JP2001265027A - Method for preparing coating fluid for electrophotographic photoreceptor and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a coating fluid for an electrophotographic photoreceptor free of defects in a coating film, excellent in suitability to coating and having good stability and to provide an electrophotographic photoreceptor manufactured with using the coating fluid and giving an image having no image defects and high image quality. SOLUTION: In the method for preparing the coating fluid for an electrophotographic photoreceptor by dispersing an azo pigment and a phthalocyanine pigment in at least a solvent, dispersion media for dispersing particles of the pigments comprise balls or beads having two or more different diameters.

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 photoreceptor, and more particularly to a method for producing a coating solution having no coating film defects and excellent coating properties. The present invention also relates to an electrophotographic photoreceptor which provides a high-quality image without image defects, which is prepared using the electrophotographic photoreceptor coating solution of the present invention.

[0002]

2. Description of the Related Art Conventionally, inorganic materials such as Se, CbS 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 photoreceptors using organic photoconductive materials have been actively developed, and electrophotographic photoreceptors having a photosensitive layer containing a charge generation material and a charge transport material have already been put to practical use. Has been reached. On the other hand, electrophotographic photoreceptors have a wide spectral sensitivity characteristic from visible to near-infrared region from the viewpoint of the emergence of electrophotographic devices using semiconductor lasers as light sources, such as laser printers and digital copiers, and the common use of photoconductors. Is starting to be required. Conventionally, two or more types of pigments having spectral sensitivity characteristics in different spectral regions have been used as charge generation materials for these photoconductors, for example, as disclosed in JP-A-63-1.
48264, JP-A-01-177553,
It is proposed in Japanese Patent Application Laid-Open No. 01-270060 and the like. .

[0003] However, by using two or more kinds of pigments as the charge generating material, the spectral sensitivity range is widened, but on the contrary, two or more energy levels are generated in the charge generating layer, so that the characteristics of the pigment itself are indispensable. It was difficult to achieve both a rise in residual potential and a fall in charge potential from the viewpoint of prescription. Further, when preparing a coating liquid using two or more pigments, there is no problem if the dispersion method suitable for each pigment is the same, but generally the dispersion method is different if the pigment is different, When two or more kinds of pigments are dispersed, problems such as coating film defects or shortening of the life of the coating liquid occur. Further, in the case of an organic pigment such as a phthalocyanine pigment, which tends to undergo a crystal transition, the crystal form changes due to slight touch of the dispersion conditions, the temporal stability of the dispersion differs, and the electrophotographic characteristics also vary depending on the dispersion batch. Also,
When the dispersion treatment time is extended, the coarse particles decrease, but the particles that have already been finely dispersed are excessively dispersed, so that the cohesiveness increases, and the diameter of the aggregated particles is likely to change during or after dispersion. This causes a problem that the stability of the dispersion liquid is remarkably deteriorated.

[0004] Various proposals have been made for dispersing methods to solve the above problems, but at present, satisfactory coating properties required for photoreceptor coating liquids have not been obtained. . That is, as distributed media,
JP-A-6-376672 discloses that the average particle size is 0.4.
It is described to use spherical media of ~ 0.8 mm,
Japanese Unexamined Patent Publication No. Hei 8-123045 describes that a crystalline glass medium is dispersed and that abrasion powder is prevented from being mixed into the medium. As a dispersing method, JP-A-1-176
No. 433, JP-A-1-176434 describes that dry pulverization is first performed, and a liquid is sent to the pulverization container and wet pulverization is performed there. JP-A-4-223272 discloses an organic pigment. It has been described that dry pulverization is performed beforehand using an alumina-based medium and then dispersed. JP-A-6-43762 discloses that an organic pigment is finely pulverized in a solvent in a spherical shape having an average particle diameter of 0.4 to 0.8 mm. JP-A-7-152188 describes that azo pigments are treated with 1,4-dioxane as a processing solvent and ball milling is performed.
No. 8, the coarse crystalline pigment is first subjected to dry milling,
It is described that the material is roughened by wet grinding in a stirring ball mill. Further, as an ultrasonic treatment, JP-A-60-178453 describes that the production, purification and dispersion of an azo pigment are performed under ultrasonic irradiation, and JP-A-61-170746 discloses a bisazo pigment. JP-A-63-30425 describes that a pigment is mechanically reduced to 0.1 μm or less and ultrasonically dispersed in a polar organic solvent.
No. 3 discloses that the azo pigment dispersion is subjected to ultrasonic treatment before being diluted with a solvent to a working concentration. In each of these publications, the pigment is limited to a phthalocyanine pigment or an azo pigment, or the crystal form changes in the case of dry pulverization like a phthalocyanine pigment. If the azo pigment is not hard, problems such as a change in characteristics due to dispersion occur.

