JP2006201542A - Electrophotographic photoreceptor and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor the surface of which is little deteriorated and which has very good mechanical durability, and executes stable image formation over a prolonged period of time. <P>SOLUTION: The electrophotographic photoreceptor is used in an image forming apparatus and includes: at least an electrophotographic photoreceptor; a charger which is disposed in contact or contiguity with the electrophotographic photoreceptor and charges the electrophotographic photoreceptor by making use of discharge caused by applying a voltage obtained by superimposing an AC component on a DC component; a latent image forming unit which forms an electrostatic latent image on a surface of the electrophotographic photoreceptor charged by the charger; and a developing unit which deposits toner on the image area of the electrostatic latent image formed by the latent image forming unit. The electrophotographic photoreceptor has at least a photosensitive layer on a conductive support and contains carbon-based nanoparticles having an average particle diameter of ≤20 nm in a surface of the photoreceptor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic process employed in an electrophotographic process having a charger that charges an electrophotographic photosensitive member by using a discharge generated by applying a voltage in which an alternating current component is superimposed on a direct current component that is provided in contact with or in close proximity. The present invention relates to a photographic photosensitive member, an image forming apparatus, a process cartridge for the image forming apparatus, and an image forming method.

In recent years, miniaturization and higher image quality have been demanded for electrophotographic apparatuses from the viewpoints of saving office space and expanding business opportunities.
Many attempts have been made to improve the electrophotographic process in order to reduce the size of the electrophotographic apparatus. However, in the charging process, a charging method using proximity discharge tends to be frequently employed. This is a system in which a charging member is brought into contact with the surface of the electrophotographic photosensitive member, or a charging member is disposed in the vicinity without contact to generate a proximity discharge to charge the surface of the electrophotographic photosensitive member. If this method is used, a large-scale charging device is not required, and thus it is very effective for downsizing the device. Also, recent proximity charging systems often employ a system in which an AC voltage is applied in a superimposed manner on a DC voltage in order to achieve uniform charging on the electrophotographic photosensitive member.

  However, the charging method using proximity discharge in which AC voltage is superimposed on DC voltage concentrates the discharge near the surface of the electrophotographic photosensitive member, so the surface of the electrophotographic photosensitive member is deteriorated and the thickness of the electrophotographic photosensitive member is greatly reduced. It was. Deterioration of the electrophotographic photosensitive member surface due to proximity discharge occurs even when there is no contact member to the image carrier, unlike mechanical rubbing. For this reason, development of an electrophotographic photosensitive member having durability against proximity discharge or a technology for protecting the surface of the electrophotographic photosensitive member is strongly desired.

The deterioration mechanism of the electrophotographic photoreceptor surface due to proximity discharge will be described below.
FIG. 1 shows a state in which only a charging member is placed close to the surface of the electrophotographic photosensitive member in a non-contact state in order to investigate the deterioration state of the surface of the electrophotographic photosensitive member due to the proximity discharge, and a charging experiment is performed for about 150 hours continuously. 3 is a result of measuring a change in film thickness on the surface of the electrophotographic photosensitive member.

  The electrophotographic photosensitive member used in the experiment is an organic photosensitive member using polycarbonate for the charge transport layer, and all the members in contact with the electrophotographic photosensitive member are removed, and an alternating voltage in which an alternating voltage is superimposed on a direct current voltage is applied. Charging was performed using a non-contact charging roller. As a result, it was found that the amount of film scraping on the surface of the electrophotographic photosensitive member gradually increased and the film thickness of the electrophotographic photosensitive member gradually decreased. The mechanism of film thickness reduction has not been clarified at present. However, when an electrophotographic photosensitive member having a reduced film thickness is analyzed, the polycarbonate constituting the electrophotographic photosensitive member is considered to have been decomposed. Acid etc. were detected.

Since such a substance has been detected, the following may be considered as a mechanism for reducing the film thickness of the electrophotographic photosensitive member.
FIGS. 2A and 2B show the state of the surface of the electrophotographic photosensitive member when the surface of the electrophotographic photosensitive member 1 deteriorates due to proximity discharge, and shows the state where the charging roller 2a is opposed to the surface of the electrophotographic photosensitive member with a minute gap. It is explanatory drawing shown taking as an example.

  When proximity discharge is performed, the energy of particles (ozone, electrons, excited molecules, ions, plasma, etc.) generated by the discharge is irradiated to the charge transport layer 1a on the surface of the electrophotographic photoreceptor in the discharge region on the surface of the electrophotographic photoreceptor. . This energy resonates and is absorbed by the binding energy of the molecules constituting the surface of the electrophotographic photosensitive member, and as shown in FIG. 2 (a), the charge transport layer 1a has a lower molecular weight due to cleavage of the resin molecular chain, Chemical degradation such as a decrease in the degree of entanglement occurs. It is considered that the film thickness of the charge transport layer 1a on the surface of the electrophotographic photosensitive member gradually decreases due to the chemical deterioration of the electrophotographic photosensitive member due to such proximity discharge.

