JPS6113255A - Preparation of organic photoconductor and charge generating material made of it - Google Patents

Abstract

PURPOSE:To obtain an electrostatic charge generating material high in sensitivity characteristics and superior in durability by coupling a diazo component with a mixture of couplers obtained by adding at least one different kind of coupler to a main coupler in an amt. of 10-50mol% of the total couplers. CONSTITUTION:A photoconductive azo pigment is prepared by coupling an azo component with a mixture of couplers obtained by adding at least one different kind of coupler to a main coupler in an amt. of 10-50mol% of the total couplers. Said photoconductive azo pigment is dispersed into a solvent, ana a conductive substrate is directly coated with said dispersion or an adhesive layer formed on the substrate is coated with it to form the charge generating layer, and further a charge transfer layer is laminated on it to obtain a charge generating material. Said azo component is exemplified by ones prepared by tetrazotizing or hexaazotizing diamine or triamine.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an organic photoconductor, and more particularly to a method for producing a particulate azo pigment suitable as a charge-generating material and a charge-generating material.

BACKGROUND ART Conventionally, as electrophotographic photoreceptors made of inorganic photoconductive materials, those using selenium, cadmium sulfide, zinc oxide, etc. have been widely used.

On the other hand, electrophotographic photoreceptors made of organic photoconductive materials include photoconductive polymers typified by poly(N-vinyl λ mesol) and 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole. Those using low-molecular organic photoconductive substances, such as those using low-molecular organic photoconductive substances, and those in which such organic photoconductive substances are combined with various dyes and pigments are known.

Electrophotographic photoreceptors using organic photoconductive substances have the advantage of having good film-forming properties, being able to be produced by coating, having extremely high productivity, and being able to provide inexpensive photoreceptors. 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, a functionally separated photoreceptor has been developed, in which an organic photoconductive pigment is used as a charge generation layer, and a new charge transport layer made of the aforementioned photoconductive polymer or low-molecular organic photoconductive substance is laminated. The sensitivity and durability, which were considered to be disadvantages of conventional organic electrophotographic photoreceptors, have been significantly improved, and they have come to be put into practical use. Furthermore, various compounds and pigments that are suitable for functionally separated photoreceptors have also been discovered.

Among the above charge-generating materials, azo pigments have advantages such as being easy to manufacture and having many variations in structure.In recent years, many materials have been proposed, but when using them, it is necessary to To prevent the diameter from becoming too small,
Using this method, the photoreceptor had disadvantages such as the inability to obtain sufficient force sensitivity, poor potential stability during long-term use, and unevenness of images due to coating film defects.

Problems to be Solved by the Invention The first purpose of the present invention is to improve the dispersibility of pigments, and the second purpose is to improve the dispersibility of pigments. An object of the present invention is to provide a charge generating material for an electrophotographic photoreceptor having potential stability. A third object of the present invention is to select a charge generating material in order to provide an electrophotographic photoreceptor without defects in the coating film by improving pigment dispersibility.

As a result of intensive research to achieve this objective, the inventors of the present invention have discovered the following:
During the synthesis reaction of azo pigments, after tetrazotizing or hexazining diamines or triamines, one or more different couplers are added to the main coupler in an amount of 10 to 50% of the total coupler amount.
It has been found that a pigment mixture obtained by a coupling reaction with a mixed coupler containing molti can be easily made into fine particles by a conventional dispersion method, and a pigment having extremely good stability in a dispersion can be obtained. The present invention was achieved by discovering that it is suitable as a charge generating material.

Specifically, the present invention provides a photoconductive azo pigment characterized in that a mixed coupler in which at least 10 to 50 moles of a different type of coupler is added to the main coupler is coupled with a diazo component. It consists of a manufacturing method and a charge generating material which is an organic photoconductor made of the azo pigment.

As the diazo component, diamines or triamines are tetrazotized or hexadized (in this specification, the term "tetrazotized" refers to the case where the molecule contains two amine groups, regardless of whether or not the molecule has an azo group). A component containing three is defined as hexazation).

The particle size of the charge generating material is generally about 1 μm or less, preferably 0.5 μm or less, but according to the method of the present invention, the pigment particles produced are a mixture of two or more pigments, so the pigment particles are not crushed. easily dispersed, approximately 0.2
It has become possible to produce fine particles with a particle size of less than μ or even less than 0.1 μ.

The influence of the dispersed particle size on the electrophotographic properties is remarkable. For example, when using the pigment obtained in Example 1, when the dispersion time is shortened and the dispersed particle size t is sequentially increased, the effect of the dispersed particle size on the electrophotographic properties is It is clearly recognized that the sensitivity decreases and the fluctuation of the bright area potential (VL) becomes thicker before and after durable use.

