JP2007155769A - Conductive rubber roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rubber roller excellent in ozone deterioration resistance and less liable to contaminate a photoreceptor. <P>SOLUTION: The conductive rubber roller has a conductive elastic layer comprising a conductive elastomer composition on a conductive support, wherein the conductive elastomer composition contains (a) 100 parts by mass of only acrylonitrile-butadiene rubber or acrylonitrile-butadiene rubber and epichlorohydrin rubber and (b) 5-40 parts by mass of epoxidized polybutadiene rubber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive rubber roller that can be used as a charging roller, a transfer roller, a developing roller and the like provided in an image forming apparatus using an electrophotographic process.

  Conventionally, in an electrophotographic apparatus of contact charging and contact transfer type, a conductive rubber roller having a form suitable for each application such as a charging roller, a transfer roller, and a developing roller is used. As shown in FIG. 1, a schematic cross-sectional view of a conductive rubber roller has a metal core 1 and a conductive elastic layer 2 on the outer periphery thereof. If necessary, resistance adjustment and dirt / bleed prevention are provided outside the conductive elastic layer 2. In many cases, the surface layer 3 is provided with a plurality of layers.

  In an electrophotographic apparatus, a charging roller performs uniform charging by contact with a photoconductor, and a developing roller uses a uniform nip to ensure functionality as a toner transport body that forms a uniform toner thin film. It is required to keep the width. For this reason, these conductive rubber rollers need to have adequate hardness and sufficient recovery against the compressive force caused by contact, and have a low hardness suitable for use in pressure contact to maintain the nip width. A roller is used. However, when a large amount of softener / plasticizer is added to reduce the hardness, if the same part is left in pressure contact for a long time, low molecular weight substances will bleed from the conductive elastic layer, causing photoconductor contamination. There are things to do.

Further, the conductive rubber roller used in the electrophotographic apparatus is often used by controlling the resistance value in a semiconductive region (a range of about 10 ⁵ to 10 ¹⁰ Ωcm). In general, conductive carbon black is added to obtain a resistance value in the semiconductive region, but it is difficult to stably obtain a desired resistance value. In addition, a relatively stable resistance value can be easily obtained by using an ionic conductive agent such as a quaternary ammonium salt. However, if a large amount of the ionic conductive agent is added, bleeding may occur and the contamination of the photoreceptor may become a problem.

  In some cases, epichlorohydrin rubber is used for the conductive elastic layer of the conductive rubber roller because the volume resistance is low and a stable resistance value is easily obtained. However, when the epichlorohydrin rubber is vulcanized at a high temperature, chlorine in the epichlorohydrin rubber may be cut to generate hydrogen chloride. This hydrogen chloride may break the bond between the polymer and the organic additive to generate a low molecular weight component, which may cause photoconductor contamination. For the purpose of supplementing hydrogen chloride, acid acceptors such as hydrotalcite, magnesium oxide, and calcium oxide and calcium carbonate may be added as a filler for the purpose of improving processability. However, the metal element contained therein reacts with hydrogen chloride to produce a metal halide, which may dissolve in water and adhere to the photoreceptor. Therefore, when epichlorohydrin rubber is used for the conductive elastic layer, measures such as limiting the use of these acid-accepting agents and fillers and providing a surface layer with a thick film thickness are taken. There are many cases.

  On the other hand, acrylonitrile butadiene rubber (NBR) may be used for the conductive elastic layer of the conductive rubber roller. Since acrylonitrile butadiene rubber does not have a halogen group (chlorine), there is no photoreceptor contamination caused by chlorine as described above. In addition, the glass transition temperature of acrylonitrile butadiene rubber is higher than that of epichlorohydrin rubber, and the crosslinkability of butadiene is good. Is expensive. However, since acrylonitrile butadiene rubber has a higher volume resistance than epichlorohydrin rubber, it is often necessary to add a large amount of a conductive agent in order to obtain a resistance value in the semiconductive region. As a result, the viscosity becomes high and the extrusion processability deteriorates, or the hardness becomes high and it becomes difficult to secure an appropriate nip. Even when a plasticizer or softener is used as a countermeasure, if it is added in a large amount, it may cause contamination of the photoreceptor. Furthermore, since acrylonitrile butadiene rubber has a double bond in the main chain, there is a problem in that the rubber is deteriorated due to ozone generated during ultraviolet irradiation or discharge, causing cracks or increasing resistance.

