JPH0473873B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a method for manufacturing an electrophotographic photoreceptor comprising a photoconductive layer composition. [Prior Art] Conventionally, as electrophotographic photoreceptors made of inorganic photoconductive substances, those using selenium, cadmium sulfide, zinc oxide, etc. have been widely used. On the other hand, electrophotographic photoreceptors made of organic photoconductive substances include photoconductive polymers typified by poly-N-vinylcarbazole and 2,5-bis(P-diethylaminophenyl)-1,3,4-oxa Those using low-molecular organic photoconductive substances such as diazole, and furthermore, those in which such organic photoconductive substances are combined with various dyes and pigments are known. An electrophotographic photoreceptor using an organic photoconductive substance has good film forming properties, can be produced by coating, has extremely high productivity, and has the advantage of being able to provide an inexpensive photoreceptor. Further, it has the advantage that color sensitivity can be freely controlled by selecting the sensitizer such as dye or pigment to be used, and a wide range of studies have been carried out to date. In particular, recently, with the development of a functionally separated photoreceptor in which an organic photoconductive pigment is used as a charge generation layer and a so-called charge transport layer made of the aforementioned photoconductive polymer or a low-molecular organic photoconductive substance is laminated, Significant improvements have been made in the sensitivity and durability, which were considered to be drawbacks of conventional organic electrophotographic photoreceptors, and they have come into practical use. Furthermore, various compounds and pigments that are suitable for functionally separated photoreceptors have also been discovered. On the other hand, such a functionally separated photoreceptor is composed of at least two layers, a charge generation layer and a charge transport layer, so charge carriers generated by light absorption in the charge generation layer are injected into the charge transport layer, and the photoreceptor is This causes the surface charge to disappear and creates an electrostatic contrast. The sensitivity of this type of photoreceptor is affected by the particle size of the charge-generating substance contained in the charge-generating layer, and generally uses a charge-generating substance with a particle size of about 1μ or less, preferably 0.5μ or less. It is considered desirable in terms of sensitivity when For this reason, in conventional manufacturing methods, after refining the pigment or dye obtained through a synthetic reaction, the powder is heated and dried for several hours together with a binder using a sand mill, pole mill, or attritor. A method is adopted in which the particles are micronized to about 1 μm or less, preferably in the form of fine particles. However, the particle size of particles obtained by such conventional methods fluctuates according to changes in temperature and humidity during the process, and coarse particles are likely to form especially when heated to a temperature of 50°C or higher. Therefore, it is necessary to sufficiently crush the pigment, but in practice, the number of coarse particles must be sufficiently reduced through the crushing process, and
Obtaining fine particle compositions with reduced agglomeration and thixotropy involves technical difficulties. Moreover, since the state of agglomeration of particles changes depending on the manufacturing environment, it is not possible to carry out atomization treatment under certain conditions, which is a bottleneck in manufacturing. In addition, because it contains a large amount of coarse particles,
This electrophotographic photoreceptor not only suffers from a decrease in the number of carriers generated due to a decrease in hiding power, but also a decrease in carrier mobility due to an increase in porosity due to coarse particles. It has many drawbacks in terms of sensitivity, such as a decrease in the efficiency of carrier injection into the transport layer, and also has drawbacks, such as poor potential stability during long-term use. Furthermore, coating liquids containing fine particulate organic pigments and dyes have problems with liquid stability, and have drawbacks such as increased agglomeration and thixotropy, leading to a decrease in productivity. . [Object of the Invention] Accordingly, an object of the present invention is to provide a method for manufacturing an electrophotographic photoreceptor comprising a photoconductive layer composition containing a particulate organic pigment or dye. Another object of the present invention is to provide a method for manufacturing an electrophotographic photoreceptor comprising a photoconductive layer composition that can sufficiently reduce the generation of coarse particles. Another object of the present invention is to provide a method for producing a photoconductive composition that can form an electrophotographic photoreceptor having high sensitivity characteristics and stable potential characteristics during long-term use. Furthermore, another object of the present invention is to provide a method for producing an electrophotographic photoreceptor comprising a photoconductive layer composition containing a photoconductive organic pigment or dye in the form of particulates and whose coating solution