The sensitivity and potential fluctuation during durable use were measured using the same measurement method as in the example.

It can be seen from the above table that the finer the dispersed particle size, the better the sensitivity and potential fluctuation, and the preferable particle size is 0.20 μm or less.

Furthermore, in terms of images, a photoreceptor prepared by coating a dispersion liquid with an average particle diameter of 0.2 s or less can provide extremely clear images with fewer image defects such as white spots than those with an average particle diameter of 0.2 s or less.

Next, the present invention will be explained in more detail.

Diamines and triamines used in the present invention include: R2o R22 (8) N (@-NH2).

Aromatic or heteroaromatic amines such as

R1 to di1 in formulas (1) to (b) are hydrogen, chlorine, or bromine.

Halogen atoms such as iodine, alkyl groups such as methyl, ethyl, propyl, alkoxy groups such as methoxy, ethoxy, propoxy, phenoxy groups, nitro groups, etc., and X is 10-1-8-1-N- R52 represents an alkyl group.

Further, as the coupler, a coupler having an aromatic OH group such as a hydroxynaphthoic acid amide type coupler, a hydroxynaphthoic acid imide type coupler or an aminonaphthol type coupler is used, and a particularly preferable coupler in terms of electrophotographic properties is Examples include those represented by the following general formula.

In formula (2), Y is fused with a benzene ring to form a naphthalene ring,
Anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran mt-forming residue, 2 is -coN
RuR35 (where Rxa is a hydrogen atom, a group selected from the group consisting of a substituted or unsubstituted alkyl group, a phenyl group and a phenyl group, and R35 is a group consisting of a substituted or unsubstituted alkyl group, a phenyl group and a naphthyl group) represents a group (represents a selected group).

Substituents for R34 and R35 include alkyl groups such as methyl, ethyl, propyl, butyl, halogen atoms, alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, acyl groups such as acetyl and benzoyl, methylthio, ethylthio, etc. Examples thereof include -jv +, luthio group, aryl group such as phenyl, heptaralkyl group such as benzyl and phenethyl, nitro group, cyano group, dialkylamino group such as dimethylamino and diethylamino.

Rs5 in α◆ represents a group selected from the group consisting of substituted or unsubstituted alkyl groups and phenyl groups. Specifically, R35 is an alkyl group such as methyl, ethyl, propyl, butyl, a hydroxyalkyl group such as hydroxymethyl or hydroxyethyl, an alkoxyalkyl group such as methoxymethyl or ethoxyethyl, a cyanoalkyl group,
aminoalkyl group, N-alkylaminoalkyl group, N
, N-dialkylamino group, halogenated alkyl group, aralkyl group such as benzyl and phenethyl, phenyl group and substituted phenyl group (substituents include R34 and Rs5 in 9 general formula (6)), etc. can give.

The amine and coupler used in the present invention are not particularly limited to the exemplified substances.

The pigment is obtained by tetrazotizing or hexazining diamine or triamine (general formula (8), α0) by a conventional method.
Diamines such as are also expressed as tetrazotized.)
Then, after coupling with a mixed coupler in the presence of an alkali, or isolating the diamine or triamine in the form of a tetrazonium salt, a borofluoride salt, a zinc chloride double salt, etc., a suitable solvent, For example, N
It can be easily produced by coupling with a mixed coupler in the presence of an alkali in a solvent such as , N-dimethylformamide, or dimethyl sulfoxide.

In the coupling reaction, one or more types of different couplers can be used, and the amount used is 10 to 50 mol-1, preferably 20 to 50 mol-1 of the total amount of couplers, from the viewpoint of pigment dispersibility. .

The crude pigment thus obtained was filtered, washed with water, and treated with dimethylformamide (DMF) and dimethylacetamide (DMF).
MAC), methanol, ethanol, isopropyl alcohol (Engineering 1) A), methyl ethyl ketone (MKK)
, methyl in butyl ketone (M to K), benzene, xylene, toluene, tetrahydrofuran (TH, F), etc., and after purification and drying. A fine particle dispersion liquid is prepared from the purified and dried pigment by an appropriate dispersion method.

Pigment dispersion solvents include methanol, ethanol, alcoholic solvents such as PA, acetone, MFiK, M
Various solvents such as ketone thread solvents such as K, cyclohexanone, aromatic solvents such as benzene, toluene, xylene, and chlorinzene, and DMF and DMAC can be used.

