JP3535789B2 - Conductive elastic body and image forming apparatus using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive elastic body, and more particularly to a conductive elastic body which is used by contacting an image carrier in an image forming apparatus such as a copying machine or a laser printer which employs an electrophotographic method. And an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, a corona charging method has been adopted in which a high voltage is applied to a metal wire, and a photoconductor is charged or transferred by a corona generated. However, in the corona charge method, corona products such as ozone and NOx change the surface of the photoconductor when corona is generated. Therefore, in addition to image quality such as white spots and black streaks in the image, the office environment is also considered. Also had a problem. Therefore, as a method that does not generate ozone, NOx, etc., an image forming method has been proposed in which a conductive elastic body is brought into contact with a photoconductor or the like to be charged and transferred.

For example, in an electrophotographic image forming apparatus, as a means for transferring a toner image formed on an image bearing member to a transfer material, a conductive elastic body attached opposite to the image bearing member is used. There is a process of performing contact transfer by applying a voltage of about several hundred V to 2 kV from the back side of the transfer material. For the conductive elastic body used in this image forming method,
The required characteristics and problems are described below.

It is required that the volume resistivity of the conductive elastic body partially varies little, and that the variation in electric resistance between lots when mass-produced at the tens of thousands lot level is small. Normally, assuming that the setting value is 10 ⁸ Ω · cm, the variation width of the resistance is within about 0.8 digit depending on the conditions of the machine used. This is because if the resistance variation is large, image deterioration such as transfer unevenness and transfer failure may occur depending on environmental conditions. Therefore, the smaller the variation amount is, the better. However, by tightening this regulation, the conductive elastic body This is because the yield and the like have a great influence. In particular, in the case of a non-polar rubber such as EPDM (ethylene-propylene-diene copolymer rubber) filled with carbon black as a conductive filler, partial resistance variation is likely to occur depending on the dispersion state. This is because the conductive filler carbon black has a large average particle size of 10 μm, and it is very difficult to disperse the carbon black evenly when mixed in the base rubber. The reason is that On the other hand, when urethane rubber or the like is filled with an ion conductive filler as a resistance adjusting agent, the phenomenon in which the electric resistance varies depending on the position (hereinafter, referred to as electric resistance position variation) is small.

It is required to reduce the fluctuation of the volume resistivity with respect to environmental changes. If the fluctuation of the volume resistivity is large, problems such as poor transfer efficiency, reverse transfer, uneven transfer and abnormal discharge occur. Usually, in a low temperature and low humidity (5 ° C. 20%, abbreviated as LL hereinafter) environment, the volume resistivity increases, and even if the applied voltage is increased, the transfer current does not flow and the transfer efficiency deteriorates. In addition, high temperature and high humidity (35 ℃ 85
%, Hereinafter referred to as HH), the resistivity of the conductive elastic body and the transfer material becomes low, an abnormal discharge phenomenon occurs through the surface of the paper or the surface of the housing (insulator), and the current flows to the conductive elastic body. Does not flow, and good transferability cannot be obtained, and the image quality deteriorates. Regarding this environmental change, the smaller it is, the better, but at present, if the set value is 10 ⁸ Ω · cm, it is currently about 1 to 2 digits for urethane rubber etc. filled with ion conductive filler as a resistance adjusting agent. The degree is EP
A non-polar rubber such as DM filled with carbon black or the like as a resistance adjusting agent has little dependency. If the resistivity changes due to the environmental change, it is necessary to detect each environmental condition and change the transfer bias according to the detected environment.

It is required that the electric resistance has little dependency on the applied voltage. Prevents overcurrent in the non-paper-passage area and shortage of transfer current in the paper-passage area when passing small size paper,
As a result, it is intended to prevent transfer failure on small size paper. Particularly in a conductive elastic body in which a non-polar rubber such as EPDM is filled with carbon black or the like as a resistance adjusting agent,
The voltage dependency is large, and that in which urethane rubber or the like is filled with an ion conductive filler as a resistance adjusting agent has little dependency.

It is required that the fluctuation range of the electric resistance due to the continuous voltage application in the continuous paper feeding is small. This is a phenomenon in which the volume resistivity increases due to continuous application of a transfer voltage during continuous paper feeding, and especially when the base rubber is filled with an ionic conductive filler as a conductive filler. It is noticeable when it is present. The reason for this is that the salt added for expressing conductivity inside the base rubber dissociates and polarizes, and is electrically separated near the intermediate layer, resulting in a high resistance value. It is possible. When the resistance value becomes high, a predetermined transfer current cannot be secured, so that transfer failure occurs.

Further, it is demanded for all conductive elastic bodies that toner releasability, abrasion resistance and durability are excellent, and that recycling is facilitated from the viewpoint of environmental problems. . The residual toner remaining on the image carrier is transferred to the conductive elastic body and is contaminated by long-term use. This causes problems such as transfer failure, back stain, and increase in volume resistance of the conductive elastic body. Therefore, it is necessary to clean the residual toner transferred to the conductive elastic body,
In that case, a method of cleaning the surface of the conductive elastic body with a blade, a fur brush or the like, a method of returning the toner onto the image carrier by applying a predetermined voltage, and the like have been devised. At present, the foamed elastic body that constitutes the conductive elastic body is an organic polymer, and it is difficult to return it to the raw material for recycling.

As described above, the conductive elastic body is required to have many performances, but the current conductive elastic body has many problems. In particular, in the case of using a conventional conductive elastic body, that is, those in which urethane rubber is filled with an ion conductive filler, EPDM, silicone rubber in which carbon black and metal oxides are filled have advantages and disadvantages. The problem has been solved by electrically controlling the bias applied to the conductive elastic body or performing complicated control.

At present, commercially available conductive elastic bodies are roughly classified into those obtained by filling a polyurethane foam with an ion conductive filler as a conductivity-imparting agent, and EP.
Some DM and silicone rubber foams are filled with carbon and a metal oxide as a conductivity-imparting agent, but it cannot be said that sufficient performance is obtained in any of them.

In recent years, in order to solve the above-mentioned problems, technical development has been carried out in which the material surface of the conductive elastic body has various characteristics. For example, Japanese Patent Laid-Open No. 10-221980 discloses a conductive material. To obtain a conductive elastic body by mixing a conductivity-imparting agent composed of a quaternary ammonium salt in a polyurethane foam obtained by using a polyester polyol as a polyol component, and then heating and curing the mixture to effect reaction curing. There is disclosed a technique for reducing the position variation of the electric resistance related to the conductive elastic body, and reducing the dependence of the electric resistance on the applied voltage, the electric resistance fluctuation width during continuous energization, and the electric resistance fluctuation due to environmental changes.

