JPH0333768A - Electrifying member - Google Patents

Abstract

PURPOSE:To provide a uniform electrifying character without an electrification unevenness and to obtain a satisfactory picture quality without image defects by providing an elastic layer, a conductive layer and a resistance layer from a conductive substrate surface toward an upper side and, simultaneously, making the resistance layer into the laminated structure of an internal resistance layer and a surface resistance layer. CONSTITUTION:The constitution is executed in a function separate type structure in the order of an elastic layer 3, a conductive layer 4 and the resistance layer on a conductive substrate 2, and simultaneously, the resistance layer is made into the two-layer constitution of an internal resistance layer 5a and a surface resistance layer 5b. Consequently, a contact area and a nip width to a photosensitive substance are widened. Thus, the resistant layer can be brought into contact with the conductive layer uniformly. Thus, since the uniform electrification without the electrification unevenness can be executed, the image defects such as a white spot in a positive development system and a black spot in an inversion development system can be eliminated, and the satisfactory image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charging member, and particularly to a charging member that charges a charged object placed in contact with the charging member.

[Conventional technology]

In electrophotographic methods, for example selenium, cadmium sulfide, zinc oxide, amorphous silicon.

Electrophotographic photoreceptors that use organic photoconductors as photosensitive layers,
Images are obtained by performing basic processes such as charging, exposure, development, transfer, fixing, and cleaning. At this time, the charging process is usually done at a high voltage (
DC 5 to 8 KV) is applied, and charging is performed by the generated corona. However, with this method, a large amount of corona products such as ozone and NOx generated during corona charging alters the surface of the photoreceptor, causing image blurring and deterioration, and dirt on the wire affects image quality, resulting in white spots and white spots in the image. There were problems such as black streaks.

Furthermore, in terms of power, the current flowing toward the photoreceptor is 5 to 3
Most of it flowed to the shield plate, making it inefficient as a charging means.

In order to compensate for such problems, Japanese Patent Laid-Open Nos. 57-178267 and 1982-178 do not use a corona discharger.
No. 104351, Japanese Patent Application Laid-open No. 58-40566,
JP-A-58-139156, JP-A-58-150
As proposed in Japanese Patent No. 975, etc., contact charging methods are being researched.

Specifically, by contacting a charging member such as a conductive elastic roller to which a DC voltage of about 1 to 2 KV is externally applied to the surface of the photoreceptor, charges are directly injected into the surface of the photoreceptor, and the surface of the photoreceptor is adjusted to a predetermined position. It is charged to a potential of .

In such charging members such as conductive elastic rollers, conductive rubber in which conductive particles such as carbon are dispersed is fixed to a metal core material, and as the amount of carbon dispersed in the conductive rubber increases and becomes denser, Rubber hardness increases. Therefore, the rubber hardness changes due to unevenness or variation in the degree of carbon dispersion, and local variations in hardness on the roller surface tend to occur, which hinders the degree of adhesion to the photoreceptor surface.

Furthermore, even when increasing the nip width by setting the rubber hardness of the electrode roller to, for example, 40' or less to improve adhesion to the photoreceptor surface, the electrode roller has a single layer structure in which only conductive rubber is used as the metal core. In order to reduce the hardness, the amount of carbon dispersed is made coarser, which tends to cause variations in conductivity on the roller surface and variations in roller hardness.

Such surface non-uniformity makes it impossible to uniformly charge the photoreceptor, causing uneven charging.

Furthermore, as in Japanese Utility Model Application Publication No. 57-199349, by making the electrode roller have a two-layer structure of an elastic rubber layer and a semiconductive rubber layer, the hardness of the roller can be adjusted by the elastic rubber layer and the nip width can be increased. has also been proposed. however,
In this case as well, unevenness on the surface of the electrode roller that is in pressure contact with the photoreceptor surface makes it difficult to obtain a contact surface, which tends to result in uneven charging.

As described above, even if charging is performed by the contact charging method using the above-mentioned charging member, each part of the surface of the photoreceptor is not uniformly charged, resulting in spot-like charging unevenness. In the reversal development method, even if a process below photoimage exposure is applied to a photoconductor with spotty charging unevenness, the output image will be a spotty black dot image (black spots) corresponding to the spotty charging unevenness, and it will not be accurate. In the development method, a speckled white dot image (white dots) is produced in contrast to the speckled unevenness, and a high-quality image cannot be obtained.

In order to solve these problems and eliminate uneven charging,
It has been proposed to superimpose an alternating current voltage on a direct current voltage applied to a charging member.

If only a DC voltage is applied, the charging property will be greatly affected by the surface properties of the charging member, but the DC voltage (V DC
) by superimposing an alternating current voltage (VAC) to apply a pulsating current voltage (V oc + V AC) to perform uniform charging without being affected by the surface properties of the charging member.

In this case, in order to maintain charging uniformity and prevent image defects such as white spots in the normal development method and black spots or blur in the reversal development method, the superimposed AC voltage must have a certain peak-to-peak potential difference (V p- p).

