JP2007072276A - Electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent image deletion in a high temperature and high humidity environment and to obtain a long life of an electrophotographic photoreceptor in an electrophotographic apparatus using a cleanerless system in which a residual toner after a transfer step is recovered by a developing means. <P>SOLUTION: The electrophotographic apparatus is equipped with a developer charge amount control means to charge a developer remaining on an electrophotographic photoreceptor after a transfer step, and the apparatus is characterized in that: the developing means recovers the toner remaining on the electrophotographic photoreceptor after a transfer step; the electrophotographic photoreceptor shows an elastic deformation rate of 45% to 65% in terms of surface hardness; the initial surface roughness Rzjis (ten-point average surface roughness) of the electrophotographic photoreceptor is 0.3 μm to 1.3 μm; and the initial maximum height Rz is less than 2.0 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleanerless electrophotographic apparatus.

  2. Description of the Related Art Conventionally, an electrophotographic apparatus using an electrophotographic system such as a copying machine, a printer, or a facsimile is an electrophotographic photosensitive member that is a latent image carrier, a charging unit that charges the photosensitive member, and a static image formed on the photosensitive member. Developing means for visualizing the electrostatic latent image with toner as developer, transfer means for transferring the visualized toner onto a transfer material such as paper, and cleaning for cleaning residual toner remaining on the photoreceptor thereafter And fixing means for fixing the toner on the transfer material.

  As an electrophotographic photoreceptor, the photosensitive wavelength range can be freely controlled by selecting the dye or pigment to be used, and it has advantages such as good film forming properties, high productivity, and low cost. Electrophotographic photoreceptors using organic photoconductive materials are widely used. Since this organic electrophotographic photoreceptor is composed of a thin resin layer in which a charge generating material or a charge transporting material is dissolved or dispersed on a conductive substrate, the mechanical durability is inferior to that of an inorganic photoreceptor. Have. Various developments have been made to improve durability, but in recent years a proposal has been made to reduce the amount of photoconductor abrasion and extend the life by providing a hard surface layer on the electrophotographic photoreceptor. (For example, see Patent Documents 1 and 2).

  On the other hand, in order to reduce the size of the entire electrophotographic apparatus, reduce the amount of waste toner, and reduce the amount of photoconductor wear, a cleaner that recycles the residual transfer toner recovered by the cleaning means to the developing means for reuse. Less electrophotographic devices have been developed. As one of the methods, a copying machine or a printer that employs a method in which a developing unit collects residual toner after transfer has been proposed (see, for example, Patent Document 3).

  In the electrophotographic apparatus using the cleanerless system in which the developing means collects the residual toner after transfer, there is no step of cleaning the transfer residual toner on the surface of the electrophotographic photosensitive member with a cleaning member. The amount of wear is reduced, and the life of the electrophotographic photosensitive member can be improved. (For example, refer to Patent Document 4).

However, in an electrophotographic apparatus using a cleanerless system in which the developing means collects the residual toner after transfer, deposits on the surface of the electrophotographic photosensitive member generated in the electrophotographic process cannot be removed by the cleaning member. For this reason, when a photoconductor using a surface layer with high hardness is used in a cleanerless type electrophotographic apparatus, even if the charged product generated in the process of charging the photoconductor adheres to the photoconductor, it is not removed. There has been a problem that image flow occurs in a high humidity environment.
JP 2000-66425 A JP 2004-012986 A Japanese Patent Laid-Open No. 05-053482 JP 2004-240303 A

  The present invention has been made in consideration of the above-described problems, and in the electrophotographic apparatus using the cleanerless system in which the developing unit collects the residual toner after transfer, the electrophotographic photosensitive member has a long life. An object of the present invention is to provide an electrophotographic apparatus capable of preventing the occurrence of image flow in a high temperature and high humidity environment and obtaining a good image over a long period of time.

The electrophotographic apparatus according to the present invention is:
An electrophotographic photoreceptor;
Charging means for charging the electrophotographic photosensitive member;
Information writing means for forming an electrostatic latent image on a charged electrophotographic photosensitive member;
Developing means for supplying a developer to visualize the electrostatic latent image;
Means for transferring the visualized developer image to a transfer material;
Developer charge amount control means for charging the developer remaining on the electrophotographic photosensitive member after the transfer step;
An electrophotographic apparatus comprising:
The developing means collects toner remaining on the electrophotographic photosensitive member after transfer,
There is no cleaning means for collecting and storing the toner remaining on the electrophotographic photosensitive member after transfer between the transfer means and the charging means and between the charging means and the developing means,
The electrophotographic photoreceptor is
An electrophotographic photosensitive member having a conductive support and a photosensitive layer laminated on the conductive support,
The elastic deformation rate at the surface hardness of the electrophotographic photoreceptor is 45% or more and 65% or less,
The initial surface roughness: Rzjis (ten-point average surface roughness) of the electrophotographic photosensitive member is 0.3 μm or more and 1.3 μm or less, and the initial maximum height Rz is less than 2.0 μm. And

  According to the present invention, it is possible to prevent the image flow particularly in a high-temperature and high-humidity environment and to extend the life of the electrophotographic photosensitive member.

  The electrophotographic apparatus according to the present invention will be described in detail.

  FIG. 1 shows an example of a cleanerless system in which a developing unit collects residual toner after transfer according to the present invention. In FIG. 1, the electrophotographic photoreceptor 1 rotates in the direction of the arrow and is charged by the charging means 2. Thereafter, image information is written as an electrostatic latent image by the exposure means 3, and the electrostatic latent image is visualized as a toner image by the developing means 4. The visualized toner image on the surface of the photoconductor is transferred onto the transfer material P by the transfer means 5. In this transfer step, the untransferred toner remaining on the surface of the photosensitive member without being transferred is charged to the same polarity as the above-mentioned charge by the developer charge amount control unit 7, and passes through the above-described charging unit 2 and exposure unit 3. It is used again for development or collected in a developing device.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the charging unit 2, the developing unit 4, and the developer charge amount control unit 7 described above are integrally supported as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer.

  The charging means 2 is a method of charging the electrophotographic photosensitive member without contact with the electrophotographic photosensitive member, such as proximity charging, or contact charging in which the electrophotographic photosensitive member is charged by contacting a conductive roller, brush, blade, or the like. A method or an injection charging method is used.

  In addition, when the electrophotographic apparatus is a copying machine or a printer, the image exposure irradiated from the exposure unit 3 is a reflected or transmitted light from a document, or a laser beam that is read in accordance with a signal obtained by reading the document with a sensor. The light is emitted by scanning the light source, driving the LED array, or driving the liquid crystal shutter array.

  As the developing means 4, jumping development, two-component contact development, one-component contact development, or the like is used.

  Examples of the developer charge amount control means 7 include a fixed brush-like member, a brush rotating body, and an elastic roller body.

  In addition to the developer charge amount control means 7, the electrophotographic apparatus according to the present invention may further include an auxiliary device that imparts chargeability to the residual toner on the surface of the electrophotographic photosensitive member 1. FIG. 2 is a diagram illustrating this aspect, and is a schematic diagram illustrating an example of an image forming apparatus that executes the image forming method of the present invention. According to FIG. 2, the electrophotographic apparatus according to this aspect has the transfer means 5 for transferring the toner image visualized on the surface of the electrophotographic photosensitive member 1 to the transfer material P, and remains on the surface of the photosensitive member without being transferred. A residual developer uniforming means 8 is provided between the developer charge amount control means 7 for charging the transfer residual toner with the same polarity as the above-mentioned charging. The residual developer uniformizing means 8 is for uniformizing the residual toner on the surface of the electrophotographic photosensitive member 1. The member of the residual developer uniformizing means 8 can also take any form such as a fixed brush-like member, a brush rotating body, an elastic roller body, and a sheet-like member. In addition, this member can be thrust in the longitudinal direction with respect to the photoconductor to make the potential application property more uniform. Further, it may be grounded or a bias may be applied.

  The electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member having a photosensitive layer or a photosensitive layer and a protective layer on a conductive cylindrical support, and the elastic deformation ratio We of the surface layer of the electrophotographic photosensitive member is 45. % To 65%, initial surface roughness: Rzjis (ten-point average surface roughness) is 0.3 μm to 1.3 μm, and initial maximum height Rz is less than 2.0 μm And By roughening the surface of the photoconductor under the above conditions, the charged product that is the cause of image flow can be easily scraped off by the auxiliary charging member described above. It is estimated that it can be prevented. When the initial surface roughness of the photoconductor is less than 0.3 μm, there is no effect in eliminating image blur, and when it is greater than 1.3 μm, there is a problem that character reproducibility is poor. Further, the maximum height Rz is preferably less than 2.0 μm. When the thickness is 2.0 μm or more, there arises a problem that, as it is repeatedly used, it grows as a scratch due to rubbing with the auxiliary charging member and appears as a white stripe on the halftone image.

  In the surface shape measurement method, the ten-point average roughness (Rzjis) and the maximum height (Rz) in the present invention are those measured in accordance with the method described in JIS-B0601-2001. The measurement was performed using a surface roughness measuring instrument (trade name: Surfcorder SE3500 type, manufactured by Kosaka Laboratory Ltd.).

  Further, when the elastic deformation rate of the photoreceptor surface layer is 45% or more, the change in the surface shape after repeated use becomes small, and the roughening of the present invention becomes more effective. On the other hand, if the elastic deformation rate exceeds 65%, fatal scratches are caused by cracks or instantaneous external impacts.

Furthermore, the universal hardness (HU) of the surface layer of the electrophotographic photoreceptor according to the present invention is preferably 150 or more and 220 N / mm ² or less. If it is less than 150 N / mm ^2, the abrasion resistance of the surface of the photoreceptor is not sufficient, and if it exceeds 220 N / mm ² , scratches are likely to occur due to rubbing with the auxiliary charging member described above.

The elastic deformation rate and universal hardness (HU) are continuous with a Vickers square pyramid diamond indenter having a facing angle of 136 ° in an environment of 25 ° C. and humidity 50% RH using a microhardness measuring device Fischerscope H100V (manufactured by Fischer). This is a value measured by applying a load of 6 mN and directly reading the indentation depth under the load. Specifically, measurement is performed stepwise up to a final load of 6 mN (273 points with a holding time of 0.1 seconds for each point). The elastic deformation rate can be obtained from the work (energy) of the indenter with respect to the film, that is, the change in energy due to the increase or decrease of the load on the film of the indenter. Specifically, the elastic deformation work We is defined as the total work Wt. It is the value divided.
Elastic deformation rate = We / Wt
Further, the universal hardness (HU) can be obtained from the following expression from the indentation depth of the indenter when the final load of 6 mN is applied to the indenter. In the following formula, HU means universal hardness (HU), F _f means the final load, S _f means the surface area of the indented portion when the final load is applied, h _f means the indentation depth of the indenter when the final load is applied.

  In the present invention, the electrophotographic photosensitive member that improves the scratch resistance and abrasion resistance of the peripheral surface of the electrophotographic photosensitive member and can easily obtain the effects of the present invention is polymerized or crosslinked on the surface layer by heating or irradiation. It is preferable to contain a resin that cures. The method for producing a photoreceptor containing a curable resin in the surface layer includes a monomer or oligomer having a polymerizable functional group in the paint, and after film formation and drying, the film is polymerized by heating and irradiation. You may have the process to advance. By this method, three-dimensionally cross-linked and cured to form a tough film-forming layer that is insoluble and infusible in solvents, etc., the amount of wear of the surface layer can be significantly reduced, and in repeated use The initial surface roughness can be maintained, and the effects of the present invention can be obtained over a long period of time.

  The surface layer may have a charge transport function. A case having a charge transport function is treated as a part of the photosensitive layer, and a case having no charge transport function is referred to as a protective layer (or surface protective layer) as described below to distinguish it from the photosensitive layer. In the best constitution of the present invention, it is preferable to obtain a photosensitive layer having a hardened surface by applying a coating containing a charge transporting material having a polymerizable functional group in the same molecule, and then curing the coating. In order to further increase the strength of the hardened layer of the outermost surface layer, it is preferable that two or more polymerizable functional groups exist in the same molecule.

  As the layer structure of the photosensitive layer, a normal layer stack structure in which the charge generation layer / charge transport layer are stacked in this order from the conductive support side, and a reverse layer stack structure in which the charge transport layer / charge generation layer is stacked in this order from the conductive support side. Alternatively, any configuration of a single layer in which the charge generation material and the charge transport material are dispersed in the same layer can be employed.

  In a single photosensitive layer, photocarriers are generated and moved in the same layer, and the photosensitive layer itself is a surface layer. On the other hand, the laminated photosensitive layer has a structure in which a charge generation layer for generating photocarriers and a charge transport layer for moving the generated carriers are laminated.

  The most preferable layer structure is a normal layer structure in which the charge generation layer / charge transport layer are laminated in this order from the conductive support side.

  In this case, the charge transport layer is an electrophotographic photosensitive member that is an outermost surface layer containing a curable resin, or the charge transport layer is a laminated type of a non-curable first layer and a curable second layer. Any of the electrophotographic photoreceptors in which the curable second layer is the outermost surface layer is preferable.

  In either case of a single layer or a laminated layer, it is possible to provide a protective layer above the photosensitive layer. In this case, the protective layer is preferably a curable resin-containing layer on the surface.

  The conductive substrate may be any conductive substrate (conductive support), for example, a metal (alloy) support such as aluminum, nickel, copper, gold, iron, aluminum alloy, and stainless steel. There may be. Also, the above-mentioned metal support or plastic (polyester resin, polycarbonate resin, polyimide resin, etc.) support having a layer formed of a film formed by vacuum deposition of aluminum, aluminum alloy, indium oxide-tin oxide alloy, or the like. A glass support can also be used. In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated into plastic or paper together with an appropriate binder resin, or a plastic support having a conductive binder resin, etc. Can also be used. In addition, examples of the shape of the support include a cylindrical shape and a belt shape, and a cylindrical shape is preferable.

  The surface of the support may be subjected to a cutting process, a roughening process (such as a honing process or a blasting process), an alumite process, or the like for the purpose of preventing interference fringes due to scattering of laser light or the like. Alternatively, chemical treatment may be performed with a solution obtained by dissolving a metal salt compound or a fluorine compound metal salt in an acidic aqueous solution mainly composed of alkali phosphate, phosphoric acid, or tannic acid.

  The honing process includes a dry honing process and a wet honing process. The wet honing treatment is a method in which a powdery abrasive is suspended in a liquid such as water and sprayed onto the surface of the support at a high speed to roughen the surface of the support, and the surface roughness is determined by the spray pressure. , Speed, amount of abrasive, type, shape, size, hardness, specific gravity, suspension temperature and the like. The dry honing treatment is a method of roughening the surface of the support by spraying an abrasive on the surface of the support with air at a high speed, and the surface roughness can be controlled in the same manner as the wet honing treatment. As an abrasive | polishing agent used for a honing process, particles, such as a silicon carbide, an alumina, iron, a glass bead, are mentioned.

  Between the support and the photosensitive layer or an intermediate layer described later, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering of laser light or the like and covering the scratches on the support.

  The conductive layer can be formed by dispersing conductive particles such as carbon black, metal particles, and metal oxide particles in a binder resin. Suitable metal oxide particles include zinc oxide and titanium oxide particles. Also, barium sulfate particles can be used as the conductive particles. A conductive layer may be provided on the conductive particles.

  The volume resistivity of the conductive particles is preferably in the range of 0.1 to 1000 Ω · cm, and more preferably in the range of 1 to 1000 Ω · cm. The volume resistivity is a value obtained by measurement using a resistance measuring apparatus Loresta AP manufactured by Mitsubishi Oil Chemical Co., Ltd., with a measurement sample that is hardened with a pressure of 49 MPa and formed into a coin shape. The average particle diameter of the conductive particles is preferably in the range of 0.05 to 1.0 μm, more preferably in the range of 0.07 to 0.7 μm (this average particle diameter is a value measured by a centrifugal sedimentation method). .) The ratio of the conductive particles in the conductive layer is preferably in the range of 1.0 to 90% by mass and more preferably in the range of 5.0 to 80% by mass with respect to the total mass of the conductive layer.

  Examples of the binder resin used for the conductive layer include phenol resin, polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyamic acid resin, polyvinyl acetal resin, epoxy resin, acrylic resin, melamine resin, and polyester resin. Can be mentioned. These resins can be used alone or as a mixture of two or more thereof, or a copolymer thereof. These resins / mixtures / copolymers have good adhesion to the support, improve the dispersibility of the conductive particles, and have good solvent resistance after film formation. Among these, a phenol resin, a polyurethane resin, and a polyamic acid resin are preferable.

  The thickness of the conductive layer is preferably from 0.1 to 30 μm, more preferably from 0.5 to 20 μm.

The volume resistivity of the conductive layer is preferably 10 ¹³ Ω · cm or less, and more preferably in the range of 10 ⁵ or more and 10 ¹² Ω · cm or less. The volume resistivity is determined by forming a film on the aluminum plate with the same material as the conductive layer to be measured, forming a gold thin film on the film, and flowing between the electrodes of the aluminum plate and the gold thin film. It is a value obtained by measuring the value with a pA meter.

  In addition, the conductive layer may contain fluorine or antimony as necessary, and a leveling agent may be added to improve the surface property of the conductive layer.

  An intermediate layer (also referred to as an undercoat layer or an adhesive layer) having a barrier function or an adhesive function may be provided between the support or the conductive layer and the photosensitive layer. The intermediate layer is formed for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown.

  The intermediate layer is acrylic resin, allyl resin, alkyd resin, ethyl cellulose resin, ethylene-acrylic acid copolymer, epoxy resin, casein resin, silicone resin, gelatin resin, polyamide, phenol resin, butyral resin, polyacrylate resin, polyacetal resin, polyamide Imide resin, polyamide resin, polyallyl ether resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl alcohol resin, polybutadiene resin, polypropylene resin, urea resin, etc. It can be formed using a material such as aluminum.

  The thickness of the intermediate layer is preferably from 0.05 to 5 μm, and more preferably from 0.3 to 1 μm.

  When the photosensitive layer of the present invention has a layer structure of a function-separated type photosensitive layer, a charge generation layer and a charge transport layer are laminated. However, the order of film formation is not particularly limited.

  In the present invention, a general material can be used as the charge generation material. Various materials known in the art can be used as the charge generating material, and examples thereof include selenium-tellurium, pyrylium, thiapyrylium dyes, compounds having various central metals, and crystal systems. , Phthalocyanine compounds having crystal types such as β, γ, ε, and X type, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, Examples include quinocyanine and A-Si (amorphous silicon).

  In addition to the charge generation material, a binder resin can also be used. Specific examples of the binder resin include polyester, polyurethane, polyacrylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, phenol resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, polyamide. -Imido, polysulfone, polyallyl ether, polyacetal, butyral resin, benzal resin and the like.

  When the charge generation layer contains a binder resin, the ratio of the charge generation material to the binder resin is preferably 0.1 to 100% in terms of the mass ratio of the charge generation material to the total amount of the binder resin and the charge generation material. Preferably, it is 10 to 80%.

  The thickness of the charge generation layer is preferably from 0.001 to 6 μm, more preferably from 0.01 to 2 μm. The mass ratio of the charge generation material contained in the entire charge generation layer is preferably 10 or more and 100% or less, more preferably 50 or more and 100% or less.

  Examples of charge transport materials include pyrene compounds, N-alkylcarbazole compounds, hydrazone compounds, N, N-dialkylaniline compounds, diphenylamine compounds, triphenylamine compounds, triphenylmethane compounds, pyrazoline compounds, styryl compounds, stilbene compounds, etc. Is mentioned.

  In addition to the charge transport material, a binder resin can also be used. Specific examples of the binder resin include polyester, polyurethane, polyacrylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, and the like.

  When the charge transport layer is used on the outermost surface, a resin or monomer that cures or polymerizes by using heat, light, radiation irradiation, or the like, or these resins or monomers having a hole transport function can be used for the charge transport layer. .

  As a compound that is polymerized or crosslinked and cured by irradiation with heat, light, or radiation, it can be crosslinked via a hydrolysis or condensation reaction by heat, such as phenol, epoxy, alkoxysilane, etc. by irradiation with heat, light, or radiation. Although it will not be limited if it is a compound which can generate | occur | produce active sites, such as a radical, and can superpose | polymerize or bridge | crosslink, the compound which has a chain polymerizable functional group is generally mentioned in the point of reactivity or intensity | strength. Among them, a compound having an unsaturated polymerizable functional group in the molecule is preferable in terms of high reactivity, fast reaction rate, versatility of materials, etc., and an acryloyloxy group as the unsaturated polymerizable functional group, A methacryloyloxy group, a styrene group and the like are particularly preferable. These compounds are not limited to monomers, oligomers, macromers, and polymers, and may be appropriately selected or used in combination. In addition, in the case of using a compound having charge transporting property, preferably hole transporting property, and being polymerized or crosslinked and cured by irradiation with heat, light or radiation, a charge transport layer can be formed by itself. In particular, a surface layer having excellent electrophotographic characteristics and high strength can be formed. In addition, the surface layer according to the present invention may further include a charge transporting material and a compound that is polymerized or crosslinked and cured by irradiation with heat, light, or radiation that does not have charge transporting properties.

  The compound having charge transporting property and polymerized or crosslinked and cured by irradiation with heat, light or radiation is, for example, a known hole transporting compound having an unsaturated polymerizable functional group or a known hole transporting compound. A compound in which an unsaturated polymerizable functional group is partially added is used. Examples of known hole transporting compounds include hydrazone compounds, pyrazoline compounds, triphenylamine compounds, benzidine compounds, stilbene compounds and the like, but any compounds can be used as long as they are hole transporting compounds. Furthermore, in the present invention, in order to sufficiently ensure the hardness of the electrophotographic photoreceptor surface layer, the compound having an unsaturated polymerizable functional group is a compound having a plurality of unsaturated polymerizable functional groups in one molecule. Is preferred.

  When the charge transport layer contains a binder resin, the ratio of the charge transport material to the binder resin is preferably 0.1 to 100% by mass ratio of the charge transport material to the total amount of the binder resin and the charge transport material, Preferably, it is 10 to 80%.

  The thickness of the charge transport layer is preferably from 5 to 40 μm, more preferably from 10 to 30 μm. If this thickness is less than 5 μm, the charging ability cannot be maintained, and if it is greater than 40 μm, the residual potential becomes too high.

  The amount of the charge transport material contained in the charge transport layer is preferably 20 or more and 100% or less, and more preferably 30 or more and 90% or less in mass ratio.

  When the photosensitive layer is used as a single layer, the charge generation material and the charge transport material are contained in the same layer. Specific examples of the charge generation material and the charge transport material are the same as in the case of the above-described laminated photoreceptor. Similarly, a resin or monomer that cures or polymerizes using radiation, or a resin or monomer having a hole transport function may be used.

  The thickness of the single photosensitive layer is preferably from 8 to 40 μm, more preferably from 12 to 30 μm. The single-layer photosensitive layer preferably has a photoconductive material such as a charge generation material or a charge transport material in the range of 20 to 100% by mass, and more preferably 30 to 90% by mass.

When providing a protective layer on the outermost surface, the film thickness is preferably 0.01 to 10 μm, more preferably 0.1 to 7 μm. Resins that cure or polymerize using radiation, or monomers, or these resins or monomers having a hole transport function can be used. Furthermore, you may contain electroconductive materials, such as a metal or its oxide, nitride, salt, an alloy, or carbon, in a protective layer. Examples of such metal species include iron, copper, gold, silver, lead, zinc, nickel, tin, aluminum, titanium, antimony, and indium. Specifically, ITO, TiO ₂ , ZnO, SnO ₂ Al ₂ O ₃ or the like can be used. The conductive material is dispersed in the protective layer in the form of fine particles, and the particle diameter is preferably 0.001 to 5 μm, more preferably 0.01 to 1 μm. Is preferably 1 or more and 70% by mass or less, more preferably 5 or more and 50% by mass or less. A titanium coupling agent, a silane coupling agent, various surface activities, and the like may be used as the dispersant.

  Various additives such as an antioxidant and a photodegradation inhibitor may be used for each layer constituting the photosensitive layer. Further, the surface layer may contain various fluorine compounds, silane compounds, metal oxides or the like or fine particles thereof for the purpose of improving the lubricity and water repellency. A dispersant or a surfactant may be used for the purpose of improving these dispersibility. The content of these additives in the surface layer is preferably 1 to 70% by mass, more preferably 5 to 50% by mass.

  As a method for producing the electrophotographic photoreceptor of the present invention, methods such as vapor deposition and coating are used, and among these, the coating method is most preferable. The coating method can form films having various compositions in a wide range from a thin film to a thick film. Specifically, it is applied by a bar coater, knife coater, dip coating, spray coating, beam coating, electrostatic coating, roll coater, attritor, powder coating or the like.

  Next, a method for forming the surface layer by polymerizing or crosslinking and curing the compound will be described. In the present invention, the formation of the surface layer uses a compound that is polymerized or crosslinked and cured by irradiation with heat, light, or radiation. However, in the case of curing or crosslinking reaction with heat or light, a reaction initiator is required, but radiation is used. In the case of irradiation, since no starting material is required, it is particularly preferable in terms of electrophotographic characteristics.

  The radiation irradiation will be described. Examples of the radiation in the present invention include an electron beam and a γ-ray as in the disclosure of Patent Document 1, and an electron beam is preferable from various points such as the size, safety, cost, and versatility of the apparatus. In the case of electron beam irradiation, examples of the accelerator include a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type.

When the electrophotographic photoreceptor according to the present invention is formed using electron beam irradiation, the acceleration voltage of the electron beam is preferably 300 KV or less, and 150 KV or less, in order to sufficiently develop the electrical characteristics and durability of the electrophotographic photoreceptor. Is more preferable. The absorbed dose of the electron beam is preferably 1 or more and 100 Mrad or less (1 × 10 ⁴ or more and 1 MGy or less), and more preferably 1 or more and 50 Mrad or less (5 × 10 ⁵ Gy). When the acceleration voltage exceeds 300 KV or the dose exceeds 100 Mrad (1 MGy), the electrophotographic photosensitive member tends to deteriorate. In addition, the method for forming an electrophotographic photoreceptor using electron beam irradiation according to the present invention may further include a heating step in order to increase the efficiency of polymerization and crosslinking.

  A preferable surface shape of the electrophotographic photosensitive member according to the present invention includes a shape in which grooves formed in the circumferential direction and a flat portion are combined or a dimple shape.

  In the shape in which the groove and the flat portion are combined, the width of the groove is preferably 0.5 to 40 μm, and the groove number density per unit length of 1000 μm is preferably 20 to 1000. When this width exceeds 40 μm, a white streak image tends to be generated on the halftone image. Further, if the groove number density is less than 20, problems occur in the pressure contact portion of the electrophotographic photosensitive member, specifically, contamination of the charging unit, deterioration of the charging property of the developer in the developing unit, scratches on the transfer unit, etc. Occurs. Further, if the groove density exceeds 1000, the character reproducibility tends to be inferior.

  Note that the groove width, flat portion width, and groove number density on the surface of the electrophotographic photosensitive member were measured using a non-contact three-dimensional surface measuring machine (trade name: Micromap 557N, manufactured by Ryoka System Co., Ltd.). It was. Attach a five-fold two-beam interference objective lens to the optical microscope section of the micromap, fix the photoconductor under the lens, and vertically scan the interference image using a CCD camera in the Wave mode to obtain a three-dimensional image. obtain. The range of the obtained image is 1.6 mm × 1.2 mm. The image thus obtained is analyzed, and the number of grooves and the groove width per unit length of 1000 μm are obtained as data. Based on this data, the above-described groove width and number of grooves can be analyzed. In the present invention, grooves having a width of 0.5 μm or more were counted, and at three locations in the electrophotographic bus direction, 12 locations were measured in the circumferential direction at each location. Further, regarding the groove width and the number of grooves, in addition to the micromap, commercially available laser microscopes (ultra-deep shape measurement microscopes VK-8550, VK-9000 (manufactured by Keyence Corporation), scanning confocal laser microscope OLS3000 (Olympus ( Co., Ltd.) Real Color Confocal Microscope Oplitex C130 (Lasertec Co., Ltd.)), Digital Microscope VHX-100, VH-8000 (Keyence Co., Ltd.)) etc. Based on the image processing software (for example, WinROOF (manufactured by Mitani Shoji Co., Ltd.)), the groove width and the number of grooves can be obtained, and a three-dimensional non-contact shape measuring device (NewView 5032 (manufactured by Zygo Co., Ltd.)) It is possible to measure in the same manner as the micromap.

  Examples of the roughening method for obtaining the shape of the surface of the electrophotographic photosensitive member include a method of physically polishing the surface of the electrophotographic photosensitive member. A method of applying a photosensitive layer / protective layer to maintain the surface shape of the support up to the surface of the photosensitive member, or a fluid state that occurs before the photosensitive layer / protective layer is applied and dried or cured. Moreover, the method of forming the above-mentioned surface shape with a roughening means is also mentioned. As an example of the roughening means, there is a method of polishing the surface of the photoreceptor by pressing the electrophotographic photoreceptor against a polishing sheet in which abrasive grains are dispersed in a binder resin while rotating the electrophotographic photoreceptor. This polishing is basically performed by constantly pressing an untreated polishing sheet against the surface of the photoconductor to roughen the surface of the photoconductor. Since this polishing sheet is basically insulative, it is preferable to use a sheet in which a portion in contact with the sheet is grounded or a conductive sheet. The shape of the photoreceptor surface in the present invention is, for example, when a polishing sheet is used as a roughening means, the polishing sheet feed speed, the pressing pressure between the photoreceptor and the polishing sheet, the grain size and shape of the abrasive grains, and the polishing sheet What is necessary is just to adjust by selecting suitably the count of the abrasive grain to disperse | distribute, the binder resin thickness of a polishing sheet, a base material thickness, etc.

On the other hand, the electrophotographic photoreceptor of the present invention preferably has a dimple shape on the surface of the electrophotographic photoreceptor in order to achieve the object of the present invention. In the present invention, the dimple shape means a fine uneven shape. In particular, the dimple shape is preferably a surface processed so as to have more dents than the reference surface before roughening. The number of dimples suitable for the photoreceptor of the present invention is preferably 5 or more and 40 or less per 10,000 μm ² . The area ratio of dimples is preferably 3 to 50%. Even if the number and area ratio of these dimples exceed the upper limit or less than the lower limit, it is difficult to obtain a roughened effect.

  The method for forming the dimple shape is preferably a dry blast method or a wet honing method. Further, the dry blasting method is more preferable because the electrophotographic photosensitive member sensitive to humidity conditions can be roughened without contacting with a solvent such as water. As a blasting method, there are a method in which compressed air is used as power, a method in which a motor is used as power, etc., but the roughening of the photoconductor can be precisely controlled and the facility is simple. Thus, a method using compressed air is preferable. Examples of the material of the abrasive used for blasting include ceramic systems such as aluminum oxide, zirconia, silicon carbide, and glass, metal systems such as stainless steel, iron, and zinc, and resin systems such as polyamide, polycarbonate, epoxy, and polyester. In particular, glass, aluminum oxide, and zirconia are preferable from the viewpoint of roughening efficiency and cost. The shape of the photoreceptor surface in the present invention may be adjusted by appropriately selecting the pressure of compressed air, the type of abrasive, etc., for example, in the case of a method of jetting using compressed air. The surface shape or roughening of the present invention is independent of the surface shape of the conductive substrate underlying the photoreceptor. In particular, when the method for forming the organic photosensitive layer is a dip coating method, the surface on which the film is formed is often very smooth, and even if the base is roughened, the surface shape is not reflected. Further, when the dimple-like surface shape of the present invention is formed by subjecting it to mechanical surface roughening, the surface of the photoconductor is roughened from the outermost surface layer after the photoconductor is finally formed to the layer to be used. Is preferred.

  Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
60 parts by mass of titanium oxide powder (trade name: Kronos ECT-62, manufactured by Titanium Industry Co., Ltd.) having a coating film of tin oxide doped with antimony, titanium oxide powder (trade name: titone SR-1T, 堺Chemical Co., Ltd.) 60 parts by mass, resol type phenol resin (trade name: Phenolite J-325, Dainippon Ink & Chemicals, Inc., solid content 70%) 70 parts by mass, 2-methoxy-1-propanol A solution composed of 50 parts by mass and 50 parts by mass of methanol was dispersed with a ball mill for about 20 hours. The average particle size of the filler in this dispersion was 0.25 μm.

  The dispersion prepared in this manner was applied by dipping onto a 31 mmφ × 370 mm long aluminum cylinder, dried and cured for 30 minutes in a hot air drier adjusted to 150 ° C., and a conductive film having a film thickness of 15 μm. A layer was formed.

  Next, 10 parts by mass of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) and 30 parts by mass of methoxymethylated nylon resin (trade name: Toresin EF30T, manufactured by Teikoku Chemical Industry Co., Ltd.) were added to methanol 500. A solution dissolved in a mixed solution of parts by mass and 250 parts by mass of butanol is dip-coated on the above-mentioned conductive layer, put into a hot air dryer adjusted to 100 ° C. for 10 minutes, and dried by heating to obtain a film thickness of 0. A subbing layer of 5 μm was formed.

  Next, 4 parts by mass of a hydroxygallium phthalocyanine pigment having strong peaks at 7.4 ° and 28.2 ° with a Bragg angle 2θ ± 0.2 ° in a CuKa characteristic X-ray diffraction spectrum, a polyvinyl butyral resin (trade name: ESREC BX) -1, manufactured by Sekisui Chemical Co., Ltd.) and 90 parts by mass of cyclohexanone were dispersed in a sand mill for 10 hours using glass beads with a diameter of 1 mm, and then charged with 110 parts by mass of ethyl acetate. A layer coating solution was prepared. This coating solution was dip-coated on the undercoat layer described above, placed in a hot air dryer adjusted to 100 ° C. for 10 minutes, and dried by heating to form a charge generation layer having a thickness of 0.2 μm.

  Next, 35 parts by mass of a triarylamine compound represented by the following structural formula

及びビスフェノールＺ型ポリカーボネート樹脂（商品名：ユーピロンＺ４００、三菱エンジニアリングプラスティックス（株）製）５０質量部を、モノクロロベンゼン３２０質量部及びジメトキシメタン５０質量部に溶解して調製した電荷輸送層用塗工液を、上述の電荷発生層上に浸漬塗布し、１００℃に調整された熱風乾燥機中に６０分間投入し加熱乾燥して、膜厚１５μｍの第一の電荷輸送層を形成した。

And bisphenol Z-type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) dissolved in 320 parts by mass of monochlorobenzene and 50 parts by mass of dimethoxymethane, and applied for a charge transport layer coating The solution was dip-coated on the above-described charge generation layer, placed in a hot air dryer adjusted to 100 ° C. for 60 minutes, and dried by heating to form a first charge transport layer having a thickness of 15 μm.

Next, 0.1 part by mass of a fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 1,1,2,2,3,3,4-heptafluorocyclopentane ( Product name: Zeolola H, manufactured by Nippon Zeon Co., Ltd.) 35 parts by mass and 1-propanol 35 parts by mass, and then dissolved in tetrafluoroethylene resin powder (trade name: Lubron L-2, Daikin) 2 parts by mass of Kogyo Kogyo Co., Ltd. were added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 59 N / mm ^{2 with} a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA). . This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion. Thereafter, 25 parts by mass of a hole transporting compound represented by the following structural formula

を上述の潤滑剤分散液に加え、ＰＴＦＥ製の５μｍメンブレンフィルターで加圧ろ過を行い、硬化型表面層としての第二の電荷輸送層用塗工液を調製した。この塗工液を用いて前記第一の電荷輸送層上に硬化型表面層として第二の電荷輸送層を浸漬塗布法により塗工した。その後、窒素中において加速電圧１２０ｋＶ、線量１．５Ｍｒａｄ（１．５×１０^４Ｇｙ）の条件で電子線を照射した。引き続いて感光体の温度が１２０℃になる条件で９０秒間加熱処理を行った。このときの酸素濃度は１０ｐｐｍであった。更に、感光体を大気中で１００℃に調整された熱風乾燥機中で２０分間加熱処理を行って、膜厚５μｍの硬化型表面層を形成した。

Was added to the above-mentioned lubricant dispersion and subjected to pressure filtration with a PTFE 5 μm membrane filter to prepare a second charge transport layer coating solution as a curable surface layer. Using this coating solution, a second charge transport layer was applied as a curable surface layer on the first charge transport layer by a dip coating method. Thereafter, an electron beam was irradiated in nitrogen under the conditions of an acceleration voltage of 120 kV and a dose of 1.5 Mrad (1.5 × 10 ⁴ Gy). Subsequently, a heat treatment was performed for 90 seconds under the condition that the temperature of the photoconductor was 120 ° C. The oxygen concentration at this time was 10 ppm. Further, the photoconductor was subjected to a heat treatment for 20 minutes in a hot air dryer adjusted to 100 ° C. in the atmosphere to form a curable surface layer having a thickness of 5 μm.

  A part of the obtained photoreceptor was allowed to stand in an environment of 25 ° C./50% for 24 hours, and then the universal hardness value (HU) and elastic deformation rate were measured with a microhardness measuring device Fischerscope H100V (manufactured by Fischer). And measured.

Next, using an abrasive sheet (trade name: C-3000, manufactured by Fuji Photo Film Co., Ltd.), abrasive grains: Si-C (average particle diameter: 9 μm), substrate: polyester film (thickness: 75 μm), A nip pressure of 0.05 N / mm ² between the photosensitive member and the polishing sheet, a photosensitive member rotation speed of 20 rpm, a polishing sheet feed speed of 2 mm / second, while rotating the polishing sheet and the electrophotographic photosensitive member in the forward direction for 300 seconds, Roughening was performed.

  For the surface roughness, a contact-type surface roughness measuring machine (trade name: Surfcorder SE3500, manufactured by Kosaka Laboratory Ltd.) was used. Detector: R2 μm, 0.7 mN diamond needle, filter: 2CR, cutoff value: 0.8 mm, measurement length: 2.5 mm, feed rate: 0.1 mm, maximum described in JIS-B0601-2001 Data of height Rz and ten-point average surface roughness Rzjis were obtained. Measurements were made at 12 points in total, 3 points in the thrust direction of the photoreceptor and 4 points in the circumferential direction in each thrust direction, and the average value was obtained. The surface shape was measured using a non-contact three-dimensional surface measuring machine (trade name: Micromap 557N, manufactured by Ryoka System Co., Ltd.).

  The obtained electrophotographic photosensitive member was allowed to stand in an environment of 30 ° C./80% for 24 hours, and then evaluated using a copying machine (trade name: IRC3200, manufactured by Canon Inc.) in an environment of 30 ° C./80%. .

  First, a grid image was output to evaluate the image flow. Next, 10,000 sheets, 50,000 sheets, and 100,000 sheets of continuous paper passing durability test were performed, and a lattice image and a halftone image were output to confirm the presence / absence of image flow, image defects, and the surface state of the photoreceptor.

  The evaluation results are shown in Table 1. As shown in Table 1, the electrophotographic photosensitive member of the present invention has good initial electrophotographic characteristics, has a small amount of shaving in durability, and does not generate image flow even under high temperature and high humidity, and has excellent durability. It was found to show performance.

(Example 2)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the nip pressure between the photoreceptor and the polishing sheet was 0.01 N / mm ² and the roughening time was 60 seconds. did. The evaluation results are shown in Table 1.

(Example 3)
In Example 1, an electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the nip pressure between the photosensitive member and the polishing sheet was 0.02 N / mm ² and the roughening time was 15 minutes. did. The evaluation results are shown in Table 1.

Example 4
Example 1 is the same as Example 1 except that a polishing sheet (trade name: AX-1500 (manufactured by Fuji Photo Film Co., Ltd.) is used and the nip pressure between the photoreceptor and the polishing sheet is 0.01 N / mm ^2. Similarly, an electrophotographic photosensitive member was prepared and evaluated, and the evaluation results are shown in Table 1.