On the other hand, the technique of improving ozone degradation resistance is reported by blending the acrylonitrile butadiene rubber with the epichlorohydrin rubber which is excellent in ozone degradation resistance (patent documents 1-3).
Japanese Patent Laid-Open No. 2003-064224 JP 2004-211062 A JP 2004-263059 A

  However, when the surface layer is thinned to several microns or less, or when a filler such as calcium carbonate must be used to improve workability, higher bleed resistance is required. In such a case, the addition amount of epichlorohydrin rubber must be suppressed to 20% or less with respect to the acrylonitrile rubber, and since the acrylonitrile butadiene rubber is the main component, ozone deterioration becomes a problem again. In order to add a small amount of epichlorohydrin rubber to enhance the resistance to ozone deterioration, it is necessary to highly vulcanize the epichlorohydrin rubber. However, since acrylonitrile butadiene rubber having a double bond in the main chain is more easily vulcanized than epichlorohydrin rubber, there is an adverse effect that the selection of the vulcanization system is limited. Moreover, since the shape of the sea-island structure changes depending on the rubber blending method and affects ozone degradation, there is a problem that advanced management and limiting conditions are required in the manufacturing process, and productivity is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive rubber roller that is excellent in ozone resistance deterioration and has less contamination of the photoreceptor.

In order to achieve the above object, the invention according to the present application is as follows.
1. In a conductive rubber roller having a conductive elastic layer made of a conductive elastic composition on a conductive support, the conductive elastic composition comprises:
(A) Component: 100 parts by mass of acrylonitrile butadiene rubber alone, or acrylonitrile butadiene rubber and epichlorohydrin rubber,
(B) component: 5-40 mass parts of epoxidized polybutadiene rubber,
A conductive rubber roller comprising:
2. 2. The conductive rubber roller as described in 1 above, wherein the conductive elastic composition contains only acrylonitrile butadiene rubber as the component (a).
3. 2. The conductive rubber roller as described in 1 above, wherein the conductive elastic composition contains acrylonitrile butadiene rubber and epichlorohydrin rubber as the component (a).
4). 4. The conductive rubber roller as described in 3 above, wherein a mass ratio of the acrylonitrile butadiene rubber and the epichlorohydrin rubber is 95/5 to 30/70.
5. 5. The conductive rubber roller according to any one of 1 to 4, wherein the epoxidized polybutadiene rubber has a number average molecular weight of 500 to 10,000.
6). 6. The conductive rubber roller according to any one of 1 to 5, wherein the main chain structure of the epoxidized polybutadiene rubber is a 1,2-polybutadiene structure.

  According to the present invention, it is possible to provide a conductive rubber roller which is excellent in ozone resistance deterioration and has less contamination of the photoreceptor.

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

  The conductive rubber roller of the present invention has a conductive elastic layer made of a conductive elastic composition on a conductive support. The conductive rubber roller of the present invention is suitable for a charging roller, a transfer roller, a developing roller and the like provided in an electrophotographic apparatus.

  The conductive support is not particularly limited as long as it has conductivity and functions as a support for a conductive rubber roller. As the material, for example, SUS, iron, copper, stainless steel, brass, conductive plastic, conductive elastomer, and the like can be used. The shape of the conductive support may be a cylindrical shape having a hollow central portion in addition to the columnar shape. The outer diameter of the conductive support is usually in the range of 4.0 to 8.0 mm.

The thickness of the conductive elastic layer is usually in the range of 0.5 to 5.0 mm. As the conductive elastic body composition constituting the conductive elastic layer,
(A) Component: 100 parts by mass of acrylonitrile butadiene rubber alone, or acrylonitrile butadiene rubber and epichlorohydrin rubber,
(B) component: 5-40 mass parts of epoxidized polybutadiene rubber,
Containing.

