JP2001227531A - Conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roller having stable volumetric specific resistance under a wide environmental condition up to high temperature-high humidity from low temperature-low humidity and under high impression voltage. SOLUTION: In this conductive roller 1 for imparting electric charge, a conductive elastic layer 3 is formed on an outer peripheral surface of a conductive shaft body 2, and a resistance adjusting layer 4 is formed on an outer peripheral surface of the conductive elestic layer 3. This resistance adjusting layer 4 is composed of at least two layers including an inner layer 4a composed of a base resin adding no conductive filler and an outer layer 4b by adjusting volumetric specific resistance by adding and dispersing a conductive filler. The inner layer 4a is an independent base resin of, for example, 1014 Ω.cm, and the outer layer 4b is adjusted to 106 to 1012 Ω.cm below the inner layer in volumetric specific resistance by adding and dispersing the conductive filler to a base resin of, for example, 1013 Ω.cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller used in an electrophotographic apparatus, and more particularly to a conductive roller suitably used for a cleaning roller, a charging roller, a transfer roller and the like.

[0002]

2. Description of the Related Art These conductive rollers used in an electrophotographic apparatus have a volume resistivity of 10 ¹⁰ Ω · cm or more depending on a place where the roller is used, and the volume resistivity is increased by an applied voltage. May be required to remain the same. In order to make the surface of the conductive roller have such a high volume resistivity, conventionally, a resin having a high volume resistivity has been used as it is. The resin conducts current by ionic conductivity, which is provided by hydrophilic groups in the resin. Therefore, the volume resistivity of such a resin increases at low temperature and low humidity, and decreases at high temperature and high humidity, resulting in poor environmental stability. Also, when the applied voltage is high, the volume resistivity decreases.
As a result, there is a problem that image quality in electrophotography is affected by environmental conditions and applied voltage.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to at least reduce the volume resistivity of the surface from low-temperature low-humidity to high-temperature high-humidity where an electrophotographic apparatus is used. To provide a conductive roller that is stable under the above environmental conditions and does not significantly change with an applied voltage.

[0004]

According to the present invention, there are provided (a) a good conductive shaft, (b) a conductive elastic layer provided on the outer peripheral surface of the shaft, and (c) a conductive elastic layer provided on the outer peripheral surface of the conductive elastic layer. A resistance adjusting layer provided, comprising a resin to which a conductive filler is not added; an inner layer provided on the conductive elastic layer; and a resin having a volume resistivity adjusted by adding and dispersing a conductive filler, And a resistance adjusting layer comprising at least two layers including an outer layer provided on the inner layer.

According to the present invention, the resistance adjusting layer is composed of at least two layers including an inner layer made of a resin to which a conductive filler is not added and an outer layer made of a resin to which a conductive filler is added. The outer layer is formed by adding and dispersing a conductive filler to a resin having a large volume specific resistance and thus having a small number of hydrophilic groups, so that the volume specific resistance is appropriately adjusted. On the other hand, since the inner layer is formed only of the resin to which the conductive filler is not added, it is possible to prevent the volume specific resistance from being largely changed by the applied voltage.

[0006] By thus forming the resistance adjusting layer into at least a two-layer structure of an inner layer and an outer layer, a conductive roller whose environmental stability is improved and whose resistance does not greatly change by an applied voltage is realized.

Further, the present invention is characterized in that the volume resistivity of the inner layer of the resistance adjusting layer is equal to or greater than the volume resistivity of the conductive elastic layer and the outer layer.

According to the present invention, the environmental stability by the inner layer of the resistance adjusting layer and the reduction of the applied voltage dependency by the outer layer can be effectively achieved, which is preferable. The magnitude relationship between the volume resistivity of the conductive elastic layer and the outer layer is not particularly limited.

The present invention is also characterized in that the inner layer of the resistance adjusting layer is made of a resin having a volume resistivity of 10 ¹³ Ω · cm or more, and the thickness of the inner layer is 20 to 100 μm.

According to the present invention, the volume resistivity of the inner layer is 1
In the case of a resin of 0 ¹³ Ω · cm or more, there are few hydrophilic groups and the temperature is 1
Under a wide range of environmental conditions from low temperature and low humidity of 0 ° C. and a relative temperature of 10% to high temperature and high humidity of a temperature of 35 ° C. and a relative humidity of 85%, the electric resistance of the roller can be stably maintained. The layer thickness is 20 μm
If it is less than 100 μm, there is no point in providing the inner layer. If it exceeds 100 μm, the resistance of the entire resistance adjusting layer increases, which is not preferable.