[0005]

An object of the present invention is to solve the above-mentioned conventional problems. 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, in view of the above-mentioned prior art. . It is a further object of the present invention to provide an electrophotographic photoreceptor which provides a high-quality image free from image defects, prepared using the electrophotographic photoreceptor coating solution.

[0006]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the inventors of the present invention use two or more different diameter media as dispersion media for dispersing pigment particles. Alternatively, the present invention has been found to be able to solve the above problem by including a step of preparing a dispersion by dispersing in a solvent in a dispersion process and a step of performing ultrasonic irradiation on the dispersion to further uniformly disperse the dispersion. Was completed.

That is, according to the present invention, in the method for producing a coating liquid for an electrophotographic photosensitive member comprising at least an azo pigment and a phthalocyanine pigment dispersed in a solvent, a dispersion medium for dispersing the pigment particles is different. There is provided a method for producing a coating liquid for an electrophotographic photosensitive member, comprising a ball or a bead having two or more kinds of diameters. Furthermore, according to the present invention, in a method for producing a coating liquid for an electrophotographic photoreceptor comprising at least an azo pigment and a phthalocyanine pigment dispersed in a solvent, at least the azo pigment and the phthalocyanine pigment are pulverized by mechanical strain, A method for producing a coating liquid for an electrophotographic photosensitive member, comprising the steps of: preparing a dispersion liquid by dispersing the dispersion liquid therein, and irradiating the dispersion liquid with ultrasonic waves, and further uniformly dispersing the dispersion liquid. You. Further, according to the present invention, in the electrophotographic photoreceptor obtained by sequentially laminating at least a charge generation layer and a charge transfer layer on a conductive support, the charge generation layer comprises the electrophotographic photoreceptor coating solution of the present invention. And an electrophotographic photoreceptor characterized by being formed by using an electrophotographic photoreceptor.

Hereinafter, the present invention will be described in accordance with the structure of an electrophotographic photosensitive member. FIG. 1 is a cross-sectional view showing an example of the configuration of the electrophotographic photoreceptor of the present invention. The charge transport layer (19) formed by applying a coating liquid is laminated. FIG. 2 is a cross-sectional view showing another configuration example of the present invention, in which the conductive support (11) is shown.
An intermediate layer (13) is provided between and the charge generation layer (17). 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).

As the conductive support (11), those having conductivity of not more than 10 ¹⁰ Ω · cm, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver,
Metals such as platinum, tin oxide, metal oxides such as indium oxide, coated on film or cylindrical plastic or paper by evaporation or sputtering,
Or aluminum, aluminum alloy, nickel,
A plate made of stainless steel or the like and a tube subjected to surface treatment such as cutting, superfinishing, polishing, or the like after forming the tube by a method such as extrusion or drawing 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).

[0010] In addition, a support obtained by dispersing a conductive powder on a suitable binder resin on the above support and applying the same can also be used as the conductive support (11) of the present invention. This conductive powder includes carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper,
Metal powder such as zinc and silver, or metal oxide powder such as conductive titanium oxide, conductive tin oxide, and ITO may be used. The binder resin used simultaneously includes polystyrene, styrene-acrylonitrile copolymer, styrene-
Butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, Ethyl cellulose resin,
Thermoplastic, thermosetting or photo-setting resins such as polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin and alkyd resin Is mentioned. 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, heat shrinkage of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) or the like containing the conductive powder on a suitable cylindrical substrate. Also those that have a conductive layer provided by a tube,
It can be favorably used as the conductive support (11) of the present invention.

Examples of the charge generating material include phthalocyanine pigments such as titanyl phthalocyanine, vanadyl phthalocyanine, copper phthalocyanine, hydroxygallium phthalocyanine, and metal-free phthalocyanine as described in the present invention, monoazo pigments, bisazo pigments, asymmetric disazo pigments, and trisazo pigments. And azo pigments such as tetraazo pigments. Among these, it is particularly preferable to use a τ-type metal-free phthalocyanine pigment, an X-type metal-free phthalocyanine pigment, and a titanyl phthalocyanine pigment as the phthalocyanine pigment, and use a compound represented by the following general formula (I) as the azo pigment. Is preferred.

[0013]

Embedded image (Cp ₁ and Cp ₂ represent coupler residues having the same or different structures from each other.) Examples of Cp ₁ and Cp ₂ of these azo pigments are shown below.

[0014]

[Table 1-1]

[0015]

[Table 1-2]

[0016]

[Table 1-3]

[0017]

[Table 1-4]

[0018]

[Table 1-5]

[0019]

[Table 1-6]

[0020]

[Table 1-7]

The τ-type metal-free phthalocyanine pigment is Cu-K
In an X-ray diffraction spectrum using an α characteristic X-ray (wavelength: 1.541 °), the main peak at a Bragg angle of 2θ was 7.6.
°, 9.2 °, 16.8 °, 17.4 °, 20.4 °,
20.9 °, 21.7 °, 27.6 ° (± 0.2 each)
2 °), which is a metal-free phthalocyanine pigment present in JP-A-58-182639 and JP-A-60-1915.
It can be obtained by the method described in JP-A No. 4 (Kokai) No. 4 and the like.