  This problem is not only a problem that occurs in a photoreceptor using polycarbonate, but polyarylate (see Patent Document 1), polystyrene (see Patent Document 2), acrylic resin (see Patent Document 3), and urethane resin (see Patent Document 4). ) Etc., the same film thickness reduction occurs, and this problem has not been solved.

JP 2003-195564 A Japanese Patent Laid-Open No. 10-90932 Japanese Patent No. 3262488 JP 2004-12865 A

  The present invention is a charging method using proximity discharge in which an AC voltage is superimposed on a DC voltage, and the surface of the electrophotographic photosensitive member is hardly deteriorated, the mechanical durability is very good, and stable image formation is performed over a long period of time. An object of the present invention is to provide an electrophotographic photosensitive member and an image forming method.

As a result of intensive studies, the present inventors have found that the purpose of the previous term can be achieved by using the photoreceptors described in (1) to (8) below, and have achieved the present invention.
(1) “At least an electrophotographic photosensitive member and an electrophotographic photosensitive member using a discharge generated by applying a voltage in which an alternating current component is superimposed on a direct current component provided in contact with or close to the electrophotographic photosensitive member. A charger for charging the toner, a latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charger, and a toner on an image portion of the electrostatic latent image formed by the latent image forming device. An electrophotographic photosensitive member used in an image forming apparatus having a developing device for adhering a toner, the photosensitive member having at least a photosensitive layer on a conductive support, and carbon having an average particle diameter of 20 nm or less on a surface of the photosensitive member as a main component. Electrophotographic photosensitive member characterized by containing nano-particles that can be used ",
(2) "The electrophotographic photosensitive member according to (1) above, wherein the carbon has a diamond structure",
(3) “The electrophotographic photosensitive member according to (1) or (2) above, which has a surface layer on the photosensitive layer”,
(4) "The electrophotographic photosensitive member according to (3) above, wherein the surface layer contains at least one polymer of polycarbonate, polyester, and polyether",
(5) "The electrophotographic photosensitive member according to (4) above, wherein the surface layer contains a charge transport material",
(6) “The surface layer is a cross-linked resin layer obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure. (3) The electrophotographic photosensitive member described in the above,
(7) “The electrophotographic photosensitive member according to (6) above, wherein the radical polymerizable compound having a charge transporting structure used in the surface layer is monofunctional”;
(8) "The electrophotographic photosensitive member according to any one of (1) to (7) above, wherein the photosensitive layer has a structure in which a charge generation layer and a charge transport layer are sequentially laminated",

In addition, as a result of intensive studies, the present inventors have found that the purpose of the previous period can be achieved by using the image forming apparatus described in (9) below, and have achieved the present invention.
(9) “An electrophotographic photosensitive member utilizing at least an electrophotographic photosensitive member and a discharge generated by applying a voltage in which an alternating current component is superimposed on a direct current component provided in contact with or close to the electrophotographic photosensitive member. A charger for charging the toner, a latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charger, and a toner on an image portion of the electrostatic latent image formed by the latent image forming device. An image forming apparatus having a developing device for adhering the electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to (1) to (8) above, ”

Further, the above problem is solved by a process cartridge described in (10) below and an image forming method described in (11) below.
(10) “A process cartridge comprising the electrophotographic photosensitive member according to the above (1) to (8).
(11) “An image forming method, wherein an image is formed using the image forming apparatus described in (9).

Charging that charges the electrophotographic photosensitive member using at least an electrophotographic photosensitive member and a discharge generated by applying a voltage in which the alternating current component is superimposed on a direct current component that is in contact with or close to the electrophotographic photosensitive member. , A latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging device, and development for attaching toner to an image portion of the electrostatic latent image formed by the latent image forming device. In the image forming apparatus having a container, the electrophotographic photosensitive member has at least a photosensitive layer on a conductive support, and the surface of the photosensitive member contains nanoparticles having an average particle diameter of 20 nm or less as a main component. The electrophotographic photosensitive member is characterized in that the electrophotographic photosensitive member is less deteriorated due to charging, has high wear resistance, has good electrical characteristics, and has high durability and high performance. Photoreceptor is obtained.
Therefore, by using this electrophotographic photosensitive member, it is possible to provide a high-performance and highly reliable image forming process, an image forming apparatus, and a process cartridge for the image forming apparatus that can provide good images over a long period of time.

Hereinafter, the present invention will be described in detail.
The present invention relates to an electrophotographic photosensitive member using at least an electrophotographic photosensitive member and a discharge generated by applying a voltage in which an alternating current component is superimposed on a direct current component provided in contact with or close to the electrophotographic photosensitive member. A charger for charging the toner, a latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charger, and a toner on an image portion of the electrostatic latent image formed by the latent image forming device. In the image forming apparatus having a developing unit for adhering the toner, the electrophotographic photosensitive member has at least a photosensitive layer on a conductive support, and a nano particle mainly composed of carbon having an average particle diameter of 20 nm or less on the surface of the photosensitive member. This is achieved by an electrophotographic photosensitive member characterized by containing fine particles.