However, when the superimposed alternating current voltage is increased to prevent image defects, the brightest applied voltage of the pulsating current voltage tends to cause discharge dielectric breakdown at a slight defect site during coating inside the photoreceptor. Furthermore, when there is a pinhole, there is a problem in that the pinhole becomes a conductive path, current leaks, and the voltage applied to the charging member drops. In this case, in the normal development system, the image will be blanked out over the longitudinal direction of the contact area, and in the reversal development system, black streaks will occur.

Furthermore, due to the hardness of the charging member, the frequency of the superimposed alternating current voltage causes the charging member to vibrate, and this vibration is transmitted to the photoreceptor that is in close contact with it, causing unpleasant noise to be generated from the photoreceptor. there were.

[Problem that the invention seeks to solve]

The object of the present invention is to have uniform charging ability without charging unevenness,
It is an object of the present invention to provide a charging member that can provide good image quality without image defects.

Another object of the present invention is to provide a charging member that prevents voltage drop due to current leakage even when there is a pinhole, without causing dielectric breakdown at a defective portion of a photoreceptor.

Another object of the present invention is to provide a charging member that prevents unpleasant noises caused by vibrations caused by applied alternating current voltage.

Another object of the present invention is to provide a charging member that does not ooze out onto the surface even when a plasticizer is added to impart flexibility.

That is, the present invention provides a charging device characterized in that it has an elastic layer, a conductive layer, and a resistive layer upward from the surface of a conductive substrate, and the resistive layer has a laminated structure of an internal resistive layer and a surface resistive layer. It is a member for use.

For convenience, the photoreceptor charging process (
(including static elimination processing) will be explained as an example.

As shown in FIG. 1, the charging member 1 of the present invention basically consists of a conductive substrate 2 and an elastic layer 3. Conductive layer 4 and resistive layer 5
It is configured in a functionally separated structure in the order of
has a two-layer structure of an internal resistance layer 5a and a surface resistance layer 5b.

In addition, when charging a photoreceptor using this charging member, as shown in FIG. 2, by applying a voltage from an external power source 6 connected to the charging member 1, The photoreceptor placed in contact with the photoreceptor 1 is charged.

When the charging member has the configuration of the present invention, the contact area and nip width with respect to the photoreceptor are expanded, and uniform contact can be achieved. Therefore, uniform charging without charging unevenness can be performed, thereby eliminating image defects such as white spots in the normal development method and black spots in the reversal development method, thereby making it possible to obtain a good image.

That is, the resistance layer is made of nylon or cellulose.

Since it can be formed from a thin resin layer such as polyester or polyethylene, its surface is uniform, smooth, and has less uneven thickness. Furthermore, by separately providing an elastic layer and a conductive layer inside the charging member, flexibility and conductivity can be controlled separately, solving the problem of conventional conductive rubber that is difficult to soften. The charging member of the present invention having such a structure maintains sufficient conductivity by the conductive layer, and also obtains uniform adhesion to the photoconductor by the flexibility of the elastic layer and the surface smoothness of the resistive layer. Therefore, uniform charging without uneven charging can be performed.

Furthermore, in the present invention, by separately providing a conductive layer and a resistive layer, it is possible to prevent dielectric breakdown caused by internal defects in the photoreceptor, and even if there is a pinhole, in the case of a positive development method, it is possible to prevent dielectric breakdown caused by internal defects in the photoreceptor. In the white blanking and reversal development methods, image defects such as black streaks can be prevented and excellent images can be obtained.

That is, usually dust when coating the photoreceptor.

Paint film defects such as dents are an unavoidable problem, but if the conductive layer of the charging member is in direct contact with this photoreceptor, the defect will be locally affected due to the low resistance of the defective part. Electric charge is concentrated and dielectric breakdown is more likely to occur. Furthermore, if there is a pinhole on the photoreceptor, a conductive path is formed inside the photoreceptor that is in contact with the conductive layer, causing leakage and the escape of charges. For this reason, a load is applied to the external power supply unit for applying the voltage, and a phenomenon occurs in which the voltage applied to the photoreceptor drops. In this phenomenon, there is no charge on the contact area between the photoreceptor with the pinhole and the charging member, so
When viewed as an image, in the normal development method it appears as a white mark extending along the length of the contact area, and in the reverse development method it appears as a black streak extending in the longitudinal direction of the contact area.

On the other hand, since the charging member configured according to the present invention has a resistive layer in the contact portion with the photoreceptor, the charges are dispersed and dielectric breakdown at the defective portion can be prevented. Further, even if conduction occurs at the pinhole portion of the photoreceptor, the presence of the resistive layer maintains resistance to the applied voltage, so no load is applied to the external power supply section, and voltage drop can be prevented. Therefore, image defects such as white spots or black lines caused by pinholes can be prevented.

Further, the charging member of the present invention can prevent or reduce noise caused by alternating current waves of alternating current voltage applied and superimposed from an external power source.

