JP2633054B2 - Charging member and electrophotographic apparatus using the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member, and more particularly, to an electrophotographic charging member for transfer, charging of a photoreceptor or conveyance and paper feeding, and an electrophotography using the same. Related to the device.

(Prior art)

Problems relating to the electrical resistance of an electrophotographic charging member are often raised.

Taking an example of an electrophotographic printer such as a small laser beam printer that has become widespread in recent years, in many cases, a reversal developing method in which an organic photoconductor (hereinafter referred to as OPC) is used as a photoconductor and an image exposure unit is developed. Often employed.

In addition, as this type of transfer device for a printer, the size of the device can be reduced, transfer can be performed by applying a low voltage, there are few corona discharge products such as ozone, and the transfer stability of a transfer material such as paper is good. Use a contact roller transfer device or a belt transfer device.

When a toner image of an image carrier is satisfactorily transferred onto a transfer material in a contact-type transfer device of this type, when the transfer material has a very high resistance (for example, paper or polyester film left under humid conditions). (Transparency paper, etc.), and a strong transfer current is required.

When such a strong transfer electric field is directly applied to the image carrier, an excessive current flows through the image carrier, and damages the image carrier. This phenomenon becomes remarkable especially when small-sized paper is passed. To solve these problems, a semiconductive region is required as a resistance value of the transfer charging member.

Similarly, in a contact-type charging device for charging a photoreceptor, a problem when a conductive primary charging member is used is as follows.
It is known that the current value flowing through the photoconductor is large, the life of the photoconductor is shortened, and if there is a pinhole on the photoconductor, a discharge is caused there to cause an image defect. Therefore, in order to solve the above problem similarly to the charging member for transfer, the electric resistance of the charging member for primary charging is set to a semiconductive region,
An attempt is made to solve the problem by limiting the current flowing into the photoconductor.

As a method of obtaining a material having a resistance value of a semiconductive region, a conventionally known method is to first disperse a conductive filler such as conductive carbon, graphite or metal powder in an elastic body such as rubber or resin matrix. There is a method of adjusting the resistance. However, as is well known, in the semiconductive region, the resistance changes sharply with respect to the amount of the conductive filler added, so that the loss and dispersion degree due to the misery to the outside of the conductive filler when the conductive filler is mixed. A slight difference such as the above appears in the change of the electric resistance value, and therefore, lacks reproducibility and has a problem with mass production stability.

In addition, stabilization in the semiconductive resistance region by adding a plasticizer, a low molecular weight liquid rubber, and a surfactant has been proposed. However, when these additives are used, a plasticizer, a low molecular weight liquid rubber, a surfactant, Oozes out on the surface of the charging member, and migrates to the photoreceptor arranged in contact with the charging member, contaminating the photoreceptor, and in some cases causing image defects. In addition, since the plasticizer, the low-molecular-weight liquid rubber, and the surfactant ooze out on the surface of the charging member, the tackiness is remarkably increased. As a result, toner and paper powder are adsorbed, and the function of the charging member is deteriorated. was there.

In addition, there is an example in which a carbon black-containing cross-linked silicone rubber pulverized product as described in JP-A-63-156858 is dispersed in silicone rubber, but in this case, there is a problem that the production cost is increased. is there.

[Problems to be solved by the invention]

The present invention has been made in view of the above points, and has as its object to provide a charging member that is stable in a semiconductive region, has excellent mass productivity, and is inexpensive.

It is another object of the present invention to provide an electrophotographic apparatus capable of forming a good quality copy even after continuous copying of a large number of sheets.

[Means for solving the problem]

 The above object is achieved by the following invention.

That is, the present invention is a charging member characterized in that the elastic body contains a double oxide.

ADVANTAGE OF THE INVENTION According to the charging member containing a double oxide in the elastic body by this invention, it can manufacture stably and with good reproducibility in the semiconductive area | region which was not stabilized conventionally. In addition, by adding a reinforcing agent or a softening agent to the elastic body, a material having an arbitrary resistance value can be stably obtained in the semiconductive region, and at the same time, the elasticity and flexibility can be imparted to the elastic body. When applied to the charging of the photosensitive member, a sufficient nip width is obtained for the photosensitive member, and good charging characteristics are obtained.

