JPH037966A - Electrifying member and electrophotographic device using this member - Google Patents

Abstract

PURPOSE:To obtain the electrifying member which is stable in a semiconductor region, is excellent in mass productivity and low in cost and the electrophotographic device for which this member is used by incorporating double oxides consisting of metal oxides in which >=2 kinds of metals coexist into an elastic material. CONSTITUTION:The electrifying member used for the electrophotographic device which can form copies having good image quality even after continuous copying of many sheets is formed by incorporating the double oxides, which are at least one selected from the solid soln. of zinc oxide and aluminum oxide, the solid soln. of tin oxide and antimony oxide, and the solid soln. of indium oxide and tin oxide, into the elastic material. The content of the double oxides in the elastic material is 5 to 40wt.% and more particularly preferable 10 to 30wt.%. Mechanical strength, such as wear resistance, is required for the material itself in the case of using the electrifying member in common use as a material for transporting a transfer material, such as paper, as represented by the roller-shaped electrifying member for transfer. A reinforcing material, such as carbon black, is used in combination in the elastic material in such a case.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charging member, and more particularly to an electrophotographic charging member for transfer, photoreceptor charging, transportation, and paper feeding, and electrophotography using the same. Regarding equipment.

[Prior art]

Problems regarding the electrical resistance of charging members for electrophotography are often raised.

For example, electrophotographic printers such as small laser beam printers that have become widespread in recent years often use an organic photoconductor (hereinafter referred to as OPC) as a photoreceptor and use a reversal development method to develop the exposed area of the image. Often adopted.

In addition, this type of transfer device for printers has the following advantages: it is compact, transfer can be performed with the application of low voltage, there are few corona discharge products such as ozone, and the stability of conveyance of transfer materials such as paper is good. From this point of view, contact roller transfer devices and belt transfer devices are used.

When successfully transferring the toner image on the image carrier onto the transfer material using this type of contact transfer device, if the transfer material has a very high resistance (for example, paper left under low humidity, polyester film, etc.). transperancy paper, etc.),
A strong transfer current is required.

If such a strong transfer electric field is directly applied to the image carrier, an excessive current will flow through the image carrier, damaging the image carrier. This phenomenon becomes particularly noticeable when passing small-sized paper. In order to solve these problems, a semi-conductive region is required as the resistance value of the charging member for transfer.

Similarly, in a contact type charging device for charging a photoconductor, problems when using a conductive charging member for primary charging are that the current value flowing through the photoconductor is large, shortening the life of the photoconductor, and It is known that if the upper pinhole exists, it will cause discharge there and cause image defects.

Therefore, like the charging member for transfer, in order to solve the above problem, 1.
Attempts are being made to solve this problem by setting the electrical resistance of the charging member for subsequent charging to a semi-conductive region and limiting the current flowing into the photoreceptor.

A conventionally known method for obtaining a material with a resistance value in the semiconductive range is to first disperse a conductive filler such as conductive carbon, graphite, or metal powder into an elastic body such as rubber or a resin matrix. There are ways to adjust the resistance, but as is well known, in the semiconducting region, the resistance changes sharply depending on the amount of conductive filler added, so when the conductive filler is mixed, the loss due to scattering of the conductive filler to the outside, the degree of dispersion, etc. A slight difference in the electrical resistance value appears,
Therefore, it lacks reproducibility and poses problems in terms of mass production stability.

In addition, stabilization in the semiconducting resistance range by adding plasticizers, low molecular weight liquid rubbers, and surfactants has been proposed, but when these additives are used, plasticizers, low molecular weight liquid rubbers,
There is a problem in that the surfactant oozes out onto the surface of the charging member and transfers to the photoreceptor placed in contact with the charging member, contaminating the photoreceptor and eventually causing image defects. In addition, the oozing of plasticizers, low molecular weight liquid rubbers, and surfactants onto the surface of the charging member significantly increases stickiness, resulting in adsorption of toner and paper dust, which deteriorates the functionality of the charging member. was there.

Furthermore, there is an example of dispersing a crosslinked silicone rubber pulverized product containing carbon black into silicone rubber as described in JP-A No. 63-156858, but in this case, there are problems such as high manufacturing costs. be.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above points, and an object of the present invention is to provide a charging member that is stable in the semiconducting region, has excellent mass productivity, and is low in cost.