  As component (a), acrylonitrile butadiene rubber is used. Since acrylonitrile butadiene rubber does not have a halogen group (chlorine), contamination of the photoreceptor due to chlorine can be suppressed. In addition, since the glass transition temperature of acrylonitrile butadiene rubber is high and the crosslinkability of butadiene is good, the molecular mobility of the rubber after vulcanization is low, so the effect of suppressing bleed of low molecular weight substances is high.

  The characteristics of acrylonitrile butadiene rubber depend on the copolymerization amount of acrylonitrile. The greater the amount of acrylonitrile, the lower the molecular mobility, so that the bleed resistance is improved, the crack growth rate of ozone is reduced, and the ozone degradation resistance is improved. However, if the amount of acrylonitrile becomes too high, the compatibility with the epoxidized polybutadiene rubber used as the component (b) and the epichlorohydrin rubber that may be used together as the component (a) is deteriorated, and the rubber elasticity in a cold environment is also reduced. It will decline. Therefore, a medium-high nitrile having an acrylonitrile amount of 31% or more and less than 36% is preferable.

  The acrylonitrile butadiene rubber preferably has a Mooney viscosity of 15 to 80 ML (1 + 4) 100 ° C.

  As the component (a), acrylonitrile butadiene rubber can be used alone, but epichlorohydrin rubber can also be used in combination. By using epichlorohydrin rubber in combination, ozone resistance can be improved. Compared to acrylonitrile butadiene rubber, epichlorohydrin rubber has an SP value close to that of epoxidized polybutadiene rubber and is more compatible with epoxidized polybutadiene rubber. Therefore, since epichlorohydrin rubber also acts as a plasticizer / dispersant, it is possible to form a sea-island structure relatively easily, and to improve the ozone degradation resistance. The hydrogen chloride generated from the epichlorohydrin rubber at the time of vulcanization is supplemented by the epoxy group of the epoxidized polybutadiene rubber, so that generation of a causative substance of bleed can be suppressed and the resistance to photoconductor contamination is excellent.

  Examples of the epichlorohydrin rubber include CO: epichlorohydrin homopolymer, ECO: ethylene oxide-epichlorohydrin copolymer, GCO: epichlorohydrin-allyl glycidyl ether copolymer, GECO: epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer. can do. GECO is preferred because of its high ionic conductivity and sulfur crosslinkability.

  The epichlorohydrin rubber preferably has a Mooney viscosity of 30 to 90 ML (1 + 4) 100 ° C.

  (A) When using together acrylonitrile butadiene rubber and epichlorohydrin rubber as a component, it is preferable that the mass ratio is 95 / 5-30 / 70. Ozone deterioration resistance can be effectively improved by making the usage-amount of epichlorohydrin rubber into 5 mass% or more of the sum total of both. In addition, when the amount of the epichlorohydrin rubber used is 70% by mass or less of the total of both, the photoreceptor contamination can be effectively suppressed. More preferably, it is 80/20 to 60/40.

  As the component (b), epoxidized polybutadiene rubber is used. Since the epoxidized polybutadiene rubber has an epoxy group, it reacts more easily with the curing agent (vulcanizing agent) to increase the cross-linking property and improve the ozone deterioration resistance. Further, since the polarity is increased by the epoxy group, the compatibility with the acrylonitrile butadiene rubber is improved, and when added to the acrylonitrile butadiene rubber, the sea-island structure is likely to be formed. Also from this, ozone deterioration resistance can be improved by blending epoxidized polybutadiene rubber with acrylonitrile butadiene rubber.

  Examples of the epoxidized polybutadiene rubber include epoxidized butadiene rubber. Epoxidation can be performed, for example, by the hydrogen peroxide method. The content of epoxy groups contained in the epoxidized polybutadiene rubber is preferably 100 to 10,000 g / eq in terms of epoxy equivalent (mass of polymer containing 1 equivalent of epoxy groups). Furthermore, the terminal and the inside modified | denatured by functional groups, such as hydroxyl groups other than an epoxy group, a carboxyl group, and an amino group, may be sufficient.