The double oxide used in the present invention is a higher-order compound composed of two or more kinds of oxides (a compound formed by intermolecular bonding).
And a metal oxide in which two or more metals coexist. To give an example of a method for producing a complex oxide, one or two or more different kinds of metal ions are dispersed in metal oxide crystal particles and fired in a reducing atmosphere. For example, in the case of a double oxide of zinc oxide and aluminum oxide, zinc oxide and aluminum salt are treated in an aqueous solution of ammonium salt, dehydrated, and then calcined in a hydrogen atmosphere (Japanese Patent Publication No. 62-4117).
No. 1).

Therefore, it is different from a mere metal oxide. Examples of such a complex oxide include a solid solution compound of zinc oxide (ZnO) and aluminum oxide (Al ₂ O ₃ ), and tin oxide (SnO ₂ ).
And antimony oxide (Ab ₂ O ₅₎ a solid solution of the compound and indium oxide (In ₂ O ₃₎ and tin oxide solid solution of (SnO _2), titanium oxide and zinc oxide _{(ZnO) (Ti 2 O 3} ) Solid solution compound, solid solution compound of magnesium oxide (MgO) and aluminum oxide (Al ₂ O ₃ ), and iron oxide (FeO)
And a titanium oxide (TiO ₂ ) solid solution compound.

The characteristics of such multiple oxides cannot be obtained with a single metal oxide because each metal has a close atomic radius, forms a substitution-type solid solution, and has a different valence number. That is, conductivity is obtained.

The specific resistance of these complex oxides is 10 ¹ Ωcm to 10 ³ Ωcm
, And the conductive carbon such loiter and reinforcing carbon black or TiO ₂ and ruthenium oxide (10 ^-2 Ω · cm~10
⁰ Ω · cm) and lower than zinc oxide, aluminum oxide, antimony oxide, indium oxide, triiron tetroxide and tin oxide (at least 10 ⁴ Ω · cm).

That is, 10 ¹ Ωcm to 10 ³ Ωcm of the complex oxide of the present invention.
When a filler is used, stable semiconductivity is obtained with an addition amount that does not cause a problem in physical properties, and excellent reproducibility and mass production stability are obtained.

On the other hand, in the case of a conventional filler dispersed in a dispersion medium such as a polymer, when the specific resistance is less than 10 ¹ Ωcm, the resistance value rapidly changes with respect to the amount of the filler added as described above. Since it corresponds to an area, it lacks reproducibility and mass production stability.

On the other hand, when the resistivity is higher than 10 ³ Ω · cm, a considerably large amount of addition is required in order to develop semiconductivity, and dispersion processing becomes difficult. Even if dispersed, the physical properties are remarkably inferior to the practical level. In addition, the hardness is considerably increased, and there arises a problem that a sufficient and stable pressure-contact state cannot be obtained with respect to the photosensitive member or the like.

Of the multiple oxides, ZnO.Al ₂ O ₃ is particularly excellent. The reason is that the specific resistance of this filler is 10 ² Ω
・ Cm ~ 10 ³ Ω ・ cm
The most ideal resistance value, easy dispersion and excellent workability in a polymer dispersion medium such as resin or rubber, low cost, doping amount of Al (Al ₂ O ₃ ) To achieve an appropriate resistance value.

The content of the double oxide in the elastic body is preferably 5 wt% to 40 wt%, particularly preferably 10 wt% to 30 wt%.

Further, when a transfer material such as paper is also transported, as typified by a roller-shaped transfer charging member, the material itself needs to have mechanical strength such as abrasion resistance.

In this case, a reinforcing agent is preferably used in addition to the double oxide.

As the reinforcing agent, reinforcing carbon such as carbon black, silica or the like can be appropriately used. Results we have examined the case of using carbon black as the specific resistance 10 ⁰ Ω · cm or more, 0.1 wt% The addition amount 20
It has been found that the reinforcing property is excellent and the resistance is stable in the range of wt%, preferably in the range of 1 wt% to 15 wt%. That is, the specific resistance is 10 ⁰ Omega · conductive capacity is large is less than cm, prone to potential non-uniformity in a small amount of addition. On the other hand, if the addition amount exceeds 20% by weight, the dependence of the resistance value on the carbon black is greater than that of the composite oxide, and the addition of the composite oxide tends to become meaningless.

As the reinforcing carbon, those used for general industry, for example, ISAF (Inter-mediate Super Abrasio)
n Furnace), SAF (Super Ab-rasion Furnace), H
AF (high abrasion furnace black), FEF (F
ast Extrusion Fur-nace), SRF (Semi-Reinforcin)
g Furnace), FT (Fine Thermal), EPC (Easy Proc)
essing Channel), MPC (Medium Processing Channe)
l) and the like.