Another object of the present invention is to provide an electrophotographic apparatus that can form copies of good image quality even after continuous copying of a large number of sheets.

[Means for solving problems]

The above object is achieved by the following invention.

That is, the present invention is a charging member characterized by containing a double oxide in an elastic body.

According to the charging member containing a double oxide in the elastic body according to the present invention, it can be manufactured stably and with good reproducibility in the semiconducting region, which was not stable in the past. By adding this additive, it is possible to stably obtain a material with any resistance value in the semiconducting region, and also to impart reinforcing properties and flexibility to the elastic body. When applied to the charging of a photoreceptor, Sufficient nip width can be obtained for
Good charging characteristics can be obtained.

The double oxide used in the present invention is a higher-order compound (a compound formed by bonding between molecules) consisting of two or more types of oxides, and is a metal oxide in which two or more types of metals coexist. . One example of a method for producing a double oxide is to disperse one or more different metal ions in a metal oxide crystal lattice and sinter it in a reducing atmosphere. For example, in the case of a double oxide of zinc oxide and aluminum oxide, it is obtained by treating zinc oxide and aluminum salt in an aqueous ammonium salt solution, dehydrating it, and then calcining it in a hydrogen atmosphere (Japanese Patent Publication No. 62-41
(See Publication No. 171).

Therefore, it is different from a mere metal oxide. Examples of such double oxides include solid solution compounds of zinc oxide (ZnO) and aluminum oxide (AltOa), and tin oxide (S).
Compounds of solid solutions of nO2) and antimony oxide (Ab, 0.'), solid solutions of indium oxide (InzOs) and tin oxide (Sn0.), and compounds of zinc oxide (ZnO) and titanium oxide (Ti, O=) Compounds in solid solution, magnesium oxide (MgO) and aluminum oxide (A j! 20
, ), and solid solution compounds of iron oxide (FeO) and titanium oxide (TiO=).

The characteristics of these double oxides are that the atomic radii of each metal are close, they form a substitutional solid solution, and the valence numbers of each metal are different, so they cannot be obtained with each metal oxide alone. It is possible to obtain conductivity.

The specific resistance value of these double oxides is 101Ω・cm ~ 103
Ω・cm, which is higher than conductive carbon black, reinforcing carbon black, ruthenium oxide (101Ω・cm to 10′Ω・cm), and zinc oxide, aluminum oxide, antimony oxide, and ruthenium oxide. Indium, triiron tetroxide, tin oxide, etc. (104Ω
・cm or more) lower.

That is, the double oxide of the present invention has a resistance of 101 Ω·cm to 10'
When a filler of Ω·Cm is used, stable semiconductivity can be obtained with an amount added that does not cause problems in physical properties, and excellent reproducibility and mass production stability are achieved.

On the other hand, with conventional fillers that are dispersed in a dispersion medium such as a polymer, when the resistivity is less than 101Ω・cm, the resistance value changes rapidly depending on the amount of filler added, as mentioned earlier. Because it is equivalent, it lacks reproducibility and mass production stability.

On the other hand, if it is higher than 10'Ω·cm, a considerably large amount is required to exhibit semiconductivity, making dispersion processing difficult. Even if it were possible to disperse it, the physical properties would be significantly inferior and would not be of practical use. In addition, the hardness is considerably high, causing problems such as insufficient and stable pressure contact with the photoreceptor and the like.

Moreover, among the above-mentioned double oxides, especially Z n O-A l 2
o3 is excellent. The reason for this is that the specific resistance of this filler is 102Ω・cm to 103Ω・cm, which is the most ideal resistance value for resistance stability in the semiconducting region, and that it is suitable for polymeric dispersion media such as resins and rubbers. On the other hand, it is easy to disperse, has excellent processability, and is inexpensive.
Aj! For example, an appropriate resistance value can be achieved depending on the doping amount of (Af2O8).

The content of double oxide in the elastic body is 5 wt% to 40 wt%,
In particular, 10 wt% to 30 wt% is preferable.

Furthermore, when the charging member for transfer is also used to convey a transfer material such as paper, as typified by a roller-shaped charging member for transfer, the material itself is required to have mechanical strength such as wear resistance.

In this case, it is preferable to use a reinforcing agent in addition to the double oxide.

