JP2013101286A - Photoreceptor protective agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormal image derived from a discharge product occurring in a charger using discharge in an electrophotographic device.SOLUTION: A photoreceptor protective agent 105 comprising metal salt of fatty acid and rhodium-containing metal oxide is supplied to a photoreceptor 100, a photoreceptor protective layer is formed on the photoreceptor surface, and a discharge product occurring in a charger is decomposed and removed by the catalytic action of rhodium.

Description

  The present invention relates to a protective agent for a photoreceptor surface used in an image forming process by an electrophotographic method, an apparatus for forming a layer of the protective agent on the photoreceptor surface, and an image forming apparatus and a process cartridge provided with the apparatus.

In general, image formation in an electrophotographic apparatus is performed by irradiating a uniformly charged photosensitive member with writing light modulated by image data to form an electrostatic latent image on the photosensitive member. Toner is supplied to the photoconductor on which the toner is formed by a developing unit to form a toner image on the photoconductor and develop it. 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. This is a series of image forming processes in which the toner is recovered by a method such as scraping with a cleaning blade in the cleaning unit.

As means for charging the photoreceptor, which is the first stage of the image forming process, it is known that a device using wire-shaped corona discharge, a roller, a device using brush-shaped proximity discharge, and the like can be used.
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.
The corona generator most relevant to the present invention and its problems will be described below.

(1) Corotron type corona generator
An outline of the configuration of the corotron type corona generator is shown on the left of FIG. 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. With the opening surface facing the charged body (photoconductor), 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 charged body surface for charging. To do. As shown in the left of FIG. 2, the corotron corona generator generates a certain amount of charge, and is not necessarily good at uniformly charging a charged object surface having a film thickness deviation to a constant potential, for example.

(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 on the right side of FIG. 1, 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 on the right side of 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 it is a corotron type or a scorotron type, 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 discharge products such as NOx, 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.

For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2005-227470), a conductive paint containing graphite particles, nickel particles, aluminum compound particles and an organic resin binder is applied to a SUS material charging grid of a corona generator. The corrosion by the discharge product of the control electrode is suppressed, and the generated discharge product is absorbed by the conductive film, thereby suppressing the contamination of the charged body. This means uses the action of the fine particles in the film absorbing the discharge products, but the amount that can be absorbed is determined by the number of adsorption sites of the particles, so the adsorption sites are buried when used over time. It is expected that the effect will fade quickly.

  In Japanese Utility Model Publication No. 62-089660, ozone is prevented from diffusing by providing an opening in a corona generator and forming an ozone-adsorbing particle layer in a finely divided communicating opening. In addition, zeolite and activated carbon are used as ozone adsorption particles (Patent Document 2). 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.

In Patent Document 3 (Japanese Patent Laid-Open No. 2003-43894), in addition to the product removing means for adsorbing the discharge product adhering to the surface of the member to be charged, the product adhesion preventing the discharge product from adhering to the surface of the member to be charged is difficult. Means, a resistance reduction preventing means for preventing the discharge product attached to the surface of the charged body from decreasing, and a product generation preventing means for reducing the amount of discharge product generated in the vicinity of the surface of the charged body There is an example in which an adsorbent such as zeolite is disposed between the charged body and the corona generator, but another discharge product adsorbing means is covered. It is indispensable to make contact with the charged body, 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.

In Patent Document 4 (Japanese Patent Laid-Open No. 2007-121460), a grid wire coated with at least one of gold, platinum, iridium, rhodium, ruthenium, and palladium as an adsorption inhibitor for discharge products and foreign matter attached to the wire are statically removed. Disclosed is a charging means provided with a cleaning means that is electrically removed. Although an embodiment of gold plating is disclosed, there is no disclosure of an embodiment of rhodium, and its action and effect are not clear.

