JP5515247B2 - Corona charger and image forming apparatus - Google Patents

Description

  The present invention relates to a corona charger, and more particularly to a corona charger that generates a negative corona and an image forming apparatus equipped with the corona charger.

In general, an electrophotographic apparatus irradiates a uniformly charged photoconductor with writing light modulated by image data to form an electrostatic latent image on the photoconductor, and this electrostatic latent image is formed. Toner is supplied to the photoreceptor by a developing unit, and a toner image is formed on the photoreceptor and developed. The image forming apparatus transfers the toner image on the photosensitive member to transfer paper (recording paper or intermediate transfer member) at the transfer portion, and then heats and pressurizes the toner transferred onto the transfer paper at the fixing portion to fix the toner image. The toner remaining on the body surface is collected by a method such as scraping with a cleaning blade at the cleaning unit. The image forming process as described above is taken.
Here, a corona charger is used as means for charging the photosensitive member which is a member to be charged.

  Corona discharge is a sustained discharge caused by local air breakdown that occurs in a non-uniform electric field. In general, the structure is such that a small diameter wire is stretched in a shield case such as aluminum and a part of the shield case is deleted. Corona ions are released from the deleted region. As the voltage applied to the corona wire is increased, a strong local electric field is formed around the wire, causing partial breakdown of air and sustaining the discharge. This is corona discharge.

  The discharge mode of corona discharge greatly depends on the polarity of the applied voltage. In the case of normal corona discharge, a uniform discharge is formed on the corona wire surface. In the case of negative corona discharge, a discharge form in which streamer discharge is scattered is obtained. The positive corona discharge has fairly good charging uniformity, but the negative corona causes discharge unevenness and is inferior to the positive corona. In addition, the amount of ozone generated by the discharge is about an order of magnitude greater in the negative corona than in the positive corona, and the burden on the environment is greater.

<Corona charger and its features>
(1) Corotron type corona charger
FIG. 1A shows a configuration of a corotron type corona charger and a charging method using the same. The corotron-type corona charger has a structure in which a tungsten wire having a diameter of 50 to 100 μm is shielded with a metal about 1 cm apart. A high voltage of 5 to 10 kV is applied to the corona wire in a state where the opening surface is arranged to face the member to be charged, and positive or negative ions generated thereby are moved to the surface of the member to be charged and charged. As shown in FIG. 2 (a), the corotron type corona charger generates a certain amount of charge, and is not necessarily good at uniformly charging the surface of the object to be charged at a constant potential. It is particularly effective as a transfer charger intended to give a constant charge to the recording paper.

(2) Scorotron-type corona charger The scorotron-type corona charger has been devised in order to reduce the unevenness of the charged potential on the surface of the object to be charged. As shown in FIG. 1B, several wires or meshes are arranged as grid electrodes on the opening surface of the corotron. The opening surface of the scorotron charger is made to face the member to be charged, and a bias voltage is applied to the grid electrode.
FIG. 2B shows charging characteristics of the scorotron type corona charger. A feature of the scorotron type corona charger is that the charging potential is regulated by the voltage applied to the grid electrode even when the charging time is long, and the surface potential is saturated. This saturation value can be controlled by the grid applied voltage. The scorotron-type corona charger has a complicated structure and inferior charging efficiency as compared with the corotron-type, but is excellent in uniformity of charging potential and widely used. The grid electrode in the electrophotographic image forming apparatus is called a charging grid.

Various investigations have been made on the alteration of the surface of an object to be charged by nitrogen oxides generated by a corona charger.
In Patent Document 1, a SUS material charging grid of a corona charger is coated with a conductive paint containing graphite particles, nickel particles, aluminum compound particles and an organic resin binder, and corrosion caused by discharge products of the control electrode is prevented. The conductive film absorbs the generated discharge product and suppresses contamination of the object to be charged. The fine particles in the film use the action of absorbing the discharge product, but the amount that can be absorbed is determined by the number of adsorption sites of the particles, so the adsorption sites are quickly buried when used over time. The effect is expected to fade.

  In the present invention, zeolite is mainly used to reduce discharge products. As a similar example, in Patent Document 2, an opening is provided in a corona charger, and ozone adsorption is performed in a finely divided communication opening installed there. Ozone diffusion is suppressed by forming a particle layer. Zeolite and activated carbon are used for the ozone adsorption particles. According to the present invention, it is possible to suppress the diffusion of ozone, but the charged object contamination by the ozone diffusing to the charged object side cannot be suppressed, so that the effect on the image cannot be expected to be effective.

  Further, in Patent Document 3, in addition to the product removing means for adsorbing the discharge product attached to the surface of the member to be charged, the product adhesion preventing means for making it difficult for the discharge product to adhere to the surface of the member to be charged; At least one of a resistance reduction preventing means for preventing the discharge product adhering to the resistance from lowering and a product generation preventing means for reducing the amount of discharge product generated near the surface of the charged body. Although there is an example in which an adsorbent such as zeolite is arranged between the charged object and the corona charger, another discharge product adsorbing means may be brought into contact with the charged object. It is essential and a plurality of members are required. Further, when the adsorbent is disposed between the charged body and the corona charger, it is expected that charging of the charged body becomes unstable.

Further, in Patent Document 4, in order to provide an image forming apparatus capable of efficiently reducing the concentrations of ozone and NOx, which are discharge products generated in the vicinity of a charger such as a charging unit and a transfer unit, a discharge is performed on the surface facing the discharge wire. By having a photocatalytic substance (semiconductor such as titanium oxide) to decompose the product, ozone and NOx, which are discharge products generated near the discharge site such as the charging part, are efficiently decomposed and the concentration is lowered. However, it is expected that the ability to decompose the discharge products will be insufficient for long-term use.

Further, Patent Document 5 prevents degradation in image quality such as resolution reduction, image flow, and non-uniform image even in a high humidity environment, enhances the durability of the photoreceptor, and further generates ozone and nitrogen oxides. In order to prevent this, it has been proposed to use a charging member mainly composed of activated carbon fibers as a material having catalytic action and conductivity. It is expected that the adsorbing ability of the object will be reduced and the adhesiveness will be lowered when a coating film is formed on the charging grid.
Further, Patent Document 6 proposes an image forming apparatus having a corona discharge charging device in which a charging device is located on the lower side of a photoreceptor and a member having adsorption and catalytic action is attached to a back surface portion. Since the corona product adhering to the inside of the charging device disposed on the lower side of the photoconductor is diffused upward, that is, on the photoconductor side, the effect is expected to be insufficient.