[0012]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, according to the description of the above publication, the position variation of the electric resistance of the conductive elastic body is reduced, the applied voltage dependency of the electric resistance, and It is possible to reduce fluctuations in electric resistance and fluctuations in electric resistance due to environmental changes.

However, regarding the conductive elastic body described in the above publication, when the resistance value variation under each environmental condition is examined, in the case where the environmental variation is 15 ° C. 10% and 32.5 ° C. 85%, the resistance variation is the smallest. The resistance value has changed by about two digits. If the resistance change is about 2 digits, good transfer cannot be performed unless the voltage applied to the conductive elastic body is changed for each environment. Therefore, each environmental condition is detected and transfer is performed according to the detected environment. Complex control such as changing the bias must be performed.

Further, the upper limit value of the environmental fluctuation in the example of this publication is 3.8 × 10 ⁹ Ω, and in the experiment of the present inventor, the resistance is too high in this resistance region, so that a satisfactory transfer current is obtained. Was not obtained, and it was found that the transfer efficiency was lowered and the transfer became defective.

The present invention has been made in order to solve the above-mentioned conventional problems, and its purpose is to change the environment, change in volume resistivity due to applied voltage, position variation in electrical resistance, and continuous. A conductive elastic body suitable for charging, developing, and transferring means that reduces fluctuations in electrical resistance when energized, has excellent toner releasability, abrasion resistance, and durability, and not only improves image quality, but also facilitates recycling. And to provide an image forming apparatus using the same.

[0016]

A conductive elastic body according to the present invention for solving the above-mentioned problems includes a base portion made of a core body and an elastic portion made of an elastic body covering the base portion and having conductivity. And a conductive elastic body having at least a three-layer structure composed of a surface layer part having conductivity and covering the elastic part, wherein the conductive filler mixed to add conductivity to the elastic part is an average Particle size 5μm or less, dielectric constant 300 or more
Ceramics fine powder , further, as the ceramics fine powder, a sintered compact fine powder composed of two or more compounds is used, and one compound of the sintered compact fine powder contains titanium oxide, The surface portion is characterized in that a non-polar flexible synthetic resin tube is coated on the surface of the conductive portion by a contracting action.

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

In addition, the conductive elastic body having the above-mentioned structure
Then, the thickness of the surface portion is set to 30 μm to 250 μm.
It

A device using the conductive elastic body having the above structure
As a device, a charging means for contact-charging the surface of the image carrier,
Of the developing means for supplying a developer to the electrostatic latent image formed on the surface of the image carrier to visualize it, and the transfer means for transferring the visualized image formed on the image carrier to a recording medium. An image forming apparatus characterized by being used for at least one.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The following will describe one embodiment of the present invention. The device including the conductive elastic body according to the exemplary embodiment of the present invention is not particularly limited, but the following description will be given of an example in which the conductive elastic body is applied to the image forming apparatus. Further, as the image forming apparatus, various image forming principles such as the Carlson process and the back exposure method can be used for the image forming method on the image carrier required for recording an image on the image forming body, It is not limited. In the embodiments of the present invention described below, an image forming apparatus using the Carlson process will be described as an example.

FIG. 4 is a schematic sectional view of the image forming apparatus 100 according to the embodiment of the present invention. The image forming apparatus 100 is
For example, it is generally used as an output device (printer) of an information processing device such as a computer, but other than this, it can also be used as a printing unit of a word processor, a FAX (facsimile), or a printing unit of a digital copying machine. .

The image forming apparatus 100 is mainly composed of an image forming section 10 for forming an image and a sheet feeding apparatus 30 for supplying a sheet (transfer material) P to the image forming section 10.
The image forming section 10 includes a photosensitive drum 11 as an image carrier having a photosensitive layer arranged on an aluminum tube, and a charging device 12 and an exposure device (laser) which are provided around the photosensitive drum 11 in this order. Unit) 13, developing device 14, transfer device 15,
A neutralization device (static elimination lamp) 16 and a fixing device 17 are provided.

The charging device 12 includes a charging conductive member (charging means) 18 for applying a uniform charge to the surface of the photosensitive drum 11, and a charging power source 19 for supplying a potential to the charging conductive member 18. It has and. The laser unit 13 irradiates the charged surface of the photosensitive drum 11 with a laser in accordance with image data, and forms an electrostatic latent image formed of a charge pattern on the photosensitive drum 11.

The developing device 14 supplies a toner 50, which is a developer, to the electrostatic latent image formed by the exposure of the laser unit 13 to form a toner image, that is, a developing conductive member (developing means). ) 21 and a developing power source 22 for supplying a developing voltage to the developing conductive member 21.

The transfer device 15 transfers the paper P to the photosensitive drum 1
A transfer conductive member (transfer means) 23 for pressing the toner image formed on the photosensitive drum 11 onto the sheet P and transferring the toner image to the sheet P;
A transfer power source 24 that supplies a transfer voltage to the transfer conductive member 23 at the time of transfer is provided.

The static elimination lamp 16 includes a plurality of LEDs (Light Emitt
ing diode), the surface of the photoconductor drum 11 is irradiated with light to neutralize and eliminate the electric charge remaining on the surface of the photoconductor drum 11.

The paper feeding device 30 includes a cassette 31 for containing the paper P, a pickup roller 32 for feeding the paper P from the cassette 31, a paper feed guide 33 for guiding the supplied paper P, and a paper P fed. Is composed of a pair of registration rollers 34 that convey the sheet at a predetermined speed. Further, the paper feeding device 30
Includes a paper feed sensor (not shown) that detects that the paper P has been fed.

The pickup roller 32, the charging conductive member 18, the developing conductive member 21, the transfer conductive member 23, and the photosensitive drum 11 are rotationally driven by a driving device (not shown). These rotary drives are appropriately controlled at a predetermined timing by a control means (not shown). A paper output roller 41 for discharging the paper P out of the apparatus and a paper discharge tray 42 for holding the discharged paper P are arranged on the paper output side of the image forming unit 10.

In the image forming apparatus 100 having the above structure,
The conductive elastic body according to the present invention can be preferably used for at least one conductive member of the charging conductive member 18, the developing conductive member 21, and the transfer conductive member 23.

