JP2003120658A - Conductive roller and transfer roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roller and a transfer roller causing no pollution to an electrophotographic photoreceptor, causing no sticking to the electrophotographic photoreceptor without performing special surface treatment such as ultraviolet ray irradiation, and having reduced influence on compressive permanent set performance. SOLUTION: This conductive roller forms a rubber layer on a conductive core member. The conductive roller and the transfer roller using the conductive roller are characterized by composing a rubber material of the rubber layer out of a polymer mainly composed of acrylonitrile butadiene rubber, and including a substitute including no sulfur and chlorine by 20 mass part or more to 100 mass part of the acrylonitrile butadiene rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller and a transfer roller, and more particularly to a conductive roller used in an electrophotographic copying machine, an electrostatic recording device and the like, and a transfer roller used for the conductive roller.

[0002]

2. Description of the Related Art In an electrophotographic copying machine, an electrostatic recording device, etc., a toner, which is a developer, is attached to an electrostatic latent image obtained by exposing a uniformly charged electrophotographic photosensitive member, and the toner is removed. An image is formed by transferring to a transfer medium such as paper. The electrophotographic photosensitive member may be charged by a non-contact charging method using corona discharge or a contact charging method using a semiconductive roller. Similarly, the transfer method includes a non-contact corona transfer method and a roller method.

The conductive roller has a volume resistivity of 1
A conductive rubber material having an electric resistance of × 10 ⁵ to 1 × 10 ¹¹ Ω · cm is used. The conductive rubber material is mixed with a conductive filler such as carbon black in order to achieve the desired conductivity. However, since the electric resistance of the conductive rubber material thus obtained depends on the change in applied voltage, an applied voltage control device is required when used as a charging member. Further, the resistance value varies depending on the dispersion state of the conductive filler in the rubber material, and it is difficult to obtain a rubber material having stable resistance.

As a means for solving the above problems, there is known a method of obtaining a predetermined electric resistance by using a polymer having a low volume resistivity as a rubber component used as a charging member. Although such a conductive rubber has resistance changes due to environments such as low temperature and low humidity and high temperature and high humidity, it does not rely on conductive fillers such as carbon black, so that resistance values vary depending on the material lot and dependence on the applied voltage. The material is small and extremely easy to handle. The conductive polymer includes acrylonitrile butadiene rubber, epichlorohydrin rubber, urethane rubber and the like. Among them, acrylonitrile butadiene rubber has good processability, is relatively inexpensive and easy to handle, and thus is used as a material for the conductive roller. .

However, the above-mentioned electroconductive polymer is tacky, and when used in the electroconductive roller, the one used in contact with the electrophotographic photoreceptor has a problem of sticking to the electrophotographic photoreceptor. Become. The sticking of the conductive roller to the electrophotographic photosensitive member hinders the rotation of the electrophotographic photosensitive member when the recording apparatus such as an electrophotographic copying machine is restarted after a certain period of rest. Conventionally, in order to prevent sticking to the electrophotographic photosensitive member, the conductive roller is subjected to surface treatment such as ultraviolet irradiation or ozone exposure (Japanese Patent Laid-Open No. 8-292).
640 publication). However, although such a method has the effect of preventing sticking, not only the number of steps is increased but also the processing equipment is expensive, which leads to an increase in cost.

