JP2007334326A - Coating liquid for forming photoreceptive layer and production method therefor, photoreceptor produced using the coating liquid, image forming apparatus using the photoreceptor, and electrophotographic cartridge using the photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable coating liquid for forming a photoreceptive layer having high productivity, and a production method of the coating liquid, and to moreover, provide a high-performance electrophotographic photoreceptor and an image forming apparatus which can produce high-quality images under various operating conditions without the manifestation of image defects, such as black spots, colored spots. <P>SOLUTION: In a method for preparing the coating liquid for forming the photoreceptive layer of an electrophotographic photoreceptor, containing a charge-generating material and a binder resin, a dispersion medium having a mean particle size of 1.0 to 350 μm is used as the dispersion medium for dispersing the charge generation material in the coating liquid for forming the photoreceptive layer. The coating liquid for forming the photoreceptive layer, prepared by the present method, is preferable for the formation of the photoreceptive layer of the electrophotographic photoreceptor. It is also preferable that a phthalocyanine pigment be used as the charge generation material, and that the 50% cumulative value (D50) of particle size distribution of the phthalocyanine pigment in the coating liquid be 0.13 μm or smaller when it is measured by the dynamic light-scattering method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coating solution for forming a photosensitive layer used when a photosensitive layer of an electrophotographic photoreceptor is applied and dried, a method for producing the same, a photoreceptor using the coating solution, and image formation using the photoreceptor. The present invention relates to an apparatus and an electrophotographic cartridge using the photoreceptor. The electrophotographic photosensitive member having a photosensitive layer formed by applying and drying the photosensitive layer forming coating solution of the present invention can be suitably used for electrophotographic printers, facsimiles, copying machines and the like.

  In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high quality images. For photoconductors that are the core of electrophotographic technology, organic photoconductors that use organic photoconductive materials that have the advantage of being non-polluting and easy to manufacture compared to inorganic photoconductive materials as photoconductive materials Has been developed. Usually, an organic photoreceptor has a photosensitive layer formed on a conductive support, but a so-called single-layer type photoreceptor having a single-layer photosensitive layer in which a photoconductive material is dissolved or dispersed in a binder resin. Also known is a so-called multilayer photoreceptor having a photosensitive layer composed of a plurality of layers in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated.

  A layer of an organic photoreceptor is usually formed by applying and drying a coating solution in which a material is dissolved or dispersed in various solvents because of its high productivity, and contains a charge generating material and a binder resin. In the charge generation layer, since the charge generation material and the binder resin exist in an incompatible state in the charge generation layer, the charge generation layer forming coating solution is formed by coating with a coating solution in which the charge generation material is dispersed. .

  Conventionally, such a coating liquid is produced by wet-dispersing a charge generating material in an organic solvent with a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill for a long time. (See, for example, Patent Document 1).

When the charge generation material in the coating solution for forming the charge generation layer is dispersed using a dispersion medium, the material of the dispersion medium is made of glass or zirconia to provide an electrophotographic photoreceptor excellent in electrical characteristics. Has been proposed (see, for example, Patent Document 2).
JP 2001-290292 A JP 2004-78140 A

  However, in the demand for image formation with higher image quality, a photoreceptor obtained by conventional electrophotographic technology is still poor in performance in various respects such as image quality and stability of a coating solution during production. There were enough points. Further, it is not always a good manufacturing method in terms of productivity.

  The present invention has been made in view of the background of the electrophotographic technology, and an object thereof is to provide a coating solution for forming a photosensitive layer having high productivity and stability, and a method for producing the same. . Another object of the present invention is to provide a high-performance electrophotographic photosensitive member that can form high-quality images even under various usage environments and that hardly causes image defects such as black spots and color spots. Still another object is to provide an image forming apparatus using the photoconductor and an electrophotographic cartridge using the photoconductor.

  As a result of intensive studies on the above problems, the present inventors can obtain a high-performance photosensitive layer forming coating solution by controlling the particle size of the charge generating material in the photosensitive layer forming coating solution containing the charge generating material within a specific range. As a dispersion medium used for dispersion at that time, a photosensitive medium with excellent stability in use by using a dispersion medium having a smaller particle diameter than that of a dispersion medium usually used. The present inventors have found a method for producing a coating liquid that can obtain a coating liquid for layer formation (the particle size of the charge generating material contained in the coating liquid is smaller than that of a known one) with high productivity. Furthermore, an electrophotographic photosensitive member having a photosensitive layer obtained by applying and drying the coating solution has good electrical characteristics even in different usage environments, and an image forming apparatus and an electrophotographic apparatus using the photosensitive member. According to the photoreceptor cartridge, it is possible to form a high-quality image, and it has been found that image defects such as black spots and color spots that are thought to be generated due to dielectric breakdown or the like are extremely difficult to develop, leading to the present invention. It was.

  That is, the first gist of the present invention is a method for producing a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member containing a charge generation material and a binder resin, wherein the charge generation material is dispersed in the coating solution for forming a photosensitive layer. In the method for producing a coating solution for forming a photosensitive layer, a dispersion medium having an average particle size in the range of 1.0 μm to 350 μm is used as the dispersion medium.

  The second gist of the present invention resides in a photosensitive layer forming coating solution produced by the above-described method for producing a photosensitive layer forming coating solution of the present invention.

  A third aspect of the present invention is a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member containing a charge generation material and a binder resin, wherein the charge generation material is a phthalocyanine pigment, and the phthalocyanine pigment in the coating solution The coating solution for forming a photosensitive layer is characterized in that a cumulative 50% particle diameter (D50) measured by a dynamic light scattering method is 0.13 μm or less.

  The fourth gist of the present invention resides in an electrophotographic photosensitive member having a photosensitive layer formed using the photosensitive layer forming coating solution of the present invention.

  The fifth gist of the present invention is that the electrophotographic photosensitive member of the present invention, a charging means for charging the electrophotographic photosensitive member, and image exposure is performed on the charged electrophotographic photosensitive member to form an electrostatic latent image. The image forming apparatus includes: an image exposing unit configured to develop a developing unit that develops the electrostatic latent image with toner; and a transfer unit configured to transfer the toner to a transfer target. In this image forming apparatus, it is preferable that the light used for the image exposure unit has a wavelength within a range of 350 nm to 600 nm.

  The sixth aspect of the present invention is to form an electrostatic latent image by performing image exposure on the electrophotographic photosensitive member of the present invention, a charging means for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member. Image exposing means, developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive member with toner, transfer means for transferring the toner to a transfer target, and the toner attached to the electrophotographic photosensitive member The electrophotographic photosensitive member cartridge includes at least one of cleaning means for recovering the toner.

  According to the method for producing a photosensitive layer forming coating solution of the present invention, the photosensitive layer forming coating solution of the present invention can be manufactured with high productivity and is in a stable state, gelled or dispersed charge. The generated material does not precipitate and can be stored and used for a long time. In addition, the coating solution has less change in physical properties such as viscosity at the time of use, and is continuously applied on a support and dried to form a photosensitive layer. The film thickness is uniform.

  Furthermore, the electrophotographic photoreceptor of the present invention has stable electrical characteristics even at low temperature and low humidity, and is excellent in electrical characteristics. According to the image forming apparatus using the electrophotographic photosensitive member of the present invention, it is possible to form a good image with extremely few image defects such as black spots and color points, and particularly, the image forming device is placed in contact with the electrophotographic photosensitive member. In an image forming apparatus charged by a charging unit, it is possible to form a good image with extremely few image defects such as black spots and color spots. Further, according to the image forming apparatus using the electrophotographic photosensitive member of the present invention and the light used for the image exposure means having a wavelength in the range of 350 nm to 600 nm, the initial charging potential and the sensitivity are high. A quality image can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.

[Coating liquid for forming photosensitive layer and its production method]
The method for producing a coating solution for forming a photosensitive layer according to the present invention includes a dispersion for dispersing a charge generating material in a coating solution for forming a photosensitive layer in the production of a coating solution for forming a photosensitive layer containing a charge generating material and a binder resin. As the medium, a dispersion medium having an average particle diameter of 1.0 μm to 350 μm is used. The manufactured coating solution for forming a photosensitive layer is a single layer type in which a dispersion medium is separated and removed, and a charge generation material and a binder resin are dispersed in the coating solution, and contains a charge generation material and a charge transport material. It is used as a “photosensitive layer forming coating solution” for forming a photosensitive layer, or as a “charge generating layer forming coating solution” for forming a laminated photosensitive layer in which a charge generating layer and a charge transport layer are laminated.

<Charge generation material>
The charge generating material constitutes a coating solution for forming a photosensitive layer, and various materials conventionally proposed for use as a photosensitive layer of an electrophotographic photoreceptor can be used. Examples of charge generation materials include azo pigments, phthalocyanine pigments, anthanthrone pigments, quinacridone pigments, cyanine pigments, pyrylium pigments, thiapyrylium pigments, indigo pigments, polycyclic quinone pigments, squaric acid. And pigments. Particularly preferred are phthalocyanine pigments or azo pigments. The phthalocyanine pigment can form an electrophotographic photosensitive member with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has sufficient sensitivity to white light and a laser beam having a relatively short wavelength. Each is excellent in that an electrophotographic photoreceptor can be formed.

  When a phthalocyanine pigment is used as the charge generation material, the above excellent effects are exhibited, which is preferable. Specific examples of the phthalocyanine pigment include metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, and other metals, or oxides, halides, hydroxides, alkoxides thereof, and the like. Mention may be made of coordinated phthalocyanine pigments of various crystal forms. In particular, oxytitanium phthalocyanines such as X-type and τ-type metal-free phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types, and oxyvanadium Phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, μ-oxo-aluminum phthalocyanine dimer such as type II A monomer is preferably used. Among these phthalocyanine pigments, A-type (β-type), B-type (α-type) and D-type (Y-type) oxytitanium phthalocyanines, II-type chlorogallium phthalocyanines, V-type hydroxygallium phthalocyanines, and G-types [Mu] -oxo-gallium phthalocyanine dimer and the like are particularly preferably used. Further, among these phthalocyanine pigments, oxytitanium phthalocyanine having a Bragg angle (2θ ± 0.2 °) of X-ray diffraction spectrum with respect to CuKα characteristic X-ray having a main diffraction peak of 27.3 °, 9.3 °, Oxytitanium phthalocyanine showing main diffraction peaks at 13.2, 26.2, and 27.1 °, with main diffraction peaks at 9.2, 14.1, 15.3, 19.7, 27.1 ° 6. Dihydroxysilicon phthalocyanine, dichlorotin phthalocyanine showing main diffraction peaks at 8.5 °, 12.2 °, 13.8 °, 16.9 °, 22.4 °, 28.4 ° and 30.1 °, 6. hydroxygallium phthalocyanine showing main diffraction peaks at 5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °; °, 16.6 °, chlorogallium phthalocyanine is preferably used having a diffraction peak at 25.5 ° and 28.3 °. Among these, oxytitanium phthalocyanine having a main diffraction peak at 27.3 ° is particularly preferably used. In this case, oxytitanium phthalocyanine having a main diffraction peak at 9.5 °, 24.1 °, and 27.3 ° is used. Especially preferably used.

  As the phthalocyanine pigment, only a single compound may be used, or it may be composed of several mixed states or mixed crystal states. The mixed state or mixed crystal state of the phthalocyanine pigments here may be those obtained by mixing the respective phthalocyanine pigments later, or in the production process or treatment process of the phthalocyanine pigments such as synthesis, pigmentation, and crystallization. It may be generated. Acid paste treatment, grinding treatment, solvent treatment, and the like are known as the treatment for obtaining a mixed state or a mixed crystal state. In order to produce a mixed crystal state, as described in JP-A-10-48859, after mixing two kinds of crystals, they are mechanically ground and made amorphous, and then a specific crystal state is obtained by solvent treatment. The method of converting into is mentioned.

  Further, when a phthalocyanine pigment is used as the charge generation material, a charge generation material other than the phthalocyanine pigment may be used in combination. For example, azo pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, indigo pigments, benzimidazole pigments, pyrylium salts, thiapyrylium salts, squalium salts, and the like can be used in combination.

Moreover, when using an azo pigment together, various well-known bisazo pigments and trisazo pigments are preferably used. Examples of preferred azo pigments are shown below. In the following general formula, Cp ¹ to Cp ³ represent a coupler.

