JP2005292720A - Electrophotographic photoreceptor and image forming apparatus using the electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly-functional electrophotographic photoreceptor which is free of light scattering and reflection, has low surface energy, and has superior surface smoothness, and maintains such surface characteristics as above in terms of durability, and an image forming apparatus which uses the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor is formed of a photosensitive layer on a conductive base and the electrophotographic photoreceptor is characterized in that the photosensitive layer contains polyolefin particles of ≤4 μm in mean particle size, having been subjected to surface oxidation processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor and an image forming apparatus using the electrophotographic photoreceptor. More specifically, the present invention relates to an electrophotographic photoreceptor containing specific polyolefin resin particles and an image forming apparatus using the electrophotographic photoreceptor.

Electrophotographic technology is widely used in copiers, various printers, facsimiles and the like because of its immediacy and high quality images. For the photoreceptors that form the core of electrophotographic technology, inorganic photoconductive materials such as amorphous silicon and arsenic-selenium and organic photoconductive materials are used.
Several layers have been devised as a layer structure of the organic photoreceptor, but a so-called multilayer photoreceptor in which a charge generation layer and a charge transport layer are separated by separating the functions of charge generation and charge transport, and a charge generation material and charge A so-called single-layer type photoreceptor containing a transport material in the same layer is generally used. As a layer structure of the laminated type photoreceptor, a normal laminated type photosensitive layer in which a charge transport layer and a charge generation layer are laminated in this order from the conductive support side, and a reverse laminated type photosensitive layer in which layers are reversed are known.

  The electrophotographic process is repeatedly charged, exposed, developed, transferred, cleaned, neutralized, etc., so it has various durability, stability, such as physical, mechanical, chemical, and electrical properties. Sex is required. In particular, the durability of organic photoreceptors against mechanical contact with developers, transfer materials, corona discharge products, cleaning blades and the like is inferior to inorganic photoreceptors. In addition, with the recent development of finer developer particles and high-spherical chemical polymerization toners aimed at higher resolution and higher image quality, there is an increasing demand for easy transferability of toner and high-precision cleaning characteristics. ing.

In order to achieve easy transferability of toner and high-accuracy cleaning characteristics, it is necessary to reduce the energy related to the frictional force and adhesion force on the surface of the photoconductor. In addition, the use of a silicone leveling agent, specifically, a method of adding silicone oil or the like to the surface layer, or a method of dispersing a surface modifier such as Teflon resin powder or silicone resin powder in the surface layer is known.
Specifically, for example, it has been reported that silicone oil is added (for example, see Patent Document 1) and that a fluororesin powder is contained (for example, see Patent Document 2).

Further, the addition of polyolefin particles to improve the surface properties of the electrophotographic photosensitive member includes a method using a surface-oxidized polyethylene powder (for example, see Patent Document 3) and a resin having a specific particle size. It has been proposed to add particles (for example, see Patent Document 4).
JP 11-352707 A JP 2002-40684 A JP-A-2-143257 Japanese Patent No. 2740313

However, these commonly used surface modifiers are, for example, leveling agents, which are poorly compatible with the coating liquid components, so that during the coating film drying process or during a relatively short period of storage. The leveling agent easily moves to the surface and segregates on the extreme surface of the surface layer. Therefore, although the surface energy can be effectively reduced in the initial stage, the leveling agent is easily scraped off while the surface is repeatedly rubbed, and the effect is lost immediately and there is a problem in sustainability. . Further, for example, when resin fine particles are dispersed in the photosensitive layer, the lubricity is improved and the effect is maintained, but the difference in refractive index between the Teflon fine particles and the photosensitive layer is large. Even if the particle size is not appropriate, the light for forming an incident latent image may be scattered and reflected to prevent the formation of a faithful latent image. Polyethylene wax, which has a molecular weight smaller than that of polyethylene resin, is relatively easy to produce particles with a small particle size. However, since it is soluble in the solvent used in the photoreceptor coating solution, a small amount of dissolved component is deposited on the surface. In some cases, the electrical characteristics were adversely affected. In particular, in recent years, it has been found that processes using dot-like minute latent images such as lasers, LEDs, and liquid crystal shutters controlled by digital signals have a large influence on these and greatly reduce image uniformity.

  On the other hand, as described above, recent toner developers tend to have smaller particle sizes and lower glass transition temperatures for higher resolution, higher image quality, and higher speed. This means that transfer efficiency is reduced due to increased adhesion, and filming is likely to occur. At present, there is a long-awaited demand for photoreceptors with more sophisticated surface characteristics.