Further, the conductive roller, especially the charging roller, must maintain a uniform nip width in order to uniformly charge the electrophotographic photosensitive member, and the transfer roller has a problem of paper transportability. However, a plasticizer usually used for the above conductive polymer cannot be used because of problems such as contamination of the electrophotographic photosensitive member and cracking. Paraffin-based process oil is said to have less contamination on electrophotographic photoreceptors,
It cannot be used because it lacks compatibility with the conductive polymer and bleeds out. Therefore, liquid polymers such as liquid acrylonitrile butadiene rubber have been added for the purpose of reducing the hardness without contamination.
This method also lowers the hardness but increases the stickiness of the rubber, and the sticking to the electrophotographic photosensitive member becomes large. Further, a polymer having a low viscosity that does not participate in crosslinking, such as a liquid polymer, deteriorates the compression set when added to rubber. Since the roller is in contact with the electrophotographic photosensitive member under a constant load, if the compression set is deteriorated, the charging roller cannot uniformly charge the electrophotographic photosensitive member, and the transfer roller is a sheet of paper. It is not preferable because the transportability is poor.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by a conductive roller, that is, while keeping the compression set, there is no contamination on the electrophotographic photoreceptor,
Another object of the present invention is to provide a conductive roller that does not stick to an electrophotographic photosensitive member without performing a special surface treatment such as ultraviolet irradiation.

Another object of the present invention is to provide a transfer roller using the above conductive roller.

[0009]

According to the present invention, in a conductive roller in which a rubber layer is formed on a conductive core member, the rubber material of the rubber layer is a polymer containing acrylonitrile butadiene rubber as a main component. Also provided is a conductive roller comprising 100 parts by mass of acrylonitrile butadiene rubber and 20 parts by mass or more of a sub containing no sulfur and chlorine.

According to the present invention, in a transfer roller arranged opposite to an electrophotographic photosensitive member in an image forming apparatus for developing an electrostatic charge image on the electrophotographic photosensitive member with a developer, the transfer roller has the above-mentioned conductive property. A transfer roller is provided which is a flexible roller.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The semiconductive rubber material used in the present invention will be described in detail below.

The rubber component used in the present invention is an acrylonitrile butadiene rubber or a blend polymer of an acrylonitrile butadiene rubber and a synthetic rubber. The acrylonitrile butadiene rubber used in the present invention is not particularly limited, but the acrylonitrile content is preferably 35% by mass or less, more preferably 20% by mass or less. When the acrylonitrile content is 20% by mass or less, the resistance change due to low temperature and low humidity to high temperature and high humidity is reduced. Synthetic rubbers to be blended with acrylonitrile butadiene rubber also include, but are not limited to, epichlorohydrin rubber, acrylic rubber, urethane rubber, ethylene propylene rubber and styrene butadiene rubber. Among them, epichlorohydrin rubber has excellent compatibility with acrylonitrile butadiene rubber,
When both polymers are blended, they are evenly dispersed. Also,
The epichlorohydrin rubber copolymerized with ethylene oxide has a lower resistance than acrylonitrile butadiene rubber, and the resistance can be adjusted by blending it, and therefore it is suitable for blending with acrylonitrile butadiene rubber.

The sub added in the present invention is a sub containing no sulfur and chlorine. When sub is added to acrylonitrile butadiene rubber, in addition to being used as a softening agent, it is intended to be used as a processing aid such as extrudability of unvulcanized rubber and prevention of bleed-out of plasticizer. Is a black sub. However, when a sub containing sulfur such as black sub is used, the compression set decreases. Sub is generally a fat or oil cross-linked with sulfur or sulfur chloride, and sulfur is present between the cross-links.
When this sub-substance is added, the compression set lowers, but it is considered that the progress of new cross-linking and the like due to the inclusion of sulfur. However, the sub which does not contain sulfur and chlorine shows a very small reduction in compression set even when a large amount is blended. It is considered that the sub containing no sulfur and chlorine does not have sulfur as in the above sub, and the fats and oils are directly cross-linked.

In the present invention, the amount of the sub blended is essential to be 20 parts by mass or more, and preferably 30 to 10 parts by mass based on 100 parts by mass of acrylonitrile butadiene rubber.
It is 0 part by mass. When the amount of sub is less than 20 parts by mass, sticking to the electrophotographic photosensitive member occurs, and when it exceeds 100 parts by mass, kneading processability is likely to decrease, and the addition amount in the above range is preferable.

