JP2002341564A - Method for producing coating liquid for electrophotographic sensitive body, and electrophotographic sensitive body, electrophotographic device and process cartridge for electrophotographic device using the same coating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing coating liquid for an electrophotographic sensitive body having no defect of a coating film, excellent in coating property and showing good stability, and also to provide an electrophotographic sensitive body having no defect of the coating film, excellent in the coating property and showing the good stability by using the coating liquid for the electrophotographic sensitive body. SOLUTION: In this method for producing the coating liquid for the electrophotographic sensitive body constituted by at least dispersing azo pigments in a solvent, a dispersion medium for dispersing the pigment particles has density (D: g/cm<2> ) and a diameter (R: mm) expressed by a following expression (A). D×R>=65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a coating solution for an electrophotographic photosensitive member, an electrophotographic photosensitive member using the same, an electrophotographic apparatus using the same, and a process cartridge for the electrophotographic device. More specifically, the present invention particularly relates to a method for producing an electrophotographic photoreceptor coating solution having excellent coating properties and excellent storage stability, and is prepared using such an electrophotographic photoreceptor coating solution. The present invention relates to an electrophotographic photosensitive member that provides a high-quality image without image defects, an electrophotographic device using the electrophotographic photosensitive member, and a process cartridge for the electrophotographic device.

[0002]

2. Description of the Related Art Conventionally, inorganic materials such as Se, CdS, and ZnO have been used as a photoconductive material for an electrophotographic photoreceptor, but they have problems such as photosensitivity, thermal stability, and toxicity. In recent years, electrophotographic photoconductors using organic photoconductive materials have been actively developed, and electrophotographic photoconductors having a photosensitive layer containing a charge generation material and a charge transport material have been developed.
It has already been put to practical use.

Generally, a photosensitive layer of an electrophotographic photosensitive member using an organic photoconductive material comprises at least a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. The generating layer is prepared by dispersing at least the charge generating substance in a suitable solvent using a ball mill, an attritor, a sand mill, ultrasonic waves, etc. to prepare a coating liquid, applying the coating liquid on a conductive support or an intermediate layer, and drying. It is formed by this. When a phthalocyanine pigment is used as the charge generating substance, it is necessary to disperse the phthalocyanine pigment without destroying the crystal form since the characteristics of the phthalocyanine pigment itself largely depend on the crystal form. For this reason, in order to disperse the phthalocyanine pigment, a bead mill, a sand mill, or the like, which has a relatively small dispersion share but can reduce the dispersion particle size, is often used.

On the other hand, when an azo pigment is used as a charge generating substance, since the azo pigment itself has a high cohesiveness and a high hardness as a solid substance, dry pulverization is introduced in advance or the dispersion time is lengthened. In many cases, a coating liquid is created by doing so. However, any of these means increases the number of steps and man-hours, and takes time and effort, which is not preferable in the production process of the coating liquid.

[0005] In addition, azo pigments are considered to exhibit a function of generating electric charge by taking a state in which a kind of single molecule is aggregated, so that the storage stability after preparing a coating liquid is small, and The charge generation characteristics change, or the liquid properties of the coating liquid change, and aggregates are formed, or the viscosity increases, thereby deteriorating the coating quality of the coated electrophotographic photoreceptor. In the worst case, it had to be discarded.

Various proposals have been made for dispersing methods to solve the above problems, but at present it has not been possible to obtain satisfactory coating properties required for the coating solution for the photoreceptor. . For example, Japanese Patent Application Laid-Open No. 6-043672
In the publication, the average particle size is 0.4 to
The use of 0.8 mm spherical media is disclosed. Further, Japanese Patent Application Laid-Open No. HEI 8-123,045 discloses a technique of dispersing in a crystalline glass medium to prevent abrasion powder of the medium from being mixed.

As a dispersion method, for example, a method of first performing dry pulverization, sending a liquid to the pulverization container, and performing wet pulverization there (JP-A-1-176433, JP-A-1-1717)
6434), a method in which an organic pigment is dry-pulverized using an alumina-based medium in advance and then dispersed (Japanese Patent Laid-Open No.
JP-A-223272), a method of dispersing an organic pigment in a solvent together with a spherical pulverizing medium having an average particle size of 0.4 to 0.8 mm (JP-A-6-433762), (JP-A-7-152188), a method in which coarse crystalline pigments are first subjected to dry milling and then wet-milled in a stirring ball mill to obtain coarse and fine particles. 8-4
No. 1368).