X type metal-free phthalocyanine pigment is Cu-K
In the X-ray diffraction spectrum using the α characteristic X-ray (wavelength 1.541 °), the main peak at the Bragg angle 2θ was 7.5.
°, 9.1 °, 16.7 °, 17.3 °, 22.3 °,
It is a metal-free phthalocyanine pigment existing at 28.8 ° (each ± 0.2 °) and described in US Pat. No. 3,579,899, US Pat. No. 3,594,163, and JP-B-49-43.
No. 38, JP-A-60-243089 and the like.

Although various crystal forms of titanyl phthalocyanine have been known, titanyl phthalocyanine used in the present invention is not particularly limited. For example, an amorphous form, usually X-ray diffraction using Cu-Kα ray In the spectrum, Bragg angle (2θ ± 0.2 °) 7.6
Α having main peaks at °, 25.3 ° and 28.6 °
Shape, usually 9.3 °, Bragg angle (2θ ± 0.2 °) 9.3 °, 1
Β-form having main peaks at 3.3 ° and 26.3 °, usually 7.0 °, 15.6 at Bragg angle (2θ ± 0.2 °)
C having main peaks at °, 23.4 °, 25.5 °
Shape, usually 9.5 °, Bragg angle (2θ ± 0.2 °), 2
It shows peaks at 4.1 ° and 27.3 °, of which 27.
Examples include a crystal form having the highest diffraction peak intensity at 3 °. Among them, amorphous type, β type and Bragg angle (2θ ± 0.2 °) 9.5 °, 24.1 °, 27.3 °
And the crystal form having the highest intensity of the diffraction peak at 27.3 ° is preferable. Further, the X-ray diffraction spectrum shows a Bragg angle (2θ ± 0.2 °) of 9.5 °,
Usually, peaks are shown at 4.1 ° and 27.3 °, and among them, a crystalline form of titanyl phthalocyanine called a Y-form having the highest intensity of a diffraction peak at 27.3 ° is most preferable.

The reason why these pigments are preferable is not clear, but the compound represented by the above formula (I) is excellent in dispersibility, sensitivity and potential stability. Also for these phthalocyanine pigments, the HOMO level is close to the HOMO level of the asymmetric disazo, and the sensitizing effect produced by mixing the pigments by interacting with each other is effectively generated. It is thought that problems such as decline are less likely to occur.

The charge generation layer (17) comprises a ball mill containing at least an azo pigment and a phthalocyanine pigment in a suitable solvent.
It is formed by dispersing using an attritor, sand mill, ultrasonic wave or the like to form a coating liquid, applying the coating liquid on the conductive support (11) or the intermediate layer (13), and drying the coating liquid. As shown in the above, it is preferable that the dispersion medium for dispersing the pigment particles is composed of balls or beads of two or more different diameters, and that the azo pigment and the phthalocyanine pigment are It is preferable to include a step of pulverizing with a strain force and dispersing in a solvent to form a dispersion, and a step of irradiating the dispersion with ultrasonic waves and dispersing the dispersion more uniformly. By preparing a coating liquid according to the method shown in the present invention, it is possible to disperse both the azo pigment and the phthalocyanine pigment well. Problems such as defects in electrical characteristics and deterioration of coating properties such as coating film defects due to undispersed pigment when either one becomes poorly dispersed do not occur.

The material of the dispersion medium that can be used 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 3 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%) is used, but glass is easily broken in terms of strength and easily remains as a foreign substance in the coating solution, and alumina itself also wears during dispersion of the medium, and also easily remains in the coating solution as impurities. Therefore, it is preferable to use zirconia or titania-based media.

Regarding the diameter of the dispersion medium, as shown in the present invention, it is preferable to use two kinds of media, a medium having a diameter of 12 to 8 mm and a medium having a diameter of 4 to 0.3 mm. By using a medium having such a size, the effect of the present invention becomes more remarkable, and the above-mentioned problem is further reduced.

In the present invention, it is indicated that it is preferable to use both the dispersion method using mechanical strain force and the dispersion method using ultrasonic waves, such as a ball mill, but the ultrasonic wave used in the present invention is preferably used. The frequency is 10 to 10
0 kHz is preferred. When the frequency is lower than 10 kHz, the cavitation intensity is weakened, the dispersing ability is reduced, and the effect of the ultrasonic wave cannot be obtained. On the other hand, if the frequency is higher than 100 kHz, the cavitation intensity is large, so that the crystal form of the pigment changes, which has a bad influence on the electrostatic characteristics. A more preferable frequency range is 15 to 60 kHz, which has an ultrasonic effect and does not change the pigment crystal system. Further, the application time of the ultrasonic wave to the coating liquid is preferably from 1 minute to 30 minutes.
When the time is 1 minute or less, the effect of the present invention is not seen, and when the time is 30 minutes or more, aggregation or change in crystal form due to overdispersion occurs.