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 thread resin, polycarbonate resin, acrylic resin, etc. are used.

The charge generation layer can be formed by coating the above-mentioned dispersion directly onto the conductive support or onto the adhesive layer. It can also be formed by coating on the underlying charge transport layer. The thickness of the charge generation layer is 5μ or less, preferably Q
It is desirable to form a thin film layer having a thickness of , 01 to 1 μm. It is necessary that most of the incident light be absorbed by the charge generation layer to generate a large number of charge carriers, and that the generated charge carriers must be injected into the charge transport layer without p deactivation due to recombination or trapping. Therefore, it is preferable to set the film thickness as described above.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer coating method, a blade coating method, a roller coating method, or a curtain coating method. 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 to 200° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field, and transporting these charge carriers to the surface. have. 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 be laminated on the charge generation layer.

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 "electromagnetic waves" mentioned here include gamma rays, X-rays,
Includes a broad definition of "light rays" that includes ultraviolet rays, visible light, near-infrared rays, infrared rays, far-infrared rays, etc. 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 layers trap each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-dolinitro-9-fluorenone. ,
2,4,5.7-tetranitro-9-fluorenone, 2
．． 4.7-) dinitro-9-dicyanomethylenefluorenone, 2.4,5.7-titranitroxanthone, 2
, 4.8-trinidrothioxanthone and other electron-withdrawing substances, and polymerized products of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-)thyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-6-methylidene-10-ethylphenothiazine, N , N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, P-dielylaminobenzaldehyde-N,N-diphenylhydrazone, P
-Diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, P-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1.3.3
-) dimethylindolenine-ω-aldehyde-N,N-
Hydrazones such as diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1-phenyl- 3-(p-diethylaminostyryl)-s-(p-
diethylaminophenyl) pyrazolines (2))-5-(P-diethylaminostyryl)-5-
(P-diethylaquinophenyl)pyrazoline, 1-[pyridyl (2): l -3-(P-diethylaquinophenyl)-5-(P-diethylaminophenyl)pyrazoline, 1-[6-medoxypyridyl (2) ] -3-(
P-diethylakinostyryl)-,5-(P-diethylaminophenyl)pyrazoline, 1-[pyridyl (5))
-3-(P-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-(revidyl(
2))-3-(P-diethylaminostyryl)-5-(
p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)')-3-(P-diethylaminostyryl)24-methyl-5-(I'-diethylaminophenyl)pyrazoline, 1-[pyridyl(2):l −3−(α
-methyl-P-diethylaminostyryl) -5-(P
-'diethylaminophenyl)pyrazoline, 1-7er-3-(P-diethylaminophenyl)-4-methyl-5-(,P-diethylaminophenyl)pyrazoline,
Pyrazolines such as 1-phenyl-3-(α-benzyl-p-diethylaminostyryl)-5-CP-diethylaminophenyl)pyrazoline and spiropyrazoline, 2-
(P-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(P-diethylaminophel)-4-(P-dimethylaminophenyl)-5-(2
-oxazole compounds such as -chlorophenyl)oxazole, thiazole compounds such as 2-(P-diethylaminostyryl)-6-dinithylaminobenzothiazole,
bis(4+:)ethylamino-2-methylphenyl)
- triarylmethane thread compounds such as phenylmethane, 1
, 1-bis(4-N,N-diethylamine-2-methylphenyl)hebutane, 1.1.2.2-tetrakis(4
-N,N-dimethylamine-2-methylphenyl)bolyarylalkane such as ethane, triphenylamine,
Poly-N-vinylcarbazole, polyvinylvinyl/, polyvinylanthracene, polyvinyl acridine, poly-
Examples include 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.

Further, these charge transport materials L can be used alone or in combination of 2 ml or more.

When the charge transport material does not have film-forming properties,
A film can be formed by selecting a binder.

Examples of resins that can be used as binders include acrylic resin polyarylate, polyester, polycarbonate,
Polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone,
Examples include insulating resins such as polyacrylamide, polyamide, and chlorinated rubber, and organic photoconductive polymers such as expanded poly N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 30μ, but the preferred range is 8 to 20μ.
It is. 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. Examples of substrates having a conductive layer include those in which the substrate itself is conductive;
For example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium,
Nickel, indium, gold, platinum, etc. can be used, and in addition, plastics having a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (for example, Polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, conductive particles A substrate impregnated with plastic or paper, 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 subbing layer is casein,
It can be formed from polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, and the like.

