JPH0456964A - Production of dispersion of organic photoconductive azo pigment - Google Patents

Abstract

PURPOSE:To obtain the dispersion with which the flocculation state after dispersion hardly changes with lapse of time by processing is specific org. photoconductive azo pigment with a halogen solvent as a pre-stage for dispersion at the time of producing the solvent dispersion of the above-mentioned azo pigment. CONSTITUTION:The org. photoconductive azo pigment expressed by formula I is processed with the halogen solvent at the time of producing the solvent dispersion of the azo pigment as the pre-stage for dispersion. In the formula I, X denotes a hydrogen atom, halogen atom; A denotes a residual coupler group having a phenolic hydroxyl group and carbamoyl group. A charge generating layer 2 of a separated function electrophotographic sensitive body is formed by applying the dispersion directly on a conductive base 1 or on an under coating layer 5. This layer is also formable even by applying the dispersion on a charge transfer layer 3. The dispersion of the org. photoconductive material with which the flocculation state after dispersion hardly changes with lapse of time is obtd. in this way.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a dispersion of an organic photoconductive azo pigment suitable for electrophotographic photoreceptors. [Prior Art] Conventionally, as electrophotographic photoreceptors made of inorganic photoconductive materials, those containing selenium, cadmium sulfide, zinc oxide, etc. all over the surface 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 a low-molecular organic photoconductive substance such as diazole, and those using a combination of an organic photoconductive substance and various dyes and pigments are known. Electrophotographic photoreceptors using organic photoconductive substances have good film forming properties, can be produced by coating, and have extremely high productivity.
It has advantages such as low cost. or,
It has the advantage of being able to freely control color sensitivity by selecting the sensitizers used, such as dyes and pigments, and has been extensively studied. In particular, in recent years, functional separation has been developed in which a layer made of an organic photoconductive pigment is used as a charge generation layer, and a charge transport layer made of the aforementioned photoconductive polymer or low-molecular organic photoconductive substance is laminated on this to form a photoreceptor. The development of this technology has significantly improved the sensitivity and durability, which were considered to be shortcomings of conventional organic electrophotographic photoreceptors, and has facilitated their practical use. Furthermore, various pigments such as azo pigments that are suitable for functionally separated photoreceptors have already been discovered. It is known that the sensitivity and spectral characteristics of this type of electrophotographic photoreceptor are affected by the particle size and crystal form of the pigment, which is a charge generating substance. In the conventional method, a photoconductive composition (dispersion) is obtained by dispersing a pigment produced by a synthetic reaction in a solvent together with a binder using a ball mill, sand mill, attritor, etc. over a period of several hours to several tens of hours. has been done. However, with this method of directly dispersing pigments in a solvent, if the pigment is not kneaded sufficiently during dispersion, undispersed small lumps tend to remain in the dispersion, making it difficult to obtain a dispersion containing uniform particles. It was difficult. An electrophotographic photoreceptor manufactured using a photoconductive composition containing coarse particles of undispersed small agglomerates suffers from a decrease in carrier generation efficiency due to a decrease in covering power and a decrease in porosity due to the coarse particles. This increase causes a decrease in carrier mobility, and furthermore, the roughness of the surface of the charge generation layer is large, causing a deterioration in sensitivity such as a decrease in carrier injection efficiency into the charge transport layer. Furthermore, if the processing time for dispersed fine particles is increased, the number of coarse particles will certainly decrease, but the part of the particles that have already been finely dispersed will be overdispersed, resulting in a change in the agglomeration state.