Although it is not clear why the dispersion method shown in the present invention is preferred, azo pigments generally require mechanical strain for dispersion, whereas phthalocyanine pigments require more mechanical force than necessary. When a mechanical strain is applied, the crystal form tends to change, and the sensitivity and residual potential tend to change due to electrostatic characteristics. It is considered that by using the dispersion method of the present invention, both pigments could be dispersed without any adverse effect.

As the binder resin used for the charge generation layer (17), polyamide, polyurethane, epoxy resin,
Polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl formal, polyvinyl ketone,
Polystyrene, poly-vinyl carbazole, polyacrylamide, polyvinyl butyral, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl Pyrrolidone and the like can be used.

The amount of the binder resin is 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.
Parts by weight are appropriate. The thickness of the charge generation layer is 0.01 to 5
μm, preferably 0.1 to 2 μm. Solvents used in preparing the charge generating layer coating liquid include methanol, ethanol n-butanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane And monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. The coating method of the coating solution includes dip coating, spray coating, bead coating, nozzle coating, spinner coating,
A method such as a ring coat can be used.

The charge transporting layer (19) can be formed by dissolving or dispersing the charge transporting substance and the binder resin in a suitable solvent, applying this on the charge generating layer, and drying. If necessary, a plasticizer, a leveling agent and the like can be added.

The charge transport material includes a hole transport material and an electron transport material. Examples of the electron transporting substance include chloranil, bromanil, 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-
Electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

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 derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
-Known materials such as styryl anthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and other polymerized hole transport materials.

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, 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 based on 100 parts by weight of the binder resin.
Suitably, parts by weight, preferably 40 to 150 parts by weight, are suitable.
The thickness of the charge transport layer is preferably about 5 to 50 μm.

As the solvent used here, tetrahydrofuran, dioxane, dioxolan, toluene, xylene, monochlorobenzene, dichloroethane, dichloromethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

In the present invention, a leveling agent may be added to the charge transport layer (19). As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain can be used. -1 part by weight is suitable. Further, an antioxidant may be added. As the antioxidant, an antioxidant such as a binder phenol compound, a sulfur compound, a phosphorus compound, a hindered amine compound, a pyridine derivative, a piperidine derivative, and a morpholine derivative is used. it can.

To the intermediate layer (13), a fine powder pigment of a metal oxide such as titanium oxide, aluminum oxide, silica, zirconium oxide, tin oxide or indium oxide is added to prevent moiré and reduce residual potential. You may. 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,
Titanyl alkoxide compounds and organic titanyl compounds can also be used. These intermediate layers (13) can be formed using an appropriate solvent, dispersion and coating method as in the above-mentioned photosensitive layer.

In addition, the intermediate layer (13) of the present invention includes:
Al ₂ O ₃ provided by anodic oxidation, organic substances such as polyparaxylylene, SiO ₂ , SnO ₂ , TiO ₂ , IT
Those provided with an inorganic substance such as O or CeO ₂ by a vacuum thin film forming method can also be used favorably. The thickness of the intermediate layer (13) is 0 to 1
0 μm is appropriate.

The protective layer (21) is provided for the purpose of improving the durability of the photoconductor, and the material used for this is ABS.
Resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide,
Polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate,
Polyether sulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide,
Polysulfone, polystyrene, AS resin, butadiene
Resins include styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin and the like.

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 do. As a method for forming the protective layer (21), a normal coating method can be used. The thickness of the protective layer (21) is suitably from 0.1 to 10 μm. In addition to the above, known materials such as aC and a-SiC formed by a vacuum thin film forming method can also be used as the protective layer (21).

In the present invention, another intermediate layer (not shown) can be provided between the photosensitive layer (15) and the protective layer (21). The other intermediate layer is generally used 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 another intermediate layer, a normal coating method can be used as described above. The thickness is 0.05 to 2 μm.
m is appropriate.

