JPH05107874A - Semi-conductive roller - Google Patents

Abstract

PURPOSE:To provide the semiconductive roller for an electrophotographic system having excellent toner filming resistance and ozone resistance and a high dielectric breakdown voltage. CONSTITUTION:The resistance layer 12 of the semiconductive roller constituted by forming the resistance layer 12 on a conductive base 11 consists essentially of fluororubber or nitrile hydride rubber. Further, the fluororubber is a vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer and is formed by mixing a solvent-soluble fluororesin into fluorine rubber. Further, the fluororesin is a fluoroolefin-hydroxyl group-contg. vinyl ether copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a fax machine,
The present invention relates to a semiconductive roller for charging, developing and transferring in an electrophotographic system such as a laser beam printer.

[0002]

2. Description of the Related Art In an electrophotographic copying machine, an original image is formed as an electrostatic latent image on the surface of a photoconductor drum such as an organic photoconductor, selenium, CdS, etc., and toner is attached to this to form a toner image. Copying is performed by transferring and fixing this toner image on a transfer paper. In this case, in order to form an electrostatic latent image on the surface of the photoconductor drum, the surface of the photoconductor drum is charged in advance, and the original image is projected onto the charged portion through an optical system so that it is not exposed to light. An electrostatic latent image is formed by erasing the charging of the charged portion.

As a method of charging the surface of the photosensitive drum prior to the formation of the electrostatic latent image, a corona discharge method has been conventionally used. In the corona discharge method, the surface of the photoconductor drum is subjected to a corona discharge from a corona discharger and subjected to a charging process to impart photosensitivity. In this method, a high voltage of 5 to 8 KV is generally applied to the metal wire, and therefore it is said that the photoreceptor and other parts are deteriorated by active molecules such as ozone due to discharge, or harmful to the human body. In terms of electric power, the current flowing to the photoconductor is only 5 to 30% of the current, and most of the current flows through the shield plate, which causes a problem that the charging means is inefficient.

In order to solve such a problem, recently, a contact charging system in which a semiconductive roller is brought into contact with a surface of a photosensitive drum to rotate so as to charge the surface of the photosensitive drum has attracted attention. Semi-conductive rollers are used in electrophotographic copying machines, etc.
It is used as a developing roller, a transfer roller, etc. in addition to the charging roller. The semi-conductive roller has a conductive elastic layer on the outer periphery of the shaft core, if necessary, and a resistance layer is formed on the outer periphery thereof.

The volume resistance of the resistance layer material is from 10 ⁵ to
Those having a resistivity of 10 ¹³ Ω · cm, preferably 10 ⁶ to 10 ¹² Ω · cm can be used. Generally, it is a polar rubber such as epichlorohydrin rubber, nitrile rubber, acrylic rubber, urethane rubber, chloroprene rubber, or even high resistance synthetic rubber such as silicone rubber, ethylene propylene rubber, styrene-butadiene rubber. It is formed of a composition in which a low resistance substance such as conductive powder (carbon black, metal powder, etc.) is mixed.

However, in the semiconductive roller having the resistance layer as described above, the resistance layer is made of epichlorohydrin rubber,
When it is made of polar rubber such as nitrile rubber or acrylic rubber, or fluororubber, its non-adhesiveness to toner is generally insufficient. Remaining toner particles and paper powder adhere to or adhere to the roller surface, which causes a problem. For example, when toner particles or paper powder adheres and adheres to the surface of the charging roller, the function of the roller charger is lost, and the adhered portion cannot normally charge the photoconductor. Further, when it is used as a developing roller, toner sticking to the surface of the roller more remarkably occurs, which causes an abnormal image such as image unevenness, which is not preferable.

As a drawback in the case where the resistance layer material is a system in which low resistance particles such as carbon black are dispersed in synthetic rubber, dielectric breakdown is likely to occur when a high voltage is applied to the shaft core for use. For example, in the case of a charging roller, if there are pinholes on the surface of the photoconductor, a conductive path leading to the back electrode of the photoconductor will be formed, and an excessive current will flow from the charging roller, lowering the voltage applied to the charging roller. Will end up.
In terms of an image, the negative-positive development has a problem that it appears as black streaks in the longitudinal direction of the contact portion between the surface of the photoconductor and the charging roller.