is stable. There is a particular thing. The above purpose is to place an organic pigment or dye powder obtained by a synthesis reaction under reduced pressure, and then, when returning to normal pressure, contact it with an inert gas so that the powder adsorbs the inert gas, and then This is achieved by dispersing the powder in a binder to form a photoconductive composition, and forming a film from the photoconductive composition. Examples of the organic pigments used in the present invention include azo pigments, phthalocyanine pigments, quinacridone pigments, cyanine pigments, hyrylium pigments, thiahyrylium pigments, indigo pigments, scaric acid pigments, and polycyclic quinone pigments. Examples of the dyes include pyrylium dyes, thiapyrylium dyes, triarylmethane dyes, thiazine dyes, and cyanine dyes. It can be used as a charge generating material for electrophotographic photoreceptors. For example, when discussing the synthesis reaction of disazo pigments, first, 2,5-bis(P-aminophenyl)-1,3,4-oxadiazole, 3,3'-
A diamine such as dichlorobenzidine, diaminostilbene, or diaminodistilbene is tetrazotized by a conventional method, and then a coupler is subjected to an azo coupling reaction in the presence of an alkali, or the tetrazonium salt of the diamine is converted to a borofluoride salt or a zinc chloride double salt. After separation, a disazo pigment can be synthesized by carrying out an azo coupling reaction with a coupler in an appropriate solvent in the presence of an alkali. Then, after washing with water, dimethylformamide (DMF), dimethylacetamide (DMAC), methanol, ethanol, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), benzene, xylene, toluene, tetrahydrofuran (THF) It can be purified by washing with solvents such as The thus purified synthetic organic pigment is dispersed in a solvent during purification or in a paste state, and then dried using various methods to provide the present invention in a powder state. be placed. Further, the reduced pressure state itself may be part of the drying process. The dried pigment powder is preferably finely divided to about 200μ or less, preferably about 100μ or less. The water or organic solvent or adsorbed air is almost completely degassed under reduced pressure, preferably 1
After the degree of vacuum has stabilized below mmHg, inert gas,
Preferably, the pressure is returned to normal while bringing nitrogen gas or the like into contact, thereby obtaining a dry pigment powder with an inert gas adsorbed thereon. In this way, the pigment powder to which an inert gas has been adsorbed according to the present invention is dispersed and formed into a film according to the following procedure to form a photoconductive composition, which is used to form an electrophotographic photoreceptor. . First, pigment powder is prepared using methanol, ethanol,
Alcohol solvents such as IPA, acetone, MEK,
Ketone solvents such as MIBK, cyclohexanone,
A dispersion can be made by adding only the pigment or a binder resin to various solvents such as aromatic solvents such as benzene, toluene, xylene, and chlorobenzene, and DMF and DMAC. As the dispersion means, methods such as a sand mill, colloid mill, attritor, and ball mill can be used. Binder resins include polyvinyl butyral, formal resin, polyamide resin, polyurethane resin, cellulose resin, polyester resin,
Polysulfone resin, styrene resin, polycarbonate resin, acrylic resin, etc. are used. In the method of the present invention, the dried pigment is brittle and therefore can be easily turned into a fine particle dispersion of 1 μm or less by simple dispersion treatment, and is extremely stable without any increase in cohesiveness. When this is used as an electrophotographic photoreceptor, improvements are seen in the sensitivity characteristics and the charge characteristics during use, as is clear from the examples below. Furthermore, in the method of the present invention, a photoconductive composition can be prepared in the same manner using pigments or dyes other than the above-mentioned disazo pigments. In the method of the present invention, when a charge generating layer is formed using a photoconductive composition, the above-mentioned dispersion is applied directly onto a conductive support or onto an adhesive layer. It can also be formed by coating on the charge transport layer described below. The thickness of the charge generation layer is desirably a thin layer having a thickness of 5 microns or less, preferably 0.01 to 1 micron. Most of the incident light is absorbed by the charge generation layer to generate many charge carriers, and the generated charge carriers must be injected into the charge transport layer without being deactivated by recombination or trapping. , it is preferable to set the film thickness as described above. Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to dry to the touch at room temperature and then heat dry.
Heat drying can be carried out at a temperature of 30° C. to 200° C. for 5 minutes to 2 hours, either stationary or with ventilation. In an electrophotographic photoreceptor, the charge transport layer is electrically connected to the charge generation layer described above, receives charge carriers injected from the charge generation layer in the presence of an electric field, and transports these charge carriers to the surface. It has the ability to be transported. At this time, this charge transport layer may be laminated on or under the charge generation layer.