  As a result of intensive studies by the inventor, when a charger using a charging method based on proximity discharge in which an AC voltage is superimposed on a DC voltage is used, not only mechanical durability but also particles (ozone, electrons, It has been found that it has extremely high durability against energy irradiation of excited molecules, ions, plasma, and the like.

  According to Onishi et al. (J. Electrochem. Soc., 130, 1, 143-146 (1983)), in the dry etching process, the number of carbons in the resist film structure correlates with the etching rate, and as the number of carbons increases. It is known that the etching rate decreases.

  Even in the charging method using proximity discharge in which an alternating voltage is superimposed on a direct current voltage, it is considered that a plasma state is generated in the discharge region in the discharge region, and by containing nano-particles mainly composed of carbon, Since the amount of carbon in the film increases, it is considered that the durability is improved.

When the nanoparticle mainly composed of carbon has a large particle size, the surface roughness of the photoreceptor increases. In the case of a photoreceptor having a large surface roughness, when toner is developed on the surface of the photoreceptor, the toner is likely to be scattered, which causes the toner to be scattered on the image and to cause background contamination. In addition, the cleaning property is lowered, which causes an abnormal image.
As a result of investigations by the present inventors, the surface of the photoreceptor is good when the average particle size of the nano-particles mainly composed of carbon is 20 nm or less.

In addition, when the average particle size is 50 nm or less, preferably 20 nm or less, the nanoparticle mainly composed of carbon is detached from the film surface and becomes a micro-bearing during long-term use, thereby improving the lubricity of the photoreceptor surface. This reduces the surface friction coefficient and improves the cleaning properties. Furthermore, when the toner shape is spherical, the effect is remarkable.
When the nanoparticle having carbon as a main component is a particle having a diamond structure, the mechanical durability is further improved and the wear resistance is improved.

The diamond structure is a fine particle having a diamond structure having SP ³ orbits. In addition to the diamond structure, particles having a similar structure such as a graphite structure having an SP ² orbit and an amorphous carbon structure may be used. Further, it is not limited to only carbon, but may contain other elements such as hydrogen, oxygen, nitrogen, fluorine, boron, phosphorus, chlorine, bromine and iodine.

As a method for producing nano-particles mainly composed of carbon, there are a solid phase method such as a pulverization method, a vapor phase method such as CVD and PVD, and a liquid phase method.
As a particularly good method for producing fine particles, a method (ultra-high pressure explosion method) in which diamond fine particles are formed under a high temperature and high pressure by exploding trinitrotoluene or the like in a sealed container in an inert gas atmosphere can be exemplified. The diamond fine particles obtained by this method are then classified to obtain fine particles having a desired particle size.
Hereinafter, the layer structure of the present invention will be described.

<About the layer structure of the electrophotographic photoreceptor>
The electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 3 is a cross-sectional view showing the electrophotographic photosensitive member of the present invention. The electrophotographic photosensitive member has a single layer structure in which a photosensitive layer having a charge generating function and a charge transporting function is provided on a conductive support. is there. In this case, fine particles mainly containing carbon are contained in the photosensitive layer.
FIG. 4 shows a surface layer provided on the photosensitive layer of FIG. In this case, fine particles mainly containing carbon are contained in the surface layer.
FIG. 5 shows an electrophotographic photosensitive member having a multilayer structure in which a charge generation layer having a charge generation function and a charge transport layer having a charge transport material function are stacked on a conductive support. In this case, the charge transport layer contains fine particles mainly composed of carbon.
FIG. 6 shows a surface layer provided on the charge transport layer of FIG. In this case, fine particles mainly containing carbon are contained in the surface layer.

<About 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. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.
In addition, the conductive support dispersed in an appropriate binder resin on the support can be used as the conductive support of the present invention.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned. The binder resin used at the same time includes 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, melamine Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as resins, urethane resins, phenol resins, and alkyd resins. Such a conductive layer can be provided by dispersing and applying 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.

<About photosensitive layer>
Next, the photosensitive layer will be described. The photosensitive layer may have a laminated structure or a single layer structure.
In the case of a laminated structure, the photosensitive layer is composed of a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. In the case of a single layer structure, the photosensitive layer is a layer having a charge generation function and a charge transport function at the same time.
Hereinafter, each of the photosensitive layer having a laminated structure and the photosensitive layer having a single layer structure will be described.

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

  As a binder resin used as necessary for the charge generation layer, 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, benzidine skeleton, hydrazone skeleton, carbazole skeleton, stilbene skeleton, 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.