Also, a charging member for roller shape transfer or a roller shape 1
By maintaining a sufficient pressure contact area with the photoreceptor in the charging member for the next charging, good charging characteristics and transfer characteristics without unevenness can be obtained. Therefore, low hardness is particularly required for the above-mentioned applications.

At this time, preferably, process oil such as insulating oil is added, but as a result of studying various insulating oils, the specific resistance is 10 ¹² Ωcm or more, and the added amount is 5 watts.
At t% to 20% by weight, preferably 8% to 16% by weight, the hardness is low, the reinforcing property is excellent, and the resistance value is stable. If oil with a specific resistance of less than 10 ¹² Ωcm is used, the potential on the photoconductor will be displaced at the oil transfer point when it moves onto the photoconductor, causing image failure or toner aggregation on the photoconductor Tend to. On the other hand, if the addition amount exceeds 20% by weight, bleeding to the surface of the charging member becomes remarkable, contaminating the photoreceptor, and toner and paper powder adhere to the surface of the charging member significantly. A problem of deterioration is 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, SBR (styrene butadiene rubber), CR (chloroprene rubber), NBR (nitrile butadiene rubber), Rubber such as silicone rubber, urethane rubber, epichlorohydrin rubber, and thermoplastic such as polystyrene, polyolefin, polyester, polyurethane, and PVC such as RB (butadiene resin) and SBS (styrene-butadiene-styrene elastomer) Elastomer, polyurethane, polystyrene, PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), acrylic resin, styrene-vinyl acetate copolymer, butadiene-acrylonitrile copolymer and other high polymer materials Can be used. The elastic body can be used as a foam or as a solid rubber.

Further, if necessary, calcium carbonate, various clays, talc or the like or a blend thereof, or a filler such as silica-based filler such as hydrous silicic acid, silicic anhydride and respective salts may be added. Good.

When a foaming agent is used, the foaming agent may be ADC
A. (azodicarbonamide) type, DPT (di-nitrosopentamethylenetetramine) type, OBSH (4.4'-oxybis-benzenesulfonyl-hydrazide) type, TS
H. (P-triensulfonyl hydrazide) system, AIB
N. (azobisisobutyronitrile) type etc. can be used, especially for ADCA type and OBSH type blend type, it is a dense foam and vulcanized tight (high crosslink density)
A good foam is obtained.

In the case of polymers that can change the strength and flexibility of the material by adjusting the polymer structure of the polymer itself as seen in certain types of polymers such as urethane rubber and silicone rubber, it is only necessary to add a double oxide, Hardness and strength required for practical use can be achieved without necessarily adding a reinforcing filler such as carbon black or a softening agent.

The specific resistance of the powder in the present invention is 100 K
It was measured by a general powder resistance measurement method at 25 ° C. and 60 RH% at g / cm ² .

The shape of the charging member of the present invention may be any of a roller, a blade and the like, and can be selected according to the specification form of the electrophotographic apparatus.

FIG. 1 shows the basic configuration of a roller-shaped charging member 1. In this case, an elastic body 3 containing a double oxide is formed on a cylindrical conductive substrate 2. Further, the charging member is
In the case of a blade shape, 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, and stainless steel, metal alloys, conductive resins, and the like can be used.

Using the charging member of the present invention, for example, when charging the photoreceptor, by applying a voltage from the outside to the conductive substrate of the charging member, the photoreceptor is disposed in contact with the charging member Charging can be performed.

Charging is performed by bringing a charging member into contact with the surface of the photoreceptor, and the surface of the photoreceptor is charged by the charging member to which a voltage is applied. This is because discharge is performed through a light wedge-shaped space outside the contact portion between the body and the charging member. The reason why the charging member is brought into contact with the photoconductor is to form such a minute gap. That is, the small gap is maintained by the contact of the charging member with the photoconductor.

The charging member of the present invention can be used for transfer, primary charging, charge elimination, and also for conveyance such as a paper feed roller. There is a problem that the roller contact portion of the transfer material is charged by friction between the transfer roller and the transfer material, resulting in uneven charging of the transfer material itself, resulting in image unevenness, and as a means for solving this problem, this material is used. Applicable.

OPC is a photosensitive member that can use the charging member of the present invention.
(Organic photoconductor) Various photoconductors such as photoconductor and A-Si, Se, ZnO can be used. In particular, by using the charging member of the present invention for an OPC photosensitive member that is easily deteriorated in terms of mechanical strength and chemical stability, its characteristics can be remarkably exhibited.