Although the conductive elastic body is shown in FIG. 4 as having a roller shape, the present invention is not limited to this and may be an endless belt shape. Since the conductive elastic body has an endless belt shape, when used as a transfer belt, for example, a high image quality can be realized due to the merit that a large nip width can be obtained, and in the case of a color, a multiple transfer method can be used. Can be used in a tandem system with a fast process speed. Further, since the transfer material is transported together with the transfer belt, it is possible to realize proper transport of the transfer material.

A roller-shaped conductive elastic body according to an embodiment of the present invention has a structure as shown in FIGS. That is, the base body 1 constituting the base body portion is a so-called "core bar" made of iron, aluminum, SUS, brass or the like, and a core body made of a thermoplastic resin or a thermosetting resin and its surface are plated. , A core formed of a conductive resin molded product in which a conductive carbon black or a metal powder as a conductivity-imparting agent is mixed with a thermoplastic resin or a thermosetting resin, or a core made of a combination thereof. An elastic body 2 which is made of an arbitrary material selected from the group consisting of plastic, metal, and ceramic materials, and whose main material is ethylene-propylene-diene copolymer rubber (EPDM), which is a nonpolar rubber coated on the substrate 1. The surface layer portion (the portion that comes into contact with the image carrier) is covered with a flexible synthetic resin 3 such as non-polar polyethylene resin having conductivity.

If the conductive elastic body has an endless roller shape, for example, when it is used as a transfer roller, it is possible to facilitate pressure contact with the opposing member (OPC) and obtain a nip width sufficient for transfer. It is possible to obtain a high quality image. Further, since the opposing member (OPC) and the transfer roller press-contact the transfer material, it is possible to realize proper transfer of the transfer material.

On the other hand, in the case of having a blade shape, FIG.
As shown in FIG. 1, the base body 1, the elastic body 2, and the flexible synthetic resin 3 have a flat plate shape. As a result, when used as a transfer blade, for example, the toner scattering at the upstream portion of the transfer portion is smaller than that of the transfer roller, and the opposing member (OP
The volume of the conductive elastic body that obtains the same nip width as that of C) is small, and the structure is simple, and it can be manufactured at low cost without requiring special manufacturing technology.

As will be described later, since the substrate forming the elastic body is EPDM, the substrate forming the elastic body does not change in volume resistivity due to environmental changes, and the elastic body is made electrically conductive. By selecting a conductive filler to be mixed in for addition, it is possible to obtain a conductive elastic body that hardly causes volume resistivity fluctuation due to environmental changes. If there is no change in resistivity due to environmental changes,
It is not necessary to detect each environmental condition and change the transfer bias according to the detected environment.

Further, by having at least one layer of the above-mentioned conductive elastic body on the base body, the conductive elastic body can be supported by the base body without increasing the hardness of the conductive elastic body. In this case, it is possible to prevent pressure loss due to time-related fatigue and the like, and prevent the endurance life from being shortened, which facilitates design and mass production. Here, the elastic body 2 and the flexible synthetic resin 3 are mixed with a ceramic fine powder 4 which is a conductive filler to achieve a medium resistance and a resistance value adjustment.

The reason why the flexible synthetic resin is provided on the surface layer of the conductive elastic body is that even if the flexible synthetic resin is not provided, environmental changes, changes in volume resistivity due to applied voltage, and The electrical characteristics such as the position variation of the electric resistance and the fluctuation of the electric resistance during continuous energization are sufficient, but by providing a flexible synthetic resin, abrasion of the conductive elastic body due to the abrasion load with the pressure contact member is provided. To prevent problems such as deterioration, change in composition of base rubber, change in volume resistivity of conductive elastic body due to mixing of impurities, contamination of pressure contact member due to the conductive elastic body, and further improvement of releasability of toner. This makes it easier to clean and increases the strength of the conductive elastic body, which makes it possible to realize a long life. Further, when the conductive elastic body is used as the transfer means, the image quality is improved. Also effective But also because it brings. Furthermore, when the conductive elastic body is reused, the flexible synthetic resin, which is the coating layer, is peeled off and a new flexible synthetic resin is coated so that it can be reused, which is environmentally friendly and can be recycled. It is also for ease.

As the elastic body 2, nitrile butadiene rubber, chloroprene rubber, fluororubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber,
Polar elastomer such as norbornene rubber, polystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-maleic acid copolymer, low molecular weight polyethylene, low molecular weight polypropylene, phenol resin, silicone resin, xylene resin , And non-polar resins such as copolymers and mixtures thereof, chloropolystyrene, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer Polymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene -Methyl methacrylate co-polymer Styrene resin such as styrene, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer ( Styrene or styrene-substituted homopolymer or copolymer), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, epoxy resin, polyester resin, ionomer resin, polyurethane resin, ketone resin, ethylene −
Polar resins such as ethyl acrylate copolymers, fluororesins, polycarbonates, polyamide resins, ribinyl butyral resins and copolymers and mixtures thereof are also possible, but more preferably the volume resistivity variation due to environmental changes From the viewpoint of suppressing effect and lowering hardness, ethylene-propylene diene polymer (EPDM), butadiene rubber, styrene-
Most preferred are non-polar elastomers such as butadiene rubber (SBR), high styrene rubber, isoprene rubber, butyl rubber, silicone rubber and natural rubber (NR).

On the other hand, examples of the flexible synthetic resin 3 include chloropolystyrene, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylic ester copolymer (styrene-methyl acrylate copolymer). , Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene- Methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic ester copolymer, etc. Styrenic resin (including styrene or styrene substitution products) Homopolymer or copolymer), vinyl chloride resin, styrene - vinyl acetate copolymer, rosin-modified maleic acid resins, epoxy resins, polyester resins,
Polar resins such as ionomer resins, polyurethane resins, ketone resins, ethylene-ethyl acrylate copolymers, fluororesins, polycarbonates, polyamide resins, livinyl butyral resins and their copolymers and mixtures are also possible, but more preferable. Include polystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-maleic acid copolymer, low-molecular-weight polyethylene, low-molecular-weight polypropylene, and phenol resin from the effect of suppressing volume resistivity fluctuations due to environmental changes. Most preferred are non-polar resins such as silicone resins, xylene resins, and copolymers and mixtures thereof.

