JPWO2005103834A1 - Conductive roller - Google Patents

Abstract

The present invention relates to a conductive roller having a low hardness, a low compression set, and a low roller resistance without causing the softener to bleed, and more specifically, formed on the outer periphery of the shaft (2) and the shaft (2). In the conductive roller (1) provided with the elastic layer (3), the component (A): polybutadiene rubber and / or polyisoprene rubber having a cis-1,4-bond content of 90% or more (B ) Component: Liquid polyisoprene rubber, (C) Component: Conductive agent, (D) Component: Peroxide, and the ratio of (A) component to (B) component is within a specific range The present invention relates to a conductive roller (1) using a rubber composition for an elastic layer (3).

Description

  The present invention relates to a conductive roller, and more particularly to a conductive roller used in an electrophotographic copying apparatus such as a copying machine, a facsimile machine, and a printer.

  In recent years, in an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, a contact method is generally used instead of a corona discharge method in order to prevent generation of ozone. In the contact type image forming apparatus, a roll-shaped conductive member, that is, a conductive roller, is frequently used as a developing roller, a transfer roller, a charging roller, a paper feeding roller, a cleaning roller, a pressure roller for fixing, and the like. Yes.

  In order to obtain a high-quality image using the image forming apparatus, the conductive roller needs to have a low hardness, and usually includes a shaft and an elastic layer disposed on the outer periphery of the shaft. It is. Here, the elastic layer of the conductive roller is mainly composed of solid rubber components such as natural rubber (NR), epichlorohydrin rubber (ECO), ethylene / propylene / diene rubber (EPDM), acrylonitrile / butadiene rubber (NBR), etc. A rubber composition containing a conductive agent such as carbon black, a metal oxide, or an ionic conductive agent in order to impart conductivity, and a large amount of a softening agent to further reduce the hardness. Is generally used (see Japanese Patent Application Laid-Open No. 5-117434, International Publication No. 91/10942 pamphlet).

  However, when a rubber composition containing a large amount of softener is used for the elastic layer of the conductive roller, the compression set of the elastic layer of the conductive roller becomes large, and image unevenness occurs due to deformation at the time of roll pressure contact. There was a problem such as. There is also a problem that the softening agent bleeds on the surface of the conductive roller and contaminates the photoreceptor.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a conductive roller having a low hardness, a small compression set and a low roller resistance, without causing the softener to bleed.

  As a result of intensive investigations to achieve the above object, the present inventors have found that a polybutadiene rubber and / or polyisoprene rubber having a high cis-1,4-bond content is liquid as a softening agent together with a conductive agent and a peroxide. By using a rubber composition blended with polyisoprene rubber for the elastic layer of the conductive roller, the softening agent does not bleed on the surface, the hardness is low, the compression set is small, and the roller resistance is low. Has been found, and the present invention has been completed.

That is, the first conductive roller of the present invention is a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft.
Component (A): For polybutadiene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) component: The rubber composition which mix | blends peroxide, and the mass ratio (A / B) of the said (A) component and the said (B) component is 100 / 30-100 / 100 said It is used for an elastic layer.

  In the suitable example of the 1st electroconductive roller of this invention, the content rate of said (C) component: conductive agent in the said rubber composition for elastic layers is 10-17 mass%.

  In another preferable example of the first conductive roller of the present invention, the content of the component (D): peroxide in the rubber composition for an elastic layer is 0.5 to 1.5% by mass.

The second conductive roller of the present invention is a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft.
Component (A): For polyisoprene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) component: The rubber composition which mix | blends peroxide, and the mass ratio (A / B) of the said (A) component and the said (B) component is 100 / 30-100 / 100 said It is used for an elastic layer.

  In the suitable example of the 2nd electroconductive roller of this invention, the content rate of said (C) component: conductive agent in the said rubber composition for elastic layers is 10-20 mass%.

  In another preferable example of the second conductive roller of the present invention, the content of the component (D): peroxide in the rubber composition for an elastic layer is 3.0 to 6.0% by mass.

