JP2006084726A - Conductive roll and image forming apparatus equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roll which has small environmental variation and resistance change with time and can suppress resistance variations and is suitable in cleaning adequacy, and an image forming apparatus using the same. <P>SOLUTION: The conductive roll has a substrate elastic layer including at least one or more conductive elastic layers and a conductive surface layer provided on the outer peripheral surface of a conductive base. The substrate elastic layer consists essentially of epichlorohydrin rubber, acrylonitrile butadiene rubber, and an electron conductive conducting agent. Here, (1) a volume resistance value is 10<SP>7</SP>to 10<SP>9</SP>Ω in an environment of 22°C and 55% RH and (2) the difference between common logarithm values of volume resistance values at 28°C 85% RH and 10°C 15% RH is ≤0.5. Further, (3) a quantity of change in volume resistance value when a current of 20 μA is applied continuously for 25 hours in the environment of 10°C and 15% RH is ≤0.5 in terms of common logarithmic value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive roll used in an image forming apparatus using an electrophotographic system such as a copying machine, a laser printer, a facsimile, and a composite OA apparatus thereof, and an image forming apparatus including the conductive roll.

  In the image formation using the electrophotographic method, a uniform charge is formed on an image carrier (photosensitive member), an electrostatic latent image is formed by a laser or the like that modulates an image signal, and then the static toner is charged with charged toner. The electrostatic latent image is developed to form a toner image. Next, the toner image is formed by forming a desired transfer image by electrostatically transferring the toner image directly to a recording material medium through an intermediate transfer member.

  As described above, in an image forming apparatus using an electrophotographic system, a charging process for forming a uniform charge on an image carrier is performed. One method for performing such charging treatment is a contact charging method. A charging roll is generally used as a charging member used in the contact charging method. It is known that the charging mechanism on the surface of the photosensitive drum by the charging roll described above is based on Paschen's law discharge in the minute space between the charging roll and the photosensitive drum. The contact-type charging roll is brought into contact with the photosensitive drum made of a metal substrate with a predetermined pressing force, and rotates in contact with the rotation of the photosensitive drum. Therefore, the charging roll does not have sufficient flexibility, and is on the surface. When there is a slight dent, floating occurs between the photosensitive drum and a minute interval between the charging roll and the photosensitive drum varies, resulting in poor charging.

  Therefore, in order to prevent floating with respect to the photosensitive drum, the charging roll has a configuration in which a conductive elastic layer is provided on the outer peripheral surface of the conductive support. For this conductive elastic layer, a vulcanized rubber material such as ethylene propylene-diene rubber (EPDM), urethane rubber, silicon rubber, epichlorohydrin rubber or the like is generally used.

  Further, in the image forming apparatus using the electrophotographic system, in addition to the charging roll, many conductive rolls such as a developing roll, a transfer roll, and a cleaning roll are used. Some of these conductive rolls have a conductive elastic layer formed on the outer peripheral surface of a cylindrical shaft, and a protective layer formed on the outer peripheral surface of the elastic layer.

The conductive roll is used by controlling a resistance value in a semiconductive region (volume resistivity: within a range of about 10 ⁵ to 10 ¹¹ Ωcm). In addition, there is little variation in resistance in the conductive roll, and there is little variation in resistance value in a high temperature and high humidity environment (28 ° C., 85% RH) and a low temperature and low humidity environment (10 ° C., 15% RH). It is necessary to obtain the transfer image quality. However, it is very difficult to control the resistance value of the elastic material in the semiconductive region, and it is almost impossible to stably obtain a desired resistance value by adding normal conductive carbon black to a normal elastic material. Accordingly, when a normal conductive carbon black is added to a normal elastic material to produce a conductive roll, the resistance value of all the conductive rolls needs to be measured and selected, which increases the cost.

  This is because it is difficult to uniformly disperse carbon black in the elastic material, which is caused by poor dispersion. This is because when carbon black is added to a polymer such as a resin material, the conductivity is small when carbon black is added in a small amount, and carbon black forms a conductor circuit from a specific threshold. This is because the middle resistance value cannot be obtained because the conductivity is rapidly improved (for example, see Non-Patent Document 1).

As a method of controlling the resistance value in the semiconductive region, there is a method of using an ionic conductive agent (quaternary ammonium salt or the like) having a small variation in resistance value as a conductive agent. For example, the method of mix | blending an ionic conductive agent with acrylonitrile-butadiene rubber (NBR) is mentioned. In this case, the resistance value of the conductive roll can be controlled to a predetermined resistance region (about 10 ⁶ Ω · cm) by ionic conduction by the ionic conductive agent. However, when only an ionic conductive agent is used as the conductive agent, there is a problem that the electrical resistance is likely to fluctuate due to changes in temperature and humidity.
In addition, since acrylonitrile-butadiene rubber (NBR) itself has high electrical resistance, when the resistance value is adjusted depending only on the ionic conductive agent, the amount of ionic conductive agent added becomes excessive, and problems such as blooming (exudation) occur. Occurs.

  Another method is to use an epichlorohydrin rubber having a higher ethylene oxide group that is more ionically conductive than acrylonitrile-butadiene rubber (NBR) as a resistance adjusting layer for a conductive roll having a two-layer structure. Although the conductive roll using such epichlorohydrin rubber can suppress the change of the electrical resistance with respect to the change of temperature and humidity as compared with the conductive roll using the acrylonitrile-butadiene rubber described above, it was not a satisfactory level.

Or the method of making an ionic conductive agent (quaternary ammonium salt etc.) mix | blended with epichlorohydrin rubber is also mentioned. In this case, in addition to the properties of epichlorohydrin rubber having high ionic conductivity, the resistance value can be controlled to a predetermined resistance region (about 10 ⁵ to 10 ¹¹ Ωcm) by the effect of the ionic conductive agent. Since the conductive roll in which an ionic conductive agent is blended with epichlorohydrin rubber has high ionic conductivity of the epichlorohydrin rubber itself, problems such as variations in electrical resistance and voltage dependence between the individual conductive rolls do not occur. However, even in the conductive roll having such a configuration, there is a problem that the electric resistance is likely to fluctuate due to changes in temperature and humidity.

  In addition, a conductive roll in which an ionic conductive agent (such as a quaternary ammonium salt) and carbon black are blended with epichlorohydrin rubber and acrylonitrile-butadiene rubber has been proposed (see, for example, Patent Document 1). In this technology, an ionic conductive agent and carbon black are added in combination to an elastic material made of epichlorohydrin rubber having high ionic conductivity and acrylonitrile-butadiene rubber having low ionic conductivity, so that the desired electric resistance value can be adjusted. Proposed.

  However, the conductivity developed by carbon black has the problem of poor dispersion of carbon black as described above, and the variation in resistance value cannot be reduced. In addition, since this ionic conductive agent has a low molecular weight, problems such as bleeding of the ionic conductive agent onto the surface of the charging roll due to pressing on the photosensitive drum and long-term standing occur even when the addition amount is very small. There is a case. The bleed contaminates the photosensitive drum, causing deterioration of the photosensitive drum and an image defect. In addition, since the toner adheres to the surface of the charging roll, there may be a problem that a charging failure is caused by the accumulation of the toner.

Further, the end of the roll is covered with an annular sealing material having a resistance value of 10 ¹³ Ωcm or more, and a foam layer (1) containing an ionic conductive agent and a foam layer (2) containing an electronic conductive agent are provided on the outer periphery thereof, Further, a toner contamination prevention layer (3) is provided, and the resistance of each layer is R1>R2> R3 (where R1, R2, and R3 are the foam layer (1), the foam layer (2), and the toner contamination prevention layer ( A conductive roll having a three-layer structure adjusted so as to satisfy the resistance value of 3) is proposed (see, for example, Patent Document 2). However, since this conductive roll has a low surface resistance of the toner contamination prevention layer (3), it is necessary to use this conductive roll as a transfer roll to transfer a toner image onto a narrow paper (such as a postcard). Transfer failure may occur because a large transfer current cannot be applied to the paper portion. In addition, since the conductivity of the foam layer (1) containing the ionic conductive agent is determined by the ionic conductive agent whose movement speed is governed by the temperature, the foam layer (2) containing the electronic conductive agent on the outer periphery thereof. Even if it provides, there is little effect which reduces the environmental variation of resistance value. In addition, such a conductive roll has a three-layer structure, and has a problem in that the process is complicated and expensive, such as covering the end of the roll with a sealing material.

  When the conductive roll is used as the transfer roll, the toner remaining on the intermediate transfer member is transferred to the conductive roll while the next sheet is transported to the conductive roll after the sheet passes through the conductive roll. There is a problem that the conductive roll is stained and the conductive roll is stained, and further, the conductive roll is transferred to the back side of the next sheet and the back side of the sheet is stained.

  In order to eliminate this problem, for example, a) When non-transferring, an electric field is formed between the conductive roll and the image carrier or intermediate transfer member in the direction in which the toner is transferred to the image carrier or intermediate transfer member. And b) a method of cleaning the conductive roll with a cleaning blade or the like.

  However, the method a) cannot exhibit a sufficient cleaning effect when toner aggregates are present on the surface of the conductive roll. Further, even when there is no toner aggregate on the surface of the conductive roll, it is not preferable because a high electric field needs to be applied to the conductive roll for sufficient cleaning.

  On the other hand, in the method b), when the conductive roll is made of a rubber material having a large friction coefficient such as EPDM or urethane rubber (see, for example, Patent Document 3), the conductive roll This is not practical for reasons such as damage to the surface or increased rotational torque.

  As a countermeasure for preventing the back surface of the paper from being stained, there is a method of coating a fluorine-based resin on an elastic body such as EPDM or urethane rubber. As such an example, a conductive roll in which the surface of a foamed elastic body such as silicon rubber or urethane rubber is partially coated in a fine patch shape with a fluororesin or silicon resin can be cited (for example, see Patent Document 4). .

  However, since all of the foamed elastic bodies have foam cell irregularities on the surface, the surface energy of the surface layer is low, toner adhesion is small, and even if a fluorine-based resin is coated, the cleaning blade is used. There was a problem that the scrubbing action could not be fully exhibited.

  As a countermeasure, a conductive roll is proposed in which an elastic body layer is provided on the outer peripheral side of the conductive foam layer, and further, a resin composition in which a fluorine resin or fluororesin particles are dispersed is coated on the surface layer. ing. However, since the conductive roll has a three-layer structure, it takes time and is expensive. Although it is possible to use a method in which a conductive foam layer and an elastic layer are processed by a co-extrusion molding method in order to manufacture at a low cost, it is easy to process when a conductive roll is manufactured using this method. Therefore, the thickness of the elastic body layer needs to be 0.1 mm or more. In this case, since the elastic layer becomes thick, if the pressure contact force is increased in order to obtain a uniform nip width, the mechanical interaction between the photosensitive drum and the transfer roll cannot be ignored, resulting in wear and out of sync. In addition, there is a problem that a problem such as a scratch on the photosensitive drum occurs. Furthermore, when the thickness of the elastic layer is reduced by polishing or the like, problems such as blade turning may occur due to insufficient strength of the elastic layer.

  Further, as a method for cleaning the conductive roll, a cleaning method using a cleaning blade method has been proposed (see, for example, Patent Document 5). In order to obtain high quality transfer image quality in recent years, there is a tendency for the toner to use a spherical toner having a small diameter, and the urethane blade used in the method has a cleaning performance because the toner is reduced in diameter and spherical. In addition, it may be difficult to ensure a system capable of detecting the density by forming a density control patch on the conductive roll.

  On the other hand, the use of a metal blade has been proposed as a method for cleaning the hard and smooth transfer roll surface (see, for example, Patent Document 6). However, a transfer roller suitable for such a cleaning method has not been specifically studied.

  Further, as a conventional transfer roll, for example, a structure in which a first layer made of an elastic body and a second layer made of a resin having a higher resistance than this layer are formed (for example, patents). Reference 7). As a material for the surface layer of such a transfer roll, polycarbonate, polyester, and nylon resin are used as a base. However, when the metal blade described in Patent Document 7 is applied to such a resin material, There is a problem that the surface layer is scratched in a short period of time, leading to cleaning failure and detection failure of the density control patch.