However, it is desirable that the charge transport layer is laminated on the charge generation layer. Since the photoconductor generally has the function of transporting charge carriers, the charge transport layer can be formed by the photoconductor. The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive. The term "electromagnetic waves" used herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both trap each other, resulting in a decrease in sensitivity. Charge transport substances include electron transport substances and hole transport substances, and electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2,4,7-trinitro-9-fluorenone. , 2, 4, 5, 7-
Tetranitro-9-fluorenone, 2,4,7-
trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone,
Examples include electron-withdrawing substances such as 2,4,8-trinitrothioxanthone, and polymerized versions of these electron-withdrawing substances. Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
N-Methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-
3-methylidene-10-ethylphenothiazine,
N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, P-diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N
-α-naphthyl-N-phenylhydrazone, P-
Pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone hydrazones such as 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1
-Phenyl-3-(P-diethylaminostyryl)
-5-(P-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]- 3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[6-methoxy-pyridyl(2)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1- [Pyridyl(3)]-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[Lepidyl(2)]-3-(P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-
3-(P-diethylaminostyryl)-4-methyl-5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-P-
diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(P-diethylaminostyryl)-4-methyl-5
-(P-diethylaminophenyl)pyrazoline,
1-Phenyl-3-(α-benzyl-P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(P-diethylaminostyryl)
-6-diethylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl)-4-(P-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2
-(P-diethylaminostiri)-6-diethylaminobenzothiazole and other thiazole compounds,
Triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N-diethylamino-2-methylphenyl)heptane, 1,1,
Polyarylalkanes such as 2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-
Examples include vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, and ethylcarbazole formaldehyde resin. In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used. Moreover, these charge transport substances may be one or two types.
More than one species can be used in combination. When the charge transport material does not have film-forming properties,
A film can be formed by selecting an appropriate binder. Resins that can be used as binders are:
For example, insulating resins such as acrylic resin polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or poly-N-vinyl Mention may be made of organic photoconductive polymers such as carbazole, polyvinylanthracene, polyvinylpyrene. Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Typically it is between 5 microns and 30 microns, with a preferred range between 8 microns and 20 microns. When forming the charge transport layer by coating, an appropriate coating method as described above can be used. A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer. As the substrate having a conductive layer, materials that are themselves conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum. Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, , acrylic resin, polyethylene fluoride, etc.), conductive particles (e.g. carbon black,
A substrate made of plastic coated with silver particles (silver particles, etc.) together with a suitable binder, a substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 6,6, nylon 6,10, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, oxidized It can be formed from aluminum or the like. The thickness of the undercoat layer is 0.1 micron to 5 micron.
Preferably, 0.3 micron to 3 micron is appropriate. When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones. On the other hand, when the charge transport material consists of a hole transport material, the surface of the charge transport layer must be negatively charged.
After charging, when exposed to light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, causing a decrease in the surface potential and static electricity between the exposed area and the unexposed area. Electrocontrast occurs. During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used. Another specific example of the present invention is an electrophotographic photoreceptor in which the photoconductive organic pigment described above is contained in the same layer as a charge transport material. At this time, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used in addition to the above-mentioned charge transport substance. The electrophotographic photoreceptor of this example can be prepared by dispersing the aforementioned organic photoconductor and charge transfer complex compound in a polyester solution dissolved in tetrahydrofuran, and then forming a film thereon. All photoreceptors contain at least one type of pigment, and if necessary, pigments can be added to increase the sensitivity of the photoreceptor by combining pigments with different light absorption, or to obtain a panchromatic photoreceptor. It is also possible to use two or more types. The electrophotographic photoreceptor using the photoconductive composition obtained by the method of the present invention can be used not only in electrophotographic copying machines but also in a wide range of electrophotographic applications such as laser printers and CRT printers. . Hereinafter, the present invention will be explained according to examples. Example 1 In a 500ml beaker, add 80ml of water and 16.6ml of concentrated hydrochloric acid (0.19ml).
mole) 6.53 g (0.029 mol) of the diamine represented by was added and stirred while cooling in an ice water bath to bring the temperature of the solution to 3°C. Next, add 4.2 g (0.061 mol) of sodium nitrite to 7 ml of water.
ml of the solution was added dropwise over 10 minutes while controlling the temperature within the range of 3 to 10°C, and after the completion of the addition, the solution was stirred for an additional 30 minutes at the same temperature. After the reaction, carbon was added and filtered to obtain a tetrazotized solution. Next, put 700ml of water into 2 beakers and dissolve 21g (0.53mol) of caustic soda, then naphthol AS.