That is, the conventional charging member has a drawback in flexibility because it maintains conductivity, and the alternating current wave of the applied voltage causes vibration in the charging member. This vibration is directly transmitted to the photoreceptor placed in contact with the charging member, and unpleasant noise is generated from the photoreceptor and the interior of the photoreceptor. On the other hand, the charging member of the present invention absorbs vibrations caused by the applied pulsating voltage due to the flexibility of the elastic layer between the conductive base and the conductive layer. Therefore, vibrations are not transmitted to the photoreceptor that is in contact with the charging member, so that unpleasant noise from the photoreceptor and the inside of the photoreceptor accompanying the vibration can be prevented or reduced.

Further, in the charging member of the present invention, the resistance layer has a two-layer structure as described above.

In other words, if a material for forming the resistance layer is a resin or rubber with a plasticizer added as a compounding agent to increase flexibility, the added plasticizer may affect the surface of the resistance layer depending on the durability of the charging member and the environment in which it is used. (transfer) may occur. In this case, the photoreceptor placed in contact with the charging member may be adversely affected by the seeped plasticizer, causing the photoconductive material in the photoreceptor to denature, or the photoreceptor may stick to the charging member, causing the photoreceptor to The surface will peel off. In order to prevent such adverse effects, in the present invention, the resistance layer of the charging member is divided into two layers: an internal resistance layer and a surface resistance layer. By this, in order to give flexibility to the internal resistance layer, a flexibility imparting agent such as a plasticizer is added, and a surface resistance layer is provided on top of it to prevent the plasticizer etc. from seeping out to the surface. This results in a charging member that is more flexible. Such a charging member has further improved adhesion with the photoreceptor and is more effective in charging performance and noise prevention.

Hereinafter, the structure of the charging member of the present invention will be explained.

Conductive substrates include metals such as iron, copper, and stainless steel;
Conductive resins such as carbon-dispersed resins and metal particle-dispersed resins can be used, and the shape thereof can be rod-like, plate-like, etc.

The elastic layer is a layer with high elasticity and low hardness, and is JI
Rubber hardness measured with a JIS-A quantity measuring device (Chiklok G5-706: manufactured by Chiklok Co., Ltd.) in accordance with the measurement method of SK-6301 of 35 degrees or less, further 30 degrees or less, especially in the range of 12 degrees to 25 degrees. is preferred. Also, from the above point, the thickness of the elastic layer should be 1.5 mm or more, or even 2 mm.
mm or more, particularly preferably in the range of 3 mm to 13 mm. The elastic layer is formed using rubber or sponge such as chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber, butyl rubber, styrene-butadiene thermoplastic elastomer, polyurethane thermoplastic elastomer, or polyester thermoplastic. elastomer,
Examples include thermoplastic elastomers such as ethylene-vinyl acetate thermoplastic elastomers. Further, if necessary, conductive particles may be added to the elastic layer in order to adjust its hardness.

The conductive layer is a layer with high electrical conductivity and low volumetric efficiency! 0
7Ω・cm or less, further 10'Ω・cm or less, especially 10-
This layer has a conductivity in the range of 2Ω·cmxlo'Ω·cm. In addition, it is desirable that the conductive layer be thin in order to transfer the flexibility of the lower elastic layer to the upper resistive layer.
3 mm or less, further 2 mm or less, especially 20 μm to 1
A range of mm is preferred.

As the material for forming the conductive layer, a metal vapor deposition film, conductive particle dispersed resin, conductive resin, etc. can be used. Specifically, metal vapor deposition films include aluminum, indium,
Examples include those on which metals such as nickel, copper, and iron are vapor-deposited. Carbon, aluminum, and nickel are used as conductive particle-dispersed resins.

Conductive particles such as titanium oxide are combined with urethane, polyester,
Examples include those dispersed in resins such as vinyl acetate-vinyl chloride copolymer and polymethyl methacrylate. Examples of the conductive resin include quaternary ammonium salt-containing polymethyl methacrylate, polyvinylaniline, polyvinylpyrrole, and polydiacetylene.

Examples include polyethyleneimine. Among these, conductive particle-dispersed resins are preferred from the viewpoint of controlling conductivity.

The internal resistance layer is formed to have a higher resistance than the underlying conductive layer, and is 10-10 higher than the volume resistivity of the conductive layer.
It is preferable that the resistance is increased by a factor of 10, particularly by a factor of 102 to 10. The volume resistivity of the internal resistance layer is 10
'Ω・cmwlo''Ω・cm range, especially 107Ω・
The range is preferably from cm to LollΩ·cm. The thickness of the internal resistance layer is 1 μm to 450 μm, particularly 50 μm.
A range of ~200 μm is preferred.

Materials for forming the internal resistance layer include ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, and copolymerized nylon.

Semi-conductive resins such as resins such as polyvinylpyrrolidone and casein, mixtures of these resins, or those in which small amounts of conductive particles are dispersed in these resins, carbon,
Conductive materials such as those in which resistance is adjusted by dispersing a small amount of conductive particles such as aluminum, indium oxide, and titanium oxide in an insulating resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethacrylate ester. Particle-dispersed insulating resins, rubbers such as epichlorohydrin rubber, epichlorohydrin-cotylene oxide rubber, polyurethane rubber, Epoquin rubber, butyl rubber, chloroprene rubber, styrene-butadiene rubber, mixtures of these rubbers, or conductive particles dispersed in these rubbers. Examples include semiconductive rubber such as those containing such a material. Among these, semiconductive rubbers such as epichlorohydrin rubber and epichlorohydrin-ethylene oxide rubber are preferred.