Furthermore, the third conductive roller of the present invention is a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft.
Component (A): For polybutadiene rubber and polyisoprene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) Component: Peroxide is blended, and the mass ratio (BR / IR) of polybutadiene rubber (BR) and polyisoprene rubber (IR) in component (A) is 90/10 to 60 / 40, and a rubber composition having a mass ratio (A / B) between the component (A) and the component (B) of 100/10 to 100/40 is used for the elastic layer.

  In the suitable example of the 3rd electroconductive roller of this invention, the content rate of the said (D) component: peroxide in the said rubber composition for elastic layers is 0.5-2.0 mass%.

The third conductive roller of the present invention has an Asker C hardness of 45 to 75 °, and excludes the indentation depth D ₁ and the load measured with a Fischer hardness tester using a conical indenter under a load of 100 N. The creep [(D ₂ −D ₁ ) / D ₁ × 100%] calculated from the later deformation depth D ₂ is preferably −30 to 0%.

  In the conductive roller of the present invention, the microstructure of the polybutadiene rubber and polyisoprene rubber as the component (A) can be obtained by an infrared absorption spectrum method. The liquid polyisoprene rubber as the component (B) is liquid at room temperature (25 ° C.).

  In another preferred embodiment of the conductive roller of the present invention, the component (D): peroxide is 1,1-di (t-butylperoxy) cyclohexane and / or 1,1-di (t-hexylper Oxy) -3,3,5-trimethylcyclohexane.

  According to the present invention, in a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft, polybutadiene rubber and / or polyisoprene rubber having a high cis-1,4-bond content in the elastic layer By using a rubber composition containing liquid polyisoprene rubber as a softening agent together with a conductive agent and a peroxide, the softening agent does not bleed on the surface, the hardness is low, and the compression set is small. A conductive roller having low roller resistance can be provided.

It is sectional drawing of an example of the electroconductive roller of this invention.

Hereinafter, the conductive roller of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an example of a conductive roller of the present invention. The illustrated conductive roller 1 includes a shaft 2 and an elastic layer 3 formed on the outer periphery of the shaft 2. In the conductive roller of the present invention, the elastic layer 3 has
(B) component: liquid polyisoprene rubber, (C) component: conductive agent, and (D) component: excess (A) component: for polybutadiene rubber having a cis-1,4-bond content of 90% or more A first rubber composition comprising an oxide and having a mass ratio (A / B) of the component (A) to the component (B) of 100/30 to 100/100,
Component (A): Polyisoprene rubber having a cis-1,4-bond content of 90% or more, Component (B): Liquid polyisoprene rubber, Component (C): Conductive agent, Component (D): A second rubber composition comprising a peroxide and having a mass ratio (A / B) of the component (A) to the component (B) of 100/30 to 100/100, or
Component (A): Polybutadiene rubber and polyisoprene rubber having a cis-1,4-bond content of 90% or more, (B) component: liquid polyisoprene rubber, (C) component: conductive agent, (D ) Component: a peroxide, and the mass ratio (BR / IR) of the polybutadiene rubber (BR) and the polyisoprene rubber (IR) in the component (A) is 90/10 to 60/40. And a third rubber composition having a mass ratio (A / B) between the component (A) and the component (B) of 100/10 to 100/40 is used.

  Since the rubber composition used for the conductive roller of the present invention contains a liquid polyisoprene rubber having a molecular weight larger than that of a normal softener as a reactive softener, there is no bleeding out when used as a softener.