[0008] However, any of the methods disclosed in each of the publications can provide a good coating liquid as an initial dispersion state, but has poor stability over time and increases the viscosity of the coating liquid over time. Problems such as generation of aggregates on the coated photoreceptor occur.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a coating solution for an electrophotographic photoreceptor which has no coating film defects, has excellent coating properties, and exhibits good stability. The subject. Another object of the present invention is to provide an electrophotographic photoreceptor which provides a high-quality image free from image defects and which is prepared using the electrophotographic photoreceptor coating solution.
Further, the present invention provides an electrophotographic apparatus and a process cartridge for an electrophotographic apparatus using an electrophotographic photosensitive member that provides a high-quality image without image defects, prepared using the electrophotographic photosensitive member coating solution of the present invention. Doing so is another task.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the use of a dispersion medium having a specific density and a specific diameter as a dispersion medium for dispersing pigment molecules has resulted in the above-mentioned problems. Can be solved, and have completed the present invention. That is, according to the present invention, the above problem can be solved by employing the following technical means. (1) In a method for producing a coating liquid for an electrophotographic photoreceptor comprising at least an azo pigment dispersed in a solvent, a dispersion medium for dispersing the pigment particles has a density represented by the following formula (A): D: g / cm ² ) and a diameter (R: mm). D × R ≧ 65 (A) (2) The method for producing a coating liquid for an electrophotographic photosensitive member according to the above (1), wherein the dispersion medium is a zirconia ball. (3) The azo pigment is represented by the following general formula (I): Cp ₁ -N = N-AN = N-Cp ₂ (I) wherein A is a carbon atom and is an azo group. represents a divalent residue bonded to the nitrogen atom;. Cp ₁ and Cp ₂ is the which is a asymmetric disazo pigment represented by mutually indicating the different coupler residues of structure) (1 wherein (4) The method for producing a coating liquid for an electrophotographic photosensitive member according to (3), wherein the asymmetric azo pigment represented by the general formula (I) is a compound represented by the following general formula (II). The method for producing a coating liquid for an electrophotographic photosensitive member according to the above).

Embedded image (In the formula, Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) (5) In an electrophotographic photoreceptor obtained by sequentially laminating at least a charge generation layer or a charge transport layer on a conductive support. ,
An electrophotographic photosensitive member, wherein the charge generation layer is formed using the electrophotographic photosensitive member coating liquid according to any one of the above (1) to (4). (6) at least a charging unit, an image exposing unit, a developing unit,
An electrophotographic apparatus comprising a transfer unit, a charge removing unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to the above (5). (7) An electrophotographic process cartridge including at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to (5). Process cartridge.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The method for producing an electrophotographic photosensitive member according to the present invention is a method for producing a coating liquid for an electrophotographic photosensitive member comprising at least an azo pigment dispersed in a solvent. And diameter are represented by the following formula (A): D × R ≧ 65 (A) (where D means density (g / cm ² ) and R means diameter (mm)). Using a dispersion media that satisfies

In the method of manufacturing an electrophotographic photosensitive member according to the present invention, the dispersion medium is preferably a zirconia ball. Further, according to the present invention, the azo pigment includes the following general formula (I): Cp ₁ −N = N−A−N = N−Cp ₂ (I) A divalent residue bonded to the nitrogen atom of the azo group by a carbon atom; Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) It is possible to use an asymmetric disazo pigment represented by the following formula: preferable.

Further, according to the present invention, the above-mentioned general formula (I)
The asymmetric azo pigment represented by the following general formula (II):

Embedded image (Wherein, Cp ₁ and Cp ₂ have the same meanings as described above).

Further, the electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, wherein the charge generation layer comprises: It is formed using the electrophotographic photoreceptor coating solution of the present invention. Furthermore, the process cartridge for an electrophotographic apparatus according to the present invention includes at least the electrophotographic photosensitive member according to the present invention.

