JP2010139582A - Scorotron type corona charger, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corona charger which can sustainably prevent contamination of environment, and contamination of a surface and inside of a charged body by reducing the amount of discharge product generated by corona discharge in the atmosphere using high voltage. <P>SOLUTION: A scorotron type corona charger having a grid where a coat layer containing at least a zeolite, a resistance control agent and a binder resin is formed, has a structure where the coat layer is formed inner side than an edge face of the grid. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a corona charging device used in an image forming apparatus using an electrophotographic system, and more particularly to a scorotron type corona charger having a grid electrode, a process cartridge using the same, and an image forming apparatus.

  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 the transfer paper or the intermediate transfer member at the transfer unit, and then fixes the toner transferred on the transfer paper by the fixing unit by heating and pressurizing, and remains on the surface of the photosensitive member. The toner 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.

It is known that a corona charger can be used as a means for charging the photoreceptor, which is the first stage of the image forming process.
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. For this reason, the positive corona discharge has fairly good charging uniformity, but the negative corona causes discharge unevenness and is inferior to the positive corona. Further, it is known that the amount of ozone generated by discharge is about one order of magnitude higher in the negative corona than in the positive corona, and the burden on the environment is greater.

Next, the corona generator and its features are described.
(1) Corotron type corona generator FIG. 1A shows the configuration of a corotron type corona generator and a charging method using it. The corotron-type corona generator 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. In a state where the opening surface is arranged opposite to the member to be charged (photosensitive member), a high voltage of 5 to 10 kV is applied to the corona wire, and positive or negative ions generated thereby are moved to the surface of the member to be charged. To do. As shown in FIG. 2A, the corotron-type corona generator generates a certain amount of charge, so that it is not necessarily good at uniformly charging the surface of an object to be charged having a film thickness deviation to a constant potential.

(2) Scorotron-type corona generator The scorotron-type corona generator has been devised in order to reduce the unevenness of the charged potential on the surface of an 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.
The charging characteristics of the scorotron type corona generator are shown in FIG. A feature of the scorotron type corona generator 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 generator has a more complicated structure and inferior charging efficiency than the corotron type, but is excellent in uniformity of charging potential and widely used.

Regardless of whether the corotron type or the scorotron type is used, the corona charger is a charger that uses a high-pressure discharge of 5 to 10 kV in the atmosphere. It is known to generate and release ₃ , NOx, and discharge products such as nitrate ions and ammonium ions. These discharge products may adhere to and permeate the photoreceptor, which is a member to be charged, and may cause problems such as white spots, black belts, and image blur on the image. When a corona charger is used, a technique for preventing deterioration of the photoreceptor due to discharge products is sometimes required, and various studies have been conducted.

  In Patent Document 1, a SUS material charging grid of a corona generator is applied 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 Patent Document 2, an opening is provided in a corona generator, and ozone diffusion is suppressed by forming an ozone-adsorbing particle layer in a finely divided communication opening provided there. 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. Therefore, the effect affecting the image cannot be expected.

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 disposed between a charged object and a corona generator, 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 generator, it is expected that the charging of the charged body becomes unstable.
JP 2005-227470 A Japanese Utility Model Publication No. 62-089660 JP 2003-43894 A

  The present invention has been studied in view of the above circumstances, and by reducing the amount of discharge products generated by corona discharge using high pressure in the atmosphere, the environment and surface / internal contamination of the object to be charged are maintained. The main object of the present invention is to provide a corona charger that can be prevented.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that (i) zeolite is effective for removing discharge products by corona discharge, and (ii) the grid electrode portion among the members in the corona charger. (Iii) When holding the zeolite in the grid, it is necessary to have a predetermined electrode resistance to ensure the function as a charge control electrode. We have researched on a charger with a coating layer containing zeolite in the grid part. The present inventor has further intensively studied and formed a coat layer on the inner side of the end face of the grid, so that the interval between the photoconductor and the grid can be stabilized and the uniformity of charging can be improved. Heading, reaching the present invention.

That is, according to the present invention, the following scorotron type corona charger, process cartridge and image forming apparatus are provided.
(1) In a scorotron type corona charger having a grid on which a coat layer containing at least zeolite, a resistance control agent and a binder resin is formed, the coat layer is formed on the inner side of the end face of the grid. A scorotron type corona charger characterized by being.
(2) The scorotron corona charger according to (1), wherein the coat layer is a coat layer formed by a screen printing method.
(3) A process cartridge comprising a combination of the scorotron type corona charger according to (1) or (2) and at least an electrophotographic photosensitive member.
(4) An image forming apparatus using the scorotron type corona charger described in (1) or (2) or the process cartridge described in (3).