The rubber composition used for the conductive roller of the present invention includes (A) component: polybutadiene rubber and / or polyisoprene rubber having a cis-1,4-bond content of 90% or more as a rubber component. If the cis-1,4-bond content of the polybutadiene rubber or polyisoprene rubber of component (A) is less than 90%, it will be compatible with the liquid polyisoprene rubber of component (B), so a sea-island structure cannot be formed, and carbon black The conductive agent such as carbon black is dispersed uniformly. As a result, it is considered that the addition of a small amount of conductive material such as carbon black results in high resistance without forming a conductive path. Although not particularly limited, the polybutadiene rubber as the component (A) has a vinyl bond content of 5% or less and a Mooney viscosity ML _{1 + 4} (100 ° C.) in the range of 25-60. On the other hand, the polyisoprene rubber as the component (A) preferably has a vinyl bond content of 5% or less and a Mooney viscosity ML _{1 + 4} (100 ° C.) in the range of 70-80. If the Mooney viscosity ML _{1 + 4} (100 ° C) of the polyisoprene rubber of component (A) is less than 70, there is a problem in the blending of the rubber component. If it is higher than 80, the structure of the conductive agent is destroyed in the kneading process. It will be. In addition, the said rubber composition can use together the said polybutadiene rubber and polyisoprene rubber as a rubber component, and may contain the other rubber component in the range which does not impair the objective of this invention.

  The rubber composition used for the conductive roller of the present invention contains (B) component: liquid polyisoprene rubber as a softening agent. When the polyisoprene rubber as the component (B) is solid, the structure of carbon black is easily broken during kneading, and good conductivity cannot be obtained. Although not particularly limited, the liquid polyisoprene rubber as the component (B) preferably has a weight average molecular weight (Mw) of 20,000 to 50,000.

  In the first and second rubber compositions used for the elastic layer of the conductive roller of the present invention, the mass ratio of the polybutadiene rubber or polyisoprene rubber as the component (A) to the liquid polyisoprene rubber as the component (B) ( A / B) is in the range of 100/30 to 100/100, that is, the blending amount of component (B) liquid polyisoprene rubber is 30 with respect to 100 parts by mass of component (A) polybutadiene rubber or polyisoprene rubber. It is the range of -100 mass parts. When the blending amount of the liquid polyisoprene rubber as the component (B) is less than 30 parts by mass with respect to 100 parts by mass of the polybutadiene rubber or the polyisoprene rubber as the component (A), the Mooney viscosity of the rubber composition becomes too high. Structure breakdown occurs, and good conductivity cannot be obtained. On the other hand, when it exceeds 100 parts by mass, the Mooney viscosity of the rubber composition becomes too low, and kneading with a kneader becomes difficult.

  In the third rubber composition used for the elastic layer of the conductive roller of the present invention, the mass ratio (A / B) between the component (A) and the component (B) is in the range of 100/10 to 100/40. That is, the compounding quantity of the said (B) component is the range of 10-40 mass parts with respect to 100 mass parts of said (A) component. When the blending amount of the liquid polyisoprene rubber as the component (B) is less than 10 parts by mass with respect to the total of 100 parts by mass of the polybutadiene rubber and the polyisoprene rubber as the component (A), the Mooney viscosity of the rubber composition becomes too high, and carbon Black structure destruction occurs, and good conductivity cannot be obtained. On the other hand, when it exceeds 40 parts by mass, the Mooney viscosity of the rubber composition becomes too low, and kneading with a kneader or the like becomes difficult.

  In the component (A) of the third rubber composition, the mass ratio (BR / IR) of the high cis-polybutadiene rubber (BR) to the high cis-polyisoprene rubber (IR) is 90 / 10-60. The range is / 40. When the content of high cis-BR in the component (A) exceeds 90% by mass, the rubber composition is deteriorated by kneading with a kneader of the rubber composition, or buggy or sheet punching occurs in the sheeting operation. On the other hand, when the content of high cis-BR in the component (A) is less than 60% by mass, the rubber composition is closely adhered to the rotor by kneading with a kneader, or the rubber composition is It may stick to the roll.

The rubber composition further contains (C) component: a conductive agent. By adding a conductive agent to the rubber composition, the resistance value of the rubber composition can be adjusted as appropriate, and the roller resistance of the conductive roller using the rubber composition can be adjusted to a desired range. Here, the conductive roller of the present invention is not particularly limited, but the roller resistance is preferably 10 ³ to 10 ⁹ Ω.