JP 2005-227470 A Japanese Utility Model Publication No. 62-089660 JP 2003-43894 A JP 2001-075338 A JP 2002-278223 A JP 2003-091143 A

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a corona charger that can suppress contamination of the environment and an object to be charged by reducing the amount of discharge products generated by discharge.

As a result of diligent investigations to solve the above-mentioned problems, the present inventor has reduced the discharge products generated from the corona charger, thereby preventing air pollution and photosensitivity when used in an electrophotographic electrophotographic apparatus. It has been found that the deterioration of the body can be prevented, the occurrence of density unevenness and image flow directly under the charger can be suppressed, and the reliability of the electrophotographic apparatus can be remarkably improved.
That is, the present invention is a corona charger and an image forming apparatus as described below.

(1) In a corona charger having a corona discharge electrode and a charging grid, the charging grid has a layer containing a zeolite, a conductive agent and a binder resin on the surface, and the crystal type of the zeolite is X type or Y type And when the zeolite crystal type is X type, the cation species of the zeolite is sodium, and when the zeolite crystal type is Y type, the cation species of the zeolite is sodium or hydrogen . A corona charger characterized by being.
(2) The corona charger according to (1), wherein the conductive agent is activated carbon.
(3) The corona charger according to (1), wherein the conductive agent is a metal oxide.
(4) The corona charger according to (3), wherein the metal oxide is tin oxide.
(5) The corona charger according to (3), wherein the metal oxide is zinc antimonate.
(6) The corona charger according to any one of (1) to (5), wherein the binder resin is a thermosetting resin.
(7) The corona charger according to (6), wherein the binder resin is an alkyd melamine resin.
(8) The content of zeolite is in the range of 20 to 50 wt% when the total amount of zeolite, conductive agent and binder resin forming the layer is 100 wt%. (1) to (7) The corona charger according to any one of the above.
(9) The content of the conductive agent is in the range of 20 to 50 wt% when the total amount of zeolite, conductive agent and binder resin forming the layer is 100 wt% (1) to (7) The corona charger according to any one of the above.
(10) The binder resin content is in the range of 10 to 60 wt% when the total amount of zeolite, conductive agent and binder resin forming the layer is 100 wt% (1) to (7) The corona charger according to any one of the above.
(11) The corona charger according to any one of (1) to (10), an electrophotographic photosensitive member, and at least one or more of image exposure means, development means, transfer or separation means, and cleaning means. A process cartridge which is manufactured in combination and is detachably installed in the main body of the image forming apparatus.
(12) An image forming apparatus using the corona charger according to any one of (1) to (10).

  In a scorotron type discharge corona charger having a charging grid that allows easy control of the surface potential of the object to be charged, the charging grid has a layer containing zeolite, conductive agent, and binder resin on the surface. A stable image can be maintained by reducing the amount of discharge products to be generated and suppressing deterioration of a charged body such as a photoreceptor.

  FIG. 3 is a schematic diagram showing a configuration example of the electrophotographic apparatus. The charging device 101 charges the photosensitive member 100 with (±) 600 to 1400V. After the charge is applied (charged), the image exposure system 102 forms a latent image. In the case of an analog copying machine, the original image irradiated by the exposure lamp is projected onto the photosensitive member in the form of a reverse image by a mirror and formed into an image. In the case of a digital copying machine, it is read by a CCD (Charge Coupled Device). The obtained original image is converted into a digital signal of an LD or LED having a wavelength of 400 to 780 nm, and formed on the photosensitive member. Therefore, the analog and digital wavelength ranges are different. By image formation, charge separation is performed in the photosensitive layer, and a latent image is formed on the photosensitive member.

  The photoreceptor 100 on which the latent image is formed according to the document is developed with a developer by the developing device 103, and the document image is visualized (toner image). Next, the toner image on the photoreceptor is transferred to the copy sheet 109 by applying a voltage to the transfer device 104. The voltage applied in the transfer is controlled by constant current so that the current flowing through the photosensitive member is constant. On the other hand, after the transfer, the toner image is cleaned and cleaned by the cleaning device 105 (comprising the cleaning brush 106 and the elastic rubber cleaning blade 107). Since the latent image (original image) after the toner image is formed is held on the photosensitive member after cleaning, the static eliminator (generally using red light) 108 for erasing and uniformizing. Then, the preparation for the next latent image formation is completed and a series of copying processes is completed.

The image forming unit may be fixedly incorporated in a copying apparatus, a facsimile machine, or a printer, but may be incorporated in the apparatus in the form of a process cartridge and detachable.
The process cartridge for an image forming apparatus is an apparatus that incorporates an image carrier, and further includes at least one of a charging device, a developing device, a transfer unit, a cleaning unit, and a charge eliminating unit, and is detachable from the image forming apparatus main body. (Parts).

[Problems caused by discharge products]
<Environmental impact>
It is known that when a corona charger that performs negative corona discharge is used, a substance in the air reacts by discharge to generate a substance called a discharge product. It contains ozone (O ₃ ) in which oxygen is oxidized, and nitrogen oxides (NOx) such as nitrogen monoxide (NO) and nitrogen dioxide (NO ₂ ) in which nitrogen is oxidized by ozone. Ozone is a substance that feels odor at about 0.1 ppm and adversely affects the respiratory system. Nitrogen oxide (NO ₂ ) has an adverse effect on human respiratory organs, and the daily average of hourly values is determined to be 0.04 to 0.06 ppm or less according to environmental standards. In addition, nitrogen oxides are converted into a substance called photochemical oxidant (O _x ) by a photochemical reaction caused by ultraviolet rays, and the environmental standard is also set to 0.06 ppm or less for this substance. The amount of each discharge generated is several tens of ppm for ozone and several ppm for nitrogen oxides. The current copying machine uses a filter such as activated carbon to reduce the amount discharged outside the machine.

<Influence on print quality>
(Uneven density directly under the corona charger)
As a problem caused by the discharge product generated from the corona charger, first, there is density unevenness directly under the corona charger due to standing after a long discharge. This occurs at the time of discharge during image forming operation, and the discharge product attached to the inner wall of the corona charger gradually contaminates the charged object while the device is stopped. This is a problem in that a difference occurs in the surface potential in this portion, resulting in image density unevenness. This problem occurs more prominently in a low humidity environment of about 20% RH, and gradually recovers when placed in a normal temperature and normal humidity environment. It has been confirmed that the surface of the object to be charged reacts reversibly with the discharge product, and the potential difference is generated because the capacitance increases or the resistance decreases. Although the occurrence has been confirmed in any of the photoreceptors, the occurrence is particularly remarkable in a photoreceptor having a cross-linkable cured film on the surface as a protective layer.
FIG. 4A is a diagram showing the state of an image when density unevenness directly under the corona charger occurs, and FIG. 4B is a diagram showing the photoreceptor surface potential corresponding to the image.