The couplers Cp ¹ to Cp ³ preferably have the following structures. In the following structure, “*” represents a bonding position.

  In particular, examples of suitable azo compounds are shown below.

  The charge generating material is dispersed in the photosensitive layer forming coating solution, but may be pre-ground before being dispersed in the coating solution. The pre-pulverization can be performed using various pulverizers, but is usually performed using a pulverizer such as a ball mill or a sand grind mill. Any grinding media can be used as the grinding media to be fed into these grinding devices as long as the grinding media is not pulverized during the grinding treatment and can be easily separated after the dispersion treatment. However, it is preferable to use beads or balls such as glass, alumina, zirconia, stainless steel, and ceramics. In the pre-grinding, it is preferred to grind the volume average particle diameter to 500 μm or less, and more preferably to 250 μm or less. The volume average particle diameter may be measured by any method commonly used by those skilled in the art, but is usually measured by a sedimentation method or a centrifugal sedimentation method.

<Binder resin>
As the binder resin, a binder resin soluble in an organic solvent, which is usually used in a coating solution for forming a photosensitive layer of an electrophotographic photoreceptor, is used. When the photosensitive layer forming coating solution is a coating solution for forming the charge generation layer of the laminated photosensitive layer, when forming another layer on the formed charge generation layer, the binder resin to be used is There is no particular limitation as long as it is insoluble in the organic solvent contained in the coating solution forming the “other layer” or has low solubility and does not substantially mix.

  Examples of binder resins include polyvinyl butyral resins, polyvinyl formal resins, polyvinyl acetal resins such as partially acetalized polyvinyl butyral resins in which a part of butyral is modified with formal or acetal, polyarylate resins, polycarbonate resins, polyester resins , Modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane Resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, casein, vinyl chloride-vinyl acetate copolymer, hydroxy-modified Vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer such as vinyl chloride-vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer , Vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, insulating resins such as phenol-formaldehyde resins, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylperylene. It can be used by selecting from among them, but is not limited to these polymers. These binder resins may be used alone or in combination of two or more.

  Solvents or dispersion media used to dissolve the binder resin and prepare the coating liquid include, for example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, aromatic solvents such as toluene, xylene, and anisole, and chlorobenzene. Halogenated aromatic solvents such as dichlorobenzene and chloronaphthalene, amide solvents such as dimethylformamide and N-methyl-2-pyrrolidone, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol, glycerin , Aliphatic polyhydric alcohols such as polyethylene glycol, chain, branched, and cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, 4-methoxy-4-methyl-2-pentanone, methyl formate, ethyl acetate, n-acetate -Esthetics such as butyl Solvents, halogenated hydrocarbon solvents such as methylene chloride, chloroform, 1,2-dichloroethane, chain chains such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, and cyclic Ether solvents, acetonitrile, dimethyl sulfoxide, sulfolane, aprotic polar solvents such as hexamethylphosphate triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, nitrogen-containing compounds such as ethylenediamine, triethylenediamine, triethylamine, ligroin Mineral oil, water, etc. are mentioned. In particular, those which do not dissolve the undercoat layer described later are preferably used. These solvents or dispersion media can be used alone or in combination of two or more.

  In the case where the charge generation layer of the function-separated photosensitive layer (so-called laminated type photosensitive layer), which is formed by separating and laminating the charge generation material and the charge transport material, is formed with a coating solution, the binder resin and charge constituting the coating solution The blending ratio (by weight) with the generating material is in the range of 10 to 1000 parts by weight, preferably 30 to 500 parts by weight, with respect to 100 parts by weight of the binder resin. In this case, the thickness of the charge generation layer is usually 0.1 μm to 4 μm, preferably 0.15 μm to 0.6 μm. If the mixing ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to problems such as aggregation of the charge generation material. On the other hand, if the mixing ratio of the charge generation material is too low, Therefore, it is preferable to use within the above range.

  On the other hand, in the case where a single layer type photosensitive layer having a charge generation material and a charge transport material in the same layer is formed with a coating solution, the binder resin, the charge generation material, and the charge transport material constituting the coating solution are binder resins. The charge generation material is in a range of 0.2 to 100 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the binder resin. . In this case, the film thickness of the photosensitive layer is usually 1 μm to 40 μm, preferably 5 μm to 30 μm. If the mixing ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to problems such as aggregation of the charge generation material. On the other hand, if the mixing ratio of the charge generation material is too low, Therefore, it is preferable to use within the above range.

  Examples of the charge transport material used in the case of forming a single layer type photosensitive layer having the charge generation material and the charge transport material in the same layer with a coating solution include polyvinyl carbazole, polyvinyl pyrene, polyglycidyl carbazole, polyacenaphthylene. Polymer compounds such as pyrene, anthracene, etc .; heterocyclic compounds such as indole derivatives, imidazole derivatives, carbazole derivatives, pyrazole derivatives, pyrazoline derivatives, oxadiazole derivatives, oxazole derivatives, thiadiazole derivatives; Hydrazone compounds such as diethylaminobenzaldehyde-N, N-diphenylhydrazone, N-methylcarbazole-3-carbaldehyde-N, N-diphenylhydrazone; 5- (4- (di-p-tolylamino) benzylidene) -5H-diben (A, d) styryl compounds such as cycloheptene; triarylamine compounds such as p-tolyltolylamine; benzidine compounds such as N, N, N ′, N′-tetraphenylbenzidine; butadiene compounds; di- ( and triphenylmethane compounds such as p-ditolylaminophenyl) methane. Among these, a hydrazone derivative, a carbazole derivative, a styryl compound, a butadiene compound, a triarylamine compound, a benzidine compound, or a combination of them is preferably used. These charge transport materials may be used alone or in combination.

<Distributed media>
Although various media can be applied as the dispersion media, a dispersion media having a shape close to a true sphere is preferably used. For the dispersion medium, for example, the average particle diameter can be determined by sieving by a sieve described in JIS Z 8801: 2000 or the like, or by measuring by image analysis, and the density can be measured by Archimedes method. Specifically, for example, the average particle diameter and the sphericity can be measured by an image analyzer represented by LUZEX50 manufactured by Nireco Corporation.

  The average particle diameter of the dispersion medium is usually within the range of 1.0 μm to 350 μm, and particularly preferably within the range of 10 μm to 100 μm. Generally, dispersion media with a small particle size tend to give a uniform dispersion in a short time. However, if the particle size becomes too small, the mass of the dispersion media becomes too small and efficient dispersion may not be possible. .

The density of the dispersion medium is usually 5.5 g / cm ³ or more, preferably 5.9 g / cm ³ or more, more preferably 6.0 g / cm ³ or more. Generally, dispersion using a higher density dispersion medium tends to give a uniform dispersion in a shorter time. The upper limit of the density cannot be generally specified depending on the material of the dispersion medium, but is usually about 10 g / cm ³ in consideration of the usable material. The density of the dispersion medium can be measured by, for example, an immersion method or a gas volume method.

  The sphericity of the dispersion medium is preferably 1.08 or less, more preferably 1.07 or less.

  The material of the dispersion medium is insoluble in the coating solution for forming the photosensitive layer and has a specific gravity larger than that of the coating solution for forming the photosensitive layer, and reacts with the coating solution for forming the photosensitive layer. Any known dispersion medium can be used as long as it does not alter the liquid. Specifically, steel balls such as chrome balls (ball balls for ball bearings) and carbon balls (carbon steel balls); stainless steel balls; ceramic balls such as silicon nitride balls, silicon carbide, zirconia, and alumina; titanium nitride, carbonitride Examples include spheres coated with a film of titanium or the like, among which ceramic spheres are preferable, and zirconia beads are particularly preferable. More specifically, it is preferable to use zirconia fired beads, particularly zirconia fired beads described in Japanese Patent No. 3400836.

<Distribution method>
In the photosensitive layer forming coating solution containing the charge generating material and the binder resin, the charge generating material is dispersed in the coating solution. As a method of dispersing the charge generating material in the coating solution, a method of wet dispersion in an organic solvent using a known pulverizing apparatus or dispersing apparatus can be applied using the above-described dispersion medium. Known pulverizers and dispersers include, for example, known mechanical pulverizers such as ball mills, sand grind mills, planetary mills, roll mills, pebble mills, ball mills, sand mills, screen mills, gap mills, vibration mills, paint shakers, A dispersing device such as an attritor may be mentioned.

  Among these, those that can be dispersed by circulating the coating liquid are preferable, and wet stirring ball mills such as a sand mill, a screen mill, and a gap mill are preferably used from the viewpoints of dispersion efficiency, fineness of reached particle diameter, ease of continuous operation, and the like. . These mills may be either vertical or horizontal. The disc shape of the mill can be any plate type, vertical pin type, horizontal pin type or the like. Preferably, a liquid circulation type sand mill is used.

  As a wet stirring ball mill, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, the dispersion medium filled in the stator, A dispersion medium that is connected to the slurry discharge port by a pin, disk, or annular type rotor that stirs and mixes the slurry containing the charge generation material and the binder resin supplied from the slurry supply port and the slurry discharge port. And a separator for discharging the separated slurry from the slurry discharge port, and a shaft that rotates and drives the separator has a hollow shaft that communicates with the slurry discharge port. What has a discharge path is preferable.

  In addition, the separator preferably used here is provided so as to be rotatable, and is preferably of an impeller type and rotates integrally with the rotor or independently of the rotor. The dispersion medium and the slurry are separated by the action of centrifugal force generated by rotation of the separator.

  According to such a wet stirring ball mill, the slurry from which the dispersion medium is separated by the separator is discharged through the hollow discharge path of the shaft center. At this time, since centrifugal force does not act on the shaft center of the shaft, the slurry is discharged without kinetic energy. For this reason, if the said wet stirring ball mill is used, there exists an effect that a kinetic energy will not be discharge | released wastefully but useless power will not be consumed.

  Such a wet stirring ball mill may be horizontal or vertical, but in order to increase the filling rate of the dispersion medium, it is preferably vertical and a slurry discharge port is preferably provided at the upper end of the mill. Also, it is desirable to provide a separator above the filling level of the dispersion medium. When the slurry discharge port is provided at the upper end of the mill, the slurry supply port is provided at the bottom of the mill.

  In a preferred embodiment, the slurry supply port is constituted by a valve seat and a V-shaped, trapezoidal, or cone-shaped valve body that is fitted to the valve seat so as to be movable up and down and is capable of line contact with the edge of the valve seat. . By forming an annular slit between the edge of the valve seat and the V-shaped, trapezoidal or cone-shaped valve body so that the dispersion medium cannot pass through, the raw slurry is supplied, but the dispersion medium falls Can be prevented. Further, it is possible to widen the slit to raise the valve body to discharge the dispersion medium, or to lower the valve body to close the slit and seal the mill. Further, since the slit is formed by the edge of the valve body and the valve seat, there is an advantage that the particles in the raw material slurry are difficult to bite, and even if it is bitten, it is easy to come out vertically and hardly clog.

  Further, if the valve body is caused to vibrate up and down by the vibration means, the coarse particles caught in the slit can be pulled out from the slit, and the biting itself is difficult to occur. In addition, a shearing force is applied to the raw material slurry by the vibration of the valve body, the viscosity is lowered, and the amount of raw material slurry passing through the slit, that is, the supply amount can be increased. As vibration means for vibrating the valve body, in addition to mechanical means such as a vibrator, means for changing the pressure of compressed air acting on a piston integrated with the valve body, for example, a reciprocating compressor, intake / exhaust of compressed air An electromagnetic switching valve or the like for switching between can be used.

  Further, it is desirable to provide a screen for separating the dispersion medium and a product slurry take-out port at the bottom of such a wet stirring ball mill so that the product slurry remaining in the mill can be taken out after the dispersion treatment.

  That is, the vertical wet stirring ball mill includes a cylindrical vertical stator, a slurry supply port provided at the bottom of the stator, a slurry discharge port provided at the upper end of the stator, and a shaft supported at the upper end of the stator. A shaft that is rotationally driven by a driving means such as a motor, a dispersion medium that is fixed to the shaft and is filled in the stator, and the charge generation material and the binder resin that are supplied from the slurry supply port. A pin, disk or annular type rotor for stirring and mixing the slurry to be mixed, a separator provided near the slurry discharge port, for separating the dispersion medium from the slurry, and a bearing for supporting the shaft at the upper end of the stator It consists of a mechanical seal. In this vertical wet-type stirring ball mill, a taper-shaped notch that expands downward is formed on the lower side of the annular groove into which the O-ring that contacts the mating ring of the mechanical seal is fitted. preferable.