As the reinforcing agent, reinforcing carbon such as carbon black, silica, etc. can be used as appropriate. As a result of our study on the case of using carbon black, we found that the specific resistance is 10°Ω・cm or more, and the amount added is 0.1w.
It has been found that in the range of t% to 20wt%, preferably 1wt% to 15wt%, excellent reinforcing properties and stable resistance can be obtained. In other words, if the specific resistance is less than 106 Ω・cm, the conductive ability is large (even a small amount of addition tends to cause potential unevenness. Also, if the amount of addition exceeds 20 wt%, carbon The degree of dependence on black increases, and the addition of double oxide tends to become meaningless.

Examples of reinforcing carbon include those used for general industrial purposes, such as ISAF (Intermediate
5upper Abrasion Furnace), S
AF (Super Ab-ration Fu)
rnace), HAF (High Ablation Furnace Black), FEF (Fast Extrusio
nFurnace), SRF (Semi
-Reinforcing Furnace), F
T (Fine Thermal), EPC (Easy)
Pro-cessing Channel I
) MPC (Medium Process)
ing Channel).

Further, in the charging member for roller shape transfer and the charging member for roller shape primary charging, by maintaining a sufficient pressure contact area with the photoreceptor, good and uniform charging characteristics and transfer characteristics can be obtained. Therefore, particularly low hardness is required for the above-mentioned uses.

At this time, process oil such as insulating oil is preferably added, but as a result of examining various insulating oils, we found that the specific resistance of the oil is 10 Ω・cm or more, and the amount added is 5.
wt% to 20wt%, preferably 8wt% to 16wt%
It has low hardness, excellent reinforcing properties, and stable resistance value. When oil with a specific resistance of less than 10 Ωcm is used, when it transfers onto the photoconductor, the potential on the photoconductor shifts only at the oil transfer location, which may cause image defects or tend to cause toner to aggregate on the photoconductor. become.

Furthermore, if the amount added exceeds 20 wt%, oozing onto the surface of the charging member becomes noticeable, contaminating the photoreceptor, and the adhesion of toner, paper powder, etc. to the surface of the charging member becomes significant, and the function as a charging member is impaired. Problems with deterioration are likely to occur.

Examples of such insulating oil include paraffin oil and mineral oil.

Examples of the elastic body in the present invention include EPDM (ethylene-propylene-diene-A-polymer), polybutadiene, natural rubber, polyisoprene, 5BR (styrene-butadiene rubber), CR (chloroprene rubber), N
Rubbers such as tolyl butadiene rubber (BR), silicone rubber, urethane rubber, and ebichlorohydrin rubber, and RB (
butadiene resin), polystyrene type such as 5BS (styrene-butadiene-styrene elastomer), polyolefin type, polyester type, polyurethane type, thermoplastic elastomer such as PvC, polyurethane, polystyrene,
PE (polyethylene), PP (polypropylene), Pv
Polymer materials such as C (polyvinyl chloride), acrylic resin, styrene-vinyl acetate copolymer, butadiene-acrylontrile copolymer, etc. can be used. Further, the elastic body can be used as a foam or as a solid rubber.

Furthermore, if necessary, calcium carbonate, various clays,
Talc etc. or blends thereof,
Fillers such as silica-based fillers such as hydrous silicic acid, anhydrous silicic acid, and their respective salts may be added.

In addition, when using a foaming agent, examples of the foaming agent include A, D,
C, A, (azodicarponamide) system, D, P, T, (di-nitrosopentamethylenetetramine) system, 0. B,S
, H, (4,4'-oxybis-benzenesulfonyl hydrazide) system, T, S, H, (P-toluenesulfonyl hydrazide) system, A, 1. B, N, (azobisisobutyronitrile) series, etc. can be used, especially A, D, C, A, series, 0. Blends of B, S, and H systems yield dense foams with tight vulcanization (high crosslinking density).

In the case of polymers where the strength and flexibility of the material can be changed by adjusting the polymer structure of the polymer itself, as seen in certain polymers such as urethane rubber and silicone rubber, only the addition of a double oxide is sufficient. It is possible to achieve the hardness and strength required for practical use without necessarily adding reinforcing fillers such as carbon black or softeners.

