JP2003149892A - Conductive rubber roller and transfer roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive rubber roller of a transfer roller, electrifying roller or developing roller or the like causing no sticking to a photoreceptor or having no contaminating property without performing special surface treatment such as irradiation with UV rays or coating with a resin. SOLUTION: In the conductive rubber roller having a rubber layer formed on a conductive core material, the rubber material of the rubber layer essentially comprises acrylonitrile butadiene rubber or epichlorohydrin rubber or a mixture of these and further, liquid polybutadiene is added to the material. The content of the liquid polybutadiene is <=20 mass% with respect to the main component of the rubber material, preferably 0.5 to 15 mass%, and more preferably 1 to 10 mass%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller used in an image forming apparatus such as an electrophotographic apparatus, a printer and an electrostatic recording apparatus, and further to an image bearing member such as a photoconductor, an electrophotographic process and an electrostatic roller. The present invention relates to a transfer roller of a transfer device for transferring a transferable image by a toner image formed and carried by an image forming means such as a recording process onto a recording medium such as paper or a transfer material.

[0002]

2. Description of the Related Art Conventionally, most of electrophotographic image forming apparatuses employ a contact transfer system which produces very little harmful ozone. The excellent roller transfer method is mainly used.

In the roller transfer system, a transfer roller having an elastic rubber roller layer is pressed against a photosensitive drum, which is an image carrier, to form a transfer nip, and a recording material is conveyed to the transfer nip while being applied to the transfer roller. The toner image on the photosensitive drum is transferred onto the recording material by the action of the transfer bias.

The transfer roller is generally a conductive sponge elastic layer having a resistance of 1 × 10 ⁶ to 1 × 10 ¹⁰ [Ω] on a core metal such as SUS or Fe made of carbon, an ion conductive filler or the like. Formed hardness 20-40 degrees (ASKER
-The elastic sponge roller of C) is used. Further, in recent years, as the market demand for printing on various recording materials has increased, an image forming apparatus using a solid transfer roller having a conductive solid rubber having an excellent transportability as an elastic layer has been developed.

Since the elastic layer of the solid transfer roller is a solid rubber having a high restoring force, the recording material holding force at the transfer nip portion is higher than that of a conventional sponge type transfer roller, and the solid transfer roller is fed. The back tension, postcard, cardboard, etc. are less affected by the conveyance resistance caused by rubbing on the recording material conveying path, and the recording material can be conveyed more stably.

Regarding the transfer roller, charging roller or developing roller used in an electrophotographic image forming apparatus such as a copying machine or a printer, conventionally, these rollers are attached to a photosensitive member, a belt, or the like, and There was a problem of contamination due to bleeding of fluid components. As a method for the purpose of preventing sticking or preventing contamination, a method of modifying the rubber on the surface by irradiating ultraviolet rays, or a method of coating a urethane resin having a conductive filler dispersed therein has been used. However, neither was satisfactory.

[0007] For example, in the ultraviolet irradiation method, it is difficult to set conditions such as irradiation dose and wavelength, and when irradiated strongly, an unexpected functional group is generated, conversely the adhesion with the photoconductor or the like is increased, or dust is removed. It promotes the adherence of such substances and may cause a contamination problem.

Further, in the coating of the above-mentioned filler-dispersed paint, it is difficult to solve problems such as coating unevenness and charging unevenness due to the non-uniform dispersion of the acting filler.
It was not an adequate solution to the problem.

[0009]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a conductive rubber roller used as a transfer roller, a charging roller, a developing roller, or the like can be formed without special surface treatment such as ultraviolet irradiation or coating with resin.
An object of the present invention is to provide a conductive rubber roller which is free from sticking to a photoreceptor and has no contamination.

[0010]

In order to solve the above problems, in the present invention, in a conductive rubber roller in which a rubber layer is formed on a conductive core material, the rubber material of the rubber layer is acrylonitrile butadiene rubber or The inventors have invented a conductive rubber roller containing epichlorohydrin rubber or a mixture thereof as a main component and further containing liquid polybutadiene.

Further, the content of the liquid polybutadiene is 20% by mass or less based on the main component of the rubber material, so that the conductive rubber roller is further excellent.

In the present invention, by utilizing such a conductive roller as a transfer roller, the usefulness in this application is increased.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

FIG. 2 shows an example in which the conductive roller according to the present invention is used in an image forming apparatus. The image forming apparatus shown in the figure is an electrophotographic laser printer using a process cartridge, and the figure is a longitudinal sectional view showing the schematic configuration thereof. Further, the image forming apparatus shown in FIG.
A transfer device having a transfer roller is mounted.

The image forming apparatus shown in FIG. 1 includes a drum type electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") 1 as an image bearing member. The photosensitive drum 1 includes an organic photoconductor (OP) on the outer peripheral surface of a grounded cylindrical aluminum substrate.
The photosensitive layer of C) is provided. This photosensitive drum 1 is driven by a driving unit (not shown) in a direction of an arrow R1 to a predetermined process speed (peripheral speed), for example, 50 mm / s.
It is rotationally driven by ec.