Examples of the plasticizer include phthalic acid compounds such as dibutyl phthalate, phosphoric acid compounds such as tricresyl phosphate, and epoxy compounds such as alkyl epoxy stearate.

When the internal resistance layer is made of resin, the tensile elastic modulus of the resin is 200Kgf/mrd or less from the viewpoint of flexibility, particularly 50Kgf/mrrr to 150K.
A range of g f /m rrr is preferred. Further, when it is made of rubber, the above-mentioned rubber hardness is preferably 35 degrees or less, particularly in the range of 10 degrees to 30 degrees.

The surface resistance layer is formed to have a higher resistance than the conductive layer, as in the case of the internal resistance layer, and is 10 to 10' times higher than the volume resistivity of the conductive layer, particularly 10" to 10". It is preferable that the resistance is higher in the range of twice as high. Further, the resistance of the surface resistance layer may be lower, higher, or the same as that of the internal resistance layer. From the viewpoint of uniformity of charging, it is preferable that the resistance of the internal resistance layer is 1 to 50 times, particularly 2 to 10 times higher than that of the surface resistance layer. The volumetric efficiency of the surface resistance layer is preferably in the range of 10 6 Ω·cm −1 O 12 Ω◆cm, particularly in the range of 10 7 Ω′cm to 10 11 Ω·cm.

Furthermore, the thickness of the surface resistance layer is preferably thinner than that of the internal resistance layer so as not to damage the flexibility of the underlying internal resistance layer, and is preferably 0.1 μm to 50 μm1, particularly 1/1 μm.
1 m to 30 μm is preferable.

Examples of the material for forming the surface resistance layer include resins such as the above-mentioned semiconductive resins and conductive particle dispersed insulating resins.

In addition to these layers, the charging member of the present invention may include other layers such as an adhesive layer that improves the adhesiveness of each layer.

The charging member according to the present invention is manufactured, for example, as follows.

First, a metal rod is prepared as a conductive base of a charging member. The material for the elastic layer is formed on the metal rod by melt molding, injection molding, dip coating, spray coating, etc. to provide the elastic layer.

Next, the conductive layer material is melt-molded, injection molded, and
A conductive layer is provided by molding by dip coating or spray coating.

Finally, the resistive layer material is dip coated onto the conductive layer.

Apply a resistive layer by spray coating, gravure coating, etc.

The shape of the charging member may be any shape such as a roller, a blade, or a belt, and can be selected according to the specifications and form of the electrophotographic apparatus.

In addition, the charging member is used for primary charging, transfer charging,
It can be used for various purposes such as static electricity removal and charging.

There are various types of objects to be charged that can be used in the present invention, such as dielectric materials and electrophotographic photoreceptors, but an electrophotographic photoreceptor is constructed as shown in FIG.

The electrophotographic photoreceptor 7 has a photosensitive layer 9 provided on a conductive support 8 . As the conductive support 8, the support itself is conductive, for example, aluminum.

Aluminum alloy, stainless steel, etc. can be used, and in addition, the conductive support having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide-tin oxide alloy, etc., plastic, conductive particles (for example, carbon black, tin oxide particles, etc.)
A support obtained by impregnating plastic or paper with a suitable binder, a plastic having a conductive binder, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive support 8 and the photosensitive layer 9.

The subbing layer is casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer polyamide,
It can be formed from polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is suitably 5 μm or less, preferably 0.5 μm to 3 μm. In order for the undercoat layer to perform its functions, it is desirable that the volume resistivity value is 10'Ω·cm or more.

The photosensitive layer is formed, for example, by coating a photoconductor such as an organic photoconductor, amorphous silicon, selenium, etc. together with a binder if necessary, or by vacuum deposition. In addition, when an organic photoconductor is used, the photosensitive layer 9 is a charge generation layer l having the ability to generate charge carriers as shown in FIG.
A photosensitive layer having a laminated structure of O and a charge transport layer 11 having the ability to transport generated charge carriers can also be effectively used.

The charge generation layer includes an azo pigment, a quinone pigment, a quinocyanine pigment, a perylene pigment, an indigo pigment, a bisbenzimidazole pigment, and a phthalocyanine pigment.

It can be formed by vapor depositing one or more charge generating materials such as quinacridine pigments, or by dispersing and coating with a suitable binder (or without a binder).

The binder can be selected from a wide range of insulating resins or organic photoconductive polymers. For example, insulating resins include polyvinyl butyral, polyarylate (bisphenol A
and phthalic acid condensation polymers, etc.).

Examples include polycarbonate, polyester, phenoxy resin, acrylic resin, polyacrylamide resin, polyamide, cellulose resin, urethane resin, epoxy resin, casein, and polyvinyl alcohol.

Further, examples of the organic photoconductive external polymer include polyvinylcarbazole, polyvinylanthracene, polyvinylpyrene, and the like.