As described above, in the conventional conductive roll, there is little environmental fluctuation of the resistance value, there is little resistance variation in the conductive roll, and cleaning performance can be ensured even when spherical polymerized toner is used. Therefore, it was impossible to stably obtain high quality images over time.
JP 2001-214925 A JP 2000-176539 A Japanese Patent Laid-Open No. 6-1224049 Japanese Patent Laid-Open No. 6-149097 JP-A-10-111628 JP-A-6-324583 Japanese Patent Laid-Open No. 3-202885 Polymer processing, Vol.43, No.4, 1977, Sumita etc.

  An object of the present invention is to solve the conventional problems as described above. That is, the present invention provides a conductive roll excellent in cleaning suitability and a transfer property provided with the same, in which resistance value variation due to environmental fluctuations and resistance change with time due to voltage application are small and resistance variation can be suppressed. It is an object of the present invention to provide an image forming apparatus that is excellent and has little density unevenness in image quality.

The above problems have been solved by the present invention described below.
That is, the present invention
<1> On the outer peripheral surface of the conductive support, at least a base elastic layer including one or more conductive elastic layers, and a conductive surface layer provided on the outer peripheral surface of the base elastic layer in this order. A conductive roll provided,
The conductive elastic roll is characterized in that the base elastic layer satisfies the following conditions (1) to (3).
(1) The volume resistance value (Rv1) in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(2) The difference in the common logarithm of the volume resistance value (Rv1) between 28 ° C. and 85% RH and 10 ° C. and 15% RH is 0.5 or less.
(3) The amount of change in the volume resistance value (Rv1) when a current of 20 μA is continuously applied for 25 hours in an environment of 10 ° C. and 15% RH is 0.5 or less as a common logarithmic value.

<2> On the outer peripheral surface of the conductive support, at least a base elastic layer including one or more conductive elastic layers and a conductive surface layer provided on the outer peripheral surface of the base elastic layer in this order. A conductive roll provided,
The base elastic layer has the following components (A) to (C) as essential components, and the component (C) is 5 to 80 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). It is an electroconductive roll characterized by being formed with the rubber composition contained in the range of a mass part.
(A) Epichlorohydrin rubber (B) Acrylonitrile-butadiene rubber (C) Electronic conductive agent

<3> The component (C) is contained in a range of 5 to 40 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B). <2> It is an electroconductive roll as described in above.

<4> The component (A) is an epichlorohydrin rubber having an ethylene oxide content of 35 to 50 mol%, and the component (B) is an acrylonitrile-butadiene having an acrylonitrile content of 10 to 35 mass%. The conductive roll according to <2> or <3>, which is a rubber.

<5> The blending ratio of the component (A) and the component (B) is a mass ratio, and is in the range of (A) component / (B) component = 80/20 to 20/80. It is an electroconductive roll as described in any one of <2>-<4>.

<6> The conductive roll according to any one of <2> to <5>, wherein the component (C) contains two or more carbon blacks having different DBP oil absorption.

<7> On the outer peripheral surface of the conductive support, at least a base elastic layer including one or more conductive elastic layers and a conductive surface layer provided on the outer peripheral surface of the base elastic layer in this order. A conductive roll provided,
It is an electroconductive roll characterized by satisfying the following conditions (4) to (6).
(4) The volume resistance value (Rv2) of the conductive roll in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(5) The difference of the common logarithm value of the volume resistance value (Rv2) of the said conductive roll in 28 degreeC85% RH and 10 degreeC15% RH is 0.5 or less.
(6) The amount of change in the volume resistance value (Rv2) of the conductive roll by applying a current of 20 μA continuously in an environment of 10 ° C. and 15% RH for 25 hours is 0.5 or less as a common logarithmic value.

<8> The conductive roll according to any one of <1> to <7>, wherein the conductive surface layer is formed of a conductive resin tube in which an electron conductive conductive agent is dispersed. It is.

<9> The surface resistivity (ρs2) of the conductive surface layer is in the range of 1 × 10 ⁷ to 1 × 10 ¹³ Ω / □, and any one of <1> to <8> It is an electroconductive roll as described in one.

<10> The conductive roll according to any one of <1> to <9>, wherein a thickness of the conductive surface layer is in a range of 0.02 to 0.08 mm.

<11> The conductive roll according to any one of <1> to <10>, wherein the conductive surface layer contains a polyimide resin as a main component.

<12> The conductive roll according to any one of <8> to <11>, wherein the electron conductive conductive agent dispersed in the conductive resin tube is oxidized carbon black. It is.

<13> An image forming apparatus that includes at least one conductive roll and forms an image using toner,
The conductive roll is the conductive roll according to any one of <1> to <12>.

<14> An image forming apparatus that includes at least one transfer roll and forms an image using toner,
An image forming apparatus, wherein the transfer roll is the conductive roll according to any one of <1> to <12>.

<15> The image forming apparatus according to <13> or <14>, wherein the toner is a spherical toner having a shape factor SF defined by the following formula (1) of 100 to 140.
Formula (1)
SF =
[(Maximum length of toner particles) ² / (projected area of toner particles)] × π × (1/4) × 100

  The present invention has a resistance value variation due to environmental fluctuations, a resistance change over time due to voltage application, and resistance variation can be suppressed. It is possible to provide an image forming apparatus with less density unevenness of the obtained image quality.

<Conductive roll>
The conductive roll according to the first aspect of the present invention includes a base elastic layer including at least one conductive elastic layer on the outer peripheral surface of the conductive support, and a conductive layer provided on the outer peripheral surface of the base elastic layer. In this order, the base elastic layer satisfies the following conditions (1) to (3).
(1) The volume resistance value (Rv1) in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(2) The difference in the common logarithm of the volume resistance value (Rv1) between 28 ° C. and 85% RH and 10 ° C. and 15% RH is 0.5 or less.
(3) The amount of change in the volume resistance value (Rv1) when a current of 20 μA is continuously applied for 25 hours in an environment of 10 ° C. and 15% RH is 0.5 or less as a common logarithmic value.
In the present invention, the difference between the common logarithmic values of the volume resistance value (Rv1) at 28 ° C. 85% RH and 10 ° C. 15% RH is the difference between these two values. Means the absolute value of

The volume resistance value (Rv1) of the base elastic layer in an environment of 22 ° C. and 55% RH must be in the range of 10 ⁷ to 10 ⁹ Ω, and is 10 ^7.5 to 10 ^8.5 Ω when used as transfer means. The range is preferable, and the range of 10 ^7.6 to 10 ^8.4 Ω is more preferable. If it is less than 10 ⁷ Ω, transfer resistance may occur due to the low resistance value of the conductive roll. If it exceeds 10 ⁹ Ω, a power supply with a large capacity corresponding to this is required. Problems such as an increase in M / C size may occur.

  Conventionally, the conductive roll mainly used has a configuration in which only a foamed elastic layer (a layer corresponding to the base elastic layer of the present invention) is provided on a conductive support added with an ionic conductive agent. . The difference in the common logarithm of the volume resistance value of such a conductive roll between 28 ° C. and 85% RH and 10 ° C. and 15% RH is about 1.5 to 2, and the variation range of the resistance value with respect to environmental fluctuation is large. Therefore, a large capacity power supply corresponding to this was necessary. For this reason, it is difficult to reduce the size and cost of the power source used to apply voltage to the conductive rolls, and it is necessary to control the resistance in a wide range, so a control mechanism for controlling the resistance value is required. Simplification was also difficult.

  However, the conductive roll according to the first aspect of the present invention has a change in resistance value due to environmental fluctuations of about 1/10 or less of the conductive roll when viewed as a whole, so the power supply is smaller than before. -The cost can be reduced, and the control mechanism for controlling the resistance value can be simplified.

  In the conductive roll according to the first aspect of the present invention, the difference in the common logarithm of the volume resistance value (Rv1) of the base elastic layer between 28 ° C. 85% RH and 10 ° C. 15% RH is 0.5 or less. Is essential, 0.3 or less is preferable, and 0.1 or less is more preferable. When the difference between the common logarithm values at 28 ° C. 85% RH and 10 ° C. 15% RH exceeds 0.5, the change range of the resistance value with respect to the environmental change is large, and thus a power supply having a large capacity corresponding to this is required. In addition, since it is necessary to control the resistance in a wide range, a control mechanism for controlling the resistance value is required.

  Conventionally, conductive rolls that are mainly used apply a transfer voltage of 1 kV to 5 KV in order to transfer a toner image onto a transfer material, and the resistance value of the conductive roll changes depending on the applied voltage. When the amount of change in resistance is large, a power supply having a large capacity corresponding to this is required, as in the case where the change width of the resistance value with respect to environmental changes is large. For this reason, it is difficult to reduce the size and cost of the power source used to apply voltage to the conductive rolls, and it is necessary to control the resistance in a wide range, so a control mechanism for controlling the resistance value is required. Simplification was also difficult.

  However, the conductive roll of the first aspect of the present invention has a smaller change in resistance value due to the applied voltage than the conventional conductive roll, so that the power supply can be made smaller and less expensive than the conventional one. It is also easy to simplify the control mechanism for controlling the resistance value.

  The conductive roll according to the first aspect of the present invention has a common logarithmic value of a change in volume resistance value (Rv1) by applying a current of 20 μA continuously for 25 hours in an environment of 10 ° C. and 15% RH of the base elastic layer. It must be 0.5 or less, preferably 0.3 or less, and more preferably 0.1 or less. When the change amount of the volume resistance value (Rv1) by applying the current of 20 μA continuously for 25 hours exceeds 0.5 as a common logarithmic value, the change of the resistance value with respect to the environmental change is large as in the case where the change amount of the resistance value is large. A large power supply is required, and since it is necessary to control the resistance in a wide range, a control mechanism for controlling the resistance value is required.

  In the present invention, the volume resistance value (Rv1) of the base elastic layer, the volume resistance value (Rv2) of the conductive roll described later, the volume resistance value (Rv3) of the conductive surface layer, and the conductivity described later. The surface resistance value (ρs2) and the like of the conductive surface layer shall be measured in a normal temperature and normal humidity environment (22 ° C. and 55% RH) when the temperature and humidity at which these values are measured are not mentioned. That is, the amount of change in the volume resistance value (Rv1 or Rv2) by applying a current of 20 μA continuously for 25 hours under the environment of 10 ° C. and 15% RH in the above (3) and the following (6) is 10 ° C. and 15% RH. The volume resistance value before and after the continuous application of a current of 20 μA under the environment for 25 hours was measured at 22 ° C. and 55% RH, and the difference was obtained.

The volume resistance value (Rv1) of the base elastic layer is a value measured by the following procedure.
As shown in FIG. 1, the volume resistance value (Rv1) of the base elastic layer is obtained by applying a roller-like conductive member (conductive roll) 100 composed of the conductive support 10 and the base elastic layer 20 to a metal plate 40 or the like. In the above, a load of 500 g is applied to both ends of the conductive member 100, a voltage of 1 kV (V) is applied between the conductive support 10 and the metal plate 40, and the current value I after 10 seconds. It is obtained by reading (A) and calculating by the following formula. In addition, in the following drawings, what has the same function attaches | subjects the same code | symbol throughout all the drawings, and the description may be abbreviate | omitted.
Volume resistance value (R) = Voltage (V) / Current (I)

In the present invention, the continuous energization test of the base elastic layer (the amount of change in the volume resistance value (Rv1) by applying a current of 20 μA to the base elastic layer continuously for 25 hours in an environment of 10 ° C. and 15% RH) is: The measurement was performed using the measuring apparatus shown in FIG. FIG. 2 is a schematic cross-sectional view showing a method for measuring a voltage change when a conductive roll is continuously energized. In FIG. 2, reference numeral 500 denotes a conductive roll made of the conductive support 10 and the base elastic layer 20, 502 denotes a metal roll, and the conductive roll 500 can be driven to rotate when the metal roll 502 rotates. The metal roll 502 is in pressure contact. A voltmeter is connected between the conductive roll 500 and the metal roll 502. In the measurement, the measurement was performed while rotating these two rolls.
In actual measurement, in an environment of 10 ° C. and 15% RH, while applying a load of 500 g on both ends of the conductive roll, while pressing the metal roll (outer diameter 30 mm) and rotating the metal roll at 30 rpm, A 20 μA current was continuously applied for 25 hours between the conductive roll and the metal roll.