The conductive rubber material in the present invention is obtained by kneading and dispersing an additive in the above-exemplified rubber and crosslinking it. As the above additives, a vulcanizing agent, a vulcanization accelerator, a filler, a conductive agent, when used as a foam,
Conventionally known foaming agents, foaming aids and the like can be used.

As the vulcanizing agent used in the present invention, conventionally known crosslinking agents can be used in addition to sulfur or organic sulfur compounds. As the vulcanizing chemicals, thiazoles such as mercaptobenzothiazole, vulcanization accelerators such as tetramethylthiuram disulfide, and vulcanization accelerator aids such as zinc oxide are used. The compounding amount is 100 parts by mass of the rubber component,
0.1 to 10 parts by mass is preferable, and 1 to 5 parts by mass is particularly preferable. As the vulcanization method, known methods such as steam can vulcanization and press vulcanization can be used.

Examples of the filler include heavy calcium carbonate, light calcium carbonate, clay and the like. Examples of the reinforcing agent include carbon black and silica. The rubber material according to the present invention is obtained by blending the above-exemplified components, kneading, heating at 160 to 180 ° C. for 10 to 40 minutes, and vulcanization. Further, the conductive roller of the present invention is generally manufactured by extrusion molding into a cylindrical shape, vulcanizing by steam vulcanization, and then press-fitting and grinding a core member,
It is used after being molded into a desired shape and ground by a conventionally known method such as press molding using a mold. Further, after grinding, a resin layer can be provided on the rubber layer by dipping or the like.

[0018]

The present invention will be described below with reference to more specific constitutions, but the scope is not limited to the exemplified ones.

Preparation of rubber materials and test pieces (Examples 1 to 12 and Comparative Examples 1 to 5) For each Example and Comparative Example, the following materials were used as NBR (AN content 15% by mass): N260S (JSR Corporation). NBR (AN content 18% by mass): Nipol DN401L (ZEON Corporation) NBR (AN content 22% by mass): Nipol DN407 (ZEON Corporation) NBR (AN content 33.5% by mass): Nipol 1052J (ZEON Corporation) Co., Ltd.) Epichlorohydrin rubber: Gechron3106 (Zeon Corporation) BR: UBEPOLE230 (Ube Industries, Ltd.) EPDM: EPT4045 (Mitsui Chemicals, Inc.) Sulfur-free sub: Rhenopren EPS (Bayer Co., Ltd.) Black sub: Black sub pure species ( Tenma Sub Chemical Co., Ltd.) Calcium carbonate: Super SS (Maruo Calcium Co., Ltd.) Zinc oxide: Zinc oxide 2 types (Haxui Tech Co., Ltd.) Stearin Acid: Stearic acid S (Kao Corporation) MBT: Nox Cellar M (Ouchi Shinko Chemical Co., Ltd.) TETD: Nox Cellar TET (Ouchi Shinko Chemical Co., Ltd.) Sulfur: Salfax 200S (Tsurumi Chemical Co., Ltd.)

Mix as shown in Tables 1 and 2 and knead,
The rubber material was charged into a mold and vulcanized by heating at 160 ° C. for 30 minutes to prepare a block having a diameter of 29 mm and a thickness of 12.5 mm and a sheet having a 12 mm square and a thickness of 2 mm.

<Evaluation of Adhesiveness> In each of the examples and comparative examples, the material was extruded into a cylindrical shape and steam-vulcanized at 160 ° C. for 30 minutes. A roller ground to a diameter of 15 mm and a length of 250 mm is brought into contact with the electrophotographic photosensitive member of the cartridge used in the laser printer Laserjet 4000N made by Hewlett Packard, a load of 1000 g is applied to both ends, and an environment of 40 ° C / 95% RH is set. I left it down for a month. After leaving it for a while, remove the load, and those that did not stick to the electrophotographic photosensitive member were evaluated as ○, those that were adhered but disengaged from the electrophotographic photosensitive member due to the roller's own weight were marked as △, and those that did not disengage from the electrophotographic photosensitive member even with the roller's own weight. Is indicated by x. As a roller, a rating of Δ or higher is required. The results are shown in Table 3.