  Specific examples of the former include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559, Japanese Unexamined Patent Publication Nos. 04-011627, 04-175337, 04-183719, 04-2225014, 04-230767, 04-320420, 05 -232727, JP-A 05-310904, JP-A 06-234836, JP-A 06-234837, JP-A 06-234838, JP-A 06-234839, JP-A 06-234840. No. 1, JP-A 06-234841, JP-A 06-239049, Japanese Unexamined Patent Publication Nos. 06-236050, 06-236051, 06-295077, 07-0756374, 08-176293, 08-208820, 08 No. -21640, JP 08-252868, JP 08-269183, JP 09-062019, JP 09-038883, JP 09-71642, JP 09-87376. JP-A 09-104746, JP-A 09-110974, JP-A 09-110976, JP-A 09-157378, JP-A 09-221544, JP-A 09-227669. JP-A 09-228367, JP-A 09-241369 Charge transporting polymer materials described in JP 09-268226 A, JP 09-272728 A, JP 09-302084 A, JP 09-302085 A, JP 09-328539 A, etc. Can be mentioned.

  Specific examples of the latter include polysilylene polymers described in, for example, JP-A No. 63-285552, JP-A No. 05-19497, JP-A No. 05-70595, JP-A No. 10-73944, and the like. Illustrated.

The charge generation layer may contain a charge transport material.
Charge transport materials that can be used in the charge generation 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.

Methods for forming the charge generation layer 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 coating can be performed using a dip coating method, spray coating, bead coating, ring coating method 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.

(About charge transport layer)
The charge transport layer is a layer having a charge transport function.
The charge transport layer is formed by dissolving or dispersing a charge transport material having a charge transport function and a binder resin in an appropriate solvent, and coating and drying the solution on the charge generation layer.
As the charge transport material, the electron transport material and the hole transport material described in the charge generation layer can be used.

Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene 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, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin.

  As the solvent used for the charge transport layer, the same solvent as that 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 the plasticizer that can be used in combination with the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.
Examples of leveling agents that can be used in 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. About 0 to 1 part by weight is appropriate for the part by weight.
The thickness of the charge transport layer is suitably about 5 to 40 μm, preferably about 10 to 30 μm.

<Single photosensitive layer>
A photosensitive layer having a single layer structure is a layer having both a charge generation function and a charge transport function.
The photosensitive layer can be formed by dissolving or dispersing a charge generation material having a charge generation function, a charge transport material having a charge transport function, and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed. As the charge generation material dispersion method, the charge generation material, the charge transport material, the plasticizer, and the leveling agent may be the same as those already described in the charge generation layer and the charge transport layer. As the binder resin, in addition to the binder resin previously mentioned in the section of the charge transport layer, the binder resin mentioned in the charge generation layer may be mixed and used. In addition, the polymer charge transport materials mentioned above can also be used. The film thickness of the photosensitive layer is suitably about 5 to 30 μm, preferably about 10 to 25 μm.
The charge generating material contained in the photosensitive layer having a single layer structure is preferably 1 to 30% by weight based on the total amount of the photosensitive layer, the binder resin contained in the photosensitive layer is 20 to 80% by weight, and the charge transporting material is 10%. ~ 70 parts by weight are used favorably.

<Addition of nanoparticle mainly composed of carbon to photosensitive layer>
When the photosensitive layer having a single layer or a laminated structure is the outermost layer, nanoparticles having carbon having an average particle size of 20 nm or less as a main component are added to the outermost layer portion. In the case of a single layer structure, a nanoparticle mainly composed of carbon having an average particle size of 20 nm or less is dispersed in a charge generating material having a charge generating function, a charge transporting material having a charge transporting function, and a binder resin to form a film.
In the case of a laminated structure, a nanoparticle mainly composed of carbon having an average particle diameter of 20 nm or less is dispersed in a charge generation material used as a charge transport layer and a binder resin to form a film. The abundance of the nanoparticles is preferably 5 to 20% by weight.

<About surface layer>
In the photoreceptor of the present invention, a surface layer may be provided on the photosensitive layer.
The binder resin used for the surface layer is ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene. , Polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polychlorinated Examples thereof include resins such as vinyl, polyvinylidene chloride, and epoxy resin.

Among these, polycarbonate, polyester, and polyether resin are effectively used.
Nanoparticles mainly composed of carbon having an average particle size of 20 nm or less and a binder resin are dissolved or dispersed in a suitable solvent, and this is applied and dried.
If necessary, an appropriate amount of a charge transport material, a plasticizer, an antioxidant, a leveling agent, and the like can be added.

The thickness of the surface layer is preferably in the range of 1.0 to 10.0 μm. If it is too thin, it tends to wear out and disappear during long-term use, and if it is thick, it can be considered that the residual potential increases and the fine dot reproducibility decreases.
The solid content concentration of the binder resin in the surface layer is 20 to 80 wt%, preferably 40 to 70 wt%.

  Further, a crosslinked resin layer obtained by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure is effectively used. Furthermore, a crosslinked resin layer obtained by curing a tri- or higher functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure is particularly effectively used.

  The trifunctional or higher functional radical polymerizable monomer having no charge transporting property used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group. And a monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a nitro group and having three or more radical polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) 1-Substituted Ethylene Functional Group Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = _{CH-X 1} -
(However, in the formula, X1 is an arylene group such as a phenylene group and a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group, —CON (R ₁₀ ) — group (R ₁₀ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Or represents a —S— group.)
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) 1,1-Substituted Ethylene Functional Group Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = _{CY-X 2} -
(In the formula, Y is an aryl group such as an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group. Group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl which may have a substituent, a phenethyl group or the like, an aryl group such as a phenyl group or a naphthyl group which may have a substituent, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group, or Ara such phenethyl group, Kill group or substituent a phenyl group which may have a represents an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is the same substituent as X1 in the formula 10 A group, a single bond, or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.)
Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.