  The continuous energization test of the underlying elastic layer (the amount of change in the volume resistance value (Rv1) by applying a current of 20 μA to the underlying elastic layer for 25 hours under an environment of 10 ° C. and 15% RH) is shown in FIG. The volume resistance value (Rv1) of the underlying elastic layer before and after applying a current of 20 μA continuously for 25 hours was measured by a method using such a measuring device. The absolute value of the difference in Rv1) was defined as the amount of change in the volume resistance value (Rv1) by applying a current of 20 μA to the underlying elastic layer continuously for 25 hours in an environment of 10 ° C. and 15% RH.

  The conductive roll of the first invention satisfying the conditions (1) to (3) is preferably obtained by satisfying the requirements of the conductive roll of the second invention described below.

The conductive roll according to the second aspect of the present invention includes a base elastic layer including at least one conductive elastic layer on the outer peripheral surface of the conductive support, and a conductive layer provided on the outer peripheral surface of the base elastic layer. A conductive surface layer in this order, wherein the base elastic layer has the following components (A) to (C) as essential components, and component (C) as component (A): And (B) is formed of a rubber composition contained in a range of 5 to 80 parts by mass with respect to 100 parts by mass as a total amount.
(A) Epichlorohydrin rubber (B) Acrylonitrile-butadiene rubber (C) Electronic conductive agent

  Thus, it is essential that the base elastic layer in the conductive roll of the second invention contains the components (A) to (C). Like the conductive roll of the second aspect of the present invention, epichlorohydrin rubber (component (A)) having high ion conductivity and acrylonitrile-butadiene rubber (component (B)) having low ion conductivity were used in combination. By forming the conductive elastic layer from the rubber composition, the conductivity of the conductive elastic layer is governed by ionic conduction, and the voltage dependency of the electrical resistance is reduced. Then, by blending a predetermined amount of an electron conductive conductive agent (component (C)) into this rubber composition, the electrical resistance under low temperature and low humidity becomes low and close to the electrical resistance under high temperature and high humidity. As a result, the electrical resistance value does not fluctuate greatly even under high temperature and high humidity and low temperature and low humidity, and it is difficult to be affected by the environment such as temperature and humidity, that is, the electrical resistance is less dependent on the environment. Further, since no low molecular ion conductive agent is added, there is no problem of blooming, and as a result, contamination of the surface of the conductive member or the surface of the photoreceptor can be prevented.

  The rubber component used in the rubber composition of the base elastic layer in the present invention contains epichlorohydrin rubber (component (A)) and acrylonitrile-butadiene rubber (component (B)). Acrylonitrile-butadiene rubber and epichlorohydrin rubber are highly compatible and uniformly disperse when blended. As a result, the rubber material has a small resistance variation.

  In the present invention, the epichlorohydrin rubber (component (A)) preferably has an ethylene oxide content in the range of 35 to 50 mol%, more preferably in the range of 40 to 48 mol%. preferable. The ethylene oxide content in the single epichlorohydrin rubber may be within the above range, or may be adjusted by blending a plurality of epichlorohydrin rubbers having different ethylene oxide contents.

  The electrical resistance (resistance value) of epichlorohydrin rubber decreases as the ethylene oxide content increases. Therefore, when an ethylene oxide content of less than 35 mol% is used, the amount of epichlorohydrin rubber blended with acrylonitrile butadiene rubber to obtain a predetermined resistance increases, and the electrical resistance becomes more environmentally dependent. May end up. Moreover, in order to obtain a predetermined resistance value, it is necessary to increase the amount of carbon black added, which may cause problems such as increased roll hardness.

  In addition, when the ethylene oxide content exceeds 50 mol% (particularly when it exceeds 65 mol%), the amount of electron conductive conductive agent (for example, carbon black) added to obtain a predetermined resistance value decreases. Since the effect of lowering the electrical resistance under low temperature and low humidity by the electron conductive conductive agent is hardly expressed, the environmental dependency of the electrical resistance may be likely to increase.

  The acrylonitrile-butadiene rubber (component (B)) preferably has an acrylonitrile content in the range of 10 to 35% by mass, and more preferably in the range of 15 to 25% by mass. If the acrylonitrile content is more than 35% by mass, the electrical resistance may be highly dependent on the environment. On the other hand, if the amount is less than 10% by mass, the resistance value of the acrylonitrile-butadiene rubber may be easily increased. For this reason, it is necessary to increase the amount of carbon black added to obtain a predetermined resistance, which may cause problems such as an increase in final roll hardness.

As the epichlorohydrin rubber (component (A)) and acrylonitrile-butadiene rubber (component (B)), the resistance value, hardness, etc. can be easily adjusted according to the purpose of use by using the above-mentioned composition together.
Further, as in the present invention, when the epichlorohydrin rubber (component (A)) and acrylonitrile-butadiene rubber (component (B)) are used in combination as the rubber composition for forming the base elastic layer, the rubber is formed by the component (B). Since the component can be made into a low-viscosity polymer, the extrusion pressure can be reduced and the extrusion skin can be improved in extrusion molding and the like.

The compounding ratio of the epichlorohydrin rubber (component (A)) and the acrylonitrile-butadiene rubber (component (B)) is a mass ratio, and is in the range of (A) component / (B) component = 80/20 to 20/80. It is preferable to set. More preferably, it is in the range of (A) component / (B) component = 75 / 25-40 / 60, and more preferably in the range of (A) component / (B) component = 70 / 30-50 / 50. is there.
That is, when the epichlorohydrin rubber (component (A)) is less than 20 (acrylonitrile-butadiene rubber (component (B) exceeds 80)) in the blending ratio (blending ratio), the conductive member obtained is In some cases, the initial electrical resistance may be high, and when the epichlorohydrin rubber (component (A)) exceeds 80 [acrylonitrile-butadiene rubber (component (B)) is less than 20), the obtained conductive member In some cases, the degree of increase in electrical resistance after application of a direct-current voltage increases.

  In the present invention, in addition to the epichlorohydrin rubber (component (A)) and acrylonitrile-butadiene rubber (component (B)), the rubber composition for forming the base elastic layer may contain other rubber components. . As the other rubber component, chloropyrene rubber, butyl rubber, ethylene-propylene rubber, styrene butadiene rubber and the like can be used, and the content thereof is 100 mass of the total amount of the component (A) and the component (B). It is preferable that it is the range of 1-50 mass parts with respect to a part.

  As described above, the material for forming the base elastic layer includes an epichlorohydrin rubber (A) component, an acrylonitrile-butadiene rubber (B) component, and an electron conductive conductive agent (C) component as essential components, and The content of the component (C) is from 5 to 80 with respect to 100 parts by mass (hereinafter appropriately abbreviated as “part”) of the rubber component (A) and the component (B). A rubber composition set in the range of parts is used.

As content of (C) component with respect to 100 parts of total amounts of said (A) component and (B) component, the range of 5-60 parts is preferable, The range of 5-45 parts is more preferable, 5-40 parts Is more preferable, the range of 10 to 35 parts is particularly preferable, and the range of 15 to 30 parts is most preferable. When the content of the component (C) is in the range of 5 to 80 parts relative to 100 parts of the total amount of the component (A) and the component (B), the resulting conductive member changes in environment and voltage. Thus, the fluctuation range of the electric resistance caused by the above can be effectively reduced.
That is, when the content of the component (C) with respect to 100 parts of the total amount of the component (A) and the component (B) is less than 5 parts, there is no effect of electron conduction that affects the fluctuation range. If it exceeds 80 parts, the hardness of the conductive roll may increase, and problems such as an increase in nip pressure at the nip formed between the conductive roll and a member in contact with the member may occur.

  Examples of the electron conductive conductive agent (component (C)) include metals or alloys such as carbon black, graphite, aluminum, nickel, and copper alloys, tin oxide, zinc oxide, kalim titanate, tin oxide-indium oxide, or oxide. Although metal oxides, such as a tin-antimony oxide complex oxide, etc. are mentioned, Carbon black is preferable among these. Moreover, as said (C) component, it can be used individually by 1 type from the above or in mixture of 2 or more types.

  Carbon black suitable as an electron conductive conductive agent (component (C)) has a property of being bonded in a chain form in a rubber composition to which the carbon black is added. Depending on the length of the chain bond, The resistance value will be different. If this chain bond is long, the conductivity of the underlying elastic layer is improved and its resistance value is lowered. On the other hand, if the chain bond is short, the conductivity of the underlying elastic layer is lowered and the resistance value is increased. That is, when carbon black that forms a long chain bond is added, the amount of carbon black added to develop a desired resistance value can be reduced compared to carbon black that forms a short chain bond, Since the resistance value largely fluctuates due to the change in the addition amount, the above-described variation in the resistance value in the base elastic layer cannot be reduced.

In addition, as the electron conductive conductive agent (component (C)) in the present invention, it is also preferable to use two or more types of carbon black having different characteristics such as surface characteristics.
The length of the chain bond of the carbon black described above depends on the particle size and surface activity of the individual particles of the carbon black. (Dibutyl phthalate) has oil absorption. This DBP oil absorption is expressed by whether the amount (ml) of DBP absorbed by 100 g of carbon black is large or small. The higher the DBP oil absorbency, that is, the greater the amount of oil absorbed, the longer the carbon chain.

If only the carbon black having a high DBP oil-absorbing property is added to the rubber composition to adjust the resistance value of the elastic layer, the resistance value greatly changes even if the addition amount is slightly increased or decreased. Therefore, a predetermined resistance value cannot be imparted to the elastic layer unless the addition amount and dispersion state of carbon black are strictly defined. On the other hand, if only the carbon black having a low DBP oil absorbency is added and the resistance value of the elastic layer is adjusted, the carbon black is substantially less in the rubber composition than the case where only the carbon black having a high DBP oil absorbency is added. Since it disperses uniformly, the rate of change in resistance value with an increase or decrease in the amount added decreases. However, in order to impart a predetermined resistance value to the elastic layer, it is necessary to add a larger amount of carbon black than when adding only carbon black having high DBP oil absorption. As a result, since the blending ratio of carbon black in the rubber composition is increased, when the rubber composition is kneaded with a Banbury mixer, a kneader or the like, the viscosity becomes high and processing becomes difficult. Moreover, the problem that the obtained elastic layer becomes high hardness may generate | occur | produce.
Therefore, it is preferable to use two or more types of carbon black having a high DBP oil absorbability and carbon black having a low DBP oil absorbability that are different in DBP oil absorbency.

  The two or more types of carbon black added to the material for forming the elastic layer may be those having a difference in DBP oil absorption, but if this difference is too small, it is the same as when one type of carbon black is added. May result in Accordingly, carbon black having a certain difference in DBP oil absorption is preferable, and at least one carbon black having a different DBP oil absorption is a carbon black having a DBP oil absorption of 250 ml / 100 g or more (DBP oil absorption). The carbon black having a high oil absorption is preferably 150 ml / 100 g or less (carbon black having a low DBP oil absorption).

The DBP oil absorption of carbon black having a high DBP oil absorption is 280 ml / 100 g or more, and the DBP oil absorption of carbon black having a low DBP oil absorption is more preferably 110 ml / 100 g or less.
In the present invention, as the two or more types of carbon blacks having different DBP oil absorption properties, at least the carbon black having a high DBP oil absorption property and the carbon black having a low DBP oil absorption property may be used. Carbon blacks with different amounts may further be included.

  Specifically, as the carbon black having high DBP oil absorption, for example, HS-500 (manufactured by Asahi Carbon Co., Ltd.) having a DBP oil absorption of 447 ml / 100 g, Ketjen black (Lion Exo (product of Asahi Carbon Co., Ltd.)) And carbon black such as Vulcan XC-72 (manufactured by Cabot Corporation) having a DBP oil absorption amount of 288 ml / 100 g and DBP oil absorption amount of 265 ml / 100 g. Moreover, as carbon black with low DBP oil absorption, Asahi Thermal FT (Asahi Carbon Co., Ltd.) having a DBP oil absorption of 28 ml / 100 g, Asahi Thermal MT (Asahi Carbon Co., Ltd.) having a DBP oil absorption of 35 ml / 100 g are used. ) And the like.