  The epoxidized polybutadiene rubber preferably has a number average molecular weight of 500 to 10,000. When the number average molecular weight is 10,000 or less, the effect of plasticizing acrylonitrile rubber or epichlorohydrin rubber at the time of unvulcanization is great, and the extrusion moldability is improved. Furthermore, since the number average molecular weight of the epoxidized polybutadiene rubber is 500 or more, it is not too low in molecular weight, so that it is difficult to bleed, and therefore it is difficult to cause contamination of the photoreceptor. The epoxidized polybutadiene rubber is preferably liquid.

  The main chain of the epoxidized polybutadiene rubber may be either a 1,4-polybutadiene structure or a 1,2-polybutadiene structure, but a 1,2-polybutadiene structure is preferred. Since the main chain of the epoxidized polybutadiene rubber has a 1,2-polybutadiene structure, the glass transition temperature rises and the molecular mobility decreases. Therefore, the crack growth rate of ozone is reduced, and the ozone deterioration resistance and the photoreceptor contamination resistance are better than the 1,4-polybutadiene structure.

  The amount of the epoxidized butadiene rubber as the component (b) is 5 to 40 parts by mass with respect to 100 parts by mass of the component (a). If the amount is less than 5 parts by mass, the improvement in ozone resistance is not sufficient, and if it exceeds 40 parts by mass, the adhesiveness of the surface of the rubber roller after vulcanization increases and sticks to the photoreceptor. More preferably, it is 10-20 mass parts with respect to 100 mass parts of (a) component.

  One or more other rubbers may be added to the conductive elastic composition within a range that does not significantly affect the characteristics of the present invention. Examples of other rubbers include EPDM (ethylene-propylene-diene-copolymer), polybutadiene, natural rubber, polyisoprene, SBR (styrene butadiene rubber), CR (chloroprene), silicon rubber, urethane rubber, fluorine rubber, and the like. It is done.

  The conductive elastic composition can contain a conductive agent for imparting conductivity. Examples of the conductive agent include carbon materials such as carbon black and carbon black graphite; metal compounds such as titanium oxide, tin oxide and zinc oxide; metals such as gold, copper and nickel (for example, metal powder); quaternary ammonium salts and alkali metals An ionic conductive agent such as a salt, a sulfonate, or a composite of polyalkylene glycol and lithium perchlorate can be used. Moreover, these electrically conductive agents can be used individually or in combination of 2 or more types.

  Further, the conductive elastic composition may include a plasticizer, a filler, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, an anti-scorch agent, a dispersing agent, a lubricant, an acid acceptor, etc., if necessary. Formulations can be added at the appropriate time.

The conductive elastic layer of the conductive rubber roller of the present invention preferably has a resistance value in the range of 1 × 10 ⁴ to 1 × 10 ⁶ Ωcm. This resistance value can be appropriately adjusted depending on the composition of various rubbers used, the type of conductive agent, and the amount added. The resistance value Rr (Ωcm) of the conductive elastic layer was measured by leaving the conductive elastic layer in an NN (temperature 23 ° C., humidity 60%) environment for 24 hours or more, and then measuring 500 g on both ends of the conductive support. A 1 kΩ resistor connected in series to a SUS drum by applying a DC voltage of -200 V from one of the conductive support members while pressing the SUS drum with a load of 30 mm and rotating the SUS drum at 30 rpm. From the average value Vr (V) obtained by measuring the voltage applied to the body for 3 seconds, it can be measured at Rr = 200 × 10 ³ / Vr.

  Since the conductive rubber roller of the present invention is used for electrophotographic applications, it is preferable to provide a surface layer in order to control adhesion of toner and external additives, resistance adjustment, and prevention of contamination of the photoreceptor. When a surface layer is provided, a polymer binder having flexibility, abrasion resistance and mechanical strength is used as a binder resin, and a conductive agent as described above is dispersed in these resins to adjust the resistance. The As the polymer binder, polyamide resin, polyurethane resin, polyvinyl butyral resin, fluorine resin, polyester resin, acrylic urethane resin, or the like is used.

  Next, a preferred method for producing the conductive rubber roller of the present invention will be described.