  That is, the object of the present invention is a high-performance electrophotographic photosensitive member that has no light scattering or reflection, low surface energy, excellent surface slipperiness or surface releasability, and that maintains its surface characteristics even in durability, and An object of the present invention is to provide an image forming apparatus using the photoreceptor.

  As a result of intensive studies on the above problems, the present inventors have found that the surface energy can be reduced extremely effectively by including specific polyolefin resin particles in the photosensitive layer, and that the effect is also sustainable. The headline has led to the present invention. That is, the gist of the present invention is an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein the outermost surface layer contains polyolefin resin particles having a particle size of 4 μm or less that are surface-oxidized. A photoreceptor and an image forming apparatus using the photoreceptor.

  The electrophotographic photosensitive member using specific particles in the photosensitive layer according to the present invention has excellent surface characteristics, and the surface characteristics persist even after repeated use, so that a stable image can always be formed. . In addition, there is almost no adverse effect on the photoconductive properties such as sensitivity and photoresponsive properties due to the inclusion of the particles, and the durability is excellent, and an image forming apparatus such as a high-speed copying machine or a color printer with extremely high quality is provided. Can be provided.

The description of the constituent requirements described below is an example of embodiments of the present invention, and is not specified by these contents.
As the polyolefin resin particles used in the present invention, particles such as polyethylene, polypropylene, poly 1-butylene, polyisobutylene, poly 1-pentene, poly 1-hexene can be used, or a copolymer selected from these particles. It may be a coalescence. Among these, polyethylene or polypropylene is preferable, and polyethylene is particularly preferable. The particles may be a copolymer with a monomer other than polyolefin as required, such as styrene, acrylic acid esters, methacrylic acid esters, acrylamide, vinyl chloride, vinylidene chloride, vinylidene fluoride, and tetrafluoride. A copolymer with ethylene or the like can be used. Further, a mixture of these homopolymers or copolymers may be used.

Usually, the average particle diameter of the polyolefin resin particles is 4 μm or less, and particularly preferably 3 μm or less. If the particle size is larger than 4 μm, the resolution of the obtained image is adversely affected. On the other hand, if the particle size is too small, it is difficult to obtain the effect of improving the surface properties, so that it is preferably 0.1 μm or more, and particularly preferably 0.3 μm or more. The average particle diameter referred to here is a median value based on volume, and this can be generally measured using a method such as a laser diffraction method or a dynamic light scattering method.

If the molecular weight of the polyolefin resin particles is too small, it may partially dissolve in the photoreceptor coating solution and affect the performance. Therefore, the number average molecular weight of the resin used is usually 2000 or more, preferably 3000 or more, more preferably 5000. That is the above, and 100,000 or less is usually used.
The polyolefin resin particles in the present invention are those obtained by oxidizing the surface in order to improve the affinity with the binder resin. Any known oxidation treatment method can be used for this surface treatment. Examples include corona discharge treatment, dry treatment such as ozone treatment, and wet treatment in contact with an aqueous solution of dichromate, permanganate, hypochlorite, hydrogen peroxide, persulfate, etc. In order to treat the water uniformly, a wet treatment is preferable. In order to oxidize relatively small particles as in the present invention, it is preferable to use an oxidizing agent having a relatively mild oxidizing power such as an aqueous persulfate solution so as not to be attacked by a short-time reaction.

  The particles of the present invention are contained in the outermost surface layer of the photosensitive layer, but when contained in the normal laminated photosensitive layer, they are usually 0.01 parts by weight or more, preferably 0 parts per 100 parts by weight of the binder resin of the charge transport layer. .1 part by weight or more, more preferably 0.5 part by weight or more and usually 30 parts by weight or less, preferably 20 parts by weight or less, more preferably 15 parts by weight or less. The same amount ratio is also used when it is contained in the single-layer type photosensitive layer.

When used for a photoreceptor having an overcoat layer, the layer is contained, and the content in that case is 0.1 parts by weight or more with respect to 100 parts by weight of the resin component of the overcoat layer. , Preferably in the range of 50 parts by weight or less.
The overcoat layer referred to here includes a protective layer for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to a discharge product generated from a charger or the like.

The protective layer is formed by containing a conductive material in an appropriate binder resin, or has a charge transporting ability such as a triphenylamine skeleton described in JP-A Nos. 9-190004 and 10-252377. A copolymer using a compound can be used.
Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.

  As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Also, a copolymer of the above resin and a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377 can be used.