During or after dispersion, the particle size tends to fluctuate, significantly impairing the stability of the dispersion. Furthermore, for pigments that undergo crystal transition in dispersion solvents,
Since the transition state of the crystal form fluctuates due to slight fluctuations in the dispersion conditions, the stability of the dispersion liquid over time may vary, and the sensitivity and spectral characteristic reproducibility of the produced electrophotographic photoreceptor may be poor. [Object of the Invention] An object of the present invention is to provide a method for producing a dispersion liquid that contains a finely divided organic photoconductive pigment with a stable crystalline state and whose agglomerated state after dispersion does not easily change over time. It is in. Another object of the present invention is to provide a method for producing a dispersion liquid that yields an electrophotographic photoreceptor that can exhibit high sensitivity and stable spectral sensitivity characteristics. (Structure of the present invention and its effects) The object of the present invention is to provide a method for producing a solvent dispersion of an organic photoconductive azo pigment represented by the following general formula [F], in which the azo pigment is added as a pre-dispersion step. This is achieved by a method for producing a dispersion of an organic photoconductive azo pigment, which is characterized by treatment with a halogenated solvent. It is represented by the general formula (F). In the general formula (F-1) ゝ・2-' , Ar represents a fluorinated hydrocarbon group or an aromatic carbocyclic group or an aromatic heterocyclic group having a substituent. Z forms a substituted or unsubstituted aromatic carbocycle or a substituted or unsubstituted aromatic heterocycle In particular, in the embodiment of the present invention, the fluorenone-based disazo pigment represented by the general formula [F] is represented by the following - ship stock [F1]
In the case of the pigment represented by , the effect of applying a halogenated solvent in the pre-dispersion step is significant. - Shipura CF,) In the formula, X represents a hydrogen atom or a halogen atom, A is a coupler residue having a phenolic hydroxyl group and a carbamoyl group, and in the following - Shipura (F-1), X in the formula It is effective that it is a halogen atom and at least one of R, -R, is a fluoroalkyl group. Specific examples of the fluorenone disazo pigment used in the present invention are listed below, but the present invention is not limited thereto. The fluorenone-based disazo pigment represented by -Funazo (p+) used in the present invention can be easily synthesized by a known method, for example, by the method disclosed in Japanese Patent Application No. 62-304862. Examples of halogenated solvents used in the pre-dispersion step of the present invention include ethylene chloride, methylene chloride, chloroform, carbon tetrachloride, ethylidene chloride (1,1 dichloroethane), Ii, J-) dichloroethane, 1゜1.1.2-tetra Examples include chloroethane, 1,2-dichloroethylene, and trichloroethylene, which can be used alone or in combination of two or more. The solvent treatment of the present invention can be carried out not only by directly contacting the synthesized organic photoconductive azo pigment with a solvent, but also by stirring the organic photoconductive azo pigment in the solvent, or by using a Soxhlet extraction apparatus. You can. Further, the pigment after the treatment may be in a wet state containing a solvent, or may be in a state in which the solvent has been dried by vacuum drying or the like. Among these, the state in which the pigment is dried is preferable. However, since the solvent after treatment contains impurities eluted from the pigment, it is preferable to remove the impurities together with the treatment solvent by means such as filtration in order to obtain a highly pure pigment. In the pre-process t, the pigment that has been pre-dispersed with a halogenated solvent as described above is then transferred to a dispersion process. As the binder resin, polyvinyl butyral, formal resin, polyamide, polyurethane, cellulose resin, polyester, polysulfone, styrene resin, polycarbonate, acrylic resin, etc. are used. or,
Specific dispersion methods include sand mill, colloid mill,
Methods such as an attritor ball mill can be used. In a functionally separated electrophotographic photoreceptor, a charge generation layer (CG
L) can be formed by coating the dispersion liquid directly on a conductive support or on an undercoat layer (marked as UCL). It can also be formed by coating it on the underlying charge transport layer (CTL). The film thickness of CGL is 5μm or less, especially 0.0! A thin film layer having a thickness of ~5 μm is desirable. This is because most of the incident light is absorbed by the CGL and many charge carriers are generated, and furthermore, the generated charge carriers need to be injected into the CTL without being deactivated by recombination or trapping. Furthermore, in the case of mass production, if the physical properties of the liquid vary greatly, it becomes difficult to form a uniform coating. Therefore, it is preferable that the flow characteristic is Newtonian fluidity. Coating can be performed using coating methods such as dip coating, spray coating, spinner coating, bead coating, wire bar coating, blade coating, roller coating, and curtain coating. For drying, it is preferable to perform preliminary drying at room temperature and then heat drying. Heat drying can be carried out at a temperature of 30'O to 200C for 5 minutes to 2 hours, either stationary or under ventilation. The CTL is electrically connected to the CGL and has the function of receiving and taking charge carriers injected from the CGL in the presence of an electric field and transporting these charge carriers to the surface. At this time, this CTL may be laminated on top of the CGL, or may be laminated below it. However, it is desirable that the CTL be stacked on top of the CGL. The material that transports charge carriers in the CTL; that is, the charge transport material (referred to as CTM) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the CGL is sensitive. The "electromagnetic waves" mentioned here include gamma rays, X-rays, ultraviolet rays,
Includes a broad definition of "light ray" that includes visible light, near-infrared rays, infrared rays, far-infrared rays, etc. When the photosensitive wavelength range of CTL matches or overlaps that of CGL, charge carriers generated in both trap each other, resulting in a decrease in sensitivity. CTL has electron-transporting substances and hole-transporting substances.
