JPH10293440A - Electrifying roller member and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying roller member which has excellent adhesive property on the contact face of the electrifying roller provided with a conductive elastic layer in the outer perifery of a conductive supporting shaft, uniform electric characteristics on the elastic layer surface and excellent durability, and to provide its producing method. SOLUTION: An epichlorohydrin rubber is used for the conductive elastic layer, and the conductive elastic layer is adhered to the conductive supporting shaft with a phenol conductive adhesive. The electric resistance between the surface of the phenol conductive adhesive and the conductive supporting axis is controlled to <=5 Ω, and the phenol conductive adhesive layer is formed to 3 to 10 μm thickness. In the production process, the phenol conductive adhesive is applied to the outer perifery of the conductive supporting shaft and the subjected to preliminary heating before the adhesive is brought into contact with the epichlorohydrin rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging roller member used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and a method of manufacturing the same.

[0002]

2. Description of the Related Art
In an electrophotographic image forming apparatus represented by the Carlson process, a method for uniformly charging the surface of a photoconductor is used.
A contact charging method in which a charging member, for example, a charging roller, a charging blade, a charging brush, or the like is brought into contact with the surface of the photoreceptor to perform a charging process is used. This contact charging method has the advantage that the voltage applied to the charging member is small and the amount of ozone generated is very small.However, the contact state with the photoconductor is better when using the charging roller than using the charging blade or charging brush. Stabilize.

Incidentally, the above-mentioned charging roller has a medium resistance of 10 ⁶ to 10 ⁹ Ωcm around the outer periphery of a conductive metal core.
Are formed. The medium resistance is used to improve charging efficiency and prevent charging failure such as voltage drop due to leakage to a photoconductor defect. Epichlorohydrin rubber, ethylene propylene rubber, or the like is used as a material for forming the medium resistance elastic layer.

[0004] Conventionally, there are both cases where the core is bonded to the elastic layer as described above with an adhesive, and cases where the core is not bonded (for example, after the elastic layer is formed into a tube shape, the core is pressed into the core). . When an adhesive is not used, it is difficult to set the press-fitting margin at the time of press-fitting the metal core. In other words, when the press-fit margin is small, a slip occurs between the core metal and the elastic layer during the outer diameter grinding of the roller in the processing step, a chatter pattern is generated by the outer diameter grinding on the outer peripheral surface of the roller, and the roller is used as a charging roller. Sometimes, this pattern causes image unevenness. Even if there is no problem at first, slip may occur as the charging roller is used. If there is a large amount of press-fit, the charging characteristics may change over time after the start of use due to not only the load of the press-fitting device and deformation of the metal core but also internal strain in the elastic layer.

[0005] Even in the case where an adhesive is used, if there is a minute separation between the core metal, the adhesive layer and the elastic layer, chattering occurs at the time of grinding the outer diameter of the roller as described above, and the charging characteristics over time. Degradation and image defects.

Therefore, the present invention provides a charging roller having a conductive elastic layer provided on the outer periphery of a conductive support shaft, which has excellent adhesion on the contact surface of the charging roller and uniform electric characteristics regardless of the location on the surface of the elastic layer. It is an object of the present invention to provide a charging roller member having excellent durability and a method of manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a charging roller member comprising a conductive elastic layer provided on an outer periphery of a conductive supporting shaft in order to achieve the above object. In the charging roller member, epichlorohydrin rubber is used as the conductive elastic layer, and the conductive support shaft and the conductive elastic layer are bonded with a phenol-based conductive adhesive.

According to a second aspect of the present invention, the electric resistance between the surface of the phenolic conductive adhesive and the conductive support shaft is set to 5Ω or less.

According to a third aspect of the present invention, the thickness of the phenolic conductive adhesive layer is 3 to 10 μm.

According to a fourth aspect of the present invention, there is provided a method of manufacturing any one of the above-mentioned members for a charging roller, wherein a phenolic conductive adhesive is applied to the outer periphery of the conductive support shaft, and then the phenolic conductive adhesive is brought into contact with epichlorohydrin rubber. It is characterized in that preheating is applied before the heating.