A scorotron-type corona charger having a charging grid, wherein the grid electrode is a scorotron-type corona charger in which a coating layer containing at least zeolite, a resistance control agent, and a binder resin is formed. By being formed on the inner side of the end face, it is easy to attach to the charger, and the amount of gas and discharge products generated from the charger is reduced efficiently and continuously, and contamination and alteration of the charged object such as a photoreceptor. By suppressing the image, a stable image can be maintained.
In addition, the grid casing of a scorotron type corona charger usually has a structure in which guide rails are cut in the longitudinal direction, and if the grid is mounted along the guide rails, the end film will rise and become uneven. If the grid is slightly deformed and the gap with the drum is not uniform, by providing a portion without a coating layer as in the present invention, the portion without the coating layer becomes an accurate metal surface. Therefore, there is no deformation of the grid as described above, and the gap can be made uniform.

<Corona charger>
The scorotron charger according to the present invention has the configuration shown in FIG. 1B, and includes at least a shield case, a charging wire, and a grid electrode as essential components. FIG. 4 shows a charging method of the scorotron type corona charger. In FIG. 4, the charger and the photoconductor are installed facing each other, Vc: −5 to −8 kV is applied to the charging wire, Vg: −500 to −1500 volt is applied to the grid electrode, and the photoconductor is charged near Vg. It is intended for uniform charging. As described above, in the corona charging, discharge products such as O ₃ , NOx, ammonium ions, and nitrate ions are generated by high-pressure discharge, and they are accumulated in the charger (in the shield case). The main object of the present invention is to reduce the discharge products accumulated in the shield case and to reduce discharge products generated at the time of discharge as needed. We are trying to reduce things. As a result of various examinations, it has been found that the holding position of the zeolite can suppress deterioration of the surface of the photoreceptor due to the discharge product and abnormal images due to the holding of the grid electrode. As described above, since the grid electrode is a control electrode for making the charging potential of the photosensitive member uniform by corona discharge, it is necessary to discharge from the charging wire to the grid electrode, and the surface resistance of the grid electrode is 1. × 10E10 Ωcm or less is required. Therefore, the grid electrode according to the present invention has a configuration in which zeolite and a resistance control agent are held on a conductive mesh-shaped or wire-shaped metal grid.

<Zeolite>
Next, the zeolite according to the present invention will be described. Zeolite is a general term for crystalline porous aluminosilicate, composition formula _{^{(M n +) 2 / n}} O · Al 2 O 3 · xSiO 2 · yH 2 O
n: valence of cation M
x: Number of 2 or more
y: a substance represented by a number of 0 or more.

In the skeletal structure, aluminum (+3 valence) and silicon (+4 valence) share oxygen (-2 valence) with each other, so that silicon is electrically neutral and aluminum is −1. In order to compensate for this negative charge, a cation (eg, Na ⁺ ) is required in the skeleton. This cation can be easily exchanged with other metal ions (for example, H ⁺ , K ⁺ , Ca ^2+, etc.), and the zeolite can have various functions depending on the kind of the cation. In addition, the framework of zeolite is formed by three-dimensionally combining Si—O—Al—O—Si structures, and there are various regular forms of frameworks by this three-dimensional combination. Further, the skeleton has uniform pores derived from a skeleton made of silicon, aluminum, and oxygen, and water, various gases, and organic molecules can be selectively taken into the skeleton.

Zeolite differs in the molecules that can be adsorbed because the pore size changes depending on the crystal form and the type of cation. Therefore, effective removal is possible by selecting the crystal form and cation species. 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.
In addition to natural zeolite, there are artificial zeolites obtained by treating industrially produced wastes such as synthetic zeolite and coal ash.

  The type of the zeolite used in the present invention is not particularly limited, but the crystal type is A type or X type, high valence ions such as iron, aluminum, calcium and magnesium in the cationic species, and potassium in the monovalent type. Ions with large atomization are suitable for the adsorption, ion exchange, and decomposition of the discharge product that is the object of the present invention.

<Resistance control agent>
In order to hold the zeolite on the grid electrode, the zeolite can be held on the grid by dispersing the zeolite in a binder resin and applying it to the charged grid. Usually, the charging grid is conductive, but if it is covered with a binder resin and zeolite, the electric resistance increases, and the function of controlling the surface potential cannot be performed. Therefore, it is necessary to mix a resistance control agent for the purpose of imparting conductivity to the resin film of zeolite / binder resin. As the resistance control agent, conductive metal oxide fine particles such as indium oxide, zinc oxide and tin oxide, conductive activated carbon particles, and the like can be used. In some cases, two types of resistance control agents may be used.