CTMs that can be used in the present invention include, for example, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives,
imidazole derivatives, imidacilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, amine derivatives, oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, These include aminostilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like. The CT&I used in the present invention has an excellent ability to transport holes generated during light irradiation to the support side, and
Those suitable for combination with the organic pigment used in the present invention are preferable, and such CTMs include the following - Funagura (
Examples include styryl compounds represented by T-A) and (T-B'), and distyryl compounds represented by (T-C). General formula (TA) In this formula, R++, R□ represent the following two substituted or unsubstituted groups; an alkyl group, an aryl group, and substituents include an alkyl group, an alkoxy group, and a substituted amino group. , hydroxyl group, halogen atom, and aryl group. Ars and Ar1 represent a substituted or unsubstituted aryl group, and examples of the substituent include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a norogen atom, and an aryl group. R13+ R14 is a substituted or unsubstituted aryl group,
It represents a hydrogen atom, and examples of the substituent include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a hydrogen atom, and an aryl group. The above-mentioned compound represented by Funazo (TA) is, for example, JP-A-58-65440, JP-A-5B-198425, JP-A-5
B-198043, No. 60-93445, No. 60-
No. 98437, etc. General formula (T-B) represents a group. The above compounds are described, for example, in JP-A-57-148750. General formula (T-C) rl Represents four groups: an alkyl group, a fused polycyclic hydrocarbon group, a heterocyclic group, and a fused polycyclic heterocyclic group. Three groups: fused polycyclic hydrocarbon group, heterocyclic group,
Represents a fused polycyclic heterocyclic group. In this formula, Rls is a substituted or unsubstituted aryl group, R11 is a hydrogen atom, a 710gen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an amino group, a substituted amino group, a hydroxyl group, and RIF is a substituted or unsubstituted Next post 2
Three groups: a fused polycyclic hydrocarbon group, a heterocyclic group, and a fused polycyclic heterocyclic group. Group, substituted or unsubstituted synopsis 4 groups; alkyl group,
It represents a fused polycyclic hydrocarbon group, a heterocyclic group, or a fused polycyclic heterocyclic group, and may also form a ring together with Ar and Ar. R3 is substituted or unsubstituted four groups; alkyl group, phenyl group, alkoxy group, phenoxy group, cyano group, halogen atom, carboxyl group, acyl group, hydroxyl group, nitro group, amino group, further substituted or unsubstituted six groups; alkylamino group, arylamino group, aralkylamino group, cyclic hydrocarbon group, three fused polycyclic carbon groups; fused polycyclic hydrocarbon group, heterocyclic group, fused polycyclic group Represents a cyclic heterocyclic group. R, R, and R6 are substituted or unsubstituted groups; alkyl group, phenyl group, alkoxy group, phenoxy group, and cyano group, halogen atom, carboxyl group, acyl group, hydroxyl group, nitro group , an amine group, and six substituted or unsubstituted groups: an alkylamino group, an arylamino group, an aralkylamino group, a cyclic hydrocarbon group, a fused polycyclic hydrocarbon group, and a heterocyclic group. Four substituted or unsubstituted groups; represent an alkyl group, a fused polycyclic hydrocarbon group, a heterocyclic group, and a fused polycyclic heterocyclic group, and may also form a ring with each other; They may join together to form a ring. R2 and R9 are substituted or unsubstituted groups;
Alkyl group, phenyl group, alkoxy group, phenoxy group, cyano group, halogen atom, carboxyl group, acyl group, hydroxyl group, nitro group, amino group, and four substituted or unsubstituted groups; alkylamino group, Represents a cyclic hydrocarbon group, a fused polycyclic hydrocarbon group, and a heterocyclic group. i, C, m, and n represent integers of θ to 5, and j represents an integer of 0 to 4. In addition, as CTM, the following general formula (T-D) or (T-E