As the conductive agent, an electronic conductive agent such as carbon black is preferable. Here, as the carbon black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, etc., carbon black for color subjected to oxidation treatment, pyrolytic carbon black, ketjen black And conductive carbon such as acetylene black. These carbon blacks may be used alone or in combination of two or more. The carbon black is not particularly limited, but preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 30 to 250 m ² / g and a DBP (dibutyl phthalate) absorption of 120 to 250 mL / 100 g. .

  In the first conductive roller of the present invention, the content of the conductive agent is preferably 10 to 17% by mass of the rubber composition. If the content of the conductive agent is less than 10% by mass in the rubber composition, the conductivity of the rubber composition may be low, and desired conductivity may not be imparted to the conductive roller. In some cases, the image becomes too high and a good image cannot be obtained.

  In the second conductive roller of the present invention, the content of the conductive agent is preferably 10 to 20% by mass of the rubber composition. If the content of the conductive agent is less than 10% by mass in the rubber composition, the conductivity of the rubber composition may be low, and desired conductivity may not be imparted to the conductive roller. In some cases, the image becomes too high and a good image cannot be obtained.

  Furthermore, in the third conductive roller of the present invention, the content of the conductive agent is preferably 12.4 to 20.1% by mass of the rubber composition. If the content of the conductive agent is less than 12.4% by mass in the rubber composition, the conductivity of the rubber composition may be low, and desired conductivity may not be imparted to the conductive roller. In some cases, the image becomes too high and a good image cannot be obtained.

  The rubber composition further contains (D) component: peroxide as a crosslinking agent. By crosslinking the rubber composition with a peroxide, the compression set is reduced.

  Examples of the peroxide include 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t -Hexylperoxy) cyclohexane, di (2-t-butylperoxyisopropyl) benzene and the like. Among these, 1,1-di (t-butylperoxy) cyclohexane and 1,1-di (t- Hexylperoxy) -3,3,5-trimethylcyclohexane is particularly preferred. As these peroxides, for example, commercially available products such as Perhexa C-40, Perhexa TMH, Perhexa 3M, etc. manufactured by NOF Corporation can be used.

  In the first conductive roller of the present invention, the peroxide content is preferably 0.5 to 1.5% by mass of the rubber composition. In the first conductive roller of the present invention, if the peroxide content is less than 0.5% by mass in the rubber composition, the rubber composition cannot be sufficiently crosslinked, compression set increases, and 1.5% by mass. If it exceeds%, the hardness of the rubber composition becomes too high, and a conductive roller having a desired hardness may not be obtained. Here, the first conductive roller of the present invention using the rubber composition preferably has an Asker C hardness of 45 to 75 degrees and a compression set of 5 to 20%.

  In the second conductive roller of the present invention, the content of the peroxide is preferably 3.0 to 6.0% by mass of the rubber composition. In the second conductive roller of the present invention, if the peroxide content is less than 3.0% by mass in the rubber composition, the rubber composition cannot be sufficiently crosslinked, compression set increases, and 6.0% by mass. If it exceeds%, the hardness of the rubber composition becomes too high, and a conductive roller having a desired hardness may not be obtained. Here, the second conductive roller of the present invention using the rubber composition preferably has an Asker C hardness of 45 to 75 degrees and a compression set of 5 to 20%.