(Image Flow [Image Blur])
In an image forming apparatus using an electrophotographic method such as a copying machine, resolution decreases due to image flow (or image flow, image blur, etc.) as long as a charging method with discharge is used.
Although the image flow depends on the paper dust adhesion and the usage environment, the main factor is the discharge product, and the invention of a charging method that does not discharge ozone, NOx, etc. in order to be released from the image flow. It is almost impossible at present unless it is done. The image flow caused by the above factors can be improved by polishing the causative substance to the minimum necessary or by heating if it cannot be polished, but there are problems such as a decrease in the life of the photoreceptor, power and space, and control means. It becomes. Since the generation of image blur is suppressed by actively shaving the surface of the charged body, it is necessary to remove the discharge products adhering to the surface in order to suppress the image flow. Since a highly durable object has a small amount of wear, it is difficult to remove the causative substance.
In order to improve the image flow, it is necessary to take steps according to the situation. For that purpose, it is important to grasp the situation of the image flow and to solve it by taking appropriate measures.

  The discharge product first adheres in the form of spots (stains) and gradually expands over the entire surface. Even if it adheres, the image does not flow initially, but if it is not removed, the adhesion area gradually increases, and a hygroscopic low-resistance layer is formed on the surface of the photoreceptor. The image flow (or image blur) phenomenon is a phenomenon in which electric charges during image formation are diffused on or near the surface of the photosensitive member, so that a normal electrostatic latent image is not formed, resulting in an image with blurry edges. That is, when an electrostatic latent image is formed, if there is a low resistance layer in the surface layer of the photoreceptor or a layer, electric charge distortion occurs in that region, and this phenomenon occurs when the electrostatic latent image is disturbed. FIG. 5 is a schematic diagram for explaining the image flow phenomenon.

When image exposure is performed after negative charging on the surface of the photoreceptor, hole-electron pairs are formed in the charge generation layer, with electrons (-) going to the conductive support and holes (+) going to the negative charge on the surface. However, if there is a low-resistance layer in the middle of movement, holes do not go straight to the surface layer but leak laterally, or if the surface layer has low resistance, it moves laterally on the free surface. . Accordingly, charge diffusion and dissipation occur, and it is difficult to form a normal electrostatic latent image. The smaller the change in resistance value, the smaller the reduction in resolution because the movement of charges is suppressed. When the change in the resistance value is large and the volume resistivity is 10 ¹² Ω · cm or less, the resolution is lost and the image is clearly displayed, and finally the image is completely lost. At this time, the potential does not become a rectangular wave potential pattern, but becomes a gradual potential pattern, and the charging potential is lowered and the image portion potential is raised, indicating a potential pattern having a low contrast potential. These phenomena worsen with time and tend to worsen with increasing humidity.
That is, in order to form a high-resolution image, it is necessary that at least the volume resistivity of the photoreceptor is on the order of 10 ¹³ (Ω · cm) or higher and the surface resistivity is on the order of 10 ¹⁵ (Ω · cm) or higher. .

(Raindrop unevenness)
In an image forming apparatus using a scorotron charger that performs corona discharge, raindrop-like unevenness as shown in FIG. 6 may occur in the output image (thin vertical lines in the halftone are raindrop-like unevenness). This is due to the presence of large unevenness in the charge amount in a small range in charging the photosensitive member by the charger. This unevenness is caused by, for example, defective discharge due to local adhesion of the toner adhering to the charging wire, silica as its additive, or the discharge product, or a similar substance having high electric resistance adheres to the charging grid and is discharged. The generated charge does not flow through the grid and the amount of movement to the photoconductor increases, or the charged grid itself increases in electrostatic capacity, and the surface potential of the photoconductor rises locally above the voltage applied to the charge grid. It can be considered.

(Problems directly under the corona charger)
In order to reduce the discharge products discharged outside the machine, it is effective in the form of being supported by a filter etc. in the path to discharge, but the most contaminated by the discharge products is the charged object directly under the corona charger In many cases, the corona charger and the body to be charged are fixed at a fixed interval of about 1 to 2 mm for stable charging. Therefore, in order to suppress contamination of the object to be charged by the discharge product, a complicated mechanism such as inserting a shield between the corona charger and the object to be charged after discharge or moving the corona charger and object to be charged is necessary. is there. The object of the present invention is to suppress contamination of a charged object without the need for the above mechanism by holding zeolite on a charging grid.

[Configuration of photoconductor]
Next, the electrophotographic photosensitive member will be described with reference to the drawings.
FIG. 7A is a sectional view showing the electrophotographic photosensitive member of the present invention. FIG. 7A shows a photoreceptor having a laminated structure in which a charge generation layer (32) having a charge generation function and a charge transport layer (33) having a charge transport material function are laminated on a conductive support (31). FIG. 7B shows a photoreceptor in which a protective layer (34) is further laminated on the charge transport layer.

<About conductive support>
As the conductive support (31), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium is deposited or sputtered to form film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. After conversion, a tube that has been subjected to surface treatment such as cutting, superfinishing, or polishing can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 58-86547 can also be used as the conductive support (31).
In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) of the present invention.

Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin.
Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support (1) of the present invention.

<About photosensitive layer>
(Charge generation layer)
The charge generation layer (32) is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as necessary. As the charge generation material, inorganic materials and organic materials can be used.

  Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  Binder resins used as necessary for the charge generation layer (32) include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-. Examples thereof include vinyl carbazole and polyacrylamide. These binder resins can be used alone or as a mixture of two or more. In addition to the binder resin described above as a binder resin for the charge generation layer, a polymer charge transport material having a charge transport function, such as an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, a pyrazoline skeleton, etc. Polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin, polymer materials having a polysilane skeleton, and the like can be used.

The charge generation layer (32) can contain a low molecular charge transport material.
Examples of the low molecular charge transport material that can be used in the charge generation layer (32) include a hole transport material and an electron transport material.
Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.

The method for forming the charge generation layer (32) mainly includes a vacuum thin film preparation method and a casting method from a solution dispersion system.
As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed.
In addition, in order to provide the charge generation layer by the latter casting method, the inorganic or organic charge generation material described above, together with a binder resin, if necessary, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclohexane. Can be formed by dispersing with a ball mill, attritor, sand mill, bead mill, etc. using a solvent such as pentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc. . Moreover, leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, can be added as needed. The application can be performed by dip coating, spray coating, bead coating, ring coating, or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

(Charge transport layer)
The charge transport layer (33) is a layer having a charge transport function. A charge transport material having a charge transport function and a binder resin are dissolved or dispersed in an appropriate solvent, and this is coated on the charge generation layer (32) and dried. To form. As the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer (32) can be used.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resins and alkyd resins.