) hydrazone compounds can also be used. -Formula (T-D) -In the ship, R1 and R8 are each a hydrogen atom or a halogen atom, R3゜ and R□ are each a substituted or unsubstituted aryl group, and Ar7 is a substituted or unsubstituted arylene. represents a group. The above compounds are described, for example, in JP-A-57-72148. In this stock, R3 is the following two groups, substituted or unsubstituted; aryl group, heterocyclic group; RSS is a hydrogen atom; R3 is the following two groups, substituted or unsubstituted; aralkyl group, aryl group, Q represents a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group, an alkoxy group, or a cyano group, and S is 0
or represents an integer of l. Moreover, pyrazoline compounds can also be used as CTM. Examples of the above compounds include JP-A-58-134642 and JP-A No. 58-134642;
No. 8-166354, etc. Other useful CTMs include, for example, JP-A-57-64
No. 244, No. 59-15252, No. 57-67940
No. 55-2285, No. 57-195254, No. 5G-4148, and the like. The following are examples of particularly useful CTMs. T-, 2 T-3 In addition to these organic CTMs, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used. Moreover, these CTMs are not limited to one type, but can be used in combination of two or more types. When CTM does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include insulating resins such as polyacrylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber; Mention may be made of organic photoconductive polymers such as poly-N-vinylcarbazole polyvinylpyrene. Since CTL has a limit in its ability to transport charge carriers,
It is not possible to make the film thicker than necessary. -Numerically, it is 5 to 30 μm, but the preferred range is 8
~20 μm. When forming the CTL by coating, an appropriate coating method as described above can be used. CGL like this! : A photosensitive layer consisting of a laminated structure of CTL is provided on a conductive support. As the conductive support, materials that have conductivity themselves, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, and platinum, can be used. In addition, aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. are coated by vacuum evaporation method, and conductive particles (e.g., carbon black, tin particles, etc.) are appropriately applied. A support coated on the metal or plastic with a binder, a support made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used. A UCL having a barrier function and an adhesive function can also be provided between the conductive support and the photosensitive layer. UCL consists of casein, polyvinyl alcoholose, ethylene-acrylic acid copolymer polyamide (
It can be formed from nylon 6, nylon 66, nylon 6101 copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of UCL is 0.01-5 μm, preferably 0.0
It is 3-3 μm. When using a photoreceptor in which a conductive support, CGL, and CTL are laminated in this order, and the CTM is made of an electron-transporting substance, the surface of the CTL must be positively charged, and when exposed after being charged, the CGL in the exposed area will be charged. The generated electrons are injected into the CTL, and then reach the surface and neutralize the positive charges, causing attenuation of the surface potential and creating 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., 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, and then visualized and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones. On the other hand, when the CTM is made of a hole-transporting substance, it is necessary to charge the charge-transporting surface negatively, and when exposed to light after charging, the holes generated in the CGL are injected into the CTL in the exposed area, and then reach the surface. Negative charges are neutralized, the surface potential is attenuated, and electrostatic contrast is created between the surface potential and the unexposed area. 