A semiconductive roller used in an electrophotographic copying machine or the like, particularly as a conventional example used as a charging roller, includes (1) JP-A-50-843 (Canon) a roller made of a semiconductive material. (Ceramics of 10 ⁸ to 10 ¹¹ Ω · cm were used), which was first filed as a technology for a medium resistance layer. (2) Jitsukai Sho 58-88645 (Toshiba) Low resistance of metal oxide to elastic resistor Resistant containing a substance of 10 ⁶ to 10 ⁹ Ω · cm (3) JP-A-58-194061 (Toshiba) Non-adhesive coating (silicone resin, fluororesin (polytetrafluoroethylene)) on a conductive elastic body , Polyethylene resin, polypropylene resin, fluorine-containing acrylic resin, polyamide resin ... All have high resistance (10 ¹⁴ -10 ¹⁶ Ω · cm))
Formed (4) Japanese Patent Application Laid-Open No. 1-142569 (Tokai Rubber) A medium resistance roller having a conductive elastic body coated with hydrin rubber is disclosed.

However, a semiconductive roller which is excellent in non-adhesiveness to toner and ozone resistance and has a high dielectric breakdown voltage has not yet been obtained.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a semiconductive roller which is excellent in non-adhesiveness to toner, is less likely to cause toner filming, has a high dielectric breakdown voltage, and is also excellent in ozone resistance. Another object of the present invention is to provide a semi-conductive roller suitable for a charging roller.

[0011]

According to the present invention, there is provided a semi-conductive roller having a resistance layer formed on a conductive support, the resistance layer being mainly composed of a fluorine-based rubber or a hydrogenated nitrile rubber. A semi-conductive roller, especially the resistance layer is a mixture of a fluorine-containing rubber and a solvent-soluble fluorine resin, and the fluorine-containing rubber is vinylidene fluoride-tetrafluoride. An elastomer comprising an ethylene-hexafluoropropylene copolymer, and further, the solvent-soluble fluororesin is a fluoroolefin-hydroxyl group-containing vinyl ether copolymer cross-linked with isocyanate. A conductive roller is provided.

An electrophotographic apparatus using the contact charging system is shown in FIG.
Although the photoconductor 1 is made of an organic photoconductor, it may be made of selenium, CdS, amorphous silicon or the like. The photoconductor 1 is provided with a charging roller 2 in contact therewith, and a developing device 3 and a transfer paper 4 are arranged in a clockwise direction with the charging roller 2 as a center. A fixing device 6 for fixing the transfer paper 4 discharged from the transfer roller 5 is provided between the transfer roller 5 and the toner cleaner 7 in the vicinity of the photoconductor 1.

The copying is carried out as follows.
Photoreceptor drum 1 rotating in the direction of the arrow (linear velocity: 60 mm /
The charging roller 2 made of a semi-conductive roller having elasticity on the outer peripheral surface of (sec) is rotated while being partially elastically deformed by the photosensitive drum. The contact of the charging roller 2 charges the outer surface of the photosensitive drum. On the surface of the photoconductor thus charged, an electrostatic latent image corresponding to the original is formed on the surface of the photoconductor drum by the exposure mechanism section 8, and the latent image is visualized and transferred to the transfer paper by the transfer roller 5. And is fixed by the fixing device 6. In this way, a copy is obtained. In this case, 85 to 85 of the toner adhered by the transfer roller 5 on the surface of the photoreceptor 1.
Although 95% of the toner is transferred, the remaining toner after the transfer is almost completely removed by the toner cleaner 7, and is further irradiated with the entire surface by the eraser lamp 9 to be initialized for the next charging.

Many semi-conductive rollers such as a charging roller, a developing roller and a transfer roller are used in an electrophotographic copying machine or the like. Such a semiconductive roller has a resistance of 10 ⁶ to 10 ¹² Ω.
-It is desirable that the conductive material has a conductivity of about cm.
A semi-conductive roller having a metallic shaft core 10 as shown in the figure and a conductive elastic layer 11 formed on the outer periphery thereof, and a resistance layer 12 formed along the outer periphery of the conductive elastic layer is used. Has been.

