JPH07238923A - Conductive rubber roller and manufacture thereof - Google Patents

Abstract

PURPOSE:To easily form smooth surface having high accuracy by constituting at least the inner side layer out of double rubber layers by a foam rubber layer and constituting the outer side layer by a non foam rubber layer. CONSTITUTION:A conductive rubber roller consists of a shaft 1 and a rubber layer 2 having conductive property, the rubber layer 2 is formed of at least double layers, the double layers is pushed out simultaneously, integratedly, continuously, and in a hollow shape by a plurality of extruding machines, the shaft 1 is inserted after curing. Thermal plastic rubber such as nitrile butadiene rubber, chloroprene, or the like is used as rubber component having non foaming of an outer side layer 2b, and component formed by blending ethylene propylene rubber and foaming body of copolymerization rubber of epichlorohydrine and ethylene oxide is used as the foaming conductive rubber of an inner side layer 2a. Short fiber and the like such as carbon black, metal oxide, and the like are used as a blending conductive material. The outer side layer 2b is polished so as to obtain smooth surface having high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roll for applying an electric potential of a predetermined polarity to an object to be charged such as a photosensitive drum or a recording medium in an electrophotographic recording apparatus or the like, and a method for producing the same. The present invention relates to a conductive roll capable of meeting various required characteristics and having a simplified process, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Copiers and laser beam printers
An electrophotographic recording device widely used for example is generally provided with a drum-shaped photoconductor (hereinafter referred to as a photoconductor drum), and the photoconductor drum is charged and exposed to form an electrostatic latent image. After that, the toner is transferred according to the latent image on the photosensitive drum.
The toner on the photosensitive drum is transferred to a recording medium such as recording paper to transfer the toner, and then the toner on the photosensitive drum is discharged to a predetermined potential and the toner remaining on the photosensitive drum. To prepare for recording. Further, the toner carried on the recording medium by the transfer is fixed to the recording medium by melting and pressure bonding,
This completes a series of recording operations.

A charging roller for applying a predetermined potential to a charging area of the photosensitive drum of the electrophotographic recording apparatus, a developing roller for conveying the toner to the photosensitive drum,
A transfer roll that gives a predetermined potential to the recording medium conveyed to the transfer region, or a conductive roll such as a charge eliminating roll that makes the charged region of the photosensitive drum after transfer uniform to a constant potential. Is a base made of at least a conductive shaft and a rubber having good conductivity provided around the shaft.
In some cases, the base layer is formed of a base layer or a conductive film layer for covering the base layer for adjusting the electric resistance of the roll and preventing contamination of the photosensitive drum and the recording medium.

Such a conductive rubber roll has a balance of the above-mentioned uses, parts, and various required characteristics,
For example, it is often required to maintain stable conductive performance and at the same time have rubber elasticity having excellent compression characteristics.
Moreover, since the individual required characteristic values are infinite, the number of cases in which at least the rubber layer as described above is difficult to deal with in the conventional case increases when it is attempted to obtain products corresponding to each. There is.

On the other hand, such a roll for an OA equipment, for example, is also manufactured by combining complicated steps, so that the above-mentioned multi-product small-quantity production cannot be avoided. There is a problem that cost reduction is very difficult.

[0006]

The basis of the present invention has been made in view of the above circumstances, and uses a conductive rubber roll having a structure capable of imparting more functionality to a rubber layer. As a result, the conductive rubber roll and its production are widened in choices to meet various required characteristics, and further, the production process of the roll can be simplified as much as possible and the production cost of the rubber roll can be reduced. It is intended to provide a method. A further object of the present invention is to relatively easily obtain a conductive rubber roll having a highly precise and smooth surface.

[0007]

In order to achieve the above object, the constitution and manufacturing method of the conductive rubber roll of the present invention are as follows. A conductive rubber roller comprising a shaft and a conductive rubber layer provided on the outer periphery of the shaft as claimed in claim 1, wherein the rubber layer comprises at least two layers. -It is mandatory that the structure is La. Here, the two layers include both non-foamed rubber, both layers of foamed rubber, or both of non-foamed rubber and foamed rubber. As shown, the inner layer (shaft side) of the two rubber layers is a foamed rubber layer, and the outer layer (used surface side) is a non-foamed rubber layer, which is a conductive rubber roller structure.