Patent Document 5 (Japanese Patent Laid-Open No. 2010-210802) discloses a method for improving the stability of image quality by improving the ozone resistance and NOx resistance of a photoreceptor by incorporating a specific amine compound in the photosensitive layer. Patent Document 6 (Japanese Patent Laid-Open No. 2010-079130) discloses a method in which a substance such as a crown ether that captures discharge product ions is included in the outermost surface layer of the photoreceptor. However, when these materials are included in the photosensitive layer, the charging characteristics and light attenuation characteristics of the photosensitive member are changed, and as a result, maintaining high image quality for a long period of time is a problem.
As described above, a method for removing and reducing products, particularly NOx, generated by the discharge of the charger of the image forming apparatus has not yet been completed.

  The present invention has been studied in view of the above circumstances, and is the amount of discharge products generated from a charger utilizing high-pressure discharge in the atmosphere, in particular, NOx affects the photosensitive member, An object is to prevent the occurrence of abnormal images such as density unevenness and a decrease in resolution, and to further improve the sustainability of the prevention effect as compared with the prior art.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that (1) rhodium is effective in removing discharge products, particularly NOx, by corona discharge, and (2) the NOx removal effect by rhodium is sustainable. It is known that the reason is the catalytic effect of rhodium. (3) Usually, the catalytic effect of rhodium is known to exert its effect to the maximum when the temperature is increased to several hundreds of degrees Celsius and the concentration is high. It can exhibit its catalytic effect even at low temperatures and at high temperatures under high-pressure discharge energy. (4) Any oxide of CeO2, Al2O3, ZrO2 is effective as a rhodium holding member. (5) Rhodium In addition to the above, it has been found that the sustainability of the effect is dramatically improved by holding any one of platinum, palladium, and lanthanum together, and the present invention has been achieved. The means of the present invention for solving the problem are as follows.

(1) A photoconductor protective agent used in an image forming process having a step of applying or adhering a protective agent to the surface of an electrophotographic photosensitive member, wherein the photoconductor protective agent contains a metal salt of a fatty acid and a metal oxide. The metal oxide contains rhodium. Photoconductor protective agent.
(2) The photoconductor protective agent as described in (1) above, wherein the metal oxide comprises one or more metal oxides and contains at least one of CeO2, Al2O3 and ZrO2.
(3) In addition to rhodium contained in the metal oxide, it contains a metal oxide containing at least one of platinum, palladium, and lanthanum. The photosensitivity as described in (1) or (2) above Body protectant.
(4) The photoconductor protective agent according to any one of (1) to (3) above, which is solidified by compression molding.
(5) A photosensitive member protective layer forming apparatus for applying or adhering a photosensitive member protective agent to the surface of an electrophotographic photosensitive member, wherein the photosensitive member protective agent is any one of the above (1) to (4). A photosensitive member protective layer forming apparatus, which is a photosensitive member protective agent.
(6) The photosensitive member protective layer forming apparatus according to (5), wherein the photosensitive member protective agent is supplied to the surface of the photosensitive member through a supply member.
(7) An image forming apparatus comprising the photosensitive member protective layer forming apparatus according to (5) or (6).
(8) A process cartridge comprising the photosensitive member protective layer forming apparatus according to (5) or (6).

The photoconductor protective agent of the present invention is a lubricant containing fatty acid metal salt containing a rhodium-containing metal oxide. By applying or adhering to the surface of the electrophotographic photoconductor, for example, a corona charger or the like is used. Discharge products discharged from chargers using voltage, especially NOx gas, are decomposed efficiently and continuously by the catalytic action of rhodium to prevent abnormal images due to contamination and alteration of the photoconductor and adhesion of discharge products. I can do it. In particular, the layer of the photoconductor protective agent formed on the surface of the photoconductor is removed by the cleaning mechanism together with other components such as toner remaining on the photoconductor by a normal cleaning mechanism. It is removed and the constant catalytic action is always continued, and the adverse effects caused by the discharge products can be eliminated stably.