Examples of the electrophotographic apparatus that can use the charging member of the present invention include a copier, a laser beam printer, an LED printer, and an electrophotographic application device such as an electrophotographic plate making system.

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

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

As an electrophotographic apparatus, a plurality of components, such as the above-described photoconductor, developing means, and cleaner, are integrally connected as an apparatus unit, and the unit is configured to be detachable from the apparatus body. Is also good. For example, the photoconductor 4 and the cleaner 8 may be integrated into one device unit, and may be configured to be detachable using a guide unit such as a rail of the device body. At this time, the above-mentioned device unit may be provided with charging means and / or developing means.

In the case of using an electrophotographic apparatus as a copying machine or a printer, light image exposure is a process of reflecting or transmitting light from a document, or reading a document and converting the signal into a signal. , Or by driving a liquid crystal shutter array.

When used as a facsimile printer, light 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 unit 10 and the printer 19. The entire controller 11 is controlled by the CPU 17. The read data from the image reading unit is transmitted to the partner station through the transmission 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. The printer controller 18 controls the printer 19. 14 is a telephone.

The image received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, and then the CPU 17 performs a decoding process of the image information, and is sequentially stored in the image memory 16. You. When the image of at least one page is stored in the memory 16, the image of the page is recorded. The CPU 17 reads out one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. The printer controller 18
Upon receiving one page of image information from the CPU 17, the printer 19 is controlled to record image information of the page.

Note that the CPU 17 is receiving the next page during recording by the printer 19. As described above, image reception and recording are performed.

Example 1 100 parts by weight (hereinafter referred to as "parts") of EPDM (EPT4045 Mitsui Petrochemical) was used as a dispersant polymer, 10 parts of zinc white 1 and 2 parts of stearic acid, and a promoter M (Noxeller M Ouchi Shinko Chemical) 2
Parts, Accelerator BZ (Noxeller BZ Ouchi Shinko Chemical) 1 part, Sulfur 2 parts, Blowing agent (Celmic C Sankyo Kasei) 5 parts, Foaming aid (Celton NP Sankyo Chemical) 5 parts, and reinforcement and insulation Oil and other components are blended according to the respective blending compositions based on Table 1, and the rubber is wound around a core made of iron that has been uniformly dispersed and kneaded using a two-roller and is provided with a primer.
Preform at 40 ° C. and 100 kgf / cm ^2, vulcanized by steam vulcanization (160 ° C., 30 minutes), and then polished to produce roller-shaped charging members A to E. The dimensions are core diameter 6mm, outer diameter 16mm, core length 250mm, rubber length 23
It was 0 mm. Resistance measurement is 1kg in total 500g at both ends on Al plate
And the resistance between the cored bar and the Al plate was measured (23 ° C.,
50RH).

FIG. 4 shows the relationship between the resistance value of each charging member obtained in this way and the number of added parts of each filler (based on 100 parts by weight of rubber).

As is apparent from FIG. 4, by adding the ZnO.Al ₂ O ₃ double oxide in a predetermined semiconductive region, the resistance fluctuation is small with respect to the change of the added amount, and the oxide semiconductor can be stabilized.

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

In addition, when a reproducibility test of the resistance value was performed for each formulation,
12ph in case of conductive carbon (etch black EC)
In the r addition, a variation of 3 orders in the range (5 × 10 ¹⁰ Ω to 5 × 10 ⁷ Ω) was generated with respect to 10 ⁹ Ω. On the other hand, it was found that the range of the ZnO.Al ₂ O ₃ composite oxide was within the order of 1/4 (measured value × 1.125 to measured value × 0.875), which was about the measurement error range. Further, the charging member E
Regarding the above, a desired semiconductive region cannot be realized even if the amount of Fe ₃ O ₄ added is changed within a general range.

Example 2 100 parts of EPDM (EPT4045 Mitsui Petrochemical), Zinhua No. 1 10
Parts, stearic acid 2 parts, ZnO.Al ₂ O ₃ 100 parts, accelerator M
(Noxeller M Ouchi Shinko Chemical) 2 parts, Accelerator BZ (Noxeller BZ Ouchi Shinko Chemical) 1 part, sulfur 2 parts, foaming agent (Celmic C Sankyo Chemical) 5 parts, foaming aid (Celton NP Sankyo Chemical) A roller-shaped charging member 1 was prepared by the same manufacturing method as described above with a composition of 5 parts, 45 parts of HAF carbon as a reinforcing agent, and 60 parts of paraffin oil as an insulating oil.