The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 as a contact charging member. The charging roller 2 is disposed in contact with the surface of the photosensitive drum 1 and is driven to rotate in the arrow R2 direction as the photosensitive drum 1 rotates in the arrow R1 direction. An oscillating voltage (AC voltage V _AC + DC voltage V _DC ) is applied to the charging roller 2 by a charging bias application power supply (high voltage power supply), whereby the surface of the photosensitive drum 1 becomes −600 V (dark part potential V _d ). It is uniformly charged. The surface of the photosensitive drum 1 after being charged is scanned and exposed by a laser beam output from a laser scanner and reflected by a mirror, that is, a laser beam modulated corresponding to a time-series electric digital image signal of target image information. Receive. As a result, on the surface of the photosensitive drum 1, an electrostatic latent image (bright portion Vl = -150V) corresponding to the target image information is obtained.
Is formed.

The electrostatic latent image is subjected to reversal development as a toner image by attaching the negatively charged toner 5 by the developing bias applied to the developing sleeve of the developing device 4.

On the other hand, a transfer material P such as paper fed from a paper feeding portion (not shown) is guided by a transfer guide 7 and transferred between the photosensitive drum 1 and the transfer roller 6 (transfer nip portion). ) T at the same timing as the toner image on the photosensitive drum 1. The transfer material P supplied to the transfer portion T is transferred onto the surface of the photosensitive drum 1 by the transfer bias applied to the transfer roller 6 by the transfer bias applying power source.
The upper toner image is transferred. At this time, the toner (residual toner) remaining on the surface of the photosensitive drum 1 without being transferred to the transfer material P is removed by the cleaning blade 9 of the cleaning device 8.

The transfer material P that has passed through the transfer portion T is separated from the photosensitive drum 1 and is introduced into the fixing device 10, where it is subjected to a fixing process of a toner image, and the main body of the image forming device (print) is formed as an image formed product (print). (Not shown) is discharged to the outside.

[0020]

EXAMPLE A conductive roller (FIG. 1) demonstrating the present invention was prepared as follows.

[Conductive roller] The rubber composition is one of acrylonitrile butadiene rubber and epichlorohydrin rubber as a rubber main component, or a mixture of both.
A predetermined amount of liquid polybutadiene is mixed with this. In addition, a vulcanizing agent such as sulfur, a sulfide-based vulcanization accelerator, a conductive material such as carbon black, and other auxiliaries are mixed.

The rubber composition is extruded using an extruder (not shown) to obtain an unvulcanized tubular conductive rubber molding, and then vulcanized at 160 ° C. for 30 minutes in a vulcanizing can. A tube-shaped conductive rubber molding is made, and then φ4-10m
The m conductive core material (core 61) was pressed into the inner diameter of the tube-shaped conductive rubber molded product (elastic layer 62) to obtain a roller-shaped molded body. This molded body was set on a polishing machine (not shown) equipped with a polishing grindstone GC80, and was polished to have an outer diameter of 15 mm at a rotation speed of 2000 RPM and a feed rate of 500 m / min, and a conductive roller was produced. did.

The materials used in each Example and Comparative Example are as follows. Acrylonitrile butadiene rubber Nipol DN401L Epichlorohydrin rubber Zeklon 3106 manufactured by Nippon Zeon Co., Ltd. Vulcanizing agent sulfur manufactured by Nippon Zeon Co .; ; Product name Rheno
gran MBT-80 Bayer dibenzothiazyl disulfide; trade name Rhenog
ran MBTS-80 Tetraethyl thiuram disulfide manufactured by Bayer Ltd .; trade name Rhen
ogran TETD-75 Other materials manufactured by Bayer Co., Ltd. Liquid polybutadiene; Polyoil 110 Nippon Zeon Co., Ltd. calcium carbonate; Product name Super SS Maruo Calcium Co., Ltd. carbon; Product name Asahi 15 Asahi Carbon Co., Ltd. Zinc oxide manufactured by the same company; Trade name: Zinc Hua 2 type Hakusui Tech Co., Ltd. stearic acid; Trade name, manufactured by Lunack S Kao Co., Ltd. Also, the characteristics regarding roller electric resistance, sticking property, staining property, kneading property, etc. Was measured by the following method.

<Electrical resistance of roller> The roller resistance is measured by contacting the shaft of the conductive roller with the shaft of the conductive roller in a state of being pressed to an aluminum drum having an outer diameter of 30 mm so that a total pressure of 9.81 N (1 kg) is applied. A voltage of 2 KV is applied between the aluminum drum and L / L (15 ° C x 10% RH), N / N (2
It was measured under each environment of 3 ° C. × 55% RH) and H / H (35 ° C. × 85% RH).

However, in the present invention, a sample is prepared so that the required electric resistance value of the roller for each application in the laser printer to be used is adjusted, and the sticking property and the contamination property of these are evaluated. Therefore, the resistance value is not shown because it is in a desired numerical range.