[0043]

Next, the present invention will be described with reference to examples. (Example 1) Titanium oxide (CR-EL: manufactured by Ishihara Sangyo) 7
0 parts by weight, alkyd resin (Beccolite M6401-
50-S (solid content: 50%): manufactured by Dainippon Ink and Chemicals
15 parts by weight, melamine resin (Super Beckamine L-1)
A mixture comprising 10 parts by weight of 21-60 (solid content 60%: manufactured by Dainippon Ink and Chemicals, Inc.) and 100 parts by weight of methyl ethyl ketone was dispersed in a ball mill for 72 hours to prepare a coating liquid for an intermediate layer. This is φ30mm in diameter and 340m in length
m, and dried at 130 ° C. for 20 minutes to form an intermediate layer having a thickness of 4.5 μm. Next, 4.0 parts by weight of a disazo pigment represented by the following structural formula (II) and 2.0 parts by weight of a τ-type metal-free phthalocyanine pigment were mixed with polyvinyl butyral (Eslec BM-S: manufactured by Sekisui Chemical).
2.4 parts by weight were added to a resin solution prepared by dissolving 150 parts by weight of methyl ethyl ketone.
A 2 mm PSZ ball was dispersed in a pot at a weight ratio of 2: 1 in a ball mill for 240 hours. After the dispersion was completed, 210 parts by weight of cyclohexanone was added and the mixture was dispersed for 3 hours to prepare a charge generation layer coating solution. The average particle size of this coating solution was measured using CAPA700 (manufactured by Horiba, Ltd.). Further, a coating solution was applied on the intermediate layer and dried at 130 ° C. for 10 minutes to form a 0.25 μm-thick charge generating layer. For the coated charge generation layer, φ0.
The number of non-pigmented foreign materials having a size of 5 mm or more was visually measured. Next, 7 parts by weight of a charge transport material represented by the following structural formula (III), 10 parts by weight of polycarbonate (Z type: viscosity average molecular weight 30,000), and silicone oil (KF-
50: manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 100 parts by weight of tetrahydrofuran to prepare a coating solution for the charge transport layer. This is applied on the charge generation layer, and
The resultant was dried at 15 ° C. for 15 minutes to form a charge transport layer having a thickness of 25 μm.

[0044]

Embedded image

[0045]

Embedded image

(Example 2) In Example 1, the dispersion of the charge generating material was changed to a φ10 mm PSZ ball and a φ2 mm PZ ball.
Instead of using SZ balls at a 2: 1 weight ratio, φ1
An evaluation of Example 2 and an electrophotographic photoreceptor were made in the same manner as in Example 1, except that a 0 mm PSZ ball and a φ1 mm PSZ ball were used at a weight ratio of 2: 1.

(Example 3) In Example 1, the dispersion of the charge generating material was changed to a φ10 mm PSZ ball and a φ2 mm PZ ball.
Instead of using SZ balls at a 2: 1 weight ratio, φ1
An evaluation of Example 3 and an electrophotographic photoreceptor were made in the same manner as in Example 1 except that a 2 mm PSZ ball and a φ2 mm PSZ ball were used at a weight ratio of 2: 1.

(Example 4) In Example 1, the dispersion of the charge generating material was changed to a φ10 mm PSZ ball and a φ2 mm PZ ball.
Instead of using SZ balls at a 2: 1 weight ratio, φ1
An evaluation of Example 4 and an electrophotographic photoreceptor were made in the same manner as in Example 1, except that a 0 mm PSZ ball and a φ0.5 mm PSZ ball were used at a weight ratio of 2: 1.

(Comparative Example 1) In Example 1, the dispersion of the charge-generating substance was changed to a PSZ ball having a diameter of 10 mm and a PZ ball having a diameter of 2 mm.
Instead of using SZ balls at a 2: 1 weight ratio, φ1
An evaluation of Comparative Example 1 and an electrophotographic photoreceptor were made in the same manner as in Example 1 except that dispersion was performed only with a 0 mm PSZ ball.

(Comparative Example 2) In Example 1, the dispersion of the charge generating substance was changed to a PSZ ball having a diameter of 10 mm and a PZ ball having a diameter of 2 mm.
Instead of using SZ balls in a 2: 1 weight ratio, φ2
Comparative Example 2 and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the dispersion was performed only with the PSZ ball having a diameter of 2 mm.

Comparative Example 3 In Comparative Example 1, instead of 4.0 parts by weight of the disazo pigment and 2.0 parts by weight of the τ-type metal-free phthalocyanine pigment represented by the structural formula (II), τ-type metal-free phthalocyanine was used. Comparative Example 1 except that 0 parts by weight was used.
In the same manner as in the above, an evaluation of Comparative Example 3 and an electrophotographic photosensitive member were prepared.

Comparative Example 4 In Comparative Example 2, instead of 4.0 parts by weight of the disazo pigment represented by the structural formula (II) and 2.0 parts by weight of the τ-type metal-free phthalocyanine pigment, τ-type metal-free phthalocyanine 6. Comparative Example 2 except that 0 parts by weight was used.
Comparative Example 4 and an electrophotographic photosensitive member were prepared in the same manner as in the above.

The electrophotographic photosensitive member obtained as described above is used in a digital copying machine, IMAZIO MF2200.
An image was evaluated with a filter having an ND of 0.5 attached to the exposed portion using (manufactured by Ricoh Co., Ltd.), and reducing the amount of exposure light to half. First, as the image evaluation, 20,000 sheets of paper running were performed, and then black spots of 0.5 mm or more were rated as A.
No. 4 was evaluated for the number appearing on white paper and for the occurrence of other abnormal images.