The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it can be used alone or in combination with a binder resin.
As the solvent used for coating the charge transport layer, the same solvent as that used for the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin well is suitable. These solvents may be used alone or in combination of two or more. The charge transport layer (33) can be formed by the same coating method as the charge generation layer (32).

If necessary, a plasticizer and a leveling agent can be added.
As a plasticizer that can be used in combination with the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.
Leveling agents that can be used in combination with the charge transport layer include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount used is a binder resin. About 0 to 1 part by weight is appropriate for 100 parts by weight.
The thickness of the charge transport layer is suitably about 5 to 40 μm, preferably about 10 to 30 μm.

(Protective layer)
By providing the protective layer (34) on the charge transport layer, wear resistance and durability against scratches can be improved. The protective layer includes those in which conductive fine particles are dispersed, those in which lubricating fine particles such as a fluorine-containing resin and an acrylic resin are dispersed, and those made of a crosslinked film having excellent mechanical strength. Examples of this resin are preferably phenol resin, urethane resin, melamine resin, curable acrylic resin, siloxane resin, and the like. Further, the protective layer preferably contains a charge transport material in order to improve its electrical characteristics. In addition, as a charge transport material, what was mentioned as a constituent material of the said charge transport layer can be used, for example.

[Charging grid of corona charger]
<Charging grid substrate>
As the base material of the charging grid which is the control electrode of the corona charger, those conventionally used can be used. As a material of the charging grid, a metal which is a conductor is used to function as an electrode. Most of the metals such as aluminum, nickel, iron, nichrome, copper, zinc, and silver can be used as the electrode function, but the charger is exposed to ozone, NOx, etc. generated by corona discharge. A metal having high corrosion resistance is preferable, and stainless steel containing chromium or nickel is used. As the shape, it is necessary to move the charge generated by corona discharge onto the photoconductor and to have a function as a control electrode, so that a metal thin plate is provided with an opening by punching, etching or the like, or metal wires are arranged Is usually used.
As a base material for the control electrode used this time, a SUS304 plate having a thickness of 0.1 mm, a length of 285 mm, and a width of 40 mm is used, and an opening length of 250 mm and a width of 36 mm is formed by a 0.1 mm grid at a 45 degree angle. Used at intervals of 0.5 mm.
The appearance of the charging grid used in the example is shown in FIG.

<Charging grid coating film>
(Zeolite)
In the present invention, zeolite is used to remove discharge products. Zeolite is a crystal like crystal, mainly composed of aluminum and silicon. The crystals are very small and cannot be seen visually in shape or size. When enlarged, it can be confirmed that there are many pores called pores. More than 40 types of zeolite having this unique structure have been discovered in nature.
In order to make the most of the characteristics of zeolite, which is represented by the adsorption / decomposition function, industrially produced zeolite is called synthetic zeolite. Synthetic zeolites have many types that are high in performance and are not found in natural zeolites, but their cost is a disadvantage.
Artificial zeolite has emerged as the third zeolite. By treating materials that were considered waste such as coal ash, it is converted into a zeolite that is beneficial to the earth and mankind. Moreover, because of its low cost, it is a material that is currently attracting a great deal of attention.

・ Adsorption function Zeolite has the function of adsorbing various substances, and its mechanism is similar to that of deodorizers and desiccants. By making use of this function, it is possible to adsorb harmful substances and remove malodors.
・ Cation exchange function Zeolite has a high cation exchange function of about 2 to 3 times that of natural zeolite. By utilizing this function, soil improvement to neutralize acidity and removal of ammonium ions in sewage / drainage Etc. are possible.
-Catalytic function Zeolite has a function as a catalyst, and decomposition of nitrogen oxides (NOx) and the like have been studied using this function.

The type of zeolite used in the present invention is not limited, but the size of pores varies depending on the crystal form and the type of cation, so that the molecules that can be adsorbed are different. Therefore, effective removal is possible by selecting the crystal form and cation species according to the target substance. Crystal types include A type, X type, Y type, L type, mordenite type, ferrierite type, ZSM-5 type, beta type, and cation species include potassium, sodium, calcium, ammonium, hydrogen, etc. is there. Further, the adsorption ability and catalytic ability change depending on the ratio of aluminum and silicon constituting the zeolite, and the target substance can be efficiently removed by setting the optimum ratio.
Among them, it is preferable to use zeolite whose crystal type is any of A type, X type, and Y type, and it is more preferable that the cationic species is any of potassium, sodium, and calcium.
These types of zeolites have a particularly high discharge product removal effect after a long discharge.

(Binder resin)
A binder resin is used for the purpose of holding the zeolite on the charging grid. The binder resin can be used regardless of natural resin or synthetic resin. Examples of synthetic resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride. , Vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, Thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin and the like can be mentioned. The coating film is required to have durability against electric discharge and adhesion with a binder resin, but a binder resin ratio in a range in which the discharge product removal effect is not hindered by covering the zeolite surface is desirable. Therefore, it is preferable because the adhesiveness is good at a binder resin ratio with less thermosetting resin that forms a network structure by a polymerization reaction by heat. In some cases, two types of binder resins can be used.
The binder ratio that the discharge product removal function does not deteriorate due to the binder resin covering the zeolite was normally about 10 wt%, but the evaluation was performed even when the binder resin ratio was around 30 wt%. It has been confirmed that the function is not lowered and compatibility with adhesion is possible.

(Conductive agent)
A charged grid base material made of a processed product of a wire or a metal plate is inherently conductive, but since it is covered with zeolite and a binder resin, the electric resistance is increased and does not play a role of controlling the surface potential. Therefore, a conductive agent is dispersed in the binder resin for the purpose of imparting conductivity.
Here, the conductive agent includes metal fine particles such as graphite, nickel, copper, and silver, metal oxides such as antimony-doped tin oxide (ATO), indium tin oxide (ITO), tin oxide, and zinc antimonate, and activated carbon. Such conductive particles can be used. Since charged grids are always placed under discharge during use, the materials used must be resistant to discharge, and metals such as graphite and nickel, and undoped metal oxides such as tin oxide and zinc antimonate are used over time. It is preferable because it is stable against environmental fluctuations. In addition, the smaller the content of the conductive agent, the more the conductivity of the particle itself and the smaller the particle size are, since the other functions are not hindering the adhesion of the film and the discharge product removing function. In the present invention, conductive fine particles having a particle diameter of 0.01 mm to 15 mm are used. A conductive binder resin can also be used as a conductive agent. In some cases, two kinds of conductive agents can be used.