<Evaluation of compression set> For each example and comparative example, JIS-K was conducted at 70 ° C. for 72 hours at 25% compression.
The compression set was measured according to 6262. The results are shown in Table 3.
Shown in.

<Evaluation of volume resistivity> 1 kV on a 2 mm sheet
Voltage is applied, L / L (15 ° C / 10% RH), N / L
N (23 ° C / 55% RH) and H / H (35 ° C / 85%)
The volume resistivity was measured under each environment (RH). The results are shown in Table 3.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

From Examples 1 to 3 and Comparative Examples 1 and 2, it is understood that the addition amount of the sub is 20 parts by mass or more. If the amount is less than 20 parts by mass, the sticking property will be poor and the roller will stick to the electrophotographic photosensitive member.

From Examples 1 to 3 and Comparative Examples 3 to 5, it is understood that the sub is preferably one containing no sulfur and chlorine. The use of a sub containing sulfur is not preferable because the compression set decreases.

From Examples 1 to 6, it is understood that the acrylonitrile content of NBR is more preferably 20% by mass or less.
If the amount exceeds 20% by mass, the order of variation due to the environment becomes large.

From Example 1 and Examples 7 to 12, it can be seen that epichlorohydrin rubber is preferable as the polymer to be blended. When ethylene propylene rubber (EPDM) or butadiene rubber (BR) is used, the resistance is slightly increased, whereas when epichlorohydrin rubber is used, the resistance is greatly decreased. As a result, the resistance adjustment range is widened and the resistance can be adjusted to an appropriate value.

[0031]

As described above, according to the present invention, there is no sticking to the electrophotographic photosensitive member without any special surface treatment such as contamination of the electrophotographic photosensitive member or irradiation of ultraviolet rays, and compression set property. It has become possible to provide a conductive roller that has little influence on

Therefore, the conductive roller of the present invention is suitable for use as a conductive roller in an electrophotographic copying machine or the like, especially as a transfer roller.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/02 101 G03G 15/02 101 15/16 103 15/16 103 (72) Inventor Daisuke Ohno Ibaraki Ibaraki 1888-2 Kizaki, Inashiki-gun, Inashiki-gun, F-term, Canon Chemical Co., Ltd. (reference) 2H071 BA43 DA09 2H200 FA02 FA08 FA16 GB50 HA02 HB12 HB22 JA02 JA23 JA25 JA26 JA27 JB10 LC02 LC03 LC09 MA03 MA04 MA08 MA13 MA14 MA17 MB01 MB04 MC01 3J103 AA02 BA41 FA07 GA02 GA57 GA58 GA60 GA74 HA12 HA20 HA53 4J002 AC071 AC083 AE012 BB153 BG043 CH043 CK023 FD010 FD022 FD140 FD150 GQ02

Claims (4)

[Claims] 1. A conductive roller having a rubber layer formed on a conductive core member, wherein the rubber material of the rubber layer is:
Acrylonitrile butadiene rubber comprising a polymer containing acrylonitrile butadiene rubber as a main component, and 1
A conductive roller comprising 20 parts by mass or more of a sub that does not contain sulfur and chlorine with respect to 00 parts by mass. 2. The electrically conductive roller according to claim 1, wherein the acrylonitrile content of the acrylonitrile butadiene rubber in the polymer is 20% by mass or less. 3. The conductive roller according to claim 1, wherein the polymer other than acrylonitrile butadiene rubber contained in the polymer is epichlorohydrin rubber. 4. A transfer roller which is arranged facing an electrophotographic photosensitive member in an image forming apparatus for developing an electrostatic image on an electrophotographic photosensitive member with a developer, the transfer roller according to any one of claims 1 to 3. A transfer roller, which is the conductive roller according to any one of claims 1 to 3.