  According to such a wet stirring ball mill, a mechanical seal is provided at the upper end of the stator at the shaft center where the dispersion medium or slurry has little kinetic energy and above the liquid level, thereby providing a mating ring for the mechanical seal. And dispersion medium and slurry can be greatly reduced between the lower portion of the O-ring fitting groove.

  In addition, the lower portion of the annular groove into which the O-ring is fitted is expanded downward by cutting, and the clearance is widened. Therefore, the slurry and the dispersion medium are jammed and solidified due to clogging or solidification. This prevents the mating ring from following the seal ring smoothly and maintains the function of the mechanical seal. In addition, since the lower part of the fitting groove into which the O-ring is fitted has a V-shaped cross section and the whole is not thin, the strength is not impaired, and the holding function of the O-ring is also impaired. Absent.

  In the above-described wet stirring ball mill, the separator has two disks each provided with a blade fitting groove on the inner surface facing each other, a blade fitted in the fitting groove and interposed between the disks, and the blade interposed. It is preferable to have a supporting means for sandwiching the disc from both sides. In a preferred embodiment, the support means is composed of a shaft step that forms a stepped shaft and a cylindrical presser unit that fits the shaft and presses the disc, and a blade is interposed between the shaft step and the presser unit. The disc is supported from both sides.

  FIG. 1 is a cross-sectional view showing an example of a vertical wet stirring ball mill. In FIG. 1, the raw slurry is supplied to a wet stirring ball mill and pulverized by being stirred together with the dispersion medium in the mill, and then the dispersion medium is separated by a separator 14 and discharged through the shaft 15. In this way, the route is returned and circulated and crushed.

  As shown in detail in FIG. 1, the vertical wet-type stirring ball mill includes a stator 17 having a longitudinally cylindrical shape and a jacket 16 through which cooling water for cooling the mill is passed, and a shaft of the stator 17. The shaft 15 is positioned at the center and is rotatably supported at the upper part of the stator. The shaft 15 is provided with a mechanical seal, and the shaft center of the upper part is a hollow discharge passage 19, and the lower end of the shaft projects in the radial direction. A pin or disk-shaped rotor 21 provided, a pulley 24 that is fixed to the upper portion of the shaft and transmits driving force, a rotary joint 25 that is attached to the opening end of the upper end of the shaft, and the shaft 15 near the upper portion in the stator. A separator 14 for separating dispersed media to be fixed, and a raw material slurry supply port 26 provided at the bottom of the stator so as to face the shaft end of the shaft 15; It is attached on a grid screen support 27 that is installed in the product slurry outlet 29 provided at an eccentric position of the stator bottom, has the screen 28 for separating the dispersion medium.

  The separator 14 is composed of a pair of disks 31 fixed to the shaft 15 at a predetermined interval and a blade 32 connecting the disks 31. The separator 14 constitutes an impeller and rotates with the shaft 15 to enter between the disks. The centrifugal force is applied to the dispersion medium and the slurry, and the dispersion medium is blown outward in the radial direction due to the difference in specific gravity, while the slurry is discharged through the discharge path 19 of the shaft center of the shaft 15. The raw material slurry supply port 26 includes an inverted trapezoidal valve body 35 that fits up and down on a valve seat formed at the bottom of the stator, and a bottomed cylindrical body 36 that protrudes downward from the bottom of the stator. When the valve body 35 is pushed up by the supply, an annular slit is formed between the valve seat and the raw material slurry is supplied into the mill.

  The valve body 35 at the time of supplying the raw material slurry rises against the pressure in the mill by the supply pressure of the raw material slurry fed into the cylindrical body 36, and forms a slit between the valve seat.

  In order to eliminate clogging at the slit, the valve body 35 is repeatedly moved up and down to the upper limit position in a short cycle, and the biting can be eliminated by such vertical movement vibration. The vibration of the valve body 35 may be performed at all times or may be performed when a large amount of coarse particles are contained in the raw material slurry. In addition, when the supply pressure of the raw material slurry increases due to clogging, the valve body 35 is interlocked with this. You may do it.

  Specific examples of the wet stirring ball mill having such a structure include an ultra apex mill manufactured by Kotobuki Kogyo Co., Ltd.

  Next, a method for pulverizing the raw slurry will be described. The ball mill stator 17 is filled with a dispersion medium and driven by external power to rotate the rotor 21 and the separator 14, while a predetermined amount of raw slurry is sent to the slurry supply port 26, thereby the edge of the valve seat. The raw material slurry is supplied into the mill through a slit formed between the valve body 35 and the valve body 35.

  As the rotor 21 rotates, the raw material slurry and the dispersion medium in the mill are agitated and mixed, and the slurry is pulverized. Further, the dispersion medium and the slurry that have entered the separator are separated by the difference in specific gravity due to the rotation of the separator 14, and the dispersion medium having a high specific gravity is blown outward in the radial direction. It is discharged through the discharge path 19 formed in the heart and returned to the raw material tank. When the pulverization has progressed to some extent, the particle size of the slurry is appropriately measured. When the desired particle size is reached, the raw material pump is once stopped, then the mill operation is stopped, and the pulverization is terminated.

  When using such a vertical wet-stir ball mill to disperse the particulate charge generation material, it is preferable that the dispersion rate of the dispersion medium filled in the mill is pulverized at 50 to 100%. More preferably, it is 70 to 95%, and particularly preferably 80 to 90%.

  In the wet stirring ball mill applied to disperse the coating solution for forming a photosensitive layer according to the present invention, the separator may be a screen or a slit mechanism, but is preferably an impeller type and is preferably a vertical type. . It is desirable that the wet stirring ball mill be oriented vertically and the separator be provided at the top of the mill. Particularly, when the filling rate of the dispersion medium is set to 60 to 90%, the grinding is most efficiently performed, and the separator is disposed on the dispersion medium. It can be positioned above the filling level, and there is an effect that the dispersion medium can be prevented from being discharged on the separator.

  The operating conditions of the wet stirring ball mill applied to disperse the coating solution for forming the photosensitive layer according to the present invention are the volume average particle diameter of the charge generation material aggregate secondary particles in the coating solution, and the stability of the coating solution. The surface shape of the photosensitive layer (charge generation layer) formed by coating the coating solution, the characteristics of the electrophotographic photoreceptor having the photosensitive layer (charge generation layer) formed by coating the coating solution, Particularly, the supply speed of the coating liquid and the rotational speed of the rotor are particularly affected.

  The supply speed of the photosensitive layer forming coating solution is affected by the volume of the mill and the shape of the undercoat layer forming coating solution, because it depends on the residence time of the undercoat layer forming coating solution in the mill. A range of 20 kg / hour to 80 kg / hour per liter of volume (hereinafter sometimes abbreviated as L) is preferred, and a range of 30 kg / hour to 70 kg / hour per liter of mill volume is more preferred.

  In addition, when a charge generation material such as a phthalocyanine pigment is dispersed using a wet stirring ball mill, there is no limitation on the filling rate of the dispersion medium filled in the wet stirring ball mill, and the charge generation material has a desired particle size distribution. If dispersion can be performed up to, it is arbitrary. However, when the charge generating material is dispersed using the vertical wet stirring ball mill as described above, the filling rate of the dispersion medium filled in the wet stirring ball mill is usually 50% or more, preferably 70% or more, More preferably, it is 80% or more, usually 100% or less, preferably 95% or less, more preferably 90% or less.

  Further, the rotational speed of the rotor is affected by parameters such as the rotor shape and the gap with the stator, but in the case of a commonly used stator and rotor, the peripheral speed of the rotor tip is in the range of 5 m / second to 20 m / second. More preferably, it is in the range of 8 m / second to 15 m / second, and in particular, 10 m / second to 12 m / second.

  The dispersion medium is usually used in a volume ratio of 0.5 to 5 times with respect to the photosensitive layer forming coating solution. In addition to the dispersion medium, a dispersion aid that can be easily removed after dispersion can be used in combination. Examples of the dispersion aid include sodium chloride and sodium nitrate.

  The dispersion of the charge generation material is preferably carried out in the presence of a dispersion solvent in a wet manner, but a binder resin and various additives may be mixed at the same time. Although it does not restrict | limit especially as this solvent, If the organic solvent used for the coating liquid for undercoat layer formation is used, it will be unnecessary to pass processes, such as solvent exchange, after dispersion | distribution, and it is suitable. Any one of these solvents may be used alone, or two or more thereof may be used in combination as a mixed solvent.

  In particular, it is preferable that Y-type oxytitanium phthalocyanine or the like that easily undergoes crystal transformation is dispersed in the presence of a binder resin.

  From the viewpoint of productivity, the amount of the solvent used is usually 0.1 parts by weight or more, preferably 1 part by weight or more, and usually 500 parts by weight or less, preferably 1 part by weight or more based on 1 part by weight of the charge generation material to be dispersed. The range is 100 parts by weight or less. The temperature at the time of mechanical dispersion can be from the freezing point of the solvent (or mixed solvent) to the boiling point or less, but is usually in the range of 0 ° C. or more and 200 ° C. or less from the viewpoint of safety during production. It is done in. In particular, the above-described Y-type oxytitanium phthalocyanine has a low temperature, preferably 0 ° or more and 20 ° or less.

  After the dispersion treatment using the dispersion medium, it is preferable that the dispersion medium is separated and removed and further subjected to ultrasonic treatment. In the ultrasonic treatment, ultrasonic vibration is applied to the coating solution for forming the photosensitive layer, but there is no particular limitation on the vibration frequency and the like. Usually, ultrasonic vibration is generated by an oscillator having a frequency of 10 kHz to 40 kHz, preferably 15 kHz to 35 kHz. Add

  Although there is no restriction | limiting in particular in the output of an ultrasonic oscillator, Usually 100W-5kW thing is used. In general, it is better to disperse a small amount of coating liquid with ultrasonic waves from a small output ultrasonic oscillator than to process a large amount of coating liquid with ultrasonic waves from a high output ultrasonic oscillator. Therefore, the amount of the photosensitive layer forming coating solution to be processed at one time is preferably 1 to 50 L, more preferably 5 to 30 L, and particularly preferably 10 to 20 L. In this case, the output of the ultrasonic oscillator is preferably 200 W to 3 kW, more preferably 300 W to 2 kW, and particularly preferably 500 W to 1.5 kW.

  There is no particular limitation on the method of applying ultrasonic vibration to the coating liquid for forming the photosensitive layer, but the method of directly immersing the ultrasonic oscillator in the container containing the coating liquid, the ultrasonic oscillator on the outer wall of the container containing the coating liquid And a method of immersing a solution containing a coating solution in a liquid that has been vibrated by an ultrasonic transmitter.

  Among these methods, a method of immersing a solution containing a coating solution in a liquid subjected to vibration by an ultrasonic transmitter is preferably used. In this case, the liquid to be vibrated by the ultrasonic transmitter includes water; alcohols such as methanol; aromatic hydrocarbons such as toluene; and fats and oils such as silicone oil. In view of cleaning properties, it is preferable to use water. In the method of immersing a solution containing a coating liquid in a liquid that has been vibrated by an ultrasonic transmitter, the efficiency of ultrasonic treatment changes depending on the temperature of the liquid, so that the temperature of the liquid can be kept constant. preferable. The temperature of the liquid to which vibration is applied may increase due to the applied ultrasonic vibration. The temperature of the liquid is usually 5 to 60 ° C, preferably 10 to 50 ° C, and more preferably 15 to 40 ° C.

  As a container for storing the coating solution during the ultrasonic treatment, any container can be used as long as it is a container that is usually used to contain a coating solution used for forming a photosensitive layer for an electrophotographic photosensitive member. , A resin container such as polyethylene and polypropylene, a glass container, and a metal can. Among these, metal cans are preferable, and in particular, 18 liter metal cans as defined in JIS Z 1602 are preferably used. This is because it is hardly affected by organic solvents and is strong against impact.

  The coating solution for forming a photosensitive layer is used after being filtered as necessary in order to remove coarse particles. As the filtration media in this case, any filtration media such as cellulose fiber, resin fiber, glass fiber, etc., which are usually used for filtration may be used. As a form of the filtration media, a so-called wind filter in which various fibers are wound around a core material is preferable due to a large filtration area and high efficiency. As the core material, any conventionally known core material can be used, and examples thereof include a stainless steel core material and a resin core material that does not dissolve in a photosensitive layer forming coating solution such as polypropylene.