Further, according to the present invention, the outer layer of the resistance adjusting layer is preferably
A conductive filler is added and dispersed in a resin having a volume resistivity of 10 ¹³ Ω · cm or more, so that the volume resistivity is 10 ⁶ to 10 ¹² Ω · c.
m.

By adopting the configuration of the present invention, a stable volume resistivity can be maintained under the above-mentioned wide environmental conditions, and a large change due to an applied voltage can be effectively prevented. If the volume resistivity is less than 10 ⁶ Ω · cm, for example, it becomes difficult to triboelectrically charge the toner remaining on the photoreceptor, as will be described in the following embodiments. Also,
If this exceeds 10 ¹² Ω · cm, the influence of the voltage applied to the shaft body is unlikely to reach the outer layer.

The conductive filler added to and dispersed in the base resin is not particularly limited, but carbon black (not conductive) used in paints and the like is preferably dispersed in the base resin because it is well dispersed.

Further, the present invention is characterized in that the micro hardness measured on the surface of the resistance adjusting layer is 30 to 50 degrees.

The conductive roller according to the present invention has a micro hardness of 50 degrees or less. Therefore, when the conductive roller comes into contact with a mating member such as a charging roller or a photosensitive member, the conductive roller is deformed accordingly and has a constant nip width. Sufficient charge can be transferred to and from a partner material such as the body. If the micro hardness of the conductive roller exceeds 50 degrees, when the roller comes into contact with the mating material, it is less likely to be deformed, the friction with the mating material increases, and the mating material is further worn or damaged. In addition, the toner adheres to the surface of the roller or the surface of the photoconductor, and an abnormal image is easily generated. Also, when the micro hardness of the roller is 30
If the degree is smaller than the above range, it becomes difficult to secure the shape and the predetermined dimension of the roller, so the above range is set. The micro hardness was measured by fixing a conductive roller and applying a surface hardness meter (MD-1 manufactured by Kobunshi Keiki Co., Ltd.) to the outermost periphery of the roller (the resistance adjusting layer of the present application) from above toward the axis. Hardness.

Further, according to the present invention, the base resin used for the resistance adjusting layer has a tensile stress at 100% elongation of 3.0 to 3.0.
It is characterized by 5.0 MPa.

According to the present invention, the synthetic resin constituting the resistance adjusting layer has a tensile stress (100% modulus) at 100% elongation of 3.0 to 5.0 MPa. As a result, a conductive roller such as a charging roller or a straight cylindrical photosensitive drum that is in contact with a mating material is deformed in accordance with the mating material, and when separated from the mating material, the outer shape is restored to a columnar shape. If the tensile stress at 100% elongation exceeds 5.0 MPa, it becomes difficult to deform according to the mating material when it comes into contact with the mating material, and if it is less than 3.0 MPa, abrasion and layer peeling are likely to occur due to insufficient stress. And cannot be used practically.

[0018]

FIG. 1 is a cross-sectional view of a conductive roller used as a charge applying member according to an embodiment of the present invention, which is perpendicular to the axis of a conductive roller. The conductive roller 1 basically includes a good conductive shaft 2, a conductive elastic layer 3 formed on the outer peripheral surface of the shaft 2, and a resistance adjusting layer 4 formed on the outer peripheral surface of the conductive elastic layer 3. Consists of The shaft body 2 is a slender right circular column shape that is precision-machined for supporting both ends and fitting a drive component.
Metals, for example, iron, aluminum alloy, stainless steel, etc. are preferably used.

The resistance adjusting layer 4 includes an inner layer 4a made of a resin not containing a conductive filler, and an outer layer 4b in which a conductive filler is added and dispersed in a base resin. The volume resistivity of the inner layer 4a is 10 ¹³ Ω · cm or more, and the resin constituting the outer layer 4b has a single volume resistivity of 10 ¹³ Ω · cm or more. The volume resistivity is adjusted to 10 ⁶ to 10 ¹² Ω · cm by addition and dispersion.