Hereinafter, the present invention will be described with reference to the configuration of an electrophotographic photosensitive member. FIG. 1 is a cross-sectional view showing a configuration example of the electrophotographic photoreceptor of the present invention, in which a photosensitive layer 15 formed by applying a coating liquid containing at least an azo pigment on a conductive support 11 is laminated. Has taken. FIG. 2 is a cross-sectional view showing another example of the configuration of the electrophotographic photoreceptor of the present invention, and a charge generation layer formed by applying a charge generation layer coating solution containing at least an azo pigment on a conductive support 11. It has a configuration in which a layer 17 and a charge transport layer 19 are stacked. FIG. 3 is a cross-sectional view showing another configuration example of the present invention, in which an intermediate layer 13 is provided between a conductive support 11 and a charge generation layer 17. FIG.
FIG. 3 is a cross-sectional view showing still another configuration example of the present invention, in which a protective layer 21 is provided on a charge transport layer 19.

In FIGS. 1 to 4, the conductive support 11 is made of a material having a volume resistivity of 10 ¹⁰ Ω · cm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum. Materials such as metal or tin oxide, metal oxides such as indium oxide, coated by vapor deposition or sputtering on a film or cylindrical plastic or paper, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. Extruded, drawn out, etc., and then cut,
A tube or the like that has been subjected to surface treatment such as superfinishing or polishing can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support 11. In addition, as the conductive support 11 of the present invention, a support obtained by dispersing a conductive powder on a suitable binder resin and coating the support on the support can be used. Examples of the conductive powder include carbon-based substances such as carbon black and acetylene black; metal powders such as aluminum, nickel, iron, nichrome, copper, zinc, and silver; conductive titanium oxide, conductive tin oxide, and ITO. And the like. The binder resins used simultaneously include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal,
Polyvinyl toluene, poly-N-vinyl carbazole,
Thermoplastic, thermosetting or photo-curable resins such as acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, 2-butanone, toluene, or the like, and applying the dispersion. Further, as the conductive support 11 of the present invention, polyvinyl chloride, polypropylene, polyester,
A material in which a conductive layer is provided by a heat-shrinkable tube containing the above-described conductive powder in a material such as polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon (registered trademark) can also be used favorably.

As the charge generating substance, azo pigments such as monoazo pigments, bisazo pigments, asymmetric disazo pigments, trisazo pigments and tetraazo pigments can be used as shown in the present invention. Specifically, an azo pigment having a carbazole skeleton (described in JP-A-53-95033), an azo pigment having a triphenylamine skeleton (described in JP-A-53-13247), and a stilbene skeleton Azo pigments (JP-A-53-138229)
Azo pigment having a dibenzothiophene skeleton (described in JP-A-54-21728), and an azo pigment having a fluorenone skeleton (described in JP-A-54-22834).
Azo pigments having an oxadiazole skeleton (described in JP-A-54-12742) and azo pigments having a bisstilbene skeleton (described in JP-A-54-17733).
Azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-2129),
And azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-17734).

Among these azo pigments, it is preferable to use an asymmetric disazo pigment having an extremely high sensitivity represented by the above formula (I). These asymmetric disazo pigments
After reacting the corresponding diazonium salt compound and the coupler corresponding to Cp ₁ or Cp ₂ sequentially in two steps, or isolating the diazonium salt compound obtained by the first coupling reaction with Cp ₁ or Cp ₂ , Further, it can be obtained by reacting the remaining coupler.

Examples of A of these asymmetric disazo pigments are shown below, but it goes without saying that the present invention is not limited to the following examples.

[0020]

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[0021]

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The coupler Cp of these asymmetric disazo pigments
Examples of ₁ and Cp ₂ are illustrated below, but it goes without saying that the present invention is not limited to the following examples.

[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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In the general formula (II), preferred examples of the couplers Cp ₁ and Cp ₂ include the following general formulas (IV) to (I)
X).

[0031]

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In the general formulas (IV) and (V), X is a naphthalene ring, anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, dibenzothiophene ring which may be substituted by condensing with a benzene ring. Represents a residue necessary for forming a hydrocarbon ring or a heterocyclic group. In the formula (VIII), Y represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent heterocyclic group containing a nitrogen atom in the ring. In the general formulas (IV) and (V), R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group,
It represents an aralkyl group or a heterocyclic group, and R ₁ and R ₂ or R ₃ and R ₄ may combine a nitrogen atom to form a cyclic amino group containing a nitrogen atom in the ring. In the general formula (VI), R ₅ represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group or a heterocyclic group.
In the general formulas (VII) and (VIII), R ₆ and R ₇ each represent an alkyl group which may have a substituent, an aryl group,
Represents an aralkyl group or a heterocyclic group. In the general formulas (VI) and (VII), Ar ₁ and Ar ₂ each represent an aryl group or a heterocyclic group which may have a substituent. In the general formula (IV), p represents 0 or 1.