The figure which shows the outline | summary of a structure of a corotron type | mold corona generator and a scotron type | mold corona generator. The figure which shows the charging characteristic of a corotron type | mold corona generator, a scotron type | mold, and a corona generator. 1 is a schematic diagram showing an outline of an image forming apparatus. 1 is a schematic configuration diagram of a photoreceptor protective layer forming apparatus of the present invention. FIG. 3 is a diagram showing the configuration of the apparatus when the photosensitive member protective layer forming apparatus of the present invention is provided upstream of the cleaning mechanism. FIG. 3 is a diagram illustrating a layer structure of a photoreceptor used in the present invention.

First, the image forming process of the image forming apparatus on which the photoconductor protective agent according to the present invention is mounted will be described with reference to FIG. The outline of this image formation process is as follows.
1) The charging device 101 charges (±) 600 to 1400 V to the image carrier (photosensitive member) 100. Examples of the charging device include a corotron type or scotron type corona charger.
2) 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.

3) The photoconductor 100 on which the latent image is formed according to the original is developed with a developer by the developing device 103, and the original image is visualized (toner image).
4) Next, the toner image on the photosensitive member is transferred to the copy sheet 109 by applying a voltage to the transfer device 104.
Some voltages applied in the transfer are controlled by constant current so that the current flowing through the photosensitive member is constant.

  5) On the other hand, after the photosensitive member 100 is transferred, the photosensitive member protective agent 105, the photosensitive member protective agent supply member 106, and the protective layer forming mechanism 107 apply the photosensitive member protective agent to the photosensitive member, and then the toner image is cleaned and cleaned. Is done. As the photosensitive member protective layer supply member 106 and the protective layer forming mechanism 107, a cleaning brush and an elastic cleaning blade that are usually used as a cleaning unit for the photosensitive member can be used.

  6) Since the latent image (original image) after the toner image is formed is held on the photoconductor after cleaning to some extent, a static eliminator (generally, red light is used to erase and make uniform) ) 108, 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 machine, a facsimile machine, or a printer. However, the photoconductor protective layer forming apparatus of the present invention may be used together with a photoconductor, or further, a charging device, a developing device, a transfer device, or the like. By combining one or more of the cleaning devices or the like, the process cartridge may be detachably incorporated in the image forming apparatus main body.

<Protective layer forming apparatus>
The protective layer forming apparatus of the present invention will be described below with reference to FIG.
A protective layer forming device disposed opposite to a photosensitive drum as an image carrier is composed of a photosensitive member protective agent (hereinafter also simply referred to as “protective agent”) 105 formed in a block shape (columnar shape), a supply member. A protective agent supply member 106, a pressing force applying mechanism 110, a protective layer forming mechanism 107 as a layer forming member (layer forming means), and the like.
Here, a coil spring is illustrated as an urging means for the pressing force applying mechanism 110 and the protective layer forming mechanism 107, but the present invention is not limited to this. For example, a member having rubber elasticity, a leaf spring, and other elastic members are used. But you can.

The photoconductor protective agent 105 contacts the rotating brush-like protective agent supply member 106 by the pressing force from the pressing force applying mechanism 110.
The protective agent supply member 106 rotates and rubs with the photosensitive member 100 with a linear velocity difference. At this time, the toner on the surface of the photosensitive member is cleaned, and at the same time, the photosensitive member held on the surface of the protective agent supply member 106. A protective agent is supplied to the surface of the photoreceptor.
The photoconductor protective agent supplied to the surface of the photoconductor is thinned (formed into a film) by the protective layer forming mechanism 107.

The deteriorated photoconductor protective agent is removed by the cleaning mechanism together with other components such as toner remaining on the photoconductor by a normal cleaning mechanism.
FIG. 5 shows a case where a protective agent forming device is provided upstream of the cleaning mechanism.
In this case, the cleaning mechanism 111 supplies the photosensitive member protective agent held on the surface of the protective agent supply member 106 to the photosensitive member surface with almost no toner on the photosensitive member surface. In this case, since the contamination of the protective layer supply member 106 with toner or the like is reduced, the protective agent can be supplied to the image carrier more uniformly.

The photoconductor protective agent of the present invention includes a fatty acid metal salt, a metal oxide, and a metal oxide containing rhodium.

As fatty acid metal salts, typical stable metal salts of fatty acids include barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, stearin. Cadmium acid, magnesium stearate, zinc stearate, zinc oleate, magnesium oleate, iron oleate, cobalt oleate, copper oleate, lead oleate, manganese oleate, zinc palmitate, cobalt palmitate, lead palmitate , Magnesium palmitate, aluminum palmitate, calcium palmitate, lead caprylate, lead caprate, zinc linolenate, cobalt linolenate, calcium linolenate, zinc ricinoleate, potassium ricinoleate Miumu and mixtures thereof, but not limited to this, it is possible to use a fatty acid metal salt generally used as a lubricant in an image forming apparatus.

As a raw material of rhodium, a compound containing rhodium can be used, and is not particularly limited. However, rhodium nitrate, rhodium chloride, rhodium acetate, hexaammine rhodium and the like are preferable.

As the metal oxide, for example, at least one of CeO2, Al2O3, and ZrO2 is used.
In the present invention, for example, one or more of these metal oxides in powder form are impregnated with an aqueous solution of the above rhodium compound, dried and fired to obtain a metal oxide powder containing rhodium. Rhodium is supported on metal oxide particles in the form of metal fine particles. Hereinafter, this rhodium-containing metal oxide powder may be referred to as rhodium powder.
In the present invention, a metal oxide powder containing one or more of noble metals such as platinum, palladium and lanthanum can be separately prepared and used in combination with the rhodium powder. The method for producing these noble metal-containing metal oxide powders is basically the same as the method for producing the rhodium powder. In addition, hereinafter, these noble metal-containing oxide powders may also be referred to as platinum powder and palladium powder.

When these noble metal-containing metal oxide powders and the rhodium powder are used in combination, the catalytic effect on product decomposition by high voltage discharge is maximized.
The ratio of rhodium and metal oxide is preferably maintained in the range of 0.1 to 10 wt% in the metal oxide from the viewpoint of the effect and the sustainability of the NOx gas catalyst.

On the other hand, the ratio of the metal oxide to the fatty acid metal salt in the photoconductor protective agent is preferably included in the range of 5 to 20 wt% from the viewpoint of accumulation on the photoconductor.
Further, the photoconductor protective agent can be molded by melting or compression.
In the case of melt molding, it is produced by cast molding in which a metal mold is filled with a fatty acid metal salt and rhodium. It is manufactured by cast molding in which a molten fatty acid metal salt is filled in a mold. For this reason, cost increases due to melting and consideration for the environment are problems. In the case of compression molding, the solidified lubricant molded product can reduce manufacturing cost and manufacturing energy. In the case of compression molding, the amount of application to the image carrier is easier to adjust when it is supplied via a brush roller because the compression molding does not become too hard and the hardness is appropriate.

<Photoconductor>
In the photoreceptor used in the present invention, conventionally known materials and forming methods can be used for the configuration other than the outermost layer. The photoreceptor will be described below with reference to FIG.
FIG. 6 is a cross-sectional view of a photoreceptor, and the photoreceptor used in the present invention is a photoreceptor having a laminated structure in which an undercoat layer, a charge generation layer, a charge transport layer, and a surface layer are sequentially laminated on a conductive support. is there.

<Surface layer>
Typical examples of the surface layer include those obtained by dispersing inorganic fine particles in a binder resin and those obtained by polymerizing a crosslinkable charge transport material and a resin. Examples of this resin are preferably phenol resin, urethane resin, melamine resin, curable acrylic resin, siloxane resin, and the like.
Furthermore, in order to improve the electrical characteristics of the protective layer, a charge transport material for a charge transport layer described later can be contained.
The film thickness of the surface layer is preferably in the range of 0.5 to 10 μm from the viewpoint of photoreceptor characteristics and printing durability.

<Conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. After metal oxide is deposited or sputtered, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes that have been subjected to surface treatment such as cutting, super-finishing, and polishing can be used.

Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-58-86547 can also be used as the conductive support.
In addition, those obtained by dispersing and coating conductive powder in an appropriate binder resin on the support can also be used as the conductive support 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-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 of the present invention.

<Underlayer>
The structure of the undercoat layer that can be provided for the purpose of preventing charge injection from the conductive support to the photosensitive layer and for the purpose of preventing interference fringes is that the binder resin or particles are dispersed in the binder resin. As the binder resin, thermoplastic resins such as polyvinyl alcohol, nitrocellulose, polyamide, and polyvinyl chloride, and thermosetting resins such as polyurethane and alkyd-melamine resin can be used.
As the particles to be dispersed in the undercoat layer, titanium oxide, aluminum oxide, tin oxide, zinc oxide, zirconium oxide, magnesium oxide, silica and their surface-treated products are used, and titanium oxide is more preferable in terms of dispersibility and electrical characteristics. Any of the rutile and anatase types can be used.

In order to form the undercoat layer, for example, the above-described binder resin is dissolved in an organic solvent, and the above-described particles are dispersed in the solution by means of a ball mill, a sand mill, or the like, and applied to a support and dried. good.
The thickness of the undercoat layer is 10 μm or less, preferably 0.1 to 6 μm.

<Photosensitive layer>
As the photosensitive layer, there are a laminated type photosensitive layer in which the function is separated into a charge generation layer and a charge transport layer, and a single layer type photosensitive layer in which they are combined. Hereinafter, a laminated photosensitive layer will be described as a representative example.

(Charge generation layer)
The charge generation layer 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, examples of the organic material include 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, and diphenylamine skeletons. Azo pigments having a 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 distyryloxadiazole skeleton, distyryl Azo pigment having carbazole skeleton, perylene pigment, anthraquinone or polycyclic quinone pigment, quinone imine pigment, diphenylmethane and triphenylmethane pigment, benzoquinone and naphthoquinone pigment, cyanine Fine azomethine pigments, indigoid pigments, and bisbenzimidazole pigments.
These charge generation materials can be used alone or as a mixture of two or more.

The binder resin used as necessary for the charge generation layer includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, Examples include 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.
In addition, the charge generation layer may contain a low molecular charge transport material described later.

Methods for forming the charge generation layer mainly include 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 a charge generation layer by the casting method described later, if necessary, the inorganic or organic charge generation material, together with a binder resin, 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 is a layer having a charge transport function, and is formed by dissolving or dispersing a charge transport material having a charge transport function and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer.
Low molecular charge transport materials that can be used for the charge transport layer 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 the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer 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 can be formed by the same coating method as that for the charge generation layer.
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, a plasticizer of a resin such as dibutyl phthalate or dioctyl phthalate can be used, and the amount used is suitably about 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin. .

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 60 μm, preferably about 10 to 40 μm.
In the image forming apparatus according to the present invention, conventionally known constituent members other than the photoreceptor can be used.

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.

<Photoreceptor: Formation to undercoat layer, charge generation layer, charge transport layer>
[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-82-60, manufactured by Dainippon Ink & Chemicals) 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: manufactured by 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)
Tetrahydrofuran 200 parts

<Adjustment of rhodium powder for image carrier protecting agent>
(Adjustment of rhodium powder A)
Ceria-containing zirconia powder (containing 10 wt% of CeO 2) was impregnated in an aqueous rhodium nitrate solution, dried at 120 ° C. for 2 hours, and calcined at 400 ° C. for 1 hour. Next, this powder was mixed with water and pulverized using a bead mill to obtain a slurry solution.
Further, boehmite was added to this slurry solution, and after sufficient mixing and stirring, dried at 370 ° C. and calcined at 550 ° C. for 3 hours to obtain rhodium powder A.
The obtained rhodium powder for Examples was a powder having an average particle diameter of 0.3 μm composed of rhodium 1 wt% -ceria 5 wt% -zirconia 44 wt% -alumina 50 wt%.