Furthermore, in the third conductive roller of the present invention, the content of the peroxide is preferably 0.5 to 2.0% by mass of the rubber composition. In the third conductive roller of the present invention, if the peroxide content is less than 0.5% by mass in the rubber composition, the rubber composition cannot be sufficiently crosslinked, compression set increases, and 2.0% by mass. If it exceeds%, the hardness of the rubber composition becomes too high, and a conductive roller having a desired hardness may not be obtained. Here, the third conductive roller of the present invention using the rubber composition preferably has an Asker C hardness of 45 to 75 °, and a Fischer hardness tester is used under a load of 100 N using a conical indenter. The creep [(D ₂ −D ₁ ) / D ₁ × 100%] calculated from the indentation depth D ₁ measured in step ₁ and the deformation depth D ₂ after removing the load is -30 to 0%. preferable. When the Asker C hardness of the conductive roller is less than 45 °, sufficient hardness as the conductive roller may not be ensured. When the Asker C hardness exceeds 75 °, the photosensitive drum and the toner are damaged. At the same time, the durability of the conductive roller may be reduced. Also, if the creep of the conductive roller is less than -30%, the residual strain is too large, and if the conductive roller is left in pressure contact (that is, assembled in a toner cartridge) for a long period of time or at a high temperature, the image is conductive. The horizontal stripe resulting from the roller may be generated.

  The third conductive roller of the present invention is particularly preferable for conveying toner having a toner diameter of 3 to 13 μm. The horizontal stripes are generated when toner enters the blade pressing trace. Therefore, if the pressing trace is smaller than the toner diameter, the occurrence of lateral stripes can be effectively prevented. The third conductive roller of the present invention has a pressing trace of 2 μm or less and is suitable for conveying toner of 3 μm or more.

  In addition to the components (A), (B), (C), and (D), the rubber composition includes various compounding agents that are commonly used in the rubber industry, such as fillers, zinc oxide , Stearic acid and the like can be appropriately selected and blended within a range not impairing the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition is composed of (A) component: polybutazine rubber and / or polyisoprene rubber, (B) component: liquid polyisoprene rubber, (C) component: conductive agent, and (D) component: peroxide. And various compounding agents appropriately selected as necessary, and can be produced by a known method.

  The shaft of the conductive roller of the present invention is not particularly limited as long as it has good conductivity. For example, a metal core made of a metal such as iron, stainless steel, or aluminum, or a hollow interior is hollowed out. A metal shaft such as a metal cylinder can be used.

  The conductive roller of the present invention can be used as a developing roller and a toner supply roller of an image forming apparatus. The method for producing the conductive roller is not particularly limited. For example, the rubber composition is injected into a mold having a desired shape in which a metal shaft is disposed at the center and crosslinked. Can be manufactured.

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  A rubber composition having the formulation shown in Table 1 and Table 2 was prepared, and the obtained rubber composition was injected into a metal mold having a core metal having an outer diameter of 6 mm, and heated at 160 ° C. for 30 minutes. The composition was crosslinked to prepare a rubber roller having an outer diameter of 16 mm and a length of 240 mm. Both ends of the obtained roller were cut by about 5 mm, and an evaluation roller having a total length of 230 mm was produced. The obtained evaluation roller was allowed to stand at room temperature for 14 days to check for bleeding. Further, the hardness, compression set and roller resistance of the evaluation roller were measured by the following methods. The results are shown in Tables 1 and 2.

(1) Hardness The Asker C hardness of the roller was measured using an Asker C hardness meter [manufactured by Kobunshi Keiki Co., Ltd.].

(2) Compression set In accordance with JIS K-6301, a test piece with a diameter of 29 mm and a height of 12.7 mm was compressed 25% in the height direction and left in an oven at 70 ° C. for 22 hours. The residual strain at 30 minutes after removal was determined.

(3) Roller resistance A load of 500 gf was applied to both ends of the roller, and the resistance of the roller was measured under the conditions of an applied voltage of 10 V, a room temperature of 25 ° C., and a humidity of 50% using a resistance measuring device R8340 (manufactured by Advantest). .