<Photoreceptor Sticking Property> φ15, Length 250
The conductive roller that has been molded and polished to a thickness of mm is brought into contact with a photoconductor used for a laser printer (Laserjet 4000N HP), and a load of 1000 g is applied to both ends.
It was left for 1 month in an environment of 40 ° C. and 95% RH. After leaving it for a while, the load was removed, and what was not adhered to the photosensitive member was designated as A, those which were adhered but disengaged from the photosensitive member due to the roller's own weight were designated as B, and those which were not separated due to the roller's own weight were designated as C. (Evaluation device diagram is not shown) <Photoreceptor Contamination> The photoreceptor evaluated for stickiness was incorporated into the cartridge of the laser printer, 30 sheets were printed in solid black, and there were no white lines of contact marks on the image. The product was designated as A, the product having white streaks at the beginning but disappearing in the middle was designated as B, and the product showing white streaks until the end was designated as C.

<Kneading workability> When kneading with a closed kneading machine such as a Banbury or a kneader, A has good kneading property, B has poor cohesion, and C has no cohesion. .

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

As the main rubber material of the roller of the present invention,
Acrylonitrile butadiene rubber was 75 mass% and epichlorohydrin rubber was 25 mass%, and liquid polybutadiene was added in an amount of 0.5 to 10 mass% to Examples 1 to 5.

In addition, 1 acrylonitrile butadiene rubber
A series of 00% by mass, 50% by mass, 25% by mass, and 0% by mass (the remaining amount of the main component is epichlorohydrin rubber) is set as Examples 6 to 9, respectively, and liquid polybutadiene is added to the main component. Therefore, the content of 5% by mass proves that the effect of the present invention is guaranteed by the liquid polybutadiene regardless of the ratio of the main component rubber.

Other ingredients are listed in the table.

In addition, as a comparative example, a case was proved in which the presence of liquid polybutadiene is indispensable, and a problem occurs even if the amount of the liquid polybutadiene is too large.

The compounding ratios of the rubber compositions used in Examples and Comparative Examples are shown in Tables 1 and 2.

The raw materials shown in Tables 1 and 2 were kneaded with a mixer and an open roll to prepare rubber compositions of Examples and Comparative Examples.

The evaluation results of each roll are shown in Tables 3-4.

In the present invention, a conductive roller (transfer roller)
The roller resistance value of is within the numerical range required for the application, as a matter of course, the resistance value of the roller of the examples and comparative examples is not specified, but it is required for the specific application in the specific device. It goes without saying that the roller resistance value range is adjusted.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

According to the present invention, the main component of the rubber material is
It is an object of the present invention if any one of acrylonitrile butadiene rubber and epichlorohydrin rubber is mixed or mixed, and liquid butadiene rubber is blended in a predetermined amount thereof. There is no sticking to the photoconductor or the like, and the problem of contamination is solved.

Therefore, for example, when used as a transfer roller, there is no generation of streak-like or cloud-like images due to the sticking phenomenon, and no bleeding material is used. Since there is no contamination,
There are no abnormal images such as black dots. Further, it is possible to form a good image without causing a cost increase due to a post-process such as an ultraviolet treatment and without causing a problem due to an insufficient or excessive amount of ultraviolet irradiation.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a transfer roller according to the present invention.

FIG. 2 is an overall sectional view of an image forming apparatus according to the present invention.

[Explanation of symbols]

1 ... Photosensitive drum 2 ... Charging roller / charging device 3 ... Scanning exposure / exposure means 4 developing device 5 ... Toner 6 ... Transfer roller 7 ... Transfer guide 8 ... Cleaning device 9 ... Cleaning blade 10: Fixing device 61 ... Core metal 62 ... Elastic layer T: Transfer section P ... Transfer material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hironori Ohashi             1888-2 Kukizaki, Kukizaki-cho, Inashiki-gun, Ibaraki Prefecture             Within Kasei Co., Ltd. F-term (reference) 2H071 BA43 DA09                 2H200 GA23 HA01 HB12 HB22 JA01                       JA25 JA26 JA27 MA03 MA11                       MA17 MA20 MB01 MC01                 3J103 AA02 AA13 BA41 FA07 FA15                       GA02 GA57 GA58 GA74 HA03                       HA12 HA20 HA53

Claims (5)

[Claims] 1. A conductive rubber roller having a rubber layer formed on a conductive core material, wherein the rubber material of the rubber layer is mainly composed of acrylonitrile butadiene rubber, epichlorohydrin rubber or a mixture thereof, and liquid polybutadiene is further added. Conductive rubber roller characterized by being 2. The conductive rubber roller according to claim 1, wherein the content of the liquid polybutadiene is 20% by mass or less based on the main component of the rubber material. 3. The conductive rubber roller according to claim 1, wherein the content of the liquid polybutadiene is 0.5 to 15 mass% with respect to the main component of the rubber material. 4. The conductive rubber roller according to claim 1, wherein the content of the liquid polybutadiene is 1 to 10 mass% with respect to the main component of the rubber material. 5. A transfer roller used in contact with an image bearing member of an electrophotographic apparatus, wherein the transfer roller is a transfer roller.
5. A transfer roller, which is the conductive rubber roller according to any one of items 1 to 4.