  In addition, examples of the substituent further substituted with the substituent for X and Y include, for example, a halogen atom, a nitro group, an alkyl group such as a cyano group, a methyl group, and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, Examples thereof include aryloxy groups such as phenoxy group, aryl groups such as phenyl group and naphthyl group, aralkyl groups such as benzyl group and phenethyl group.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

Specific examples of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure include the following, but are not limited to these compounds.
That is, examples of the radical polymerizable monomer used in the present invention include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, and PO-modified. Trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH-modified glycerol triacrylate, EO-modified glycerol triacrylate , PO-modified glycerol triacrylate, Lith (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl Modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO modified phosphoric acid triacrylate, 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate, etc. These may be used alone or in combination of two or more.

  Moreover, the component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used for the surface layer is 20 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of the crosslinked surface layer. When the monomer component is less than 20% by weight, the three-dimensional cross-linking density of the cross-linked surface layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it is 80% by weight or more, the content of the charge transporting compound is lowered, and the electrical characteristics are deteriorated. Since the required wear resistance and electrical characteristics differ depending on the process used, it cannot be said unconditionally, but considering the balance of both characteristics, the range of 30 to 70% by weight is most preferable.

  The radical polymerizable compound having a charge transporting structure used in the present invention includes a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group and nitro group. It refers to a compound having an electron transport structure such as an electron-withdrawing aromatic ring and having a radical polymerizable functional group. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful.

  In addition, as the radical polymerizable compound having a charge transporting structure, a polyfunctional compound having two or more functional groups can be used, but a monofunctional compound is preferable in terms of film quality and electrostatic characteristics. This is because when a bifunctional or higher functional charge transport compound is used, it is fixed in the crosslinked structure by a plurality of bonds. However, since the charge transport structure is very bulky, distortion occurs in the cured resin, resulting in a crosslinked surface layer. This is because the internal stress of the film increases, and it becomes easy to cause cracks and scratches due to carrier adhesion and the like.

  In addition, in terms of electrostatic characteristics, when a bifunctional or higher functional charge transporting compound is used, it is fixed in the crosslinked structure with a plurality of bonds, so that the intermediate structure (cation radical) during charge transport is stably maintained. In other words, the sensitivity is lowered due to charge trapping, and the residual potential is likely to increase. Such deterioration of the electrical characteristics appears as an image such as a decrease in image density and thinning of characters. For this reason, the radical polymerizable compound having a charge transporting structure uses a radical polymerizable compound having a monofunctional charge transporting structure and is fixed in a pendant shape between crosslinks, thereby causing cracks and scratches. And stabilization of electrostatic characteristics can be achieved.

  The surface layer in the present invention is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a charge transporting structure. In order to advance well, a polymerization initiator may be used in the crosslinked surface layer.

Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, peroxide initiators such as lauroyl peroxide, azobisisobutylnitrile, azobiscyclohexanecarbonitrile Azo initiators such as methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid.
Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of photopolymerization initiators and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoic acid. Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound is mentioned.

Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples thereof include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the coating liquid of the present invention can contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity as required. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20% by weight or less, preferably 10% or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

  The crosslinked surface layer of the present invention is obtained by applying and curing a coating liquid containing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure, a radical polymerizable compound having a charge transport structure, and filler fine particles. It is formed. When the radically polymerizable monomer is a liquid, such a coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied.

  Solvents used at this time include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane and propyl ether. And ethers such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary.

  In the present invention, after applying such a coating solution, energy is applied from the outside and cured to form a crosslinked surface layer. The external energy used at this time includes heat, light, and radiation. The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. If the heating temperature is lower than 100 ° C., the reaction rate is slow and the reaction is not completely completed. At a temperature higher than 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the crosslinked surface layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more.

As the energy of light, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in ultraviolet light, can be used, but a visible light source can also be selected according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform and the cross-linked surface layer becomes very rough. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

As a method of providing a surface layer on the photosensitive layer, a dip coating method, a ring coating method, a spray coating method, or the like is used.
Among these, a general method for forming a surface layer is a spray that forms a coating film by depositing fine droplets generated by discharging a paint from a nozzle having a fine opening and atomizing it onto the photosensitive layer. A coating method is used.

<About the undercoat layer>
In the electrophotographic photoreceptor of the present invention, an undercoat layer can be provided between the conductive support and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodization, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
Further, in the present invention, in order to improve environmental resistance, each layer such as a surface layer, a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer, etc., in particular for the purpose of preventing a decrease in sensitivity and an increase in residual potential. An antioxidant can be added to the.
The following are mentioned as antioxidant which can be used for this invention.