FIG. 2 is a sectional view showing a part of a laser printer 5 which is an electrophotographic apparatus provided with the conductive roller 1 shown in FIG. The photoreceptor 6, which is a right cylindrical drum, is uniformly charged to a negative polarity by the charging roller 7, for example, by applying a negative charge to the surface thereof uniformly. As shown by an arrow 8 in FIG.
The charging roller 7 is driven to rotate toward the exposure area 9.
In the exposure region 9, an image is exposed by the laser beam from the exposure unit 11, and the charge in the exposed portion is neutralized to form an electrostatic latent image.

The photosensitive member 6 is further driven to rotate, and a one-component toner 14 is supplied by a developing roller 13 in a developing device 12. The toners 14 are in frictional contact with each other in the developing device 12 by the stirring means 15 or the like, and are frictionally charged to a negative frictionally charged polarity. The developing roller 13 includes-
A potential of 400 V is applied. Therefore, the negative toner 14 is attached from the developing roller 13 to the exposed and neutralized exposed portion of the photoconductor 6 by electrostatic attraction, an electrostatic latent image is visualized, and the toner image 16 is formed. It is formed. The toner image 16 is transferred to a recording paper 18 as a transfer medium by the action of a transfer roller 17 as the photoreceptor 6 rotates.
The toner image 19 is transferred onto the recording paper 18 by electrostatic force. The toner image 19 is fixed on the recording paper 18 by an action such as heating or pressure. The transfer roller 17 is a conductive roller to which a potential of, for example, +1000 V is applied.

The photosensitive member 6 is rigid, and is formed by forming a photosensitive layer on the outer peripheral surface of a drum body made of a metal such as aluminum maintained at a ground potential. The charging roller 7 is formed by forming a conductive elastic layer 24 on the outer peripheral surface of a conductive shaft 23. A power supply 25 is attached to the shaft 23 of the charging roller 7.
As a result, a potential V1 of -1500 V is applied. The charging roller 7 applies a photosensitive layer on the surface of the photoconductor 6 to, for example, −60.
Charge uniformly to 0V. A power source 26 is connected to the shaft 2 of the charging roller 7 to the shaft 2 of the conductive roller 1 for applying electric charges.
Connected between Potential V2 of power supply 26 is, for example, -1000V. In this way, the shaft 2 of the conductive roller 1 for applying the electric charge has V3 (=
V1 + V2 = -2500 V). Thus, the potential V applied to the charging roller 7
1 (= -1500 V) is applied with the same polarity as the normal triboelectric charging polarity during development of the toner 14 in the developing device 12, that is, in this embodiment, a negative potential is applied. The potential V3 (= V1) applied to the conductive roller 1 for applying a charge
+ V2) is the same polarity as the triboelectric charging polarity at the time of development of the toner 14 in the developing device 12, that is, the negative polarity,
The absolute value | V3 | of the potential V3 is a value exceeding the absolute value | V1 | of the potential applied to the charging roller 7.

After the transfer, the residual toner 21 remains and adheres to the surface of the photoreceptor 6. This residual toner 21 is
After the transfer by the transfer roller 17, there is a roller which is charged to a positive polarity which is a polarity opposite to the triboelectric charging polarity at the time of development. The positively charged residual toner 21 moves from the surface of the photoconductor 6 to the surface of the charging roller 7 and contacts the conductive roller 1 from the surface of the charging roller 7 as shown by reference numeral 28.
Rubbed. The residual toners 21 and 28 are charged to a charge polarity at the time of development in the developing device 12, that is, a negative polarity by a function of the conductive roller 1 for imparting charge.
As shown by reference numeral 1, the toner is transferred from the charging roller 7 onto the photoreceptor 6 as shown by reference numeral 32.
At 2, the toner 32 is collected. Therefore, the residual toner 2
By 1, the surface of the photoconductor 6 and the surface of the charging roller 7 are cleaned by a cleanerless method.

Outer layer 4 of conductive roller 1 as charge application
“b” includes a synthetic resin material having a polarity due to normal triboelectric charging of the toner 14 in the developing device 12, for example, a negative polarity in the present embodiment, which has a polarity opposite to the triboelectric sequence. When the material of at least the outer peripheral surface of the toner 14 is a styrene acrylic resin, and the outer layer 4b of the charge applying conductive roller 1 is made of, for example, a polyester polyurethane resin as a base resin, frictional contact between the toner 14 and the conductive roller 1 Accordingly, the outer layer 4b of the conductive roller 1 is charged to a positive polarity, and the toner 28 on the surface of the charging roller 7 is changed to a normal negative polarity in the developing device 12.