<Coating method on the charging grid>
The coating liquid was first prepared by adding a binder resin to a ratio of about 5 to 10 wt% with respect to the solvent, and adding zeolite particles and a conductive agent while stirring. In the case of spray coating, the solid concentration of the coating liquid was 30 wt% or less.
As a method for coating the prepared liquid on the charging grid, there are a dipping method, a roller coating method, an electrophoretic electrodeposition method, and the like, but this time, the spray method with the least coating unevenness was used. A charging grid is tensioned from both ends in the long axis direction and installed in the longitudinal direction of a cylindrical base having a diameter of 30 mm, and the cylinder is rotated at a speed of 170 rpm in the circumferential direction and sprayed in the horizontal direction at 10 mm / sec. Coating was carried out by scanning at a speed of. In order to coat both sides, a charging grid was installed about 3 mm above the base. After spray coating, the membrane was fixed by heating at 130 ° C. for 30 minutes and drying.
The coating was carried out one side at a time, and after the coating on one side was completed and allowed to stand for 10 minutes, the opposite side was coated. The coating film thickness was 30 μm.
When the base material of the charging grid is a wire, a uniform coating film is formed around the wire.
In the above, a coating film was formed using a coating film-forming material containing a conductive agent, but after forming a coating film using a coating film-forming material consisting of a binder resin and zeolite, a conductive agent was applied or driven in later A coating film may be formed.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. The “parts” used in the photoconductor production examples all represent parts by weight.
Examples are Examples 31, 32, and 34. Examples 1 to 30, 33 and Reference Examples 31, 32, and 34 are missing numbers.

<Photoconductor Preparation Example 1>
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution in the following order on a φ100 mm aluminum cylinder in sequence, an undercoat layer of 3.5 μm Then, a 0.2 μm charge generation layer and a 32 μm charge transport layer were formed to obtain a photoreceptor 1.

[Coating liquid for undercoat layer]
Alkyd resin 6 parts (Beckosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide 40 parts Methyl ethyl ketone 50 parts

[Coating liquid for charge generation layer]
Y-type titanyl phthalocyanine 6 parts Silicone resin solution 70 parts (KR5240, 15% xylene-butanol solution: Shin-Etsu Chemical Co., Ltd.)
2-butanone 200 parts

[Coating liquid for charge transport layer]
Charge transport material (Structural formula A below) 25 parts Bisphenol Z-type polycarbonate 30 parts (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company)
1,2-dichloroethane 200 parts

<Photoconductor Preparation Example 2>
A 22 μm charge transport layer was formed on the charge transport layer of the photoreceptor preparation example 1 with a charge transport layer coating solution having the following composition, and a crosslinkable charge transport layer coating solution having the following composition was sprayed on the charge transport layer. After coating and natural drying for 20 minutes, the coating film was cured by light irradiation under the conditions of metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 500 mW / cm ² , irradiation time: 60 seconds. Further, a photoconductor 2 was prepared in the same manner as the photoconductor 1 except that drying was performed at 130 ° C. for 20 minutes to provide a 5.2 μm cross-linked charge transport layer.

[Coating liquid for charge transport layer]
Charge transport material (Structural formula A below) 20 parts Bisphenol Z-type polycarbonate 30 parts (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company)
1,2-dichloroethane 200 parts

[Coating liquid for cross-linked charge transport layer]
Trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure 10 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
10 parts of a polymerizable compound having a charge transporting structure represented by the following structural formula
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

<Photoreceptor Preparation Example 3>
After coating on a 360 mm long, φ100 mm aluminum cylinder using a coating solution for charge blocking layer having the following composition, drying was performed at 130 ° C. for 20 minutes to form a charge blocking layer of about 0.5 μm. Subsequently, after applying using a coating solution for a moire preventing layer having the following composition, drying was performed at 130 ° C. for 30 minutes to provide a 3.5 μm moire preventing layer. Subsequently, after coating using a coating solution for charge generation layer having the following composition, drying was performed at 100 ° C. for 20 minutes to form a charge generation layer of about 0.2 μm. Furthermore, after coating using a coating solution for a charge transport layer having the following composition, drying was performed at 130 ° C. for 20 minutes to form a charge transport layer having a thickness of about 20 μm. All the coatings so far used the dip coating method. After applying the coating solution for the crosslinked surface layer having the following composition to the photoreceptor obtained as described above by spray coating, using a Ushio UV lamp system, photocuring is performed with a UV irradiation time of 60 seconds, Further, by drying at 70 ° C./30 minutes, a crosslinked surface layer of about 7 μm was provided.

[Charge blocking layer coating solution]
N-methoxymethylated nylon (manufactured by Lead City, FR101) 5 parts Methanol 70 parts n-butanol 30 parts

[Moire prevention layer coating solution]
Titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., CR-EL) 126 parts Alkyd resin (manufactured by Dainippon Ink and Chemical, Beckolite M6401-50-S) 33.6 parts Melamine resin (manufactured by Dainippon Ink and Chemicals, Super Becamine L -121-60) 18.7 parts 2-butanone 100 parts

[Coating liquid for charge generation layer]
Y-type titanyl phthalocyanine 6 parts Silicone resin solution (manufactured by Shin-Etsu Chemical, KR5240) 70 parts Methyl ethyl ketone 200 parts

[Coating liquid for charge transport layer]
Polycarbonate Z polycarbonate (manufactured by Teijin Chemicals) 10 parts Charge transporting compound represented by the following structural formula 7 parts

Tetrahydrofuran 80 parts Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF50-100cs) 0.002 parts

[Coating liquid for cross-linked surface layer]
10 parts of trifunctional acrylic resin (manufactured by Nippon Kayaku, KAYARAD TMPTA) 10 parts of a polymerizable compound having a charge transporting structure represented by the following structural formula
Polymerization initiator (Ciba Specialty Chemicals, Irgacure 184) 1 part Tetrahydrofuran 50 parts

[ Reference Example 1]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / conductive agent / binder resin was 5/3/2, and the solid content concentration of the liquid was adjusted to 30 wt%.
Zeolite: β-type zeolite containing hydrogen ions (980HOA manufactured by Tosoh Corporation)
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 Dainippon Ink Chemical
(Alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone The above coating solution was applied to a charging grid of a corona charger by spraying, and the following evaluation was performed.