[0054]

[Table 2]

Example 5 The evaluation of Example 5 and the electrophotographic photoreceptor were carried out in the same manner as in Example 1, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

(Example 6) The evaluation of Example 6 and the electrophotographic photoreceptor were carried out in the same manner as in Example 1 except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

Comparative Example 5 The evaluation of Comparative Example 5 and the electrophotographic photoreceptor were carried out in the same manner as in Comparative Example 1, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

Comparative Example 6 The evaluation of Comparative Example 6 and the electrophotographic photoreceptor were performed in the same manner as in Comparative Example 2, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

(Example 7) In Example 1, the following structural formula (IV) was used instead of the disazo pigment represented by the structural formula (II).
The evaluation of Example 7 and the preparation of an electrophotographic photoreceptor were carried out in the same manner as in Example 1 except that the disazo pigment shown in Table 1 was used.

[0060]

Embedded image

Example 8 In Example 2, the disazo pigment represented by the structural formula (II) was replaced with the structural formula (IV)
The evaluation of Example 8 and the preparation of an electrophotographic photoreceptor were carried out in the same manner as in Example 2 except that the disazo pigment shown in Table 1 was used.

Comparative Example 7 In Comparative Example 1, the disazo pigment represented by the structural formula (II) was replaced with the structural formula (IV)
The evaluation of Example 8 and the preparation of an electrophotographic photoreceptor were carried out in the same manner as in Comparative Example 1 except that the disazo pigment shown in Table 1 was used.

Comparative Example 8 In Comparative Example 2, the disazo pigment represented by the structural formula (II) was replaced with the structural formula (IV)
Comparative Example 8 and an electrophotographic photoreceptor were prepared in the same manner as in Comparative Example 2, except that the disazo pigment shown in Table 1 was used.

Example 9 The evaluation of Example 9 and the electrophotographic photoreceptor were performed in the same manner as in Example 7, except that the X-type metal-free phthalocyanine was used instead of the τ-type metal-free phthalocyanine. Created.

Example 10 The evaluation of Example 10 and the electrophotographic photoreceptor were performed in the same manner as in Example 8, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

Comparative Example 9 The evaluation of Comparative Example 9 and the electrophotographic photoreceptor were performed in the same manner as in Comparative Example 7, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

Comparative Example 10 The evaluation of Comparative Example 10 and the electrophotographic photoreceptor were carried out in the same manner as in Comparative Example 8, except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine. Created.

Example 11 Example 11 was repeated in the same manner as in Example 7 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Example 12 Example 12 was repeated in the same manner as in Example 8 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Comparative Example 11 Comparative Example 11 was performed in the same manner as in Comparative Example 7, except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Comparative Example 12 Comparative Example 12 was performed in the same manner as in Comparative Example 8 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Example 13 Example 13 was repeated in the same manner as in Example 7, except that Y-type titanyl phthalocyanine was used instead of the τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Example 14 Example 14 was carried out in the same manner as in Example 8, except that Y-type titanyl phthalocyanine was used instead of the τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Comparative Example 13 Comparative Example 13 was carried out in the same manner as in Comparative Example 7 except that Y-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared.

Comparative Example 14 Comparative Example 14 was performed in the same manner as in Comparative Example 8 except that Y-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine.
And an electrophotographic photosensitive member was prepared. Table 3 shows the evaluation results of Examples 5 to 14 and Comparative Examples 5 to 14 obtained as described above.

[0076]

[Table 3]

(Embodiment 15) In the same manner as in Embodiment 1, φ3
An intermediate layer was formed on an aluminum drum having a length of 0 mm and a length of 340 mm. Next, 4.0 parts by weight of the disazo pigment represented by the structural formula (IV) and 2.tau.
0 parts by weight of polyvinyl butyral (Eslec BM-
S: Sekisui Chemical) 2.4 parts by weight of methyl ethyl ketone 1
Added to the resin solution dissolved in 50 parts by weight,
Dispersion was performed for 240 hours in a ball mill charged with SZ balls in a pot. After the dispersion, cyclohexanone 21
0 parts by weight were added and the mixture was dispersed for 3 hours, and the dispersion was further ultrasonically dispersed in an ultrasonic cleaning layer of 28 kHz and 500 W for 5 minutes to prepare a coating liquid for a charge generation layer. The average particle size of this coating solution was measured using CAPA700 (manufactured by Horiba, Ltd.). Further, a coating liquid is applied on the intermediate layer, and dried at 130 ° C. for 10 minutes to form a film having a thickness of 0.25 μm
Was formed. 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. Next, 7 parts by weight of the charge transport material represented by the structural formula (III), polycarbonate (Z type:
10 parts by weight of a viscosity average molecular weight (30,000) and 0.002 parts by weight of silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in 100 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 at 130 ° C. for 15 minutes to form a charge transport layer having a thickness of 25 μm. Thus, an electrophotographic photoreceptor of Example 1 was obtained.