  The above-mentioned various rubbers, conductive agents and other compounding agents are dispersed and kneaded using a general kneader such as a pressure kneader, a Banbury mixer, an open roll, etc. to produce an unvulcanized rubber composition. This unvulcanized rubber composition is formed into a cylindrical shape on a core metal which becomes a conductive support by a molding method such as an extruder, injection molding, compression molding, etc., and then vulcanized can, batch type hot air oven, continuous It is vulcanized by methods such as vulcanization and press vulcanization. Thereafter, in order to adjust the surface property and shape, the conductive rubber roller can be molded using a polishing process such as dry polishing or wet polishing. In the examples to be described later, after the core metal and the unvulcanized rubber composition are integrally extruded using a vent type extruder equipped with a cross head, the end portion is cut off with a standard length, and then heated in a hot air drying furnace. The conductive rubber roller is molded by vulcanization and dry polishing. This is because the core metal and the unvulcanized rubber composition are extruded at the same time with a crosshead extruder, eliminating the interference between the core metal and the rubber and reducing the stress applied to the rubber roller after vulcanization. This is because the deterioration can be improved.

  As a preferable method when the surface layer is provided on the conductive rubber roller of the present invention, the following method may be mentioned. First, a predetermined amount of a conductive agent is added to a solution obtained by dissolving the above polymer binder in a solvent, and the mixture is dispersed using a paint dispersing machine such as a bead mill, a sand mill, a ball mill, or a paint shaker. This is applied to the outer periphery of the conductive elastic layer by a coating method such as dip coating, spray coating or roll coating. Further, the surface layer can be formed on the conductive elastic layer by removing the solvent using a hot air circulating dryer or an infrared drying oven.

  In the conductive rubber roller of the present invention, as the surface treatment method other than providing the surface layer, the outermost surface of the conductive elastic layer is highly crosslinked by irradiating energy rays such as electron beam, ultraviolet ray, X-ray, infrared ray, and plasma. The method of making is also mentioned. Among these, it is particularly preferable to irradiate ultraviolet rays. By irradiating with ultraviolet rays, it is possible to control to desired electrical characteristics, and the adhesiveness and friction coefficient are reduced, so that the adhesion of toner and external additives to the elastic body can be controlled. In an example described later, an ultraviolet ray irradiation device using a low-pressure mercury lamp is used, and the rubber roller is irradiated with ultraviolet rays while rotating, thereby uniformly treating the entire rubber roller to obtain a conductive rubber roller.

  Hereinafter, the present invention will be described specifically by way of examples and comparative examples.

Example 1
The following components were kneaded with a pressure kneader for 30 minutes. Calcium carbonate is added for the purpose of improving abrasiveness.
Acrylonitrile butadiene rubber 100 parts by mass (trade name “Nipol DN219”, manufactured by Nippon Zeon Co., Ltd., acrylonitrile content: 33.5%, Mooney viscosity: 27.0 ML (1 + 4) 100 ° C.)
Epoxylated polybutadiene rubber 1 5 parts by mass (trade name “Adekasizer BF-1000”, manufactured by Asahi Denka Kogyo Co., Ltd., epoxy equivalent: 200 g / eq, number average molecular weight: 1000, 1,2-polybutadiene structure)
・ Conductive carbon black 14 parts by mass (trade name “Ketjen Black EC”, manufactured by Ketjen Black International Co., Ltd.)
・ 20 parts by mass of conductive carbon black 2 (trade name “SEAST SVH”, manufactured by Tokai Carbon Co., Ltd.)
・ Calcium carbonate 20 parts by mass (trade name “Silver W”, manufactured by Shiroishi Kogyo Co., Ltd.)
・ Zinc oxide 5 parts by mass ・ Zinc stearate 1 part by mass Further, di-2-benzothiazolyl disulfide (trade name “Noxeller DM-P”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, tetramethylthiuram 1 part by mass of monosulfide (trade name “Noxeller TS”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) and 1.2 parts by mass of sulfur were added. Thereafter, the mixture was kneaded for 10 minutes to prepare an unvulcanized rubber composition.