  The photosensitive layer forming coating solution produced in this way is used for forming a charge generation layer by further adding a binder or various auxiliary agents if desired. In addition, the method described in the item <Dispersion method> is very effective also in producing a coating liquid for forming an undercoat layer described later, and is preferably used in combination.

<Coating solution for forming photosensitive layer>
The coating solution for forming a photosensitive layer of the electrophotographic photosensitive member of the present invention is a dispersion processed by the dispersion method described above.

  Although it is desirable that the charge generation material in the coating solution for forming the photosensitive layer is present as primary particles, usually, such a phenomenon is rare, and it is present as aggregated secondary particles or both. Are often mixed. Therefore, how the particle size distribution should be in that state is very important. In particular, when the charge generation material is a phthalocyanine pigment, a cumulative 50% particle diameter (also referred to as a cumulative median diameter or a median diameter) D50 of a particulate charge generation material (hereinafter also referred to as a charge generation particle) in the coating liquid. It is preferably 0.13 μm or less. By setting this range, there is little precipitation of the charge generation particles and viscosity change in the coating solution, and as a result, the film thickness and surface properties after formation of the photosensitive layer become uniform. On the other hand, when the cumulative 50% particle diameter D50 measured by the dynamic light scattering method of the charge generation particles exceeds 0.13 μm, the precipitation and viscosity change of the charge generation particles in the coating solution are large, resulting in the photosensitive layer. Since the film thickness and surface properties after formation are not uniform, the quality is adversely affected. Further, the cumulative 50% particle size is preferably 0.12 μm or less. If the particle size is too fine, the interaction between the charge generating particles is lost. Therefore, the cumulative 50% particle size is preferably 0.02 μm or more, and more preferably 0.03 μm or more.

  The 90% cumulative particle diameter D90 of the charge generating material is preferably 0.25 μm or less. The absolute value of the difference (D90−D50) between the cumulative 90% particle diameter and the cumulative 50% particle diameter is preferably 0.10 μm or less, and more preferably 0.08 μm or less.

  In the present invention, the “cumulative 50% particle diameter” and “cumulative 90% particle diameter” of the charge generation material are the total of the charge generation particles as the charge generation material when the particle size distribution is measured by the dynamic light scattering method. When the cumulative curve of the volume particle size distribution is obtained from the small particle size side when the product is 100%, the particle diameter at the point where the cumulative curve is 50% is the cumulative 50% particle diameter, and the cumulative curve is 90%. The particle diameter of the points is defined as the cumulative 90% particle diameter.

  As long as the cumulative 50% particle diameter, the cumulative 90% particle diameter, and D90-D50 satisfy the above ranges, the present inventors have less gelation and viscosity change as a coating solution, and can be stored for a long time. As a result, it has been found that the film thickness and surface properties after forming the photosensitive layer are uniform. On the other hand, when the charge generation particles in the coating solution do not satisfy the above range, gelation and viscosity change in the coating solution are large, resulting in non-uniform film thickness and surface properties after forming the photosensitive layer. Therefore, the quality is adversely affected, which is not preferable.

  In the dynamic light scattering method, the speed of Brownian motion of finely dispersed particles is detected, and the particle size distribution is detected by irradiating the particles with laser light and detecting light scattering (Doppler shift) with different phases according to the speed. Is what you want. The value of the volume particle diameter of the charge generation particles in the coating liquid for forming a photosensitive layer of the present invention is a value when the charge generation particles are stably dispersed in the coating liquid, and the charge as the powder before dispersion is It does not mean the particle size of generated particles or wet cake. In the actual measurement, the cumulative 50% particle size D50 is specifically a dynamic light scattering particle size analyzer (manufactured by Nikkiso Co., Ltd., MICROTRAC UPA model: 9340-UPA, hereinafter abbreviated as UPA). The following settings were made. The specific measurement operation was performed based on the instruction manual of the particle size analyzer (manufactured by Nikkiso Co., Ltd., Document No. T15-490A00, revised No. E).

Measurement upper limit: 5.9978 μm
Measurement lower limit: 0.0035 μm
Number of channels: 44
Measurement time: 300 sec.
Particle permeability: Absorption Particle refractive index: N / A (not applicable)
Particle shape: Non-spherical Dispersion medium type: In the case of a phthalocyanine pigment, dimethoxyethane / 4-methoxy-4-methyl-2-pentanone = 9/1
Dimethoxyethane in the case of azo pigments Dispersion medium refractive index: 1.35
Density: 1.60 (g / cm ³ ; phthalocyanine pigment)
48 (g / cm ³ ; azo pigment)

  In addition, at the time of a measurement, it diluted with the dispersion solvent so that a sample concentration index | exponent (SIGNAL LEVEL) might be 0.6-0.8, and measured at 25 degreeC.

<Method for forming photosensitive layer>
The photosensitive layer (the charge generating layer in the case of a laminated photosensitive layer) is formed by dip coating or spraying the coating solution for forming a photosensitive layer of the present invention on a support, usually an undercoat layer formed on a conductive support. It is formed by applying and drying by a known application method such as application, nozzle application, spiral application, ring application, bar coat application, roll coat application, blade application or the like.

  Spray coating methods include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. Considering the degree of conversion, adhesion efficiency, etc., in the rotary atomizing electrostatic spray, the conveying method disclosed in the republished Japanese Patent Publication No. 1-805198, that is, the cylindrical workpiece is rotated while the axial direction is spaced. By continuously transporting the photosensitive layer, it is possible to obtain a photosensitive layer having an overall high adhesion efficiency and excellent film thickness uniformity.

  Examples of the spiral coating method include a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Laid-Open No. 52-119651, and paint from a minute opening disclosed in Japanese Patent Laid-Open No. 1-2231966. There are a method of continuously flying in a streak shape, a method using a multi-nozzle body disclosed in JP-A-3-193161, and the like.

  In the case of the dip coating method, the total solid concentration of the coating solution for forming a photosensitive layer is usually 1% by weight or more, preferably 2% by weight or more, and usually 10% by weight or less, preferably 5% by weight or less. The viscosity of the coating solution for forming a photosensitive layer is preferably 0.1 mPa · s or more, more preferably 0.5 mPa · s or more, and preferably 100 mPa · s or less, more preferably 20 mPa · s or less. And

  The surface shape of the coated photosensitive layer is characterized by in-plane root mean square roughness (RMS), in-plane arithmetic average roughness (Ra), and in-plane maximum roughness (P-V). These numerical values are numerical values obtained by extending the reference length of the root mean square height, arithmetic average height, and maximum height in the standard of JIS B 0601: 2001 to the reference plane. Using the value Z (x), the in-plane root mean square roughness (RMS) is the root mean square of Z (x), and the in-plane arithmetic mean roughness (Ra) is the absolute value of Z (x). The average in-plane roughness (P-V) represents the sum of the maximum value of the peak height of Z (x) and the maximum value of the valley depth. In the present invention, the in-plane root mean square roughness (RMS) of the photosensitive layer is usually in the range of 10 to 100 nm, preferably in the range of 20 to 50 nm. In the present invention, the in-plane arithmetic average roughness (Ra) of the photosensitive layer is usually in the range of 10 to 50 nm, preferably in the range of 10 to 50 nm. In the present invention, the in-plane maximum roughness (P-V) of the photosensitive layer is usually in the range of 100 to 1000 nm, preferably in the range of 300 to 800 nm.

  The numerical values of these surface shapes may be measured by any surface shape analyzer as long as they are measured by a surface shape analyzer capable of measuring irregularities in the reference plane with high accuracy. It is preferable to perform measurement by a method of detecting unevenness on the sample surface by combining a high-accuracy phase shift detection method and interference fringe order counting using an interference microscope. More specifically, it is preferable to measure in the wave mode by the interference fringe addressing method using Micromap of Ryoka System Co., Ltd.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor according to the present invention has a photosensitive layer formed using the above-described coating solution for forming a photosensitive layer on a conductive support. The formed photosensitive layer has improved sensitivity, improved adhesion to a conductive support (undercoat layer if it has an undercoat layer), improved nonuniformity in electrical characteristics, and prevention of surface potential drop due to repeated use. This layer has a function of preventing local surface potential fluctuations that cause image quality defects, and is an essential layer for the development of photoelectric characteristics.

  As the photosensitive layer constituting the electrophotographic photosensitive member of the present invention, any constitution applicable to a known electrophotographic photosensitive member can be adopted as long as it has a layer having a charge generation function. Specifically, for example, a so-called single layer type photosensitive layer having a single layer photosensitive layer in which a photoconductive material (charge generating material, charge transporting material, etc.) is dissolved or dispersed in a binder resin; containing a charge generating material And a so-called laminated photosensitive layer having a photosensitive layer composed of a plurality of layers formed by laminating a charge generating layer and a charge transporting layer containing a charge transporting material. In general, it is known that the photoconductive material exhibits the same performance as a function regardless of whether it is a single layer type or a laminated type. In the case of a single layer type, the entire photosensitive layer bears the charge generation layer.

  The photosensitive layer of the electrophotographic photosensitive member of the present invention may be in any known form, but in consideration of the mechanical properties, electrical characteristics, manufacturing stability, etc. of the photosensitive member, A photoconductor is preferred, and more preferred is a sequential lamination type photosensitive layer in which a charge generation layer, a charge generation layer, and a charge transport layer are laminated in this order on a conductive support.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a photosensitive layer (charge generating layer) containing a charge generating material and a binder resin on a conductive support. It is what has.

(1) The charge generation material is dispersed using a dispersion medium having an average particle size of 1.0 μm to 350 μm.
(2) The dispersion medium is zirconia beads.
(3) The dispersion method is performed using a ball mill.
(4) As a wet stirring ball mill, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and the dispersion medium filled in the stator And a rotor that stirs and mixes the slurry containing the charge generation material and the binder resin supplied from the slurry supply port, and is connected to the slurry discharge port, and is separated into a dispersion medium and a slurry by the action of centrifugal force. A wet-stirring ball mill having a separator that discharges the separated slurry from the slurry discharge port, wherein the shaft center that rotationally drives the separator has a hollow discharge path that communicates with the slurry discharge port. Obtained by the distributed processing used,
(5) As a wet stirring ball mill, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and the dispersion medium filled in the stator And a rotor that stirs and mixes the slurry containing the charge generation material and the binder resin supplied from the slurry supply port, and is connected to the slurry discharge port, and is separated into a dispersion medium and a slurry by the action of centrifugal force. A wet stirring ball mill having a separator that discharges the separated slurry from the slurry discharge port, the separator having two blades having fitting grooves of blades on opposing inner surfaces, and the fitting A blade fitted in a groove and interposed between the disks, and a support for sandwiching the disk with the blades interposed from both sides Obtained by the dispersion treatment using a ball mill having a stage,
(6) The cumulative 50% particle diameter D50 of the charge generation material (phthalocyanine pigment) in the coating solution measured by the dynamic light scattering method is 0.13 μm or less.

<Conductive support>
As the conductive support, for example, a metal material such as aluminum, aluminum alloy, stainless steel, copper, nickel, or a resin material imparted with conductivity by adding conductive powder such as metal, carbon, tin oxide, Mainly used are resin, glass, paper, or the like obtained by depositing or coating a conductive material such as aluminum, nickel, or ITO (indium-tin oxide) on its surface. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive material having an appropriate resistance value may be coated on a conductive support made of a metal material for controlling conductivity, surface property, etc., or for covering defects.

  When a metal material such as an aluminum alloy is used as the conductive support, it may be used after anodizing. When the anodizing treatment is performed, it is desirable to perform a sealing treatment by a known method.

For example, an anodic oxidation film is formed by anodizing in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc., but anodizing in sulfuric acid gives better results. . In the case of anodic oxidation in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / L, the dissolved aluminum concentration is 2 to 15 g / L, the liquid temperature is 15 to 30 ° C., the electrolysis voltage is 10 to 20 V, and the current density is 0.5 to it is preferably in the range of 2A / dm ^2, but not limited to the above conditions.