As the base resin used for the outer layer 4b from the triboelectric charging order, a polycarbonate polyurethane resin, a polyamide resin, an acrylic resin, a silicone resin, etc. are used in addition to the polyester polyurethane resin. In this way, the outer layer 4b of the conductive roller 1 serving as a charge application is selected to have a polarity opposite to the normal polarity of the toner 14 in the triboelectric charging order, so that the conductive roller 1 is further provided with the normal, for example, negative polarity of the toner 14. By applying the potential V3 having the same polarity, the residual toners 21 and 28 after the transfer can be reliably changed to the normal negative polarity of the toner 14.

The outer layer 4b is made of the above-described volume resistivity of 10 ⁶ to
10 ¹² Ω · cm and below the resistivity of the inner layer, preferably 1
According to the present invention, in order to configure the pressure at 0 ¹⁰ to 10 ¹² Ω · cm,
A conductive filler is added and dispersed in a base resin having a volume resistivity of 10 ¹³ Ω · cm or more. The conductive filler may be carbon particles, such as carbon black, or metal particles, or particles of its oxides, for example, titanium oxide, tin oxide, or zinc oxide particles. Carbon black having poor conductivity is preferably used because it is easily dispersed in a resin.

The inner layer 4a has a volume resistivity of 10 ¹³ Ω · c.
m, for example, a polycarbonate polyurethane resin alone is used in a layer thickness of 20 to 100 μm. Since the conductive filler is not added, even if a high voltage, for example, V3 = 2500 V is applied, the volume resistivity does not largely change, and a constant volume resistivity can be secured as the resistance adjusting layer 4.

FIG. 3 is a simplified sectional view of a laser printer 5 according to another embodiment of the present invention. This embodiment is similar to the above-described embodiment, and corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the charge-applied conductive roller 1 is arranged between the transfer roller 17 and the charging roller 7 so as to contact the surface of the photoconductor 6. The negative potential V3 is applied to the conductive roller 1 as described above. Other configurations are the same as those of the above-described embodiment.

The positive residual toner 21a remaining on the photoreceptor 6 after the transfer is brought into frictional contact with the outer layer 4b of the conductive roller 1, and the potential V3 applied to the conductive roller 1 is reduced. By the action, it is changed to negative polarity. The negative toner 21 b moves on the photoconductor 6, moves on the photoconductor 6 from the charging roller 7, and is collected by the developing roller 13 by the developing device 12. Thus, the cleanerless cleaning process of the photoconductor 6 is performed.

The present invention can be widely practiced in connection with laser printers as well as copiers, facsimile machines and other electrophotographic machines. The conductive roller of the present invention can be used not only to change the charge of the residual toner on the photoconductor 6, but also to change the charge roller 7,
It can be used as the transfer roller 17 and various rollers used in other electrophotographic devices. The photoreceptor 6 may have a belt shape in addition to the drum shape described above.

FIG. 4 is a cross-sectional view for explaining a step of forming the conductive elastic layer 3 of the conductive roller 1. FIG.
FIG. 4 is a cross-sectional view for explaining a step of forming a resistance adjusting layer 4 on the conductive elastic layer 3 of the conductive roller 1. Embodiments will be described below with reference to these drawings.

Example Polyisoprene (manufactured by Idemitsu Kosan Co., Ltd.) 98 as a polyol
%, Carbon black was added and dispersed, and tolylene diisocyanate (T-80 manufactured by Nippon Polyurethane) was mixed as an isocyanate so that the isocyanate index became 1.05, and a catalyst (TOS manufactured by Tosoh Corporation) was added.
YOCAT-NP) was added at 0.2% to obtain a conductive elastic layer stock solution 34 (see FIG. 4).

As shown in FIG. 4A, in a mold 35 in which a straight cylindrical middle mold 37 is assembled into a lower mold 36, the conductive elastic layer stock solution 34 is removed with the upper mold 38 removed. Inject. The inner diameter of the middle mold 37 is ground to about 7 mmφ, and the length is about 200 mm. Next, as shown in FIG.
Is inserted from the upper mold 38 and inserted into the undiluted solution into a recess 39 provided at the center of the lower mold 36. As shown in FIG. 4C, the other end of the shaft body 2 is inserted into the recess 40 provided at the center of the upper mold 38 so that the other end of the shaft body is inserted into the middle mold. Attach to 37. The shaft 2 has an outer diameter of 5 m
steel rod of mφ, length 240mm (Material is free cutting steel SUM23
BD) having a thickness of 6 to 8 μm and electroless nickel plating was used. In the state shown in FIG. 4C, the axis of the shaft body 2 and the axis of the inner peripheral surface of the middle mold 37 coincide with each other.