The thickness of the charge generation layer is 0.01 μm -]55 μm1 or 0.05 μm to 5 μm, and the weight ratio of the charge generation material to the binder is 1 oll to l:20.

The solvent used in the paint for the charge generation layer is selected based on the solubility and dispersion stability of the resin and charge transport material used, and examples of organic solvents include alcohols, sulfoxides, ethers, esters, and aliphatic halogenated solvents. Hydrocarbons or aromatic compounds can be used.

Coating can be performed using a coating method such as a dip coating method, a spray coating method, a Meyer bar coating method, or a blade coating method.

The charge transport layer is formed by dissolving a charge transport material in a film-forming resin. Examples of organic charge transport materials used in the present invention include hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds,
Thiazole compound.

Examples include triarylmethane compounds. These charge transport materials can be used alone or in combination of two or more.

Examples of binders used in the charge transport layer include phenoxy resin, polyacrylamide, polyvinyl butyral, polyarylate, polysulfone, polyamide, acrylic resin, and acrylonitrile resin.

Methacrylic resins, vinyl chloride resins, vinyl acetate resins, phenolic resins, epoxy resins, polyesters, alkyd resins, polycarbonates, polyurethanes, or copolymers containing two or more repeating units of these resins, such as styrene-butadiene copolymers, styrene -acrylonitrile copolymer, styrene-maleic acid copolymer, etc. It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

The thickness of the charge transport layer is 5 to 50 μm, preferably 8 to 20 μm.
μm, and the weight ratio of charge transport material and binder is 5:1
-1:5, preferably about 3:1 to 1:3.

The coating method described above can be used for coating.

Furthermore, since dyes, pigments, organic charge transport substances, etc. are generally susceptible to stains caused by oil, ultraviolet rays, ozone, etc., a protective layer may be provided as necessary. In order to form an electrostatic latent image on this protective layer, it is desirable that the surface efficiency is 10 11 Ω or more.

Protective layers that can be used in the present invention are polyvinyl butyral, polyester, and polycarbonate.

A solution prepared by dissolving resins such as acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-acrylic acid copolymer, and styrene-acrylonitrile copolymer in a suitable organic solvent is applied onto the photosensitive layer. Can be formed by drying.

At this time, the thickness of the protective layer is generally 0.05 μm to 20 μm.
m is preferably in the range of 1 μm to 5 μm. This protective layer may contain an ultraviolet absorber or the like.

The charging member of the present invention can be applied to an electrophotographic apparatus as shown in FIG. This device includes a primary charging roller l, which is a charging member, on the circumferential surface of an electrophotographic photoreceptor 7;
Image exposure means 12. Developing means 13. Transfer charging means 14.
Cleaning means 15. A pre-exposure means 16 is arranged.

A voltage is applied from the outside to the primary charging roller l placed in contact with the electrophotographic photoreceptor 7, the surface of the electrophotographic photoreceptor 7 is charged, and the image on the document is exposed onto the photoreceptor by the image exposure means 12. and forms an electrostatic latent image. Next, the developing means 13
The electrostatic latent image on the photoreceptor is developed (visualized) by adhering the developer therein to the photoreceptor, and the developer on the photoreceptor is then transferred to a transfer member 17 such as paper by the charging means 14.
The cleaning means 15 collects the developer remaining on the photoreceptor without being transferred to the paper during the transfer.

Although an image can be formed by such an electrophotographic process, if residual charges remain on the photoreceptor, the photoreceptor is exposed to light by the pre-exposure means 16 to remove the residual charges before performing primary charging. It is better to eliminate static electricity.

The light source of the image exposure means 12 is halogen light or fluorescent light.

Laser light, LED, etc. can be used.

Examples of the developing means include devices used in two-component development, l-component development using magnetic toner or non-magnetic toner, and the like. Further, the development method may be a normal development method or a reversal development method.

The method of installing the charging member in contact with the photoreceptor in the present invention is not limited to a specific method, and the charging member may be fixed or moved, such as by rotating in the same direction or opposite direction to the photoreceptor. Furthermore, it is also possible to cause the charging member to function as a toner cleaning device on the photoreceptor. In the direct charging method of the present invention, the voltage applied to the charging member is in the form of a pulsating voltage that is a superimposition of a DC voltage and an AC voltage. At this time, this applied voltage is ±200V to ±15V.
It is preferable to use a pulsating voltage obtained by superimposing a DC voltage of 00V and an AC voltage with a peak-to-peak voltage of 2000V or less.

The voltage application method depends on the specifications of each electrophotographic device, but in addition to the method of instantaneously applying the desired voltage, there are also methods of increasing the applied voltage in stages to protect the photoreceptor, and direct current methods. If the voltage is applied in the form of superimposed alternating current, a method can be adopted in which the voltage is applied in the order of direct current → alternating current or alternating current → direct current.

Further, the charging member of the present invention can also be applied with a low DC voltage.

Further, in the present invention, processes such as image exposure, development, and cleaning can be performed using any methods known in the field of electrophotography, and are not limited to specific methods such as the type of developer. An electrophotographic device using the charging member of the present invention can be used not only in copying machines but also in electrophotographic application fields such as laser printers, CRT printers, and electrophotographic plate making systems.