(3-hydroxy-2-naphthoic acid anilide)
16.2 g (0.061 mol) was added and dissolved. Cool this coupler solution to 6℃ and reduce the liquid temperature to 6-10℃.
Add the above-mentioned tetrazotization solution while controlling the temperature at
The mixture was added dropwise over 30 minutes with stirring, and then stirred at room temperature for 2 hours and further left overnight. After filtering the reaction solution, it was washed with water to obtain 19.08 g of a crude pigment. Next, each 400ml of N,
Washing was repeated five times with N-dimethylformamide. Thereafter, washing was repeated three times with 500 ml each of MEK to obtain 67.32 g of MEK paste of purified pigment.
Pigment solid content in MEK paste is 25% and yield is 75%
It was hot. Moreover, the obtained pigment has the following structure. Next, the powder obtained by heating and drying 20 g of the purified pigment MEK paste at a temperature of 60 ° C. for 4 hours is crushed using an agate mortar, sieved, and the powder of 74 μ or less is placed in a vacuum dryer. 12 at vacuum level 0.05~0.07Torr
After drying under reduced pressure for an hour, dry nitrogen gas was introduced to return the pressure to normal pressure, yielding 4.69 g of nitrogen-adsorbing pigment powder. Next, the above dry powder pigment was added to a solution prepared by dissolving 2 g of butyral resin (degree of butyralization: 63 mol %) in 95 ml of MEK, and dispersed with an attritor for 2 hours. Next, place an ammonia solution of casein on an aluminum plate (casein 11.2 g, 28% ammonia water 1 g, water
222 ml) was applied using a Mayer bar so that the film thickness after drying was 1.0 micron, and dried. The previously dispersed pigment dispersion was applied onto this casein layer using a Mayer bar so that the film thickness after drying was 0.5 microns.
It was dried to form a charge generation layer. Next, 5 g of P-diethylaminobenzaldehyde-N,N-diphenylhydrazone and 5 g of polymethyl methacrylate resin (number average molecular weight 100,000) were added.
g was dissolved in 70 ml of benzene, and applied onto the charge generation layer using a Mayer bar so that the film thickness after drying was 12 microns, and dried to form a charge transport layer. On the other hand, for comparison, a comparative sample 1 corresponding to sample 1 was prepared using a powder pigment obtained by returning the pigment to normal pressure without adsorbing nitrogen gas. The electrophotographic photoreceptor prepared in this way was used with electrostatic copying paper manufactured by Kawaguchi Electric Co., Ltd. and a test device "Model sp-428".
The sample was statically charged with a corona at -5kV using a 1000V, held in a dark place for 1 second, and then exposed to light at an illuminance of 5lux to examine its charging characteristics. As for the charging characteristics, the surface potential V _D and the exposure amount E 1/2 required to attenuate the potential by 1/2 when dark decaying for 1 second were measured. The results are shown in Table 1. Table 1 V _D (-V) E1/2 (lux・sec) Sample 1 595 4.2 Comparative sample 1 580 8.4 Furthermore, in order to measure the fluctuations in the bright area potential and dark area potential during repeated use, this example The photoreceptor made with -5.6kV corona charger, exposure amount
12lux・sec exposure optical system, developer, transfer charger,
It was attached to the cylinder of an electrophotographic copying machine equipped with a static elimination exposure optical system and a cleaner. This copying machine is configured to produce an image on transfer paper as a cylinder is driven. Using this copying machine, the initial bright area potential V _L and dark area potential V _D and 5000
The light area potential V _L and dark area potential V _D were measured after each use. The results are shown in Table 2.