In addition, the specific resistance of the powder in the present invention is the applied load of 100
It was measured in Kg/ci at 25° C. and 60RH% using a general powder resistance measurement method.

The shape of the charging member of the present invention may be a roller, a blade, etc. (it can be selected depending on the specifications of the electrophotographic apparatus).

FIG. 1 shows the basic configuration of a roller-shaped charging member 1, in which an elastic body 3 containing a double oxide is formed on a cylindrical conductive substrate 2.

Further, when the charging member is in the shape of a blade, an elastic body containing a double oxide may be formed on a plate-shaped conductive substrate.

As the conductive substrate, metals such as iron, copper, stainless steel, metal alloys, conductive resins, etc. can be used.

For example, when charging a photoreceptor using the charging member of the present invention, by applying a voltage from the outside to the conductive base of the charging member, the photoreceptor placed in contact with the charging member is charged. Can be charged.

Charging is carried out by bringing a charging member into contact with the surface of the photoreceptor, but the surface of the photoreceptor is charged by the charging member to which a voltage is applied in the slight gap between the photoreceptor and the charging member, that is, the photoreceptor. This is because discharge occurs through a thin wedge-shaped space outside the contact area between the body and the charging member. The purpose of bringing the charging member into contact with the photoreceptor is to create such a small gap. That is, the above-mentioned minute gap is maintained by the contact of the charging member with the photoreceptor.

The charging member of the present invention can be used not only for transfer, primary charging, and neutralization, but also for transporting paper feed rollers and the like. Friction between the transport roller and the transfer material causes the roller contact area of the transfer material to become electrically charged, causing uneven charging on the transfer material itself, resulting in uneven images.This material was developed as a means to solve this problem. shall be applied.

As a photoconductor to which the charging member of the present invention can be used, oPC (
Organic photoconductor) Photoreceptor, A-8i.

Various photoreceptors such as Se and ZnO can be used. In particular, by using the charging member of the present invention in an OPC photoreceptor that is susceptible to deterioration in terms of mechanical strength and chemical stability, its characteristics can be significantly exhibited.

Electrophotographic devices that can use the charging member of the present invention include:
Copy machine, laser beam printer, LED printer,
Another example is an electrophotographic application device such as an electrophotographic engraving system.

FIG. 2 is a schematic diagram of an electrophotographic apparatus to which the charging member according to the present invention is applied as a charging member for transfer.

In this electrophotographic apparatus, a photoreceptor 4 sensitized to near infrared light is used as a photoreceptor, and after being uniformly charged with negative polarity by a charging roller 5, the photoreceptor is modulated by an image signal and then raster-scanned by a laser beam. The light 6 lowers the potential of the image area to form an electrostatic latent image, which is visualized by the negative polarity toner in the developing device 7. Thereafter, the toner image T on the photoreceptor 4 is transferred onto the transfer material P by the charging member 1 for roller shape transfer to which a positive voltage is applied. Furthermore, the transfer material P onto which the toner image T has been transferred is then conveyed to a fixing device (not shown), where the toner image T is permanently fixed. Transfer residual toner on the photoreceptor 4 is cleaned by a cleaner 8,
Repeat the same process again.

An electrophotographic apparatus is constructed by combining a plurality of components such as the above-mentioned photoreceptor, developing means, and cleaner into an apparatus unit, and this unit is configured to be detachable from the apparatus main body. Also good. For example, photoreceptor 4
The cleaner 8 and cleaner 8 may be integrated into one device unit, and configured to be detachable using a guide means such as a rail of the device body. At this time, the above-mentioned device unit may include a charging means and/or a developing means.

In addition, when using an electrophotographic device as a copying machine or printer, optical image exposure involves
Alternatively, the original is read and converted into a signal, and this signal is used to scan a laser beam, drive a light emitting diode array, or drive a liquid crystal shutter array.

Furthermore, when used as a facsimile printer, the optical image exposure is exposure for printing received data. FIG. 3 is a block diagram showing an example of this case.

The controller 11 controls the image reading section 10 and the printer 19. The entire controller 11 is controlled by a CPU 17. The read data from the image reading section is transmitted to the partner station through the transmitting circuit 13. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. Predetermined image data is stored in the image memory.

A printer controller 18 controls a printer 19. 14 is a telephone.