  In general, carbon black having a higher DBP oil absorption tends to have a smaller primary particle size, and the carbon black having a higher DBP oil absorption has a primary particle size in the range of 5 to 50 nm. It is preferable to use carbon black having a low primary property with a primary particle size in the range of 20 to 100 nm.

  As a specific example, when the resistance value of the base elastic layer is adjusted using a mixture of carbon black having high DBP oil absorbency (such as acetylene black) and carbon black having low DBP oil absorbency (such as thermal black), the mixing ratio Is preferably in the range of 1: 1 to 1: 8 by mass ratio (mass of carbon black having high DBP oil absorbency: mass of carbon black having low DBP oil absorbency), and in the range of 1: 2 to 1: 6. More preferably, it is more preferably in the range of 1: 2 to 1: 5.

  When the mass of the carbon black with low DBP oil absorbency is less than 1 when the mass of the carbon black with high DBP oil absorbency is 1, not only the resistance value varies greatly, but also by the increase or decrease of the former addition amount, The resistance value of the elastic layer may change greatly. On the other hand, when the ratio is larger than 8, as described above, the rubber composition at the time of kneading has a high viscosity, so that not only the molding of the elastic layer becomes difficult, but also the hardness of the elastic layer may increase. . Thus, the rapid change of the resistance value of an elastic layer can be suppressed by adjusting the mixing ratio of carbon black having different DBP oil absorbency and the blending amount with respect to the rubber material. At the same time, it is possible to form an elastic layer having a small variation in resistance value with a small amount of addition as compared with the case of carbon black having a low DBP oil absorption.

In addition to the components (A) to (C), a crosslinking agent, a filler, a foaming agent, and the like are appropriately blended in the base elastic layer as necessary. However, it is preferable that an ion conductive conductive agent is not included as a component constituting the base elastic layer in the present invention.
The crosslinking agent is not particularly limited, and conventionally known ones such as thiourea, triazine, sulfur and the like can be mentioned. Examples of the filler include insulating fillers such as silica, talc, clay and titanium oxide, and these may be used alone or in combination. Moreover, as a foaming agent, any of an inorganic type foaming agent and an organic type foaming agent may be used, for example, These may be used independently and may be used together 2 or more types.

  The base elastic layer can be produced by mixing the components (A) to (C) with a mixer such as a tumbler, V-type blender, nauter mixer, Banbury mixer, kneading roll, or extruder. In the production of the base elastic layer in the present invention, the mixing method of each component and the order of mixing are not particularly limited. As a general method, all components are mixed in advance with a tumbler, V blender, etc., and uniformly melt-mixed by an extruder. Depending on the shape of the components, two or more types of molten mixtures in these components are used. Alternatively, a method of melt-mixing the remaining components can be used.

The conductive roll according to the third aspect of the present invention includes a base elastic layer including at least one conductive elastic layer on the outer peripheral surface of the conductive support, and a conductive layer provided on the outer peripheral surface of the base elastic layer. It is the conductive roll which provided the conductive surface layer in this order, Comprising: The conditions of following (4)-(6) are satisfy | filled. The conductive roll of the third aspect of the invention has a base elastic layer similar to the base elastic layer in the conductive roll of the second aspect of the invention described above, and further has a conductive surface layer having the characteristics described below. It is preferably obtained by providing.
(4) The volume resistance value (Rv2) of the conductive roll in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(5) The difference of the common logarithm value of the volume resistance value (Rv2) of the said conductive roll in 28 degreeC85% RH and 10 degreeC15% RH is 0.5 or less.
(6) The amount of change in the volume resistance value (Rv2) of the conductive roll by applying a current of 20 μA continuously in an environment of 10 ° C. and 15% RH for 25 hours is 0.5 or less as a common logarithmic value.

The volume resistance value (Rv2) of the conductive roll provided with at least the base elastic layer and the conductive surface layer must be in the range of 10 ⁷ to 10 ⁹ Ω, and 10 ^7.5 to 10 when used as a transfer means. The range is preferably ^8.5 Ω, and more preferably 10 ^7.6 to 10 ^8.4 Ω. When the Rv2 is less than 10 ⁷ Ω, transfer failure may occur due to the low resistance value of the roll. When the Rv2 exceeds 10 ⁹ Ω, a large-capacity power source corresponding to this is required. Problems such as an increase in M / C size may occur.

  In the conductive roll according to the third aspect of the present invention, the difference in common logarithm of the volume resistance value (Rv2) of the conductive roll between 28 ° C. and 85% RH and 10 ° C. and 15% RH is 0.5 or less. Is essential, 0.3 or less is preferable, and 0.1 or less is more preferable. When the difference between the common logarithm values at 28 ° C. 85% RH and 10 ° C. 15% RH exceeds 0.5, the change range of the resistance value with respect to the environmental change is large, and thus a power supply having a large capacity corresponding to this is required. In addition, since it is necessary to control the resistance in a wide range, a control mechanism for controlling the resistance value is required.

  In addition, each volume resistance value (Rv2) of the said electroconductive roll is a roller-shaped electroconductive member (conductive roll) 100 which consists of the electroconductive support body 10 and the foundation | substrate elastic layer 20 in FIG. Is replaced with a roller-like conductive member (conductive roll) 100 ′ having a conductive support 10 and a base elastic layer 20, and further having a conductive surface layer 30 formed on the outer surface of the conductive support 10. Except for the above, it can be obtained in the same manner as the measurement of the volume resistance value (Rv1) of the underlying elastic layer.

  In the conductive roll of the third aspect of the present invention, the amount of change in the volume resistance value (Rv2) by applying a current of 20 μA continuously for 25 hours in an environment of 10 ° C. and 15% RH of the conductive roll is a common logarithmic value. It must be 0.5 or less, preferably 0.3 or less, and more preferably 0.1 or less. When the change amount of the volume resistance value (Rv2) by applying the current of 20 μA continuously for 25 hours exceeds 0.5 as a common logarithmic value, as in the case where the change width of the resistance value with respect to environmental fluctuation is large, A large power supply is required, and since it is necessary to control the resistance in a wide range, a control mechanism for controlling the resistance value is required.

  In the present invention, the continuous energization test of the conductive roll (the amount of change in the volume resistance value (Rv2) by applying a current of 20 μA to the underlying elastic layer continuously for 25 hours in an environment of 10 ° C. and 15% RH) is: The conductive roll 500 including the conductive support 10 and the base elastic layer 20 in the continuous energization test of the base elastic layer described above includes the conductive support 10 and the base elastic layer 20, and the outer surface of the conductive support 10. Furthermore, it can obtain | require similarly to the continuous energization test of the said foundation | substrate elastic layer except having changed into the electroconductive roll in which the electroconductive surface layer 30 is formed.

The surface resistivity (ρs2) of the conductive surface layer is preferably in the range of 10 ⁷ to 10 ¹³ Ω / □, and more preferably in the range of 10 ⁸ to 10 ¹² Ω / □.
When the surface resistivity of the conductive surface layer is lower than 10 ⁷ Ω / □, a paper having a width smaller than the roll width such as a postcard is transferred in a low temperature and low humidity environment of 10 ° C. and 15% RH. Because the resistance of the paper becomes high and current tends to flow outside the paper at the edge of the paper, the required transfer current cannot be obtained at the edge of the paper, resulting in an image quality defect (paper edge failure) that causes the paper edge to fall white. There is a case.

In addition, when the surface resistivity of the conductive surface layer exceeds 10 ¹³ Ω / □, electric charges easily accumulate on the conductive surface layer, and a potential difference occurs in the roll circumferential direction on the surface of the conductive roll to charge up. In some cases, an image quality defect in which the density increases in a band shape at a roll diameter pitch may occur.

  In the present invention, the surface resistivity can be measured based on JIS K6991 using a circular electrode (for example, “UR probe” of Hiresta IP manufactured by Dia Instruments Co., Ltd.). The method for measuring the surface resistivity will be specifically described below with reference to FIG. FIG. 4 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode.

  The circular electrode shown in FIG. 4 includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided.

The surface resistivity was measured by cutting out a sheet between the cylindrical electrode part C and the ring electrode part D of the first voltage application electrode A and the plate insulator B (width 63.4 mm, length). 230 mm) When a voltage V (V) is applied between the cylindrical electrode portion C and the ring-shaped electrode portion D of the first voltage applying electrode A with the sample S (conductive surface layer in the present invention) being sandwiched This is done by measuring the current I (A) flowing through the.
When measuring the surface resistivity of the sample S, the conductive surface layer is disposed so that the outer peripheral surface thereof is in contact with the cylindrical electrode portion C and the ring-shaped electrode portion D.
At this time, the surface resistivity ρs (Ω / □) of the outer peripheral surface of the conductive surface layer can be calculated by the following equation. Here, in the following formula, d (mm) indicates the outer diameter of the cylindrical electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
Formula ρs = π × (D + d) / (D−d) × (V / I)

The thickness of the conductive surface layer is not particularly limited, but is preferably in the range of 0.02 to 0.08 mm in order to follow the deformation of the base elastic layer with a low pressure. More preferably, it is in the range of 03 to 0.06 mm.
When the thickness of the conductive surface layer is less than 0.02, the thickness of the conductive surface layer is too thin and the strength of the conductive surface layer is insufficient. When the blade is brought into contact with the surface of the conductive roll, the blade Problems such as turning over may occur. On the other hand, if it exceeds 0.08 mm, there may be a problem that the pressure required to follow the deformation of the underlying elastic layer increases.
The film thickness of the conductive surface layer was measured using an eddy current film thickness meter (MP30 manufactured by Fischer).

Further, the Young's modulus of the conductive surface layer of the conductive surface layer is preferably 2000 Mpa or more, and more preferably 3000 Mpa or more.
When the Young's modulus of the conductive surface layer is less than 2000 Mpa, when the blade is brought into contact with the surface of the conductive roll, even if the thickness is not less than 0.02 mm, Due to insufficient strength of the conductive surface layer, the conductive surface layer may be deformed to cause wrinkles and the like, and problems such as blade turning may occur.

As a material that is a main component of the conductive surface layer, for example, a resin material such as polyimide resin, polyphenylene sulfide, polyether sulfide, polyetherimide, polyarylate, or the like can be used. Among these, a polyimide resin is particularly preferable from the viewpoints of strength, heat resistance, and dimensional stability.
More specific examples of the polyimide resin include thermosetting resins such as polypyromellitic acid imide based polyimide resin materials and polybiphenyltetracarboxylic imide based resin materials. Examples thereof include thermoplastic polyimide resins such as polybenzophenone tetracarboxylic acid imide acid resin materials and polyetherimide resins.
In addition, in this invention, a main component means occupying 50 mass% or more in all the materials. That is, it is preferable that 50% by mass or more of the total material of the conductive surface layer is a polyimide resin. Furthermore, in this invention, it is more preferable that 70 mass% or more in all the materials of the said electroconductive surface layer is a polyimide resin, and it is still more preferable that 90 mass% or more is a polyimide resin.

For the conductive surface layer, for example, in order to satisfy the Young's modulus, a resin composition to which an inorganic filler is added can be used. More specifically, molybdenum disulfide and mica having a layered structure as an inorganic filler having an effect of improving wear resistance. Examples thereof include graphite having a plate-like form, boron nitride, potassium titanate fiber, glass fiber, alumina fiber, and filler material having a fiber shape such as silicon carbide fiber.
The resin material to which the inorganic filler is added is a thermosetting resin such as a phenol resin. Examples thereof include thermoplastic resins such as polyethylene terephthalate, polyethylene terephthalate, polycarbonate, ABS resin, polystyrene, polypropylene, and polyamide.

In order to obtain desired conductivity, a conductive agent can be added to the conductive surface layer. As the conductive agent, a known material can be used, but it is preferable to use an electronic conductive conductive agent in terms of effectively suppressing variation in resistance to environmental fluctuations. In the present invention, the conductive surface layer is preferably a conductive resin tube in which an electronic conductive agent is dispersed.
Examples of the electron conductive conductive agent added to such a conductive surface layer include carbon black, graphite, aluminum, nickel, copper alloys and other metals or alloys, tin oxide, zinc oxide, kalim titanate, tin oxide-oxidation. Known metal oxides such as indium or tin oxide-antimony oxide composite oxide can be used.