Next, the core metal (manufactured by SUS, φ6.0 mm, length 258) was formed by an extrusion molding machine using a crosshead set at 80 ° C. (50 mm diameter vent type extruder, L / D = 16, manufactured by EM Giken). The unvulcanized rubber composition was extruded into a cylindrical shape on the same axis centering around 0.0 mm). Excess rubber up to 10.0 mm from the end of the mandrel was cut to make the length of the unvulcanized rubber composition on the mandrel to 238.0 mm, and then vulcanized at 160 ° C. for 1 hour in a hot air drying furnace. The rubber roller after vulcanization was polished by dry polishing into a crown shape with an outer diameter of the rubber center of φ8.5 mm and an outer diameter of the rubber end of φ8.25 mm. The polished rubber roller was subjected to surface treatment with ultraviolet rays using a low-pressure mercury lamp to obtain a conductive rubber roller. The surface treatment was performed for 100 seconds while rotating the rubber roller at 30 rpm with an ultraviolet intensity of 60 mW / cm ² . The resistance value of the conductive elastic layer was 4.0 × 10 ⁴ Ωcm.
(Example 2)
A conductive rubber roller was produced in the same manner as in Example 1 except that the blending amount of the epoxidized polybutadiene rubber 1 was 15 parts by mass. The resistance value of the conductive elastic layer was 6.7 × 10 ⁴ Ωcm.

(Example 3)
A conductive rubber roller was produced in the same manner as in Example 1 except that the amount of epoxidized polybutadiene rubber 1 was 40 parts by mass. The resistance value of the conductive elastic layer was 2.0 × 10 ⁵ Ωcm.

Example 4
A conductive rubber roller was produced in the same manner as in Example 1 except that the amount of acrylonitrile butadiene rubber was 95 parts by mass and 5 parts by mass of epichlorohydrin rubber was added. In addition, Daiso Co., Ltd. brand name "Epichromer CG105" (Mooney viscosity: 65.0ML (1 + 4) 100 degreeC) was used as epichlorohydrin rubber. The resistance value of the conductive elastic layer was 3.3 × 10 ⁴ Ωcm.

(Example 5)
A conductive rubber roller was produced in the same manner as in Example 1, except that the amount of acrylonitrile butadiene rubber was 70 parts by mass and 30 parts by mass of epichlorohydrin rubber was added. The epichlorohydrin rubber used is the same as in Example 4. The resistance value of the conductive elastic layer was 2.2 × 10 ⁴ Ωcm.

(Example 6)
A conductive rubber roller was produced in the same manner as in Example 1 except that the amount of acrylonitrile butadiene rubber was 30 parts by mass and 70 parts by mass of epichlorohydrin rubber was added. The epichlorohydrin rubber used is the same as in Example 4. The resistance value of the conductive elastic layer was 1.3 × 10 ⁴ Ωcm.

(Comparative Example 1)
A conductive rubber roller was produced in the same manner as in Example 1 except that the epoxidized polybutadiene rubber 1 was not added. The resistance value of the conductive elastic layer was 2.9 × 10 ⁴ Ωcm.

(Comparative Example 2)
A conductive rubber roller was produced in the same manner as in Example 1 except that the blending amount of the epoxidized polybutadiene rubber 1 was 50 parts by mass. The resistance value of the conductive elastic layer was 2.9 × 10 ⁵ Ωcm.

(Comparative Example 3)
A conductive rubber roller was produced in the same manner as in Example 2 except that the epoxidized polybutadiene rubber 1 was changed to the epoxidized polybutadiene rubber 2 having a 1,4-polybutadiene structure and the blending amount thereof was 15 parts by mass. As the epoxidized polybutadiene 2, trade name “Epolide PB3600” (number average molecular weight 5900) manufactured by Daicel Chemical Industries, Ltd. was used. The resistance value of the conductive elastic layer was 1.0 × 10 ⁵ Ωcm.

(Comparative Example 4)
A conductive rubber roller was produced in the same manner as in Example 4 except that the epoxidized polybutadiene rubber 1 was not added. The resistance value of the conductive elastic layer was 2.7 × 10 ⁴ Ωcm.

(Comparative Example 5)
A conductive rubber roller was produced in the same manner as in Example 1 except that the amount of acrylonitrile butadiene rubber was 20 parts by mass and that 80 parts by mass of epichlorohydrin rubber was added. The resistance value of the conductive elastic layer was 1.2 × 10 ⁴ Ωcm.