<Binder resin>
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, polychlorinated resin. Vinyl, 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 And thermoplastic or thermosetting resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, etc. From the viewpoint of durability of the coating layer, it is a curable binder Resin preferred There.

<Formation of charging grid>
In order to form a charged grid according to the present invention, a coating film forming liquid comprising at least zeolite, a binder resin, a resistance control agent, and a solvent may be applied to and dried on a grid electrode that has been conventionally used. That is, as the grid serving as the substrate, a wire or mesh shape made of a material such as stainless steel or tungsten can be used, and an etching grid etched in a mesh shape with an interval of 0.5 to 3 mm is particularly preferable. What is necessary is just to apply | coat the above-mentioned coating-film formation liquid with respect to this base-material grid electrode by methods, such as spray application | coating, immersion application | coating, and screen printing, and to heat-dry as needed. Since zeolite and the resistance control agent are in the form of particles, various conventional dispersion methods such as a ball mill, a vibration mill, an ultrasonic wave, and a sand mill can be used for preparing the coating film forming liquid.

As the solvent for the coating film forming solution, a ketone solvent such as cyclohexanone and methyl ethyl ketone, an ester solvent such as tetrahydrofuran, and an alcohol solvent such as methanol and butanol can be used according to the binder resin. A solvent can be used individually or in mixture of 2 or more types.
The solid content concentration of the coating film-forming solution can be arbitrarily selected, but it is preferable to appropriately adjust the coating method and the fixing resin. For example, in the case of screen printing coating, it is necessary to examine the ratio of the selected binder resin to the solvent so that the viscosity of the forming liquid is 500 to 5000 mPa · s.

The blending ratio of zeolite / resistance control agent / binder resin is preferably 30-50 parts for zeolite, 10-30 parts for resistance controller, and 10-30 parts for binder resin.
The thickness of the layer composed of zeolite, resistance control agent, and binder resin is preferably 5 to 100 μm, and if it is less than 5 μm, the sustainability of the discharge product absorption and decomposition ability is insufficient, and if it is 100 μm or more, it functions as a grid. It becomes difficult to control a certain charging potential, and the photosensitive member cannot be charged to a constant charging potential.

  The coating liquid can be prepared by preparing the binder resin in a ratio of about 5 to 10 wt% with respect to the solvent and adding zeolite particles and a resistance control agent while stirring. In the case of spray coating, the coating liquid can be prepared by adding the binder resin to the solvent at a ratio of about 5 to 10 wt% and adding zeolite particles and a resistance control agent while stirring. it can. The coating liquid solid content concentration is 30 wt% or less.

As a method for applying the coating layer to the charging grid, there are a dipping method, a roller coating method, a spray method, and the like, and a screen printing method is particularly suitable for the present invention.
The reason why the screen printing method is particularly suitable is that it is easy to form the end portion of the coat layer inside the end surface of the grid. The coating layer may be applied by spraying or the like, but in this case, the coating layer is formed on the entire surface of the grid. It is necessary to polish and peel off.

  Since the coating layer is formed on the discharge surface of the charging grid, the discharge product can be efficiently removed. When a coat layer is formed on one side of the grid by a spray coating method or a screen printing method and is attached to the casing, the coat layer surface may be attached to the discharge wire side. It is possible to form the coating layer only on one side by spray coating or screen printing. In the spray coating method, a coat layer is formed slightly from the side surface to the back surface side. In screen printing, if the coating liquid wraps around the back surface, it will hinder the next printing. Therefore, it is necessary to suppress the wrapping around the back surface as much as possible from the relationship between the viscosity of the coating layer forming liquid and the printing mesh.

The grid casing that holds the grid is provided with grid guide rails, and in order to make the distance between the grid and the drum uniform, it is necessary to remove the paint swell on the end face. As the width, a removal width of 1 mm or more is necessary. In addition, if the removal width exceeds 5 mm, the effect of absorbing the discharge product is reduced, so that the removal width is preferably 1 to 5 mm.
In addition, the grid casing has a structure in which guide rails are cut in the longitudinal direction, and if the grid is mounted along the guide rails, the end film is unevenly raised, so the grid is slightly deformed and the drum And the gap will not be uniform. Since the portion without the coating layer is a highly accurate metal surface, there is no deformation of the grid and the gap can be made uniform.