  Among the electron conductive conductive agents added to these conductive surface layers, it is preferable to use oxidized carbon black (hereinafter sometimes abbreviated as “acidic carbon black”). Acidic carbon black has a functional group such as a carboxyl group on the surface and is compatible with the resin component, so that it can be uniformly dispersed. For this reason, it is possible to reduce the variation in resistance value as described above. In addition, the pH of acidic carbon black is 5 or less. By setting the pH of the acidic carbon black to 5 or less, when a voltage is repeatedly applied to the conductive roll, an excessive current flows in part, thereby further oxidizing the surface of the acidic carbon black. Further, it is possible to prevent the problem that the acidic carbon black characteristics are greatly changed and the resistance of the conductive roll is changed.

  By using acidic carbon black having a pH of 5 or less as the electronic conductive conductive agent added to the conductive surface layer, an excessive current flows in part or it is difficult to be affected by oxidation due to repeated voltage application. Furthermore, due to the effect of oxygen-containing functional groups attached to the surface of acidic carbon black, the dispersibility to the substrate is high, the resistance variation can be reduced, and the electric field dependency is also reduced. Disappear. As a result, resistance change due to energization can be prevented, uniformity of electrical resistance can be improved, electric field dependency is small, resistance change due to environment can be reduced, and better uniform chargeability and transferability can be obtained. is there.

  For this reason, it is possible to prevent leakage discharge such as pinhole leak, which is thought to occur due to electric field concentration and dielectric breakdown due to the occurrence of large aggregates of carbon black as in the past, and also to prevent toner sticking. be able to. Further, charging unevenness due to resistance change or resistance variation, image quality defects due to leakage discharge, and fluctuations in image density due to environmental fluctuations are reduced, and high-quality images can be obtained over a long period of time. In addition, acidic carbon black does not require a coupling process for improving dispersibility, addition of insulating particles, metal oxides, and the like, and the manufacturing process is simplified.

  The pH of the acidic carbon black is not particularly limited as long as it is 5 or less as described above, but is preferably 4.5 or less, more preferably 4.0 or less. The pH of the acidic carbon black is defined as follows (details conform to JIS K6221-1982). The “pH” of acidic carbon black refers to the pH (logarithmic value of hydrogen ion concentration) measured for a muddy substance obtained by boiling carbon black with water and removing the supernatant after cooling. It is related to the amount of oxygen-containing functional groups on the carbon black surface (functional groups such as carboxylic acid, hydroxy acid, lactone, and quinoid), and it is thought that the lower the pH, the more acidic surface functional groups (the Carbon Black Association) Edited / published "Carbon Black Handbook" (1995)). In addition, there is a volatile matter as a physical property value representing the amount of the oxygen-containing functional group on the surface of carbon black. This volatile content is expressed as a percentage of the weight loss when carbon black is held in an atmosphere of 950 ± 25 ° C. for 7 minutes.

  Acidic carbon black can be produced by a contact method. Examples of the contact method include a channel method and a gas black method. Acidic carbon black can also be produced by a furnace black method using gas or oil as a raw material. If necessary, after these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH can be adjusted by subjecting it to the above-mentioned liquid phase acid treatment. For this reason, carbon black obtained by furnace method production and adjusted to have a pH of 5 or less by post-treatment can also be suitably used in the present invention.

  Specific examples of acidic carbon black include “Color Black FW200” (pH 2.5, volatile content 20%), “FW2” (pH 2.5, volatile content 16.5%), and “FW2V” manufactured by Degussa Japan. ”(PH 2.5, volatile matter 16.5%),“ Special Black 6 ”(pH 2.5, volatile matter 18%),“ 5 ”(pH 3, volatile matter 15%),“ 4 ”(pH 3, Volatile content 14%), "4A" (pH 3, volatile content 14%)), "Printex 150T" (pH 4, volatile content 10%), "Printex 140U" (pH 4.5, volatile content 5%), Cabot's “REGAL 400R” (pH 4.0, volatile content 3.5%), “MONARCH 1000” (pH 2.5, volatile content 9.5%), “MONARCH 1300” (pH 2.5, volatile content) 9.5%) Etc. The.

  Acidic carbon black may be blended alone in the resin composition constituting the conductive surface layer, but any two or more kinds of acidic carbon black may be blended to obtain mechanical strength, hardness, and elastic modulus. For example, it can be formulated so as to meet the requirements of the entire system. The compounding amount in the resin composition does not enter a suitable resistance region unless the concentration is higher than that of ordinary conductive carbon black, but is generally 5 to 40 parts by mass (the number of parts by mass with respect to 100 parts by mass of the resin composition). preferable. If the amount is less than 5 parts by mass, the resistance is too high and the desired resistance cannot be obtained. On the other hand, when the amount exceeds 40 parts by mass, the resistance is too low and image quality defects such as white spots may occur.

(Conductive roll layer structure)
The layer structure of the conductive rolls of the first to third inventions described above (hereinafter sometimes referred to as “the conductive roll of the invention”) is at least on the outer peripheral surface of the conductive support. There is no particular limitation as long as the base elastic layer including one or more conductive elastic layers and the conductive surface layer provided on the outer peripheral surface of the base elastic layer are provided in this order.
If a specific example is given, the layer structure as shown in FIG. 5 will be mentioned, for example. FIG. 5 is a schematic cross-sectional view showing an example of the conductive roll of the present invention.

  Hereinafter, an exemplary embodiment of the conductive roll of the present invention will be shown and described in detail with reference to FIG. As shown in FIG. 5, the conductive roll 100 as an exemplary embodiment of the present invention has a roll-shaped structure including at least a conductive support 10, a base elastic layer 20, and a conductive surface layer 30. Have. Thus, when the conductive roll 100 of the present invention has a roll shape, when used as a charging unit or a transfer unit, it is excellent in terms of maintaining the durability of a photoconductor or the like and uniform charging.

  The conductive support 10 is made of a metal such as SUS or SUM, for example. In the conductive roll 100 having a roll-like structure as shown in FIG. 4, the conductive support 10 is arranged so as to penetrate the axial direction of the conductive roll 100, and may function as a rotating shaft of the conductive member 100. Is possible. Although not shown, an external power source is connected to the conductive support 10 and a desired bias is applied, so that it also functions as a voltage application unit to the conductive roll 100 together with the external power source.

  The base elastic layer 20 is formed on the surface of the conductive support 10 and is made of a specific rubber composition containing the components (A) to (C) as described above. The surface characteristics (surface roughness, hardness, friction coefficient), electrical characteristics (electric resistance), etc. are adjusted. By appropriately adjusting various conditions such as electrical characteristics and surface characteristics of the base elastic layer 20, charging means, transfer means (including both primary and secondary transfer means in the intermediate transfer system), and Also, it can be suitably used as a static elimination means.

  The hardness of the base elastic layer 20 is preferably adjusted in the range of 10 ° to 70 °, more preferably in the range of 20 ° to 50 °, with the Asuka C hardness described in JISK-7312. When it exceeds 70 °, the roll hardness becomes high, and deformation due to the nip pressure at the nip portion is small, which may cause a problem that the nip cannot be stably formed. If it is less than 10 °, the roll hardness becomes soft, it becomes difficult to polish into a roll shape, and problems such as variations in the outer shape of the roll may occur.

  Although the thickness of the foundation | substrate elastic layer 20 is not specifically limited, 1-20 mm is preferable and 3-10 mm is more preferable. If the thickness of the base elastic layer 20 is less than 1 mm, there is a problem that the nip cannot be stably formed because deformation at the nip is small. Further, when the thickness of the base elastic layer 20 exceeds 20 mm, the outer diameter of the conductive roll is larger than 40 mm, so that there are cases where the M / C size increases and the cost increases. .

The conductive roll of the present invention is preferably prepared by coating and fixing a conductive resin tube as the surface conductive layer 30 on the outer peripheral surface of the base elastic layer 20. As the conductive resin tube, it is preferable that an electron conductive conductive agent is dispersed. Further, as the electron conductive conductive agent, oxidized carbon black is preferable.
Hereinafter, a method for coating and fixing the conductive resin tube on the outer peripheral surface of the base elastic layer 20 will be described in detail.

A method for covering and fixing the conductive resin tube to the outer peripheral surface of the base elastic layer 20 is not particularly limited, but fluid such as air is press-fitted into the inner peripheral surface of the conductive resin tube, and in this state Insert a roll (hereinafter sometimes referred to as a “base roll”) in which the base elastic layer 20 is formed on the conductive support on the inner peripheral side of the conductive resin tube, and then stop the press-fitting of the fluid. A method of inserting and fixing by contracting the conductive resin tube can be mentioned.
As another method, the diameter of the base roll is temporarily made smaller than the inner diameter of the conductive resin tube by cooling the base layer, and in this state, the base roll is placed on the inner peripheral surface of the conductive resin tube. It is possible to apply a method of press-fitting into

<Image forming apparatus>
Next, the image forming apparatus of the present invention will be described. The image forming apparatus of the present invention is an image forming apparatus that includes at least one conductive roll and forms an image using toner, and the conductive roll uses the conductive roll of the present invention described above. If it is a thing, it will not specifically limit. The use of the conductive roll of the present invention is not particularly limited, but it is preferably used as a transfer roll or a charging roll in the image forming apparatus, and more preferably used as a transfer roll.

In such a case, the image forming apparatus more preferably includes at least the conductive roll of the present invention and a cleaning device having a metal blade in contact with the surface of the conductive roll.
In particular, in order to ensure sufficient wear resistance even for cleaning using a metal blade, the outer peripheral surface of the conductive roll is made of a material having a surface microhardness of 18 or more such as polyimide resin. Is preferred.
Further, by applying a metal blade as the cleaning device, the spherical toner attached to the surface of the conductive roll can be effectively cleaned even when spherical toner is used as the toner.

However, the spherical toner means that the shape factor SF is 100 to 140 (preferably 100 to 130), and the shape factor SF is a factor defined by the following formula (1). It is.
Formula (1)
SF =
[(Maximum length of toner particles) ² / (projected area of toner particles)] × π × (1/4) × 100
The absolute maximum length of the toner particles and the projected area of the toner particles are measured using a video camera with an optical microscope image of the toner dispersed on the slide glass using a Luzex image analyzer (manufactured by Nireco Corporation, FT). It was carried out by taking in a Luzex image analyzer and processing the image.

The other parts of the image forming apparatus of the present invention as described above can be configured by arbitrarily combining other known apparatuses. At least the charging device for uniformly charging the surface of the image carrier and the surface thereof. An electrostatic latent image forming apparatus that forms an electrostatic latent image according to image information on an image carrier pair that is uniformly charged, and a toner image obtained by using toner to form the electrostatic latent image formed on the image carrier pair. And a transfer device that temporarily transfers the toner image formed on the image carrier to an intermediate transfer member, and further transfers the toner image on the intermediate transfer pair to a recording medium. In this case, the conductive roll of the present invention can be used as a transfer roll used in the transfer device or a charging roll that comes into contact with the image carrier, and comes into contact with the surface of the conductive roll. Metal brace May be arranged.

Hereinafter, the case where the electroconductive roll of the present invention is used as a transfer roll will be described for the image forming apparatus of the present invention. However, the image forming apparatus of the present invention is not limited to the configuration described below. The image forming apparatus of the present invention will be described below with reference to the drawings.
FIG. 6 is a schematic view showing an example of the image forming apparatus of the present invention, in which 1 is a photosensitive drum (image carrier), 2 is an intermediate transfer belt (intermediate transfer body), and 3 is a bias roll (second transfer means). ) 4 is a paper tray, 5 is a black developer, 6 is a yellow developer, 7 is a magenta developer, 8 is a cyan developer, 9 is an intermediate transfer body cleaner, 13 is a peeling claw, 21 is a belt roll, and 22 is A backup roll, 23 is a belt roll, 24 is a belt roll, 25 is a transfer roll (first transfer means), 26 is an electrode roll, 31 is a cleaning blade, 41 is paper, 42 is a pickup roll, and 43 is a feed roll.