  It is preferable to perform a sealing treatment on the anodic oxide film thus formed. The sealing treatment may be performed by a known method. For example, it is immersed in an aqueous solution containing nickel fluoride as a main component, or immersed in an aqueous solution containing nickel acetate as a main component. A high temperature sealing treatment is preferably performed.

  Although the density | concentration of the nickel fluoride aqueous solution used in the case of the said low temperature sealing process can be selected suitably, when it is used in the range of 3-6 g / l, a more preferable result is obtained. In order to smoothly proceed with the sealing treatment, the treatment temperature is usually 25 ° C. or higher, preferably 30 ° C. or higher, and usually 40 ° C. or lower, preferably 35 ° C. or lower, and a nickel fluoride aqueous solution. The pH is usually 4.5 or higher, preferably 5.5 or higher, and usually 6.5 or lower, preferably 6.0 or lower. As the pH adjuster, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia and the like can be used. The treatment time is preferably in the range of 1 to 3 minutes per 1 μm of film thickness. In order to further improve the physical properties of the film, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant or the like may be added to the nickel fluoride aqueous solution. Subsequently, it is washed with water and dried to finish the low temperature sealing treatment.

  As the sealing agent in the case of the high-temperature sealing treatment, an aqueous solution of a metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt, and barium nitrate can be used, and it is particularly preferable to use nickel acetate. . The concentration in the case of using an aqueous nickel acetate solution is preferably in the range of 5 to 20 g / L. The treatment temperature is usually 80 ° C. or higher, preferably 90 ° C. or higher, and usually 100 ° C. or lower, preferably 98 ° C. or lower, and the pH of the nickel acetate aqueous solution is in the range of 5.0 to 6.0. It is preferable to process. Here, ammonia water, sodium acetate, etc. can be used as a pH adjuster. The treatment time is 10 minutes or longer, preferably 15 minutes or longer. In this case as well, sodium acetate, organic carboxylic acid, anionic and nonionic surfactants may be added to the nickel acetate aqueous solution in order to improve the film properties. Furthermore, you may process by the high temperature water or high temperature steam which does not contain salt substantially. Subsequently, it is washed with water and dried to finish the high temperature sealing treatment.

  When the average film thickness of the anodic oxide coating is thick, strong sealing conditions are required due to high concentration of the sealing liquid and high temperature / long time treatment. Accordingly, productivity is deteriorated and surface defects such as spots, dirt, and dusting are likely to occur on the coating surface. From such a point, it is preferable that the average film thickness of the anodic oxide coating is usually 20 μm or less, particularly 7 μm or less.

  The surface of the conductive support may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the conductive support. In addition, as a conductive support, it is possible to use a drawn tube as it is without cutting for cost reduction. Especially when using non-cutting aluminum supports such as drawing, impact processing, ironing, etc., the process eliminates dirt, foreign matter, etc. on the surface, small scratches, etc., and a uniform and clean support can be obtained. Therefore, it is preferable.

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer in order to improve adhesion and blocking properties. As the undercoat layer, a resin alone or a material in which particles of a metal oxide or the like are dispersed in a resin is used. The undercoat layer may be a single layer or a plurality of layers.

  Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used in an arbitrary combination and ratio. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicone. Any one of these treatments may be used, or two or more thereof may be applied. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. In addition, the titanium oxide particles may have only one crystal type, or two or more crystal types may be included in any combination and ratio.

  As the particle size of the metal oxide particles, various types can be used. Among them, the average primary particle size is usually 10 nm or more from the viewpoint of the properties of the binder resin and the like which are raw materials for the undercoat layer and the stability of the liquid. Usually, it is 100 nm or less, preferably 50 nm or less. This average primary particle size was obtained from a TEM photograph.

  The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride resin. Vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, cellulose such as nitrocellulose Ester resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconi Organic zirconium compounds of the arm alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanyl alkoxide compound, silane coupling agent, and the like. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamide, modified polyamide, and the like are preferable because they exhibit good dispersibility and coating properties.

  In particular, among these polyamide resins, a copolymerized polyamide resin containing a diamine represented by the following general formula (1) as a constituent component is particularly preferably used.

In General formula (1), R < ⁴ > -R < ⁷ > represents a hydrogen atom or an organic substituent. m and n each independently represents an integer of 0 to 4, and when there are a plurality of substituents, the substituents may be different from each other. The organic substituent represented by R ^{4 to} R ⁷ is preferably a hydrocarbon group having 20 or less carbon atoms, which may contain a hetero atom, and more preferably a methyl group, an ethyl group, or an n-propyl group. Alkyl groups such as isopropyl group; alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group; aryl groups such as phenyl group, naphthyl group, anthryl group, pyrenyl group, etc., more preferably alkyl group A group or an alkoxy group, and particularly preferably a methyl group or an ethyl group.

  The copolymerized polyamide resin containing the diamine represented by the general formula (1) as a constituent component is, for example, lactams such as γ-butyrolactam, ε-caprolactam, lauryllactam; 1,4-butanedicarboxylic acid, 1 , 12-dodecanedicarboxylic acid, 1,20-eicosanedicarboxylic acid and other dicarboxylic acids; 1,4-butanediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecanediamine, etc. Diamines: those obtained by combining piperazine and the like and copolymerized into binary, ternary, quaternary, and the like. Although there is no limitation in particular about this copolymerization ratio, Usually, the diamine component represented by the said General formula (1) is 5-40 mol%, Preferably it is 5-30 mol%.

  The number average molecular weight of the copolymerized polyamide resin is preferably 10,000 to 50,000, particularly preferably 15,000 to 35,000. If the number average molecular weight is too small or too large, it is difficult to maintain the uniformity of the film. There is no particular limitation on the method for producing the copolymerized polyamide resin, and an ordinary polyamide resin polycondensation method is appropriately applied, and a melt polymerization method, a solution polymerization method, an interfacial polymerization method, or the like is used. Further, in the polymerization, a monobasic acid such as acetic acid or benzoic acid, a monoacid base such as hexylamine or aniline, or a molecular weight regulator may be added. In the polymerization, a heat stabilizer represented by sodium phosphite, sodium hypophosphite, phosphorous acid, hypophosphorous acid and hindered phenol, and other polymerization additives can be added.

  Specific examples of the copolymerized polyamide resin preferably used for the undercoat layer are shown below. However, in specific examples, the copolymerization ratio represents the charge ratio (molar ratio) of the monomer.

  The mixing ratio of the metal oxide particles to the binder resin used for the undercoat layer can be arbitrarily selected, but it is usually applied in the range of 10 to 500 parts by weight with respect to 100 parts by weight of the binder resin. It is preferable in terms of liquid stability and coatability.

  The thickness of the undercoat layer can be arbitrarily selected, but is usually 0 from the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and applicability at the time of manufacture of the electrophotographic photosensitive member. 0.01 μm or more, preferably 0.1 μm or more, and usually 30 μm or less, preferably 20 μm or less is desirable.

  The undercoat layer may contain pigment particles, resin particles, and the like for the purpose of preventing image defects.

  The coating liquid used for forming the undercoat layer has a volume average diameter Mv measured by a dynamic light scattering method of 0.1 μm or less, and a volume average diameter Mv and a number average diameter Mp. It is preferable that the metal oxide particles satisfy the ratio Mv / Mp satisfying 1.10 ≦ Mv / Mp ≦ 1.40.

  It is more preferable that Mv / Mp satisfies the following formula.

  Whatever the volume average particle diameter Mv and number average diameter Mp of the metal oxide particles defined here, the particle diameter of the coating liquid for forming the undercoat layer is directly determined by the dynamic light scattering method. This is a value obtained by measurement.

  In the dynamic light scattering method, the speed of Brownian motion of finely dispersed particles is detected, and the particle size distribution is detected by irradiating the particles with laser light and detecting light scattering (Doppler shift) with different phases according to the speed. Is what you want. The value of the volume particle diameter of the metal oxide particles in the coating liquid for forming the undercoat layer is a value when the particles are stably dispersed in the coating liquid, and the metal oxide particles as powder before dispersion Does not mean the particle size of the wet cake. In actual measurement, the volume average diameter Mv and the number average diameter Mp described above are specifically a dynamic light scattering particle size analyzer (manufactured by Nikkiso Co., Ltd., MICROTRAC UPA model: 9340-UPA, hereinafter abbreviated as UPA). The following settings were used. The specific measurement operation was performed based on the instruction manual of the particle size analyzer (manufactured by Nikkiso Co., Ltd., Document No. T15-490A00, revised No. E).

Measurement upper limit: 5.9978 μm
Measurement lower limit: 0.0035 μm
Number of channels: 44
Measurement time: 300 sec.
Particle permeability: Absorption Particle refractive index: N / A (not applicable)
Particle shape: non-spherical density: 4.20 (g / cm ³ ) (*)
Dispersion medium type: Methanol / 1-propanol = 7/3
Dispersion medium refractive index: 1.35

  (*) This is a case of titanium dioxide particles, and in the case of other particles, the numerical values described in the instruction manual were used. In addition, at the time of a measurement, it diluted with the mixed solvent of methanol / 1-propanol = 7/3 so that a sample concentration index | exponent (SIGNAL LEVEL) might be 0.6-0.8, and measured at 25 degreeC.

  The volume average diameter Mv is a value obtained from the result of the particle size distribution of the particles obtained by the above measurement by the following formula (A), and the number average diameter Mp is also obtained by the following formula (B). . In the following, n represents the number of particles, v represents the particle volume, and d represents the particle diameter.

  In general, the coating solution for forming the undercoat layer contains metal oxide particles, and the metal oxide particles are dispersed in the coating solution for forming the undercoat layer. In order to disperse the metal oxide particles in the coating solution, for example, it is produced by wet dispersion in an organic solvent with a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill. However, as in the case of the method for producing the photosensitive layer forming coating solution, it is preferable to disperse using a dispersion medium.

  As a dispersing device for dispersing using a dispersion medium, any known dispersing device may be used. Pebble mill, ball mill, sand mill, screen mill, gap mill, vibration mill, paint shaker, atomizer Examples include lighters. Among these, those that can circulate and disperse the coating liquid for forming the undercoat layer are preferable. From the viewpoint of dispersion efficiency, fineness of the reached particle diameter, ease of continuous operation, etc., a wet stirring ball mill such as a sand mill, a screen mill, A gap mill is used. These mills may be either vertical or horizontal. The disc shape of the mill can be any plate type, vertical pin type, horizontal pin type or the like. Preferably, a liquid circulation type ball mill is used. This liquid-circulating ball mill is the same as that described in the section “Dispersion method” in the above “photosensitive layer forming coating solution and method for producing the same”.

  Also in the case of the undercoat layer forming coating solution, it is preferable to use the same liquid circulation type dispersion method and the same dispersing medium as those of the photosensitive layer forming coating solution described above.

  There is no particular limitation on the method of applying ultrasonic vibration to the coating solution for forming the undercoat layer, but there is a method in which an ultrasonic oscillator is directly immersed in a container containing the coating solution, and the outer wall of the container containing the coating solution is super Examples thereof include a method of bringing a sound wave oscillator into contact, a method of immersing a solution containing the coating liquid in a liquid that has been vibrated by an ultrasonic wave transmitter, and the like. Among these methods, a method of immersing a solution containing the coating solution in a liquid subjected to vibration by an ultrasonic transmitter is preferably used. In this case, the liquid to be vibrated by the ultrasonic transmitter includes water; alcohols such as methanol; aromatic hydrocarbons such as toluene; and fats and oils such as silicone oil. In view of cleaning properties, it is preferable to use water. In the method of immersing the solution containing the coating liquid in a liquid that has been vibrated by an ultrasonic transmitter, the efficiency of ultrasonic treatment changes depending on the temperature of the liquid, so the temperature of the liquid is kept constant. Is preferred. The temperature of the liquid to which vibration is applied may increase due to the applied ultrasonic vibration. The temperature of the liquid is usually 5 to 60 ° C, preferably 10 to 50 ° C, and more preferably 15 to 40 ° C.

  As a container for storing an undercoat layer forming coating solution during ultrasonic treatment, a container usually used for containing an undercoat layer forming coating solution used for forming an undercoat layer for an electrophotographic photosensitive member. Any container may be used as long as it is a resin container such as polyethylene or polypropylene, a glass container, or a metal can. Among these, metal cans are preferable, and in particular, 18 liter metal cans as defined in JIS Z 1602 are preferably used. This is because it is hardly affected by organic solvents and is strong against impact.