The conductive elastic layer material has a volume resistance of 10 ⁵ Ω · cm or less, preferably 10 ³ Ω · cm or less, and a rubber hardness (JIS A) of 20 to 50 degrees, preferably 25 to 40 degrees. You can use the one of the degree. Generally, it is formed of a composition in which conductive powder (carbon black, metal powder, etc.) is mixed in synthetic rubber such as silicone rubber, ethylene propylene rubber, nitrile rubber, urethane rubber.

Further, since the photosensitive drum 1 shown in FIG. 1 is a so-called hard roller, it is preferable that the charging roller is elastically deformed in order to improve the contact property with the charging roller, but the photosensitive member has a belt shape. In this case, the charging roller does not necessarily need to be elastically deformed. Therefore, when the conductive elastic body layer 11 is not necessary, the resistance layer can be formed directly on the cylindrical surface of the metal having the shaft core.

In the present invention, the resistance layer formed on the conductive elastic body layer is mainly composed of fluorine rubber or hydrogenated nitrile rubber. For example, a mixed system of fluorine rubber and solvent-soluble fluorine resin is used. A semiconductive material containing no conductive particles is preferable. This fluororubber is an elastomer of vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer and has a molecular structure and characteristics different from those of conventional fluororubbers. This polymer has a high fluorine content of 67 wt%, and is relatively non-adhesive to toner and the like. The electric resistance value has a medium resistance region, the temperature-humidity dependence of this electric characteristic is extremely small, the voltage causing dielectric breakdown is sufficiently high, and the mechanical strength is sufficiently high to withstand actual use. When the resistance layer is formed of such a polymer single system mainly composed of fluororubber, toner filming can be prevented and the stable function of the roller can be maintained for a long period of time.

However, by mixing this fluororubber with a solvent-soluble fluororesin, the non-adhesiveness can be further greatly improved without impairing other properties, and adhesion of toner or the like to the roller surface can be prevented. It was found that the function as a roller can be maintained for a long time. The solvent-soluble fluororesin used here is an amorphous polymer obtained by a copolymerization reaction of a fluoroolefin and a hydrocarbon vinyl ether, and the details are described in Kojima, Yamabe, "Organic Synthetic Chemistry" 42 (8). , 841
(1984), Munakata, Miyazaki, Kaya, Takayanagi, "Asahi Glass Research Report" 34 (2), 205-224 (1984), Japanese Examined Patent Publications 63-1962, 63-2304, 63-2992.
Reference can be made to the publication. The resin has a relatively low fluorine content of 25 to 32 wt%, but it is an alternating copolymer having a chain structure in which fluoroolefins and hydrocarbon vinyl ethers are alternately arranged, and chemically stable full olefin moieties are regularly formed. Since they are arranged and the unstable hydrocarbon vinyl ether moiety is protected electronically, they are chemically stable and excellent in durability. Also, this polymer is soluble in organic solvents, so after coating, crosslink the polymer,
Although it is necessary to impart solvent resistance to the coating film, for this purpose, a highly reactive vinyl ether having a hydroxyl group is copolymerized and cross-linked and cured by a polyfunctional isocyanate.

The resistance layer is preferably a semi-conductive material containing hydrogenated nitrile rubber as a main component and containing no conductive particles. Nitrile rubber is a copolymer of butadiene and acrylonitrile represented by the following chemical formula 1.

[Chemical 1] It is useful because the medium resistance region can be easily controlled and the cost is relatively low by changing the nitrile content of the rubber obtained by It is not a reliable semiconductive roller material due to the problem of toner sticking to the roller surface due to lack of property, and also the problem of cracking of the roller surface due to ozone deterioration which is a weak point of nitrile rubber. It was However, the hydrogenated nitrile rubber of the present invention is represented by the following chemical formula 2,

[Chemical 2] By highly hydrogenating the main chain of nitrile rubber, while maintaining the features of nitrile rubber, it is possible to greatly improve the non-adhesiveness to toner and ozone resistance, which are disadvantages.