After the image received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, the CPU 17 decodes the image information and sequentially stores it in the image memory 16. Ru. and at least 1
When the image of the page is stored in the memory 16, the image of the page is recorded. The CPU 17 reads one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. When the printer controller 18 receives one page of image information from the CPU 17, it controls the printer 19 to record the image information of that page.

Note that the CPU 17 receives the next page while the printer 19 is recording. As described above, images are received and recorded.

Example I EPDM (EPT4045 Mitsui Petrochemical) 100 parts by weight (hereinafter referred to as parts) as a dispersion polymer, 10 parts of Zinc White No. 1, 2 parts of stearic acid, 2 parts of Accelerator M (Tsukusela M Ohmukai Shinko Chemical) , 1 part of accelerator BZ (Tsukusera BZ Ouchi Shinko Kagaku), 2 parts of sulfur, 5 parts of foaming agent (Celmic C Sankyo Kasei), 5 parts of foaming aid (Celton NP Sankyo Kasei),
Furthermore, the reinforcing agent, insulating oil, and others are mixed according to the respective compositions shown in Table 1, and the mixture is uniformly dispersed and kneaded using two rolls.The rubber is then wrapped around a primer-applied iron core and placed in a mold. Insert, 40°C1100K gf/
preformed at Crd and steam vulcanized (160
C. for 30 minutes) and then polished to produce roller-shaped charging members A to E. This dimension is core metal diameter 6mm.

Outer diameter 16mm, core length 250mm, rubber length 230m
It was m. For resistance measurement, a total of IKg was loaded onto the AA plate at 500 g on both ends, and the resistance between the core metal and the AA plate was measured (23° C., 50 RH).

The values in Table 1 are in parts by weight. Figure 4 shows the relationship between the resistance value of each charging member thus obtained and the number of parts added of each filler (relative to 100 parts by weight of rubber).

As is clear from FIG. 4, by adding Zn0-Ajl'203 double oxide in a predetermined semiconducting region, the resistance fluctuation can be stabilized with little change in the amount of addition.

Furthermore, by changing the ratio of reinforcing carbon and insulating oil, a stable resistance value can be set arbitrarily.

In addition, when conducting a resistance value reproducibility test for each formulation, it was found that in the case of conductive carbon (Ketchen Black EC), 12
In the case of phr addition, a variation of 3 orders of magnitude (5 x 10" Ω to 5 (measured value xi, 125
It was found that the variation was within the measurement error range (~measured value x 0.875). Furthermore, with respect to the charging member E, even if the amount of Fe50< added is varied within the -radial range, the desired semiconducting region cannot be achieved.

Example 2 100 copies of EPDM (EPT4045 Mitsui Ishiura Chemical),
10 parts of zinc white No. 1, 2 parts of stearic acid, ZnO-A
120 m 100 parts, Accelerator M (Tsukusera M Omukai Shinko Kagaku) 2 parts, Accelerator BZ (Tsukusera BZ Ouchi Shinko Kagaku) 1 part, sulfur 2 parts, foaming agent (Celmic C Sanki Kasei) 5 parts, foaming A roller-shaped charging member 1 was produced by the same manufacturing method as described above using a blending composition of 5 parts of an auxiliary agent (Selton NP Sankyo Kasei), 45 parts of HAF carbon as a reinforcing agent, and 60 parts of paraffin oil as an insulating oil.

Further, a roller-shaped charging member 2 was prepared with the same composition as the charging member 1 except that 50 parts of HAF carbon and 65 parts of paraffin oil were used.

Also, 45 parts of HAF carbon and 5 parts of paraffin oil.
A roller-shaped charging member 3 was prepared with the same composition as the charging member 1 except that the amount was 5 parts.

Also, Zn0-Aj! 20.150 parts, silicone rubber (
KE 520 Shin-Etsu Chemical) 100 parts, silicone crosslinking agent (C
8 (manufactured by Shin-Etsu Chemical Co., Ltd.) and 5 parts of ArBNl, primary vulcanization (250°C Cl2O) and further secondary vulcanization (200'C, 4 hours) were performed to form a roller-shaped charging member 4.
was created.

Further, a roller-shaped charging member 5 was produced in the same manner as the roller-shaped charging member 3 except that 70 parts of r nx 03 ”s n'o2 was used.