  Next, the configuration of the image forming apparatus shown in FIG. 6 will be described. Around the photosensitive drum 1, a black developing unit 5, a yellow developing unit 6, a magenta developing unit 7, and a cyan developing unit 8 are arranged in this order along the arrow A direction. A transfer roll 25 (conductive roll of the present invention) is sandwiched between the photosensitive drum 1 and the intermediate transfer belt 2 on the side opposite to the side where the four color developing devices are disposed. It is arranged so as to be in pressure contact with.

  The intermediate transfer belt 2 is stretched by a conductive roll 25, a belt roll 21, a belt roll 23, a backup roll 22, and a belt roll 24 that are sequentially arranged in the direction of arrow B in contact with the inner peripheral surface thereof. An intermediate transfer body cleaner 9 is disposed on the opposite side of the belt roll 24 with the belt 2 interposed therebetween. Further, the peeling claw 13 is disposed so as to contact the outer peripheral surface of the portion of the intermediate transfer belt 2 stretched between the backup roll 22 and the belt roll 24.

  The backup roll 22 is in pressure contact with the bias roll 3 via the intermediate transfer belt 2, and the paper 41 can be inserted between the backup roll 22 (the intermediate transfer belt 2 pressed against) and the bias roll 3. is there. A cleaning blade 31 is provided around the bias roll 3 so as to be in contact with this surface. In addition, an electrode roll 26 is disposed in contact with the backup roll 22 on a substantially opposite side of the backup roll 22 on which the bias roll 3 is disposed.

  In the direction in which the paper 41 passes between the backup roll 22 and the bias roll 3, a pair of feed rolls 43 that are in contact with each other are disposed, and the paper 41 can be inserted between the two feed rolls 43. Further, on the opposite side of the pair of feed rolls 43 from the side where the backup roll 22 and the bias roll 3 are provided, the paper tray 4 storing the paper 41 and the paper 41 from the paper tray 4 are fed to the pair of feed rolls 43. A pickup roll to be supplied to the contact portion is disposed.

Next, image formation using the image forming apparatus shown in FIG. 6 will be described. First, the photosensitive drum 1 rotates in the direction of arrow A, and the surface thereof is uniformly charged by a charging device (not shown). An electrostatic latent image of the first color (for example, Bk) is formed on the charged photosensitive drum 1 by image writing means (not shown) such as a laser writing device.
The electrostatic latent image is developed with toner by the black developing device 5 to form a visualized toner image T. The toner image T reaches the primary transfer portion where the transfer roll 25 (first transfer means) is disposed by the rotation of the photosensitive drum 1, and an electric field having a reverse polarity is applied to the toner image T from the transfer roll 25. The toner image T is primarily transferred by the rotation of the intermediate transfer belt 2 in the direction of arrow B while being electrostatically attracted to the outer peripheral surface of the intermediate transfer belt 2.

Thereafter, similarly, a second color toner image, a third color toner image, and a fourth color toner image are sequentially formed so that each color toner image corresponds to image information on the outer peripheral surface of the intermediate transfer belt 2. Overlapping is performed to form a multiple toner image. The multiple toner image transferred to the intermediate transfer belt 2 reaches the secondary transfer portion where the bias roll 3 (second transfer means) is installed by the rotation of the intermediate transfer belt 2.
The secondary transfer portion is disposed so as to face the bias roll 3 from the inner peripheral surface side of the intermediate transfer belt 2 and the bias roll 3 disposed in contact with the outer peripheral surface side of the intermediate transfer belt 2 that carries the toner image. The backup roll 22 and an electrode roll 26 that rotates in pressure contact with the backup roll 22.

The recording paper 41 is taken out one by one from the recording paper bundle accommodated in the paper tray 4 by the pickup roll 42, and is passed through the feed roll 43 to a pressure contact portion between the intermediate transfer belt 2 and the bias roll 3 of the secondary transfer portion. It is fed at the timing of
The multi-toner image carried on the outer peripheral surface of the intermediate transfer belt 2 is transferred to the fed recording paper 41 by the pressure contact conveyance by the bias roll 3 and the backup roll 22 and the rotation of the intermediate transfer belt 2.

  The recording paper 41 onto which the multiple toner image has been transferred is peeled off from the intermediate transfer belt 2 by operating the peeling claw 13 at the retracted position until the end of the secondary transfer of the final toner image, and conveyed to a fixing device (not shown). Next, the recording paper 41 is pressed / heated by a fixing device, whereby a multiple toner image is fixed on the surface thereof to form an image. The intermediate transfer belt 2 that has completed the transfer of the multiple toner images to the recording paper 41 is subjected to removal of residual toner by an intermediate transfer body cleaner 9 provided downstream of the secondary transfer portion, and is ready for the next transfer. The transfer roll 3 is attached so that a cleaning blade 31 made of metal is always in contact therewith, and foreign matters such as toner particles and paper dust adhered by transfer are removed.

In the case of transfer of a single color image, the primary transferred toner image T is immediately secondarily transferred and conveyed to the fixing device. In the case of transfer of a multicolor image by superimposing a plurality of colors, the toner image of each color is transferred to the primary transfer unit. Therefore, the rotation of the intermediate transfer belt 2 and the photosensitive drum 1 is synchronized so that the toner images of the respective colors do not shift so as to match exactly.
In the secondary transfer section, an output pressure (transfer voltage) having the same polarity as the polarity of the toner image is applied to an electrode roll 26 that is in pressure contact with a backup roll 22 that is disposed so as to face the transfer roll 3 and the intermediate transfer belt 2. Then, the toner image is transferred to the recording paper 41 by electrostatic repulsion.

  FIG. 7 is a schematic view showing another example of the image forming apparatus of the present invention. In FIG. 7, the image forming apparatus includes an image carrier 101, a charger 102, an electrostatic latent image forming writing device 103, black (K), yellow (Y), magenta (M), and cyan (C). Developing devices 104 a, 104 b, 104 c, 104 d containing the developer, a neutralizing lamp 105, a cleaning device 106, an intermediate transfer body 107, and a transfer roll 108 which is a semiconductive roll of the present invention.

Around the image carrier 101, a non-contact charger 102 that uniformly charges the surface of the image carrier 101 in order along the rotation direction (arrow A direction) of the image carrier 101, and an arrow corresponding to image information A writing device 103 that forms an electrostatic latent image on the surface of the image carrier 101 by irradiating the surface of the image carrier 101 with scanning exposure indicated by L, and a developer that supplies toner of each color to the electrostatic latent image 104a, 104b, 104c, 104d, a drum-shaped intermediate transfer member 107 that contacts the surface of the image carrier 101 and can be driven to rotate in the direction of arrow B as the image carrier 101 rotates in the direction of arrow A; A neutralizing lamp 105 that neutralizes the surface of the 101 and a cleaning device 106 that contacts the surface of the image carrier 101 are disposed. The intermediate transfer member 107 may be an endless belt.
In addition, a transfer roll (conductive roll of the present invention) 108 capable of controlling contact / non-contact with the surface of the intermediate transfer body 107 is disposed on the opposite side of the image transfer body 101 with respect to the intermediate transfer body 107. At the time of contact, the transfer roll 108 can be driven to rotate in the direction of arrow C as the intermediate transfer member 107 rotates in the direction of arrow B.

Next, image formation using the image forming apparatus shown in FIG. 7 will be described. First, as the image carrier 101 rotates in the direction of arrow A ′, the surface of the image carrier 101 is uniformly charged by the non-contact type charger 102 and is uniformly charged by the writing device 103. An electrostatic latent image corresponding to the image information of each color is formed on the surface, and the developing devices 104a, 104b, and the like are formed on the surface of the image carrier 101 on which the electrostatic latent image is formed according to the color information of the electrostatic latent image. A toner image is formed by supplying toner from 104c and 104d.
Next, the toner image formed on the surface of the image carrier 101 is applied with a voltage between the image carrier 101 and the intermediate transfer member 107 by a power source (not shown), whereby the image transfer member 101 and the intermediate transfer member are transferred. The image is transferred to the surface of the intermediate transfer body 107 at the contact portion with the body 107.
The surface of the image carrier 101 on which the toner image is transferred to the transfer body 107 is neutralized by irradiating light from the neutralization lamp 108, and the toner remaining on the surface is removed by a cleaning device 106 cleaning blade. .

By repeating the above process for each color, a toner image of each color is laminated on the surface of the intermediate transfer member 107 so as to correspond to the image information.
It should be noted that the transfer roll 108 is not in contact with the intermediate transfer member 107 during the above-described process, and the toner image of all colors is laminated on the surface of the intermediate transfer member 107 and then applied to the recording medium 109. It abuts during transfer.

  The toner images laminated and formed on the surface of the intermediate transfer member 107 in this way are rotated with the intermediate transfer member 107 and the transfer roll along with the rotation of the intermediate transfer member 107 in the arrow B ′ direction (and the rotation in the transfer roll 108C direction). It moves to a contact part (nip part) with 108. At this time, the recording medium 109 is inserted through the nip portion in the direction of arrow N by a paper transport roll (not shown), and is applied to the surface of the intermediate transfer body 107 by a voltage applied between the intermediate transfer body 107 and the transfer roll 108. The laminated toner images are collectively transferred to the surface of the recording medium 109 at the nip portion.

  The recording medium 109 on which the toner image is formed is conveyed to a fixing device (not shown), and an image is formed by fixing the toner image on the surface of the recording medium 109 by the fixing device.

  In the above image formation, the conductive roll of the present invention is used as the transfer roll 25 in the image forming apparatus shown in FIG. 7 and the transfer roll 108 in the image forming apparatus shown in FIG. It is excellent in transferability, and density unevenness of the obtained image can be reduced.

  Furthermore, as described above, when the conductive roll of the present invention is incorporated and used as a charging roll or transfer roll in an image forming apparatus, it is preferable to use a spherical toner as the toner. By using spherical toner as the toner, the material constituting the transfer surface has a low surface hardness and a high volume resistance, thereby obtaining a high-quality transfer image quality free from image quality defects (holocharacter, blur, color registration). be able to.

  The spherical toner contains at least a binder resin and a colorant. The spherical toner may preferably use 2 to 12 μm particles, more preferably 3 to 9 μm particles.

  Examples of the binder resin include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, Homopolymers and copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified. Particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. A polymer, polyethylene, polypropylene, etc. are mentioned. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned.

  Examples of the colorant include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp. Black, Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is a typical example.

  The spherical toner may be subjected to internal addition treatment or external addition treatment with a known additive such as a charge control agent, a release agent, and other inorganic fine particles. Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  As the charge control agent, known ones can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.

As the other inorganic fine particles, small-sized inorganic fine particles having an average primary particle size of 40 nm or less are used for the purpose of powder flowability, charge control, etc. Inorganic or organic fine particles having a diameter may be used in combination. As these other inorganic fine particles, known ones can be used. Examples thereof include silica, alumina, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate.
In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

  The spherical toner is not particularly limited by the production method, and can be obtained by a known method. Specifically, for example, a kneading and pulverizing method in which a binder resin and a colorant and, if necessary, a release agent and a charge control agent are kneaded, pulverized and classified, and particles obtained by the kneading and pulverizing method are mechanically impacted. Method of changing shape by force or heat energy, emulsion polymerization of binder resin polymerizable monomer, dispersion of formed dispersion, colorant, release agent and charge control agent as required Liquid emulsion, agglomeration, heat fusion to obtain spherical toner, emulsion polymerization aggregation method, polymerizable monomer for obtaining binder resin, colorant, release agent if necessary, charge control agent A suspension polymerization method in which a solution such as a suspension is polymerized by suspending in an aqueous solvent, a binder resin and a colorant, and a release agent and a charge control agent as necessary are suspended in an aqueous solvent and granulated. Examples thereof include a dissolution suspension method. In addition, a manufacturing method may be performed in which the spherical toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure. When the external additive is added, it can be produced by mixing the spherical toner and the external additive with a Henschel mixer or a V blender. In addition, when the spherical toner is manufactured by a wet method, it can be externally added by a wet method.

The present invention will be specifically described by the following examples, but the present invention is not limited thereto.
<Example 1>
(Formation of base elastic layer)
First, a stainless steel core shaft (φ12 mm) was used as a conductive support, and this outer periphery was covered with a single base elastic layer (conductive elastic layer) previously formed into a hollow shape (hereinafter referred to as a base elastic layer). And a roll made of a conductive support is abbreviated as “underlying roll”).

  Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3103, ethylene oxide content: 35 mol%) 70 parts by mass, acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., Nipol DN-219, acrylonitrile content: 33. 5 parts by mass) 30 parts by mass and 10 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) as an electron conductive agent, and Asahi Thermal FT (Asahi Carbon Co., Ltd., DBP oil absorption: 28 ml / 100 g) is used in combination with 20 parts by mass. Further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Noxera-M, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) 1.5 parts by mass and, as a blowing agent, benzenesulfonyl hydrazide And 6 parts by weight, and the mixture was kneaded with an open roll. The kneaded mixture (rubber composition) was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

  For the obtained base roll, (1) volume resistance value of the base elastic layer only (22 ° C. 55RH%, Rv1), (2) volume fluctuation range of the volume resistance value (Rv1) of the base elastic layer only (low temperature and low humidity environment ( 10 ° C 15RH%) and high temperature and high humidity environment (28 ° C 85RH%) difference in common logarithm of resistance value), (3) 25 hours continuous energization test using only the base elastic layer (under 10 ° C 15% RH environment) And (4) roll hardness (Asuka C) of only the base elastic layer was measured. The results are shown in Table 1.

(Formation of conductive surface layer)
Next, a conductive resin tube was prepared as follows as a conductive surface layer. This conductive resin tube has a volume resistance value (Ω) of acid carbon black (Degussa Japan Co., Ltd./Special Black 4; pH 3.5) to polyimide U varnish A for heat-resistant film manufactured by Ube Industries, Ltd. A coating liquid whose concentration is adjusted by dispersing so that the common logarithmic value is 6.5 is applied to the outside of a cylindrical mold and produced in a tube shape.

(Preparation of conductive roll)
Next, a conductive roll of Example 1 was obtained by inserting and fixing a base roll (conductive support and base elastic layer) on the inner peripheral side of the conductive resin tube (conductive surface layer).
In addition, as an insertion method, it is in a state in which a fluid such as air is injected into a conductive resin tube that has been processed into a predetermined shape in advance, and the core metal tip of the base roll is inserted into the conductive resin tube, The ground roll was inserted into the conductive resin tube together with the fluid to obtain the conductive roll of Example 1 having the same configuration as shown in FIG.

About the obtained conductive roll, (5) volume resistivity (Rv3) of the conductive surface layer, (6) surface resistivity (ρs2) of the conductive surface layer, (7) thickness of the conductive surface layer, (8) Volume resistance value (Rv2) of conductive roll, (9) Environmental fluctuation range of volume resistance value of conductive roll (low temperature and low humidity environment (10 ° C 15RH%) and high temperature and high humidity environment (28 ° C 85RH%) Difference in common logarithm of resistance value), (10) Roll hardness of conductive roll (Asuka C), (11) In-plane resistance variation of conductive roll surface (difference between common logarithm of maximum value and minimum value) (12) 25-hour continuous energization test of conductive roll (change in volume resistance value by applying a current of 20 μA for 25 hours in an environment of 10 ° C. and 15% RH), (13) initial cleaning property, (14) Cleaning performance after running equivalent to 30 KPV, ( 15) Transferability (transfer latitude), (16) Density unevenness of transfer image quality was evaluated. The results are shown in Table 1.
Each of the evaluation methods described above will be described in detail below except for those described above.

-(5) Volume resistance value of conductive surface layer (Rv3)-
Using the circular electrode shown in FIG. 4, a conductive surface layer is sandwiched as a sample S between the cylindrical electrode portion C and the second voltage application electrode B in the first voltage application electrode A, and the first voltage application electrode A The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C and the second voltage application electrode B is measured, and the volume resistance value of the conductive surface layer ( The volume resistivity ρv (Ωcm) of Rv3) can be calculated. Here, in the following formula, t represents the thickness of the sample S.
Formula ρv = πd ² / 4t × (V / I)

-(11) In-plane resistance variation on the surface of the conductive roll-
For the in-plane resistance variation on the surface of the conductive roll, the resistance measuring device shown in FIG. 8 was used. FIG. 8 is a schematic perspective view of a resistance measuring device for measuring in-plane resistance variation on the surface of the conductive roll. In FIG. 7, the outer peripheral surface of the conductive roll 401 having the shaft 401 as the central axis is in pressure contact with the ring-shaped electrode 402, and the electrode 402 can be driven to rotate as the conductive roll 401 rotates. An ammeter and a voltmeter are connected in series between the electrode 402 and the shaft 401.
The measurement is performed by measuring the roll resistance in the circumferential direction by rotating the conductive roll 400 while the ring-shaped electrode 402 is in pressure contact with the outer peripheral surface of the conductive roll 400, and the electrode 402 is connected to the conductive roll 400. Roll resistance in the axial direction can be performed by moving in the axial direction.

In actual measurement, the conductive roll and the electrode (width 3.5 mm, outer diameter 10 mm) were pressed against each other with a load of 50 g while rotating the conductive roll at 30 rpm. The current value (I) is read while applying a voltage of 500 V (V) between the shaft and the electrode, and the resistance value (R) at each point on the surface of the conductive roll is obtained from the relationship of R = V / I. It was.
In the measurement, the conductive roll is divided into 60 parts in the circumferential direction and 10 parts in the axial direction to obtain a resistance value of a total of 600 points on the surface of the conductive roll, and the maximum value and the minimum value of these 600 points are calculated. The difference in common logarithm value was defined as the in-plane resistance variation on the surface of the conductive roll.

-(13) and (14) Evaluation of cleaning property-
The cleaning property evaluation was performed using a unit in which a metal blade (SUS304, thickness: 0.1 mm) was applied to the surface of the conductive roll at an angle of 25 ° and a biting amount of 0.6 mm. This unit is attached to an image forming apparatus using toner having a shape factor SF of 125 and a volume average particle diameter of 5.5 μm, and (13) initial cleaning and (14) 30K image samples are output. The property was visually evaluated according to the following criteria.
○: There is no problem in cleaning properties.
X: There is a problem in cleaning properties.

― (15) Transferability―
The transferability was evaluated by performing image formation using an image forming apparatus having the structure shown in FIG. The obtained conductive roll was used as the transfer roll 25 of the image forming apparatus shown in FIG. 6, and toner having a shape factor (SF) of 125 and a volume average particle diameter of 5.5 μm was used. The evaluation of transferability was carried out in both a high temperature and high humidity environment (28 ° C. and 85 RH%) and a low temperature and low humidity environment (10 ° C. and 15 RH%).
The evaluation of transferability is made up of a transfer current (lower limit current value) at which transferability of PK color (process black) is obtained, and a transfer current (upper limit current value) that causes no problem in K color (black) retransfer. When the range was 2 μA or more, it was determined that there was transferability. The evaluation index is as follows.
○: In a high temperature and high humidity environment and a low temperature and low humidity environment, the transfer current range is 2 μA or more.
X: In a high-temperature and high-humidity environment and / or a low-temperature and low-humidity environment, the transfer current range is less than 2 μA.

-(16) Density unevenness of transfer image quality-
The transfer image quality was evaluated by forming an image using an image forming apparatus having the structure shown in FIG. The obtained conductive roll was used as the transfer roll 25 of the image forming apparatus having the structure shown in FIG. 6, and the toner used was a spherical toner having a shape factor (SF) of 125 and a volume average particle diameter of 5.5 μm. . Further, the evaluation of the transfer image quality was carried out in both a high temperature and high humidity environment (28 ° C., 85 RH%) and a low temperature and low humidity environment (10 ° C., 15 RH%).
The evaluation of the transfer image quality was determined by the density unevenness of the image quality of 30% PK color. The evaluation index is as follows.
○: Uneven image quality in high temperature and high humidity environment and low temperature and low humidity environment ×: Uneven image quality in high temperature and high humidity environment and / or low temperature and low humidity environment

<Example 2>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3103, ethylene oxide content: 35 mol%) 70 parts by mass, acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., Nipol DN-219, acrylonitrile content: 33. 5 parts by mass) 30 parts by mass, and 11 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) and Asahi Thermal MT (Asahi Carbon Co., Ltd., DBP oil absorption: 35 ml / 100 g) is used in combination with 25 parts by mass. Further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Noxera-M, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) 1.5 parts by mass and, as a blowing agent, benzenesulfonyl hydrazide And 6 parts by weight, and the mixture was kneaded with an open roll. The kneaded mixture was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

(Formation of conductive surface layer)
Next, a conductive resin tube was prepared as follows as a conductive surface layer. This conductive resin tube has a volume resistance value (Ω) of acid carbon black (manufactured by Degussa Japan Co., Ltd./Printex 140U: pH 4.5) to polyimide U varnish A for heat-resistant film manufactured by Ube Industries, Ltd. A coating liquid whose concentration is adjusted by dispersing so that the common logarithmic value is 6.0 is applied to the outside of a cylindrical mold and produced in a tube shape. The film thickness of the obtained conductive resin tube was 40 μm, and the surface resistivity was 1 × 10 ¹¹ Ω / □.

(Preparation of conductive roll)
Next, the conductive roll of Example 2 was obtained by inserting and fixing the base roll on the inner peripheral side of the conductive resin tube in the same manner as in Example 1. The roll hardness of this conductive roll was 68 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 7.5 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 3>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3103, ethylene oxide content: 35 mol%) and 50 parts by mass of acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., Nipol DN-219, acrylonitrile triro content: 33.5) (Mass%) 50 parts by mass and 10 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) as an electron conductive conductive agent, and Asahi Thermal MT (Asahi Carbon Co., Ltd., DBP oil absorption: 35 ml / 100 g) is used in combination with 25 parts by mass. Further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Nouchira-M, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts by mass and, as a blowing agent, benzenesulfonyl hydrazide 6 And amount unit, and the mixture was kneaded with an open roll. The kneaded mixture (rubber composition) was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

  Next, using the same conductive resin tube as in Example 1, a conductive roll of Example 3 is obtained by inserting and fixing a base roll on the inner peripheral side of the conductive resin tube in the same manner as in Example 1. It was. The roll hardness of this conductive roll was 64 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.2 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 4>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3103, ethylene oxide content: 35 mol%) and 50 parts by mass of acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., Nipol DN-219, acrylonitrile triro content: 33.5) (Mass%) 50 parts by mass and 10 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) as an electron conductive conductive agent, and Asahi Thermal MT (Asahi Carbon Co., Ltd., DBP oil absorption: 35 ml / 100 g) is used in combination with 30 parts by mass. Further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Nouchira-M, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts by mass and, as a blowing agent, benzenesulfonyl hydrazide 6 And amount unit, and the mixture was kneaded with an open roll. The kneaded mixture was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a base roll having an outer diameter of 20 mm was obtained.