Further, as the ceramic fine powder 4, Si is used.
O₂, MgO, Al₂O₃, CaO, PbO, Fe₂O₃, BaO, TiO₂, ZnO, Z
rO₂, SrO, Li₂Mullite and colander consisting of O and other ingredients
Mu, cristobalite, sapphirine, cordierai
G, forsterite, spinel, barium titanate
(BaTiO₃), Magnesium titanate (MgTiO₃),Titanium
Calcium acid (CaTiO₃), Strontium titanate (Sr
TiO₃), Lanthanum titanate, zinc titanate, vinyl titanate
Sumus, PbTiO₃, KnbO₃, MgTiO₃-CaTiO₃, BaO ・ 4TiO
₂-TiO₂2MgO ・ SiO₂-SrO-BaO-TiO₃, BaTiO₃-Nd₂O₃-TiO
₃, PbTiO₃-PbZrO ₃, BaTiO₃-SrTiO₃-La₂O₃-TiO₂, SrTiO₃
-CaTiO₃-Bi₂O₃-TiO₂And so on.

Since the fine powders of these sintered bodies are heat-treated at a high temperature of 1000 ° C. or higher, they are chemically stable and do not chemically react with other substances, so that they are liquids for obtaining the elastic body 2. There is no need to select the presence or absence of polarity of the raw material or the polymer forming the elastic body 2 and the temperature of the manufacturing process. Since the particle size of the fine powder can be made as small as possible, it is possible to suppress the positional variation of the electric resistance of the conductive elastic body mixed with the ceramic fine powder 4.

Further, by selecting the ceramic fine powder 4 having a large dielectric constant, the ceramic fine powder 4 can be obtained.
Since no electric charge is charged in the column, the volume resistivity does not change even with an applied voltage.

When titanium oxide alone is used, the dielectric constant is
Since it is around 100, not only obstacles such as hardness increase of the elastic body 2 and exudation to the surface of the conductive elastic body due to increase in the mixing amount into the elastic body 2 but also sufficient reduction of volume resistivity can be achieved. No conductive elastic body with medium resistance can be obtained. Therefore, in order to obtain a conductive elastic body having a medium resistance, it is desirable to use the ceramic fine powder 4 having a dielectric constant of 100 or more, and more preferably 200 or more. As the ceramic fine powder 4 satisfying this condition, there are many ceramic fine powders 4 composed of two or more compounds containing at least titanium oxide.

As additives other than the conductive additive, a vulcanizing agent, a flow accelerator, a foaming agent, an antiaging agent, a reinforcing agent, and a filler may be added as required.

As the above-mentioned vulcanizing agent, for example, sulfur, organic sulfur-containing compounds, organic peroxides and the like can be used.
Examples of the organic sulfur-containing compound include tetramethylthiuram disulfide and the like. Examples of the organic peroxide include benzoyl peroxide. Among these, it is preferable to use sulfur because the balance between the vulcanization rate and the foaming rate is improved when foaming is performed together with vulcanization.

As the vulcanization accelerator, for example, inorganic accelerators such as slaked lime, magnesia (MgO) and litharge (PbO), and organic accelerators described below can be used. Examples of the organic accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfene, and aliphatic primary compounds such as n-butylamine, tert-butylamine and propylamine. Oxidative condensates of amines with 2-mercaptobenzothiazole, dicyclohexylamine, pyrrolidine, piperidine and other aliphatic secondary amines with 2-mercaptobenzothiazole, alicyclic primary amines and 2-mercaptopentazo Sulfenamide vulcanization accelerators such as oxidative condensates with thiazoles, oxidative condensates of morpholin-based compounds and 2-mercaptobenzothiazole, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), Tetraethyl thiuram dimonosulfi (TETD), tetrabutyl thiuram dimonosulfide (TBTD), dipentamethylene thiuram tetrasulfide (DPTT) and other thiuram vulcanization accelerators, dimethyldithiocarbamate zinc (ZnMDC), diethyldithiocarbamate zinc (ZnEDC), A dithiocarbamate vulcanization accelerator such as zinc di-n-butylcarbamate (ZnBDC) can be used. Further, a vulcanization accelerating aid may be blended, and for example, a metal compound such as zinc white or a fatty acid such as stearic acid, oleic acid or cottonseed fatty acid may be used.

Examples of the foaming agent include water and AIB.
N. (azobisisobutyronitrile) system, ADCA (azodicarbonamide) system, DPT (dinitrosopentamethylenetetramine) system, TSH (P-toluenesulphonylhydrazide) system, OBSH (4,4'-oxy An organic foaming agent such as bisbenzenesulfonyl hydrazide) is used. The blending amount of the foaming agent is about 5 to 11 parts by weight based on 100 parts by weight of the rubber component of the composition. This is because if it is less than 5 parts by weight, the foaming is insufficient, and if it is more than 11 parts by weight, the foaming agent inhibits the vulcanization and the vulcanization becomes insufficient. When the composition is a foam, the flexibility is improved. When this is used as the transfer means, a sufficient nip between the photoconductor and the transfer means can be secured, and good image quality can be obtained.

Examples of the antiaging agent include imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N'-di-β-naphthyl-p-phenylenediamine and N-phenyl-N'-. Examples thereof include amines such as isopropyl-p-phenylenediamine, di-tert-butyl-p-cresol, phenols such as styrenated phenol, and the like.

Examples of the filler include silica, clay, talc, calcium carbonate, dibasic phosphite (DL
P), basic magnesium carbonate, powder of alumina and the like. When the filler is blended, the strength of the rubber composition is improved.

Next, the method for producing a conductive elastic body according to the present invention will be described. First, the ceramic fine powder 4 composed of the above-mentioned two or more compounds in combination of one kind or two or more kinds, the above-mentioned foaming agent, and An unvulcanized / unfoamed rubber material in which a vulcanizing agent such as hydrogen polysiloxane or sulfur in the presence of an oxide or a platinum catalyst is uniformly dispersed at a desired ratio is used in a known method such as an open roll or a Banbury mixer. Knead using a rubber kneading device. At this time, if necessary, additives such as a vulcanization accelerator, a softening agent, a plasticizer, a reinforcing agent, an antiaging agent, and an antistatic agent may be appropriately added.

Next, the unvulcanized and unfoamed rubber material is
For example, it is formed by a method such as press molding, extrusion molding, injection molding, and is vulcanized / foamed / cured by heat treatment,
By integrating the unfoamed elastic body and the base body 1, the desired elastic body 2 having a shape along the inner peripheral surface of the mold can be obtained.