Examples of the alkyl group in the above expression include, for example,
Groups such as methyl, ethyl and propyl, aralkyl groups such as benzyl and phenethyl, aryl groups such as phenyl, naphthyl and anthryl, and heterocyclic groups such as pyridyl, thienyl, thiazolyl, carbazolyl, benzimidazolyl and benzothiazolyl Examples of the cyclic amino group containing a nitrogen atom in the ring include pyrrole, pyrroline, pyrrolidine, pyrrolidone, indole, indolyl, carbazole, imidazole, pyrazole, pyrazoline, oxazine, phenoxazine and the like. Examples of the substituent include an alkyl group such as methyl, ethyl, propyl and butyl, an alkoxy group such as methoxy, ethoxy and propoxy, a fluorine atom,
Examples include a halogen atom such as a chlorine atom and a bromine atom, a dialkylamino group such as dimethylamino and diethylamino, a halomethyl group such as a phenylcarbamoyl group, a nitro group, a cyano group, and trifluoromethyl.

Among these asymmetric disazo pigments, A
The compound represented by the above general formula (II) having a fluorenone central skeleton represented by -20 is particularly preferred from the viewpoint of sensitivity and potential stability. Specific examples of the asymmetric disazo pigment represented by the general formula (II) are shown below, but the present invention is not limited thereto.

[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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Since these asymmetric azo pigments are asymmetric, it is considered that the distribution of electric charges is biased as compared with the symmetric azo pigment, and the interaction between molecules is stronger. Therefore, it is considered that the storage stability in the case of a coating liquid is poor. However, if the dispersion is performed by the method of the present invention, the effect is remarkable and a more preferable combination is obtained.

The charge generation layer 17 was obtained by dispersing at least an azo pigment in an appropriate solvent by using a conventional pulverizing means such as a ball mill, an attritor, a sand mill, and ultrasonic waves to prepare a coating liquid. It can be formed by applying a coating liquid on the conductive support 11 or the intermediate layer 13 and drying. In the present invention, it is preferable that the dispersion medium for dispersing the azo pigment has a density and a diameter represented by the following formula (A). D × R ≧ 65 (A) D: Density (g / cm ² ) R: Diameter (mm)

By preparing a coating liquid by the method according to the present invention, it becomes possible to disperse the azo pigment in a satisfactory manner. The problem of occurrence does not occur.

The material of the dispersion medium usable in the present invention is soda glass (SiO ₂ 70 to 73%, Na ₂ O
13-15%), low alkali glass (SiO ₂ 42)
_{~52%, Al 2 O 3 13~23} %, CaO 10~2
5%, CaO + MgO 18-32%), yttria-containing zirconia (ZrO ₂ 93-95%, Y ₂ O ₃ 4-6)
%), Alumina _{(Al 2 O 3 91~93%)} , titania _{(TiO 2 77.7%, Al 2} O 3 17.4%, Si
O ₂ 4.6%), zircon (ZrO ₂ 68.5%, S
iO ₂ 31%). Among these dispersing media materials, glass is weak in strength, easily broken, easily remains as a foreign substance in the coating liquid, and the alumina itself also wears out during the dispersion of the alumina, and also as an impurity in the coating liquid. There is a disadvantage that it tends to remain. Therefore, in the present invention, it is preferable to use zirconia balls as the material of the dispersion medium.

Although the reason why the dispersion method of the present invention is preferred is not clear, as described above, azo pigments generally require mechanical strain for dispersion, and pigment solids are initially dispersed. Pulverization occurs, and then aggregates are formed as molecules having good electrostatic properties while reducing the particle size to some extent. On the other hand, in a general dispersion method, the bonding force of the molecular aggregate is weak, so that the molecular aggregate is loosened with time, causing an increase in viscosity, forming a different aggregate, and causing a coating film defect on the photoconductor. Become. Therefore, by using the dispersion method of the present invention, an appropriate mechanical strain acts on the azo pigment, and it is possible to form a strong molecular aggregate during dispersion. Thus, it is considered that a coating solution having excellent stability over time was able to be prepared without the molecular aggregates being loosened over time.