* 1 JSR high cis BR, BR02LL, cis-1,4-bond content = 94%, Mooney viscosity ML _{1 + 4} (100 ° C.) = 28.
* 2 JSR high cis BR, BR730, cis-1,4-bond content = 97%, Mooney viscosity ML _{1 + 4} (100 ° C.) = 55.
* 3 Low cis BR, BR1241, cis-1,4-bond content = 35%, Mooney viscosity ML _{1 + 4} (100 ° C.) = 35.
* 4 Kuraray liquid polyisoprene rubber, LIR-30, weight average molecular weight (Mw) = 29,000.
* 5 Liquid polybutadiene oligomer manufactured by Nippon Soda, B-2000.
* 6 Toka Carbon Toka Black, TB # 5500, N ₂ SA = 225m ² / g, DBP oil absorption = 155mL / 100g.
* 7 Perhexa C-40, 1,1-di (t-butylperoxy) cyclohexane, manufactured by NOF Corporation.
* 8 The kneaded rubber stuck to the rotor and could not be discharged from the kneader.

* 4, * 6, * 7 are the same as Table 1.
* 9 Nippon Zeon high cis polyisoprene rubber, Nipol IR2200L, cis-1,4-bond content = 98%, Mooney viscosity ML _{1 + 4} (100 ° C.) = 70.

  As is apparent from Table 1, in the examples using the rubber composition containing polybutadiene rubber or polyisoprene rubber (A) having a high cis-1,4-bond content, liquid polyisoprene rubber (B), and a conductive agent. The conductive roller had no bleed, low hardness, low compression set, and sufficiently low roller resistance.

  On the other hand, the rollers of Comparative Examples 5 and 6 have no bleed, low hardness and low compression set, but the polybutadiene rubber and the softening agent are compatible and carbon black is uniformly dispersed, so that a conductive path is formed. The roller resistance increased.

  Further, in the rollers of Comparative Examples 7 and 8, the carbon black structure was broken and good conductivity was not obtained, and in the rollers of Comparative Examples 9 and 10, the Mooney viscosity of the rubber composition was too low and mixed. Kneading was difficult.

  Next, a rubber composition having the formulation shown in Table 3 was prepared, and the obtained rubber composition was injected into a mold in which a core metal having an outer diameter of 8 mm was previously mounted, and heated at 155 ° C. for 30 minutes. The composition was crosslinked to prepare a rubber developing roller having an outer diameter of 21 mm. With respect to the obtained developing roller, an Asker C hardness meter was measured by the above method, and further, creep and grindability were measured and evaluated by the following method. Further, the developing roller was incorporated into a printer, and the presence or absence of lateral stripes was examined by the following method. These results are shown in Table 3.

(4) Creep Using a Fischer hardness tester, measure the indentation depth D ₁ using a conical indenter under a load of 100 N, and then measure the deformation depth D ₂ after removing the load. And the following formula:
Formula: Creep = (D ₂ −D ₁ ) / D ₁ × 100 (%)
From this, creep was calculated.

(5) Grindability In accordance with JIS B0601, the surface roughness (Rk) of the developing roller was measured using a shape measuring instrument “Surfcom” [manufactured by Tokyo Seimitsu Co., Ltd.]. Here, the case where the surface roughness (Rk) was in the range of 6 to 10 μm was considered good. In addition, chatter marks and ground marks on the surface of the developing roller were visually observed to evaluate the surface property of the developing roller. In Table 3, ◎ indicates that there are no chatter marks and no cuts, ○ indicates that there are some chatter marks but does not affect the image, × indicates that the chatter marks can be clearly confirmed, and the image is bad. Show.

(6) Occurrence of transverse stripes The test developing roller was incorporated in a printer and left at 50 ° C for 5 days, and then halftone printing was performed to evaluate the occurrence of transverse stripes originating from the developing roller. The case where the horizontal streak disappeared before printing 10 sheets was marked as ◯, and the others were marked as x.

* 4, * 6, * 7, * 9 are the same as Table 1 and Table 2.
* 10 High cis polybutadiene rubber manufactured by Nippon Zeon Co., Ltd., BR1220L, cis-1,4-bond content = 97%, Mooney viscosity ML _{1 + 4} (100 ° C.) = 29.
* 11 Organized oxide manufactured by NOF Corporation, Perhexa TMH, 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane.
* 12 “Nobelite A”, manufactured by Nitto Flour Chemical Co., Ltd.