The electrical resistance of the protective layer is usually in the range of 10 ⁹ Ω · cm to 10 ¹⁴ Ω · cm. If the electric resistance is higher than the above range, the residual potential is increased, resulting in an image with much fog. On the other hand, if the electric resistance is lower than the above range, the image is blurred and the resolution is reduced. Further, the protective layer must be configured so as not to substantially prevent transmission of light irradiated during image exposure.
In addition, the particles of the present invention can be used with a visible light source, not just near infrared lasers and LEDs, which are usually used as exposure light, so that exposure to white light or a relatively short wavelength blue light is possible. Exposure with LED or laser is also possible.

<Support>
The photosensitive layer of the present invention is provided on a conductive support. Although there is no restriction | limiting in particular as an electroconductive support body, For example, what made the metal material, such as aluminum, stainless steel, copper, nickel, into the drum shape, and electroconductive layers, such as aluminum, copper, palladium, tin oxide, and indium oxide, on the surface Polyester film with paper, insulating support such as paper, sheets, belts, drums, rolls, and conductive fine particles such as carbon and copper powder mixed with plastic or paper are used. The

The surface of the support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use the drawing tube as it is without performing the cutting process.
In the case of using an aluminum drum, the material used is, for example, an extruded or drawn tube of aluminum alloy such as 3000 series, 5000 series, 6000 series, etc., which is regulated by JIS, or a machined product thereof. The maximum surface roughness Rmax is preferably 2.5 μm or less.
Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. The film thickness when the anodized film is applied is preferably 1 to 10 μm, for example, and it is desirable to perform a sealing treatment with nickel acetate or the like by a known method.

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used.
Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.

In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is usually 1 nm or more, preferably 10 nm or more, and usually 100 nm or less. Preferably it is 50 nm or less.
The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. As binder resin used for the undercoat layer, epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitro Cellulose ester resins such as cellulose, cellulose ether resins, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelation Things, organic zirconium compounds such as zirconium alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanyl alkoxide compound, a known binder resin such as a silane coupling agent and the like. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

The ratio of the inorganic particles to the binder resin used in the undercoat layer can be arbitrarily selected, but is usually in the range of 10% by weight or more and 500% by weight or less from the viewpoint of dispersion stability and coating properties. Is preferably used.
The thickness of the undercoat layer can be arbitrarily selected, but from the viewpoint of improving the photoreceptor characteristics and coating properties, it is usually in the range of 0.05 μm to 20 μm, preferably 0.1 μm to 10 μm.
A known antioxidant or the like may be mixed in the undercoat layer. For the purpose of preventing image defects, pigment particles, resin particles and the like may be contained and used.

<Photosensitive layer>
The constitution of the photosensitive layer that can carry out the present invention may be a single layer type photosensitive layer or a laminated type photosensitive layer. Further, in the laminated photosensitive layer, either a forward laminated photosensitive layer or a reverse laminated photosensitive layer can be employed.

<Charge generation layer>
In the case of a laminated photosensitive layer, the charge generating material used in the charge generating layer generally includes inorganic photoconductive materials and organic photoconductive materials, and among them, organic photoconductive materials, particularly organic pigments are preferred. For example, azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, indigo pigments, benzimidazole pigments, pyrylium salts, thiapyrylium salts, squalium salts, and the like can be used, and phthalocyanine pigments or azo pigments are particularly preferable. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.

When organic pigments and / or salts are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.
The binder resin used for the charge generation layer is not particularly limited, but examples include polyvinyl butyral resin, polyvinyl formal resin, polyvinyl acetal type such as partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal, acetal, or the like. Resin, Polyarylate resin, Polycarbonate resin, Polyester resin, Modified ether type polyester resin, Phenoxy resin, Polyvinyl chloride resin, Polyvinylidene chloride resin, Polyvinyl acetate resin, Polystyrene resin, Acrylic resin, Methacrylic resin, Polyacrylamide resin, Polyamide Resin, polyvinyl pyridine resin, cellulosic resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride Vinyl chloride-vinyl acetate copolymer such as vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer Insulating resin such as polymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin, poly-N-vinylcarbazole, polyvinylanthracene, polyvinylperylene Organic photoconductive polymers such as Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