Example 16 Example 1 was the same as Example 15 except that the output of the ultrasonic wave was 10 kHz and 500 W.
In the same manner as in Example 5, an evaluation of Example 16 and an electrophotographic photosensitive member were prepared.

(Embodiment 17) Embodiment 1 is the same as Embodiment 15 except that the output of the ultrasonic wave is set to 20 kHz and 500 W.
In the same manner as in Example 5, the evaluation of Example 17 and the electrophotographic photosensitive member were prepared.

(Embodiment 18) Embodiment 1 is the same as Embodiment 15 except that the output of the ultrasonic wave is set to 44 kHz and 500 W.
In the same manner as in Example 5, an evaluation of Example 16 and an electrophotographic photosensitive member were prepared.

(Example 19) Example 1 was repeated except that the ultrasonic wave output in Example 15 was changed to 60 kHz and 500 W.
In the same manner as in Example 5, an evaluation of Example 19 and an electrophotographic photosensitive member were prepared.

Example 20 An evaluation and an electrophotographic photosensitive member of Example 20 were made in the same manner as in Example 15 except that the output of the ultrasonic wave was changed to 100 kHz and 500 W.

Comparative Example 15 An evaluation of Comparative Example 15 and an electrophotographic photosensitive member were prepared in the same manner as in Example 15 except that the ultrasonic treatment was not performed.

Comparative Example 16 Evaluation of Comparative Example 16 was performed in the same manner as in Example 15 except that the milling time of the ball mill before adding cyclohexanone was changed to 2 hours and the ultrasonic treatment time was changed to 1 hour. And an electrophotographic photoreceptor was prepared.

Comparative Example 17 In Example 15, τ-type metal-free phthalocyanine was used instead of 4.0 parts by weight of disazo pigment and 2.0 parts by weight of τ-type metal-free phthalocyanine pigment represented by the structural formula (IV). An evaluation of Comparative Example 17 and an electrophotographic photosensitive member were prepared in the same manner as in Example 15 except that 0 parts by weight was used.

Comparative Example 18 In Example 15, instead of 4.0 parts by weight of the disazo pigment represented by the structural formula (IV) and 2.0 parts by weight of the τ-type non-metallic phthalocyanine pigment, the disazo pigment of the structural formula (IV) was used. An evaluation of Comparative Example 18 and an electrophotographic photoreceptor were made in the same manner as in Example 15, except that 6.0 parts by weight of the pigment was used.

Example 21 Example 2 was repeated in the same manner as in Example 15 except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine.
Evaluation 1 and an electrophotographic photosensitive member were prepared.

Example 22 Example 2 was repeated in the same manner as in Example 18 except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine.
2 and an electrophotographic photosensitive member was prepared.

Comparative Example 19 Comparative Example 1 was performed in the same manner as in Comparative Example 15 except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine.
9 and an electrophotographic photosensitive member was prepared.

Comparative Example 20 Comparative Example 2 was carried out in the same manner as in Comparative Example 16 except that X-type metal-free phthalocyanine was used instead of τ-type metal-free phthalocyanine.
An evaluation of 0 and an electrophotographic photosensitive member were prepared.

Example 23 Evaluation of Example 23 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Example 15 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

Example 24 Evaluation of Example 24 and preparation of an electrophotographic photoreceptor were performed in the same manner as in Example 18, except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

Comparative Example 21 Evaluation of Comparative Example 21 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Comparative Example 15 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

Comparative Example 22 Evaluation of Comparative Example 22 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Comparative Example 16 except that β-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

Example 25 Evaluation of Example 25 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Example 15, except that Y-type titanyl phthalocyanine was used in place of τ-type metal-free phthalocyanine. did.

Example 26 Evaluation of Example 26 and preparation of an electrophotographic photoreceptor were carried out in the same manner as in Example 18, except that Y-type titanyl phthalocyanine was used instead of the τ-type metal-free phthalocyanine. did.

Comparative Example 23 Evaluation of Comparative Example 23 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Comparative Example 15 except that Y-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

Comparative Example 24 Evaluation of Comparative Example 24 and preparation of an electrophotographic photosensitive member were performed in the same manner as in Comparative Example 16 except that Y-type titanyl phthalocyanine was used instead of τ-type metal-free phthalocyanine. did.

(Example 27) In Example 15, the structural formula (I) was used instead of the disazo pigment represented by the structural formula (IV).
An evaluation of Example 27 and an electrophotographic photoreceptor were made in the same manner as in Example 15, except that the disazo pigment shown in I) was used.

