JPH09211873A - Production of coating liquid for producing electrophotographic photoreceptor and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a pigment-contg. dispersion liq. for an electrophotographic photoreceptor excellent in suitability to coating and having satisfactory stability and to obtain an electrophotographic photoreceptor having high sensitivity and excellent in repetitive characteristics by using the coating liq. SOLUTION: When pigment particles for an electrophotographic photoreceptor, together with a binder, are dispersed in a solvent to produce a coating liq. for producing an electrophotographic photoreceptor, at least one kind of dispersive medium selected from among soda glass beads, low alkali glass beads and yttria-contg. zirconia beads is used as a dispersive medium for dispersing the pigment particles.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a coating liquid for producing an electrophotographic photoreceptor having excellent coatability and good stability, and high sensitivity and excellent repetitive properties using this coating liquid. The present invention relates to an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer containing an inorganic photoconductor as a main component such as selenium, cadmium sulfide, zinc oxide, and silicon are widely known. However, they are not always satisfactory in sensitivity, thermal stability, moisture resistance, durability and the like, and in particular, selenium and cadmium sulfide have restrictions in production and handling due to their toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages, such as better thermal stability than the body, and has received much attention in recent years.

[0004] Such organic photoconductive compounds include:
Poly-N-vinyl carbazole is well known, and has an electrophotographic photosensitive member having a photosensitive layer mainly composed of a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. Body is 50-5049
No. 6 is described. However, this photoreceptor was not always satisfactory in sensitivity, film-forming property, and durability.

On the other hand, electrophotographic photosensitive materials containing a low-molecular-weight organic photoconductor obtained by combining a charge transfer agent represented by triphenylamines, stilbenes and hydrazones with a charge generating agent such as phthalocyanine and azo pigment. The body has been proposed. By combining these with an appropriate binder, and further combining a compound having a high charge generation ability and a compound having a high charge transfer ability, for example, as a laminated type photoreceptor, a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium has appeared. There is. As a result, photoconductors containing such an organic photoconductive compound as a main component have largely entered the field of copying machines and printers.

When an organic material is coated on a conductive support, a solvent-soluble constituent substance such as a resin can be dissolved in the solvent and applied, but a pigment or the like is generally insoluble in the solvent. Since such constituent substances cannot be applied as they are, a method of dispersion is necessary. Dispersion described here is to make the pigment, etc., into fine particles in a solvent to make it a suspended state without sediment, and the stability of dispersion means that the particle size is uniform and stable in the solvent for a long time. Means saved.

When the dispersibility of the pigment is deteriorated, the coated surface becomes rough, which causes image defects such as pinholes and uneven density. In addition, the dispersed particles settle out over time and the concentration of the dispersion becomes non-uniform, resulting in uneven image density, and the viscosity of the dispersion causes fluctuations in the coating amount, leading to lower productivity. .

In order to obtain a good pigment dispersion, a method of controlling the aggregation state by changing a part of the molecular structure of the pigment or mixing pigments having different structures, or using a solvent on the surface of the pigment There is a method of adsorbing a soluble resin. However, in these methods, the electrophotographic properties of the original pigment, that is, the sensitivity and the repetitive property are changed, and a situation has emerged in which the basic purpose of the pigment cannot meet its initial purpose as a photoreceptor.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for producing a pigment dispersion for an electrophotographic photoreceptor which has excellent coatability and good stability, and a highly sensitive and repetitive property using this coating solution. To provide an excellent electrophotographic photoreceptor.

[0010]

DISCLOSURE OF THE INVENTION As a result of various investigations by the present inventors in order to achieve the above object, an electrophotographic photoreceptor obtained by dispersing pigment particles for an electrophotographic photoreceptor together with a binder in a solvent. In the method for producing a coating liquid for production, the dispersion medium for dispersing the pigment particles for electrophotographic photoreceptor may be soda glass beads, low alkali glass beads, or at least one dispersion medium selected from yttria-containing zirconia beads. The present invention has been found to be effective and has led to the present invention.