Specifically, the charge generation layer is prepared by dispersing the halogen-substituted indium phthalocyanine of the present invention and other charge generation materials used in some cases in a solution obtained by dissolving the above binder resin in an organic solvent. Is applied on a conductive support (or an undercoat layer when an undercoat layer is provided).
The solvent used for preparing the coating solution is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, and aromatics such as toluene, xylene, and anisole. Group solvents, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene, amide solvents such as dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, etc. Alcohol solvents, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chain or cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, methylene chloride , Chloro Halogenated hydrocarbon solvents such as rum, 1,2-dichloroethane, chain ether or cyclic ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, acetonitrile, dimethyl Aprotic polar solvents such as sulfoxide, sulfolane, hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine, triethylamine and other nitrogen-containing compounds, ligroin and other mineral oils, water, etc. Can be mentioned. Any one of these may be used alone, or two or more of these may be used in combination. In addition, when providing the above-mentioned undercoat layer, what does not melt | dissolve this undercoat layer is preferable.

  In the charge generation layer, the blending ratio (weight) of the binder resin and the charge generation material is usually 10 parts by weight or more, preferably 30 parts by weight or more, and usually 1000 parts by weight with respect to 100 parts by weight of the binder resin. The film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material, while if the ratio of the charge generation material is too low, the sensitivity as a photoreceptor may be decreased. There is.

As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.
In addition, the charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving the coating property as necessary. Furthermore, a vapor deposition film of the above substance may be used.

<Charge transport layer>
The charge transport layer may be formed of a binder resin having a charge transport function alone, but a configuration in which a charge transport material is dispersed in the binder resin is more desirable.
Examples of the binder resin used in the charge transport layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, epoxy, and silicone. Resins etc. are mentioned, and these partially crosslinked cured products can also be used.

Examples of the charge transport material include polycyclic aromatic compounds such as pyrene and anthracene, heterocyclic compounds such as carbazole, indole, oxazole, thiazole, pyrazoline, oxathiazole, thiadiazole, and triazole, p-diethylaminobenzaldehyde-N, N-diphenyl Hydrazone compounds such as hydrazone, N-methylcarbazole-3-carbaldehyde-N, N-diphenylhydrazone, and 5- (4- (di-p-tolylamino) benzylidene) -5H-dibenzo (a, d) cycloheptene. Styryl compounds, triarylamine compounds such as p-tolyltolylamine, benzidine compounds such as N, N, N, N-tetraphenylbenzidine, butadiene compounds, and tris such as di- (p-ditolylaminophenyl) methane Phenylmethane Such compounds.

The ratio of the binder resin and these charge transport materials is usually 30 to 200 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin.
Further, the charge transport layer may contain various additives such as antioxidants such as hindered phenols and hindered amines, ultraviolet absorbers, sensitizers, leveling agents, and electron-withdrawing substances as necessary. The charge transport layer has a thickness of 10 to 60 μm, preferably 10 to 45 μm.
As the outermost surface layer, a conventionally known overcoat layer mainly composed of, for example, a thermoplastic or thermosetting polymer may be provided.

<Single layer type photosensitive layer>
When the photosensitive member has a single-layer type photosensitive layer, the charge generation material is dispersed in the matrix mainly composed of the binder resin and the charge transport material having the above-described mixing ratio. The particle diameter must be sufficiently small, preferably 1 μm or less, more preferably 0.5 μm or less.
If the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained, and if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. It is used at 50% by weight, more preferably 10 to 45% by weight. The thickness of the photosensitive layer is usually 5-5.
It is used at 0 μm, more preferably 10 to 45 μm. Also in this case, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersion stability, coatability Leveling agents, surfactants, silicone oils, fluorine oils and other additives may be added to improve the properties.

<Layer formation method>
Each layer constituting these photoreceptors is formed by immersing, coating, spraying, nozzle coating, bar coating, roll coating, blade coating, etc., on a support, a coating solution obtained by dissolving or dispersing a substance to be contained in a solvent. In this method, the coating and drying steps are sequentially repeated for each layer.
There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1, Chlorinated hydrocarbons such as 2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine , Nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. These may be used alone or in combination, and two or more may be used in any combination and type.

The amount of the solvent or dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriate so that the physical properties such as solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of a charge transport layer layer of a single layer type photoreceptor and a function separation type photoreceptor, the solid content concentration of the coating solution is usually 5% by weight or more, usually 5% by weight or more, preferably 10% by weight or more, Moreover, it is usually 40% by weight or less, preferably 35% by weight or less. Further, the viscosity of the coating solution is usually in the range of 10 cps or more, preferably 50 cps or more, and usually 500 cps or less, preferably 400 cps or less.