Further, according to a second aspect of the present invention, in the rubber roller, the rubber layer is hollow (tube-shaped), and a shaft is inserted later to form a conductive rubber roller. The conductive rubber roller is characterized in that the inner diameter of the hollow portion of the rubber layer is sufficiently smaller than the diameter of the shaft to be inserted. At this time, the inner diameter of the hollow rubber layer is preferably about 0.50 to 0.95 of the diameter of the shaft. If the inner diameter of the hollow portion of the rubber layer is too small, it becomes difficult to insert the shaft. On the contrary, if it is too large, the binding force with the shaft is lost.

Further, as a method for producing the conductive rubber roller of the present invention, as described in claim 3, a conductive rubber roller comprising a shaft and a rubber layer having conductivity provided on the outer periphery of the shaft. -A conductive rubber roller in which the rubber layer is composed of at least two layers, and the two layers are extruded simultaneously and integrally into a hollow shape (tube shape) by a plurality of extruders. The method for producing a conductive rubber roller is characterized in that the shaft is inserted after being vulcanized.

Here, as the material of the rubber having conductivity which constitutes the rubber layer, a non-foamed or foamed rubber composition containing a conductive material can be used.

As the rubber component constituting the non-foamed conductive rubber composition, nitrile butadiene rubber, chloroprene rubber, isoprene rubber, styrene butadiene rubber, ethylene propylene rubber, isoprene rubber, polynorbornene rubber, etc. are used as usual rubber or styrene. A thermoplastic rubber such as butadiene styrene rubber (SBS) or its water additive (SEBS) can be used, and is not particularly limited. Of course, rubber which does not impart conductivity may be used depending on the case.

Further, the foamed conductive rubber is not particularly limited, but ethylene propylene rubber, chloroprene rubber, chlorosulfonated polyethylene rubber and the like mixed with a conductive material, epichlorohydrin and ethylene oxide copolymerization A foam of rubber or a foam of a copolymer rubber of epichlorohydrin and ethylene oxide mixed with a conductive material can be preferably used.

As the conductive material to be added to these rubber compositions, carbon black, graphite, metal, conductive powders of conductive metal oxides (tin oxide, titanium oxide, etc.) and carbon fibers, Various conductive fibers such as metal oxide short fibers can be used.

As the conductive rubber roller preferable in the present invention, the resistance value of the entire roller is 10 ³ to 10 ⁷ Ω, and the volume resistivity value of the rubber layer is 10 ¹ to 10 ¹³ Ωcm, preferably 10 ³ It is desirable that the hardness of the roller is between 10 ¹² Ωcm and the inner layer (non-foamed rubber layer) of the two layers has JIS-A hardness.
The hardness is preferably 20 ^{0 to} 60 ^0, preferably 30 ⁰ to 50 ⁰ , and the outer layer (foamed rubber layer) has Aska-C of 20 ⁰ to 70 ^0, preferably 30 ^{0 to} 60 ⁰ . Also, the above inner layer,
The outer layer preferably has a thickness of 1 to 50 mm, preferably 2 to 10 mm, and an outer layer of 0.1 to 3 mm, preferably 0.5 to 2 mm.

In the conductive roller of the present invention, it is possible to coat a single layer or a plurality of conductive layers on the base layer in order to adjust the electric resistance of the roller and prevent contamination of the photosensitive drum and the recording medium. However, the conductive layer preferably used in this case has a temperature of 25 ° C. and a relative humidity of 50% RH.
Volume resistance value at 1.0 × 10 ^{6 to} 1.0 × 10 ¹³
A conductive adhesive layer having a volume resistance value of 1.0 × 10 ¹³ Ω · cm or less at a temperature of 25 ° C. and a relative humidity of 50% RH is preferably used. Further, as a method of forming the conductive film, a method of integrally molding as a single layer or a plurality of layers using a plurality of extruders similar to the base layer or a method of extruding these films and expanding them with air to form a shrink tube. Examples of the method include a method of forming, covering the base layer and heat-treating it.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. (Example) An ethylene-propylene-diene terpolymer in which a blowing agent was mixed, using two extruders and using a die connected to each extruder as shown in FIG. 3 (b). (EPDM, inner layer) 2a and EPDM (outer layer) 2b containing no blowing agent were simultaneously extruded. This is vulcanized in a continuous vulcanization tank that uses both high frequency and hot air, and the inside diameter is 5 mm and the foamed rubber is 2.5 m thick inside.
As a result, a non-foamed rubber was obtained as a cylindrical (tube-shaped) vulcanized product having a thickness of 1 mm. A metal shaft of 6 mmΦ was inserted into this while air with a pressure of 1 kg applied was blown from the side opposite to the shaft insertion side to expand the inside of the hollow (Fig. 2), and a conductive rubber roll (Fig. 1) was obtained. . This was ground to an outer diameter of 12 mm with a cylindrical grinder. At this time, the accuracy of the outer diameter is 1
2 ± 0.09 mm, and the maximum runout was 0.10 mm or less. The ten-point average roughness Rz of the surface was 10 μ.