[Evaluation method of corona charger]
(1) Evaluation of film adhesion The coating surface of the coating applied to the charging grid should be able to withstand actual use. Evaluation was based on the degree of peeling when wiped. Moreover, after discharging a corona charger for 200 hours as durability evaluation, it evaluated similarly. The degree of each symbol is shown below.
◎ ・ ・ ・ Does not adhere to waste even if rubbed strongly
○ ・ ・ ・ Applicable to actual use when it is rubbed hard ○ △ ・ ・ ・ Applicable to actual waste when it is rubbed normally It adheres to the waste and cannot withstand actual use.

(2) Evaluation of charge controllability The charge grid was attached to an Image Neo 1050pro placed in a 10 ° C. and 15% RH environment. Corona discharge was performed by applying a voltage so that a constant current would flow through the charging wire, and the surface potential of the photoreceptor to be charged when -900 V was applied to the charging grid was measured. After that, a halftone image was output, and the presence or absence of raindrop-like unevenness that occurred at the time of local charging failure was confirmed.
◎ ・ ・ ・ No raindrop unevenness
○ ・ ・ ・ Weeping unevenness slightly occurs, but acceptable level × ・ ・ ・ Raining unevenness

(3) Evaluation of discharge product removal function The charging grid was attached to an Image Neo 1050pro placed in a 10% C 15% RH environment. By performing the image forming operation, the corona charger was discharged for 3 hours, and then the machine was turned off and left for 15 hours. The machine was turned on again, the amount of surface potential drop immediately below the corona charger was measured, and halftone (halftone) image output was used to check for the occurrence of density unevenness immediately below the corona charger.
◎ ... Concentration unevenness directly under the corona charger does not occur ○ Concentration unevenness directly under the corona charger occurs, but acceptable level △ ... Concentration unevenness directly under the corona charger appears to an acceptable level × ... Uneven level of density unevenness right under the corona charger

For the evaluations (2) and (3) in Reference Examples 1 to 27 and Comparative Examples 1 to 5, the photoreceptor 2 having a protective layer on the outermost layer was used.
In the evaluations (2) and (3) in Reference Examples 28 and 29 and Comparative Examples 6 and 7, the photoreceptor 2 without a protective layer was used.
For the evaluations (2) and (3) in Reference Examples 30 to 36, 37 to 42, and Comparative Examples 8 to 11 and 12 to 15, the photoreceptor 3 having a protective layer as the outermost layer was used.

[ Reference Example 2]
A sample similar to that of Reference Example 1 was prepared and evaluated except that activated carbon (RP-20, manufactured by Kuraray Chemical) was used as a conductive agent.
[ Reference Example 3]
A sample similar to Reference Example 1 was prepared and evaluated except that tin oxide (S2000 manufactured by Mitsubishi Materials) was used as the conductive agent.
[ Reference Example 4]
A sample similar to that of Reference Example 1 was prepared and evaluated except that indium tin oxide: ITO (SUFP manufactured by Sumitomo Metal Mining) was used as the conductive agent.
[ Reference Example 5]
A sample similar to Reference Example 1 was prepared and evaluated except that antimony-doped tin oxide: ATO (manufactured by TWU-1 Gemco) was used as the conductive agent.
[ Reference Example 6]
A sample similar to Reference Example 1 was prepared and evaluated except that only an alkyd resin (Beckosol 1307-60-EL manufactured by Dainippon Ink & Chemicals, Inc.) was used as the binder.

[ Reference Example 7]
A sample similar to Reference Example 1 was prepared and evaluated except that only a melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.) was used as the binder.
[ Reference Example 8]
A sample similar to Reference Example 1 was prepared and evaluated except that only a polyurethane resin (Nipporan 3022 manufactured by Nippon Polyurethane Industry) was used as a binder.
[ Reference Example 9]
A sample similar to Reference Example 1 was prepared and evaluated except that only an epoxy resin (made by 827 JER) was used as a binder.
[ Reference Example 10]
A sample similar to Reference Example 1 was prepared and evaluated except that only a polyethylene resin (manufactured by WAKO) was used as a binder.
[ Reference Example 11]
A sample similar to Reference Example 1 was prepared and evaluated except that only a polystyrene resin (manufactured by WAKO) was used as a binder.

[ Reference Example 12]
A sample similar to Reference Example 1 was prepared and evaluated except that only bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) was used as the binder.
[ Reference Example 13]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was set to 7/2/1.
[ Reference Example 14]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 5/2/3.
[ Reference Example 15]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 2/2/6.

[ Reference Example 16]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was set to 5/4/1.
[ Reference Example 17]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 4/5/1.
[ Reference Example 18]
A sample similar to that of Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was set to 8/1/1.
[ Reference Example 19]
A sample similar to Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 1/5/4.
[ Reference Example 20]
A sample was prepared and evaluated in the same manner as in Reference Example 1 except that the weight ratio of zeolite / conductive agent / binder resin was 3/6/1.

[ Reference Example 21]
A sample similar to Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 2.5 / 1 / 6.5.
[ Reference Example 22]
A sample similar to Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 8.5 / 1 / 0.5.
[ Reference Example 23]
Reference Example 1 except that the weight ratio of zeolite / conductive agent / binder resin was 8.5 / 1 / 0.5, and the binder resin was melamine resin (Super Becamine G-821-60 manufactured by Dainippon Ink & Chemicals, Inc.). Samples similar to those described above were prepared and evaluated.
[ Reference Example 24]
A sample similar to Reference Example 1 was prepared and evaluated except that the weight ratio of zeolite / conductive agent / binder resin was 8.5 / 1 / 0.5, and the binder resin was a polystyrene resin (manufactured by WAKO). .
[ Reference Example 25]
Reference examples except that the weight ratio of zeolite / conductive agent / binder resin is 9 / 0.5 / 0.5, the conductive agent is ATO, and the binder resin is bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company). Samples similar to 1 were prepared and evaluated.

[ Reference Example 26]
Reference example except that the weight ratio of zeolite / conductive agent / binder resin was 0.5 / 9 / 0.5, the conductive agent was ATO, and the binder resin was bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company). Samples similar to 1 were prepared and evaluated.
[ Reference Example 27]
Reference example except that the weight ratio of zeolite / conductive agent / binder resin is 0.5 / 0.5 / 9, the conductive agent is ATO, and the binder resin is bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company). Samples similar to 1 were prepared and evaluated.
[ Reference Example 28]
Samples similar to those of Reference Example 1 were prepared and evaluated using the photoreceptor 1 having no protective layer.
[ Reference Example 29]
A sample similar to Reference Example 1 was prepared except that activated carbon (RP-20 Kuraray Chemical Co., Ltd.) was used as the conductive agent, and evaluation was performed using the photoreceptor 1 having no protective layer.