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 containing the photoconductive organic azo pigment and CTM in the same layer. At this time, in addition to the CTM described above, a charge transfer complex compound consisting of poly-N-vinylcarbazole and trinitrofluorenone can be used. 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. Each photoreceptor contains at least one type of pigment, and if necessary, pigments with different light absorptions may be used in combination to increase the sensitivity of the photoreceptor or to obtain a panchromatic photoreceptor. It is also possible to use more than one species. The electrophotographic photoreceptor prepared from the pigment dispersion of the present invention can be used not only for electrophotographic copying machines, but also for laser printers, C
It can also be widely used in electrophotographic applications such as RT printers. Examples of the organic pigment dispersion medium and binder resin solvent used in the present invention include hexane, benzene, toluene,
Hydrocarbons such as xylene, methylene chloride, methylene bromide, 1,2-dichloroethane, sym-tetrachloroethane, cis-1,2-dichloroethylene,
1.1.2-trichloroethane, 1.1゜1) dichloroethane, 1.2-dichloropropane, chloroform,
Halogenated hydrocarbons such as bromoform and chlorobenzene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate,
methanol, ethanol, propatool, butanol,
Alcohols and their derivatives such as cyclohexanol, heptatool, ethylene glycol, methyl cellosolve, ethyl cellosolve, and acetic cellosolve, ethers such as tetrahydrofuran, '1,4-dioxane, furan, and furfural, acetals, pyridine, butylamine, diethylamine, and ethylenediamine. , amines such as isopropanolamine, amides such as N,N-dimethylformamide, fatty acids and phenols,
Examples include sulfur and phosphorus compounds such as carbon disulfide and triethyl phosphate. In the present invention, the photosensitive layer may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use. Examples of electron-accepting substances that can be used here include succinic anhydride, maleic anhydride, dibromaleic anhydride, 7-talic anhydride, tetrachlorophthalic anhydride, tetrabrom-7-thalic anhydride, 3-nitro 7-tallic anhydride. acid, 4
-Nitro-7tallic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, -1-dinitrobenzene,
1.3.5-trinitrobenzene, paranitrobenzonitrile, vicryl chloride, quinone chlorimide, chloranil, brumanil, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, 2.
7-cyclohexanone, 2.4.7-trinitrofluorenone, 2.4.5.7-tetranitrofluorenone, 9-fluorenylidene

[dicyanomethylenemalonodinitrile 1, polynitro-9-fluorenylidene-[dicyanomethylenemalonodinitrile], picric acid, 0-
Nitrobenzoic acid, p-nitrobenzoic acid, 3.5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3.5-dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds with high electron affinity are listed. be able to. In addition, the addition ratio of the electron-accepting substance is as follows: organic pigment used in the present invention:electron-accepting substance-1
oo: 0.01-200, preferably 100:
It is 0.1-100. The proportion of electron-accepting substances added to such a layer is based on the weight ratio of total C.
TM: Electron accepting substance = 100: 0.01-1
00, preferably too:o, t~50. Further, organic amines can be added to the photosensitive layer of the present invention for the purpose of improving the charge generation function of CGM, and in particular, 2
Preferably, a grade amine is added. These compounds are described in JP-A-59-218447 and JP-A-62.
-8160. Furthermore, an antioxidant can be added to the photosensitive layer I of the present invention for the purpose of preventing ozone deterioration. Typical examples of such antioxidants are shown below, but the invention is not limited thereto. 1-group; hindered phenols, n-group; heterophenylenediamines, m-p; hydroquinones, ■-group;
Organic sulfur compounds, group ①; include organic phosphorus compounds. These compounds are disclosed, for example, in JP-A-63-18354. These compounds are known as antioxidants for rubber, plastics, oils and fats, and are easily available commercially. The amount of antioxidant added is 0.00 parts by weight per 100 parts by weight of CTM.