The base body 1 can be supported by the base body 1 without increasing the hardness of the elastic body 2, and it becomes possible to prevent the durability life from being shortened due to pressure loss due to time-dependent fatigue. The substrate 1 has a heat resistant temperature of 220 on its outer periphery.
A skin layer formed on the surface of the elastic body 2 is coated with an adhesive at a temperature of ℃ and is ground and ground. As a result, the hardness of the elastic body 2 can be reduced, abrasion with the pressure contact member can be prevented, and cracks in the skin layer due to fatigue can be prevented in advance. From the above process, the base 1
A conductive elastic body composed of only the elastic body 2 can be obtained.

The wear deterioration of the conductive elastic body due to the wear load with the pressure contact member, the composition change of the base rubber, the volume specific resistance change of the conductive elastic body due to the inclusion of impurities, the contamination of the pressure contact member by the conductive elastic body, and the like. Considering prevention of defects, cleaning by improving the releasing property of the toner, and increase in strength of the conductive elastic body, the ceramic fine powder 4 is added to the surface layer of the elastic body 2 obtained by the above process. Do-
Flexible synthetic resin 3 whose resistivity has been adjusted by
It is preferable that the coating layer consisting of is provided by thermal contraction.

The coating method of the coating layer is not limited to heat shrinkage, but the coating layer is expanded and expanded by a vacuum plate, and the elastic body 2 is placed inside the coating layer.
Alternatively, various other techniques can be used. At this time, an adhesive may be used between the elastic body 2 and the coating layer, but the coating layer can be easily peeled off at the time of recycling, and the adhesive may exude to the surface of the conductive elastic body. It is preferable that the elastic body 2 and the coating layer be bonded to each other without using an adhesive agent. That is, by bonding the coating layer without using an adhesive, the coating layer can be easily peeled off at the time of recycling, and the lower layer of the coating layer can be reused as it is, which is environmentally friendly and reduces costs. Also becomes. Further, the adhesive does not exude to the surface of the conductive elastic body, and it is possible to prevent the adverse effect on the volume resistivity of the entire rubber roller.

Next, the foamed elastic body having a roller shape which is an embodiment of the present invention is preferably manufactured by the following method in terms of workability and performance. Ie the desired
Mix the appropriate amount of ceramic fine powder 4 such as BaTiO ₃ or PbTiO ₃ -PbZrO ₃ with the kneading machine for 60 to 120
The mixture is kneaded at 5 ° C. for 5 to 30 minutes, formed into a tube by an extrusion molding machine, and the substrate 1 is inserted into the inner diameter portion. And 12
Vulcanizes at 0 to 200 ° C for 5 to 30 minutes and secondary vulcanization at 150 to 180 ° C for 1
Do ~ 4 hours. At this time, a blowing agent such as azodicarbonamide described above was charged at the same time as the heating, and the average cell diameter was 250
It is possible to obtain a foamed elastic body having a thickness of not more than μm and a hardness within the range of 20 to 60 degrees. After the end of the flow, the electroconductive elastic body taken out is subjected to surface polishing as necessary so as to have a desired diameter, thereby removing the skin layer, and when the roller shape is the outer diameter, Roundness and cylindricity
If the shape is a straight shape, straightness and flatness are obtained.

Next, a flexible synthetic resin 3, for example, a tube made of a polyethylene resin tube is heat-shrink-bonded to the elastic body 2 and then heat-sealed to form a coating layer. The polyethylene resin tube used here is BaTiO ₃ or PbTiO ₃
-PbZrO ₃ or other ceramic fine powder 4 is mixed to adjust the volume resistivity to preferably 10 ⁴ to 10 ¹² Ω · cm, and does not need to have heat shrinkability, but is preferably It is heat-shrinkable. At this time, no adhesive was used.

The flexible synthetic resin tube thus adhered to the elastic body 2 is fused to the foamed rubber elastic layer by heating, and it is desirable that the heating at that time is as uniform as possible, and air circulation is performed. It is preferable to gradually raise the temperature using a heating furnace of the formula. And the temperature range of the heat treatment is 10
It is preferably in the range of 0 to 170 ° C. If the temperature is lower than 100 ° C., the adhesion is not sufficient, and if the temperature is higher than 170 ° C., defects such as surface smoothness and hardness of the elastic layer vary, which is not desirable.

The results of an experiment conducted by incorporating the roller-shaped conductive elastic body according to the present invention into the image forming apparatus shown in FIG. 4 will be described below. The roller length here is 220 mm. (Same as coating length), Roller diameter and elastic layer thickness are 18φ and 5mm roller and 30φ and 8mm roller are used. investigated.

First, Table 1 shows the results of an investigation conducted on the thickness of the flexible synthetic resin as the coating layer, which is 10 to 300 μm. If the thickness of the flexible synthetic resin is 30 μm or less, especially 10
In the vicinity of μm, not only wrinkles occurred during molding, but it was not possible to have sufficient wear resistance, and pinholes were generated due to charging, abnormal discharge during transfer, etc.
In the case of 270 μm or more, the hardness of the conductive elastic body was increased, and it was not possible to obtain a conductive elastic body having a desired hardness.

Next, Table 2 shows the results of an investigation conducted on the elongation percentage of the flexible synthetic resin as the coating layer, 0 to 600%.
When the elongation rate is 10% or less, especially near 0%, cracking of the coating layer occurs during pressure contact with the facing member, and when it is 500% or more, especially when it is 600% or more, the polishing property deteriorates, which is desirable. No surface roughness (cylindricity / flatness) was obtained.

[0069]

[Table 1]

[0070]

[Table 2] Next, Table 3 shows the results obtained by investigating the electrical characteristics of the conductive elastic body with respect to the average particle size and the dielectric constant of the ceramic fine powder.
And 4 are shown. When the average particle size is 6 μm or less, the ratio of the part with the highest resistance value and the part with the lowest resistance value of 5 μm or less is less than 1.2 times, and when the dielectric constant is 200 or less, especially 100 or less. It was found that the volume resistivity depends on the applied voltage, and the volume resistivity increases rapidly with the increase of the applied voltage. This tendency almost disappears when the dielectric constant exceeds 300. Therefore, when used for charging, development and transfer means, the average particle size of the ceramic fine powder is 6 μm.
Or less and a dielectric constant of 100 or more, more preferably an average particle size of 5 μm
The following and above 300 have been found to be desirable.