(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (28-di-t-butyl-4-hydroxy Phenyl) propionate, 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 ′ -Thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy) -5-tert-butylphenyl) butane, 1,28-trimethyl-2,4,6-tris (28-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- ( ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] clico- Luester, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.

(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

<Image Forming Method and Apparatus>
Embodiments of an image forming apparatus to which the present invention is applied will be described below. However, these are just examples, and the present invention is not limited to these. FIG. 7 shows an example of an image forming apparatus having a configuration common to the embodiments described later. This image forming apparatus includes an electrophotographic photosensitive member made of an organic photosensitive member. The electrophotographic photoreceptor 1 is characterized in that it is a film having at least a photosensitive layer and nano-particles mainly composed of carbon having an average particle diameter of 20 nm or less on the surface of the photoreceptor.

<About the overall configuration>
In FIG. 7, the electrophotographic photosensitive member 1 is rotationally driven by a driving device (not shown), and the surface thereof is charged to a predetermined polarity by a charging roller 2a of a charging device 2 of a proximity charging type. The surface of the charged electrophotographic photosensitive member 1 is exposed by the exposure device 3 to form an electrostatic latent image corresponding to the image information. The electrostatic latent image is developed with toner as a developer supplied from the developing device 4 to the surface of the electrophotographic photosensitive member 1 to be visualized as a toner image.

  On the other hand, a transfer sheet as a recording medium is fed toward the electrophotographic photosensitive member 1 from a paper feeding unit (not shown). A toner image on the electrophotographic photosensitive member 1 is transferred onto the transfer paper on the transfer paper by a transfer device 5 disposed opposite to the electrophotographic photosensitive member 1. The transfer paper onto which the toner image has been transferred is separated from the electrophotographic photosensitive member 1 and then conveyed to the fixing device 6 along the transfer material conveyance path 10 to fix the toner image.

  Transfer residual toner as residual toner remaining on the electrophotographic photosensitive member 1 after the toner image is transferred to the transfer paper is removed from the electrophotographic photosensitive member 1 by the cleaning blade 8 of the cleaning device 7. Further, the residual charge on the surface of the electrophotographic photosensitive member after the transfer residual toner is removed is removed by the static eliminator 9. In this way, the electrophotographic photoreceptor 1 is repeatedly used.

  In the image forming apparatus according to the present embodiment, the electrophotographic photosensitive member, the charging member, the developing device, and the cleaning device are integrally configured as a process cartridge that is detachable from the image forming apparatus main body.

<About charging>
Next, the charging device 2 used in the image forming apparatus will be described. The charging device 2 charges the electrophotographic photosensitive member using proximity discharge. As a method of charging the electrophotographic photosensitive member using proximity discharge, a contact charging method in which a rotatable roller-shaped charging member (hereinafter referred to as a charging roller) 2a is placed in contact with the electrophotographic photosensitive member, and charging is performed. There is a non-contact charging method in which a roller is disposed in a non-contact manner on an electrophotographic photosensitive member. In this embodiment, a non-contact charging method is used.

  The present invention can also be applied to a contact charging method. However, in the contact charging method, it is preferable to use an elastic member that improves the contact property with the surface of the electrophotographic photosensitive member and does not apply mechanical stress to the electrophotographic photosensitive member. However, when an elastic member is used, the charging nip width is widened, which may cause the protective material to easily adhere to the charging roller side. Therefore, it is more advantageous to adopt a non-contact charging method for high durability. The first embodiment employs a non-contact charging method in which the charging roller 2a is disposed so as to face at least an image forming area on the surface of the electrophotographic photosensitive member with a predetermined charging gap.

FIG. 8 is an explanatory diagram of the charging device 2 used in the image forming apparatus according to the first embodiment.
The charging roller 21 includes a shaft portion 21a and a roller portion 21b. The roller portion 21 b can be rotated by the rotation of the shaft portion 21 a, and a portion of the surface of the electrophotographic photosensitive member 1 that faces the image forming region 11 where an image is formed is not in contact with the electrophotographic photosensitive member 1. The length of the charging roller 21 in the longitudinal direction (axial direction) is set slightly longer than the image forming area, and spacers 22 are provided at both ends in the longitudinal direction. By bringing these two spacers 22 into contact with the non-image forming regions 12 at both ends of the surface of the electrophotographic photosensitive member 1, a minute gap 14 is formed between the electrophotographic photosensitive member 1 and the charging roller.

  The minute gap 14 is configured so that the distance at the closest portion between the charging roller 21 and the electrophotographic photosensitive member 1 can be maintained at 1 to 100 μm. A more preferable range of the gap 14 is 10 to 80 μm, and more preferably 30 to 65 μm. In the apparatus of the first embodiment, the gap 14 is set to 50 μm. Further, the shaft portion 21a is pressed against the electrophotographic photosensitive member side by a pressing spring 15 made of a spring. Thereby, the minute gap 14 can be accurately maintained. The charging roller 21 rotates along with the surface of the electrophotographic photosensitive member via the spacer 22.