[Evaluation]
The evaluation method for each item is shown below.

(Photoconductor contamination assessment)
The obtained conductive rubber roller was incorporated as a charging roller for a black all-in-one cartridge of a laser beam printer LBP5500 (manufactured by Canon). In this state, after being left in a constant temperature and humidity chamber at a temperature of 40 ° C. and a humidity of 95% for 7 days, a halftone image was output using LBP5500 in an NN environment (temperature 23 ° C., humidity 60%). Thereafter, the photoconductor was taken out from the cartridge, and the surface of the photoconductor was observed at a magnification of 100 using an optical microscope.

  Rank A was evaluated when there was no defective image due to contamination of the photoreceptor in the halftone image, and no deposits or cracks due to bleeding were observed on the surface of the photoreceptor. A halftone image was evaluated as a rank B when there was no image defect due to the contamination of the photoreceptor and no cracks were observed on the surface of the photoreceptor, but the adhered matter was observed. A halftone image was evaluated as a rank C when an image defect due to contamination of the photoconductor was observed, and an adherent or a crack occurred on the surface of the photoconductor.

(Ozone resistance evaluation)
In order to accelerate the ozone deterioration, a conductive rubber roller was separately prepared for 1500 seconds by extending the irradiation time of ultraviolet rays in the surface treatment process using ultraviolet rays, and used for evaluation of ozone resistance. The conductive rubber roller was incorporated as a charging roller for a black all-in-one cartridge in the same manner as the photoconductor contamination evaluation. In this state, after being left in a constant temperature and humidity chamber at a temperature of 40 ° C. and a humidity of 95% for 7 days, a halftone image was output using LBP5500 in an NN environment (temperature 23 ° C., humidity 60%). Thereafter, the surface of the conductive rubber roller was observed using an optical microscope at a magnification of 500 times.

  There is no image defect due to ozone degradation in the halftone image (such as crack marks on the surface of the conductive rubber roller or charging failure due to the high resistance of the conductive rubber roller), and there is a crack on the surface of the conductive rubber roller. Those not present were rated as rank A. Although there was no image defect due to ozone degradation in the halftone image, a case where a minute crack of 100 μm or less was generated on the surface of the conductive rubber roller was evaluated as Rank B. A case where a defect due to ozone deterioration occurred in a halftone image and a crack exceeding 100 μm was generated on the surface of the conductive rubber roller was evaluated as rank C.

  The evaluation results are shown in Table 1.

実施例１では、エポキシ化ポリブタジエンゴム１を５質量部添加したことによって、感光体汚染評価ランクＡ、耐オゾン劣化評価ランクＢとなった。実施例２では、エポキシ化ポリブタジエンゴム１を１５質量部に増やしたことにより、感光体汚染評価ランクＡ、耐オゾン劣化評価ランクＡと向上した。実施例３では、エポキシ化ポリブタジエンゴム１を４０質量部にさらに増やしたことにより、感光体汚染評価ランクＢ、耐オゾン劣化評価ランクＡとなった。実施例３で感光体汚染評価がＢとなったのは、エポキシ化ポリブタジエンゴムに自着性があるために、感光体に対して導電性ゴムローラが貼り付きやすくなったためである。

In Example 1, addition of 5 parts by mass of the epoxidized polybutadiene rubber 1 resulted in a photoreceptor contamination evaluation rank A and an ozone deterioration evaluation rank B. In Example 2, since the epoxidized polybutadiene rubber 1 was increased to 15 parts by mass, the photoreceptor contamination evaluation rank A and the ozone deterioration evaluation rank A were improved. In Example 3, when the epoxidized polybutadiene rubber 1 was further increased to 40 parts by mass, the photoreceptor contamination evaluation rank B and the ozone degradation resistance evaluation rank A were obtained. The reason for the evaluation of the photoreceptor contamination in Example 3 was B because the epoxidized polybutadiene rubber has a self-adhesive property, so that the conductive rubber roller is easily attached to the photoreceptor.