Solvents used for preparing the coating liquid for the charge generation layer include methanol, ethanol, n-butanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, and acetic acid. Methyl, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene,
Xylene, ligroin and the like can be mentioned. As a method of applying the coating solution, a method such as a dip coating method, a spray coat, a bead coat, a nozzle coat, a spinner coat, and a ring coat can be used.

The binder resin used for the charge generation layer 17 is polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl formal, polyvinyl ketone, polystyrene, poly-vinyl carbazole, polyacrylamide, polyvinyl Butyral, polyvinyl benzal,
Examples include polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, and the like. The amount of the binder resin is suitably from 10 to 500 parts by weight, preferably from 25 to 300 parts by weight, per 100 parts by weight of the charge generating substance. The thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.1 to 2 μm.

The charge transporting layer 19 can be formed by dissolving or dispersing a charge transporting substance and a binder resin in a suitable solvent, applying the solution on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent and the like can be added. The charge transport materials include an electron transport material and a hole transport material. Examples of the electron transport material include chloranil,
Bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,
4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4
-One, 1,3,7-trinitrodibenzothiophene-
Electron accepting substances such as 5,5-dioxide and benzoquinone derivatives are exemplified.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives,
Monoarylamine derivatives, diarylamine derivatives,
Triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives,
Known materials such as a butadiene derivative, a pyrene derivative, a bisstilbene derivative, an enamine derivative, and other polymerized hole transport substances are exemplified.

Examples of the binder resin used for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride-acetic acid. Vinyl copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, Epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, JP-A-5-158250 and JP-A-6-5
Thermoplastic or thermosetting resins such as various polycarbonate copolymers described in JP-A-1544.

The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 15 parts by weight, per 100 parts by weight of the binder resin.
0 parts by weight is suitable. The charge transport layer has a thickness of 5 to 5.
Preferably, the thickness is about 50 μm.

Solvents used in the charge transport layer include tetrahydrofuran, dioxane, dioxolan, toluene, xylene, monochlorobenzene, dichloroethane,
Dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

Further, a leveling agent, an antioxidant and the like may be added to the charge transport layer 19. As the leveling agent, silicone oils such as dimethylsilicone oil and methylphenylsilicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain can be used, and the amount used is based on 100 parts by weight of the binder resin. 0 to 1 part by weight is suitable. As the antioxidant, an antioxidant such as a hindered phenol compound, a sulfur compound, a phosphorus compound, a hindered amine compound, a pyridine derivative, a piperidine derivative, and a morpholine derivative can be used.

In the electrophotographic photosensitive member of the present invention, an intermediate layer 13 can be provided between the conductive support 11 and the photosensitive layer 15. The intermediate layer 13 generally contains a resin as a main component. However, considering that these resins are coated with a photosensitive layer with a solvent, the resin should be a resin having high solvent resistance to a general organic solvent. Is desirable. As such a resin,
Water-soluble resins such as polyvinyl alcohol, casein and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, phenolic resin, alkyd-melamine resin, epoxy resin, etc., three-dimensional network structure And the like. Further, the intermediate layer 13 may be added with a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, etc. for preventing moiré and reducing residual potential. Good.

Further, as the intermediate layer 13 of the present invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, a titanyl chelate compound, a zirconium chelate compound, a titanyl alkoxide compound, and an organic titanyl compound can be used. In addition, the intermediate layer 13 of the present invention is provided with Al ₂ O ₃ by anodic oxidation, or an organic material such as polyparaxylylene, SiO ₂ , Sn, or the like.
Those provided with an inorganic substance such as O ₂ , TiO ₂ , ITO, CeO ₂ by a vacuum thin film forming method can also be used favorably. These intermediate layers 13 are made of a suitable solvent, dispersion,
It can be formed using a coating method. The thickness of the intermediate layer 13 is suitably from 0 to 10 μm.

The protective layer 21 is provided for the purpose of improving the durability of the photoconductor. Materials used for the protective layer 21 include:
ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone Resins such as polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, etc. No.