In the case of a charge generating layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by weight or more, preferably 1% by weight or more, and usually 15% by weight or less, preferably 10% by weight. % Or less. The viscosity of the coating solution is usually 0.01 cps or more, preferably 0.1 cps or more, and usually 20 cps or less, preferably 10 cps or less.
Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. The heating temperature may be constant or the heating may be performed while changing the temperature during drying.

<Image forming apparatus>
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5, a cleaning device 6, and a fixing device as necessary. A device 7 is provided.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. Examples of the charging device include a corona charging device such as a corotron and a scorotron, a direct charging device (contact type charging device) that charges a direct charging member to which a voltage is applied by contacting the photosensitive member surface, and a contact type charging device such as a charging brush. Often used. Examples of direct charging means include contact chargers such as charging rollers and charging brushes. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2. As the direct charging means, either charging with air discharge or injection charging without air discharge is possible. Moreover, as a voltage applied at the time of charging, it is possible to use only a direct current voltage or to superimpose an alternating current on a direct current.

The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. .

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, or two-component magnetic brush development, or a wet development method is used. be able to. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicon resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.
The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. As the upper and lower fixing members 71 and 72, known heat fixing members such as a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll coated with Teflon resin, or a fixing sheet are used. be able to. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may have a configuration capable of performing, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.
The electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( The electrophotographic photosensitive member cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded. In the following, “part” represents “part by weight”.

<Oxidation treatment of polyethylene resin particles>
<Processing Example 1>
5 g of polyethylene resin particles having an average particle diameter of 2 μm (Mn = 20000: GPC method polystyrene conversion) were dispersed in 100 g of water using 0.1 g of sodium dodecyl sulfate, and 7 g of potassium persulfate was added thereto. This dispersion was heated at 70 ° C. for 1 hour, and polyethylene resin particles were taken out by filtration. This was washed with water and then with methanol, and then dried under reduced pressure at 50 ° C. for 12 hours to obtain 4.2 g of surface-oxidized polyethylene resin particles having an average particle diameter of 2 μm.

<Processing example 2>
Using the same polyethylene resin particles as in <Processing Example 1>, surface-oxidized polyethylene resin particles were produced in the same manner as in <Processing Example 1> except that the heating condition was 50 ° C. for 8 hours.
<Processing example 3>
Surface-oxidized polyethylene resin particles were produced in the same manner as in <Processing Example 1> except that polyethylene resin particles (Mn = 27000) having an average particle diameter of 6 μm were used.

Example 1
10 parts of oxotitanium phthalocyanine showing a clear peak at a diffraction angle 2θ ± 0.2 ° of 27.3 ° in a powder X-ray diffraction pattern by CuKα ray, polyvinyl butyral (manufactured by Denki Kagaku Kogyo KK, trade name: # 6000C) 5 parts of 1,2 dimethoxyethane was added and pulverized and dispersed in a sand grind mill. The dispersion thus obtained was applied on a polyethylene terephthalate film having aluminum deposited on the surface so as to have a film thickness of 0.3 μm to provide a charge generation layer.
Next, on this film, 50 parts of the hole transporting compound shown below and

  0.05 parts of silicone oil (product name KF96 manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts of polycarbonate resin having the following structural units

A coating solution in which 10 parts by weight of the surface oxidized polyethylene particles obtained in <Processing Example 1> are dispersed in a solution of 1000 parts of a mixed solvent of tetrahydrofuran and toluene (volume ratio 8: 2) is applied with a film applicator. The charge transport layer was provided so that the film thickness after drying was 12 μm. The photoreceptor thus prepared is referred to as a photoreceptor A.

Example 2
In Example 1, in the same manner as in Example 1 except that 10 parts by weight of the surface oxidized polyethylene resin particles obtained in <Treatment Example 2> was used instead of the surface oxidized polyethylene resin particles obtained in <Treatment Example 1>. The photosensitive member B was manufactured.

Comparative Example 1
In Example 1, Example 1 was used except that the surface-oxidized polyethylene resin particles obtained in <Processing Example 1> were replaced with 10 parts by weight of untreated polyethylene resin particles having an average particle diameter of 2 μm (Mn = 20000). A comparative photoconductor C was prepared in the same manner as described above.
Comparative Example 2
In Example 1, in place of the surface-oxidized polyethylene resin particles obtained in <Treatment Example 1>, 10 parts by weight of the surface-oxidized polyethylene resin particles obtained in <Treatment Example 3> was used. Then, a comparative photoconductor D was produced.
Comparative Example 3
A comparative photoconductor E was produced in the same manner as in Example 1 except that the surface-oxidized polyethylene resin particles were not added.