[ Reference Example 30]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / conductive agent / binder resin was 5/3/2, and the solid content concentration of the liquid was adjusted to 30 wt%.
Zeolite: A-type zeolite containing sodium ions (A-4 manufactured by Tosoh Corporation)
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 Dainippon Ink Chemical
(Made by industry) (alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone The above coating solution was applied to a charging grid of a corona charger by spraying, and the following evaluation was performed.

[Example 31]
A sample similar to Reference Example 30 was prepared and evaluated except that sodium ion-containing X-type zeolite (F-9 manufactured by Tosoh Corporation) was used as the zeolite.
[Example 32]
A sample similar to Reference Example 30 was prepared and evaluated except that sodium-containing Y-type zeolite (HSZ-320NAA manufactured by Tosoh Corporation) was used as the zeolite.
[ Reference Example 33]
A sample similar to Reference Example 30 was prepared and evaluated except that sodium-containing mordenite-type zeolite (HSZ-642NAA manufactured by Tosoh Corporation) was used as the zeolite.
[Example 34]
A sample similar to Reference Example 30 was prepared and evaluated, except that hydrogen ion-containing Y-type zeolite (HSZ-320HOA manufactured by Tosoh Corporation) was used as the zeolite.
[ Reference Example 35]
A sample similar to Reference Example 30 was prepared and evaluated except that a hydrogen ion-containing mordenite-type zeolite (HSZ-690HOA manufactured by Tosoh Corporation) was used as the zeolite.
[ Reference Example 36]
A sample similar to Reference Example 30 was prepared and evaluated, except that hydrogen ion-containing beta zeolite (HSZ-940HOA manufactured by Tosoh Corporation) was used as the zeolite.

[ Reference Example 37]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / conductive agent / binder resin was 5/3/2, and the solid content concentration of the liquid was adjusted to 30 wt%.
Zeolite: A-type zeolite containing potassium ions (A-3 manufactured by Tosoh Corporation)
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 manufactured by Dainippon Ink and Chemicals) (alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone The above coating solution was applied to a charging grid of a corona charger by spraying, and the following evaluation was performed.
[ Reference Example 38]
A sample similar to Reference Example 37 was prepared and evaluated except that calcium-containing A-type zeolite (A-5 manufactured by Tosoh Corporation) was used as the zeolite.
[ Reference Example 39]
A sample similar to Reference Example 37 was prepared and evaluated except that ammonium ion-containing Y-type zeolite (HSZ-341NHA manufactured by Tosoh Corporation) was used as the zeolite.

[Comparative Example 1]
The same evaluation as in Example 1 was performed except that a corona charger having nothing applied to the charging grid was used.
[Comparative Example 2]
A sample similar to Example 1 was prepared and evaluated except that the coating liquid did not contain a conductive agent and the weight ratio of zeolite / binder resin was 9/1.
[Comparative Example 3]
A sample similar to Example 1 was prepared and evaluated except that the coating liquid did not contain a conductive agent and the weight ratio of zeolite / binder resin was 8/2.
[Comparative Example 4]
A sample similar to Example 1 was prepared and evaluated, except that the coating liquid did not contain a conductive agent and the weight ratio of zeolite / binder resin was set to 1/9.
[Comparative Example 5]
A sample similar to Example 1 was prepared and evaluated except that the coating liquid did not contain zeolite and the conductive agent / binder resin weight ratio was 9/1.
[Comparative Example 6]
The same evaluation as in Example 1 was performed using a corona charger with nothing applied to the charging grid and the photoreceptor 1 without a protective layer.
[Comparative Example 7]
A sample similar to Example 1 was prepared except that the coating liquid did not contain a conductive agent and the weight ratio of zeolite / binder resin was 9/1, and evaluation was performed using the photoreceptor 1 without a protective layer. . [Comparative Example 8]
The same evaluation as in Example 30 was performed except that a corona charger having nothing applied to the charging grid was used.

[Comparative Example 9]
A coating solution was prepared using the materials shown below. The weight ratio of conductive agent / binder resin was 8/2, and the solid content concentration of the liquid was adjusted to 30 wt%, and the same evaluation as in Example 30 was performed.
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 Dainippon Ink Chemical
(Made by industry) (alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone

[Comparative Example 10]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / binder resin was 8/2, and the solid content concentration of the liquid was adjusted to 30 wt%, and the same evaluation as in Example 30 was performed.
Zeolite: A-type zeolite containing sodium ions (A-4 manufactured by Tosoh Corporation)
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Dispersion medium: 2-butanone

[Comparative Example 11]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / conductive agent was 8/2, and the solid content concentration of the liquid was adjusted to be 30 wt%, and the same evaluation as in Example 30 was performed.
Zeolite: A-type zeolite containing sodium ions (A-4 manufactured by Tosoh Corporation)

Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 Dainippon Ink Chemical
(Alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone

[Comparative Example 12]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / binder resin was 8/2, and the solid content concentration of the liquid was adjusted to 30 wt%, and the same evaluation as in Example 37 was performed.
Zeolite: A-type zeolite containing potassium ions (A-3 manufactured by Tosoh Corporation)
Conductive agent: Zinc antimonate (Sellnax CX-Z210IP manufactured by Nissan Chemical Industries)
Dispersion medium: 2-butanone

[Comparative Example 13]
A coating solution was prepared using the materials shown below. The weight ratio of zeolite / conductive agent was 8/2, and the solid content concentration of the liquid was adjusted to 30 wt%, and the same evaluation as in Example 37 was performed.
Zeolite: A-type zeolite containing potassium ions (A-3 manufactured by Tosoh Corporation)

Binder resin: Alkyd resin (Beccosol 1307-60-EL manufactured by Dainippon Ink and Chemicals)
Melamine resin (Super Becamine G-821-60 Dainippon Ink Chemical
(Alkyd resin / melamine resin = 3/2 weight ratio)
Dispersion medium: 2-butanone

Table 1 shows the coating conditions of the coating film on the charging grid in Examples and Comparative Examples.
The evaluation results in the examples and comparative examples are shown in Table 2.
Looking at the result of the discharge product removal function, the amount of NOx generated can be reduced by using a charged grid coated with a zeolite-containing film, and the effect of removing the discharge product can be confirmed. In addition, the suppression effect can be confirmed even in the occurrence of density unevenness and image flow directly under the charger, which are problems in the image. As a member to be charged, the effect is great when a photosensitive member having a protective layer on the outermost surface is used. In addition, it turns out that the effect of a discharge product removal is high in the range of 20 to 70 wt% of zeolite. In addition, the charging grid holding only the conductive agent and the binder has almost no effect of removing the discharge products, and has no effect when used over time.