1-100 parts by weight, preferably 1-50 parts by weight, particularly preferably 5-25 parts by weight. In addition, the photoreceptor of the present invention may also contain, if necessary, an ultraviolet absorber or the like for the purpose of protecting the photosensitive layer, or may contain a dye for color sensitivity correction. Further, the protective layer according to the present invention may contain less than 5 Qvt% of a thermoplastic resin, if necessary, for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). In addition, the intermediate layer functions as an adhesive layer or a blocking layer, and in addition to the binder resin, it may contain, for example, vinyl alcohol, ethyl cellulose, carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate. -Maleic anhydride copolymer, casein, N-alkoxymethylated nylon, starch, etc. are used. As shown in FIGS. 1 and 2, the photoreceptor of the present invention comprises CCl2 containing CGM as a main component and CTM on a conductive support l.
A photosensitive layer 4 made of a laminate with CTL 3 containing CTL 3 as a main component is provided. As shown in FIGS. 3 and 4, this photosensitive layer 4 may be provided via a UCL 5 provided on a conductive support l. When the photosensitive layer 4 has a two-layer structure in this manner, an electrophotographic photoreceptor having the best electrophotographic properties can be obtained. In addition, in the present invention, FIGS. 5 and 6
As shown in the figure, a photosensitive layer 4 formed by dispersing fine particulate CGM 7 in a layer 6 mainly composed of CTM may be provided on the conductive support 1 directly or via a UCL 5. Furthermore, a protective layer 8 may be provided on the photosensitive layer 4 if necessary. Here, when the photosensitive layer 4 has a two-layer structure, CCl2 and CT
Which of L3 is to be used as the upper layer is determined depending on whether the charging polarity is positive or negative. That is, when forming a negatively charged photosensitive layer, it is advantageous to use CTL 3 as an upper layer, because CTM in CTL 3 is a substance that has a high transport ability for holes. Further, CCl2 constituting the photosensitive layer 4 having a two-layer structure can be formed directly on the conductive support l or CTL3 or after providing an intermediate layer such as an adhesive layer or a blocking layer as necessary. can. The thickness of CCl2 thus formed is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm, as described above. On the other hand, the thickness of the CTL 3 can be changed as needed, but it is usually preferably 5 to 30 μm. The composition ratio in this CTL 3 is preferably 0.1 to 5 parts by weight of the binder to 1 part by weight of the CTM of the present invention, but when forming the photosensitive layer 4 in which fine particulate CGM is dispersed, C011 It is preferable to use the binder in an amount of 5 parts by weight or less based on the weight part. Further, when the CGL is configured as a dispersed type in a binder, it is preferable to use the binder in an amount of 5 parts by weight or less per 1 part by weight of the CGM. [Examples] Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited thereto. Example 1 Weighed 20 g of the disazo pigment of Example F-7, transferred it to a Nutsche covered with cloth, and added 500 m of methylene chloride.
12 was poured evenly. This operation was repeated four times. Thereafter, it was dried day and night in a vacuum dryer at 100°C to obtain 19.5 g of solid pigment. On the other hand, on an aluminum vapor-deposited base, 30 g of polyamide resin Diaamide
) A solution dissolved in 3000+++12 was applied with a wire bar and air-dried to form a UCL with a thickness of 0.3 μI. Next, 12.5 g of the previously obtained solid pigment was put into a sand grinder using glass beads together with a binder liquid (5 g of binder resin S-LEC BX-1 (Sekisui Chemical Co., Ltd.)/630 mff of methyl ethyl ketone), and dispersed for 4 hours. . Apply the obtained dispersion onto the above UCL with a wire bar,
A CGL with a thickness of 0.8 μm was formed. Next, 150 g of a Nobi-7 enyl stilbene compound with the following structural formula and polycarbonate resin Kneepilon Z-20 were added.
0 (Mitsubishi Gas Chemical Co., Ltd.) was dissolved in 1000 m+2 of 1,2-dichloroethane, applied onto the above CGL using a doctor blade, dried at 90°C for 60 minutes, and a thickness of 2.
CTLs of 0 μm were formed. The electrophotographic photoreceptor thus obtained is designated as sample 1. Example 2 Example 1 except that the disazo pigment of Example F-6 was replaced.