As shown in FIG. 4C, the lower mold 36 and the middle mold 3
7 and the mold 35 assembled with the upper mold 38 are 150 ± 5.
C. for about 1 hour to crosslink and cure the stock solution 34 in the mold. Thereafter, the mold is removed, and as shown in FIG.
Heat at 12 ° C. for 12 hours for post-crosslinking. Next, the outer peripheral surface was ground to an outer diameter of 7 mmφ with a grinding machine to form a conductive elastic layer 3 having a thickness of 1 mm on the shaft body 2.

On the outer peripheral surface of the conductive elastic layer 3 thus formed, a resistance adjusting layer 4 is formed as shown in FIG. First, as shown in FIG. 5A, polycarbonate-based polyurethane (ME8220L manufactured by Dainichi Seika Kogyo Co., Ltd.)
P) 100 parts by weight of a surface smoothing agent (GS-
30) 0.2 parts were added and mixed, and this was mixed with a 1: 1 dilution solvent 150 of methyl ethyl ketone and dimethylformamide.
To dissolve in the portion to prepare the resistance adjusting inner layer stock solution 42,
The conductive elastic layer 3 is immersed in 1. Thereafter, the conductive elastic layer 3 was pulled up together with the shaft body 2 and dried to form an inner layer 4a having a thickness of about 30 μm on the conductive elastic layer 3 as shown in FIG. Next, as shown in FIG.
Polyester-based polyurethane (ME3 manufactured by Dainichi Seika Kogyo Co., Ltd.)
148 LP), 100 parts by weight, 5.25 parts of carbon black (MA7, manufactured by Mitsubishi Chemical Corporation) and 0.2 parts of a surface smoothing agent (GS-30, manufactured by Toagosei Co., Ltd.) were added and mixed. The conductive elastic layer 3 on which the inner layer 4 a is formed is immersed in the container 43.
Thereafter, the conductive elastic layer 3 is pulled up together with the shaft body 2, as shown in FIG.
As shown in (4), by drying, an outer layer 4b having a thickness of about 30 μm was formed on the inner layer 4a to obtain the conductive roller 1 of the present invention.

The present conductive roller 1 is placed on a metal roll on one side 50.
The resistance value when pressed with a load of 0 g was 10 ⁹ Ω · cm. This value hardly changed even when a voltage of 500 to 2000 V was applied, and the withstand voltage was 2000 V or more. The environmental fluctuation value of the volume resistivity was 10 or less. The environmental fluctuation value refers to the volume specific resistance R1 of the resistance adjusting layer 4 at a low temperature and a low humidity of 15 ° C. and a relative humidity of 10% RH.
The ratio R1 of the volume resistivity R2 of the resistance adjusting layer 4 at high temperature and high humidity at room temperature 35 ° C. and relative humidity 85% RH.
/ R2.

The micro hardness of the conductive roller 1 was 45 degrees, and the micro hardness of the conductive elastic layer 3 before applying the resistance adjusting layer 4 was 35 degrees. The volume resistivity of the polycarbonate polyurethane (ME8220LP) alone (inner layer) at room temperature and normal humidity is 10 ¹² Ω · cm, and the volume resistivity of the polyester polyurethane (ME3148LP) alone at room temperature and normal humidity is 10 ¹³ Ω. Cm, and the volume specific resistance at room temperature and normal humidity of the outer layer in which carbon black (MA7) was added and dispersed was 10 ¹⁰ Ω · cm.

In the laser printer 5 of FIG. 2, at least the outer peripheral surface of the toner 14 is a styrene acrylic resin, and the polyester-based polyurethane of the outer layer 4b has a positive polarity with respect to the toner in the triboelectric sequence. In the embodiment shown in FIG. 2, when 100 copies of an original having a black area of 6% are made by the laser printer 5, the charge-applied conductive roller 1, the charging roller 7, and the transferred image on the photosensitive member 6 No stain due to residual toner was observed.