(Comparative Example) As a comparative example, EPDM mixed with a foaming agent was extruded from an ordinary rubber extruder and a die (Fig. 3 (a)) connected thereto, and the EPDM was extruded with a continuous vulcanization spear. This was vulcanized to obtain a cylindrical (tube-shaped) vulcanizate having an inner diameter of 5 mm, an inner foamed rubber having a thickness of 2.5 mm and an outer non-foamed rubber having a thickness of 1 mm. A 6 mmΦ metal shaft was inserted into this while the air was blown to expand the inner tube, and a conductive rubber roll was obtained. This was ground to an outer diameter of 12 mm with a cylindrical grinder. At this time, the accuracy of the outer diameter is 1
The deviation was 2 ± 0.13 mm and the maximum was 0.12 mm, but the ten-point average roughness Rz of the surface was 17 μ.

[0018]

As described above, the basic effect of the present invention is that in a conductive rubber roller composed of a shaft and a conductive rubber layer provided on the outer circumference of the shaft, the rubber layer is By requiring at least two layers, it has heretofore been difficult to meet many required properties when the rubber layer is a single layer, so to speak, with one rubber layer. However, by making this a plurality of layers, it is possible to allow each layer to share the required characteristics so that more characteristics can be satisfied.

In particular, of the two rubber layers, an inner layer (shaft side) is a foamed rubber layer, and an outer layer (used surface side) is a non-foamed rubber layer, which is a conductive rubber roller. By polishing the layer with a cylindrical grinder, etc., when the conventional surface is only the foamed rubber layer, the roller with a very high accuracy can be obtained.
It is possible to obtain a highly accurate and smooth surface, which is not obtained. That is, when the surface layer is only the foamed rubber layer, when it is polished as it is, the cells of the foamed product are exposed on the surface and the smoothness is lost, and further coating or film coating is applied to cover this. Even if it does, unevenness will be created on the surface.

Further, the effect of the present invention is that the plurality of rubber layers are extruded simultaneously and integrally in a hollow shape (tube shape) by a plurality of extruders in advance and vulcanized.
By cutting into an appropriate size and inserting the shaft into this to obtain a conductive rubber roll, the conventional manufacturing process can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a conductive roll of the present invention.

FIG. 2 is a schematic partial cross-sectional view showing an example (inserting a shaft into a hollow (tube-shaped) rubber vulcanizate) of the method for producing a conductive roll of the present invention.

FIG. 3 (b) is a schematic cross-sectional view showing a die of a two-layer rubber extruder used for producing the conductive roll of the present invention. FIG. 3A shows a die of a conventional single layer rubber extruder.

[Explanation of symbols]

 1: Shaft 2: Rubber layer 2a: Foamed rubber layer 2b: Non-foamed rubber layer 3: Extrusion die

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[Procedure amendment]

[Submission date] September 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a conductive roll of the present invention.

FIG. 2 is a schematic partial cross-sectional view showing an example of a method for producing a conductive roll of the present invention (inserting a shaft into a hollow (tube-shaped) rubber vulcanized product).

FIG. 3 (2) is a schematic cross-sectional view showing a die of a two-layer rubber extruder used for producing the conductive roll of the present invention. FIG. 3 (1) shows a die of a conventional single layer rubber extruder.

[Explanation of symbols] 1: Shaft 2: Rubber layer 2a: Foamed rubber layer 2b: Non-foamed rubber layer 3: Extrusion die

Claims (3)

[Claims] 1. A conductive rubber roller comprising a shaft and at least an electrically conductive rubber layer provided on the outer periphery of the shaft, wherein the rubber layer comprises at least two layers, and the two rubber layers. Of which, the inner layer (shaft side)
Is a foamed rubber layer, and the outer layer (used surface side) is a non-foamed rubber layer. 2. The conductive rubber roller according to claim 1, wherein in the rubber roller, the inner diameter of the hollow portion of the rubber layer is sufficiently smaller than the outer diameter of the shaft to be inserted.
La. 3. A conductive rubber roller comprising a shaft and at least an electrically conductive rubber layer provided on the outer periphery of the shaft, wherein the rubber layer is at least two conductive rubber rollers. The two layers are simultaneously and integrally extruded by a plurality of extruders into a hollow shape (tube shape), vulcanized, and then the shaft is inserted. 1. The method for producing a conductive rubber roller as described in 1 or 2.