[0071]

[Table 3]

[0072]

[Table 4] Next, Table 5 shows the results of an investigation conducted on the overall hardness of the conductive elastic body of 5 to 80 °. If the hardness is less than 10 °, especially in the vicinity of 5 °, it may not have sufficient restoring force and C-set
When the angle is 70 ° or more, and particularly 80 ° or more, the opposing member such as the photoconductor deteriorates due to wear. When it was used as a transfer means, it was possible to obtain a sufficient nip width in the range of 10 to 70 °, more preferably 20 to 60 °.

[0073]

[Table 5] Table 6 shows the results of the investigation on the volume resistivity of the conductive elastic body. As a method for measuring the resistivity, an applied voltage of 1000 V is applied while pressing the conductive elastic member against the photosensitive member with a force of 500 gf on one side, plain paper is passed through, and the transfer current value at this time is measured. . Next, replace the photoconductor with an aluminum tube,
The measured transfer current value is subjected to constant current control for 1 minute, and the voltage value after 1 minute is measured. The volume resistivity was calculated based on the obtained transfer current value and voltage value.

When used as a transfer means, 1 × 10 ⁶ Ω · cm
Below and above 1 × 10 ⁹ Ω ・ cm, especially 1 × 10 ⁵ Ω ・ cm
Below or below 1 × 10 ¹⁰ Ω · cm, the transfer efficiency will decrease due to excess or deficiency of transfer current or Paschen discharge, and toner
A good image could not be obtained due to image deterioration such as scattering and hollow characters. On the other hand, 1 × 10 ⁶ Ω · cm or more 1 × 1
0 ⁹ Ω · cm or less, especially 1 × 10 ⁸ Ω · cm or less and 1 × 1
In the case of 0 ⁷ Ω · cm or more, good image quality could be obtained by controlling only the applied voltage.

[0075]

[Table 6] From the above, the thickness of the flexible synthetic resin forming the coating layer is
With a thickness of 30 μm to 250 μm, it is possible to prevent pinholes due to wrinkles and charging during molding, abnormal discharge during transfer, etc., while maintaining the appropriate hardness, volume specific resistance, and wear resistance of the conductive elastic body. can do.

The set value of the volume resistivity is preferably about 10 ⁷ to 10 ⁸ Ω · cm in consideration of the transfer efficiency, the image quality such as toner scattering due to transfer, and hollow characters. As long as the variation in electrical resistance position and the variation in electrical resistance during continuous energization are within 1.2 times, and the variation in resistivity due to environmental changes and the variation in resistivity with applied voltage are within 0.5 digits, there is no problem in actual use. It could be confirmed.

Based on the above-mentioned examination results, the volume resistivity variation of the conductive elastic body due to the environmental change was examined. Each environment (LL: 5 ℃ ・ 20%, NN: 20 ℃ ・ 50%, HH: 35 ℃ ・ 80%)
The measurement results are shown in FIG. The vertical axis
1.0E + 06, 1.0E + 07, 1.0E + 08, 1.0E + 09, 1.0E + 10 are 1.0 × 10 ⁶ , 1.0 × 10 ⁷ , 1.0 × 10 ⁸ , 1.0 × 10 ⁹ and 1.0 × 1 respectively.
0 ¹⁰ , and the same applies to the notations in FIGS. 6 to 8.

For comparison, a conductive elastic body made of a polar polymer doped with an ion conductive filler and a conductive elastic body made of a non-polar polymer doped with carbon black (ion A conductive elastic body doped with a conductive filler,
The conductive elastic body doped with carbon black and the conductive elastic body according to the embodiment of the present invention were measured and the difference was verified. As a result, the environmental changes from LL to HH,
The total volume of the conductive elastic body made of a polar polymer doped with an ion conductive filler with a resistivity of 2 × 10 ⁸ Ω · cm (NN value) fluctuates by 1.5 digits, while the total volume changes. Resistivity is 9 × 10
The conductive elastic body of the present invention having a resistance of ⁷ Ω · cm (NN value) and the carbon black having a total volume resistivity of 1 × 10 ⁸ · cm (NN value) are added.
The conductive elastic body made of a nonpolar polymer is almost unchanged.

Next, 0.2 to 2.6 is applied to each of the above conductive elastic bodies.
The applied voltage was changed every 0.2 kV up to kV, and the change in volume resistivity was measured from the value of the transfer current flowing at that time. The obtained results are shown in FIG.

Comparing the volume specific resistivities when 600 V (0.6 kV) and 1400 V (1.4 kV) are applied, the polarities obtained by doping the conductive elastic body and the ion conductive filler according to the embodiment of the present invention are shown. There is almost no change in the conductive elastic body made of a polymer, whereas it changes by one digit in the conductive elastic body made of a non-polar polymer doped with carbon black. Was obtained.

That is, the smaller the applied voltage dependency of the resistivity is, the better the transfer can be performed without being influenced by the type and size of the transfer material. Therefore, the conductive elastic body according to the present invention has a good transfer property. Will have.

Next, FIG. 7 shows the result of examining the positional variation of the electric resistance. The condition at this time is the outer diameter φ1
8.Using a conductive elastic body with a length of 245 mm, 10 mm wide copper tape is equidistantly installed at 4 points every 90 degrees in the circumferential direction and 8 points in the longitudinal direction, for a total of 32 points, measured at an applied voltage of 1000 V Is to do.

As a result, in the conductive elastic body and the conductive elastic body composed of the polar polymer doped with the ion conductive filler in the present embodiment, the portion having the highest resistance value has the lowest resistance value. While it was 1.2 times the part,
It was about 6.6 times in the case of a conductive elastic body composed of a non-polar polymer doped with carbon black.

The conductive elastic body of the present embodiment and a conductive elastic body made of a polar polymer doped with an ion conductive filler, and a conductive elastic body made of a non-polar polymer doped with carbon black. An actual machine test was conducted to confirm the performance when actually forming an image using an elastic body.

Here, the photosensitive member of the image forming apparatus was changed to an aluminum tube, and after continuously rotating for 150 hours while applying a voltage of 1000 V under NN, the volume resistivity was measured by the same method as described above. Was measured. as a result,
In the comparison before and after continuous energization, the resistivity increase in the conductive elastic body of the present invention and the conductive elastic body made of a non-polar polymer doped with carbon black was within 1.2 times, The increase in resistivity was more than 7 times in the conductive elastic body made of polar polymer doped with conductive filler.