Comparative Example 1 On the outer peripheral surface of a shaft, a conductive elastic layer was formed on the shaft in the same manner as in the example. Carbon black (MA7) was added to and dispersed in a polyester polyurethane having a volume resistivity of 10 ¹¹ Ω · cm so that the volume resistivity was 10 ¹⁰ Ω · cm, and the same surface smoothing agent and diluent as in the previous example were used. Thus, an undiluted solution for the resistance adjustment layer was obtained. The conductive elastic layer formed on the shaft was repeatedly immersed and dried twice to obtain a 60 μm resistance adjusting layer on the conductive elastic layer. The environmental fluctuation value of the volume resistance value of this conductive roller was about 100. The ratio between the volume resistance when 500 V was applied and the volume resistance when 2000 V was applied was 100 at the same temperature and humidity at a temperature of 23 ° C. and a relative humidity of 53%. This is about twice the conductive roller 1 of the embodiment.

[0040]

According to the first aspect of the present invention, the volume resistivity is adjusted by adding and dispersing a conductive filler to a base resin having a less hydrophilic property in the outer layer which is greatly affected by the environment. This increases the environmental stability of the conductive roller. Also, the inner layer, which is not much affected by the environment,
No conductive filler is added. As a result, the resistance does not change significantly even when a high voltage is applied.

According to the second aspect of the present invention, by limiting the volume resistivity and the layer thickness of the inner layer, a conductive roller having an optimum volume resistivity as the resistance adjusting layer can be realized.

According to the third aspect of the present invention, by limiting the volume resistivity of the outer layer, triboelectric charging of the toner remaining on the photoreceptor is facilitated, and the toner is cleaned and collected in a cleaner-less manner.

According to the fourth and fifth aspects of the present invention, the hardness is low, the conductive roller is easily deformed along a mating material with which the conductive roller is pressed, such as a charging roller or a photosensitive member, and has excellent durability. become.

As described above, since the conductive roller is easily deformed along the mating member, the rotational torque of the mating member does not increase, so that it is possible to eliminate the image trouble caused by the rotation fluctuation of the mating member.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view perpendicular to an axis of a conductive roller 1 according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a part of an electrophotographic apparatus 5 such as a laser printer including the conductive roller 1 shown in FIG.

FIG. 3 is a simplified cross-sectional view of a laser printer 5 according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a step of forming a conductive elastic layer 3 of the conductive roller 1.

FIG. 5 is a cross-sectional view for explaining a step of forming a resistance adjusting layer 4 on the conductive elastic layer 3 of the conductive roller 1.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive roller 2 shaft 3 conductive elastic layer 4 resistance adjusting layer 4 a inner layer 4 b outer layer 5 laser printer 6 photoconductor 7 charging roller 12 developing device 13 developing roller 17 transfer roller 21, 28 residual toner

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H003 BB11 CC05 EE11 2H032 AA05 3J103 AA02 AA15 AA23 AA33 AA51 BA41 BA46 FA02 FA06 FA07 FA12 GA02 GA52 GA64 GA74 HA03 HA04 HA05 HA12 HA15 HA20 HA32 HA41 HA45 HA48 HA52 HA55

Claims (6)

[Claims] 1. A good conductive shaft, (b) a conductive elastic layer provided on the outer peripheral surface of the shaft, and (c) a resistance adjusting layer provided on the outer peripheral surface of the conductive elastic layer. The inner layer provided on the conductive elastic layer, made of a resin to which the conductive filler is not added, and the outer layer provided on the inner layer, made of a resin in which the conductive filler is added and dispersed to adjust the volume resistivity, And a resistance adjusting layer comprising at least two layers. 2. The conductive roller according to claim 1, wherein the volume resistivity of the inner layer of the resistance adjusting layer is equal to or greater than the volume resistivity of the conductive elastic layer and the outer layer. 3. The resistance adjusting layer according to claim 1, wherein the inner layer has a volume resistivity of 10 ¹³ Ω · cm or more, and the inner layer has a thickness of 20 to 100 μm.
Or the conductive roller according to 2. 4. An outer layer of the resistance adjusting layer is adjusted to have a volume resistivity of 10 ⁶ to 10 ¹² Ω · cm by adding and dispersing a conductive filler to a resin having a volume resistivity of 10 ¹³ Ω · cm or more. The conductive roller according to claim 1, wherein: 5. The micro-hardness measured on the surface of the resistance adjusting layer is 30 to 50 degrees.
A conductive roller according to one of the preceding claims. 6. The base resin used for the resistance adjusting layer has a tensile stress at 100% elongation of 3.0 to 5.0 MPa.
The conductive roller according to claim 1, wherein: