JP4214857B2 - Electrophotographic photoreceptor and method for manufacturing the same, image forming apparatus, image forming method, and process cartridge - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member used for electrophotographic image formation such as charging, exposure, development, and transfer, a manufacturing method thereof, an image forming apparatus, an image forming method, and a process cartridge.

  An electrophotographic image forming method is generally performed as follows using an image forming apparatus. That is, first, an electrostatic latent image is formed on an electrophotographic photoreceptor (hereinafter sometimes referred to as “photoreceptor”) through a charging step and an exposure step. Next, in the development step, the electrostatic latent image is developed with a developer containing toner, and then, through a transfer step, a fixing step, and the like, the toner is transferred onto the transfer medium to form an image. After the toner has been transferred, the photoreceptor is subjected to a series of steps from the charging step again in the next image forming cycle after the residual potential on the surface is removed by the discharging step. In such an image forming method, even after the transfer step, a part of the toner remains attached to the surface of the photoreceptor, and thus the remaining toner is collected by the cleaning step.

  However, for example, in various processes, the toner is pulverized due to mechanical influences such as shearing force, so that when the particle size is reduced, the adhesion to the photoreceptor is increased. There arises a problem that the toner cannot be sufficiently removed from the photoreceptor.

In order to solve the above-described problems, for example, Patent Document 1 proposes a toner composed of colored particles and external additives obtained by fusing at least resin particles and coloring agent particles in an aqueous medium.
JP 2000-250259 A

  However, even if the conventional toner proposed in Patent Document 1 is used, it cannot be said that the toner on the photoreceptor can be sufficiently removed by the cleaning process.

  That is, in the case of the conventional toner, the particle shape is uniform, but due to the smoothness of the surface, even if it contacts the blade of the cleaning device, it is difficult to peel off from the photoreceptor. Therefore, the toner remains on the surface of the photoreceptor to some extent even after the cleaning process.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an electrophotographic photosensitive member that does not leave toner on the surface of the photosensitive member after the cleaning step in the image forming method, a manufacturing method thereof, and an image forming apparatus. An object of the present invention is to provide an image forming method and a process cartridge.

  The inventors of the present invention have made extensive studies to achieve the above object from the viewpoint of reducing the frictional force between the photoconductor and the toner adhering to the surface of the photoconductor. As a result, the photoconductor satisfies specific conditions. It has been found that the above-mentioned problems can be solved by containing the specific resin to be completed, and the present invention has been completed.

That is, the electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which a photosensitive layer is formed on a conductive substrate, and the photosensitive layer is located at a position farthest from the conductive substrate, and is a tetrafluoroethylene resin. A surface layer containing particles and a fluorine-based graft polymer, the average primary particle diameter of the tetrafluoroethylene resin particles is 0.1 to 0.3 μm, and the primary particles and particle diameters of the tetrafluoroethylene resin particles The content ratio of secondary particles less than 1 μm is 80% or more based on the total number of primary particles and secondary particles of the tetrafluoroethylene resin particles.

  Here, the “primary particles” of the fluororesin particles are the smallest unit particles that exist without breaking the bonds between the molecules of the fluororesin, and the “secondary particles” are a plurality of primary particles. A particle formed by aggregation. In the present specification, the “total number of primary particles and secondary particles” refers to the total number of the above-mentioned “primary particles” and “secondary particles”, but the number of “primary particles”. Does not count the primary particles that make up the secondary particles.

  Further, the number of “primary particles” and the number of “secondary particles” are measured as follows. That is, using a microscope such as a TEM (transmission electron microscope), the surface layer of the photoreceptor is photographed to obtain a photograph thereof. Then, the number of “primary particles” and “secondary particles” observed in the surface layer photograph is counted by visual observation.

  The particle diameter of each primary particle or secondary particle of the fluororesin particles is also measured using a surface layer photograph of the photoreceptor taken with a microscope, as with the above number.

  Thus, the surface layer of the photoreceptor in direct contact with the toner contains fluorine resin particles and fluorine graft polymer, and contains primary particles of the fluorine resin particles and secondary particles having a particle diameter of less than 1 μm. While the ratio is 80% or more with respect to the total number of primary particles and secondary particles of the fluororesin particles, the frictional force between the toner and the blade of the cleaning device does not change, It is considered that the frictional force between the surface layer and the toner attached to the surface layer is reduced.

  Therefore, even when the cleaning device provided in the conventional image forming apparatus is used, the toner is sufficiently removed from the surface layer of the photoreceptor by the blade of the cleaning device. In addition, when the toner is obtained by emulsion polymerization or described in Patent Document 1, the frictional force between the surface layer of the photosensitive layer and the toner is reduced. Is sufficiently removed from the surface layer of the photoreceptor.

  Further, when the toner is produced by a kneading and pulverizing method, the toner is pulverized relatively easily and finely divided at the time of image formation. If the electrophotographic photosensitive member of the present invention is used, the toner is a photosensitive member. Remaining in the surface layer is sufficiently suppressed. Therefore, even when a two-component developer containing the toner and the carrier is used as the developer, the finely divided toner is fused to the carrier or the developing sleeve and the charging deterioration of the developer is accelerated. The phenomenon seen in the past is less likely to occur.

  Even when a one-component developer containing a magnetic toner or a non-magnetic toner is used as a developer, the adhesion of the toner becomes stronger due to the refinement of the toner. Therefore, it is difficult to cause the phenomenon that has been seen so far, such that the image quality is lowered.

  In the electrophotographic photoreceptor of the present invention, the average primary particle diameter of the fluorine resin particles is preferably 0.1 to 0.3 μm. When such fluorine resin particles are used, the dispersibility of the fluorine resin particles in the surface layer of the photoreceptor is improved, so that the frictional force between the toner and the surface layer can be further reduced, and it is easy. The toner can be removed.

The method for producing an electrophotographic photosensitive member of the present invention is a method for producing an electrophotographic photosensitive member, wherein a photosensitive layer comprising a plurality of layers including a surface layer provided at a position furthest from the conductive substrate is formed on a conductive substrate. A mixing step for obtaining a mixture of at least tetrafluoroethylene resin particles, a fluorine-based graft polymer, and an organic solvent, and a high-pressure homogenizer that sets the pressure to 300 kg / cm ² or more and less than 700 kg / cm ² . , By treating the mixture twice or more to obtain a dispersion in which tetrafluoroethylene resin particles are dispersed, and forming a surface layer of the photosensitive layer by applying the dispersion and drying a step seen containing an average primary particle diameter of tetrafluoroethylene resin particles contained in the surface layer is 0.1 to 0.3 [mu] m, the tetrafluoroethylene resin particles primary particles及The content ratio of secondary particles having a particle diameter of less than 1 μm is 80% or more based on the total number of primary particles and secondary particles of the tetrafluoroethylene resin particles .

  By adopting such a method for producing an electrophotographic photoreceptor, the above-described electrophotographic photoreceptor can be obtained efficiently and reliably, so that the toner adhering to the surface layer of the photoreceptor can be sufficiently removed. It becomes possible.

  An image forming apparatus of the present invention includes the above-described electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, an exposure device that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, and A developing device that develops the electrostatic latent image to form a toner image, a transfer device that transfers the toner image to a transfer target, and a cleaning device that removes toner remaining on the electrophotographic photosensitive member. Is. Since such an image forming apparatus includes the electrophotographic photosensitive member, toner can be sufficiently suppressed from remaining on the surface layer of the photosensitive member, and thus an image with high image quality (image quality) can be obtained. And the stability of the image quality can be improved.

  Further, it is preferable that the image forming apparatus further includes a toner conveying device (toner recycling device) for supplying the toner removed by the cleaning device to the developing device. In an image forming apparatus provided with a toner conveying device, normally, toner finely pulverized once through an image forming cycle is collected by a cleaning device, conveyed from there to a developing device, and reused. At the time of collection by the cleaning device, the toner is further pulverized by the action of the blade of the cleaning device and the photoconductor, so that the charging deterioration of the developer becomes more remarkable and the adhesion force of the toner to the photoconductor is increased. It becomes stronger and causes a problem that the transfer rate of the toner is lowered or the cleaning is poor.

  However, since the image forming apparatus according to the present invention includes the above-described electrophotographic photosensitive member, the toner is easily peeled and removed from the photosensitive member upon collection by the cleaning device. It is considered to be suppressed. Therefore, the problems as described above are unlikely to occur.

  The process cartridge of the present invention includes the above-described electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, an exposure device that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic device. From a developing device that develops a latent image to form a toner image, a cleaning device that removes toner remaining on the electrophotographic photosensitive member, and a toner conveying device that supplies the toner removed by the cleaning device to the developing device And at least one selected. By using such a process cartridge, a high-quality image can be obtained and the high-quality image can be stably maintained.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member that does not leave toner on the surface of the photosensitive member after the cleaning step in the image forming method, a manufacturing method thereof, an image forming apparatus, an image forming method, and a process cartridge.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

(Electrophotographic photoreceptor)
FIG. 1 is a cross-sectional view schematically showing a main part of a preferred embodiment of the electrophotographic photosensitive member of the present invention, in which the electrophotographic photosensitive member 1 is cut along the stacking direction of the substrate 2 and the photosensitive layer 3. is there. Each of the electrophotographic photoreceptors 1 shown in FIG. 1 is a function-separated type photoreceptor, and a charge generation layer 5 and a charge transport layer 6 are separately provided on the photosensitive layer 3 provided in each photoreceptor. More specifically, in the electrophotographic photoreceptor 1 shown in FIG. 1, the charge generation layer 5 and the charge transport layer 6 are laminated in this order on the conductive substrate 2 to constitute the photosensitive layer 3.

    The conductive substrate 2 is not particularly limited as long as it has conductivity. For example, a metal drum such as aluminum, copper, iron, zinc, or nickel can be used. Conductive treatment was carried out by depositing metals such as aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, and copper-indium on a polymer sheet, paper, plastic, or glass. Can be used in the form of a drum, sheet or plate.

  In addition, drums, sheets, and plates that are conductively processed by depositing conductive metal compounds such as indium oxide and tin oxide on polymer sheets, paper, plastics, or glass, or laminating metal foils. Can be used. In addition to this, carbon black, indium oxide, tin oxide-antimony oxide powder, metal powder, copper iodide, etc. are dispersed in a binder resin and applied onto a polymer sheet, paper, plastic, or glass. A drum-like, sheet-like or plate-like one subjected to conductive treatment can also be used.

  Here, when a metal pipe substrate is used as the conductive substrate 2, even if the surface remains as a raw tube, mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, wet honing or coloring are performed in advance. It is preferable that processing such as processing can be performed. By performing the surface treatment and roughening the surface of the base material, it is possible to prevent grain-like density spots due to interference light in the photosensitive body that may occur when a coherent light source such as a laser beam is used.

  The charge generation layer 5 is formed in a state where a charge generation material is dispersed in an appropriate binder resin. As the charge generation material, phthalocyanine pigments, quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, quinacridone pigments, and the like can be used. These charge generation materials can be used alone or in combination of two or more.

  Among these, phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine or titanyl phthalocyanine are preferable as the charge generation material from the viewpoint of obtaining an excellent image.

  More specifically, the Bragg angles (2θ ± 0.2 °) of the X-ray diffraction spectrum using CuKα rays are at least at the positions of 7.4 °, 16.6 °, 25.5 ° and 28.3 °. Chlorogallium phthalocyanine crystal having strong diffraction peak, Bragg angle (2θ ± 0.2 °) of X-ray diffraction spectrum using CuKα ray is at least 7.7 °, 9.3 °, 16.9 °, 17.5 A metal-free phthalocyanine crystal having strong diffraction peaks at positions of 2 °, 22.4 °, and 28.8 °, and a Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using CuKα rays is at least 7.5 °. , 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° using hydroxygallium phthalocyanine crystals having strong diffraction peaks or CuKα rays Bragg of X-ray diffraction spectrum (2θ ± 0.2 °) of at least 9.6 °, preferably by using the titanyl phthalocyanine crystal having strong diffraction peaks at 24.1 ° and 27.2 °.

  The binder resin in the charge generation layer 5 is not particularly limited, and a known material can be used. For example, preferred binder resins include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene copolymer resin, Acrylonitrile-butadiene copolymer, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, Phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, or poly-N-vinylcarbazole resin can be used. These binder resins can be used singly or in combination of two or more.

  In addition, the blending ratio of the charge generation material and the binder resin is preferably in the range of 10: 1 to 1:10.

  The layer thickness of the charge generation layer 5 can be arbitrarily set to give good electrical characteristics and image quality, but is preferably 0.01 to 5 μm, and 0.05 to 2.0 μm. More preferred.

  Since the charge transport layer 6 is a surface layer in the present embodiment, it contains fluorine resin particles and a fluorine graft polymer in addition to the charge transport material and the binder resin.

  Fluorine-based resin particles include tetrafluoroethylene resin, trifluorinated ethylene resin, hexafluoroethylenepropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin, and copolymers thereof. It is preferable when it consists of 1 type, or 2 or more types of resin chosen from these.

  The average primary particle diameter of the fluorine resin particles is preferably 0.05 to 1.0 μm. When the average primary particle diameter is less than 0.05 μm, aggregation during dispersion tends to proceed. On the other hand, when the average primary particle diameter exceeds 1.0 μm, image quality defects are likely to occur. From such a viewpoint, the average primary particle diameter of the fluorine-based resin particles is more preferably 0.1 to 0.3 μm.

  The fluorine resin particles contained in the charge transport layer 6 of the present embodiment are the total number of primary particles and secondary particles containing primary particles and secondary particles having a particle diameter of less than 1 μm. Is 80% or more. In other words, the fluorine resin particles have a content ratio of secondary particles having a particle diameter of 1 μm or more of less than 20% with respect to the total number of primary particles and secondary particles of the fluorine resin particles.

  Thereby, although the frictional force between the toner and the blade of the cleaning device does not change, it is considered that the frictional force between the surface layer and the toner attached to the surface layer is reduced.

  Therefore, even when the cleaning device provided in the conventional image forming apparatus is used, the toner is sufficiently removed from the surface layer of the photoreceptor by the blade of the cleaning device. In addition, when the toner is obtained by emulsion polymerization or described in Patent Document 1, the frictional force between the surface layer of the photosensitive layer and the toner is reduced. Is sufficiently removed from the surface layer of the photoreceptor.

  Further, when the toner is produced by a kneading and pulverizing method, the toner is pulverized relatively easily and finely divided at the time of image formation. If the electrophotographic photosensitive member of the present invention is used, the toner is a photosensitive member. Remaining in the surface layer is sufficiently suppressed. Therefore, even when a two-component developer containing the toner and the carrier is used as the developer, the finely divided toner is fused to the carrier or the developing sleeve and the charging deterioration of the developer is accelerated. The phenomenon seen in the past is less likely to occur.

  Even when a one-component developer containing a magnetic toner or a non-magnetic toner is used as a developer, the adhesion of the toner becomes stronger due to the refinement of the toner. Therefore, it is difficult to cause the phenomenon that has been seen so far, such that the image quality is lowered.

  When the content ratio of the primary particles and the secondary particles having a particle diameter of less than 1 μm is less than 80%, the frictional force of the photosensitive member with respect to the toner becomes relatively high. May cause failure. From such a viewpoint, the content ratio of the primary particles and the secondary particles having a particle diameter of less than 1 μm is more preferably 90% or more, and further preferably 98% or more.

  Here, the calculation method for the content ratio of the primary particles of the fluorine resin particles and the secondary particles having a particle diameter of less than 1 μm with respect to the total number of primary particles and secondary particles of the fluorine resin particles is described with reference to FIG. However, it explains in detail.

  First, using a conventional microscope capable of observing a substance in the order of nm to μm such as TEM or SEM (scanning electron microscope), the surface layer of the photoreceptor is photographed by a usual method to obtain a photograph thereof. (FIG. 4 is a TEM photograph). Next, (A) primary particles having a particle diameter of less than 1 μm, (B) particles of fluororesin particles found to be present within a predetermined range of the obtained photograph (33 μm × 27 μm (vertical x horizontal in the photograph) in FIG. 4), The numbers of primary particles having a diameter of 1 μm or more, (C) secondary particles having a particle diameter of less than 1 μm, and (D) secondary particles having a particle diameter of 1 μm or more are counted. At this time, the primary particles contained in the secondary particles are not counted as the primary particles of (A) and (B).

Next, the number of the resulting above four fluorine resin particles each N _A, N _B, as N _C and N _D, the following equation (1), the primary particles and secondary particles of the fluorine-based resin particles The content ratio R of the primary particles of the fluorine resin particles and the secondary particles having a particle diameter of less than 1 μm is calculated with respect to the total number.
_{R = (N A + N C} ) / (N A + N B + N C + N D) × 100 (%) ... (1)
The fluorine-based graft polymer is not particularly limited as long as it is a conventionally used fluorine-based graft polymer. Among them, a resin obtained by graft polymerization from a macromonomer composed of an acrylic ester compound, a methacrylic ester compound or a styrene compound and perfluoroalkylethyl methacrylate is preferable.

  The content ratio of the fluororesin particles in the charge transport layer 6 (surface layer) is preferably 0.1 to 40% by mass with respect to the total mass of the solid component of the charge transport layer 6 (surface layer). More preferably, it is 1-30 mass%. If the content ratio is less than 1% by mass, the tendency to be unable to sufficiently obtain the modification effect due to the dispersion of the particles containing the fluorine-containing resin increases. On the other hand, when the content ratio exceeds 40% by mass, the light transmission property of the charge transport layer 6 (surface layer) is lowered, and the residual potential may be increased by repeated use.

  The fluorine-based graft polymer is used as a dispersion of fluorine-based resin particles, and functions as a dispersion aid for improving the dispersion stability and for preventing aggregation at the time of coating film formation. Therefore, from the viewpoint of optimally dispersing the fluorine-based resin particles, the fluorine-based graft polymer preferably has a ratio of 1.5 to 2.5% by mass with respect to the mass of the fluorine-based resin particles, and 1.6 to 2 More preferably, it is 2% by mass. When the content is less than 1.5% by mass, the function as a dispersion of fluororesin particles is not sufficient. On the other hand, when the content ratio exceeds 2.5% by mass, the residual potential increases due to repeated use.

  In the present invention, in order to sufficiently achieve the above-described problems of the present invention or to fully exhibit the effect, it is preferable to use the charge generation layer as a surface layer, rather than to use a protective layer described later as a surface layer.

    The charge transport material contained in the charge transport layer 6 is not particularly limited, and a known material can be used. For example, oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline or 1- [pyridyl- (2)] Pyrazoline derivatives such as -3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine, tri ( aromatic tertiary amino compounds such as p-methylphenyl) aminyl-4-amine or dibenzylaniline, and aromatic tertiary amino compounds such as N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine. -Class diamino compound, 3- (4'-dimethylaminophenyl) -5,6-di- (4'-methoxyphenyl) -1,2,4-triazi 1,2,4-triazine derivatives, such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2,3-di Benzofuran derivatives such as (p-methoxyphenyl) benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole or poly- Hole transport materials such as N-vinylcarbazole or derivatives thereof, quinone compounds such as chloranil or broanthraquinone, tetraanoquinodimethane compounds, 2,4,7-trinitrofluorenone or 2,4,5,7- Full such as tetranitro-9-fluorenone Examples thereof include an electron transport material such as an oleone compound, a xanthone compound or a thiophene compound, or a polymer having a group composed of the above-described compound in the main chain or side chain. These charge transport materials can be used alone or in combination of two or more.

  The binder resin contained in the charge transport layer 6 is not particularly limited, and a known resin can be used. Specifically, for example, polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene copolymer resin, acrylonitrile- Butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, phenol -Insulating resin such as formaldehyde resin, polyacrylamide resin, polyamide resin or chlorine rubber, or polyvinylcarbazole, polyvinylanthracene or polyvinyl chloride Organic photoconductive polymers such as Rupiren like. These binder resins can be used singly or in combination of two or more.

  The blending ratio (mass ratio) of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 from the viewpoint of sufficiently suppressing the decrease in electrical characteristics and film strength.

  Further, the charge transport layer 6 of the present embodiment may contain inorganic particles in order to improve mechanical strength. Specifically, for example, alumina, silica (silicon dioxide), titanium oxide, zinc oxide, cerium oxide, zinc sulfide, magnesium oxide, copper sulfate, sodium carbonate, magnesium sulfate, potassium chloride, calcium chloride, sodium chloride, nickel sulfate , Antimony, manganese dioxide, chromium oxide, tin oxide, zirconium oxide, barium sulfate, aluminum sulfate, silicon carbide, titanium carbide, boron carbide, tungsten carbide or zirconium carbide particles, or one of these particles alone Alternatively, two or more kinds of particles are used in combination as necessary, but silica particles are preferably used.

  As the silica particles, known particles can be used, but silica particles produced by a chemical flame CVD method are preferred, and chlorosilane gas is vapor-phased in a high-temperature flame of oxygen-hydrogen mixed gas or hydrocarbon-oxygen mixed gas. Silica particles obtained by reaction are more preferred.

  In addition to the above, inorganic particles having a hydrophobic particle surface are preferable. As the hydrophobizing agent used for hydrophobizing the surface of the inorganic particles, for example, a siloxane compound, a silane coupling agent, a titanium coupling agent, a polymer fatty acid or a metal salt thereof is used. Examples of the siloxane compound include polydimethylsiloxane, dihydroxypolysiloxane, octamethylcyclotetrasiloxane, and examples of the silane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2- Aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane , Butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylsilane Examples include phenyltrimethoxysilane and p-methylphenyltrimethoxysilane.

  The average primary particle diameter of the inorganic particles is preferably 0.005 to 2.0 μm, and more preferably 0.01 to 1.0 μm. If the average primary particle diameter of the inorganic particles is less than 0.005 μm, sufficient mechanical strength on the surface of the photoreceptor cannot be obtained, and aggregation during dispersion tends to proceed. On the other hand, when the average primary particle diameter of the inorganic particles exceeds 2 μm, the surface roughness of the photoreceptor increases, the cleaning blade is worn and damaged, the cleaning characteristics are deteriorated, and image blur is likely to occur.

  The content ratio of the inorganic particles in the charge transport layer 6 is preferably 0.1 to 20% by mass and more preferably 1 to 20% by mass with respect to the total mass of the charge transport layer 2. When the content is less than 1% by mass, the mechanical strength is not sufficiently improved by the dispersion of the inorganic particles. On the other hand, when the content ratio exceeds 30% by mass, the light transmission property is lowered, and further, poor dispersion tends to occur.

  The layer thickness of the charge transport layer 6 is preferably 5 to 50 μm, and more preferably 10 to 40 μm.

  Furthermore, the electrophotographic photoreceptor 1 of this embodiment may have a configuration in which an intermediate layer (not shown) is disposed between the photosensitive layer 3 and the conductive substrate 2 as necessary. This intermediate layer is provided in order to improve the electrical characteristics of the photoreceptor, improve the image quality, and improve the adhesion of the photosensitive layer.

  The constituent material of the intermediate layer is not particularly limited, and can be arbitrarily selected from a binder resin, an organic or inorganic powder, an electron transporting material, and the like.

  As the binder resin of the intermediate layer, acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin And a polymer resin compound such as vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, or melamine resin.

  Alternatively, a known material such as an organometallic compound containing zirconium, titanium, aluminum, manganese, silicon, or the like can be used.

  These compounds can be used individually by 1 type or in mixture of 2 or more types or as a polycondensate. Among these, organometallic compounds containing zirconium or silicon are preferable because they have excellent performance such as low residual potential, little potential change due to environment, and little potential change due to repeated use.

  Examples of the organic compound containing zirconium include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl zirconium acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, and octane. Zirconate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide or isostearate zirconium butoxide.

  Examples of the organic compound containing silicon include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycid. Xylpropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (amino And ethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. Among these, particularly preferable organic compounds containing silicon include vinyltriethoxysilane, vinyltris (2-methoxyethoxysilane), 3-methacryloxypropyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, Examples include silane coupling agents such as 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

  Examples of the organic compound containing titanium include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, and titanium octylene glycolate. , Titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamate or polyhydroxytitanium stearate.

  Examples of the organic compound containing aluminum include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate).

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer.However, if the film thickness is too large, the electrical barrier becomes too strong, and potential due to desensitization and repetition Cause a rise. Therefore, the thickness of the intermediate layer is preferably 0.1 to 3 μm.

  Further, this intermediate layer can also act as an undercoat layer in the embodiment of the electrophotographic photoreceptor according to FIG.

  FIG. 2 is a cross-sectional view of an essential part schematically showing another preferred embodiment of the electrophotographic photosensitive member of the present invention. In the electrophotographic photoreceptor 21 shown in FIG. 2, the undercoat layer 4, the charge generation layer 5, and the charge transport layer 6 are laminated in this order on the conductive substrate 2 to form the photosensitive layer 13. Among these, the conductive substrate 2, the charge generation layer 5, and the charge transport layer 6 are the same as those provided in the above-described electrophotographic photosensitive member shown in FIG.

  The undercoat layer 4 of this embodiment is formed on the conductive substrate 2 in a state where a conductive substance is dispersed in a binder resin.

  Examples of the conductive material include metal powders such as aluminum, copper, nickel, and silver, conductive metal oxides such as antimony oxide, indium oxide, tin oxide, and zinc oxide, carbon fiber, carbon black, and graphite powder. And so on.

  Among these, when a conductive metal oxide is used, the metal oxide is preferably in the form of particles having an average primary particle diameter of 0.5 μm or less.

The undercoat layer 4 needs to have an appropriate resistance for obtaining leak resistance. Therefore, the metal oxide particles need a powder resistance of about 10 ² to 10 ¹¹ Ω · cm. Therefore, it is more preferable to use a metal oxide such as tin oxide, titanium oxide or zinc oxide having a resistance value within the above range. If the resistance value of the metal oxide particles is lower than 10 ² Ω · cm, sufficient leakage resistance cannot be obtained, and if it is higher than 10 ¹¹ Ω · cm, there is a concern that the residual potential is increased.

  Moreover, 2 or more types of metal oxides can be mixed and used. Furthermore, it is more preferable to use metal oxide particles that have been surface-treated with a coupling agent as the conductive material because the powder resistance can be adjusted.

  Any coupling agent can be used as long as it can obtain desired photoreceptor characteristics. Specific examples of coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycid. Xylpropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (amino Examples include silane coupling agents such as ethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and γ-chloropropyltrimethoxysilane. It is not limited to. Moreover, these coupling agents can also be used in mixture of 2 or more types.

  As the surface treatment method of the metal oxide particles, any known method can be used, and a dry method or a wet method can be used. When surface treatment is performed by a dry method, the metal oxide particles are stirred with a mixer having a large shearing force, and at the same time, the coupling agent is dropped directly or dissolved in an organic solvent or water, together with dry air or nitrogen gas. It is uniformly processed by spraying. The addition or spraying is preferably performed at a temperature of 50 ° C. or higher. After addition or spraying, baking can be performed at 100 ° C. or higher.

  Baking can be carried out under any conditions as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the dry method, the surface adsorbed water may be removed by heating and drying the metal oxide particles before the surface treatment with the coupling agent. By removing the surface adsorbed water before the surface treatment, the coupling agent can be uniformly adsorbed on the surface of the metal oxide particles.

  In the wet method, the metal oxide particles are dispersed in a solvent by stirring or using an ultrasonic wave, a sand mill, an attritor, or a ball mill, and the coupling agent solution is added and stirred or dispersed, and then the solvent is removed. By doing so, the surface is treated uniformly. After removing the solvent, baking may be performed at 100 ° C. or higher.

  Baking can be carried out under any conditions as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. Even in the wet method, the surface adsorbed water of the metal oxide particles can be removed before the surface treatment with the coupling agent. As a method for removing the surface adsorbed water, in addition to the heat drying similar to the dry method, a method of removing with stirring and heating in a solvent used for the surface treatment or a method of removing by azeotropy with the solvent can be performed.

  It is preferable to adjust the amount of the surface treatment agent relative to the metal oxide particles so that the desired electrophotographic characteristics can be obtained.

The electrophotographic characteristics are affected by the amount of coupling agent adhering to the metal oxide particles after the surface treatment. In the case of the silane coupling agent, the adhering amount depends on the Si intensity in the fluorescent X-ray analysis and the metal oxide. It is calculated | required from ratio with the main metal element strength of. A preferable Si intensity ratio in the fluorescent X-ray analysis is preferably in the range of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻³ with respect to the main metal element intensity of the metal oxide. When this ratio is below 1.0 × 10 ⁻⁵ , image quality defects such as fog are likely to occur, and when this ratio is above 1.0 × 10 ⁻³ , density reduction occurs due to an increase in residual potential. Cheap.

  Examples of the binder resin contained in the undercoat layer 4 include acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, and polyvinyl chloride. Resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, or other known polymer resin compounds, or charge transport A charge transporting resin having a functional group or a conductive resin such as polyaniline can be used.

  Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used.

  The ratio of the conductive material and the binder resin in the undercoat layer 4 can be arbitrarily set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

  The thickness of the undercoat layer 4 is preferably 15 μm or more, more preferably 20 to 50 μm, from the viewpoint of preventing photoconductor leakage. However, if it has sufficient leakage resistance and the occurrence of the above-described leakage defect is not a concern, the thickness of the undercoat layer 4 can be set to be thinner than 15 μm. Applicable to thin films of about 1 μm. The undercoat layer 4 preferably has a Vickers strength of 35 or more.

  Further, the surface roughness of the undercoat layer 4 is adjusted from ¼ n (n is the refractive index of the upper layer) of the exposure laser wavelength λ used to prevent moiré images. Resin particles can be added to the undercoat layer 4 to adjust the surface roughness. As the resin particles, silicone resin particles, cross-linked PMMA resin particles, and the like can be used. Furthermore, the undercoat layer 4 may have a surface polished to adjust the surface roughness. As the polishing method, buffing, sand blasting, wet honing or grinding can be used.

  Further, the electrophotographic photosensitive member 21 of the present embodiment is provided between the photosensitive layer 13 (undercoat layer 4) and the conductive substrate 2 or between the charge generation layer 5 and the undercoat layer 4 as necessary. The intermediate layer (not shown) described above may be arranged.

  FIG. 3 is a cross-sectional view of an essential part schematically showing still another preferred embodiment of the electrophotographic photosensitive member of the present invention. In the electrophotographic photoreceptor 21 shown in FIG. 3, the undercoat layer 4, the charge generation layer 5, the charge transport layer 26 and the protective layer 7 are laminated on the conductive substrate 2 in this order to form the photosensitive layer 23. ing. Among these, the conductive substrate 2, the undercoat layer 4 and the charge generation layer 5 are the same as those provided in the above-described electrophotographic photosensitive member shown in FIG. 1 or FIG. To do.

  Unlike the charge transport layer 6 in the electrophotographic photoreceptor 1 and the charge transport layer 16 in the electrophotographic photoreceptor 2 described above, the charge transport layer 26 according to the present embodiment does not become a surface layer of the electrophotographic photoreceptor 21. Therefore, the charge transport layer 26 only needs to contain the charge transport material and the binder resin, and does not need to contain the fluorine resin particles or the fluorine graft polymer. Further, even when the fluorine-based resin particles are contained, the primary particles and the secondary particles of the fluorine-based resin particles have a content ratio of primary particles of the fluorine-based resin particles and secondary particles having a particle diameter of less than 1 μm. It is not necessary to be 80% or more with respect to the total number. However, the charge transport layer 26 may satisfy these conditions. Furthermore, the charge transport layer 26 may appropriately include a substance contained in a known charge transport layer as necessary.

  Since the charge transport layer 26 is the same as the charge transport layer 6 described above with respect to materials other than those described above, detailed description thereof will be omitted.

  Since the protective layer 7 corresponds to the surface layer of the electrophotographic photosensitive member 21 in the present embodiment, the protective layer 7 contains fluorine-based resin particles and a fluorine-based graft polymer. Regarding the types and content ratios of the fluorine-based resin particles and fluorine-based graft polymer contained in the protective layer 7 and the average primary particle size and particle size distribution of the fluorine-based resin particles, the charge transport layer of the electrophotographic photoreceptor 1 described above 6 is the same as that contained in FIG.

  In addition to functioning as a surface layer of the present invention, the protective layer 7 prevents chemical changes in the charge transport layer 26 during charging of the electrophotographic photosensitive member 21 or further improves the mechanical strength of the photosensitive layer 23. Used. The protective layer 7 may be a so-called insulating resin protective layer containing an insulating resin (binder resin) in addition to the fluorine-based resin particles and the fluorine-based graft polymer, or the insulating resin. A so-called low resistance protective layer in which a conductive substance (resistance adjusting agent) is added may be used.

  The conductive substance (resistance adjusting agent) is not particularly limited, and examples thereof include metallocene compounds such as N, N′-dimethylferrocene, N, N′-diphenyl-N, N′-bis (3-methylphenyl). )-[1,1′biphenyl] -4,4′-diamine and other aromatic amine compounds, molybdenum oxide, tungsten oxide, antimony oxide, tin oxide, titanium oxide, indium oxide and other metal oxides, tin oxide and antimony Or a solid solution carrier of barium sulfate and antimony oxide, a mixture of the above metal oxides, a mixture of the above metal oxides in a single particle of titanium oxide, tin oxide, zinc oxide or barium sulfate, or titanium oxide In addition, a single particle of tin oxide, zinc oxide, or barium sulfate is coated with the above metal oxide.

  Examples of the insulating resin (binder resin) used for the protective layer 7 include polyamide resin, polyvinyl acetal resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, A known resin such as a polyimide resin or a polyamideimide resin is used. Alternatively, they can be used by cross-linking each other as necessary.

  The layer thickness of the protective layer 7 is preferably 0.1 to 10 μm, and more preferably 0.5 to 7 μm.

    Further, the electrophotographic photoreceptor 21 of the present embodiment is provided between the photosensitive layer 23 (undercoat layer 4) and the conductive substrate 2 or between the charge generation layer 5 and the undercoat layer 4 as necessary. In addition, the above-described intermediate layer (not shown) may be arranged.

  The preferred embodiment of the electrophotographic photosensitive member of the present invention has been described above, but the present invention is not limited to the above embodiment.

(Method for producing electrophotographic photoreceptor)
Next, a preferred embodiment of the method for producing an electrophotographic photosensitive member of the present invention will be described. In the method for producing the electrophotographic photosensitive member of the present invention, the procedure and conditions in the production process of other components of the electrophotographic photosensitive member other than the photosensitive layer are not particularly limited. Can be used.

  First, a conductive substrate is prepared. When this conductive substrate is a metal pipe, its surface may be left untreated, but it has been subjected to processing such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting or wet honing. May be.

  Next, an intermediate layer is formed on the conductive substrate as necessary. The intermediate layer is formed by mixing the above-described constituent materials in an organic solvent to prepare a coating solution, coating the obtained coating solution on a conductive substrate, and further drying.

  Examples of the organic solvent used in the coating liquid for forming the intermediate layer include known organic solvents such as aromatic hydrocarbon solvents such as toluene or chlorobenzene, methanol, ethanol, n-propanol, iso-propanol, or n-butanol. Aliphatic alcohol solvents, ketone solvents such as acetone, cyclohexanone or 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform or ethylene chloride, cyclic such as tetrahydrofuran, dioxane, ethylene glycol or diethyl ether or Examples include linear ether solvents, ester solvents such as methyl acetate, ethyl acetate, and n-butyl acetate. These solvents can be used alone or in combination of two or more. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  As a coating method for forming the intermediate layer, a usual method such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method or a curtain coating method can be used.

  Next, an undercoat layer is formed on the conductive substrate or intermediate layer as necessary. The undercoat layer is prepared by dispersing the above-described conductive substance particles in a binder resin in an organic solvent to prepare a coating solution, coating the coating solution on a conductive substrate or intermediate layer, and further drying the coating solution. It is formed.

  The organic solvent used in the coating solution may be arbitrarily selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers, and esters. it can.

  More specifically, for example, alcohols such as methanol, ethanol, isopropanol or n-butanol, ketones such as acetone, methyl ethyl ketone or cyclohexanone, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether or diethyl ether, chloroform, Aliphatic halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride or trichloroethylene, amides such as N, N-dimethylformamide or N, N-dimethylacetamide, methyl acetate, ethyl acetate or n-butyl acetate Examples include esters, or aromatics such as benzene, toluene, xylene, monochlorobenzene, or dichlorobenzene. Not intended to be.

    Moreover, the organic solvent used for these dispersion | distribution can be used individually by 1 type or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  The ratio between the conductive material particles and the binder resin in the coating solution for forming the undercoat layer can be arbitrarily set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

  Various additives can be used in the coating solution in order to improve electrical characteristics, environmental stability or image quality. Additives include quinone compounds such as chloranil, bromoanil or anthraquinone, tetracyanoquinodimethane compounds, fluorenone such as 2,4,7-trinitrofluorenone or 2,4,5,7-tetranitro-9-fluorenone Compound, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (4-naphthyl) -1,3,4-oxadi Oxadiazole compounds such as azole or 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, xanthone compounds, thiophene compounds or 3,3 ′, 5,5′-tetra- Electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone, electron transporting pigments such as polycyclic condensed or azo series, Hexafluorophosphate chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, may be a known material such as an organic titanium compound or a silane coupling agent.

  Of these, the silane coupling agent is used for surface treatment of metal oxide particles that are conductive materials, but may be further added to the coating solution as an additive. Specific examples of the silane coupling agent used here may be the same as the specific examples of the silane coupling agent used for the surface treatment of the metal oxide particles.

  Examples of the zirconium chelate compound include zirconium butoxide, zirconium zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide or isostearate zirconium butoxide.

  Examples of the titanium chelate compound include tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium salt. , Titanium lactate, titanium lactate ethyl ester, titanium triethanolamate, or polyhydroxytitanium stearate.

  Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxy aluminum diisopropylate, aluminum butyrate, diethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethyl acetoacetate).

  These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds.

  As a method for dispersing the conductive material particles in the binder resin, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill or a horizontal sand mill, or a media such as a stirring, ultrasonic dispersing machine, roll mill or high-pressure homogenizer is used. Less dispersers can be used. Further, as a high-pressure homogenizer, there are a collision type that disperses the liquid dispersion by liquid-liquid collision or liquid-wall collision in a high pressure state, or a penetration type that disperses by penetrating a fine flow path in a high pressure state. Can be mentioned.

  As a coating method for forming the undercoat layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method can be used.

  Subsequently, an intermediate layer may be formed on the undercoat layer as necessary. The formation method can be the same as that described above except that it is formed on the undercoat layer instead of being formed on the conductive substrate. Omitted.

  Next, a charge generation layer is formed on the conductive substrate, intermediate layer or undercoat layer. The charge generation layer is prepared by mixing a charge generation material, an organic solvent described later, a binder resin, an additive thereof (for example, a dispersion aid for the charge generation material), and the like to prepare a coating solution for forming the charge generation layer. It is obtained by applying this onto a conductive substrate, intermediate layer or undercoat layer and further drying.

  As the solvent contained in the coating solution, known organic solvents, for example, aromatic hydrocarbon solvents such as toluene or chlorobenzene, aliphatic alcohols such as methanol, ethanol, n-propanol, iso-propanol or n-butanol Solvents, ketone solvents such as acetone, cyclohexanone or 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform or ethylene chloride, cyclic or linear ether systems such as tetrahydrofuran, dioxane, ethylene glycol or diethyl ether A solvent or an ester solvent such as methyl acetate, ethyl acetate, or n-butyl acetate can be used.

  These solvents can be used alone or in combination of two or more. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent.

  As a method for dispersing the charge generating material in the coating liquid, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill or a horizontal sand mill, or a medialess disperser such as an agitator, an ultrasonic disperser, a roll mill or a high-pressure homogenizer. Is available. Furthermore, as a high-pressure homogenizer, there are a collision type that disperses the liquid dispersion by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration type that disperses through a fine flow path in a high pressure state. Can be mentioned.

  As a coating method for forming the charge generation layer, a usual method such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method or a curtain coating method can be used.

  Next, a charge transport layer is formed on the charge generation layer. When the charge transport layer is a surface layer (for example, the electrophotographic photoreceptor 1 shown in FIG. 1), first, at least the above-described fluorine-based resin particles, fluorine-based graft polymer, binder resin, and organic solvent are mixed. To obtain a mixture (mixing step). More specifically, for example, after a binder resin, a charge transport material, and a fluorine-based graft polymer are mixed in an organic solvent to obtain a solution, the fluorine-based resin particles are mixed into the solution. At this time, additives such as the inorganic particles described above may be mixed as necessary.

  Examples of the organic solvent include known organic solvents, for example, aromatic hydrocarbon solvents such as toluene or chlorobenzene, aliphatic alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol or n-butanol, acetone, Ketone solvents such as cyclohexanone or 2-butanone, halogenated aliphatic hydrocarbon solvents such as methylene chloride, chloroform or ethylene chloride, cyclic or linear ether solvents such as tetrahydrofuran, dioxane, ethylene glycol or diethyl ether, methyl acetate An ester solvent such as ethyl acetate or n-butyl acetate can be used. These organic solvents can be used individually by 1 type or in mixture of 2 or more types. When mixing, any organic solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  Subsequently, the mixture passes through a dispersion step in order to mainly disperse the fluorine resin particles in the coating solution. As a dispersion method used in the dispersion step, for example, dispersion using a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill or a horizontal sand mill, a media disperser such as a stirring, an ultrasonic disperser, a roll mill or a high pressure homogenizer. There is a method using an apparatus.

  Among these, in order to disperse the fluororesin particles in the charge transport layer so as to satisfy the above-described conditions, it is preferable to employ a method using a high-pressure homogenizer that is a medialess disperser. As such a high-pressure homogenizer, for example, a through-type one that penetrates and disperses fine channels in a high-pressure state can be cited.

Further, in order to improve the dispersibility of the fluororesin particles, the pressure at which the fluororesin particles are circulated in the high-pressure homogenizer together with the solution in which the binder resin and the fluorograft polymer are dissolved in an organic solvent is 300 kg / It is more preferable to set it to cm ² or more and less than 700 kg / cm ² . When this pressure is set to less than 300 kg / cm ² and circulates, secondary particles having a particle diameter of 1 μm or more tend to be generated. Therefore, in this case, the content ratio of the primary particles of the fluororesin particles in the charge transport layer and the secondary particles having a particle diameter of less than 1 μm is based on the total number of primary particles and secondary particles of the fluororesin particles. Tend to be less than 80%. On the other hand, even when this pressure is set to 700 kg / cm ² or more and circulates, secondary particles having a particle diameter of 1 μm or more tend to be generated. Therefore, also in this case, the content ratio of the primary particles of the fluororesin particles in the charge transport layer and the secondary particles having a particle diameter of less than 1 μm is the total number of primary particles and secondary particles of the fluororesin particles. On the other hand, it tends to be less than 80%. As a result, it becomes difficult to maintain the low friction with respect to the toner of the photoconductor, which may cause a decrease in toner transfer rate and poor cleaning after repeated use.

Factors that decrease the dispersibility of the fluororesin particles even when this pressure is set to 700 kg / cm ² or more include viscosity change due to temperature rise, desorption or fracture of the fluorograft polymer from the surface of the fluororesin particles. Conceivable. However, the factor is not limited to this.

  In order to obtain the electrophotographic photoreceptor of the present invention, the mixture is preferably processed twice or more by a high-pressure homogenizer, and more preferably 4 to 8 times. If the treatment with the high-pressure homogenizer is less than twice, it becomes difficult to obtain a desired electrophotographic photosensitive member, and even if the treatment is performed more than 8 times, it is compared with the effect obtained by being processed within the above range. As a result, the difference does not occur so much that it consumes excessive time, labor and cost.

  In addition to the above-described high-pressure homogenizer, a high-pressure homogenizer such as a collision type that disperses liquid-liquid collision or liquid-wall collision in a high-pressure state can be used.

  Next, the charge transport layer is obtained by applying the dispersion liquid in which the fluororesin particles obtained by the dispersion step are dispersed on the charge generation layer and drying. As a method for applying the dispersion liquid, a usual method such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method or a curtain coating method can be used.

  When the charge transport layer is a surface layer, the electrophotographic photosensitive member is completed as described above.

  Further, when a protective layer is further formed on the charge transport layer, that is, when the charge transport layer is not formed as a surface layer, the fluorine resin particles or the fluorine graft polymer is not an essential component of the charge transport layer. Therefore, in this case, first, at least the binder resin and the organic solvent described above are mixed with other additives such as the inorganic particles described above as necessary. Next, the obtained mixture is appropriately dispersed using the above-described dispersing device, and applied to the charge generation layer using the method described above and dried to obtain a charge transport layer.

  Next, an electrophotographic photosensitive member is obtained by forming a protective layer on the charge transport layer as necessary. First, at least the above-mentioned fluorine-based resin particles, fluorine-based graft polymer, insulating resin (binder resin) and an organic solvent are mixed to obtain a mixture (mixing step). At this time, an additive such as the above-described conductive substance (resistance adjusting agent) may be mixed as necessary.

  The organic solvent can be arbitrarily selected from known organic solvents such as alcohols, aromatics, halogenated hydrocarbons, ketones, ketone alcohols, ethers and esters.

  More specifically, for example, alcohols such as methanol, ethanol, isopropanol or n-butanol, ketones such as acetone, methyl ethyl ketone or cyclohexanone, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether or diethyl ether, chloroform, Aliphatic halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride or trichloroethylene, amides such as N, N-dimethylformamide or N, N-dimethylacetamide, methyl acetate, ethyl acetate or n-butyl acetate Examples include esters, or aromatics such as benzene, toluene, xylene, monochlorobenzene, or dichlorobenzene. Not intended to be.

    Moreover, these organic solvents can be used individually by 1 type or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as a mixed solvent. Among these, it is preferable to use an organic solvent that hardly dissolves the charge transport layer.

  Subsequently, the mixture passes through a dispersion step in order to mainly disperse the fluorine resin particles in the coating solution. Since the dispersion method used in the dispersion step, the preferred dispersion method, and the more preferred dispersion method are the same as those employed when the charge transport layer is formed as the surface layer, detailed description thereof is omitted here.

  Next, the protective layer is obtained by applying the dispersion liquid in which the fluororesin particles obtained by the dispersion step are dispersed on the charge transport and drying. Since the coating method is the same as that employed when forming the charge transport layer as the surface layer, detailed description thereof is omitted here.

  In the photosensitive layer, an additive such as an antioxidant, a light stabilizer or a heat stabilizer is used from the viewpoint of preventing deterioration of the photoreceptor due to ozone or nitrogen oxide generated in the image forming apparatus or light or heat. Can be added as needed. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman or spirodanone, or a derivative thereof, an organic sulfur compound, or an organic phosphorus compound. Examples of light stabilizers include derivatives such as benzophenone, benzoazole, dithiocarbamate, and tetramethylpipen. In order to improve the surface smoothness, a leveling agent such as silicone oil can be added to the surface layer.

  The preferred embodiment of the method for producing an electrophotographic photosensitive member of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Next, preferred embodiments of an image forming apparatus equipped with the electrophotographic photosensitive member of the present invention, an image forming method using the same, and a process cartridge will be described.

(Image forming apparatus, image forming method using the same, and process cartridge)
FIG. 5 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the image forming apparatus of the present invention. An image forming apparatus 200 shown in FIG. 5 includes an electrophotographic photosensitive member 207 of the present invention (for example, the above-described electrophotographic photosensitive member 1), a charging device 208 that charges the electrophotographic photosensitive member 207 by a contact charging method, and a charging device 208. A power source 209 connected to the exposure device, an exposure device 210 that exposes the electrophotographic photosensitive member 207 charged by the charging device 208 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure device 210 with toner. A developing device 211 that develops and forms a toner image, a transfer device 212 that transfers the toner image formed by the developing device 211 to a transfer medium, a cleaning device 213, a static eliminator 214, and a fixing device 215 are provided. . Although not shown in FIG. 5, a toner supply device that supplies toner to the developing device 211 is also provided. Moreover, in an embodiment different from the present embodiment, the static eliminator 214 may not be provided.

  A charging device 208 shown in FIG. 5 is a device in which a conductive member (charging roll) is brought into contact with the surface of the photoconductor 207 to uniformly apply a voltage to the photoconductor to charge the surface of the photoconductor to a predetermined potential. .

  As the conductive member, a member provided with an elastic layer, a resistance layer, a protective layer and the like on the outer peripheral surface of the core material is preferably used. The shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like.

  As the material of the core material, a conductive material such as iron, copper, brass, stainless steel, aluminum, nickel, or the like is used. Also, a resin molded product in which conductive particles or the like are dispersed can be used.

As the material of the elastic layer, a material having conductivity or semiconductivity, for example, a material in which conductive particles or semiconducting particles are dispersed in a rubber material can be used. As the rubber material, EPDM, polybutadiene, natural rubber, polyisobutylene, SBR, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer, norbornene rubber, fluorosilicone rubber, ethylene oxide rubber and the like are used. Examples of the conductive particles or semiconductive particles include carbon black, zinc, aluminum, copper, iron, nickel, chromium, titanium, and other metals, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O ₃ — Metal oxides such as SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO or MgO can be used. These materials can be used individually by 1 type or in mixture of 2 or more types.

  As the material of the resistance layer and the protective layer, conductive particles or semiconductive particles are dispersed in a binder resin, and the resistance is controlled. As binder resin, acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin, PFA, FEP or A polyolefin resin such as PET or a styrene butadiene resin is used. As the conductive particles or semiconductive particles, carbon black, metal, or metal oxide similar to the elastic layer is used. Further, if necessary, an antioxidant such as hindered phenol and hindered amine, a filler such as clay and kaolin, and a lubricant such as silicone oil can be added. As a means for forming these layers, a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain coating method, or the like can be used.

  When the photosensitive member 207 is charged using these conductive members, a voltage is applied to the conductive member. The applied voltage may be either a DC voltage or a DC voltage superimposed with an AC voltage.

  In addition to the charging roll shown in this embodiment, charging by a contact charging method may be performed using a charging brush, a charging film, a charging tube, or the like. Moreover, you may charge by the non-contact system using a corotron or a scorotron.

  As the exposure apparatus 210, an optical system apparatus that can expose a light source such as a semiconductor laser, an LED (light emitting diode), and a liquid crystal shutter on the surface of the electrophotographic photosensitive member 207 in a desired image-like manner can be used. Among these, when an exposure apparatus capable of exposing non-interference light is used, interference fringes between the conductive substrate of the electrophotographic photosensitive member 207 and the photosensitive layer can be prevented.

  As the developing device 211, a conventionally known developing device using a regular or reversal developer such as a one-component system or a two-component system can be used.

  The toner used in the developing device 211 is not particularly limited, but the toner described below is preferable in order to sufficiently achieve the object of the present invention or to fully exhibit the effects of the present invention. That is, a dispersion obtained by emulsion polymerization of a polymerizable monomer of a binder resin, a colorant, a release agent, and a dispersion of a charge control agent, if necessary, are mixed, A toner obtained by an emulsion polymerization aggregation method in which toner particles are obtained by heat fusion is preferable.

  Examples of the binder resin used for the toner include thermoplastic binder resins. Specifically, homopolymers or copolymers of styrenes such as styrene and parachlorostyrene (styrene resins); homopolymers or copolymers of esters having vinyl groups such as methyl acrylate and methyl methacrylate Polymer (vinyl resin); Homopolymer or copolymer of vinyl nitriles such as acrylonitrile and methacrylonitrile (vinyl resin); Homopolymer or copolymer of vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether (Vinyl resins); Homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone and vinyl ethyl ketone (vinyl resins); Homopolymers or copolymers of olefins such as ethylene and propylene (olefin resins) ); Epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose Resin, non-vinyl condensation resin of polyether resin and the like, or the like a graft polymer of these non-vinyl condensation resin and the vinyl monomer and the like. These binder resins may be used alone or in combination of two or more.

  Of these binder resins, vinyl resins are more preferable. In the case of a vinyl resin, it is advantageous in that a resin particle dispersion can be easily prepared by emulsion polymerization or seed polymerization using an ionic surfactant or the like.

  Examples of the vinyl monomer include, for example, vinyl polymer acids such as acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethyleneimine, vinyl pyridine, and vinyl amine, and vinyl monomers. Examples thereof include monomers that are raw materials for polymer bases.

  In this embodiment, it is preferable that the polymerizable monomer of the binder resin is emulsion-polymerized and the colorant is dispersed in the formed dispersion. Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, and brilliant. Carmine 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green or Malachite Green Oxalate Various pigments: acridine, xanthene, azo, benzoquinone, azine, anthraquinone, geo Spoon system, thiazine, azomethine, indigo, thioindigo, phthalocyanine, aniline black, polymethine, triphenylmethane dyes, diphenylmethane dyes, thiazine, and various dyes such as thiazole or xanthene systems.

  These colorants can be used alone or in combination of two or more as required. Moreover, the addition rate of this coloring agent is preferable in it being 2-20 mass parts with respect to resin solid content, and it is more preferable in it being 3-15 mass parts. This colorant may be used with its surface modified, and as the surface modifier, conventionally known ones can be used. Specifically, silane coupling agents, titanium coupling agents or It is preferable to use an aluminum coupling agent or the like.

  In this embodiment, the dispersion obtained by emulsion polymerization of the polymerizable monomer of the binder resin is used as a release agent, an internal additive, a charge control agent, inorganic particles, a lubricant, an abrasive, or the like. These components may be dispersed.

  Examples of the mold release agent include polyolefin wax, paraffin wax, oxidized paraffin wax, fatty acid ester wax, partially saponified fatty acid ester wax, 0001 mid wax or microcrystalline wax, or other known waxes. Among these, it is preferable to use polyolefin wax, and it is more preferable to use polypropylene wax or polyethylene wax. Also preferred is a polypropylene wax modified with a carboxylic acid such as maleic acid. In addition, you may use said polyolefin wax individually by 1 type or in combination of 2 or more types.

  Commercially available polyolefin waxes include Biscol 330P, Biscol 550P or Biscol 660P (Sanyo Kasei Kogyo Co., Ltd., polypropylene wax, trade name), High Wax 320P, High Wax 310P, High Wax 410P, High Wax 405P, High Wax 400P or high wax 200P (Mitsui Petrochemical Co., Ltd., polyethylene wax, trade name), Sun Wax 131P, Sun Wax 151P, Sun Wax 161P, Sun Wax 165P or Sun Wax 171P (Sanyo Kasei Kogyo Co., Ltd., Polyethylene) Wax, trade name) or polywax 400, polywax 500, polywax OH465 or polywax 1040 (above, Toyo Petrolite Co., Ltd., polyethylene) Wax, trade name) and the like.

  Further, the content ratio of the release agent is preferably 8 to 20 mass as the release agent ratio in the toner from the viewpoint of improvement of fluidity and improvement of cleaning property. Furthermore, the exposure rate of the release agent on the toner surface determined by X-ray photoelectron spectroscopy (XPS) is preferably 11 to 40 atomic%.

  As the charge control agent, known ones can be used. For example, a quaternary ammonium salt compound, a nigrosine compound, a dye comprising a complex of aluminum, iron young, chromium, etc., a triphenylmethane pigment, an azo metal A complex compound, a metal complex compound of salicylic acid, or a resin-type charge control agent containing a polar group can be used. When the toner of this embodiment is produced by an emulsion polymerization aggregation method, it is preferable to use a material that is difficult to dissolve in water from the viewpoint of controlling ionic strength and reducing wastewater contamination. The toner may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  Examples of the inorganic particles include various inorganic oxides, nitrides, borides and the like. Specifically, for example, silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, oxide Examples thereof include particles of tellurium, manganese oxide, calcium carbonate, magnesium carbonate, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, boron nitride, or calcium phosphate. Further, the inorganic particles may be subjected to a hydrophobic treatment. When performing the hydrophobizing treatment, it is preferable to hydrophobize with a so-called coupling agent such as various titanium coupling agents or silane coupling agents or silicone oil, or aluminum stearate, zinc stearate or calcium stearate. Hydrophobic treatment with a higher fatty acid metal salt such as is also preferred.

  Lubricants include higher fatty acid amides or higher fatty acid metal salts. Specifically, for example, fatty acid amides such as ethylene bis-stearamide, oleic acid amide, zinc stearate, salts of aluminum, copper, magnesium, calcium, zinc oleate, manganese, iron, copper, magnesium, etc. Salts, salts of zinc palmitate, copper, magnesium, calcium, etc., zinc linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  Examples of the abrasive include silica, alumina, and cerium oxide.

  Examples of the dispersion medium in the dispersion liquid in which the resin particles are dispersed or the resin fine particle dispersion liquid in which the resin fine particles are dispersed include an aqueous medium. Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Among these, in the present embodiment, it is preferable to add a surfactant to the aqueous medium and mix them. Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; Nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, polyhydric alcohols and the like can be mentioned. Among these, it is preferable to use an anionic surfactant or a cationic surfactant.

  When using the said nonionic surfactant, it is preferable to use together with an anionic surfactant or a cationic surfactant. Moreover, surfactant may be used individually by 1 type and may be used in combination of 2 or more type. Specific examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium dodecylsulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate and the like. Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

  As a method of dispersing the dispersion obtained by emulsion polymerization of the polymerizable monomer of the binder resin, a media dispersion machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, stirring, ultrasonic dispersion And a method using a medialess disperser such as a press machine, a roll mill, and a high-pressure homogenizer.

  In the step of heat fusion of the emulsion polymerization aggregation method, the heating temperature may be a decomposition temperature of the resin from the glass transition temperature of the resin contained in the adhered particles. Therefore, the heating temperature varies depending on the type of the binder resin and cannot be generally defined, but is generally 180 ° C. or lower, which is lower than the glass transition temperature of the resin contained in the adhered particles. In addition, the heating method can be performed using a known heating device / apparatus. Further, the fusion time may be relatively short when the heating temperature is high, and relatively long when the heating temperature is low. That is, since the fusion time depends on the heating temperature, it cannot be generally specified, but is generally about 30 minutes to 10 hours. In the present embodiment, the toner obtained through the heat-sealing step can be washed, dried, etc. under appropriate conditions.

  For the toner as described above, the toner and the external additive are added to the Henschel mixer or the V from the viewpoint of improving the fluidity and improving the cleaning property in order to enhance the suitability of the toner for the reusable image forming apparatus. It is preferable to add by mixing with a blender or the like. These external additives are not particularly limited, and various inorganic particles, organic particles and lubricants can be used.

  The particle size of the inorganic particles is preferably 0.1 to 3.0 μm, and more preferably 0.5 to 2.0 μm. Examples of the inorganic particles include inorganic oxides such as silica, alumina, and titania, nitrides, borides, and the like. Further, the inorganic particles may be subjected to a hydrophobic treatment.

  The amount of inorganic particles added to the toner is preferably greater than that of organic particles and lubricant. In addition to the inorganic particles, organic particles may be added. Examples of the organic particles include vinyl resin particles, styrene resin particles, styrene acrylic resin particles, polyester resin particles, urethane resin particles, and silicone resin particles. Examples of the lubricant include metal salts of higher fatty acids. The addition ratio of these external additives is preferably about 0.1 to 5% by mass with respect to the toner amount.

  The toner obtained by the above production method has a uniform shape, a small average particle size, and a sharp particle size distribution, unlike the case of production by a kneading and pulverization method.

  The average particle size of the toner is preferably 2 to 9 μm, and more preferably 3 to 8 μm. When the average particle diameter of the toner is less than 2 μm, the chargeability tends to be insufficient, and the developability tends to be lowered, and when it exceeds 9 μm, the resolution of the image tends to be lowered.

The particle size distribution (particle size distribution) is obtained by using the cumulative distributions D16 and D84 as an index, and volume GSD (volume GSD = (volume D84 / volume D16) ^0.5 ) or number GSD (number GSD = (number D84 / number D16) ^0.5 ) can be used simply. The volume GSD is preferably 1.30 or less, and more preferably 1.27 or less. When the volume GSD exceeds 1.30, developability tends to deteriorate with time due to selective development or the like.

By using the toner having an average shape factor of 115 to 140, it is possible to obtain an image with high development, transferability and high image quality. Here, the average shape factor of the toner particles is expressed by the following formula (2). In formula (2), ML is the absolute maximum length of the toner particles, and A is the projected area of the toner particles.
(Average shape factor of toner particles) = (ML ² / A) × (π / 4) × 100 (2)
The charge amount of the toner is preferably 10 to 40 μC / g, and more preferably 15 to 35 μC / g. When the charge amount is less than 10 μC / g, background stains are liable to occur, and when it exceeds 40 μC / g, the image density is liable to decrease. The ratio between the charge amount in summer and the charge amount in winter of the toner is preferably 0.5 to 1.5, more preferably 0.7 to 1.3. If this ratio is out of the numerical range, the toner is highly dependent on the environment, the charging property is not stable, and it tends to be unpreferable for practical use.

  The two-component developer toner is used by mixing with a carrier. As the carrier, iron powder, glass beads, ferrite powder or nickel powder, or those obtained by applying a resin coating on the surface thereof are used. The mixing ratio with the carrier can be set as appropriate.

  Examples of the transfer device 212 include a roller-type contact charging member, a contact-type transfer charger using a belt, a film, a rubber blade, or the like, a scorotron transfer charger using a corona discharge, a corotron transfer charger, or the like. .

  The cleaning device 213 is for removing residual toner adhering to the surface of the electrophotographic photosensitive member after the transfer process, and the electrophotographic photosensitive member cleaned by this is repeatedly used for the image forming process described above. . As the cleaning device, methods such as brush cleaning and roll cleaning can be used in addition to those using the illustrated cleaning blade. Among these, the cleaning blade is preferably used. Examples of the material for the cleaning blade include urethane rubber, neoprene rubber, and silicone rubber.

  Further, the image forming apparatus according to the present exemplary embodiment further includes a static eliminator such as a static eliminator (erase light irradiation device) 214 and an image fixing device 215 as shown in FIG. As a result, when the electrophotographic photosensitive member is repeatedly used, the phenomenon that the residual potential of the electrophotographic photosensitive member is brought into the next image forming cycle is prevented, so that the image quality can be further improved.

  FIG. 6 is a cross-sectional view schematically showing a basic configuration of another preferred embodiment of the image forming apparatus of the present invention. An image forming apparatus 201 shown in FIG. 6 includes an electrophotographic photosensitive member 207 of the present invention (for example, the above-described electrophotographic photosensitive member 1), a charging device 208 that charges the electrophotographic photosensitive member 207 by a contact charging method, and a charging device 208. A power source 209 connected to the exposure device, an exposure device 210 that exposes the electrophotographic photosensitive member 207 charged by the charging device 208 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure device 210 with toner. A developing device 211 that develops and forms a toner image, a transfer device 212 that transfers the toner image formed by the developing device 211 to a transfer medium, a cleaning device 213, a static eliminator 214, a fixing device 215, and a new device And a first toner supply device 231 for supplying the toner to the developing device 211, and further removed from the electrophotographic photosensitive member 207 by a cleaning device. A toner conveying device 230 for conveying the recovered toner, but also a second toner supplying device 232 for supplying recovered toner to the developing device 211.

  The toner transport device 230 transports the toner collected by the cleaning device 213 to the second toner supply device 232, and is connected to the cleaning device 213 and the second toner supply device 222. In the toner flow path in the toner conveying device 220, for example, a spiral member that rotates around the central axis of the toner flow path is provided to convey the toner. Further, the recovered toner is appropriately supplied from the second toner supply device 232 into the developing device 211 by rotating the supply roll 232a at a predetermined timing.

  In another embodiment different from the present embodiment, the collected toner may be supplied directly from the toner conveying device 230 into the developing device 211. In this case, the collected toner is appropriately supplied to the developing device 211 by adjusting the rotational speed of the spiral member described above.

  In the image forming apparatus provided with the toner conveying device 230, normally, the toner finely pulverized once through the image forming cycle is collected by the cleaning device 213, and then conveyed to the developing device 211 via the toner conveying device 230. Reused. At the time of collection by the cleaning device 213, the toner is further pulverized by the action of the blade of the cleaning device 213 and the photosensitive member, so that the charge deterioration of the developer becomes more remarkable and the toner is attached to the photosensitive member. The adhesion force is further increased, resulting in a problem that the transfer rate of the toner is reduced or the cleaning is poor.

  However, the image forming apparatus 201 of the present embodiment includes the above-described electrophotographic photosensitive member 207, so that the toner is easily peeled off from the photosensitive member 207 when being collected by the cleaning device 213. Is considered to be sufficiently suppressed. Therefore, the problems as described above are unlikely to occur.

  FIG. 7 is a cross-sectional view schematically showing a basic configuration of another embodiment of the image forming apparatus of the present invention. An image forming apparatus 220 shown in FIG. 7 is an intermediate transfer type image forming apparatus. In the housing 400, four electrophotographic photosensitive members 401a to 401d (for example, the electrophotographic photosensitive member 401a is yellow and the electrophotographic photosensitive member 401b is magenta). The electrophotographic photosensitive member 401c can form an image of cyan and the electrophotographic photosensitive member 401d can form a black color) are arranged in parallel along the intermediate transfer belt 409.

  Here, the electrophotographic photoreceptors 401a to 401d mounted on the image forming apparatus 220 are the electrophotographic photoreceptors of the present invention (for example, the electrophotographic photoreceptor 1).

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toner of four colors of black, yellow, magenta and cyan accommodated in the toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 401a to 401d.

  Further, a laser light source (exposure device) 403 is disposed at a predetermined position in the housing 400, and the surface of the electrophotographic photoreceptors 401a to 401d after charging is irradiated with laser light emitted from the laser light source 403. Is possible. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 passing between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 400, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. Then, the paper is sequentially transferred between the two fixing rolls 414 that are in contact with each other and the two fixing rolls 414 that are in contact with each other.

  In the above description, the case where the intermediate transfer belt 409 is used as the intermediate transfer member has been described. However, the intermediate transfer member may have a belt shape like the intermediate transfer belt 409 or a drum shape. Also good. In the case of a belt shape, a conventionally known resin can be used as the resin material used as the base material of the intermediate transfer member. For example, polyimide resin, polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene terephthalate (PAT), ethylenetetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend material, polyester Resin materials such as polyether ether ketone and polyamide, and resin materials using these as main raw materials. Furthermore, a resin material and an elastic material can be blended and used.

  As an elastic material, polyurethane, chlorinated polyisoprene, NBR, chloropyrene rubber, EPDM, hydrogenated polybutadiene, butyl rubber, silicone rubber, or the like can be used, or a material obtained by blending two or more kinds can be used. If necessary, a conductive agent imparting electronic conductivity or a conductive agent having ionic conductivity is added to the resin material and elastic material used for these base materials in combination of one kind or two or more kinds. Among these, it is preferable to use a polyimide resin in which a conductive agent is dispersed from the viewpoint of excellent mechanical strength. As the conductive agent, a conductive polymer such as carbon black, metal oxide, or polyaniline can be used.

  When a belt-shaped configuration such as the intermediate transfer belt 409 is employed as the intermediate transfer member, the thickness of the belt is generally preferably 50 to 500 μm and more preferably 60 to 150 μm, but is appropriately selected according to the hardness of the material. be able to.

  For example, a belt made of a polyimide resin in which a conductive agent is dispersed is 5 to 20% by mass as a conductive agent in a polyamic acid solution, which is a polyimide precursor, as described in JP-A-63-311263. After the carbon black is dispersed, the dispersion is cast on a metal drum and dried, and then the film peeled off from the drum is stretched at a high temperature to form a polyimide film. Can be produced.

  The film molding is generally performed by injecting a polyamic acid solution film-forming stock solution in which a conductive agent is dispersed into a cylindrical mold and, for example, heating at 100 to 200 ° C. at a rotational speed of 500 to 2000 rpm. The film was formed into a film by a centrifugal molding method while rotating, and then the obtained film was demolded in a semi-cured state and covered with an iron core. It can be carried out by proceeding a ring-closing reaction) and carrying out main curing. In addition, the stock solution is cast on a metal sheet to a uniform thickness and heated to 100 to 200 ° C. to remove most of the solvent in the same manner as described above, and then gradually raised to a high temperature of 300 ° C. or higher. There is also a method of forming a polyimide film. Further, the intermediate transfer member may have a surface layer.

  When a drum-shaped configuration is adopted as the intermediate transfer member, it is preferable to use a cylindrical substrate formed of aluminum, stainless steel (SUS), copper, or the like as the substrate. If necessary, an elastic layer can be coated on the cylindrical substrate, and a surface layer can be formed on the elastic layer.

  The transfer medium according to the present invention is not particularly limited as long as it is a medium that transfers a toner image formed on an electrophotographic photosensitive member. For example, when transferring directly from an electrophotographic photosensitive member to a transfer medium such as paper, paper or the like is the transfer medium. When an intermediate transfer member is used, the intermediate transfer member is a transfer medium.

  FIG. 8 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of a process cartridge including the electrophotographic photosensitive member of the present invention. In addition to the electrophotographic photosensitive member 207, the process cartridge 300 is provided with a charging device 208, a developing device 211, a cleaning device (cleaning means) 213, an opening 218 for exposure, and an opening 217 for static elimination exposure. Are combined and integrated with each other.

  The process cartridge 300 is detachably attached to an image forming apparatus main body including a transfer device 212, a fixing device 215, and other components (not shown), and the image forming apparatus together with the image forming apparatus main body. It constitutes.

  Since the image forming apparatus 220 and the process cartridge 300 described above include the electrophotographic photosensitive member of the present invention, toner can be sufficiently suppressed from remaining on the surface layer of the photosensitive member. Quality) image can be obtained, and the stability of the image quality can be improved.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Preparation of electrophotographic photoreceptor (1))
First, a 30 mmφ aluminum substrate roughened by a honing process was prepared.

  Next, 30 parts by mass of an organic zirconium compound (acetylacetone zirconium butyrate) and an organic silane were added to 170 parts by mass of n-butyl alcohol in which 4 parts by mass of polyvinyl butyral resin (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd., trade name) were dissolved. 3 parts by mass of a compound (γ-aminopropyltrimethoxysilane) was added and mixed and stirred to obtain a coating solution for forming an undercoat layer. This coating solution is dip-coated on the aluminum substrate and air-dried at room temperature for 5 minutes, and then the substrate is heated to 50 ° C. over 10 minutes to 50 ° C. and 85% RH (dew point 47 ° C.). It put in the constant temperature and humidity chamber, humidified for 20 minutes, and the hardening acceleration | stimulation process was performed. Then, it put into the hot air dryer and dried for 10 minutes at 170 degreeC, and obtained the undercoat layer.

  Next, at a Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum using Cu-kα rays as a charge generation material, 7.4 °, 16.6 °, 25.5 ° and 28.3 Gallium chloride phthalocyanine having a diffraction peak at a position of ° was prepared. And 15 parts by mass of this, a mixture obtained by mixing 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, Nippon Union Carbide, trade name) and 300 parts by mass of n-butyl alcohol, And dispersed for 4 hours. The obtained dispersion was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

Subsequently, 20 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and 20 parts by mass of N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine And 60 parts by mass of bisphenol Z polycarbonate resin (molecular weight 40,000) were sufficiently dissolved and mixed in a mixed solution of 280 parts by mass of tetrohydrofuran and 120 parts by mass of toluene. Next, 8 parts by mass of tetrafluoroethylene resin particles and 0.2 parts by mass of a fluorine-based graft polymer were further added to obtain a mixture. Then, the pressure of a high-pressure homogenizer (LA-33S, manufactured by Nanomizer Co., Ltd., trade name) is set to 500 kg / cm ² , and the mixture is dispersed by passing through the high-pressure homogenizer four times. A dispersion of resin particles was obtained. The obtained dispersion was dip-coated on the charge generation layer and dried to form a charge transport layer having a thickness of 26 μm to obtain an electrophotographic photoreceptor (1).

  When the cross section of the charge transport layer is observed using a transmission electron microscope (TEM) and analyzed by an image analyzer SPICCA (Nippon Avionics Co., Ltd., trade name), the tetrafluoroethylene resin particles are almost as primary particles. It was dispersed. Moreover, the average primary particle diameter was 0.2 micrometer, and all the observed tetrafluoroethylene resin particles were less than 1 micrometer in particle diameter irrespective of a primary particle or a secondary particle.

(Preparation of electrophotographic photoreceptor (2))
100 parts by mass of zinc oxide (average particle size 70 nm, manufactured by Teica) is stirred and mixed together with 450 parts by mass of toluene and 50 parts by mass of methanol, and 1.25 parts by mass of a silane coupling agent (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.). Was added and dispersed for 1 hour using a sand grinder mill. Thereafter, toluene was distilled off by distillation under reduced pressure, and after baking at 150 ° C. for 2 hours, it was cooled to room temperature and crushed to obtain surface-treated zinc oxide.

  Next, a mixed solution of 33 parts by mass of the surface-treated zinc oxide, 6 parts by mass of blocked isocyanate (Sumijoule 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd., trade name) and 25 parts by mass of methyl ethyl ketone was stirred and mixed for 30 minutes, and then a butyral resin ( BM-1, manufactured by Sekisui Chemical Co., Ltd., 5 parts by mass, silicone ball (Tospearl 120, manufactured by Toshiba Silicone Co., Ltd., product name) and 3 parts by weight and leveling agent (silicone oil SH29PA, manufactured by Toray Dow Corning Silicone Co., Ltd., product name) ) 0.01 part by mass was added to the above mixed solution, and a dispersion treatment was performed for 2 hours using a sand mill to obtain an undercoat layer coating solution. This coating solution was dip coated on a 30 mmφ aluminum substrate, dried at 160 ° C. for 100 minutes and cured to form an undercoat layer having a thickness of 20 μm.

  Next, 7.5 [deg.], 9.9 [deg.], 12.5 [deg.], And 16.3 at a Bragg angle (2 [theta] ± 0.2 [deg.]) Of an X-ray diffraction spectrum using Cu-k [alpha] rays as a charge generation material. Hydroxygallium phthalocyanine having diffraction peaks at positions of °, 18.6 °, 25.1 ° and 28.3 ° was prepared. Then, a mixture of 15 parts by mass of this, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide Co., Ltd., trade name) and 300 parts by mass of n-butyl alcohol was obtained using a sand mill. Time dispersed. The obtained dispersion was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm.

Subsequently, 20 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine and 20 parts by mass of N, N′-bis (3,4-dimethylphenyl) biphenyl-4-amine And 60 parts by mass of bisphenol Z polycarbonate resin (molecular weight 40,000) are sufficiently dissolved and mixed in a mixed solution of 280 parts by mass of Tetrohydrofuran and 120 parts by mass of toluene, and 8 parts by mass of tetrafluoroethylene resin particles; The mixture was obtained by adding 0.3 part by mass of a fluorine-based graft polymer. Then, the pressure of a high-pressure homogenizer (LA-33S, manufactured by Nanomizer Co., Ltd., trade name) is set to 500 kg / cm ² , and the mixture is dispersed by passing through the high-pressure homogenizer four times. A dispersion of resin particles was obtained. The obtained dispersion was applied onto the charge generation layer by dip coating and dried to form a charge transport layer having a thickness of 26 μm, whereby an electrophotographic photosensitive member (1) was obtained.

  When the cross section of the charge transport layer was observed using a transmission electron microscope (TEM) and analyzed by an image analyzer SPICCA (Nippon Avionics Co., Ltd., trade name), the tetrafluoroethylene resin particles were almost as primary particles. It was dispersed. Moreover, the average primary particle diameter was 0.2 micrometer, and all the observed tetrafluoroethylene resin particles were less than 1 micrometer in particle diameter irrespective of a primary particle or a secondary particle.

(Preparation of comparative electrophotographic photoreceptor (1))
A comparative electron was produced in the same manner as the production of the electrophotographic photosensitive member (1) except that the pressure of the high-pressure homogenizer used for dispersing the coating liquid (mixture) for forming the charge transport layer was changed to 200 kg / cm ^2. A photoconductor (1) was prepared. When the cross section of the charge transport layer was observed with a transmission electron microscope (TEM) and analyzed with an image analyzer SPICCA (Nippon Avionics Co., Ltd., trade name), the average particle size of the tetrafluoroethylene resin particles was 0. The content ratio of the primary particles and the secondary particles having a particle diameter of less than 1 μm was 75% with respect to the total number of primary particles and secondary particles of the tetrafluoroethylene resin particles.

(Preparation of comparative electrophotographic photoreceptor (2))
A comparative electrophotographic photoreceptor in the same manner as the photoreceptor (1) except that the coating liquid (mixture) for forming the charge transport layer was prepared without using the tetrafluoroethylene resin particles and the fluorine-based graft polymer. (2) was produced.

(Preparation of comparative electrophotographic photoreceptor (3))
Comparative electrophotographic photosensitive member (3) in the same manner as the preparation of the electrophotographic photosensitive member (1) except that the coating liquid (mixture) for forming the charge transport layer was prepared without using the tetrafluoroethylene resin particles. Was made.

(Preparation of developer)
First, 320 parts by mass of styrene, 80 parts by mass of n-butyl acrylate, 9 parts by mass of acrylic acid, 1.5 parts by mass of 1,10-decanediol diacrylate and 2.7 parts by mass of dodecanethiol were mixed and dissolved. Dissolved in 550 parts by mass of ion-exchanged water together with 4 parts by mass of an anionic surfactant, further dispersed and emulsified in a flask, and dissolved in 6 parts by mass of ammonium persulfate while stirring and mixing slowly for 10 minutes. 50 parts by mass of ion exchange water was added. Next, after the inside of the system was purged with nitrogen, the mixture in the flask was heated in an oil bath until the inside of the system reached 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours. Thus, a dispersion liquid (1) obtained by dispersing resin particles having an average particle diameter of 210 nm, a glass transition point of 51 ° C., and a weight average molecular weight (Mw) of 30000 was obtained.

  Next, 90 parts by mass of carbon black, 10 parts by mass of an anionic surfactant, and 240 parts by mass of ion-exchanged water are mixed and dispersed for 10 minutes using a homogenizer (UltraTurrax, IKA, trade name: T50). Then, it was subjected to a circulating ultrasonic disperser to obtain a colorant dispersion (1) in which a colorant having an average particle diameter of 155 nm was dispersed.

  Subsequently, 90 parts by mass of phthalocyanine, 10 parts by mass of an anionic surfactant, and 240 parts by mass of ion-exchanged water are mixed and dispersed under the same conditions as in the colorant dispersion (1), whereby the average particle size is 150 nm. A colorant dispersion (2) obtained by dispersing a colorant was obtained.

  In addition, 90 parts by weight of Pigment Red, 10 parts by weight of an anionic surfactant and 240 parts by weight of ion-exchanged water are mixed and dispersed under the same conditions as in the colorant dispersion (1), so that the average particle size is 170 nm. A colorant dispersion liquid (3) obtained by dispersing the colorant was obtained.

  Further, 90 parts by weight of Pigment Yellow, 10 parts by weight of an anionic surfactant and 240 parts by weight of ion-exchanged water are mixed and dispersed under the same conditions as in the colorant dispersion (1), whereby an average particle diameter is 175 nm. A colorant dispersion (4) obtained by dispersing the colorant as described above was obtained.

  Next, 90 parts by weight of polyethylene wax, 10 parts by weight of an anionic surfactant, and 240 parts by weight of ion-exchanged water were mixed and dispersed for 10 minutes using a homogenizer (UltraTurrax, IKA, trade name: T50). Dispersion treatment was performed with a pressure discharge type homogenizer to obtain a release agent dispersion liquid (1) obtained by dispersing a release agent having an average particle diameter of 200 nm.

  Subsequently, toner particles were prepared using each of the dispersions described above. First, 500 parts by mass of ion-exchanged water, 250 parts by mass of the dispersion (1), 36 parts by mass of the colorant dispersion (1), 56 parts by mass of the release agent dispersion (1), and a flocculant (polyaluminum chloride) 0. 5 parts by mass were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax, manufactured by IKA, trade name: T50). Thereafter, while stirring the inside of the flask in a heating oil bath, it was gently heated to 40 ° C. and held for 60 minutes, and further heated to 50 ° C. After maintaining at 50 ° C. for 60 minutes, it was confirmed by observation with an optical microscope that aggregated particles having an average particle diameter of 4.8 μm were formed. Further, the temperature of the heating oil bath was raised and held at 52 ° C. for 60 minutes. When the particle size was measured, it was confirmed that 5.0 μm aggregated particles were formed.

  60 mass parts of dispersion liquid (1) as a resin particle dispersion liquid was gradually added here. Further, the temperature of the heating oil bath was raised to 54 ° C. and held for 60 minutes. Thereby, it was confirmed that adhered particles having a particle diameter of 5.2 μm were formed.

  Then, after adding 1 mol / L sodium hydroxide aqueous solution so that pH might be set to 6.0, the said stainless steel flask is sealed, and it heats gently to 85 degreeC, continuing stirring using a magnetic seal. Hold for 60 minutes. Next, the mixture was further heated to 96 ° C., a 1 mol / L nitric acid aqueous solution was added until the pH became 5.0, and the mixture was held for 5 hours. Thereafter, the toner particles (1) were obtained by cooling, filtering, thoroughly washing with ion-exchanged water, and drying.

  Further, toner particles (2) were obtained in the same manner as in the preparation of the toner particles (1) except that the colorant dispersion (2) was used instead of the colorant dispersion (1) as a mixed component. In the toner particle (2) production process, the particle diameter of the adhered particles obtained upon completion of the adhesion process was measured to be 5.8 μm.

  Further, toner particles (3) were obtained in the same manner as in the preparation of toner particles (1) except that the colorant dispersion (3) was used instead of the colorant dispersion (1) as a mixed component. In the toner particle (3) production process, the particle diameter of the adhered particles obtained upon completion of the adhesion process was measured to be 5.1 μm.

  Further, toner particles (4) were obtained in the same manner as in the preparation of the toner particles (1) except that the colorant dispersion (4) was used instead of the colorant dispersion (1) as a mixed component. In the toner particle (4) production process, the particle diameter of the adhered particles obtained upon completion of the adhesion process was measured to be 5.3 μm.

  Further, 90 parts by mass of a polyester resin and 10 parts by mass of carbon black were kneaded with a Banbury mixer and then finely pulverized with a jet mill to prepare comparative toner particles. The particle size of the obtained comparative toner particles was measured and found to be 7.5 μm.

  By using the obtained toner particles (1) to (4) and comparative toner particles, 1 part by weight of hydrophobic silica is added to 100 parts by weight of each toner particle and mixed using a Henschel mixer. Toners (1) to (4) and a comparative toner were obtained, respectively.

  Next, a developer was prepared using the toner. First, 100 parts by mass of ferrite particles and 1.5 parts by mass of polymethylmethacrylate resin are placed in a pressure kneader together with 500 parts by mass of toluene, stirred and mixed at room temperature for 15 minutes, and further heated to 70 ° C. while being mixed under reduced pressure. Warm up. Thereafter, toluene was distilled off, followed by cooling and sieving using a 105 μm sieve to produce a ferrite-coated carrier. Then, the toners (1) to (4) and the comparative toner are respectively mixed with the ferrite-coated carrier, and the two-component developers (1) to (4) and the comparative developer having a toner concentration of 5% by mass. Was prepared.

(Image quality evaluation)
As shown in Table 1 below, developers (1) to (4) and a comparative developer, and electrophotographic photoreceptors (1) to (4) and comparative electrophotographic photoreceptors (1) to (3) are combined. Using a printer having the same structure as the Fuji Xerox full color printer DocuCenter Color 400 CP, a running test of 50000 sheets at an image density of 5% was performed in full color mode in an environment of 28 ° C. and 85% RH. did. The printer was modified so that the remaining untransferred toner on the mounted electrophotographic photosensitive member was collected by a blade cleaning method and returned to the developing device.

  The image quality of the solid part was visually evaluated for the image at the initial stage and at the time of 50000 sheets. These results are shown in Table 1 below. In Table 1, “density unevenness” means that streaky density unevenness appears in the solid portion.

1 is a schematic cross-sectional view showing a preferred embodiment of an electrophotographic photoreceptor of the present invention. It is a schematic cross section which shows another embodiment of the electrophotographic photoreceptor of this invention. FIG. 6 is a schematic cross-sectional view showing still another embodiment of the electrophotographic photosensitive member of the present invention. 3 is a TEM photograph taken of the surface layer of the electrophotographic photosensitive member of the present invention. 1 is a schematic configuration diagram illustrating a preferred embodiment of an image forming apparatus of the present invention. It is a schematic block diagram which shows another embodiment of the image forming apparatus of this invention. It is a schematic block diagram which shows another embodiment of the image forming apparatus of this invention. 1 is a schematic configuration diagram showing a preferred embodiment of a process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11,21 ... Electrophotographic photosensitive member, 2 ... Conductive substrate, 3, 13, 23 ... Photosensitive layer, 4 ... Undercoat layer, 5 ... Charge generation layer, 6 ... Charge transport layer (surface layer), 7 ... Protective layer (surface layer), 26 ... charge transport layer.

Claims (7)

An electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate,
The photosensitive layer includes a surface layer containing tetrafluoroethylene resin particles, a fluorine-based graft polymer, and a binder resin at a position farthest from the conductive substrate,
The average primary particle diameter of the tetrafluoroethylene resin particles is 0.1 to 0.3 μm,
The content ratio of primary particles of the tetrafluoroethylene resin particles and secondary particles having a particle diameter of less than 1 μm is 80% or more with respect to the total number of primary particles and secondary particles of the tetrafluoroethylene resin particles. An electrophotographic photosensitive member characterized by the above. A method for producing an electrophotographic photosensitive member, wherein a photosensitive layer comprising a plurality of layers including a surface layer provided at a position farthest from the conductive substrate is formed on a conductive substrate,
A mixing step of obtaining a mixture in which at least tetrafluoroethylene resin particles, a fluorine-based graft polymer, a binder resin, and an organic solvent are mixed;
A dispersion step of obtaining a dispersion in which the tetrafluoroethylene resin particles are dispersed by treating the mixture twice or more with a high-pressure homogenizer set at a pressure of 300 kg / cm ² or more and less than 700 kg / cm ² ;
See containing and a surface layer forming step of forming the surface layer of the photosensitive layer by drying by coating the dispersion liquid,
An average primary particle diameter of the tetrafluoroethylene resin particles contained in the surface layer is 0.1 to 0.3 μm, and primary particles of the tetrafluoroethylene resin particles and secondary particles having a particle diameter of less than 1 μm. A method for producing an electrophotographic photoreceptor , wherein the content is 80% or more based on the total number of primary particles and secondary particles of the tetrafluoroethylene resin particles . An electrophotographic photoreceptor according to claim 1 ;
A charging device for charging the electrophotographic photoreceptor;
An exposure apparatus that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image;
A developing device for developing the electrostatic latent image to form a toner image;
A transfer device for transferring the toner image to a transfer target;
A cleaning device for removing toner remaining on the electrophotographic photosensitive member;
An image forming apparatus comprising: The image forming apparatus according to claim 3 , further comprising a toner conveying device that supplies the toner removed by the cleaning device to the developing device. A charging step for charging the electrophotographic photosensitive member according to claim 1 ;
Exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; and
A developing step of developing the electrostatic latent image to form a toner image;
A transfer step of transferring the toner image to a transfer target;
A cleaning step of removing toner remaining on the electrophotographic photosensitive member;
An image forming method comprising: 6. The image forming method according to claim 5 , further comprising a toner conveying step of supplying the toner removed by the cleaning step to the developing device. An electrophotographic photoreceptor according to claim 1 ;
A charging device for charging the electrophotographic photosensitive member; an exposure device for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; a developing device for developing the electrostatic latent image to form a toner image; At least one selected from a cleaning device that removes toner remaining on the electrophotographic photosensitive member, and a toner transport device that supplies the toner removed by the cleaning device to the developing device;
A process cartridge comprising:

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