By applying the charging member of the present invention to an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor, which is susceptible to deterioration in terms of mechanical strength and chemical stability, its characteristics can be significantly improved. able to demonstrate.

Example 1 A charging member was manufactured as follows. However, parts indicate parts by weight.

First, centering on an iron core with a diameter of 5 mm and a length of 250 mm,
JI based on JISK-6301 for chloroprene rubber
Rubber hardness measured by S-A type side measuring device is 15'
(Rubber hardness meter manufactured by TECLOCK [TECLOCK G5-7
06]), φ30mm.

Melt molded to a length of 230 mm and a film thickness of 12 mm.
．． A 5 mm elastic layer was formed.

Next, a conductive carbon particle-dispersed polyurethane paint (Cintron, manufactured by Shinto Paint Co., Ltd.) was applied by dip coating onto the elastic layer, and after drying, a conductive layer with a thickness of 20 μm was provided.

Next, 10 parts of ethyl cellulose and 1 part of di-2-ethylhexyl phthalate (DOP) were dissolved in 90 parts of methanol, and the solution was dip coated onto this conductive layer, and after drying, the film thickness was 80 μm.
An internal resistance layer was provided. Next, 1 part of conductive carbon (Ketsutsuen Black, manufactured by Lion), 19 parts of ethyl cellulose
part, surfactant (sorbitol.

Ajinomoto Co., Ltd.) 0.01 part was mixed with 80 parts of methanol,
A surface resistance layer coating solution was prepared by dispersing in a ball mill. This coating liquid was spray-coated on the internal resistance layer, and after drying, a surface resistance layer was provided so that the film thickness was 20 μm, and a primary charging roller 1 was manufactured.

Note that the conductive layer, internal resistance layer, and surface resistance layer are each Af
A separate dip coating was performed on the receipt, and the volume resistivity was measured.

Next, an electrophotographic photoreceptor was manufactured as follows.

First, as a conductive support, 60φX with a wall thickness of 0.5 mm was used.
A 260 mm aluminum cylinder was prepared.

Next, copolymerized nylon (product name: 0M8000.
Co., Ltd.) and Type 8 nylon (trade name Niratsukamite 5003. Dainippon Ink Co., Ltd.) and 4 parts of methanol.
The solution was dissolved in 0 parts and 50 parts of n-butanol and applied by dip coating onto the above conductive support to form a polyamide undercoat layer having a thickness of 0.6 μm.

Next, 10 parts of a disazo pigment having the following structural formula, and polyvinyl butyral resin (trade name: Eslec B
M2. 10 parts of Sekisui Chemical (made by Kiki), 1 part of cyclohexanone
Dispersion was carried out with 20 parts in a sand mill apparatus for 10 hours. 30 parts of methyl ethyl ketone was added to the dispersion and coated on the undercoat layer to form a charge generation layer with a thickness of 0.15 μm.

Next, polycarbonate Z resin with a weight average molecular weight of 20,000 (
(manufactured by Mitsubishi Gas Chemical Co., Ltd.) was prepared and dissolved in 80 parts of monochlorobenzene together with 10 parts of a hydrazone compound having the following structural formula.

This was coated on the charge generation layer to form a charge transport layer with a thickness of 16 μm, thereby producing a photoreceptor Nα1.

A normal development type electrophotographic copying machine (PC-1) was constructed using the photoreceptor Nαl described above, installed a primary charging roller Ha1 in place of the primary corona charger, and was modified to have the configuration as shown in FIG.
0: manufactured by Canon) to apply direct current to the primary charging roller.
50V and AC peak-to-peak voltage of 1300V were applied, dark area potential, bright area potential 2 image defects, leakage and noise measurement when a φ1 mm pinhole was drilled in the photoreceptor (
(Measurements were made at a location one part horizontally away from the copying machine).

These results are shown in Table 1.

Example 2 A core having a diameter of 24 mm and a length of 250 mm was melt-molded with chloroprene rubber to have a diameter of 30 mm and a length of 230 mm to form an elastic layer with a thickness of 3' mm. The rubber hardness of the elastic layer was 15°.

Next, a conductive layer and an internal resistance layer were provided on this conductive layer in the same manner as in Example 1.

Next, 1 part of aluminum powder (Alpaste 54-137° manufactured by Toyo Aluminum), 19 parts of ethyl cellulose, and 0.01 part of surfactant (Solspers, manufactured by ICI) were mixed with 80 parts of methanol, and dispersed in a ball mill to determine the surface resistance. A layered coating solution was created. This coating liquid was spray-coated onto the internal resistance layer, and after drying, a surface resistance layer was provided so that the film thickness was 20 μm, thereby producing a primary charging roller Na 2 .

This primary charging roller was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 3 The conductive layer was formed in the same manner as in Example 1 except that the rubber hardness of the elastic layer in the primary charging roller of Example 1 was changed to 35°.

Next, 19 parts of ethyl cellulose, dibutyl phthalate (D
BP) was dissolved in 90 parts of methanol and applied by dip coating onto the conductive layer. After drying, an internal resistance layer with a thickness of 80 μm was provided.