For the purpose of improving abrasion resistance, a fluorine resin such as polytetrafluoroethylene, a silicone resin, or an inorganic material such as titanium oxide, tin oxide or potassium titanate is added to the protective layer 21. Can be. AC and aS formed by a vacuum thin film forming method
A known material such as iC can be used as the protective layer 21. As a method for forming the protective layer 21, a normal coating method can be used. The thickness of the protective layer 21 is 0.1
10 to 10 μm is appropriate.

In the present invention, the photosensitive layer 15 and the protective layer 21
It is also possible to provide another intermediate layer (not shown) between them. The other intermediate layer generally uses a resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon resin, water-soluble butyral resin, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the other intermediate layer, a normal coating method can be used as described above. The thickness is 0.05 to 2
μm is appropriate.

Next, the electrophotographic apparatus and the process cartridge for the electrophotographic apparatus used in the present invention will be described. FIG. 5 is a schematic diagram for explaining the electrophotographic apparatus according to the present invention, and the present invention is not limited to the embodiment shown in the figure at all, and the following modified examples also belong to the category of the present invention. Things. In FIG. 5, an electrophotographic photoreceptor 1 is provided with a photosensitive layer formed on a conductive support using a dispersion prepared by the above-described method. The electrophotographic photoreceptor 1 has a drum shape, but may have a sheet shape or an endless belt shape. As the charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. Can be The transfer means
Generally, the above chargers can be used.

The light sources such as the image exposure section 5 and the neutralizing lamp 2 include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, and a light emitting diode (LE).
D), semiconductor lasers (LD), electroluminescence (EL), and other general light-emitting materials can be used.
To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. Such a light source and the like include, in addition to the steps shown in FIG.
By providing a cleaning step or a step such as pre-exposure, the electrophotographic photosensitive member is irradiated with light.

The toner developed on the electrophotographic photosensitive member 1 by the developing unit 6 is transferred to the transfer paper 9, but not all of the toner is transferred, and toner remaining on the photosensitive member 1 is also generated. Such toner is removed from the photoconductor by the fur brush 14 and the blade 15. Cleaning may be performed only with a blade or a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush. However, when the developing unit is provided with a cleaning function, a cleaning unit such as the fur brush 14 and the blade 15 is not required.

When the electrophotographic photosensitive member according to the present invention is positively (negatively) charged and subjected to image exposure, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with a negative (positive) polarity toner (electrostatic detection fine particles), a positive image can be obtained. On the other hand, a negative image can be obtained by developing with positive (negative) polarity toner. A known method is applied to the developing unit, and a known method is also used for the charge removing unit.

FIG. 5 shows another example of the electrophotographic apparatus according to the present invention. The photoreceptor 21 has a photosensitive layer formed using a dispersion prepared by the above-described method, is driven by drive rollers 22a and 22b, is charged by a charger 23, is exposed to light by a light source 24, and is developed. (Not shown), transfer using the charger 25, exposure before cleaning by the light source 26, cleaning by the brush 27, and static elimination by the light source 28 are repeatedly performed. In FIG. 5, the photoconductor 21
(Of course, in this case, the support is translucent), and light irradiation for pre-cleaning exposure is performed from the support side.

The electrophotographic apparatus illustrated as above is an example of the embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 5, the pre-cleaning exposure is performed from the support side. However, the exposure may be performed from the photosensitive layer side, and the image exposure and the charge removal exposure may be performed from the support side.

On the other hand, the light irradiation step includes image exposure, pre-cleaning exposure, and charge removal exposure. However, in addition to this, a pre-transfer exposure, a pre-exposure of image exposure, and other known light irradiation steps are provided to provide a light Light irradiation can also be performed on the body.

The image forming means and steps as described in the above description of the electrophotographic apparatus include a copying machine, a facsimile,
The printer may be incorporated in the printer in the form of a process cartridge. What is a process cartridge?
Built-in photoreceptor, other charging means, exposure means, developing means,
This is one device (part) including a transfer unit, a cleaning unit, and a charge removing unit. There are many shapes and the like of the process cartridge. As a general example, a shape used in an Imagio MF200 (manufactured by Ricoh Company) as shown in FIG. 6 can be mentioned.

[0071]

Next, the present invention will be described with reference to examples.