  The coating solution for forming the undercoat layer is used after being filtered as necessary in order to remove coarse particles. As the filtration media in this case, any filtration media such as cellulose fiber, resin fiber, glass fiber, etc., which are usually used for filtration may be used. As a form of the filtration media, a so-called wind filter in which various fibers are wound around a core material is preferable due to a large filtration area and high efficiency. As the core material, any conventionally known core material can be used. Examples of the core material include a stainless steel core material and a resin core material that does not dissolve in a coating solution for forming an undercoat layer such as polypropylene.

  The coating solution for forming the undercoat layer thus produced is used for forming the undercoat layer by further adding a binder or various auxiliary agents if desired.

  The undercoat layer is applied by a known application method such as dip coating, spray coating, nozzle coating, spiral coating, ring coating, bar coating coating, roll coating coating, blade coating, etc., on the support. And formed by drying.

  Spray coating methods include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. Considering the degree of conversion, adhesion efficiency, etc., in the rotary atomizing electrostatic spray, the conveying method disclosed in the republished Japanese Patent Publication No. 1-805198, that is, the cylindrical workpiece is rotated while the axial direction is spaced. By continuously transporting the electrophotographic photosensitive member, an electrophotographic photosensitive member excellent in film thickness uniformity can be obtained with a comprehensively high adhesion efficiency.

  Examples of the spiral coating method include a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Laid-Open No. 52-119651, and paint from a minute opening disclosed in Japanese Patent Laid-Open No. 1-2231966. There are a method of continuously flying in a streak shape, a method using a multi-nozzle body disclosed in JP-A-3-193161, and the like.

  In the case of the dip coating method, the total solid concentration of the coating solution for forming the undercoat layer is usually 1% by weight or more, preferably 10% by weight or more, and usually 50% by weight or less, preferably 35% by weight or less. The viscosity is preferably 0.1 mPa · s or more, and preferably 100 mPa · s or less.

  The coated film after coating is dried, but the drying temperature and time are adjusted so that necessary and sufficient drying is performed. The drying temperature is usually 100 to 250 ° C, preferably 110 ° C to 170 ° C, more preferably 115 ° C to 140 ° C. As a drying method, a hot air dryer, a steam dryer, an infrared dryer, and a far infrared dryer can be used.

<Photosensitive layer>
The photosensitive layer is formed by applying and drying the photosensitive layer forming coating solution of the present invention on the above-mentioned conductive support (on the undercoat layer when the above-mentioned undercoat layer is provided). As for the type of the photosensitive layer, the charge generation material and the charge transport material are present in the same layer and they are dispersed in a binder resin (single layer type photosensitive layer), and the charge generation material is a binder resin. A layered structure (laminated photosensitive layer) composed of two or more layers, including a charge generation layer dispersed therein and a charge transport layer in which a charge transport material is dispersed in a binder resin. It may be a form. Since the photosensitive layer forming coating solution of the present invention contains a charge generating material, in the case of a single layer type photosensitive layer, it is further prepared to contain a charge transporting material to form a photosensitive layer. In the case of a laminated photosensitive layer, it is used to form a charge transport layer.

  In addition, as the laminated photosensitive layer, a charge generation layer and a charge transport layer are laminated in this order from the conductive support side, and a charge transport layer and a charge generation layer are laminated in this order. Although a reverse lamination type photosensitive layer is mentioned, any form can be adopted.

<Layer containing charge generation material>
(Laminated photosensitive layer)
When the photosensitive layer is a so-called multilayer photosensitive layer, the layer containing the charge generation material is usually a charge generation layer, but the charge generation material may be contained in the charge transport layer. When the layer containing the charge generation material is a charge generation layer, the amount of the charge generation material is usually 30 to 500 parts by weight with respect to 100 parts by weight of the binder resin contained in the charge generation layer, More preferably, it is the range of 50-300 weight part. When the blending amount of the charge generating material with respect to the binder resin is too small, the electrical characteristics as an electrophotographic photosensitive member are not sufficient, and when the blending amount is too small, the stability of the coating solution is impaired. The volume average particle diameter of the charge generation material in the layer containing the charge generation material is preferably 1 μm or less, more preferably 0.5 μm or less. The film thickness of the charge generation layer is usually 0.1 μm to 2 μm, preferably 0.15 μm to 0.8 μm. For the charge generation layer, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersion stability, coating May contain leveling agents, surfactants, silicone oils, fluorine oils and other additives for improving the properties.

(Single layer type photosensitive layer)
When the photosensitive layer is a so-called single-layer type photosensitive layer, the above-mentioned “photosensitive layer forming coating solution” is contained in a matrix mainly composed of a binder resin and a charge transport material having the same mixing ratio as the charge transport layer described later. The charge generating material described in the column “is dispersed. In this case, the particle size and blending amount of the charge generating material are the same as those described in the same column. In this single-layer type photosensitive layer, since the matrix serves as both a charge generation layer and a charge transport layer, the coating solution for forming this matrix is included in the coating solution for forming a photosensitive layer of the present invention.

  If the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained. If the amount is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. It is used in the range of 50% by weight, more preferably in the range of 10 to 45% by weight. The film thickness of the photosensitive layer is usually 5 to 50 μm, more preferably 10 to 45 μm. In addition, single-layer type photosensitive layers are also known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, and dispersion aids for improving dispersion stability. Agents, leveling agents for improving coating properties, surfactants, silicone oils, fluorine oils and other additives may be contained.

<Layer containing charge transport material>
In the case of a so-called laminated photosensitive layer, the charge transport layer may be formed of a resin having a charge transport function alone, but a structure in which the following charge transport material is dispersed or dissolved in a binder resin is more preferable. On the other hand, in the case of a so-called single layer type photosensitive layer, a structure in which the following charge transporting material is dispersed or dissolved in a binder resin is used as a matrix in which the charge generating material is dispersed.

  Examples of the charge transport material include polymer compounds such as polyvinyl carbazole, polyvinyl pyrene, polyglycidyl carbazole and polyacenaphthylene; polycyclic aromatic compounds such as pyrene and anthracene; indole derivatives, imidazole derivatives, carbazole derivatives and pyrazole derivatives. , Heterocyclic compounds such as pyrazoline derivatives, oxadiazole derivatives, oxazole derivatives, thiadiazole derivatives; p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N-methylcarbazole-3-carbaldehyde-N, N-diphenylhydrazone, etc. Hydrazone compounds; styryl compounds such as 5- (4- (di-p-tolylamino) benzylidene) -5H-dibenzo (a, d) cycloheptene; triarylamines such as p-tolylamine System compound; N, N, N ', N'- benzidine compound of tetraphenyl benzidine; butadiene compounds; di - (p-ditolylaminophenyl) triphenylmethane compounds, such as methane, and the like. Among these, a hydrazone derivative, a carbazole derivative, a styryl compound, a butadiene compound, a triarylamine compound, a benzidine compound, or a combination of them is preferably used. These charge transport materials may be used alone or in combination.

  Examples of the binder resin used in the layer containing the charge transport material include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyarylate, polyester, polyester carbonate, polysulfone, Examples thereof include polyimide, phenoxy, epoxy, and silicone resin, and these partially crosslinked cured products can also be used.

  In addition, the layer containing the charge transport material contains various additives such as antioxidants such as hindered phenols and hindered amines, ultraviolet absorbers, sensitizers, leveling agents and electron-withdrawing substances as necessary. May be. The thickness of the layer containing the charge transport material is usually 5 to 60 μm, preferably 10 to 45 μm, more preferably 15 to 27 μm.

  The ratio of the binder resin to the charge transport material is usually 20 to 200 parts by weight, preferably 30 to 150 parts by weight, more preferably 40 to 120 parts by weight, based on 100 parts by weight of the binder resin. Used in the range of

<Surface layer>
For example, a surface protective layer or an overcoat layer mainly composed of a thermoplastic or thermosetting polymer may be provided as the outermost surface layer.

<Method for forming each layer>
Each of the layers constituting the electrophotographic photosensitive member is obtained by, for example, dip coating method, spraying, etc., obtained by dissolving or dispersing a substance to be contained in a layer in a solvent like the coating solution for forming a photosensitive layer of the present invention. They are sequentially applied and formed using a known method such as a coating method or a ring coating method. In this case, various additives such as a leveling agent, an antioxidant, and a sensitizer for improving coating properties may be included as necessary.

  As the organic solvent used for preparing the coating solution, the solvent that can be used for the wet mechanical dispersion can be used. Preferred examples include alcohols such as methanol, ethanol, propanol, cyclohexanone, 1-hexanol and 1,3-butanediol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; dioxane, tetrahydrofuran and ethylene glycol Ethers such as monomethyl ether; ether ketones such as 4-methoxy-4-methyl-2-pentanone; (halo) aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene; esters such as methyl acetate and ethyl acetate Amides such as N, N-dimethylformamide and N, N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide. Of these solvents, alcohols, aromatic hydrocarbons, and ether ketones are particularly preferably used. More preferable examples include toluene, xylene, 1-hexanol, 1,3-butanediol, 4-methoxy-4-methyl-2-pentanone, and the like.

  Among these, at least one kind of solvent is used, but two or more kinds of these solvents may be mixed and used. As the solvent to be mixed, ethers, alcohols, amides, sulfoxides, ether ketones amides, sulfoxides, ether ketones are suitable, among which ethers such as 1,2-dimethoxyethane, 1- Alcohols such as propanol are suitable. Particularly preferably, ethers are mixed. This is particularly from the standpoints of the crystal form stabilizing ability and dispersion stability of the phthalocyanine pigment when a coating solution is produced using oxytitanium phthalocyanine as a charge generation material.

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

  As shown in FIG. 2, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, a developing device 4, and a transfer device 5, and further, a cleaning device 6 and a fixing device as necessary. A device 7 is provided.

  When the electrophotographic photosensitive member of the present invention is not used, the exposure-charge repetitive characteristics under low temperature and low humidity are not stable, and image defects such as black spots and color spots frequently occur in the obtained image. As a result, it is not preferable because clear and stable image formation cannot be performed.

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

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 2, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but in addition, a corona charging device such as a corotron or a scorotron, a contact charging device such as a charging brush, and the like are often used.

  In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge having both of them (hereinafter referred to as a photosensitive cartridge as appropriate). It is desirable to use in such a form. In the present invention, as described above, when the charging unit is placed in contact with the electrophotographic photosensitive member, the effect is remarkably exhibited.

  For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light at the time of exposure is arbitrary, but for example, exposure may be performed with monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, monochromatic light with a wavelength shorter than 350 nm to 600 nm, or the like. . Among these, it is preferable to expose with monochromatic light having a short wavelength of 350 nm to 600 nm, and more preferably to expose with monochromatic light having a wavelength of 380 nm to 500 nm.

  The type of the developing device 4 is not particularly limited, and any device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method can be used. In FIG. 2, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which the toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. This replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.

  The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

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

  The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.

  The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in a variety of shapes ranging from a nearly spherical shape to a potato-like spherical shape. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a transfer material (paper, medium) P. Is. In the present invention, it is effective when the transfer device 5 is placed in contact with the photoreceptor via a transfer material.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner. However, when there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  The fixing device 7 includes an upper fixing member (pressure roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 2 shows an example in which a heating device 73 is provided inside the upper fixing member 71. As the upper and lower fixing members 71 and 72, a known heat fixing member such as a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll coated with a fluororesin, or a fixing sheet is used. be able to. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

  When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.

  The type of the fixing device is not particularly limited, and a fixing device of an arbitrary method such as heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like can be provided.

  In the image forming apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

  Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

  The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.

  When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

  After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

  In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

  In the present embodiment, the electrophotographic photosensitive member cartridge of the present invention has been described by exemplifying the photosensitive member cartridge including the electrophotographic photosensitive member 1 and the charging device 2. However, the electrophotographic photosensitive member cartridge of the present invention includes: The electrophotographic photosensitive member 1 may be provided with at least one of a charging device (charging unit) 2, an exposure device (exposure unit) 3, and a developing device (developing unit) 4. Specifically, for example, the electrophotographic photosensitive member cartridge of the present invention includes all of the electrophotographic photosensitive member 1, the charging device (charging unit) 2, the exposure device (exposure unit) 3, and the developing device (developing unit) 4. You may comprise as a cartridge.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto unless it exceeds the gist. In the examples, “parts” means “parts by weight” unless otherwise specified.