Next, 1 part of indium oxide powder (manufactured by Dowa Chemical Co., Ltd.) and 19 parts of nitrocellulose were mixed with 70 parts of methanol and dispersed in a ball mill to prepare a surface resistance layer coating solution. This coating liquid was spray coated on the internal resistance layer, and after drying, the film thickness was 20 μm.
A primary charging roller N113 was manufactured by providing a surface resistance layer so as to have a resistance of m.

This primary charging roller was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 In the primary charging roller of Example 1, up to the elastic layer was provided in the same manner as in Example 1, except that EPDM rubber was used instead of chloroprene rubber in the elastic layer. The rubber hardness of the elastic layer is 25e'
Met.

Next, a conductive carbon particle-dispersed polyurethane paint (Cintron, manufactured by Shinto Paint Co., Ltd.) was applied by dip coating onto the elastic layer, and after drying, a conductive layer with a film thickness of 1 mm was provided.

Next, 10 parts of epichlorohydrin rubber (Hydrin, manufactured by Nippon Zeon), 1 part of tricresyl phosphate (TCP),
Zinc oxide 0.3 parts, powdered sulfur 0.2 parts, vulcanization accelerator (
(trimercaptotriazine) and 90 parts of THF were mixed and applied by dip coating onto the conductive layer, resulting in a film thickness of 90 μm after drying.
An internal resistance layer was provided.

Next, 1 part of conductive carbon (Ketsutsuen Black, manufactured by Lion), 19 parts of methoxymethylated nylon, o and oi parts of surfactant (sorbitol, manufactured by Ajinomoto) were added to 8 parts of methanol.
0 parts and dispersed in a ball mill to prepare a surface resistance layer coating solution. Spray this coating liquid onto the internal resistance layer,
After drying, a surface resistance layer was provided so that the film thickness was 10 μm, and a primary charging roller Nα4 was manufactured.

This primary charging roller was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 5 In the primary charging roller of Example 4, the primary charging roller was changed to Nα in the same manner as in Example 4, except that the epichlorohydrin rubber in the internal resistance layer was replaced with epichlorohydrin ethylene oxide rubber (Dekron 2 manufactured by Nippon Zeon).
5 was manufactured.

This primary charging roller was measured in the same manner as in Example 1,
The evaluation results are shown in Table 1.

Example 6 The iron core used in Example 1 was used as an axis, and a urethane thermoplastic elastomer (Miractran 1 Nippon Polyurethane Industries) was used with a rubber hardness of 12°l and a diameter of 31 mm.

It was melt-molded to a length of 230 mm to form an elastic layer with a thickness of 13 mm.

Next, 10 parts of aluminum particles were added to butyral resin (Eslec B
(manufactured by Sekisui Chemical) and 80 parts of methyl ethyl ketone, this coating liquid was dip coated onto the elastic layer, and after drying,
A conductive layer with a thickness of 60 μm was provided.

Next, polyester polyol was added with 10 parts of Tuboran 4032 (manufactured by Nippon Polyurethane Industries), 10 parts of isocyanate (Coroho 1651 manufactured by Nippon Polyurethane Industries), 1 part of di-2-ethylhexyl phthalate (DOP), and 0.3 parts of zinc powder.
0.2 parts of sulfur powder, and 0.1 part of vulcanization accelerator (trimercaptotriazine) were mixed with 80 parts of MEK, and the mixture was dip-coated onto the conductive layer, and after drying, the internal resistance of polyurethane rubber with a film thickness of 95 μm was determined. Layers were provided.

Next, 1 part of conductive carbon (Ketsutsuen Black, manufactured by Lion), nylon 6-66-10 (72970M-8
000, manufactured by Toshi) was mixed with 80 parts of methanol,
A surface resistance layer coating solution was prepared by dispersing in a ball mill. This coating liquid was spray-coated onto the internal resistance layer, and after drying, a surface resistance layer was provided so that the film thickness was 5 μm, thereby producing a primary charging roller Na 6.

This primary charging roller was measured in the same manner as in Example 1,
The evaluation results are shown in Table 1.

Example 7 Styrene-butadiene thermoplastic elastomer (Denka STR) was used around the iron core used in Example 1.

(manufactured by Denki Kagaku Kogyo), rubber hardness is 15°, φ27mm.

Melt and mold to a length of 230mm and a film thickness of 11mm.
An elastic layer was formed.

Next, 10 parts of TiO2 particles were mixed with 10 parts of butyral resin (Eslec BLS, manufactured by Sekisui Chemical) and 80 parts of methyl ethyl ketone.
This paint was applied on the elastic layer by dip coating, and after drying, a conductive layer with a film thickness of 5 mrn was formed.

Next, 10 parts of nitrocellulose and 1 part of di-2-ethylhexyl phthalate (DOP) were dissolved in 90 parts of methanol, and the solution was dip coated onto the conductive layer to form an internal resistance layer having a thickness of 95 μm after drying.

Next, titanium oxide particles (ECT-62: Titanium Kogyo) 0
．． 1 part of nitrocellulose was mixed with 190 parts of methanol and dispersed in a ball mill to prepare a surface resistance layer coating solution. This coating liquid was spray coated onto the internal resistance layer, and after drying, a surface resistance layer having a film thickness of 5 μm was provided to produce a primary charging roller Nα7.