Also, 20 parts of HAF carbon and 7 parts of paraffin oil.
A roller-shaped charging member 6 was prepared in the same manner as charging member A except that 0 parts of Ketchen Black EC and 20 parts of Ketchen Black EC were used.

Further, a roller-shaped charging member 7 was produced in the same manner as the roller-shaped charging member E except that 100 parts of Fe30a was used.

Table 2 shows the hardness and electrical resistance values of the roller-shaped charging members 1 to 7 thus produced.

Further, the roller-shaped charging members 1 to 7 are connected to an electrophotographic apparatus (
The electrophotographic device was installed as a charging member for transfer in a laser beam printer (laser beam printer), and image output was evaluated using the electrophotographic apparatus shown in FIG.

This device uses an OPC drum with a diameter of 40 mm, and the dark area potential (Vo) is -000 V and the light area potential (VL) is -100 V.
(2), and reversal development was performed using an insulating magnetic toner with a negative component. Copy paper with a basis weight of 64 glrd was used as the transfer material. Further, the paper feeding speed was 40 mm/sec.

The configuration of the OPC drum is as follows.

An aluminum cylinder measuring 40φ×260 mm and having a wall thickness of 0.5 mm was prepared as a base.

Copolymerized nylon (product name: CM8000. Manufactured by Toshi ■) 4
Type 8 nylon (trade name Niratsukamite 50)
03, manufactured by Dainippon Ink ■) and 50 parts of methanol, n
- It was dissolved in 50 parts of butanol and dip coated onto the above substrate to form a 0.6 μm thick polyamide undercoat layer.

Next, 10 parts of a disazo pigment having the following structural formula and 10 parts of polyvinyl butyral (Eslec BM2, manufactured by Block Chemical Co., Ltd.) and 120 parts of cyclohexanone were dispersed in a sand mill for 10 hours. 30 parts of methyl ethyl ketone was added to the dispersion and coated on the undercoat layer to form a charge generation layer with a thickness of 0.15 μm.

Prepare 10 parts of polycarbonate Z resin (manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a weight average molecular weight of 120,000, and add 80 parts of monochlorobenzene together with 10 parts of a hydrazone compound having the following structural formula.
It was dissolved in parts.

This was coated on the above charge generation layer to form a charge transport layer with a thickness of 18 μm to prepare an OPC drum.

The charging roller 5 had a conductive rubber layer on a core metal, and was a roller made of 106Ω conductive urethane rubber. Here, the resistance represents the resistance from the core metal to the roller surface per 1 crrf of the roller surface. The charging roller 5 applies a predetermined pressure (
For example, the photoreceptor is kept in a pressed state with a linear pressure of 0.01 to 0.2 kg/cm), and the photoreceptor is uniformly charged by applying a predetermined voltage. In this embodiment, a charging roller is shown as the charging means, but other conventionally employed corona chargers may be used.

Example 3 100 parts by weight of CR rubber (WM-1 Showa Neorene@) (
(hereinafter simply parts) MgO (Kiyowa Mag 150) 4 parts Ketchen Black EC 9 parts C1rco Light, R, P, 0 30 parts (Nippon Sun Oil) Neofactis-N (Tenma Sub Kako) 20 parts Paraffin wax (Mobil Oil) 2 parts CML #21 (
Ohmi Chemical) 2nd part ZnO No. 1
5 parts Accelerator 22S (Kawaguchi Chemical Industry)
1.6 parts Accelerator BUR 2 parts Cellmic 0 8 parts Selton NP (Sanki Kasei) A mixture of 4 parts or more, uniformly dispersed and kneaded using two rolls, and then mixed into an iron core metal coated with brimer. Wrap rubber around it, put it in a mold, preform at 40℃, 100Kg f/c tri, and steam vulcanize it (150℃, 30 minutes)
A base elastic layer was prepared by vulcanizing the material and then polishing it. The dimensions at this time are core diameter 6 mm, outer diameter 11
The length of the metal core was 250 mm, and the length of the rubber was 240 mm.