<Evaluation of electrical characteristics>
These electrophotographic photoreceptors were cut into a size of 100 mm in width and 250 mm in length, wound around an aluminum tube having a diameter of 80 mm so that the photosensitive layer was on the outside, and fixed using a double-sided adhesive tape. At this time, the four corners of the photosensitive layer are removed with a cloth soaked in tetrahydrofuran to expose the aluminum vapor-deposited surface. One end of the conductive adhesive tape is attached to this portion, and one end of the tape is attached to the aluminum tube. Then, the conductive support of the photoreceptor and the aluminum tube were made conductive.

The performance evaluation sample thus obtained was mounted on a photoreceptor characteristic evaluation apparatus installed in an environmental test room at a temperature of 25 ° C. and a relative humidity of 50%. After charging the surface potential of the electrophotographic photosensitive member to be −700 V, irradiation with 780 nm light was performed while changing the irradiation intensity, and the surface potential after 100 milliseconds was measured. The residual potential (Vr unit -V) at this time is shown in Table-1. The exposure intensity at which the photoreceptor surface potential after exposure to 780 nm light becomes −350 V after 100 msec is defined as half exposure intensity (E / 2 unit μJ / cm ² ), and this value is shown in Table 1.

<Evaluation of surface properties>
The above-mentioned electrophotographic photosensitive member was cut into a size of 60 mm in width and 130 mm in length, and fixed with an adhesive tape on a reciprocating table of a FR-2 type abrasion tester manufactured by Suga Test Instruments Co., Ltd. A load of 7.8 N was applied, and polishing was performed by reciprocating 300 times on the electrophotographic photosensitive member using a 3M Wetdry Tri-M-ite Paper 2000. Thereafter, a load of 7.8 N was applied, and polishing was performed by reciprocating 300 times on the electrophotographic photosensitive member with JK Wiper (registered trademark) 150-S manufactured by Crecia Corporation.

The coefficient of friction of the electrophotographic photosensitive member before and after polishing was measured using a Heidon-14 type surface property tester manufactured by Shinto Kagaku Co., Ltd. At this time, a nonwoven fabric SOFPADS manufactured by Dynic Co., Ltd. having a width of 10 mm and a length of 12 mm was used as the friction body, and measurement was performed under a load of 2.9 N and a sweep speed of 100 mm / min. The results are shown in Table-1.
Furthermore, the contact angle with pure water was measured for the electrophotographic photoreceptor after polishing using a FACE CA-D contact angle meter manufactured by Kyowa Interface Science Co., Ltd. The results are shown in Table-1.

Example 3
A charge generation layer coating solution and a charge transport layer coating solution were prepared in the same manner as in Example 1. This coating solution is successively dip-coated on an aluminum tube having a diameter of 30 mm and a length of 346 mm and an alumite-treated surface to laminate a charge generation layer having a thickness of 0.4 μm after drying and a charge transport layer having a thickness of 25 μm To form a photoconductor.

  This photoconductor was mounted on a digital copier DP3200 manufactured by Matsushita Electric Industrial Co., Ltd., and the first and 1000th printed images were compared, but no change was observed. Further, no change was observed in the friction coefficient and contact angle of the photoreceptor, and it was confirmed that the surface modification effect was sustained.

  The electrophotographic photosensitive member using specific particles in the photosensitive layer according to the present invention has excellent surface characteristics, and the surface characteristics persist even after repeated use, so that a stable image can always be formed. It is possible to provide an image forming apparatus such as a high-speed copying machine or a color printer with extremely high quality.

It is a figure which shows an example of the image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Charging device 3 Exposure device 4 Developing device 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 5 Transfer device 6 Cleaning device 7 Fixing device 71 Upper fixing member 72 Lower fixing member 73 Heating device

Claims (5)

An electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein the outermost surface layer contains surface-oxidized polyolefin resin particles having an average particle diameter of 4 μm or less. 2. The electrophotographic photosensitive member according to claim 1, wherein the number average molecular weight of the polyolefin resin forming the particles is 2000 or more. The electrophotographic photosensitive member according to claim 1, wherein the polyolefin resin particles are polyethylene resin particles. 4. The electrophotographic photosensitive member according to claim 1, wherein the surface oxidation treatment is an oxidation treatment in a solution. An electrophotographic photosensitive member according to any one of claims 1 to 4, a charging unit for charging the photosensitive member, an image exposing unit for performing image exposure on the charged photosensitive member to form an electrostatic latent image, An image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target.

Images