An electrophotographic photoreceptor was produced in exactly the same manner as described above. This is designated as sample 2. Example 3 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 1 except that the processing method was changed as follows. This is designated as sample 3. 20 g of the disazo pigment used in Example 1 was weighed and loaded into a Soxhlet extraction device. The extraction solvent was methylene chloride. After this extraction was carried out for 6 hours, it was taken out from the apparatus and dried in a 1OO'O vacuum dryer, day and night, to obtain 18.8 g of solid pigment. Example 4 An electrophotographic photoreceptor was produced in exactly the same manner as in Example I except that the pigment in Example 1 was replaced with the disazo pigment of Example F-9. This is designated as sample 4. Comparative Example 1 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 1, except that the methylene chloride treatment was not performed. This is designated as comparative sample 1. Comparative Example 2 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 2, except that the methylene chloride treatment was not performed. This will be referred to as comparative sample 2. Comparative Example 3 An electrophotographic photoreceptor was produced in exactly the same manner as in Example 3, except that methyl ethyl ketone was used as the treatment solvent in the pre-dispersion step. This will be referred to as comparative sample 3. Each electrophotographic photoreceptor produced as described above was then subjected to an electrostatic charging tester (EPA-8100; manufactured by Kawaguchi Electric Co., Ltd.) to be corona charged to -6 kV in a dynamic range.
Expose to light at an illuminance of 8 Qux and examine the potential characteristics. As for the charging characteristics, the surface potential (Va) and the exposure amount (E@0°) required to attenuate the charge from 600 cm to 1 oov were measured. Furthermore, the disazo pigment dispersion liquid obtained when each electrophotographic photoreceptor was prepared was stored statically at room temperature in a sealed state for 60 days, and the pigment dispersion particle diameter (Di.) was measured using a laser rotation type particle size distribution measuring device (
Measured with Microtrac MK-I+ (Nikkiso Co., Ltd.). In addition, the fluidity characteristics of the dispersions were measured using Rotovisco MV-20 (Haake), and the fluidity was compared. The above results are shown in Table 1. Regarding the fluidity of the dispersion, if the liquid properties are Newtonian fluid, the 70-curve defined between the shear rate and shear stress 1 gives a straight line passing through the origin and having an inclination of angle σ, Furthermore, the viscosity curve l obtained from the straight line
+7wtani”τ without depending on shear speed
/D is given. Therefore, if the dispersion liquid is a Newtonian fluid, the pot life of the dispersion liquid will be long during the production of photoreceptor drums, and the physical properties of the liquid will not change, allowing uniform coating for a long period of time. On the other hand, if the adsorption of the binder to the pigment in the dispersion liquid is insufficient and a non-Newtonian fluid is provided, the pigment will aggregate and lose uniform dispersibility, and as the coating progresses, the viscosity will thicken (change and become less reproducible). A certain uniform coating surface It is possible to provide a dispersion liquid of 100%, and uniform coating is possible even during mass production.In addition, the sensitivity does not change even when treated with a halogenated solvent, and the electrophotographic photoreceptor can exhibit high sensitivity characteristics. Obtainable.

[Brief explanation of drawings]

1 to 6 are cross-sectional views of the photoreceptor according to the present invention. l... Conductive support 2... Charge generation layer (L to C) 3...Charge transport layer (CTL) 4...Photosensitive layer 5... Undercoating layer (UCL) 6...Single layer photosensitive layer ? ...Charge generating material (CGM)

Claims (1)

[Claims] A method for producing a solvent dispersion of an organic photoconductive azo pigment represented by the following general formula [F], characterized in that the azo pigment is treated with a halogen-based solvent as a pre-dispersion step. A method for producing a dispersion of an organic photoconductive azo pigment. General Formula [F] ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [In the formula, X represents a hydrogen atom or a halogen atom, and A represents a coupler residue having a phenolic hydroxyl group and a carbamoyl group. ]