  In Example 4, 95 parts by mass of acrylonitrile butadiene rubber and 5 parts by mass of epichlorohydrin rubber were used, and 5 parts by mass of epoxidized polybutadiene rubber 1 was used, so that the photoreceptor contamination evaluation rank A and the ozone degradation resistance evaluation rank A were obtained. . In Example 5, even when the proportion of the epichlorohydrin rubber and the epichlorohydrin rubber was increased with respect to 70 parts by mass of the acrylonitrile butadiene rubber, the photoreceptor contamination evaluation rank A and the ozone deterioration evaluation rank A were similarly obtained. In Example 6, the ratio of the epichlorohydrin rubber and the epichlorohydrin rubber to 30 parts by mass of the acrylonitrile butadiene rubber was further increased, so that the photoreceptor contamination evaluation rank B and the ozone degradation evaluation rank A were obtained. This is because the deposit | attachment considered to have arisen by reaction of calcium carbonate and hydrochloric acid generate | occur | produced.

  In Comparative Example 1, since the epoxidized polybutadiene rubber 1 was not added, the photosensitive member contamination evaluation rank A and the ozone deterioration evaluation rank C were obtained. Therefore, it can be compared in Example 1 that the ozone deterioration resistance is improved by the epoxidized polybutadiene rubber.

  In Comparative Example 2, since the blending amount of the epoxidized polybutadiene rubber 1 was 50 parts by mass, the sticking property to the photoconductor was further increased as compared with Example 3, and the photoconductor contamination evaluation rank C was obtained. The reason why the ozone deterioration resistance was ranked B is considered to be that the blended amount of the epoxidized polybutadiene rubber 1 was increased and an uncrosslinked portion remained.

  In Comparative Example 3, the epoxidized polybutadiene rubber 1 having a 1,2-polybutadiene structure was changed to the epoxidized polybutadiene rubber 2 having a 1,4-polybutadiene structure, so that the photoreceptor contamination evaluation rank B and the ozone deterioration resistance evaluation rank were obtained. B. This shows the superiority of the epoxidized polybutadiene having a 1,2-polybutadiene structure in Example 2.

  In Comparative Example 4, since the epoxidized polybutadiene rubber 1 was not added, the photoreceptor contamination evaluation rank C and the ozone deterioration evaluation rank B were obtained. Therefore, in Example 4, it can be seen that the contamination of the photoreceptor is suppressed by the supplementary effect of the hydrogen chloride of the epoxy group. Moreover, since the epoxidized polybutadiene rubber increases the compatibility with the epichlorohydrin rubber, it is considered that the ozone deterioration resistance is improved in Example 4.

  In Comparative Example 5, since the epichlorohydrin rubber was 80 parts by mass with respect to 20 parts by mass of the acrylonitrile butadiene rubber, the reaction between calcium carbonate and hydrochloric acid became remarkable, the photoreceptor contamination evaluation was rank C, and the ozone deterioration was evaluated. It is thought that it became rank A.

It is a schematic sectional drawing of a conductive rubber roller.

Explanation of symbols

1 Core (conductive support)
2 Conductive elastic layer 3 Surface layer (protective layer)

Claims (6)

In a conductive rubber roller having a conductive elastic layer made of a conductive elastic composition on a conductive support, the conductive elastic composition comprises:
(A) Component: 100 parts by mass of acrylonitrile butadiene rubber alone, or acrylonitrile butadiene rubber and epichlorohydrin rubber,
(B) component: 5-40 mass parts of epoxidized polybutadiene rubber,
A conductive rubber roller comprising:   The conductive rubber roller according to claim 1, wherein the conductive elastic composition contains only acrylonitrile butadiene rubber as the component (a).   2. The conductive rubber roller according to claim 1, wherein the conductive elastic composition contains acrylonitrile butadiene rubber and epichlorohydrin rubber as the component (a).   The conductive rubber roller according to claim 3, wherein a mass ratio of the acrylonitrile butadiene rubber and the epichlorohydrin rubber is 95/5 to 30/70.   The conductive rubber roller according to claim 1, wherein the epoxidized polybutadiene rubber has a number average molecular weight of 500 to 10,000.   The conductive rubber roller according to claim 1, wherein the main chain structure of the epoxidized polybutadiene rubber is a 1,2-polybutadiene structure.

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