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

Further, a roller-shaped charging member 3 was prepared with the same composition as that of the charging member 1 except that 45 pieces of HAF carbon and 55 parts of paraffin oil were used.

The primary vulcanization (250 ° C., 20 ° C.) was carried out using a composition of 150 parts of ZnO · Al ₂ O ₃ , 100 parts of silicone rubber (KE520 Shin-Etsu Chemical), 2 parts of a silicon crosslinking agent (C8 Shin-Etsu Chemical) and 1.5 parts of AIBN. Minutes)
Further, secondary vulcanization (200 ° C., 4 hours) was performed to prepare a roller-shaped charging member 4.

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 In ₂ O ₃ .SnO ₂ was used.

Also, 20 parts of HAF carbon and 70 parts of paraffin oil
, And a roller-shaped charging member 6 was produced in the same manner as the charging member A, except that 20 parts of the toner black EC were used.

Also, a roller-shaped charging member 7 was produced in the same manner as the roller-shaped charging member E except that 100 parts 7 of Fe ₃ O ₄ were used.

The roller-shaped charging members 1 to 7 thus manufactured
Table 2 shows the hardness and electric resistance of the sample.

Further, roller-shaped charging members 1 to 7 were mounted as charging members for transfer of an electrophotographic apparatus (laser beam printer), and image evaluation was performed using the electrophotographic apparatus shown in FIG.

This device uses a φ40mm OPC drum and has a dark area potential (V
_D ) was set to -600 V, the light potential ( _VL ) was set to -100 V, and reversal development was performed using a one-component insulating magnetic toner. Copy paper having a basis weight of 64 g / m ² was used as the transfer material. The paper feed speed was 40 mm / sec.

 The configuration of the OPC drum is as follows.

An aluminum cylinder having a thickness of 0.5 mm and a diameter of 40 mm × 260 mm was prepared as a substrate.

Copolymer nylon (trade name: CM8000, manufactured by Toray Industries, Inc.) 4
Part and type 8 nylon (Product name: Ratsukamide 500
3, Dainippon Ink Co., Ltd.) 4 parts methanol 50 parts, n
-Dissolved in 50 parts of butanol, dipped and coated on 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 (Esrec BM2, manufactured by Sekisui Chemical) were dispersed together with 120 parts of cyclohexanone in a sand mill for 10 hours. 30 parts of methyl ethyl ketone was added to the dispersion, and the dispersion was coated on the undercoat layer to form a 0.15 μm thick charge generation layer.

Polycarbonate Z resin (Mitsubishi Gas Chemical Co., Ltd.)
10 parts of a weight average molecular weight of 120,000 were prepared, and monochlorobenzene 80 was added together with 10 parts of a hydrazone compound having the following structural formula.
Dissolves in the part.

This was applied on the charge generation layer to form a charge transport layer having a thickness of 18 μm, thereby forming an OPC drum.

The charging roller 5 has a conductive rubber layer provided on a cored bar, and a roller made of conductive urethane rubber of 10 ⁶ Ω was used. Here, the resistance represents the resistance from the core metal to the roller surface per 1 cm ^{2 of the} roller surface. The charging roller 5 is constantly pressed against the surface of the OPC drum 4 with a predetermined pressure (for example, a linear pressure of 0.01 to 0.2 kg / cm), and uniformly charges the photoconductor by applying a predetermined voltage. . In this embodiment, the charging roller is shown as the charging means, but a corona charger conventionally used may be applied.

Example 3 CR rubber (WM-1 Showa Neoprene Co., Ltd. 100 parts by weight (hereinafter simply referred to as "parts") MgO (Kyowa Mag 150) 4 parts Ketchien Black EC 9 parts Circo Light.RPO (Nippon Sun Oil) 30 parts NEO ACTIS-N ( Tenma Sub Chemical Co., Ltd. 20 parts Paraffin in Watts (Mobile Oil) 2 parts CML # 21 (Omi Chemical) 2 parts ZnO1 5 parts Accelerator 22S (Kawaguchi Chemical) 1.6 parts Accelerator BUR 2 parts Cell Mic C 8 parts Celton NP ( Sankyo Chemical Co., Ltd. 4 parts Blended with the above composition, uniformly dispersed and kneaded using two rolls, wrapped rubber around iron core bar coated with primer, put into mold, 40 ° C, 100Kgf / cm Preform at ² and vulcanize it by steam vulcanization (150 ° C, 30 minutes)
Thereafter, the base elastic layer was produced by polishing.
At this time, the core diameter is 6 mm, the outer diameter is 11 mm, the core length is 250 mm,
The rubber length was 240 mm.