Next, the production of the semiconductive roller of the present invention will be specifically described. As a material for an electrically conductive support having elasticity, for example, a peroxide compound is added to a rubber compound in which carbon black is dispersed in a heat-vulcanizable silicone rubber, which is sufficiently kneaded using a two-roller, and uniformly mixed. A carbon dispersion rubber compound having a different composition is obtained. Wrap this rubber compound around the outer circumference of the metal shaft,
Inserted in a roller molding die heated to 120 kg
Vulcanization (primary) is performed for 10 minutes by applying a pressure of / cm ² . Next, the pressure of the molding die is released, the roller is taken out, and then vulcanization (secondary) is performed at 200 ° C. for 4 hours. After that, the roller surface is ground to obtain a required outer diameter dimension, and at the same time, the surface roughness is set to 3 to 10 μm (Rz) or less. Then
It is possible to obtain a target semi-conductive roller by preparing a coating liquid composed of the resistance layer material, coating the outer periphery of the conductive elastic roller previously prepared by an air spray method or a dipping method, and then drying.

The present invention will be described in more detail with reference to the following examples. Example 1 As a material for a conductive elastic layer, a mixture having the following composition was kneaded to form a rubber compound having a uniform composition, and then a metal mold (1
After the primary vulcanization at 70 ° C. for 10 minutes and 120 kg / cm ² ), the secondary vulcanization (200 ° C., 4 hours) was performed. Thermal vulcanization type silicone rubber 100 parts by weight (DY32-931U: manufactured by Toray Dow Corning Silicone) Thermal vulcanization type silicone rubber 100 parts by weight (SRX-557: manufactured by Toray Dow Corning Silicone) Vulcanizing agent 2.5-dimethyl -2.5-Di (tert-butylperoxy) hexane 6 parts by weight (RC-4: manufactured by Toray Dow Corning Silicone Co., Ltd.) Next, the surface is polished to have a surface roughness of 4 μm (Rz) and an outer diameter of φ1.
2mm finish, volume resistance 3 × 10 ³ Ω on the conductive shaft
A roller having a conductive elastic layer having a cm and a rubber hardness of 35 degrees (JIS.A) was obtained. The circumference of the obtained conductive elastic roller was coated with a coating solution having the following uniform composition by an air spray method, and then 180
The coating was crosslinked and cured at 30 ° C. for 30 minutes to obtain a coating film having a thickness of 50 μm on the conductive elastic roller. Rubber hardness 35 degrees (JIS.
A semiconductive roller intended in A) was obtained. Vinylidene fluoride-tetrafluoroethylene 100 parts by weight-Propylene hexafluoride copolymer Elastomer (Eight seal F-20UI: Ohira Kasei Co., Ltd.) Polyamine crosslinking agent 4 parts by weight (Eight seal curing agent F-20UI: Odaira Kasei) (Mfd.) 4-methyl-2-pentanone / butyl acetate (1: 1 mixed solvent) 400 parts by weight

Comparative Example 1 The same conductive elastic roller as in Example 1 was used. Then, a coating solution of the following uniform composition was coated on the circumference of the conductive elastic roller by an air spray method, and then crosslinked and cured at 170 ° C. for 30 minutes to give a film thickness of 50 μm and a rubber hardness of 35 degrees (JIS. .A) semiconductive roller was obtained. Epichlorohydrin rubber 100 parts by weight (Epichroma CG: Osaka Soda Co., Ltd.) Lead trioxide 5 parts by weight Nickel dibutyl dithiocarbamate 1 part by weight (Antigen NBC: Sumitomo Chemical Co., Ltd.) 2-mercaptoimidazoline 1.5 parts by weight (Sokushinol 22) : Sumitomo Chemical Co., Ltd.) Toluene 1600 parts by weight

The semi-conductive roller thus obtained is mounted as a charging roller of the electrophotographic copying apparatus shown in FIG. 1 so that the toner filming property with time and the volume resistance of the electrical characteristics are dielectrically broken down. Each voltage was evaluated and measured.
The results are shown in Table 1.