  Next, using the same conductive resin tube as in Example 1, a conductive roll of Example 4 is obtained by inserting and fixing a base roll on the inner peripheral side of the conductive resin tube in the same manner as in Example 1. It was. The roll hardness of this conductive roll was 68 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.3 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 5>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3103, ethylene oxide content: 35 mol%) and 50 parts by mass, and acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., DN401, acrylonitrile content: 18 mass%) ) 50 parts by mass, and 7 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) and Asahi Thermal MT (Asahi Carbon) Co., Ltd., DBP oil absorption: 35 ml / 100 g) 65 parts by mass, and further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Ouchi) 1.5 parts by mass of Shinsei Chemical Industries, Noxera-M), and 6 parts by mass of benzenesulfonyl hydrazide as a foaming agent When, the mixture was kneaded with an open roll. The kneaded mixture was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

  Next, using the same conductive resin tube as in Example 2, the conductive roll of Example 5 is obtained by inserting and fixing the base roll on the inner peripheral side of the conductive resin tube as in Example 1. It was. The roll hardness of this conductive roll was 70 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.1 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 6>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, 70 parts by mass of epichlorohydrin rubber (Daiso Co., Ltd., CG-105, ethylene oxide content: 38 mol%) and acrylonitrile butadiene rubber (Nippon Zeon Co., Ltd., DN219, acrylonitrile content: 33.5) (Mass%) 30 parts by mass and 10 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) as an electron conductive conductive agent, and Asahi Thermal FT ( Asahi Carbon Co., Ltd., DBP oil absorption: 28 ml / 100 g) 35 parts by mass is used in combination, and as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator ( 1.5 parts by mass of Nouchira-M) manufactured by Ouchi Shinsei Chemical Co., Ltd. and 6 parts by mass of benzenesulfonyl hydrazide as a foaming agent For example, the mixture was kneaded with an open roll. The kneaded mixture (rubber composition) was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

  Next, using the same conductive resin tube as in Example 2, the conductive roll of Example 6 is obtained by inserting and fixing the base roll on the inner peripheral side of the conductive resin tube in the same manner as in Example 1. It was. The roll hardness of this conductive roll was 67 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.5 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 7>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3105, ethylene oxide content: 38 mol%) 50 parts by mass, and acrylonitrile butadiene rubber (manufactured by JSR Corporation, N260S, acrylonitrile content: 22 mass%) 50 11 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) and Asahi Thermal MT (Asahi Carbon Co., Ltd.) ), DBP oil absorption: 35 ml / 100 g) 38 parts by mass, and further, as a vulcanizing agent, 1 part by mass of sulfur (manufactured by Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Ouchi Shinsei Chemical) 1.5 parts by mass of Noxera-M manufactured by Kogyo Co., Ltd. and 6 parts by mass of benzenesulfonyl hydrazide as a foaming agent And the mixture was kneaded with an open roll. The kneaded mixture was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

(Formation of conductive surface layer) / (Preparation of conductive roll)
Next, using the same conductive resin tube as in Example 2, the conductive roll of Example 7 is obtained by inserting and fixing the base roll on the inner peripheral side of the conductive resin tube as in Example 1. It was. The roll hardness of this conductive roll was 68 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.1 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Example 8>
A stainless steel core shaft (φ12 mm) was used as the conductive support, and this outer periphery was covered with a single base elastic layer (conductive foam layer) that had been previously formed into a hollow shape.
Specifically, epichlorohydrin rubber (manufactured by Nippon Zeon Co., Ltd., Gechron 3105, ethylene oxide content: 38 mol%) and 70 parts by mass, and acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd., DN202H, acrylonitrile toluene content: 31 mass%) 30 parts by mass, and 10 parts by mass of granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption: 288 ml / 100 g) and Asahi Thermal MT (Asahi Carbon) Co., Ltd., DBP oil absorption: 35 ml / 100 g) 22 parts by mass, and further as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Co., Ltd., 200 mesh) and a vulcanization accelerator (Ouchi) Shinsei Kagaku Kogyo Co., Ltd., Noxera-M) 1.5 parts by mass and, as a blowing agent, benzenesulfonyl hydrazide 6 And amount unit, and the mixture was kneaded with an open roll. The kneaded mixture (rubber composition) was wound around a core shaft, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and a roll-shaped base roll having an outer diameter of 20 mm was obtained.

  Next, using the same conductive resin tube as in Example 2, a conductive roll of Example 7 is obtained by inserting and fixing a base roll on the inner peripheral side of the conductive resin tube as in Example 1. It was. The roll hardness of this conductive roll was 64 by Asuka C, and the volume resistance value (Ω) of this conductive roll was 8.2 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Comparative Example 1>
The same conductive resin tube as in Example 1 was used as the conductive surface layer, and a urethane rubber sponge roll added with an ionic conductive agent (perchlorate) was used as the base elastic layer in the same manner as in Example 1. The electroconductive roll of the comparative example 1 was produced.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Comparative example 2>
A conductive roll of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the following conductive resin tube was used as the conductive resin tube constituting the conductive surface layer.
The conductive resin tube used was granular acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd .: oil absorption 288 ml / 100 g) as the carbon black, and the volume resistance value (Ω) was adjusted to 6.5 using the common logarithm value. A conductive nylon tube having a film thickness of 100 μm and a surface resistivity of 3 × 10 ⁶ Ω / □ was used.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Comparative Example 3>
The conductive roll of Comparative Example 3 was produced in the same manner as in Example 1 except that the materials constituting the conductive surface layer and the base elastic layer were changed.
In addition, the conductive resin tube which comprises a conductive surface layer used the conductive olefin type tube which used granular acetylene black (The Denki Kagaku Kogyo Co., Ltd. product: oil absorption amount 288 ml / 100g) as carbon black. The volume resistance value (Ω) of this conductive olefin-based tube is adjusted to 10 as a common logarithmic value, the film thickness is 100 μm, and the surface resistivity is 3 × 10 ¹⁰ Ω / □.

  In addition, as the base elastic layer, NBR polymer (N230SV manufactured by Nippon Synthetic Rubber Co., Ltd.) 100 parts by mass, pH 7.5 carbon black (Asahi Thermal FT manufactured by Asahi Carbon Co., Ltd.) 28 parts by mass, sulfur (manufactured by Tsurumi Chemical Co., Ltd. 200) 1 part by weight of mesh), 1 part by weight of a vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd. Noxeller CZ) was wound around a core metal of φ10 mm, and press vulcanized at 170 ° C. for 15 minutes. A molded product having a thickness of 5 mm was used. The volume resistance value (Ω) was 8.0 as a common logarithmic value.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Comparative example 4>
A conductive roll of Comparative Example 4 was produced in the same manner as Comparative Example 1 except for the conductive resin tube constituting the conductive surface layer.
In addition, as an electroconductive resin tube, peryostat 6321 (trade name) manufactured by Sanyo Kasei Kogyo Co., Ltd., which is a block type polymer having a polyether as a main segment, as an ion conductive polymer in 100 parts by mass of PVDF resin, The volume resistance value (Ω) was adjusted to 8 using a common logarithmic value, and the thickness was 0.15 mm and the surface resistivity was 1 × 10 ⁹ Ω / □.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

<Comparative Example 5>
The same conductive resin tube as that of Example 1 was used as the conductive surface layer, and 70 parts by mass of epichlorohydrin rubber (manufactured by Zeon Corporation, Gechron 3103, ethylene oxide content: 35 mol%) as the base elastic layer, and acrylonitrile butadiene rubber ( 30 parts by mass of Nippon Zeon Co., Ltd., Nipol DN-219, acrylonitrile content: 33.5% by mass) are mixed with Ketjen Black (manufactured by Lion Aguso Co., Ltd .: 360 ml) as an electron conductive agent. / 100g) 4.5 parts by mass, and further, as a vulcanizing agent, 1 part by mass of sulfur (Tsurumi Chemical Industry Co., Ltd., 200 mesh) and a vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd., Noxera-M) 1 0.5 parts by mass and 6 parts by mass of benzenesulfonyl hydrazide as a foaming agent were added and kneaded with an open roll. The kneaded mixture (rubber composition) is wound around the same core shaft as in Example 1, press vulcanized and foamed at 160 ° C. for 20 minutes to form a 4 mm-thick base elastic layer, and has a roll shape with an outer diameter of 20 mm. A ground roll was produced. Further, a conductive roll was produced in the same manner as in Example 1.

(Evaluation)
About the obtained foundation | substrate roll and electroconductive roll, the measurement and evaluation similar to Example 1 were implemented by the method similar to Example 1. FIG. The results are shown in Table 1.

As can be seen from Table 1, Examples 1 to 8 are excellent in transferability and transfer image quality in both a high temperature and high humidity environment and a low temperature and low humidity environment, and in-plane resistance variation is also good at 0.5 or less. It can be seen that the variation in resistance value due to environmental fluctuation is small, and that the resistance variation on the surface of the conductive roll is suppressed.
In addition, the cleaning performance after the continuous energization test, the initial stage and after running equivalent to 30 kpv was also good.

On the other hand, Comparative Examples 1 to 3 and 5 are inferior in transferability and transfer image quality in a high-temperature and high-humidity environment and / or low-temperature and low-humidity environment. In Comparative Example 4, high-temperature and high-humidity environment and / or low-temperature and low-humidity Transferability in the environment was poor. That is, it can be seen that the conductive rolls of Comparative Examples 1 to 5 have a large variation in resistance value due to environmental variation.
Further, it can be seen that Comparative Examples 2 and 3 have a large in-plane resistance variation of 1.2, and the resistance variation on the surface of the conductive roll is not suppressed. It turns out that the comparative example 5 has too high volume resistance value as an electroconductive roll.

  Further, Comparative Examples 2 to 4 were inferior in the cleaning properties after the initial run and after running corresponding to 30 kpv, and the resistance change due to energization was large.

It is a schematic diagram which shows the measuring method of the volume resistance value of a base elastic layer. It is the schematic cross section shown about the method of measuring the voltage change at the time of carrying out continuous electricity supply to a base elastic layer. It is a schematic diagram which shows the measuring method of the volume resistance value of an electroconductive roll. It is the schematic plan view (a) and schematic sectional drawing (b) which show an example of a circular electrode. It is a schematic cross section which shows an example of the electroconductive roll of this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows the other example of the image forming apparatus of this invention. It is a schematic perspective view of the resistance measuring apparatus for measuring the in-plane resistance variation of the surface of a conductive roll.

Explanation of symbols

1 ... photosensitive drum (image carrier),
2 ... Intermediate transfer belt (intermediate transfer member),
3. Bias roll (second transfer means),
4 ... paper tray,
5 ... Black developer,
6 ... Yellow developer,
7: Magenta developer,
8 ... Cyan developer,
9: Intermediate transfer member cleaner,
10 ... conductive support,
13 ... peeling nails,
20: Underlying elastic layer,
21 ... belt roll,
22 ... backup roll,
23 ... belt roll,
24 ... belt roll,
25 ... transfer roll (first transfer means),
26 ... Electrode roll,
30 ... conductive surface layer,
31 ... Cleaning blade,
40 ... metal plate,
41 ... paper,
42 ... Pickup roll,
43 ... feed roll,
100, 100 '... a roller-like conductive member,
101 ... Image carrier,
102 ... Charger,
103... Writing device,
104a, 104b, 104c, 104d ... developer,
106 ... Cleaning device,
107 ... intermediate transfer member,
108 ... transfer roll,
109 ... Recording medium,
400 ... conductive roll,
401 ... shaft,
402 ... Electrode,
500 ... conductive roll,
502 ... Metal roll,

Claims (4)

A conductive material in which at least a base elastic layer including at least one conductive elastic layer and a conductive surface layer provided on the outer peripheral surface of the base elastic layer are provided on the outer peripheral surface of the conductive support in this order. A sex roll,
The base elastic layer satisfies the following conditions (1) to (3).
(1) The volume resistance value (Rv1) in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(2) The difference in the common logarithm of the volume resistance value (Rv1) between 28 ° C. and 85% RH and 10 ° C. and 15% RH is 0.5 or less.
(3) The amount of change in the volume resistance value (Rv1) when a current of 20 μA is continuously applied for 25 hours in an environment of 10 ° C. and 15% RH is 0.5 or less as a common logarithmic value. A conductive material in which at least a base elastic layer including at least one conductive elastic layer and a conductive surface layer provided on the outer peripheral surface of the base elastic layer are provided on the outer peripheral surface of the conductive support in this order. A sex roll,
The base elastic layer has the following components (A) to (C) as essential components, and the component (C) is 5 to 80 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). A conductive roll characterized in that it is formed of a rubber composition contained in a mass part range.
(A) Epichlorohydrin rubber (B) Acrylonitrile-butadiene rubber (C) Electronic conductive agent A conductive material in which at least a base elastic layer including at least one conductive elastic layer and a conductive surface layer provided on the outer peripheral surface of the base elastic layer are provided on the outer peripheral surface of the conductive support in this order. A sex roll,
A conductive roll characterized by satisfying the following conditions (4) to (6).
(4) The volume resistance value (Rv2) of the conductive roll in an environment of 22 ° C. and 55% RH is in the range of 10 ⁷ to 10 ⁹ Ω.
(5) The difference of the common logarithm value of the volume resistance value (Rv2) of the said conductive roll in 28 degreeC85% RH and 10 degreeC15% RH is 0.5 or less.
(6) The amount of change in the volume resistance value (Rv2) of the conductive roll by applying a current of 20 μA continuously in an environment of 10 ° C. and 15% RH for 25 hours is 0.5 or less as a common logarithmic value. An image forming apparatus comprising at least one conductive roll and forming an image using toner,
The image forming apparatus, wherein the conductive roll is the conductive roll according to claim 1.

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