Example 1 A coating liquid for an intermediate layer was prepared by dissolving 2 parts by weight of a polyamide resin (CM-8000: manufactured by Toray Industries, Inc.) in a mixed solvent of 20 parts by weight of n-butanol and 80 parts by weight of methanol. . This was applied on an aluminum drum having a diameter of φ30 mm and a length of 340 mm, and dried at 130 ° C. for 20 minutes to form an intermediate layer having a thickness of 0.5 μm. Next, 6.0 parts by weight of a disazo pigment represented by the following structural formula was added to a resin solution obtained by dissolving 1.2 parts by weight of polyvinyl butyral (Eslec BM-1: manufactured by Sekisui Chemical) in 150 parts by weight of methyl ethyl ketone. Dispersion was performed for 120 hours in a ball mill charged with zirconia balls (D × R = 71). After completion of the dispersion, 210 parts by weight of cyclohexanone was added and the mixture was dispersed for 3 hours to prepare a coating liquid for a charge generation layer. This is designated as coating liquid G-1. This coating solution G-1 was applied on the above-mentioned intermediate layer by a dip coating method, and dried to form a film having a thickness of 0.25
A μm charge generation layer was provided.

Embedded image Next, 7 parts by weight of a charge transport material represented by the following structural formula, polycarbonate (Z type: viscosity average molecular weight 30,000) 10
0.002 parts by weight of silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 83 parts by weight of tetrahydrofuran to prepare a coating liquid for a charge transport layer. This was applied on the charge generation layer and dried to form a charge transport layer having a thickness of 25 μm. Thus, an electrophotographic photosensitive member of Example 1 was obtained.

Embedded image

The coating liquid G-1 shown in Example 1 and the electrophotographic photosensitive member were evaluated as follows. First, the coating liquid was evaluated for particle diameter, viscosity, and coatability. The particle size is
The average particle size was measured at 5000 revolutions using CAPA500 (manufactured by Horiba, Ltd.). The viscosity was measured using an E-type viscometer (model:
ELD (manufactured by Tokyo Keiki Co., Ltd.) under the conditions of 20 ° C. and 100 rotations. About the coating liquid G-1, the average particle diameter was 0.35 μm and the viscosity was 2.4 cP. The coatability is
The number of foreign substances that were pigment non-dispersed materials having a diameter of 0.5 mm or more was visually measured for the applied charge generation layer. As a result, the number of the coating liquid G-1 was 0.

The evaluation of the image on the electrophotographic photosensitive member was made as follows.
The measurement was performed using Spirio 1510 (manufactured by Ricoh Co., Ltd.).
First, as an image evaluation, after running 20,000 sheets, the number of white spots of 0.5 mm or more on the black solid chart of A4 and the presence or absence of an abnormal image were evaluated. The electrophotographic photoreceptor of Example 1 had no black spots and no abnormal image. With respect to the above coating liquid and the electrophotographic photoreceptor, the coating liquid G-1 was subjected to room temperature (23 ± 2
゜ C) Evaluation was made for the cases where they were stored for 3 months and 6 months.

Example 2 The coating liquid of Example 2 was prepared in the same manner as in Example 1 except that the charge generating substance was dispersed with zirconia balls (D × R = 83) of φ14 mm. 2) and an electrophotographic photosensitive member were prepared and evaluated in the same manner as in Example 1.

Comparative Example 1 The coating liquid of Comparative Example 1 (H−) was prepared in the same manner as in Example 1 except that the charge generation material was dispersed with φ12 mm alumina balls (D × R = 48). 1) and an electrophotographic photosensitive member were prepared and evaluated in the same manner as in Example 1.

Table 1 shows the evaluation results of the above Examples and Comparative Examples.
Shown in

[Table 1]

Example 3 The coating liquid (G-3) of Example 3 and the electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the disazo pigment was replaced with an asymmetric disazo pigment having the following structural formula. To create
Evaluation was performed in the same manner as in Example 1.

Embedded image

Example 4 The coating liquid (G-4) of Example 4 and the electrophotographic photoreceptor were prepared in the same manner as in Example 3 except that the dispersion of the charge generating material was carried out with zirconia balls of φ14 mm. Was prepared and evaluated in the same manner as in Example 1.