[Electrophotographic photoconductor]
In the image forming apparatus of the present invention, a conventionally known electrophotographic photosensitive member can be used.
The electrophotographic photosensitive member will be described with reference to the drawings.
FIG. 5 is a cross-sectional view showing an example of the electrophotographic photosensitive member used in the present invention. On the conductive support (31), an intermediate layer (33), a charge generation layer (35) having a charge generation function, This is a photoreceptor having a laminated structure in which a charge transport layer (37) having a charge transport material function is laminated.

<Conductive support>
Examples of the conductive support (31) include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals 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 Publication No. 52-36016 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) used in 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-vinyl carbazole, 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 (31) of the present invention.

<Intermediate layer>
The structure of the intermediate layer (33) that can be provided for the purpose of preventing charge injection from the conductive support (31) to the photosensitive layer or for preventing interference fringes is that the binder resin or particles are contained in the binder resin. The binder resin may be a thermoplastic resin such as polyvinyl alcohol, nitrocellulose, polyamide, or polyvinyl chloride, or a thermosetting resin such as polyurethane or alkyd-melamine resin. As particles to be dispersed in the intermediate layer, titanium oxide, aluminum oxide, tin oxide, zinc oxide, zirconium oxide, magnesium oxide, silica and their surface treatment products are used, and titanium oxide is more preferable in terms of dispersibility and electrical characteristics. Both rutile and anatase types can be used.
In order to form the intermediate layer, for example, the above-described binder resin may be dissolved in an organic solvent, and the above-described particles may be dispersed in the solution by means of a ball mill, a sand mill, or the like, and applied to a support and dried. . The thickness of the intermediate layer is 10 μm or less, preferably 0.1 to 6 μm.

<Photosensitive layer>
(Charge generation layer)
The charge generation layer (35) 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 a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having 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 (35) 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, 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 (35) may contain a low molecular charge transport material.
Low molecular charge transport materials that can be used in combination with the charge generation layer (35) include hole transport materials and electron transport materials.
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.

As a method of forming the charge generation layer (35), a vacuum thin film preparation method and a casting method from a solution dispersion system are mainly exemplified.
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 (37) 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 (35) 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 (35) 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 (37) can be formed by the same coating method as the charge generation layer (35).

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.

  FIG. 3 is a schematic view of an example of the image forming apparatus of the present invention. 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 means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable.
A process cartridge for an image forming apparatus according to the present invention includes at least an electrophotographic photosensitive member and a scorotron type corona charger according to the present invention, and includes a developing device, a transfer unit, a cleaning unit, a discharging unit and the like as an integrated unit. The apparatus (component) is detachable from the image forming apparatus main body.

The scorotron charger according to the present invention is used in a process cartridge that integrally supports at least one unit selected from a photosensitive member, a developing unit, and a cleaning unit and is detachable from an image forming apparatus main body. it can.
FIG. 8 shows a schematic configuration of an image forming apparatus provided with a process cartridge having a scorotron charger of the present invention.
In the figure, reference numeral 1 denotes the entire process cartridge, 2 denotes a photosensitive member, 3 denotes a charger, 4 denotes developing means, and 5 denotes cleaning means.
In the present invention, a plurality of constituent elements such as the above-described photoreceptor 2, charger 3, developing means 4, and cleaning means 5 are integrally combined as a process cartridge, and this process is performed. The cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

The operation of the image forming apparatus provided with the process cartridge having the electrostatic latent image developing developer of the present invention will be described as follows.
The photoreceptor is driven to rotate at a predetermined peripheral speed. In the rotation process, the photosensitive member is charged uniformly with positive or negative predetermined potential on its peripheral surface by a charger, and then receives image exposure light from image exposure means such as slit exposure or laser beam scanning exposure. An electrostatic latent image is sequentially formed on the peripheral surface of the photosensitive member, and the formed electrostatic latent image is then toner developed by a developing unit, and the developed toner image is transferred from the sheet feeding unit to the photosensitive member and the transfer unit. Then, the image is sequentially transferred by the transfer means to the transfer material fed in synchronization with the rotation of the photosensitive member. The transfer material that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means, and fixed on the image, and printed out as a copy (copy). The surface of the photoconductor after the image transfer is cleaned by removing the transfer residual toner by a cleaning means, and after being further neutralized, it is repeatedly used for image formation.

  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.