[0024]

[Table 1]

The evaluation method and measurement method were as follows. (1) Toner filming resistance Using the apparatus of FIG. 1, after 50 hours of operation and 100 hours of operation,
The toner adhesion state on the surface of the charging roller after 200 hours, 400 hours and 1000 hours was evaluated according to the following criteria. Rank: Toner on the roller surface can be easily wiped off with a cloth. 〃… Some toner remains after wiping. 〃… Cannot be wiped off completely, leaving a thin layer of toner. 〃… Toner is strongly adhered to the roller surface. (2) Volume resistance A thin aluminum plate (thickness 0.5
mm) with a resistance layer material by dipping to a thickness of 5
Samples coated to 0 μm at 20 ℃, 60%
R. After being left in an H environment for 16 hours, measurement was performed using a resistance measurement cell (16008A manufactured by YHP) and a resistance meter (Electrometer 610C manufactured by Keithley Co.). The roller was measured by measuring the sample at 20 ° C. and 60% R.C. After being left in the environment of H for 16 hours, a 10 mm wide copper foil tape (3M Scotch tape No. 1245) was used as an electrode, the distance between the main electrode and the guard electrode was set to 1 mm, and the resistance meter (made by Keithley Co., Ltd. was used. , Electrometer 610C). (3) Dielectric breakdown voltage The sample roller was set to 20 ° C and 60% R.V. 1 in the environment of H
After standing for 6 hours, a DC voltage was gradually increased and applied between the main electrode having a width of 10 mm and the shaft core, and the minimum voltage at which dielectric breakdown occurred was determined.

From the above results, the roller of Example 1 is comparative example 1
It is found that the toner is superior in toner filming resistance to the roller No. 1 and can be used as a good charging roller.

Examples 2 to 5 The same conductive elastic roller as in Example 1 was used. As the material for the resistance layer, a fluororubber coating liquid (liquid A) and a fluororesin coating liquid (liquid B) having the following uniform composition were prepared. (Liquid A-polymer solid content 4.7% by weight) Vinylidene fluoride-tetrafluoroethylene-hexafluoride 100 parts by weight Propylene copolymer elastomer (Eight seal F-20UI: manufactured by Ohira Kasei Co., Ltd.) Polyamine crosslinking agent 4 parts by weight (Eight seal F-20UI curing agent: manufactured by Odaira Kasei Co., Ltd.) 4-methyl-2-pentanone 433 parts by weight (solution B-polymer solid content 10.8% by weight) Solution-soluble fluororesin 100 parts by weight (Lumiflon LF -601C: Asahi Glass Co., Ltd.) Isocyanate curing agent 10 parts by weight (Coronate HX: Nippon Polyurethane Co., Ltd.) 4-Methyl-2-pentanone 455 parts by weight Fluororubber coating liquid (A liquid) and fluororesin coating liquid (B liquid) A mixed coating solution with a different mixing ratio with is applied to the air spray method on the roller surface having the conductive elastic layer obtained previously. Therefore, after coating, 180 ℃,
After 30 minutes of crosslinking and curing, a coating having a thickness of 30 μm was obtained on the conductive elastic roller.

Example 6 The resistance layer material was coated with the fluororubber coating liquid (liquid A) described in the previous example as a simple substance liquid on the conductive elastic roller by the air spray method, and then 180
Crosslinking and curing were carried out at 30 ° C. for 30 minutes to obtain a 30 μm coating film.
The semiconductive rollers of Examples 2 to 6 thus obtained were mounted as a charging roller of the electrophotographic copying machine shown in FIG. The characteristic volume resistivity and dielectric breakdown voltage were evaluated and measured. The results are shown in Table 2.

[0029]

[Table 2]

The evaluation method and measurement method were as follows. (1) Toner Filming Resistance Using the apparatus shown in FIG. 1, the adhesion state of toner particles on the surface of the charging roller every 500 hours of operation was evaluated in the same manner as in Example 1 (Table 1). (2) Volume resistance A sample obtained by coating the resistance layer coating liquid with an air spray to a thickness of 30 μm was applied at 20 ° C. and 60% R.V.
After standing in the H environment for 16 hours, the measurement was performed in the same manner as in Example 1 (Table 1) except that the resistance measuring cell was used. (3) Dielectric breakdown voltage It was measured in the same manner as in Example 1 (Table 1).

From the above results, the rollers of Examples 2 to 5 are superior in toner adhesion preventing property to the rollers of Example 6 and can be used as good charging rollers.