[Example 1]
Dissolve 10 parts of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) in 1,2-dimethoxyethane / 4-methoxy-4-methyl-2-pentanone = 9/1 mixed solution. To produce a polymer solution. Thereafter, 20 parts of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) was mixed with 1,2-dimethoxyethane / 4-methoxy-4-methyl-2-pentanone = 9/1. A liquid suspended in the solution was prepared and added to the previously prepared polymer solution to prepare a solution having a solid content concentration of 3.8 wt%. Ultra apex mill (UAM-015 type, hereinafter referred to as UAM) having a mill volume of about 0.15 L using zirconia beads having a diameter of about 30 μm (trade name: YTZ, manufactured by Nikkato Co., Ltd.) as a dispersion medium. Is used, and after a dispersion treatment for 20 minutes in a circulating state of a coolant at a rotor peripheral speed of 8 m / second and a liquid flow rate of 10 kg / hour, 5 ° C. to 12 ° C., a US treatment is performed for 150 minutes to generate charges. A layer coating solution SE1 was prepared.

  About the charge generation layer coating solution SE1, the rate of change in viscosity after preparation and after storage at room temperature for 120 days (the value obtained by dividing the difference between the viscosity after storage for 120 days and the viscosity during preparation by the viscosity at the time of preparation) and The particle size distribution and dispersion index of the phthalocyanine pigment at the time were measured.

  The viscosity was measured by a method according to JIS Z 8803 using an E-type viscometer (manufactured by Tokimec, product name: ED), and the particle size distribution was measured using the UPA. The dispersion index was defined as a value obtained by diluting the coating solution so that the absorbance at 775 nm was 1, and then dividing the absorbance at 775 nm by the absorbance at 1000 nm. The results are shown in Table 1.

[Example 2]
In Example 1, charge generation was carried out in the same manner as in Example 1 except that dispersion of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) with an ultra-apex mill was performed for 40 minutes. A layer coating solution SE2 was prepared. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
In Example 1, charge generation was carried out in the same manner as in Example 1 except that the dispersion of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) with an ultra apex mill was performed for 60 minutes. A layer coating solution SE3 was prepared. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
20 parts of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) and 375 parts of 1,2-dimethoxyethane may be mixed and abbreviated as a sand grind mill (hereinafter abbreviated as SGM). ) For 20 minutes (dispersion medium: Potters Barotini Co., Ltd., trade name: GB200M). Subsequently, this treatment solution was diluted with 120 parts of 1,2-dimethoxyethane, and 10 parts of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) were added to 1,2-dimethoxyethane. It was dripped in the binder liquid obtained by making it melt | dissolve in the liquid mixture of 135 parts and 76 parts of 4-methoxy-4-methyl-2-pentanone. Thereafter, a US treatment was performed for 150 minutes to prepare a charge generation layer coating solution SP1. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
Charge generation layer coating solution SP2 in the same manner as in Comparative Example 1 except that the dispersion of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) with a sand grind mill is 40 minutes. Was prepared. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
Charge generation layer coating solution SP3 in the same manner as in Comparative Example 1 except that the dispersion of D-type oxytitanium phthalocyanine (according to Production Example 1 described in Japanese Patent Application No. 2004-291274) with a sand grind mill was changed to 60 minutes. Was prepared. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
20 parts of A-type oxytitanium phthalocyanine (according to the example production method described in Japanese Patent Application No. 8-163133) in a 1,2-dimethoxyethane / 4-methoxy-4-methyl-2-pentanone = 9/1 mixed solution A suspension was prepared. Using a zirconia bead with a diameter of about 30 μm (product name: YTZ, manufactured by Nikkato Co., Ltd.) as a dispersion medium, an ultra apex mill (UAM-015 type) manufactured by Kotobuki Industries Co., Ltd. with a mill volume of about 0.15 L, and a rotor peripheral speed of 8 m / Second, a liquid flow rate of 10 kg / hour, and a dispersion treatment was performed for 1 hour in a state where a coolant at 5 to 12 ° C. was circulated. 10 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) was added to this dispersion, 1,2-dimethoxyethane / 4-methoxy-4-methyl-2-pentanone = 9 / After adding the polymer solution dissolved in one mixed solution (final solid content concentration 3.8%), it was subjected to US treatment for 150 minutes to prepare a charge generation layer coating solution SE4. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
In Example 4, a charge generation layer coating solution SE5 was prepared in the same manner as in Example 4 except that the dispersion by the ultra apex mill was changed to 2.5 hours. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
In Comparative Example 1, instead of D-type oxytitanium phthalocyanine, A-type oxytitanium phthalocyanine (according to the production method of Example described in Japanese Patent Application No. 8-163133) was used, and dispersion by sand grind mill (SGM) was 1 A charge generation layer coating solution SP4 was prepared in the same manner as in Example 1 except that the time was used. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
In Comparative Example 1, in place of D-type oxytitanium phthalocyanine, A-type oxytitanium phthalocyanine (according to the example production method described in Japanese Patent Application No. 8-163133) was used, and dispersion by sand grind mill (SGM) was performed. A coating solution SP5 was prepared in the same manner as in Example 1 except that the time was 2.5 hours. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
In Example 1, instead of D-type oxytitanium phthalocyanine, A-type oxytitanium phthalocyanine (according to the example production method described in Japanese Patent Application No. 8-163133) was used, and zirconia beads having a diameter of about 30 μm (Inc. Example 1 except that zirconia beads having a diameter of about 100 μm (manufactured by Nikkato Co., Ltd., trade name: YTZ) are used instead of Nikkato trade name: YTZ, and the dispersion by the ultra apex mill is set to 1 hour. Similarly, a charge generation layer coating solution SE6 was prepared. Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 6]
In Comparative Example 1, zirconia beads having a diameter of about 500 μm were used as a dispersion medium, using A-type oxytitanium phthalocyanine (according to an example production method described in Japanese Patent Application No. 8-163133) instead of D-type oxytitanium phthalocyanine. A charge generation layer coating solution SP6 was prepared in the same manner as in Comparative Example 1 except that Furthermore, the viscosity change rate, particle size distribution, and dispersion index were measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 7]
Mixing 1.5 parts of the charge generating material represented by the following formula and 30 parts of 1,2-dimethoxyethane, using zirconia beads having a diameter of about 200 μm (trade name: YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, Using an Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd. with a volume of about 0.15 L, a rotor circumferential speed of 8 m / sec, a liquid flow rate of 10 kg / hour, and a coolant at 5 ° C. to 12 ° C. circulated. The dispersion treatment was performed for 3 hours.

  Subsequently, 0.75 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) and 0.75 part of phenoxy resin (product of Union Carbide, PKHH) were added to 1,2-dimethoxyethane 28. The mixture is mixed with a binder solution dissolved in 5 parts, and finally, 13.5 parts of an arbitrary mixed liquid of 1,2-dimethoxyethane and 4-methoxy-4-methyl-2-pentanone is added to obtain a solid content (pigment + resin ) A charge generation layer coating solution SE7 having a concentration of 4.0% by weight was prepared.

  The dispersion index was obtained by diluting the coating solution so that the absorbance at 530 nm was 1, and then dividing the absorbance at 530 nm by the absorbance at 640 nm. Furthermore, the viscosity change rate and the particle size distribution were measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 7]
1.5 parts of the charge generating material used in Example 7 and 30 parts of 1,2-dimethoxyethane were mixed and dispersed for 8 hours in a sand grind mill (dispersion medium: GB200M). Subsequently, 0.75 part of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) and 0.75 part of phenoxy resin (product of Union Carbide, PKHH) were added to 1,2-dimethoxyethane 28. The mixture is mixed with a binder solution dissolved in 5 parts, and finally, 13.5 parts of an arbitrary mixed liquid of 1,2-dimethoxyethane and 4-methoxy-4-methyl-2-pentanone is added to obtain a solid content (pigment + resin ) A charge generation layer coating solution SP7 having a concentration of 4.0% by weight was prepared. The dispersion index was measured in the same manner as in Example 7. The viscosity change rate and the particle size distribution were measured in the same manner as in Example 1. The results are shown in Table 1.

[Evaluation 1]
The coating solution for charge generation layer prepared by the production method of the present invention has a smaller average particle size and a smaller particle size distribution width compared to those prepared by existing methods, so that the stability of the solution is improved. And a uniform charge generation layer can be formed, and the viscosity change is small and the stability is high even after long-term storage. Also, the time required to obtain the same dispersion is very short compared to a classic sand grind mill, etc., and it should be a coating solution prepared based on a highly efficient and highly productive method. I can say that.

[Example 8]
A rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were added to a Henschel mixer. 1 kg of a raw slurry obtained by mixing 50 parts of surface-treated titanium oxide obtained by mixing with 120 parts of methanol, and using a zirconia bead having a diameter of about 100 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0 Using a 15-liter Ultra Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd., a titanium oxide dispersion was prepared by dispersing for 1 hour in a liquid circulation state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 10 kg / hour. .

  The titanium oxide dispersion, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula Compound represented by (B)] / Hexamethylenediamine [Compound represented by the following formula (C)] / Decamethylene dicarboxylic acid [Compound represented by the following formula (D)] / Octadecamethylene dicarboxylic acid [Formula (E After the polyamide pellets are dissolved by stirring and mixing the pellets of the copolymerized polyamide having a composition molar ratio of 60% / 15% / 5% / 15% / 5%] , Ultrasonic dispersion using an ultrasonic transmitter with an output of 1200 W was performed for 1 hour, and a PTFE membrane filter (adva The weight ratio of the surface-treated titanium oxide / copolymerized polyamide is 3/1, and the weight ratio of the mixed solvent of methanol / 1-propanol / toluene is 7/1/2. A dispersion A for forming an undercoat layer having a solid content concentration of 18.0% by weight was obtained.

  The obtained coating solution A for forming the undercoat layer is dip-coated on an aluminum cutting tube having an outer diameter of 24 mm, a length of 236.5 mm, and a wall thickness of 0.75 mm so that the film thickness after drying becomes 2 μm. It was applied and dried to form an undercoat layer.

  The charge generation layer dispersion liquid SE3 was filtered through a PTFE membrane filter having a pore diameter of 5 μm (Advantech Mytecs LC) to prepare a charge generation layer coating liquid. This charge generation layer coating solution was applied and dried by dip coating on the undercoat layer such that the film thickness after drying was 0.4 μm to form a charge generation layer.

  Next, on this charge generation layer, 56 parts of the hydrazone compound shown below,

14 parts of a hydrazone compound shown below,

100 parts of a polycarbonate resin having the following repeating structure;

A charge transport layer coating solution in which 0.05 part by weight of silicone oil was dissolved in 640 parts by weight of a tetrahydrofuran / toluene (8/2) mixed solvent was applied so that the film thickness after drying was 17 μm. And air dried for 25 minutes. Furthermore, it was dried at 125 ° C. for 20 minutes to provide a charge transport layer to produce an electrophotographic photoreceptor. This electrophotographic photosensitive member is referred to as a photosensitive member P1.

[Evaluation 2]
The dielectric breakdown strength of this photoreceptor P1 was measured as follows. That is, the photoconductor is fixed in an environment of a temperature of 25 ° C. and a relative humidity of 50%, a volume resistivity is about 2 MΩ · cm, a charging roller that is shorter by about 2 cm at both ends than the drum length is pressed, and a DC voltage of −3 kV is applied. As a result of measuring the time until dielectric breakdown, it was 22 minutes.

In addition, an electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (edited by the Electrophotographic Society, “Basics and Applications of Secondary Electrophotographic Technology”, Corona, 1996, pages 404 to 405). ) (Mitsubishi Chemical Co., Ltd.) and charged so that the surface potential is −700 V, then irradiated with 780 nm laser light at an intensity of 5.0 μJ / cm ² , the surface after 100 msec after exposure The potential (VL) was measured under a temperature of 25 ° C. and a relative humidity of 50% (hereinafter sometimes referred to as NN environment), and at a temperature of 5 ° C. and a relative humidity of 10% (hereinafter sometimes referred to as LL environment). The results are shown in Table 2.

  The electrophotographic photosensitive member of the present invention has a uniform layer without aggregation and the like, has a small potential fluctuation due to environmental differences, and is excellent in dielectric breakdown resistance.