<Photoconductor Preparation Example 1>
By coating and drying an intermediate layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution of the following composition on a φ100 mm aluminum cylinder in order, a 3.5 μm intermediate layer, A 2 μm charge generation layer and a 32 μm charge transport layer were formed to obtain photoreceptor 1.
[Coating liquid for intermediate 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 (KR5240, 15% xylene-butanol solution: manufactured by Shin-Etsu Chemical Co., Ltd.) 70 parts 2-butanone 200 parts

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

Example 1
A coating solution for the coating layer of the grid was prepared using the materials shown below. The weight ratio of zeolite / resistance control agent / binder resin was 5/3/2. The solid content concentration of the liquid was adjusted to 50 wt%.
Catalyst ・ ・ ・ Zeolite (Type A zeolite A-3 powder type Tosoh product)
Resistance control agent ・ ・ ・ SnO ₂
Binder resin ・ ・ ・ Polyvinyl butyral Dispersion medium ・ ・ ・ Cyclohexanone / Methyl ethyl ketone = 7/3
The above mixed solution is dispersed with a ball mill for 24 hours to obtain a coating solution. After coating the coating solution on a stainless steel etching grid by spraying, the coating layer is polished and peeled to 1 mm inside from the grid end face. A grid having a coating layer as shown in FIG. 6 formed inside the end face of the grid was obtained.

The obtained grid was mounted along a guide on a charger in which a guide groove was cut in the charger casing to obtain a charger as shown in FIG. A scorotron type corona charger having a grid coated with a coating layer containing zeolite, a resistance control agent and a binder resin was obtained. The coating film thickness was 50 μm.
The groove depth was 1 mm, and the curvature of the grid was the same as that of the photoconductor of φ100 mm.

Subsequently, the following evaluation was performed.
(Evaluation of charge control)
The corona charger obtained in Example 1 was attached to an imagio Neo 1050pro having a process cartridge. Thereafter, a halftone image was output, and the uniformity of the halftone image was evaluated by an image density difference.
The grid voltage applied to the grid electrode was 900 volt, and the wire current was 1100 mA.
For the evaluation, the photoreceptor shown in Preparation Example 1 was used.

(Example 2)
Example except that the coating method was changed from the spray coating method to the screen printing method (using 200 mesh), the screen size was 1 mm smaller than the grid size, and the inner side of the grid was coated 1 mm inside. In the same manner as in Example 1, a scorotron type corona charger was obtained.
Next, the corona charger was evaluated in the same manner as in Example 1.

(Example 3)
A scorotron-type corona charger was obtained in the same manner as in Example 2 except that the binder resin was changed to a urethane-crosslinked acrylic resin, and the corona charger was evaluated in the same manner as in Example 2.

(Comparative Example 1)
A scorotron-type corona charger was obtained in the same manner as in Example 1 except that the coating layer was spray-coated and 1 mm from the end face was not polished or peeled off.

ゼオライトを含む形成液を塗布した帯電グリッドを用いることによりＮＯxの発生量が削減され、帯電器内での放電生成物の除去効果のあることはこれまでの我々の検討と出願で明らかになっている。この改良型スコロトロン帯電器において、本発明に従えば、グリッドと感光体のギャップを均一性を高めることが出来る為、帯電の均一性、ひいては画像の均一性を高めることが出来る。

It has been clarified in our examination and applications so far that the generation amount of NOx is reduced by using a charging grid coated with a forming liquid containing zeolite, and the discharge product is removed in the charger. Yes. In this improved scorotron charger, according to the present invention, the gap between the grid and the photoconductor can be increased in uniformity, so that the charging uniformity and thus the image uniformity can be improved.

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 charging method of a scorotron type corona charger. It is sectional drawing which shows an example of the layer structure of the electrophotographic photoreceptor used for this invention. It is the side view and top view which show the grid produced in the Example. It is drawing which shows the charging device equipped with the grid produced in the Example. It is the schematic which shows the structure of the process cartridge of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Process cartridge 2 Photoconductor 3 Charging means 4 Developing means 5 Cleaning means 31 Conductive support 33 Intermediate layer 35 Charge generation layer 37 Charge transport layer 100 Photoconductor 101 Charging device 102 Image exposure system 103 Developing device 104 Transfer device 105 Cleaning device 106 Cleaning brush 107 Elastic rubber cleaning blade 108 Static neutralizer 109 Copy paper

Claims (4)

  In a scorotron type corona charger having a grid on which a coating layer containing at least zeolite, a resistance control agent and a binder resin is formed, the coating layer has a shape formed inside the end face of the grid. Scorotron type corona charger.   The scorotron type corona charger according to claim 1, wherein the coat layer is a coat layer formed by a screen printing method.   3. A process cartridge comprising a combination of the scorotron type corona charger according to claim 1 and at least an electrophotographic photosensitive member.   An image forming apparatus using the scorotron type corona charger according to claim 1 or the process cartridge according to claim 3.

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