(Adjustment of rhodium powder B)
Gamma alumina was impregnated with an aqueous zirconyl nitrate solution, dried at 150 ° C., and then fired at 400 ° C. for 1 hour to obtain zirconia-containing alumina powder (containing 3 wt% of ZrO 2).
This powder was impregnated with an aqueous rhodium nitrate solution, dried at 120 ° C. for 2 hours, and then fired at 400 ° C. for 1 hour to obtain rhodium powder B.
The obtained rhodium powder for comparative example was a powder having an average particle diameter of 0.4 μm composed of rhodium 1 wt% -zirconia 3 wt% -alumina 96 wt%.

(Palladium powder adjustment)
A cerium nitrate aqueous solution was impregnated with γ-alumina, dried at 150 ° C., and then fired at 400 ° C. for 1 hour to obtain a ceria-containing alumina powder (containing 3 wt% of CeO 2).
This powder was impregnated with an aqueous palladium nitrate solution, dried at 120 ° C. for 2 hours, and then fired at 400 ° C. for 1 hour to obtain a palladium powder.
The obtained palladium powder for comparative example was a powder having an average particle diameter of 0.4 μm composed of palladium 5 wt% -ceria 3 wt% -alumina 92 wt%.

(Platinum powder adjustment)
A cerium nitrate aqueous solution was impregnated with γ-alumina, dried at 150 ° C., and then fired at 400 ° C. for 1 hour to obtain a ceria-containing alumina powder (containing 3 wt% of CeO 2).
This powder was impregnated and supported in a dinitrodiamine platinum aqueous solution, dried at 120 ° C. for 2 hours, and then fired at 400 ° C. for 1 hour to obtain a platinum powder for comparison.
The obtained platinum powder for comparative example was a powder having an average particle diameter of 0.4 μm composed of platinum 1 wt% -ceria 3 wt% -alumina 96 wt%.

(Preparation of alumina powder not containing catalyst)
A cerium nitrate aqueous solution was impregnated with γ-alumina, dried at 150 ° C., and then fired at 400 ° C. for 1 hour to obtain a ceria-containing alumina powder (containing 3 wt% of CeO 2).
In addition to drying and calcination in preparing the catalyst powders of the above Examples and Comparative Examples, drying and calcination in preparing the catalyst described later were all performed in an air atmosphere.

(Preparation of the photoconductor protective agent of Example 1)
Example 1 After mixing rhodium powder with zinc stearate melted at 150 ° C. at a blending ratio of zinc stearate 95% and rhodium powder A 5%, it was molded into a block shape and solidified as shown in FIG. Was obtained.

(Preparation of the photoconductor protective agent of Example 2)
The mixture was molded, molded and solidified at a blending ratio of 95% zinc stearate and 5% rhodium powder B to obtain a photoreceptor protective agent of Example 2.

(Preparation of the photoconductor protective agent of Example 3)
The photosensitive material protective agent of Example 3 was obtained by mixing, molding and solidifying at 95% zinc stearate, rhodium powder A 2.5%, and rhodium powder B 2.5%.

(Preparation of photoconductor protective agent of Example 4)
The photosensitive material protective agent of Example 4 was obtained by mixing, molding and solidifying at 95% zinc stearate, 3% rhodium powder A, 1% palladium powder and 1% rhodium powder B.

(Preparation of photoconductor protective agent of Example 5)
A photoconductor of Example 5 was obtained in the same manner as in Example 1 except that zinc stearate 95%, rhodium powder B 4.6%, palladium powder 0.2% and platinum powder 0.2%.

(Preparation of photoconductor protective agent of Comparative Example 1)
A photoconductor protective agent of Comparative Example 1 was obtained in the same manner as in Example 1 except that the rhodium powder of the photoconductor protective agent of Example 1 was replaced with palladium powder.

(Preparation of photoconductor protective agent of Comparative Example 2)
A photoconductor protective agent of Comparative Example 2 was obtained in the same manner as in Example 1 except that the rhodium powder of Example 1 was replaced with platinum powder.

(Preparation of photoconductor protective agent of Comparative Example 3)
A photoconductor protective agent of Comparative Example 3 was obtained in the same manner as in Example 1 except that the rhodium powder of Example 1 was changed to alumina powder containing no catalyst.

(Preparation of photosensitive member protective agent of Comparative Example 4)
In the production of the photoconductor protective agent of Example 1, it was molded with 100% zinc stearate and solidified to obtain a photoconductor protective agent of Comparative Example 4.

After the photoconductor protective agent obtained was installed in a protective layer forming device and installed in a modified Ricoh copy machine Pro1357 *, it was run through 30K half-tone images in an environment of 10 ° C and 15% RH. Then, the image density unevenness immediately under the charger was evaluated. For evaluation of the image density unevenness, 1 × 1 image written alternately by 1 dot, 2 × 2 image written alternately by 2 dots, and 4 × 4 image written alternately by 4 dots were evaluated by using one each. Note that the concentration difference due to NOx exposure tends to appear in the order of 1 × 1, 2 × 2, 4 × 4.

* Linear speed 700 mm / sec, Scorotron charging method, writing wavelength 780 nm, writing laser beam diameter 45 × 55 μm, average toner particle size 5.8 μm

  When the photoconductor protective agents of Examples 1 to 5 according to the present invention were applied to the photoconductor, there was almost no halftone density difference even immediately under the charger. For 1 × 1 images, the density difference detection sensitivity is high, so there is a slight variation in density. However, in normal text images and photographic images, the difference between exposed and unexposed areas is not known at all, and there is no practical problem. It was good.

On the other hand, the photoconductor of the comparative example which does not depend on the present invention shows the density difference between the exposed part and the unexposed part even in the 2 × 2 halftone image, and the density difference can be seen even in a normal character image or photographic image. It turned out to be undesirable.
It can be seen that the presence of rhodium powder is indispensable for fatty acid metal zinc alone, white powder, and alumina powder in order to improve the resistance of NOx with the photoreceptor protective agent. Furthermore, it has been found that the addition of rhodium powder, palladium powder and platinum powder in combination improves NOx resistance.

JP 2005-227470 A Japanese Utility Model Publication No. 62-089660 Japanese Patent Laid-Open No. 2003-43894 Japanese Unexamined Patent Publication No. 2007-121460 JP 2010-210802 JP JP 2010-079130

DESCRIPTION OF SYMBOLS 100 Photoconductor 101 Charging apparatus 102 Image exposure system 103 Developing apparatus 104 Transfer apparatus 105 Photoconductor protective agent
106 Protective Agent Supply Mechanism 107 Protective Layer Forming Mechanism 108 Neutralizing Device 109 Copy Paper 110 Pressing Force Applying Mechanism

Claims (8)

A photoconductor protective agent used in an image forming process including a step of applying or adhering a protective agent to the surface of an electrophotographic photosensitive member, wherein the photoconductor protective agent contains a metal salt of a fatty acid and a metal oxide, and the metal The oxide includes rhodium. Photoconductor protective agent. 2. The photoconductor protective agent according to claim 1, wherein the metal oxide comprises one or more metal oxides and contains at least one of CeO2, Al2O3, and ZrO2. 3. The photoconductor protective agent according to claim 1, further comprising a metal oxide containing at least one of platinum, palladium, and lanthanum in addition to rhodium contained in the metal oxide. The photoconductor protective agent according to claim 1, which is solidified by compression molding. A photosensitive member protective layer forming apparatus for applying or adhering a photosensitive member protective agent to the surface of an electrophotographic photosensitive member, wherein the photosensitive member protective agent is the photosensitive member protective agent according to claim 1. A photosensitive member protective layer forming apparatus. 6. The photosensitive member protective layer forming apparatus according to claim 5, wherein the photosensitive member protective agent is supplied to the surface of the photosensitive member through a supply member. An image forming apparatus comprising the photosensitive member protective layer forming apparatus according to claim 5. A process cartridge comprising the photosensitive member protective layer forming apparatus according to claim 5.

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