resin on the outer periphery of the conductive support shaft, A method for producing a conductive roller, comprising applying a conductive adhesive having an epoxy resin and a conductive agent, and having a heat treatment step.   A conductive adhesive layer is formed on the outer periphery of the conductive support shaft, and a conductive elastic layer having a rubber containing an unvulcanized halogen atom is coated on the conductive adhesive layer, and a vulcanization molding step is performed. A method for producing a conductive roller according to claim 5.   An image forming apparatus comprising the conductive roller according to claim 1.

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