[Table] From the results in Tables 1 and 2, the photoreceptor manufactured by the manufacturing method of the present invention has a high sensitivity and V _D ,
It can be seen that the stability of _VL is also extremely excellent. Example 2 Phthalic anhydride 148g, urea 180g, anhydrous chloride 1
25 g of copper, 0.3 g of ammonium molybdate, and 370 g of benzoic acid were reacted at 190° C. for 3.5 hours with stirring. After the reaction was completed, benzoic acid was distilled under reduced pressure, followed by washing with water, washing with acid, and washing with water in order to obtain 130 g of crude copper phthalocyanine. This crude phthalocyanine was dissolved in 1,300 g of concentrated sulfuric acid, stirred at room temperature for 2 hours, poured into a large amount of ice water, and the precipitated pigment was separated and washed with water until it became neutral. Next, the mixture was stirred and filtered six times with DMF 2.6, and then twice with water 2.6 to obtain 467 g (solid content: 27%, 126 g) of a water paste of purified copper phthalocyanine. Next, 20 g of the water paste of the purified pigment was applied to the inner walls of four 200 ml eggplant-shaped flasks, and the flasks were immersed in liquid nitrogen to pre-freeze, followed by freeze-vacuum drying. The freeze-vacuum dryer used was Neo Cool Freeze Dryer DC-55A manufactured by Yamato Scientific Co., Ltd. After freeze drying for 18 hours at a vacuum degree of 0.02 to 0.06 Torr, nitrogen gas was introduced to return the pressure to normal pressure, and 5.02 g of a bulky solid adsorbed with nitrogen was obtained. Next, cellulose acetate butyrate resin 2
The dried pigment was added to a solution prepared by dissolving 1.g of the pigment in a mixed solvent of 95 ml of MEK and 15 ml of cyclohexane, and dispersed in a ball mill for 40 hours. The above pigment dispersion was applied in the same manner as in Example 1 onto the PVA layer of an aluminum plate provided with a polyvinyl alcohol (PVA) layer with a thickness of 1μ,
It was dried to form a charge generation layer with a thickness of 0.2μ. Next, 5 g of 1-(2-pyridyl)3-P-diethylaminostyryl-5-P-diethylaminophenylpyrazoline and poly-4,4'-dioxydiphenyl-2,2-propane carbonate (molecular weight
30000) dissolved in 70ml of THF was applied onto the charge generation layer using a Mayer bar and dried to give a density of 10g/ ^m2.
A charge transport layer was formed. (Sample 2). On the other hand, a comparative sample 2 was prepared corresponding to sample 2 using a powder pigment obtained by returning the water and paste of the pigment used in sample 2 to normal pressure without bubbling with nitrogen. The charging characteristics and durability of the electrophotographic photoreceptor thus prepared were tested in exactly the same manner as in Example 1, and the results are shown in Tables 3 and 4. (However, the exposure amount during the durability test was 15lux・sec). Table 3 V _D (-V) E1/2 (lux・sec) Sample 2 560 5.6 Comparative sample 2 575 9.2

[Table] From the results in Tables 3 and 4, it can be seen that, similar to Example 1, the photoreceptor manufactured by the manufacturing method of the present invention has extremely excellent characteristics. Furthermore, the above-mentioned Example 1, Example 2, Comparative Example 1,
The stability of the dispersion coating liquid used in Comparative Example 2 was evaluated as follows.
It was tested using the method described in Section 1. (1) Leave the bottle tightly closed (Pour the dispersion coating liquid into the sample bottle,
(2) Open stirring (Pour the dispersion coating liquid into the sample bottle,
Stir with a stirrer and leave to stand without a stopper. (3) Using a circulation coating system model (attached drawing) consisting of a circulation tank, liquid reservoir, pump, pressure gauge, and filter, continuous operation was performed at a liquid flow rate of 400ml/min.Evaluation method: , (1), (2), and (3), an aluminum sheet is immersed in the dispersion liquid and pulled up, and the cohesiveness is determined by whether granular deposits are observed on the dried film. Regarding this, the stability of the dispersion liquid is judged by whether the filter is clogged and the pressure gauge rises. It was determined that the dispersion coating liquid with no increase in pressure gauge had good stability. The results are shown in the table below.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a photoconductive composition composed of a fine particulate organic pigment or dye that does not contain coarse particles, and when this is used as a coating solution for an electrophotographic photoreceptor, fine particles can be obtained. A coating liquid having excellent dispersion stability can be obtained, and an electrophotographic photoreceptor having high sensitivity characteristics and stable potential characteristics during long-term use can be formed.

[Brief explanation of drawings]

The drawing is a conceptual diagram of the circulating coating system model used in the "Example". 1...Circulation tank, 2...Liquid reservoir, 3...Pump,
4...Pressure gauge, 5...Filter.

Claims (1)

[Claims] 1. The organic pigment or dye powder obtained by the synthesis reaction is placed under reduced pressure, and then, when returning to normal pressure, it is brought into contact with an inert gas to cause the powder to adsorb the inert gas, and then the powder is 1. A method for producing an electrophotographic photoreceptor, which comprises dispersing in a binder to form a photoconductive composition, and forming a film from the photoconductive composition.