The present invention also uses the above-mentioned coating liquid for producing an electrophotographic photosensitive member as a charge generating layer of an electrophotographic photosensitive member comprising a conductive support and at least a charge generating layer and a charge transfer layer sequentially laminated on the conductive support. The inventors have found that the formed electrophotographic photosensitive member is excellent, and completed the present invention.

Hereinafter, each component of the present invention will be described in detail.

The pigment particles for electrophotographic photoreceptors used in the present invention include azo pigments represented by monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene pigments and thiazole azo pigments, and perylene. Perylene pigments typified by acid anhydrides and perylene imides, anthraquinone derivatives, anthanitrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, anthraquinone derivatives such as violanthrone derivatives and isoviolanthrone derivatives, Examples include phthalocyanine pigments represented by ring quinone pigments, metal phthalocyanines, metal naphthalocyanines, metal-free phthalocyanines, and metal-free naphthalocyanines.

Of these, bisazo pigments, trisazo pigments, and phthalocyanine pigments, which have a particularly high carrier generation efficiency, are preferable because they give high sensitivity and provide an excellent photoreceptor. For example, in the case of a bisazo pigment, JP-A-62-286058 and JP-A-63-32
No. 557, No. 63-243948, No. 64-
The compounds described in JP-A 21453, JP-A 64-21455, JP-A-1-94350, JP-A 1-200267, and JP-A 1-2202757 can be used.

The above-mentioned pigment particles according to the present invention are dispersed in a solvent by a dispersing machine using a dispersing medium such as a ball mill, a vertical sand mill, a horizontal sand mill and a paint conditioner. Distributed media in the present invention means
It means a substance that is put into the above-mentioned disperser together with the pigment particles and gives a strong force to the pigment particles to pulverize and disperse them in the solvent. In the present invention, for example, an ultrasonic dispersion method, a roll mill, an impact mill or the like which does not use a dispersion medium is not used.

As the material of the dispersion medium according to the present invention, soda glass (SiO ₂ 70 to 73%, Na ₂ O 1
3% to 15%), low-alkali glass (SiO ₂ 42 to 52
%, Al ₃ O ₃ 13-23%, CaO 10-25%, C
aO + MgO 18 to 32%) and yttria-containing zirconia (ZrO ₂ 93 to 95%, Y ₂ O ₃ 4 to 6%). The shape of the dispersion medium is preferably a bead shape having a diameter of several mm. When a dispersion medium other than soda glass, low alkali glass, or yttria-containing zirconia is used as the material, for example, alumina (Al ₂ O ₃ ) that is said to have the same abrasion resistance as yttria-containing zirconia is used.
91-93%), titania (TiO ₂ 77.7%, Al
₂ O ₃ 17.4%, SiO ₂ 4.6%), zircon (Z
rO ₂ 68.5%, SiO ₂ 31%) and other electrophotographic photoreceptors having a charge generation layer formed by coating a pigment dispersion liquid produced using a dispersion medium, resulting in rough coating surface and image failure. Occurs and the sensitivity and repeatability are further deteriorated, and the effect of the present invention cannot be obtained.

Particularly in the present invention, the pigment dispersion liquid produced by using soda glass beads has extremely excellent dispersibility. It is considered that the alkaline component contained in the soda glass acts as a dispersant, and as a result, the dispersibility is improved.

The dispersant exhibits a wetting effect of lowering the interfacial tension of the pigment surface in the process of dispersing the pigment, and further has a dispersion stabilizing effect of appropriately controlling the agglomeration of the pigment particles by forming an electric charge or a steric hindrance around the pigment particles. Show.
Therefore, by using the dispersant, the dispersibility is improved and the pigment particles are less likely to aggregate.

Further, in particular, an electrophotographic photosensitive member having a charge generation layer formed by coating a pigment dispersion liquid using low-alkali glass beads exhibits extremely excellent electric characteristics. Although the cause of this is not yet clear, some interaction between the surface of the pigment particles and the dispersion medium may occur during the progress of the dispersion process, resulting in improvement of the electrical properties of the resulting charge generation layer. It is thought to be done.