Then, the conductive elastic body recycled by peeling off the coating layer of the deteriorated conductive elastic body of the present invention and providing the coating layer again on the same elastic layer has the same performance as the novel conductive elastic body. It was confirmed that can be reproduced. As a result, it becomes possible to facilitate the recycling of such a polymer foam elastic body, and it is also environmentally friendly to reduce the manufacturing cost. Further, cleaning was difficult because the toner was clogged on the surface of the conductive elastic body without the coating layer, but the conductive elastic body provided with the coating layer had a good releasability of the toner and had a good cleaning property. -The training was easy.

FIG. 8 is a graph showing transfer efficiency, missing characters, and toner scattering by the conductive elastic body according to the present embodiment. FIG. 8A shows a case where the conductive elastic body has a coating layer, and FIG.
Represents the case without a coating layer. And LL, NN,
When a grayscale, black solid, and white solid image was printed in an HH environment, the conductive elastic body provided with the coating layer as shown in FIG. While the toner scattering and the uneven density are not generated), the conductive elastic body without the coating layer has a lower transfer efficiency in the LL and a desired density as shown in FIG. 8B. Was not obtained.

Regarding the conductive elastic body provided with the coating layer,
Since the volume resistivity of the coating layer is set higher than that of the elastic layer (ρ1> ρ2), the transfer current does not escape even if the size of the recording paper becomes smaller than the width of the conductive elastic body. I was able to obtain image quality. The experimental results at that time are shown in Table 7.

[0089]

[Table 7]

[0090]

According to the present invention, by using ceramic fine powder as the conductive filler for the elastic body, it is more chemically stable than the ion conductive filler such as quaternary ammonium salt, and the elastic body. There is an effect that it does not cause a chemical change with the polymer or other mixed substances constituting the polymer, and the polarity of the polymer constituting the elastic body or the heating temperature in the manufacturing process is not selected.

Further, since it is possible to make the particle size smaller than that of the electronic conductive filler such as carbon black, the position variation of the electric resistance due to the distribution state of the conductive filler and the variation of the volume resistivity due to the applied voltage. Does not occur. Therefore, ideal conductivity that suppresses problems such as environmental changes of ionic conductive fillers and electronic conductive fillers, volume resistivity fluctuations due to applied voltage, electric resistance position variations, and electric resistance fluctuations during continuous energization. A flexible elastic body can be obtained.
If there is no change in resistivity with environmental changes, it is not necessary to detect each environmental condition and change the transfer bias according to the detected environment.

Further, the dielectric constant of the above ceramic fine powder is
When it is 300 or more, when a voltage is applied to the conductive elastic body, the electric current gradually increases as the applied voltage rises without charging the ceramic fine powder with electric charge. The fluctuation of the rate can be suppressed,
It is also possible to prevent fluctuations in electric resistance during continuous energization.

Further, since the sintered fine powder made of at least two kinds of compounds is used as the ceramic fine powder, it is more chemically stable than the sintered fine powder made of one compound. , Without causing chemical change with the polymer or other mixed substances that make up the elastic body,
The presence or absence of polarity of the polymer constituting the elastic body and the heating temperature in the manufacturing process are not selected. In addition, the price can be relatively low, which is a special effect.

Furthermore, by including titanium oxide in at least one compound of the sintered fine powders of the above-mentioned two or more compounds, it is possible to obtain sintered fine powders having a dielectric constant of 150 or more and at low cost. It becomes easy to manufacture, and it is possible to provide an environment-friendly conductive filler.

[0095]

Further, as the ceramic fine powder, a sintered fine powder made of at least three kinds of compounds is used, so that it is more chemical than the sintered fine powder made of one or two kinds of compounds. It is stable, does not cause unnecessary chemical changes with the polymer or other mixed substances forming the elastic body, and does not select the presence or absence of polarity of the polymer forming the elastic body or the heating temperature in the manufacturing process. Also 1, 2
There is also an effect that it is possible to obtain a sintered compact fine powder having a dielectric constant higher than that of the sintered compact fine powders made of various compounds.

Furthermore, when at least titanium oxide is contained in one compound of the sintered fine powder composed of three or more compounds, it becomes easy to obtain a sintered fine powder having a dielectric constant of 300 or more. It is possible to provide a conductive filler that can be manufactured at low cost and that is environmentally friendly.

[0098] Furthermore, the sintered body powder consisting of the three or more compounds _{PbTiO 3 -PbZrO 3, BaTiO 3 -SrTiO} 3 -La 2 O 3
-TiO ₃ makes it possible to provide a conductive filler having a dielectric constant of 600 or more, and the current gradually increases as the applied voltage rises. Can be suppressed.

Furthermore, since the average particle size of the ceramic fine powder is 5 μm or less, it is possible to realize a dispersed state equivalent to the case where an ion conductive filler is used, so that the electric resistance varies in position. It is possible to obtain a non-conductive elastic body.

[0100]

[0101]

The volume resistivity of the conductive elastic body is
When it is set to 10 ⁶ to 10 ⁹ Ω · cm, when it is used as a transfer means, it is possible to obtain a good transfer performance in all environments regardless of the transfer material.

Furthermore, by providing a coating layer on the surface layer of the conductive elastic body, the conductive elastic body is worn and deteriorated due to the abrasion load with the pressure contact member, the composition of the base rubber is changed, and the conductive elastic body is mixed with impurities. It is possible to prevent problems such as a change in volume specific resistivity, contamination of the pressure contact member due to the conductive elastic body, and by adding conductivity to the coating layer with ceramic fine powder, environmental changes, volume resistivity due to applied voltage It is possible to suppress fluctuations and position variations in electric resistance. If there is no change in the resistivity due to the environmental change, it is possible to obtain a special effect that the control of detecting each environmental condition and changing the transfer bias according to the detected environment becomes unnecessary.

[0104] Incidentally, may be configured so that the coating layer is made of a flexible synthetic resin, the composition of the wear deterioration and base rubber of the conductive elastic body due to abrasion load of the pressing member in the case of this Changes in volume resistivity of the conductive elastic body due to changes and mixing of impurities, further prevent problems such as contamination of the pressure contact member by the conductive elastic body, further facilitate cleaning by improving the toner releasability, A long life can be realized by increasing the strength of the conductive elastic body. Further, since the flexible synthetic resin can be easily peeled off, the lower layer of the coating layer can be reused as it is, which is environmentally friendly and reduces the cost.