This primary charging roller was measured in the same manner as in Example 1,
The evaluation results are shown in Table 1.

Example 8 A primary charging roller including a conductive layer was prepared in the same manner as in Example 7.

Next, polyester polyol was added with 10 parts of Tuboran 4032 (manufactured by Nippon Polyurethane Industries), 10 parts of isocyanate (Coroho 1652 (manufactured by Nippon Polyurethane Industries)), 1 part of di-2-ethylhexyl phthalate (DOP), and 0 parts of zinc powder.
．． 3 parts of sulfur powder, 0.2 parts of sulfur powder, and 0.1 part of vulcanization accelerator (trimercaptotriazine) were mixed with 80 parts of M E K and dip coated onto the conductive layer to form a polyurethane film with a film thickness of 95 μm after drying. An internal resistance layer made of rubber was provided.

Next, 10 parts of ethyl cellulose was dissolved in 90 parts of methanol to prepare a surface resistance layer coating solution. This coating liquid was spray coated onto the internal resistance layer, and after drying, a surface resistance layer having a film thickness of 10 μm was provided to produce a primary charging roller Nα8.

This primary charging roller was measured in the same manner as in Example 1,
The evaluation results are shown in Table 1.

Reference Examples 1 and 2 A primary charging roller N119 was prepared in the same manner as in Example 1 except that the surface resistance layer was not provided in the primary charging roller of Example 1 and the internal resistance layer had a thickness of 100 μm. Manufactured.

In addition, in the primary charging roller of Example 2, the primary charging roller Na1 was prepared in the same manner as in Example 1 except that the surface resistance layer was not provided and the internal resistance layer had a film thickness of 100 μm.
O was produced.

These primary charging rollers were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 A primary charging roller Nα11 was prepared in the same manner as in Comparative Example 1 except that a resistance layer was not formed among the primary charging roller N11l.
was manufactured. This was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 An iron core with a diameter of 5 mm and a length of 250 mm was used as the axis, and 90 parts of EPDM rubber and conductive carbon (Keratsuen Black) were used.

(manufactured by Lion Corporation) and 5 parts of di-2-ethylhexyl phthalate (DOP) were melt-molded to have a diameter of 30 mm and a length of 230 mm, and an elastic layer with a thickness of 12.5 mm was provided.

The rubber hardness of this elastic layer is 45°, and the volume resistivity is 9.
X 10”Ω·cm.

Next, 95 parts of EPDM rubber, 5 parts of conductive carbon (Ketzen Black, manufactured by Liono), and 5 parts of di-2-ethylhexyl phthalate (DOP) were added to 400 parts of monochlorobenzene.
After drying this coating liquid on the elastic layer, a conductive layer was provided so that the film thickness was 20 μm.
A second charging roller Nα12 was manufactured. Example 1
Table 1 shows the results of measurement and evaluation in the same manner as above.

Comparative Example 3 Among the primary charging rollers of Comparative Example 2, primary charging roller NQ1 was prepared in the same manner as Comparative Example 2 except that no conductive layer was provided.
3 was manufactured.

The results were measured and evaluated in the same manner as in Example 1.
Shown in the table.

As is clear from the results in Table 1, the charging member of the present invention has no image defects and can provide good image quality. Also, no leakage occurs due to pinholes. Furthermore, the presence of the internal resistance layer further increases the flexibility of the charging member, thereby suppressing the amount of noise caused by the applied voltage.

Example 16 Charging member Na 1-8. 12. No. 13 was left in the copying machine for two days without operation.

As a result, in the charging members N[l12 and Na13, the plasticizer in the surface layer of the charging member oozed out, and the charging member and the photoreceptor were attached. Furthermore, when I tried to drive it to make a copy, the photosensitive layer on the attached part peeled off.

On the other hand, for charging members N[11 to 8], the charging member and the photoreceptor did not adhere to each other, and good copy images were obtained.

〔Effect of the invention〕

As described above, the charging member of the present invention has uniform charging ability and can produce good images. Further, leakage due to pinholes does not occur. Further, the amount of noise caused by the applied voltage can be suppressed. Furthermore, it does not affect the photoreceptor due to seepage or the like.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the charging member of the present invention in the direction perpendicular (a) and parallel to the axial direction of the conductive substrate, and FIG. 2 is a schematic diagram of charging a photoreceptor using the charging member. 3 and 4 are schematic cross-sectional views showing the layer structure of an electrophotographic photoreceptor, and FIG. 5 is a schematic cross-sectional view of an electrophotographic apparatus using a charging member. l... Charging member, 2... Conductive base, 3... Elastic layer, 4... Conductive layer resistance layer, 5a... Internal resistance layer,
5b...Surface resistance layer 2 Figure Figure

Claims (1)

[Claims] (1) A charging member comprising an elastic layer, a conductive layer, and a resistance layer upward from the surface of a conductive substrate, and the resistance layer has a laminated structure of an internal resistance layer and a surface resistance layer.