As the binder according to the present invention, a polymer or copolymer of a vinyl compound such as styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester, etc.,
Examples thereof include silicone resins, phenoxy resins, butyral resins, formal resins, phenol resins, polycarbonates, polyarylates, polyamides, polyimides, epoxy resins, thermosetting resins such as urethane resins, and photocurable resins. The binder is used in an amount of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, based on 100 parts by weight of the pigment for electrophotographic photoreceptor. The thickness of the charge generation layer using the coating liquid for producing an electrophotographic photoreceptor according to the present invention is preferably 0.1 to 20 μm.

As the electroconductive support on which the photoconductor of the present invention is formed, any of those known in electrophotographic photoconductors can be used. Specifically, for example, gold,
Silver, platinum, titanium, aluminum, copper, zinc, iron,
Examples thereof include a drum, a sheet, a belt made of a metal oxide or the like that has been subjected to a conductive treatment, a laminate of these thin films, and a vapor deposit.

Further, a conductive substance such as metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt, and ion conductive polymer electrolyte is coated with a suitable binder to form a polymer matrix. Drums, sheets, belts, etc. made of plastic, ceramics, paper, etc. that have been embedded in and subjected to conductive treatment, and drums of plastics, ceramics, paper, etc. that have become conductive by containing such conductive substances, Examples include seats and belts.

A blocking layer may be provided between the photosensitive layer and the conductive support in order to control the injection of charges from the photosensitive layer to the conductive support. A surface layer may be provided to improve the temperature.

The charge transfer material used in the charge transfer layer according to the present invention includes a hole transfer material and an electron transfer material.
Examples of the former include, for example, oxadiazoles disclosed in JP-B-34-5466 and JP-B-45-55.
5, triphenylmethanes, Japanese Patent Publication No. 52-18888, pyrazolines, Japanese Patent Publication No. 55-42380, hydrazones, JP-A-56-123544. Oxadiazoles disclosed in the publication, triarylamines disclosed in JP-B-58-32372, JP-A-58-198.
Examples thereof include stilbenes disclosed in Japanese Patent No. 043. On the other hand, examples of the electron transporting substance include chloranil, tetracyanoethylene, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 1,3,7-trinitrodibenzothiophene and the like. There is. These charge transfer substances can be used alone or in combination of two or more.

Among these charge transfer substances, hydrazone compounds and stilbene compounds are preferable because they have high charge (hole) mobility and provide an excellent photoconductor. For example, in the case of a hydrazone compound, the above-mentioned Japanese Patent Publication No.
Japanese Patent Application Laid-Open No. 1-10
No. 0555, No. 2-10367, No. 2-51
No. 163, No. 2-96767, No. 2-183.
No. 260, No. 2-184856, No. 2-18
No. 4858, No. 2-184859, No. 2-2
The hydrazone compounds described in Japanese Patent No. 26160 can be used.

As the binder used in the charge transfer layer, polystyrene, acrylic resin represented by polymethylmethacrylate, polycarbonate resin having bisphenol A or Z skeleton, polyarylate resin, polyphenylene ether resin, polyether sulfone resin, polyamide A resin, a polyimide resin, a polyester resin, or the like can be used. Charge transfer material 1 in the charge transfer layer
The binder is used in the range of 10 to 400 parts by weight based on 00 parts by weight. The thickness of the charge transfer layer is 5 to 10
0 μm is preferred.

The electrophotographic photoreceptor of the present invention contains 2,6-di-te in order to prevent deterioration of constituent organic compounds due to oxidation.
An antioxidant such as rt-butyl-p-cresol or DL-α-tocopherol may be added. In addition,
Well-known plasticizers may be used to improve flexibility and mechanical strength.

In the present invention, the pigment is used by dispersing it in a solvent and dissolving the dye, binder and charge transfer substance. Solvents used are chloroform, dichloromethane, dichloroethane, trichloroethane, halogenated hydrocarbons such as trichloroethylene, benzene, toluene, aromatic hydrocarbons such as xylene, dioxane, tetrahydrofuran, ether such as dimethoxyethane,
Solvents such as cellosolve solvents such as methyl cellosolve, dimethyl cellosolve, and methyl cellosolve acetate, or a mixed solvent of two or more kinds thereof, or if necessary, alcohols, acetonitrile, N, N-dimethylformamide,
A solvent such as methyl ethyl ketone can be further added and used. When coating on a drum, a dip coating method or the like is used.