[Example 9]
As the coating solution for forming the undercoat layer, the coating solution A for forming the undercoat layer described in the above examples was used by dip coating on an aluminum cutting tube having an outer diameter of 30 mm, a length of 285 mm, and a wall thickness of 0.8 mm. It applied so that the film thickness after drying might be set to 2.4 micrometers, and it was made to dry and the undercoat layer was formed.

  The charge generation layer coating solution SE3 was applied on the undercoat layer by dip coating so that the film thickness after drying was 0.4 μm, and dried to form a charge generation layer.

  Next, on the charge generation layer, a composition (A) produced according to the description in Example 1 of JP-A-2002-080432, which mainly comprises a structure shown in the following composition (A) as a charge transport material. 60 parts,

100 parts of polycarbonate resin having the following repeating structure,

And a coating solution prepared by dissolving 0.05 part by weight of silicone oil in 640 parts by weight of a tetrahydrofuran / toluene (8/2) mixed solvent is applied so that the film thickness after drying is 10 μm, and dried to charge transport. A layer was provided to produce an electrophotographic photoreceptor.

  The produced photoreceptor was mounted on a cartridge of a color printer (product name: InterColor LP-1500C) manufactured by Seiko Epson Corporation, and a full color image was formed. As a result, a good image could be obtained. The number of minute color points observed in the obtained 1.6 cm square of the image was only 8.

  The electrophotographic photosensitive member of the present invention has very excellent performance with excellent characteristics of the photosensitive member, resistance to dielectric breakdown, and few image defects such as color points.

[Example 10]
The undercoat layer forming coating solution A was applied on an aluminum cutting tube having an outer diameter of 24 mm, a length of 236.5 mm, and a thickness of 0.75 mm by dip coating so that the film thickness after drying was 2 μm. An undercoat layer was formed by drying. The photosensitive layer forming coating solution SE7 was dip coated on the undercoat layer so that the film thickness after drying was 0.6 μm, and then dried to form a charge generation layer.

  Next, on this charge generation layer, 67 parts of a triphenylamine compound shown below,

100 parts of polycarbonate resin having the following repeating structure,

0.5 part of a compound having the structure

And a coating solution for charge transport layer in which 0.02 part by weight of silicone oil was dissolved in 640 parts by weight of a tetrahydrofuran / toluene (8/2) mixed solvent was applied so that the film thickness after drying was 25 μm. And then dried at 125 ° C. for 20 minutes to provide a charge transport layer to prepare an electrophotographic photosensitive member.

[Evaluation 3]
An electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (Electrophotographic Society of Japan, “Basics and Applications of Sequential Electrophotographic Technology”, Corona, 1996, 404) (Pages 405 to 405) (Mitsubishi Chemical Co., Ltd.), and the electrical characteristics were evaluated according to the cycle of charging, exposure, potential measurement, and static elimination according to the following procedures.

In the dark, the initial surface potential of the photoconductor was measured when the photoconductor was charged by discharging at a grid voltage of -800 V of a scorotron charger. Next, the irradiation light (μJ / cm ² ) when the surface potential is −350 V is measured by irradiating the light of the halogen lamp with 450 nm monochromatic light using an interference filter, and this value is the sensitivity E _{1. As} a result, the initial charging potential was −710 V and the sensitivity E _1/2 was 3.3 μJ / cm ² .

[Example 11]
The undercoat layer forming coating solution A used in Example 8 was coated on a polyethylene terephthalate sheet having aluminum deposited on the surface with a wire bar so that the film thickness after drying was 1.2 μm, and dried to form an undercoat layer. Was provided. Next, 5 parts by weight of D-type oxytitanium phthalocyanine used in Example 1 (Production Example 1 described in Japanese Patent Application No. 2004-291274), together with 70 parts by weight of toluene, zirconia beads having a diameter of about 30 μm (manufactured by Nikkato Corporation) (Product name: YTZ) is used as a dispersion medium, an ultra apex mill (UAM) manufactured by Kotobuki Industries Co., Ltd. with a mill volume of about 0.15 L, a rotor peripheral speed of 8 m / second, a liquid flow rate of 10 kg / hour, and 5 ° C. to 12 ° C. A dispersion treatment was performed for 20 minutes in a state where the cooling liquid was circulated, and then a US treatment was performed for 150 minutes to obtain a dispersion SE8. Further, a dispersion SE9 was prepared in the same manner as SE8, except that 8 parts by weight of the electron transport material represented by the following structural formula (6) was used together with 112 parts by weight of toluene without using the above-mentioned D-type oxytitanium phthalocyanine. Got.

  On the other hand, 60 parts by weight of the hole transport material represented by the following structural formula (7) and 100 parts by weight of the polycarbonate resin used in Example 10 were dissolved in 420 parts by weight of toluene, and 0.05 parts by weight of silicone oil was used as a leveling agent. Was added, and the above two types (SE8, SE9) of dispersion were mixed with a homogenizer so as to be uniform. The coating solution thus prepared was applied on the undercoat layer so that the film thickness after drying was 25 μm to obtain a positively charged single layer type sheet-like electrophotographic photoreceptor EX. At this time, the solubility of the resin in the solvent was good, and no symptoms such as gelation were observed even after one month had passed since the coating solution was prepared.

[Evaluation 4]
Using an electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard ("Continuing Electrophotographic Technology Fundamentals and Applications", edited by the Electrophotographic Society, Corona, pages 404-405), the above-mentioned photoreceptor EX has a diameter. Affixed to an aluminum drum of 80 mm to form a cylindrical shape, and the aluminum drum and the aluminum substrate of the photoreceptor EX are electrically connected. Then, the drum is rotated at a constant rotational speed of 60 rpm to charge, expose, measure potential, An electrical property evaluation test was carried out by a charge removal cycle. At that time, the surface potential after exposure (when the initial surface potential of the photoreceptor is charged to +700 V and the light of the halogen lamp is changed to 780 nm monochromatic light with an interference filter at 1.5 μJ / cm ² is exposed. Hereinafter, it may be referred to as “VL +”). In the VL measurement, the time required from the exposure to the potential measurement was 100 ms. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%. The results are shown in Table 3.

[Comparative Example 8]
Instead of UAM used in Example 11, dispersion treatment was performed with a sand grind mill (SGM) for 20 minutes (dispersion medium: manufactured by Potters Ballotini Co., Ltd., trade name: GB200M), and dispersion containing D-type oxytitanium phthalocyanine A positively charged single layer type electrophotographic photoreceptor PX was obtained in the same manner as in Example 11 except that the solution and a dispersion containing the hole transport material represented by the structural formula (7) were obtained. At this time, although the solubility of the resin in the solvent was good, gelation of the solution was observed when one month passed after the coating solution was prepared. Electrical characteristics were measured in the same manner as in Example 11. The results are shown in Table 3.

  The coating solution for forming a photosensitive layer of the present invention has high storage stability, and can produce an electrophotographic photosensitive member having a charge generation layer formed by coating the coating solution with high quality and high efficiency, Since the electrophotographic photosensitive member is excellent in durability stability and hardly causes image defects and the like, an image forming apparatus using the photosensitive member can form a high-quality image. In addition, according to the method for producing a coating solution for forming a photosensitive layer, the coating solution can be produced efficiently, and a coating solution with higher storage stability can be obtained. Further, a higher quality electrophotographic photosensitive member can be obtained. Can be obtained. Therefore, it can be suitably used in various fields in which the electrophotographic photosensitive member is used, for example, in the fields of copying machines, printers, printing machines and the like.

It is a longitudinal cross-sectional view of the wet stirring ball mill in connection with this invention. 1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus including an electrophotographic photosensitive member of the present invention.

Explanation of symbols

1 Photoconductor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (pressure roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Transfer material (paper, medium)
14 Separator 15 Shaft 16 Jacket 17 Stator 19 Discharge path 21 Rotor 24 Pulley 25 Rotary joint 26 Raw material slurry supply port 27 Screen support 28 Screen 29 Product slurry take-out port 31 Disc 32 Blade 35 Valve body

Claims (16)

  In a method for producing a coating solution for forming a photosensitive layer of an electrophotographic photoreceptor containing a charge generating material and a binder resin, an average particle size of 1 is used as a dispersion medium for dispersing the charge generating material in the coating solution for forming a photosensitive layer. A method for producing a coating solution for forming a photosensitive layer, characterized by using a dispersion medium in a range of 0.0 μm to 350 μm.   The method for producing a coating solution for forming a photosensitive layer according to claim 1, wherein the dispersion medium is zirconia beads.   The method for producing a coating solution for forming a photosensitive layer according to claim 1 or 2, wherein the dispersion of the charge generation material using the dispersion medium is performed using a ball mill. The ball mill includes a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, the dispersion medium filled in the stator, and the slurry supply The slurry containing the charge generation material and the binder resin supplied from the mouth is stirred and mixed, and is connected to the slurry discharge port, and is separated into a dispersion medium and a slurry by the action of centrifugal force. A wet stirring ball mill having a separator for discharging slurry from the slurry discharge port,
The method for producing a coating solution for forming a photosensitive layer according to any one of claims 1 to 3, wherein an axis of a shaft for rotationally driving the separator has a hollow discharge passage communicating with the slurry discharge port. The ball mill includes a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, the dispersion medium filled in the stator, and the slurry supply The slurry containing the charge generation material and the binder resin supplied from the mouth is stirred and mixed, and is connected to the slurry discharge port, and is separated into a dispersion medium and a slurry by the action of centrifugal force. A wet stirring ball mill having a separator for discharging slurry from the slurry discharge port,
The separator includes two disks having a fitting groove of a blade on the inner surface facing each other, a blade fitted in the fitting groove and interposed between the disks, and the disk having the blade interposed therebetween. The method for producing a coating solution for forming a photosensitive layer according to any one of claims 1 to 3, further comprising supporting means for sandwiching from both sides.   A photosensitive layer forming coating solution produced by the method for producing a photosensitive layer forming coating solution according to claim 1.   In a coating solution for forming a photosensitive layer of an electrophotographic photoreceptor containing a charge generation material and a binder resin, the charge generation material is a phthalocyanine pigment, and is measured by a dynamic light scattering method of the phthalocyanine pigment in the coating solution. A coating solution for forming a photosensitive layer, wherein the cumulative 50% particle diameter (D50) is 0.13 μm or less.   8. The coating for forming a photosensitive layer according to claim 7, wherein the phthalocyanine pigment has a volume average particle size of 0.05 μm or less and a cumulative 90% particle size (D90) of 0.25 μm or less. liquid.   An electrophotographic photoreceptor comprising a photosensitive layer formed using the coating solution for forming a photosensitive layer according to claim 6.   10. The photosensitive layer is a single-layer type photosensitive layer formed using a coating solution in which a charge transport material is further added to the photosensitive layer forming coating solution containing a charge generating material. The electrophotographic photoreceptor described in 1.   A laminate type in which the photosensitive layer is formed by laminating a charge generation layer formed of the coating solution for forming a photosensitive layer containing a charge generation material and a charge transport layer formed of a coating solution containing a charge transport material. The electrophotographic photosensitive member according to claim 9, wherein the electrophotographic photosensitive member is a photosensitive layer.   12. An electrophotographic photosensitive member according to claim 9, a charging means for charging the electrophotographic photosensitive member, and an image for exposing the charged electrophotographic photosensitive member to image exposure to form an electrostatic latent image. An image forming apparatus comprising: an exposure unit; a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target.   The charging unit is disposed in contact with the electrophotographic photosensitive member at least when charging the electrophotographic photosensitive member or developing a latent image formed on the electrophotographic photosensitive member. 12. The image forming apparatus according to 12.   The image forming apparatus according to claim 12 or 13, wherein the light used for the image exposure means has a wavelength within a range of 350 nm to 600 nm.   12. The electrophotographic photosensitive member according to claim 9, charging means for charging the electrophotographic photosensitive member, and image exposure for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image. Means for developing the electrostatic latent image formed on the electrophotographic photosensitive member with toner, transfer means for transferring the toner to the transfer target, and collecting the toner adhering to the electrophotographic photosensitive member An electrophotographic photosensitive member cartridge comprising: at least one of cleaning means for cleaning.   The charging unit is disposed in contact with the electrophotographic photosensitive member at least when charging the electrophotographic photosensitive member or developing a latent image formed on the electrophotographic photosensitive member. 15. The electrophotographic cartridge according to 15.

Images