  Regarding the charge controllability, the surface potential of the object to be charged is higher than the voltage applied to the charging grid in the zeolite and binder-only film, and the charging is unstable due to unevenness in the image, but the conductive agent is dispersed. The charged grid showed the same result as the case where a charged grid with nothing applied was used, and it was confirmed that the charging was stable. The conductive agent is preferably in the range of 20 to 50 wt% from the viewpoint of charge controllability, film adhesion, and discharge product removal function.

Regarding the adhesion of the film, the strength is high when a thermosetting resin is used as the binder resin, and the maintenance of the film strength can be confirmed in continuous use by using an alkyd / melamine resin in particular. The binder resin is preferably in the range of 10 to 60 wt% from the viewpoints of film adhesion, charge controllability, and discharge product removal function.

Table 3 shows crystal types of zeolite used in the charged grid coating solutions in Reference Examples 1 to 30, 33, 35, and 36 and Examples 31, 32, and 34 .

Table 4 shows the film adhesion evaluation results in Reference Examples 30, 33, 35, and 36, Examples 31 , 32 , and 34 , and Comparative Examples 8 to 11.
As shown in Table 4, Comparative Example 10 that does not use the binder resin has poor coating adhesion from the beginning, and the film peels off due to discharge.
Moreover, it can confirm that the adhesiveness in time can be maintained by hold | maintaining a zeolite and a electrically conductive agent to a grid with binder resin.

Table 5 shows the charge controllability evaluation results in Reference Examples 30, 33, 35, and 36, Examples 31 , 32 , and 34 , and Comparative Examples 8 to 11.
According to Table 5, in Comparative Example 11 containing no conductive agent, an abnormal image was generated from the initialization, and the surface potential of the photosensitive member was significantly higher than the charging grid voltage, and the charge controllability was remarkably inferior. I understand that.

Table 6 shows the discharge product removal function evaluation results in Reference Examples 30, 33, 35, and 36, Examples 31 , 32 , and 34 , and Comparative Examples 8 to 11.
According to Table 6, the effect of removing the discharge products can be confirmed by using a charged grid coated with any zeolite-containing film. In addition, when zeolites with crystal types of A, X, and Y are used, the discharge product removal effect equivalent to the initial stage is shown even after 200 hours of discharge, and it can be confirmed that the effect is excellent in sustainability. .

Table 7 shows the zeolite-containing cations used in the charged grid coating solutions in Reference Examples 1 to 30, 33, 35 to 39, and Examples 31, 32, and 34 .

Table 8 shows the film adhesion evaluation results in Reference Examples 37 to 39 and Comparative Examples 12 to 13. As shown in Table 8, in Comparative Example 12 in which no binder resin was used, the adhesion of the coating film was poor from the beginning, and the film was peeled off by discharge.
Moreover, it can confirm that the adhesiveness in time can be maintained by hold | maintaining a zeolite and a electrically conductive agent to a grid with binder resin.

Table 9 shows the charge controllability evaluation results in Reference Examples 37 to 39 and Comparative Examples 12 to 13. From Table 9, it can be seen that Comparative Example 15 containing no conductive agent has an abnormal image since initialization, and the surface potential of the photoreceptor is significantly higher than the charging grid voltage, and the charge controllability is remarkably inferior. Recognize.

Table 10 shows the discharge product removal function evaluation results in Reference Examples 37 to 39 and Comparative Examples 12 to 13.
From Table 10, the effect of removing the discharge products can be confirmed by using a charged grid coated with any zeolite-containing film.
In addition, when zeolite containing potassium, calcium, sodium, or hydrogen is used, the discharge product removal effect is the same as the initial stage even after 300 hours of discharge, and the replacement efficiency of the discharge product is good. It can be confirmed that it is excellent in sustainability.

Since the corona charger of the present invention can reduce the amount of discharge products, it can be used in an image forming apparatus or the like to suppress the deterioration of a charged body such as a photoconductor and maintain a stable image. be able to.

It is a schematic diagram which shows the structure of a corotron type corona charger and a scorotron type corona charger. It is a figure which shows the charging characteristic of a corotron type corona charger and a scorotron type corona charger. 1 is a diagram illustrating a configuration example of an image forming apparatus of the present invention. It is a figure which shows the density non-uniformity right under a corona charger. It is a schematic diagram explaining an image flow phenomenon. It is a schematic diagram which shows a raindrop-like nonuniformity. It is a schematic diagram which shows the cross section of an electrophotographic photoreceptor. It is a figure which shows an example of the structure of a charging grid.

Explanation of symbols

1 Charger 2 Casing 3 End block (insulating)
4 End block (insulating)
6 Charging grid 8 Claw for stretching grid 9 Grid bias application electrode 9a Claw for stretching grid (bias application electrode and grid are connected)
DESCRIPTION OF SYMBOLS 31 Conductive support 32 Charge generation layer 33 Charge transport layer 34 Protective layer 100 Photoconductor 101 Charging device 102 Image exposure system 103 Development device 104 Transfer device 105 Cleaning device 106 Cleaning brush 107 Elastic rubber cleaning blade 108 Static elimination device 109 Copy paper

Claims (12)

In corona charger having a corona discharge electrode and the charging grid, the charging grid has a layer comprising a zeolite and a conductive agent and a binder resin on the surface, the crystal form of the zeolite is X-type or Y type, wherein When the zeolite crystal type is X type, the cation species of the zeolite is sodium, and when the zeolite crystal type is Y type, the cation species of the zeolite is sodium or hydrogen. Corona charger.   The corona charger according to claim 1, wherein the conductive agent is activated carbon.   The corona charger according to claim 1, wherein the conductive agent is a metal oxide.   The corona charger according to claim 3, wherein the metal oxide is tin oxide.   The corona charger according to claim 3, wherein the metal oxide is zinc antimonate.   The corona charger according to claim 1, wherein the binder resin is a thermosetting resin.   The corona charger according to claim 6, wherein the binder resin is an alkyd-melamine resin.   8. The content of zeolite is in a range of 20 to 50 wt% when the total amount of zeolite, conductive agent and binder resin forming the layer is 100 wt%. Corona charger.   8. The content of the conductive agent is in the range of 20 to 50 wt% when the total amount of zeolite, conductive agent and binder resin forming the layer is 100 wt%. Corona charger.   8. The content of the binder resin is in the range of 10 to 60 wt% when the total amount of the zeolite, the conductive agent and the binder resin forming the layer is 100 wt%. Corona charger.   The corona charger according to any one of claims 1 to 10, an electrophotographic photosensitive member, an image exposure means, a development means, a transfer or separation means, and a cleaning means are combined and produced. A process cartridge which is detachably installed in an image forming apparatus main body.   An image forming apparatus using the corona charger according to claim 1.