Examples 7 to 11 The same conductive elastic roller as in Example 1 was used. Next, as a material for the resistance layer, a rubber sheet having a thickness of 2 mm was prepared by a general method of rubber molding under the composition and vulcanization conditions shown in Table 3, and the resistance layer alone was evaluated for its electric resistance and ozone resistance. It was The results are shown in Table 3. A coating solution was prepared by adding 1950 parts by weight of 2-butanone to 117 parts by weight of a rubber compound obtained by sufficiently kneading each of the formulations shown in Table 3. After coating the coating liquid on the outer periphery of the conductive elastic roller prepared above by the air spray method, 180 ° C., 3
Crosslink and harden it in 0 minutes and apply a thickness of 5 on the conductive elastic roller.
A resistance layer coating film having a thickness of 0 μm was formed, and the rubber hardness (JIS.
A) A desired semiconductive roller having a temperature of 35 degrees was obtained.

Comparative Examples 2-3 As the conductive elastic roller, the same one as in Example 1 was used. Next, the resistance layer material has the composition shown in Table 3, and the evaluation of the resistance layer alone and the semiconductive roller was performed in the same manner as in Examples 7 to 11. The semi-conductive roller thus obtained was mounted as a charging roller of the electrophotographic copying machine shown in FIG. 1 to obtain the toner filming property over time, and the volumetric resistance and dielectric breakdown voltage of electrical characteristics, respectively. It was evaluated and measured. The results are shown in Tables 3 and 4.

[0034]

[Table 3]

[0035]

[Table 4]

The evaluation method and measurement method were as follows. (1) Ranking of toner filming resistance The operation shown in FIG.
Example 1 shows the toner adhesion state on the surface of the charging roller after 0 hours.
It evaluated similarly to (Table 1). (2) Rubber hardness The vulcanized rubber physical test method was performed according to JIS K6301. (3) Ozone resistance The vulcanized rubber physical test method was performed with reference to JIS K6301 ozone deterioration test. Next, the test method and evaluation of the deterioration state will be described. (1) Ozone concentration and exposure temperature: 5 ppm, 50 ° C. (2) Exposure time: 3 weeks (3) Evaluation of deterioration state: shown in Table 5.

[Table 5] The deterioration state record is expressed by combining the number of cracks, the size and depth of the cracks. (4) Volume resistance In the resistance measurement of the resistance layer alone, a rubber sample having a thickness of 2 mm was measured at 20 ° C. and 60% R.V. After standing in the H environment for 16 hours, the resistance was measured using a resistance measuring cell (16008A manufactured by YHP) and a resistance meter (electrometer 610C manufactured by Keithle). The roller was measured in the same manner as in Example 1 (Table 1). (5) Dielectric breakdown voltage It was measured in the same manner as in Example 1 (Table 1).

From the above results, the rollers of Examples 7 to 11 are superior to the rollers of Comparative Examples 2 to 3 in toner filming resistance and ozone deterioration resistance, and can be used as good charging rollers. Recognize.

[0038]

The semiconductive roller of the present invention is excellent in non-adhesiveness to the toner, so that toner filming hardly occurs, and the roller surface has a low resistance material such as carbon black. Since it is not a system in which substances are dispersed but a polymer alone has semiconductivity, it has a high dielectric breakdown voltage and good ozone deterioration resistance properties. The characteristics of can be demonstrated.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an electrophotographic copying apparatus using a charging roller of the present invention.

FIG. 2 is a schematic cross-sectional view showing the layer structure of the semiconductive roller of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Charging roller 3 ... Developing device 4 ... Transfer paper 5 ... Transfer roller 6 ... Fixing device 7 ... Toner cleaner 8 ... Exposure mechanism part 9 ... Eraser lamp 10 ... Shaft core 11 ... Conductive elastic layer 12 ... Resistance layer

Claims (4)

[Claims] 1. A semi-conductive roller having a resistance layer formed on a conductive support, wherein the resistance layer is mainly composed of a fluorine-based rubber or a hydrogenated nitrile rubber. Semi-conductive roller. 2. The semiconductive roller according to claim 1, wherein the resistance layer is a mixture of fluorine-based rubber and solvent-soluble fluorine resin. 3. The semiconductive roller according to claim 1, wherein the fluorine-based rubber is mainly composed of an elastomer made of vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer. .. 4. The semiconductive roller according to claim 2, wherein the solvent-soluble fluororesin is a fluoroolefin-hydroxyl group-containing vinyl ether copolymer crosslinked with isocyanate.