Next, 100 parts of EPDM rubber (EPT4045 Mitsui Petrochemical), 10 parts of Zinhua No. 1, 2 parts of stearic acid, 2 parts of accelerator M, 1 part of accelerator BZ1
Parts, sulfur 2 parts, paraffin oil 60 parts, HAF carbon 4
5 parts, 100 parts of ZnO / Al ₂ O ₃ were blended, uniformly dispersed and kneaded using two rolls, coated with the above-mentioned CR sponge roller with a crosshead extruder, preformed and re-formed. Vulcanization was performed at 160 ° C. for 30 minutes with steam vulcanization, followed by polishing to prepare a roller-shaped charging member. The dimensions of the completed roller-shaped charging member are 12 mm in outer diameter,
The rubber length was 230 mm. Roller resistance at this time is 5th
In the method shown in the figure, an aluminum foil 21 having a width of 10 mm is wound on a charging roller base layer 20, a current of 1 KV is applied between the core metal and the aluminum foil by a power supply 22, and a current is measured. When measured by a method for obtaining a resistance value, it was 4 × 10 ⁷ Ω · cm (25
° C, 60% RH).

This roller was used as the charging roller 5 in FIG. 2, and the transfer roller used was the No. 1 roller of Example 2. The voltage was applied to the charging roller 5 at an AC frequency of 150 Hz, an AC peak-to-peak voltage of 2 KV; and a DC voltage of 700 V. The same image quality as in the initial stage was obtained even after 100,000 sheets of durability.

Also, make a pinhole with a diameter of about 0.5mm on the OPC drum photoreceptor, 150 ℃, 10% RH, 250 ℃, 50% RH, 32.5 ℃, 85% RH
Image evaluation was performed in the same manner under each environment.
The surface layer and the underlying elastic layer of the environmentally-charged roller did not suffer from electrical breakdown, and a sufficient charging potential required for charging was obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view (left figure) and a parallel sectional view (right figure) of the charging member of the present invention in the axial direction, and FIG. 2 is a schematic sectional view of an electrophotographic apparatus used in the present embodiment. FIG. 4 is a block diagram of a facsimile using the electrophotographic apparatus according to the present invention as a printer. FIG. 4 is a graph showing the relationship between the additive amount of the additive and the resistance of the charging member. FIG. DESCRIPTION OF SYMBOLS 1 ... Charging member 2 ... Conductive substrate 3 ... Elastic body

Claims (16)

(57) [Claims] 1. A charging member characterized in that a double oxide is contained in an elastic body. 2. The method 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. Charging member. 3. The content of the double oxide in the elastic body is 5 to 40% by weight.
The charging member according to claim 1, wherein the charging member is: 4. The charging member according to claim 1, wherein a reinforcing agent is contained in the elastic body. 5. The charging member according to claim 4, wherein the reinforcing agent is a carbon black. 6. The charging member according to claim 1, wherein the elastic body contains an insulating oil. 7. The charging member according to claim 1, wherein the elastic body contains a double oxide, 0.1 wt% to 20 wt% carbon black, and 5 wt% to 20 wt% insulating oil. . 8. The charging member according to claim 7, wherein said 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 in contact with the surface of the electrophotographic photoreceptor. 10. The electrophotographic apparatus according to claim 9, wherein the charging member is arranged at a position where the toner image formed on the surface of the electrophotographic photosensitive member is transferred to a transfer material. 11. An electrophotographic apparatus according to claim 9, wherein said charging member is arranged at a position for uniformly charging said electrophotographic photosensitive member. 12. The method 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. Electrophotographic equipment. 13. An oxide having a multiple oxide content of 0.1 wt% to 20 wt%.
13. The electrophotographic apparatus according to claim 12, wherein the electrophotographic apparatus contains carbon black and 5 to 20% by weight of an insulating oil. 14. The electrophotographic apparatus according to claim 13, wherein said double oxide is a solid solution of zinc oxide and aluminum oxide. 15. An electrophotographic apparatus having an electrophotographic photosensitive member and a charging member abutting on the surface of the electrophotographic photosensitive member and containing a double oxide in an elastic body, and receiving image information from a remote terminal. A facsimile characterized by having means. 16. The method 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. Facsimile.