(Example 28) In Example 17, the above-mentioned structural formula (I) was used instead of the disazo pigment represented by the structural formula (IV).
The evaluation of Example 28 and the preparation of an electrophotographic photosensitive member were carried out in the same manner as in Example 17, except that the disazo pigment shown in I) was used.

(Example 29) In Example 18, the above-mentioned structural formula (I) was used instead of the disazo pigment represented by the structural formula (IV).
An evaluation of Example 29 and an electrophotographic photoreceptor were made in the same manner as in Example 18, except that the disazo pigment shown in I) was used.

(Example 30) In Example 19, the structural formula (I) was used in place of the disazo pigment represented by the structural formula (IV).
An evaluation of Example 30 and an electrophotographic photoreceptor were made in the same manner as in Example 19 except that the disazo pigment shown in I) was used.

Comparative Example 25 In Comparative Example 15, the structural formula (I) was used instead of the disazo pigment represented by the structural formula (IV).
An evaluation of Comparative Example 25 and an electrophotographic photoreceptor were made in the same manner as in Comparative Example 15 except that the disazo pigment shown in I) was used.

Comparative Example 26 In Comparative Example 16, the structural formula (I) was used instead of the disazo pigment represented by the structural formula (IV).
An evaluation of Comparative Example 26 and an electrophotographic photoreceptor were made in the same manner as in Comparative Example 16 except that the disazo pigment shown in I) was used. As described above, the obtained Examples 15 to 30 and Comparative Examples 15 to
Table 4 shows the evaluation results of No. 26.

[0105]

[Table 4] * 1: Not evaluated because there is no light sensitivity at 780 nm

[0106]

As described above, it is clear from the detailed and concrete description that two or more kinds of different media having different diameters are used as a dispersion medium for dispersing the pigment particles according to the present invention. The step of preparing a dispersion by dispersing in a solvent and performing the ultrasonic irradiation on the dispersion to further uniformly disperse, the coating film defect by a method for producing a coating solution for an electrophotographic photoreceptor, It is possible to obtain a coating solution for an electrophotographic photoreceptor that is excellent in coating properties and exhibits good stability, and has high image quality without image defects created using the electrophotographic photoreceptor coating solution. This provides an excellent effect that an electrophotographic photosensitive member giving an image can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a layer configuration of an electrophotographic photosensitive member shown in the present invention.

FIG. 2 is a cross-sectional view illustrating a layer configuration of the electrophotographic photosensitive member shown in the present invention.

FIG. 3 is a cross-sectional view illustrating a layer configuration of the electrophotographic photosensitive member shown in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 conductive support 13 intermediate layer 15 charge generation layer 17 charge transport layer 21 protective layer

Continued on front page (72) Inventor Tatehiko Kinoshita 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H068 AA19 AA34 AA37 BA38 BA39 BA41 BA47 EA13

Claims (7)

[Claims] 1. A method for producing a coating liquid for an electrophotographic photosensitive member comprising at least a azo pigment and a phthalocyanine pigment dispersed in a solvent, wherein the dispersion medium for dispersing the pigment particles has two or more different diameters. A method for producing a coating liquid for an electrophotographic photoreceptor, comprising a ball or a bead as described above. 2. The method according to claim 1, wherein the dispersion medium has a diameter of 12 mm to 8 mm.
2. The method for producing a coating liquid for an electrophotographic photosensitive member according to claim 1, wherein the coating liquid comprises two types: a liquid having a diameter of 4 mm and a diameter of 4 mm to 0.3 mm. 3. A method for producing a coating liquid for an electrophotographic photosensitive member comprising at least a azo pigment and a phthalocyanine pigment dispersed in a solvent, wherein at least the azo pigment and the phthalocyanine pigment are pulverized by mechanical strain and dispersed in the solvent. A method for producing a coating liquid for an electrophotographic photoreceptor, comprising the steps of: preparing a dispersion liquid; and irradiating the dispersion liquid with ultrasonic waves to further disperse the dispersion liquid. 4. The frequency of the ultrasonic wave is 15 to 60 kHz.
The method for producing a coating liquid for an electrophotographic photoreceptor according to claim 3, wherein: 5. The method for producing a coating liquid for an electrophotographic photosensitive member according to claim 1, wherein the azo pigment is a compound represented by the following general formula (I). . Embedded image (Cp ₁ and Cp ₂ represent coupler residues having the same or different structures from each other.) 6. The phthalocyanine pigment is a τ-type metal-free phthalocyanine pigment, an X-type metal-free phthalocyanine pigment,
The method for producing a coating liquid for an electrophotographic photosensitive member according to any one of claims 1 to 5, wherein the pigment is a kind of pigment selected from titanyl phthalocyanine pigments. 7. An electrophotographic photoreceptor in which at least a charge generation layer and a charge transfer layer are sequentially laminated on a conductive support, wherein the charge generation layer according to any one of claims 1 to 6 An electrophotographic photoreceptor formed using an electrophotographic photoreceptor coating solution.