[0029]

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

Example 1 1 part by weight of a bisazo pigment which is a pigment for an electrophotographic photoreceptor represented by the exemplified compound formula 1 and an epoxy resin (manufactured by Shin Nippon Rika;
1 part by weight of BPO-20E) was mixed with 100 parts by weight of methyl isobutyl ketone, and dispersed with soda glass beads (manufactured by Toshiba Barodyni; GB) having a diameter of 1 mm for 6 hours by a paint conditioner device. The average particle size of the pigment particles dispersed in this way is measured by a particle size distribution measuring device (CO
It was measured using ULTER; N4SD). here,
The average particle size is the center of gravity of the entire distribution from the minimum particle size to the maximum particle size. In addition, a pigment dispersion liquid is applied to a metal aluminum thin plate (JI
S standard # 1050) was applied with an applicator to form a film of a charge generating substance having a film thickness of 1 μm.

[0031]

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Next, 10 parts by weight of the hydrazone compound represented by the exemplified compound 2 and 10 parts by weight of a polycarbonate resin (manufactured by Teijin Chemicals; Panlite C-1400) are dissolved in 200 parts by weight of dichloromethane to prepare the above charge generating substance. This solution was applied onto the coating film by an applicator to form a charge transfer layer having a dry film thickness of 20 μm.

[0033]

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The laminated electrophotographic photosensitive member thus produced was attached to a drum-shaped aluminum tube, mounted on a commercial office copying machine, an image was formed, and it was investigated whether or not the image had a failure. The results are given in Table 1 together with the average particle size results.

Next, the electrophotographic photosensitive member was stored at room temperature in the dark for a whole day and night, and then the photosensitive member was charged with a voltage of -5.0 kV using an electrostatic recording tester (Kawaguchi Electric Co., Ltd .; SP-428). After being charged at 2, the half-exposure amount E1 / 2 of the photoconductor was measured by irradiating 2 lux of tungsten light. Separately, drum photoconductor evaluation device (Gentec; Cynthia 3
0), the potential after charging and the residual potential of the photoconductor were measured before and after 1000 times of repeating charging and discharging under the condition of room temperature of 23 ° C. and relative humidity of 55%. Table 2 shows the results.

Examples 2 and 3 Dispersion media were low-alkali beads (manufactured by Ohara Kogaku; Hibee D.20, diameter 1 mm) and yttria-containing zirconia beads (manufactured by Nikkato; YTZ, diameter 1 mm).
A pigment dispersion was prepared in the same manner as in Example 1, and an electrophotographic photosensitive member was prepared in the same manner as in Example 1 and tested. The results are shown in Tables 1 and 2.

Comparative Examples 1 to 3 Zircon beads (made by Sepul; zircon beads, diameter 1 mm) and alumina beads (made by Nikkato;
HD, diameter 1 mm), titania beads (Toyama Ceramic; titania beads, diameter 1 mm), a pigment dispersion liquid was prepared in the same manner as in Example 1, and an electrophotographic photoreceptor was prepared and tested in the same manner as in Example 1. It was The results are shown in Tables 1 and 2.

[0038]

[Table 1]

[0039]

[Table 2]

From the results shown in Table 1, when soda glass beads, low alkali glass beads, and yttria-containing zirconia beads were used for dispersion, the average particle size was far larger than that when zircon beads, alumina beads, and titania beads were used. It can be seen that it is extremely small and has good dispersibility. A pigment dispersion prepared using zircon beads, alumina beads, and titania beads causes sedimentation of pigment particles if left for 3 days, but soda glass beads, low alkali glass beads, and yttria-containing zirconia beads are used. The pigment dispersion thus prepared does not cause the pigment particles to settle even if it is allowed to stand for one week. Further, from the results of Table 1 and Table 2, the coating liquids produced by using soda glass beads, low alkali glass beads, and yttria-containing zirconia beads have good coating properties, and when these coating liquids are used, they are highly sensitive and repeatable. It can be seen that an electrophotographic photoreceptor having excellent characteristics and causing no image failure can be obtained. When zircon beads are used, the sensitivity and repeatability are not so bad, but the dispersibility is poor and the coatability is poor.