  As is apparent from Table 3, the developing roller of the example using a rubber composition containing a high cis-polybutadiene rubber, a high cis-polyisoprene rubber, and a liquid polyisoprene rubber in a specific ratio as an elastic layer is Since the C hardness is in a predetermined range and the absolute value of creep is small (residual strain is small), the use of the developing roller in a printer can prevent the occurrence of lateral stripes due to the developing roller.

  Next, using a 3L kneader manufactured by Moriyama Seisakusho, the rubber composition having the formulation shown in Table 4 was kneaded to obtain an unvulcanized rubber composition. A predetermined amount of the unvulcanized rubber composition was injected into a mold on which a shaft was previously mounted, and heated in an oven heated to 170 ° C. for 30 minutes to crosslink the rubber composition. Next, the crosslinked roller was taken out of the mold, cooled, and then polished to a predetermined roller diameter using a polishing machine manufactured by Mizuguchi Seisakusho. The obtained conductive roller was allowed to stand at room temperature for 14 days to confirm the presence or absence of bleeding. Further, the hardness, compression set and stationary roller resistance of the conductive roller were measured by the above methods. The results are shown in Table 4.

* 4, * 6, * 9, * 10, * 11 are the same as Tables 1 to 3.

  As apparent from Table 4, by making the BR / IR ratio in the component (A) in the range of 90/10 to 60/40, the workability of the rubber composition can be improved, the hardness of the roller and the permanent compression On the other hand, when the strain was out of this range, workability deteriorated.

Claims (11)

In a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft,
Component (A): For polybutadiene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) component: The rubber composition which mix | blends peroxide, and the mass ratio (A / B) of the said (A) component and the said (B) component is 100 / 30-100 / 100 said A conductive roller characterized by being used for an elastic layer. In a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft,
Component (A): For polyisoprene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) component: The rubber composition which mix | blends peroxide, and the mass ratio (A / B) of the said (A) component and the said (B) component is 100 / 30-100 / 100 said A conductive roller characterized by being used for an elastic layer. In a conductive roller comprising a shaft and an elastic layer formed on the outer periphery of the shaft,
Component (A): For polybutadiene rubber and polyisoprene rubber having a cis-1,4-bond content of 90% or more,
(B) component: liquid polyisoprene rubber;
(C) component: a conductive agent,
(D) Component: Peroxide is blended, and the mass ratio (BR / IR) of polybutadiene rubber (BR) and polyisoprene rubber (IR) in component (A) is 90/10 to 60 / 40, and a rubber composition having a mass ratio (A / B) between the component (A) and the component (B) of 100/10 to 100/40 is used for the elastic layer. roller.   2. The conductive roller according to claim 1, wherein in the rubber composition, the content of the component (C): conductive agent is 10 to 17% by mass.   3. The conductive roller according to claim 2, wherein in the rubber composition, the content of the component (C): conductive agent is 10 to 20% by mass.   2. The conductive roller according to claim 1, wherein in the rubber composition, the content of the component (D): peroxide is 0.5 to 1.5 mass%.   3. The conductive roller according to claim 2, wherein in the rubber composition, the content of the component (D): peroxide is 3.0 to 6.0 mass%.   4. The conductive roller according to claim 3, wherein in the rubber composition, the content of the component (D): peroxide is 0.5 to 2.0 mass%.   The conductive roller according to claim 1, wherein the component (D): peroxide is 1,1-di (t-butylperoxy) cyclohexane.   The conductive component according to any one of claims 1 to 3, wherein the component (D): peroxide is 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane. Sex roller. Asker C hardness is 45-75 °,
Creep [(D ₂ −D ₁ ) / D calculated from the indentation depth D ₁ measured with a Fischer hardness tester using a conical indenter under a load of 100 N and the deformation depth D ₂ after removing the load The conductive roller according to claim 3, wherein ₁ × 100%] is −30 to 0%.

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