(Example 5)
In Example 1, a photoconductor was prepared and evaluated in the same manner as in Example 1 except that the roughening treatment was changed to the following method.

The surface roughening treatment of the outermost layer of the photoreceptor was performed as follows. Dry blasting equipment (manufactured by Fuji Seiki Co., Ltd.), abrasive abrasive grains are spherical glass beads having an average particle size of 30 μm (trade name: UB-01L, manufactured by Union Co., Ltd.), and air spraying pressure 0.13 N / mm ^2. Roughening was performed under the conditions of blast gun moving speed of 430 mm / min, photosensitive member rotation speed: 288 rpm, distance between the blast gun discharge port and the photosensitive member: 100 mm, and the number of times of blasting: one way × 1 time.

  Further, the abrasive material remaining on the surface of the photoreceptor was removed by blowing compressed air. The evaluation results are shown in Table 1.

(Example 6)
In Example 5, the surface was roughened at an air blowing pressure of 0.20 N / mm ² . Otherwise, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 4. The evaluation results are shown in Table 1.

(Example 7)
In Example 5, the surface was roughened at an air blowing pressure of 0.30 N / mm ² . Otherwise, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 4. The evaluation results are shown in Table 1.

(Example 8)
Example 1 in the coating liquid for the second charge transport layer of Example 1 except that the fluorine atom-containing resin in the lubricant dispersion was 0.5 part by mass and the tetrafluoroethylene resin powder was 15 parts by mass. An electrophotographic photoreceptor was prepared and evaluated in the same manner as described above. The evaluation results are shown in Table 1.

Example 9
In Example 8, a photoconductor was prepared and evaluated in the same manner as in Example 8 except that the roughening treatment was changed to the method of Example 5 and the air spraying pressure was changed to 0.25 N / mm ² . The evaluation results are shown in Table 1.

(Example 10)
In Example 1, the amount of the hole transporting compound having the structure represented by Compound 2 used in the coating solution for the second charge transport layer was changed from 25 parts to 15 parts, and the coating solution for the second charge transport layer was used. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that 10 parts of an acrylic monomer having a structure represented by the following structural formula was used. The evaluation results are shown in Table 1.

(Example 11)
In Example 10, a photoconductor was prepared and evaluated in the same manner as in Example 10 except that the roughening treatment was changed to the method of Example 5 and the air blowing pressure was 0.40 N / mm ² . The evaluation results are shown in Table 1.

(Comparative Example 1)
When the electrophotographic photosensitive member produced in Example 1 was not roughened and evaluated in the same manner as in Example 1, an image flow occurred. The evaluation results are shown in Table 1.

(Comparative Example 2)
In Example 1, the developer charge amount control means of the evaluator was removed and the evaluation was performed in the same manner as in Example 1. As a result, image flow occurred after durability. The evaluation results are shown in Table 1.

(Comparative Example 3)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the surface was roughened with an abrasive sheet (trade name: C-1000, manufactured by Fuji Photo Film Co., Ltd.). White streaks occurred on the halftone image after 50,000 sheets were used. The results are shown in Table 1.

(Comparative Example 4)
In Example 5, the surface was roughened at an air spray pressure of 0.05 N / mm ² . Otherwise, an electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1. As a result, image bleed occurred. The evaluation results are shown in Table 1.

(Comparative Example 5)
In Example 9, the surface was roughened at an air blowing pressure of 0.35 N / mm ² . Other than that, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 9, and white streaks were generated on the halftone image after the endurance of 100,000 sheets. The results are shown in Table 1.

(Comparative Example 6)
In Example 1, the film thickness of the first charge transport layer was 20 μm, the second charge transport layer was not provided, and the photoconductor surface was not roughened. A body was created and evaluated. When about 30,000 sheets were used, developer fusion to the surface of the photoconductor occurred. The evaluation results are shown in Table 1.

It is a schematic diagram showing an example of an image forming apparatus using the image forming method of the present invention. 1 is a schematic diagram illustrating an example of an image forming apparatus that executes an image forming method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Charging means 3 Exposure means 4 Developing means 5 Transfer means P Transfer material 7 Developer charge amount control means 8 Residual developer uniformizing means

Claims (5)

An electrophotographic photoreceptor;
Charging means for charging the electrophotographic photosensitive member;
Information writing means for forming an electrostatic latent image on a charged electrophotographic photosensitive member;
Developing means for supplying a developer to visualize the electrostatic latent image;
Means for transferring the visualized developer image to a transfer material;
Developer charge amount control means for charging the developer remaining on the electrophotographic photosensitive member after the transfer step;
An electrophotographic apparatus comprising:
The developing means collects toner remaining on the electrophotographic photosensitive member after transfer,
There is no cleaning means for collecting and storing the toner remaining on the electrophotographic photosensitive member after transfer between the transfer means and the charging means and between the charging means and the developing means,
The electrophotographic photoreceptor is
An electrophotographic photosensitive member having a conductive support and a photosensitive layer laminated on the conductive support,
The elastic deformation rate at the surface hardness of the electrophotographic photoreceptor is 45% or more and 65% or less,
The initial surface roughness: Rzjis (ten-point average surface roughness) of the electrophotographic photosensitive member is 0.3 μm or more and 1.3 μm or less, and the initial maximum height Rz is less than 2.0 μm. An electrophotographic apparatus.   The electrophotographic apparatus according to claim 1, wherein a surface layer of the electrophotographic photosensitive member has a curable resin. The electrophotographic apparatus according to claim 1, wherein a universal hardness (HU) of a surface layer of the electrophotographic photosensitive member is 150 N / mm ² or more and 220 N / mm ² or less.   4. The electrophotographic apparatus according to claim 1, wherein a surface shape of the electrophotographic photosensitive member includes a groove and a flat portion that are continuously formed in a circumferential direction. 5.   The electrophotographic apparatus according to any one of claims 1 to 3, wherein a surface shape of the electrophotographic photosensitive member has dimple-like irregularities.

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