Example 4 Metal-free phthalocyanine (manufactured by Dainippon Ink; Fastogen Blue 812) which is a pigment for an electrophotographic photoreceptor.
0) 1 part by weight and 1 part by weight of a polyester resin (manufactured by Toyobo; Byron 220) are mixed with 100 parts by weight of cyclohexanone, and the diameter is 1 m by a paint conditioner device.
m soda glass beads (Toshiba Barodini; GB)
And dispersed for 6 hours. The average particle size of the pigment particles thus dispersed was measured in the same manner as in Example 1. Further, the pigment dispersion liquid was applied onto the metal aluminum thin plate used in Example 1,
The coating was performed by an applicator in the same manner as in Example 1 to form a film of the charge generating substance having a film thickness of 1 μm.

Next, 10 parts by weight of the stilbene compound represented by the exemplified compound 3 and 10 parts by weight of a polycarbonate resin (Z-200 manufactured by Mitsubishi Gas Chemical Co., Inc.) were added to dichloromethane 2
It was dissolved in 100 parts by weight, and this solution was applied onto the film of the above charge generating substance by an applicator to form a charge transfer layer having a dry film thickness of 20 μm. The same test as in Example 1 was conducted using the thus prepared photoconductor. The results are shown in Tables 3 and 4.

[0043]

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Examples 5 and 6 Dispersion media were low alkali glass beads (manufactured by Ohara Optical Co.
A pigment dispersion liquid was prepared in the same manner as in Example 4 as HiBe D · 20, diameter 1 mm) and yttria-containing zirconia beads (manufactured by Nikkato; YTZ, diameter 1 mm).
An electrophotographic photosensitive member was prepared and tested in the same manner as in. The results are shown in Tables 3 and 4.

Comparative Examples 4 to 6 Zircon beads (made by Sepul; zircon beads, diameter 1 mm) and alumina beads (made by Nikkato;
HD, diameter 1 mm), titania beads (Toyama Ceramic; titania beads, diameter 1 mm) were used to prepare a pigment dispersion liquid in the same manner as in Example 4, and an electrophotographic photosensitive member was prepared in the same manner as in Example 4 to perform a test. It was The results are shown in Tables 3 and 4.

[0046]

[Table 3]

[0047]

[Table 4]

From the results shown in Table 3, when soda glass beads, low alkali glass beads, and yttria-containing zirconia beads were used for dispersion, the average particle size was far larger than that when zircon beads, alumina beads, and titania beads were used. It can be seen that it is extremely small and has good dispersibility. A pigment dispersion prepared using zircon beads, alumina beads, and titania beads causes sedimentation of pigment particles if left for 3 days, but soda glass beads, low alkali glass beads, and yttria-containing zirconia beads are used. The pigment dispersion thus prepared does not cause the pigment particles to settle even if it is allowed to stand for one week. Further, from the results of Tables 3 and 4, the coating liquids produced using soda glass beads, low alkali glass beads, and yttria-containing zirconia beads have good dispersibility and coatability, and the use of these coating liquids produces high results. It can be seen that an electrophotographic photosensitive member is obtained which has excellent sensitivity and repeatability and does not cause image failure. When zircon beads are used, the sensitivity and repeatability are not so bad, but the dispersibility is poor and the coatability is poor.

Example 7 Alcohol-soluble nylon (Toray; CM-8000)
1 part by weight is dissolved in 100 parts by weight of methanol, 9 parts by weight of titanium oxide (rutile type, manufactured by Sakai Chemical Co., Ltd .; R-310) is mixed, and a diameter of 1 mm is obtained by a paint conditioner device.
Yttria-containing zirconia beads (made by Nikkato; Y
TZ) and dispersed for 5 hours. The titanium oxide dispersion thus obtained was applied to a thin aluminum metal plate (JIS standard # 10).
50), coated with an applicator to a film thickness of 0.5
An undercoat layer of μm was formed.