  A charging power source 16 is connected to the charging roller 21. As a result, the surface of the electrophotographic photosensitive member is uniformly charged by proximity discharge in a minute gap between the surface of the electrophotographic photosensitive member and the surface of the charging roller. As the applied voltage, an AC voltage is superimposed on a DC voltage. When an alternating voltage obtained by superimposing an AC voltage on a DC voltage is used as the applied voltage, the effect of variations in charging potential due to minute gap fluctuations is suppressed, and uniform charging becomes possible. In the first embodiment, an alternating voltage obtained by superimposing an AC voltage that is an AC component on a DC voltage that is a DC component is used.

  The charging roller 21 has a cored bar as a conductive support having a cylindrical shape and a resistance adjusting layer formed on the outer peripheral surface of the cored bar. The surface of the charging roller 21 is preferably hard. A rubber member can also be used as the roller member. However, if the member is easily deformed, such as a rubber member, it is difficult to maintain the minute gap 14 with the electrophotographic photosensitive member 1 uniformly. There is a possibility that only the central portion suddenly contacts the surface of the electrophotographic photosensitive member. The charging roller 21 is preferably a hard member with less deflection when the non-contact charging method is used.

  Specific examples of the charging roller 21 having a hard surface include, for example, a thermoplastic resin composition (polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and a copolymer thereof, etc.) in which a polymer ion conductive agent is dispersed in a resistance adjustment layer. ), And the surface of the resistance adjustment layer is cured with a curing agent. The cured film treatment is performed, for example, by immersing the resistance adjustment layer in a treatment solution containing an isocyanate-containing compound, but may be performed by forming a cured treatment film layer on the surface of the resistance adjustment layer. In the present embodiment, the charging roller 2a is formed with a diameter of 10 mm (diameter 10 mm).

  As is apparent from the above description, the electrophotographic photosensitive member of the present invention is not only used in electrophotographic copying machines, but also in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making. Can also be used widely.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. All parts are by weight.

[Example 1]
An undercoat layer coating solution was applied to an Al support (outer diameter: 30 mmφ) by an immersion method so that the film thickness after drying was 28 μm to form an undercoat 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-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
40 parts of titanium oxide
(CR-EL: Ishihara Sangyo)
50 parts of methyl ethyl ketone

  On this undercoat layer, a charge generation layer coating solution having the following composition containing a bisazo pigment was dip coated and dried by heating to form a 0.2 μm thick charge generation layer.

<Coating liquid for charge generation layer>
Bisazo pigment of the following chemical formula 2.5 2.5 parts polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part cyclohexanone 200 parts methyl ethyl ketone 80 parts

  On this charge generation layer, a charge transport layer coating solution having the following composition was dip-coated and dried by heating to obtain a charge transport layer having a thickness of 22 μm.

<Coating liquid for charge transport layer>
Bisphenol N-type polycarbonate 10 parts Charge transport material of the following chemical formula 2 10 parts Tetrahydrofuran 80 parts 1% silicone oil in tetrahydrofuran 0.2 parts (KF50, manufactured by Shin-Etsu Chemical Co., Ltd.)

On this charge transport layer, a surface layer coating solution having the following composition was spray coated and dried by heating at 150 ° C. to form a surface layer having a thickness of 5.0 μm.
<Coating liquid for surface layer>
Charge transport material used for charge transport layer
Bisphenol A-type polycarbonate diamond fine particles (Nanodiamond, average particle size 4-8nm, Beijing National Rising Technology Co., Ltd.)
Tetrahydrofuran cyclohexanone
(Mixing ratio (weight))
Charge transport material / polycarbonate / diamond fine particles / tetrahydrofuran / cyclohexanone = 4.5 / 5 / 0.5 / 170/50

[Example 2]
It was produced in the same manner as in Example 1 except that the following carbon fine particles were added in place of the diamond fine particles used in Example 1.
Carbon fine particles (carbon black HCF # 2600, average particle size 13 nm, Mitsubishi Chemical)

[Example 3]
It was produced in the same manner as in Example 1 except that the following carbon particles were added instead of the diamond fine particles used in Example 1.
Carbon fine particles (carbon black MCF88, average particle size 18nm, Mitsubishi Chemical)

[Comparative Example 1]
All were produced in the same manner as in Example 1 except that the surface layer was not provided.

[Comparative Example 2]
It was produced in the same manner as Example 1 except that diamond fine particles were not added to the surface layer.

[Comparative Example 3]
It was produced in the same manner as in Example 1 except that the following carbon fine particles were added in place of the diamond fine particles used in Example 1.
Carbon fine particles (carbon black LFM MA-8, average particle size 24 nm, Mitsubishi Chemical)

[Comparative Example 4]
It was produced in the same manner as in Example 1 except that the following carbon fine particles were added in place of the diamond fine particles used in Example 1.
Carbon fine particles (carbon black LFM MA220, average particle size 55 nm, Mitsubishi Chemical)

[Example 4]
It was produced in the same manner as in Example 1 except that the following coating solution and film forming method were used instead of the surface layer coating solution in Example 1.