Next, EPDM rubber (EPT4045 Mitsui Petrochemical) 10
0 parts, zinc white No. 1 10 parts, stearic acid 2 parts, accelerator M
2 parts, 21 parts of accelerator B, 2 parts of sulfur, 60 parts of paraffin oil, 45 parts of HAF carbon, ZnO-Alx O-
It was mixed with a composition of 100 parts, uniformly dispersed and kneaded using two rolls, and then processed into the above-mentioned CR using a crosshead extruder.
A sponge roller was coated and preformed, this was again vulcanized by steam vulcanization at 160° C. for 30 minutes, and then polished to produce a roller-shaped charging member. The completed roller-shaped charging member had an outer diameter of 12 mm and a rubber length of 230 mm. The roller resistance at this time is
The method shown in the figure, i.e., a width of 10 mm on the charging roller base layer 20
It was measured by winding aluminum foil 21 of mm in diameter, applying DC IKV between the core metal and the aluminum foil from the power source 22, measuring the current, and measuring the resistance value between the core metal and the aluminum foil.
It was 7 Ω·cm (25° C., 60% RH).

This roller was used as the charging roller 5 in FIG. 2, and the roller No. 1 of Example 2 was used as the transfer roller, and the voltage was applied to the charging roller 5 at an AC frequency of 150 Hz.
Image quality was evaluated in the same manner as in Example 2 except that the AC peak-to-peak voltage was 2 KV and the DC voltage was 700 V. Even after 100,000 copies, the same high image quality as the initial image quality was obtained.

In addition, a pinhole with a diameter of about 0.5 mm was made on the OPC drum photoreceptor, and the temperature was 15°C, 10%RH, 125°C, 60%RH.
, 32.5°C, 185% RH, and in the same environment.As a result, the surface layer of the charging roller and the underlying elastic layer did not suffer from current damage in all three environments, and the charging roller was sufficiently A high charging potential was obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view (left figure) and parallel cross-sectional view (right figure) in the axial direction of the charging member of the present invention, and FIG. 2 is a schematic cross-sectional view of the electrophotographic apparatus used in this example. Figure 3 is a block diagram of a facsimile machine using the electrophotographic device according to the present invention as a printer, Figure 4 is a graph showing the relationship between the amount of additive added and the resistance of the charging member, and Figure 5 is the resistance of the roll-shaped charging member. It is an explanatory diagram of measurement. 1...Charging member 2...Conductive base 3...Elastic body

Claims (1)

[Scope of Claims] (1) A charging member characterized by containing a double oxide in an elastic body. (2) The charging member according to claim 1, wherein the double oxide is at least one selected from a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of indium oxide and tin oxide. . (3) The charging member according to claim 1, wherein the content of the double oxide in the elastic body is 5 to 40 wt%. (4) Claim 1 containing a reinforcing agent in the elastic body
Charging member described in section. (5) The charging member according to claim 4, wherein the reinforcing agent is carbon black. (6) The charging member according to claim 1, wherein the elastic body contains insulating oil. (7) Multiple oxide in elastic body, 0.1wt% to 20wt%
Claim 1, characterized in that it contains carbon black and 5wt% to 20wt% of insulating oil.
Charging member described in section. (8) The charging member according to claim 7, wherein the double oxide is a solid solution of zinc oxide and aluminum oxide. (9) An electrophotographic apparatus comprising an electrophotographic photoreceptor and a charging member containing a double oxide in an elastic body that is in contact with the surface of the electrophotographic photoreceptor. (10) An electrophotographic apparatus according to claim 9, wherein the charging member is disposed at a position where the toner image formed on the surface of the electrophotographic photoreceptor is transferred to a transfer material. (11) An electrophotographic apparatus according to claim 9, wherein the charging member is disposed at a position to uniformly charge the electrophotographic photoreceptor. (12) The electrophotography according to claim 9, wherein the double oxide is at least one selected from a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of indium oxide and tin oxide. Device. (13) Multiple oxide in elastic body, 0.1 wt% to 20 wt%
13. The electrophotographic apparatus of claim 12, comprising 5% to 20% carbon black and 5% to 20% insulating oil. (14) The electrophotographic apparatus according to claim 13, wherein the double oxide is a solid solution of zinc oxide and aluminum oxide. (15) An electrophotographic apparatus having an electrophotographic photoreceptor and a charging member containing a double oxide in an elastic body, which is in contact with the surface of the electrophotographic photoreceptor, and a receiving means for receiving image information from a remote terminal. A facsimile machine comprising: (16) The facsimile according to claim 15, wherein the double oxide is at least one selected from a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of indium oxide and tin oxide.