Next, 1 part by weight of a bisazo pigment, which is a pigment for an electrophotographic photosensitive member represented by the exemplified compound formula 4, and 1 part by weight of a phenoxy resin (manufactured by Union Carbide; PKHJ) are mixed with 100 parts by weight of dimethoxyethane. , And was dispersed for 6 hours together with soda glass beads (manufactured by Toshiba Barodyni; GB) having a diameter of 0.5 mm by a paint conditioner device. The average particle size of the pigment particles thus dispersed was measured in the same manner as in Example 1. Further, a film thickness of 1 was obtained by coating the above undercoat layer with an applicator in the same manner as in Example 1.
A μm film of charge generating material was formed.

[0051]

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Next, 10 parts by weight of the hydrazone compound represented by Exemplified Compound 5 and 10 parts by weight of polyarylate resin (U-Polymer manufactured by Unitika) were added to dichloroethane 200.
This solution was applied on a film of the above-mentioned charge generating substance by an applicator to give a dry film thickness of 20 μm.
m of charge transfer layers were formed. The same test as in Example 1 was conducted using the thus prepared photoconductor. The results are shown in Tables 5 and 6.

[0053]

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Examples 8 and 9 Dispersion media were low-alkali beads (Ohara Kogaku; Hibee D.20, diameter 0.5 mm), yttria-containing zirconia beads (Nikkato; YTZ, diameter 0.5 mm).
As a result, a pigment dispersion liquid was prepared in the same manner as in Example 7, and an electrophotographic photosensitive member was prepared in the same manner as in Example 7 and tested. The results are shown in Tables 5 and 6.

Comparative Examples 7 to 9 Dispersion media were zircon beads (made by Sepul; zircon beads, diameter 0.5 mm), alumina beads (made by Nikkato; HD, diameter 0.5 mm), titania beads (made by Toyama Ceramics; titania beads, With a diameter of 0.5 mm), a pigment dispersion liquid was prepared in the same manner as in Example 7, and an electrophotographic photosensitive member was prepared in the same manner as in Example 7 and tested. The results are shown in Tables 5 and 6.

[0056]

[Table 5]

[0057]

[Table 6]

From the results shown in Table 5, when soda glass beads, low alkali glass beads, and yttria-containing zirconia beads were used for dispersion, the average particle size was far larger than that when zircon beads, alumina beads, and titania beads were used. It can be seen that it is extremely small and has good dispersibility. A pigment dispersion prepared using zircon beads, alumina beads, and titania beads causes sedimentation of pigment particles if left for 3 days, but soda glass beads, low alkali glass beads, and yttria-containing zirconia beads are used. The pigment dispersion thus prepared does not cause the pigment particles to settle even if it is allowed to stand for one week. Further, from the results of Table 5 and Table 6, the coating liquid produced using soda glass beads, low alkali glass beads, and yttria-containing zirconia beads has good dispersibility and coatability, and the use of these coating liquids results in high dispersibility. It can be seen that an electrophotographic photosensitive member is obtained which has excellent sensitivity and repeatability and does not cause image failure. When zircon beads are used, the sensitivity and repeatability are not so bad, but the dispersibility is poor and the coatability is poor.

[0059]

As is apparent from the above, according to the present invention, a pigment dispersion having excellent coating properties and good stability, and an electrophotographic photosensitive member using the same, which has high sensitivity and excellent repetitive characteristics, can be provided. Can be provided.

Claims (2)

[Claims] 1. A method for producing a coating liquid for producing an electrophotographic photoreceptor, which comprises dispersing pigment particles for an electrophotographic photoreceptor together with a binder in a solvent, a dispersion medium for dispersing the pigment particles for an electrophotographic photoreceptor. Is soda glass beads,
A method for producing a coating liquid for producing an electrophotographic photoreceptor, which is at least one dispersion medium selected from low-alkali glass beads and yttria-containing zirconia beads. 2. An electrophotographic photosensitive member comprising a conductive support, and at least a charge generation layer and a charge transfer layer sequentially laminated on the conductive support, wherein the charge generation layer is a coating for producing an electrophotographic photosensitive member. An electrophotographic photosensitive member formed by using a liquid.