Comparative Example 2 The coating liquid (H-2) and the electrophotographic photoreceptor of Comparative Example 2 were prepared in the same manner as in Example 3 except that the dispersion of the charge generating substance was carried out using alumina balls having a diameter of 12 mm. make,
Evaluation was performed in the same manner as in Example 1.

Comparative Example 3 The coating liquid (H-3) and the electrophotographic photoreceptor of Comparative Example 3 were prepared in the same manner as in Example 3 except that the dispersion of the charge generating substance was carried out using zirconia balls having a diameter of 10 mm. It was prepared and evaluated in the same manner as in Example 1.

Comparative Example 4 The coating liquid (H-4) of Comparative Example 4 and the electrophotographic photoreceptor were prepared in the same manner as in Example 3 except that the dispersion of the charge generating substance was carried out with zirconia balls of φ8 mm. make,
Evaluation was performed in the same manner as in Example 1.

Table 2 shows the evaluation results of Examples 3 and 4 and Comparative Examples 2 to 4.

[0084]

[Table 2]

[0085]

As is evident from the results obtained above,
In the present invention, by using a dispersion medium having a density and a diameter represented by the above formula (A), when coated, there are no coating film defects, excellent coating properties, and good stability. An electrophotographic photoreceptor coating solution that can provide an electrophotographic photoreceptor can be manufactured. In addition, by including a step of preparing a dispersion by dispersing in a solvent in the process of dispersing the dispersion medium, the production method according to the present invention has no coating film defects, and has excellent coatability and good stability. A photographic photoreceptor coating solution can be obtained. An electrophotographic photoreceptor prepared using an electrophotographic photoreceptor coating solution having such excellent properties can provide a high-quality image without image defects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration example of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a cross-sectional view illustrating another example of the configuration of the electrophotographic photosensitive member according to the present invention.

FIG. 3 is a sectional view showing another configuration example according to the present invention.

FIG. 4 is a cross-sectional view showing still another configuration example according to the present invention.

FIG. 5 is a schematic diagram for explaining an electrophotographic apparatus according to the present invention.

FIG. 6 is a schematic view showing one specific example of an electrophotographic apparatus to which the present invention is applied.

[Explanation of symbols]

Reference Signs List 11 conductive support 13 intermediate layer 15 photosensitive layer 17 charge generation layer 19 charge transport layer 21 protective layer 101 photosensitive drum 102 charging device 103 exposure 104 developing device 105 transfer member 106 transfer device 107 cleaning blade 108 discharging lamp 109 fixing device (105 : Transfer member, 106: transfer device, 108: static elimination lamp, 109: fixing device is not included in the cartridge portion.)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naohiro Toda 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H068 AA19 AA21 AA34 BA47 BA53 EA13 EA17 FA27

Claims (7)

[Claims] 1. A method for producing a coating liquid for an electrophotographic photosensitive member comprising at least an azo pigment dispersed in a solvent, wherein a dispersion medium for dispersing the pigment particles is represented by the following formula (A):
(D: g / cm ² ) and diameter (R: m)
m) A method for producing a coating liquid for an electrophotographic photosensitive member, characterized by having: D × R ≧ 65 (A) 2. The method for producing a coating liquid for an electrophotographic photosensitive member according to claim 1, wherein the dispersion medium is a zirconia ball. 3. The azo pigment according to the following general formula (I): Cp ₁ -N = N-AN = N-Cp ₂ (I) wherein A is an azo A divalent residue bonded to a nitrogen atom of the group; Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) The method for producing a coating liquid for an electrophotographic photosensitive member according to the above. 4. The coating liquid for an electrophotographic photoreceptor according to claim 3, wherein the asymmetric azo pigment represented by the general formula (I) is a compound represented by the following general formula (II). Production method. Embedded image (In the formula, Cp ₁ and Cp ₂ represent coupler residues having different structures from each other.) 5. An electrophotographic photoreceptor comprising a conductive support and at least a charge generation layer or a charge transport layer sequentially laminated thereon, wherein the charge generation layer is any one of claims 1 to 4. An electrophotographic photoreceptor formed using the electrophotographic photoreceptor coating liquid of (1). 6. An electrophotographic apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a discharging unit and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is
An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 5. 7. An electrophotographic process cartridge comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 5. Process cartridge for equipment.