<Surface layer coating solution>
10 parts of radically polymerizable monomer having 3 or more functional groups not having a charge transporting structure (KAYARAD TMPTA: manufactured by Nippon Kayaku)
Radical polymerizable compound having a monofunctional charge transport structure of the following chemical formula 3 9 parts Photopolymerization initiator 0.5 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Diamond fine particles 1 part (Nanodiamond, average particle size 4-8nm, Beijing National Rising Technology Co., Ltd.)
Tetrahydrofuran 80 parts After spray coating, UV irradiation was performed, followed by heat drying (130 ° C., 20 minutes).

[Comparative Example 5]
All were produced in the same manner as in Example 5 except that diamond fine particles were not added to the surface layer.

(Real machine paper test)
Using the Ricoh IPSiO Color CX9000 having a non-contact charging device that applies a voltage in which an alternating current component is superimposed on a direct current component, the produced electrophotographic photosensitive member is tested using an actual machine (A4, My Paper manufactured by NBS Ricoh, at start). Photoreceptor surface charging potential -650 V) was performed, and wear characteristics and image (S3 chart) characteristics were evaluated. The results are shown in Tables 1, 2, 3, and 4.
Also, using a Ricoh IPSiO Color CX9000 modified to a contact charger that applies only a DC component voltage, an actual paper feeding test (A4, NBS Ricoh My Paper, photoreceptor surface charging potential at start-700 V) was performed. The wear characteristics were evaluated. The results are shown in Tables 5 and 6.

  The electrophotographic photoreceptor of the present invention can be suitably used as an electrophotographic photoreceptor in an image forming apparatus that employs a charging method based on proximity discharge in which an alternating voltage is superimposed on a direct current voltage.

It is a figure which shows the relationship between a run time and the amount of film | membrane abrasions when the electrophotographic photosensitive member is charged. It is the figure which showed typically the state in which the surface of the electrophotographic photoreceptor 1 deteriorates by proximity discharge. 1 is a cross-sectional view illustrating an example of an electrophotographic photosensitive member of the present invention. 1 is a cross-sectional view illustrating an example of an electrophotographic photosensitive member of the present invention. 1 is a cross-sectional view illustrating an example of an electrophotographic photosensitive member of the present invention. 1 is a cross-sectional view illustrating an example of an electrophotographic photosensitive member of the present invention. 1 is a diagram illustrating a configuration example of an image forming apparatus of the present invention. 1 is a diagram illustrating a configuration of a charging device used in an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photosensitive member 2 Charging apparatus 2a Charging roller 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Fixing apparatus 7 Cleaning apparatus 8 Cleaning blade 9 Static elimination apparatus 10 Transfer material conveyance path 11 Image forming area 12 Non-image forming area 14 Gap 15 Addition Pressure spring 16 Power source 21 Charging roller 21a Shaft portion 21b Roller portion 22 Spacer

Claims (11)

  Charging that charges the electrophotographic photosensitive member using at least an electrophotographic photosensitive member and a discharge generated by applying a voltage in which the alternating current component is superimposed on a direct current component that is in contact with or close to the electrophotographic photosensitive member. , A latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging device, and development for attaching toner to an image portion of the electrostatic latent image formed by the latent image forming device. An electrophotographic photosensitive member used in an image forming apparatus having a container, comprising at least a photosensitive layer on a conductive support, and nanoparticle mainly composed of carbon having an average particle diameter of 20 nm or less on the surface of the photosensitive member. An electrophotographic photosensitive member containing the electrophotographic photosensitive member.   The electrophotographic photosensitive member according to claim 1, wherein the carbon has a diamond structure.   3. The electrophotographic photosensitive member according to claim 1, further comprising a surface layer on the photosensitive layer.   4. The electrophotographic photosensitive member according to claim 3, wherein the surface layer contains at least one polymer of polycarbonate, polyester, and polyether.   The electrophotographic photosensitive member according to claim 4, wherein the surface layer contains a charge transport material.   The said surface layer is a crosslinked resin layer which hardened | cured the radically polymerizable compound which has the radically polymerizable compound which has a charge transportable structure and the trifunctional or more than trifunctional radically polymerizable monomer which does not have a charge transportable structure at least. Electrophotographic photoreceptor.   7. The electrophotographic photoreceptor according to claim 6, wherein the radical polymerizable compound having a charge transporting structure used for the surface layer is monofunctional.   The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a structure in which a charge generation layer and a charge transport layer are sequentially laminated.   Charging that charges the electrophotographic photosensitive member using at least an electrophotographic photosensitive member and a discharge generated by applying a voltage in which the alternating current component is superimposed on a direct current component that is in contact with or close to the electrophotographic photosensitive member. , A latent image forming device for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging device, and development for attaching toner to an image portion of the electrostatic latent image formed by the latent image forming device. An image forming apparatus comprising: an image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 8.   A process cartridge comprising the electrophotographic photosensitive member according to claim 1.   An image forming method comprising forming an image using the image forming apparatus according to claim 9.

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