Further, the thickness of the flexible synthetic resin forming the coating layer may be 30 μm to 250 μm. In this case, wrinkles and charging during molding and abnormalities during transfer may occur. In addition to preventing pinholes due to electric discharge,
It is also possible to maintain appropriate hardness, volume specific resistance, and wear resistance of the conductive elastic body.

[0106]

[0107]

Furthermore, the substrate of the flexible synthetic resin forming the above-mentioned coating layer may be a non-polar polymer resin, so that a conductive elastic body which does not cause a change in volume resistivity due to environmental changes. can get. Further, the flexible synthetic resin can be easily peeled off, and the lower layer of the coating layer can be reused as it is, which is environmentally friendly and reduces the cost.

Furthermore, by using polyethylene as the substrate of the flexible synthetic resin forming the coating layer, the coating layer itself does not change in volume resistivity due to environmental changes. It is possible to suppress a change in volume resistivity due to a change in the body environment. In this case, the toner has excellent ozone resistance, not only increases the strength of the conductive elastic body, but also improves the mold release property of the toner and improves the cleaning property, and the toner is not easily transferred to the cell on the surface of the conductive elastic body. It is possible to prevent an increase in the volume resistivity of the conductive elastic body by preventing the intrusion of the. Further, since the flexible synthetic resin can be easily peeled off, the lower layer of the coating layer can be reused as it is, which is environmentally friendly and reduces the cost.

Further, as a means for adhering the coating layer to the surface layer of the conductive elastic body, the coating layer may be adhered without using an adhesive, and the coating layer is easily peeled off at the time of recycling. Since it is possible to reuse the lower layer of the coating layer as it is, it is environmentally friendly and reduces the cost. Also, the adhesive does not exude to the surface of the conductive elastic body,
The adverse effect on the volume resistivity of the rubber roller as a whole can be prevented.
It

Furthermore, the conductive elastic body may be in the shape of an endless belt. In this case,
For example, when it is used as a transfer belt, high image quality can be realized due to the advantage that a large nip width can be obtained, and in the case of color, it can be used for a tandem system having a faster process speed than the multiple transfer system. Further, since the transfer material is conveyed together with the transfer belt, the transfer material can be properly conveyed.

Further, it may be so arranged that at least one layer of the above-mentioned conductive elastic body is provided on the base body. In this case, the conductive elastic body is made into the base body without increasing the hardness of the conductive elastic body. When used in a machine, it is possible to prevent pressure loss due to time-related fatigue and shorten the durability life, which facilitates design and mass production.

Furthermore, the conductive elastic body may be formed into an endless roller shape. In this case, when it is used as a transfer roller, for example, it is possible to facilitate the pressure contact with the opposing member (OPC) and transfer it. Therefore, a sufficient nip width can be obtained and a high quality image can be obtained. Further, since the opposing member (OPC) and the transfer roller press-contact the transfer material, it is possible to realize proper transfer of the transfer material.

[0114]

Furthermore, by using the conductive elastic body as a charging, developing and transferring means, the volume resistivity of the conductive elastic body does not change due to environmental changes, so an expensive power source for changing the applied voltage or the like can be used. It is not necessary and leads to cost reduction of the machine. Furthermore, it is excellent in ozone resistance and not only increases the strength of the conductive elastic body, but also improves the releasing property of the toner and improves the cleaning property, so that the toner of the toner on the surface of the conductive elastic body can be improved. By preventing the intrusion, it is possible to prevent the volume resistivity of the conductive elastic body from rising, and an image with excellent quality can be obtained. Further, since the flexible synthetic resin can be easily peeled off, the lower layer of the coating layer can be reused as it is, which is environmentally friendly and leads to cost reduction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a conductive elastic body having a roller shape according to an embodiment of the present invention.

FIG. 2 is a perspective view of a conductive elastic body having a roller shape according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a schematic configuration of a conductive elastic body having a blade shape according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a schematic configuration when a roller-shaped conductive elastic body according to an embodiment of the present invention is applied to an image forming apparatus.

FIG. 5 is a graph showing a change in specific volume resistivity of the conductive elastic body according to an embodiment of the present invention in each environment.

FIG. 6 is a graph showing changes in the volume resistivity of the conductive elastic body according to an embodiment of the present invention when the applied voltage changes.

FIG. 7 is a graph showing a positional variation of electric resistance of the conductive elastic body according to the embodiment of the present invention.

FIG. 8 is a graph showing transfer efficiency, character missing, and toner scattering by the conductive elastic body according to the embodiment of the present invention.
(A) shows the case where the conductive elastic body has a coating layer, and (b) shows the case where it does not have a coating layer.

[Explanation of symbols]

1 base 2 elastic body 3 surface layer 4 Ceramic fine powder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01B 3/12 303 H01B 3/12 303 326 326 326 3/44 3/44 F (72) Inventor Hideki Onishi Mayor Abeno, Osaka City 22-22 Ikemachi Sharp Corporation (72) Inventor Shiro Wakahara 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture (56) References JP-A 2001-72806 (JP, A) JP-A-11 -160960 (JP, A) JP-A-7-271176 (JP, A) JP-A-6-159349 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 5/02 H01B 3/12 H01B 3/44 G03G 15/02 101 G03G 15/08 501 G03G 15/16

Claims (3)

(57) [Claims] 1. A at least three-layer structure comprising a base portion made of a core body, an elastic portion made of an elastic body having conductivity and covering the base portion, and a surface layer portion having conductivity and covering the elastic portion. The conductive filler that is mixed to add conductivity to the elastic portion is a ceramic having an average particle diameter of 5 μm or less and a dielectric constant of 300 or more.
A mixed fine powder , further, as the ceramic fine powder, a sintered fine powder composed of two or more compounds is used, and one compound of the sintered fine powder contains titanium oxide, The surface part is a conductive elastic body characterized in that a non-polar flexible synthetic resin tube is coated on the surface of the conductive part by a contracting action. 2. The thickness of the surface portion is 30 μm to 250 μm.
The conductive elastic body according to claim 1, wherein the conductive elastic body has a thickness of μm. 3. A process according to claim 1 to the conductive elastic body according to any one of claims 2, charging means for contact-charging the surface of an image bearing member, an electrostatic latent image formed on the image bearing member surface An image forming apparatus, which is used as at least one of a developing unit that supplies a developer to a developing unit to visualize the image, and a transfer unit that transfers the visible image formed on the image carrier to a recording medium. apparatus.