That is, the use of epichlorohydrin rubber for the elastic layer in the charging roller member according to the present invention does not use a conductive dispersant such as carbon black, or even if it is used, only a small amount of compounding is required. This is because image defects due to insufficient nip width between the photosensitive member and the charging roller due to an increase in roller hardness due to the introduction of the agent can be suppressed. For example, in order to form a desired medium resistance roller using ethylene propylene rubber, it is necessary to add a conductive dispersant, and a softener is added to avoid the above-mentioned increase in hardness. This softener bleeds over time and precipitates on the roller surface, which contacts the photoconductor and becomes charged,
A defect such as a white stripe appears on the image. If epichlorohydrin rubber is selected, a medium resistance roller can be obtained without the addition of a conductive dispersant.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and Examples of the present invention will be described below. First, φ8mm S
Using US303, the surface of the metal core was subjected to sandblast treatment to make the surface roughness of the metal core Rz 5 μm, and then washed with trichlene to obtain a clean state. Thereafter, Examples 1 to 9 and Comparative Example 1 shown in Table 1 below were used. The adhesive type, electrical resistance, adhesive film thickness, and heating conditions after applying the adhesive (in the case of heating, use an electric furnace) were created under the conditions of ~ 3, and the adhesiveness and rubber outer diameter grinding were made respectively. Chatter of time, initial image unevenness,
The adhesiveness after paper passing was examined. The electric resistance is 17m
m was wound around the surface of the core metal coated with the adhesive so as not to float, and the resistance was measured by measuring the resistance between the core metal journal portion to the portion where the adhesive was not applied and the metal foil.

[0013]

[Table 1]

After kneading the epichlorohydrin rubber,
Rubber was wound around the outer periphery of the cored bar after application of the adhesive with a crosshead extruder as described above, and after vulcanization, a roller having an outer diameter of 16 mm was obtained. After that, a roller having a diameter of 14 mm was formed by outer diameter grinding, and then a charging roller surface layer was formed by spray-coating a nylon-based paint. As for the rollers using the urethane-based adhesive and the acrylic-based adhesive in Table 1, after extruding epichlorohydrin rubber in a tube shape (straight extrusion), after applying the adhesive, a core metal was pressed into the core, and then cured (60). C. for 1 hour), but the adhesion was insufficient.

In the charging rollers according to Examples 1 to 6, appropriate selection of the core metal, the adhesive, and the elastic layer became possible, and a good charging roller member having uniform charging characteristics including durability was obtained. However, from Table 1, it can be seen that the roller obtained by applying pre-heating after applying the adhesive to the core metal using the phenol adhesive and then vulcanizing the epichlorohydrin rubber to the vulcanized adhesive, including the adhesion at the time of durability, is good. Recognize. It is expected that it is better to make a final curing reaction after temporarily maintaining the adhesion between the core metal and the adhesive by preheating the adhesive. In addition, the electric resistance was 5 Ω or less, and the image was good without occurrence of image unevenness.
In the case of Example 8, a chattering pattern occurred during the grinding of the rubber roller, and also occurred in the image. In the case of Example 7, delamination occurred between the adhesives after the durability test. This is because the film thickness was too large.

Although only the charging roller is described in the present specification, the present invention can be applied to a medium resistance roller such as a transfer roller and a developing roller. The "roller" can include these medium resistance rollers.

[0017]

According to the charging roller member according to the first aspect, as described above, stable charging characteristics can be obtained by selecting epichlorohydrin rubber, and the initial and durability can be improved by using a phenolic conductive adhesive. Excellent adhesion can be achieved, and there is an effect that uniform charging characteristics without image unevenness can be obtained, including no chattering during roller grinding and conductivity.

In the charging roller member according to the second aspect, as described above, the electric resistance between the surface of the phenol-based conductive adhesive and the conductive support shaft is set to 5Ω or less, thereby achieving the above-mentioned common effect. In addition, there is an effect that uniform charging can be performed over the entire surface of the roller, which can ignore resistance unevenness in the elastic layer.

In the charging roller member according to the third aspect, as described above, by setting the film thickness of the phenolic conductive adhesive layer to 3 to 10 μm, in addition to the above-mentioned common effects, it is possible to include durability. This has the effect of ensuring a high degree of adhesion and obtaining a stable image.

As described above, in the charging roller member according to the fourth aspect, the adhesion between the core metal and the adhesive layer is particularly increased by the preliminary heating of the adhesive, thereby preventing chattering and durability during roller grinding. There is an effect that is improved.

Claims (4)

[Claims] 1. A charging roller member having a conductive elastic layer provided on the outer periphery of a conductive support shaft, wherein epichlorohydrin rubber is used as the conductive elastic layer, and the conductive support shaft and the conductive elastic A charging roller member wherein the body layers are adhered with a phenolic conductive adhesive. 2. The charging roller member according to claim 1, wherein the electrical resistance between the surface of the phenolic conductive adhesive and the conductive support shaft is 5 Ω or less. 3. The charging roller member according to claim 1, wherein the phenolic conductive adhesive layer has a thickness of 3 to 10 μm. 4. The method for manufacturing a charging roller member according to claim 1, wherein a phenolic conductive adhesive is applied to the outer periphery of the conductive support shaft and before the conductive support shaft is brought into contact with epichlorohydrin rubber. And a method of manufacturing a member for a charging roller, wherein preliminary heating is applied to the member.