The thickness of the subbing layer is 0.1 to 5μ, preferably 0.3 to 3μ.
μ 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, reaching the surface and neutralizing the positive charge, causing a decrease in surface potential and creating an electrostatic contrast between it and the unexposed area. arise.

A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. Either fix this directly or transfer the toner image to paper or plastic film, etc.
You can achieve this by becoming established and established.

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 visually imaged 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, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. , which then reaches the surface and neutralizes the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast 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 azo pigment of the present invention together with a charge transport material in the same layer. In this case, a charge transfer complex compound consisting of poly N-vinyl hasol 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 organic photoconductor obtained in the present invention and the charge transfer complex compound in a polyester solution dissolved in dihydrofuran, and then forming a film thereon.

The organic photoconductor obtained by the present invention can be used not only in electrophotographic machines, but also in color copiers, laser printers, and
It can also be widely used in electrophotographic applications such as RT printers.

Furthermore, the organic photoconductor obtained by the present invention can be used not only in the above-mentioned electrophotographic photoreceptor but also in solar cells and optical sensors.

Example Hereinafter, the present invention will be explained according to examples.

Example 1 and Comparative Example 1 In a 500-beaker, 80 d of water, concentrated hydrochloric acid 1&6-(0,1
9 mol) 453 t (0,029 mol) was added thereto, and the mixture was stirred while cooling in an ice water bath to bring the liquid temperature to 3°C. Next, sodium nitrite 4.2
t(0,061 mol>1) The solution dissolved in water 7- is heated to a temperature of 3
After the dropwise addition was completed over 10 minutes while controlling the temperature within the range of ~10°C, the mixture was stirred for an additional 30 minutes at the same temperature. Carbon was added to the reaction solution and filtered to obtain a tetrazotized solution.

Next, put 700 m of water in a 21 beaker and add 21 ml of caustic soda.
g (α53 mol), 9.8f (0,
049 mol) and lunaphthol as (
3-Hydrocoir-2-naphthoic acid anilide) 3.16t
(o, 012 mol) was added and dissolved.

This mixed coupler solution is cooled to 6℃, and the liquid temperature is 6 to 10℃.
The above-mentioned tetrazotized solution was soaked under stirring for 30 minutes while controlling the temperature, then stirred at room temperature for 2 hours, and then soaked for 1 hour.
I left it for the night. After filtering the reaction solution, it was washed with water to obtain a crude pigment of 18.7
I got f. Next, washing was repeated five times with each 400-ON N-dimethylformamide. After that, each 500-
The purified pigment was washed 3 times with MKK and dried under reduced pressure at 80°C. I got Of.

Next, 4t of this purified pigment was dispersed in a sand mill for 8 hours with a solution containing THFa4y and 2f of butyral resin (degree of butyralization: 63 mol%).

On the other hand, for comparison, a single composition pigment was synthesized and dispersed in the same manner using only 2-hydroxynaphthoic acid methylamide without mixing different couplers, and the dispersibility was compared. The results are shown in FIG.

Here, the average particle diameter was measured using a centrifugal particle size distribution analyzer CAPA-500 manufactured by Horiba, Ltd. The average particle diameter after dispersion was 0.48μ in the case of a single composition pigment, whereas it was 0.15μ in the case of a 7'C pigment material mixed with different couplers. It can be seen that the resulting pigment has extremely excellent dispersibility.

The stability of the dispersion was also good despite the fact that it was in a fine particle state, with an average particle size of 0.17μ after one force.

Next, in order to compare electrophotographic characteristics, photoreceptors were prepared as follows.

Ammonia aqueous solution of casein (casein 1
t2f, 28% ammonia water 19° water 222d) was applied by dipping method so that the film thickness after drying was 1.0 μm, and dried.

Next, the pigment dispersions for Example 1 and Comparative Example 1 were applied by dipping to a film thickness of 0.5μ, respectively.
It was dried to form a charge generation layer.

Then, P-diethyl□aminobenzaldehyde-, N
, N-diphenylhydrazone 51 and polymethyl methacrylate resin (number average molecular weight 10QOOO) were dissolved in 5tf benzene 70-, and this was applied onto the charge generation layer by a dipping method so that the film thickness after drying was 12μ, It was dried to form a charge transport layer.

The electrophotographic photoreceptor thus prepared was statically corona charged at 15 KV using Kawaguchi Denki's Seiden Copying Paper and a testing device "Modetsp-428", and then placed in a dark place for 1.
After being held for a second, it was exposed to light at an illuminance of 5 Lux, and the charging characteristics were examined.

The charging characteristics include the surface potential (Vp) and the exposure amount (I [lA
) was measured. The results are shown in Table 1.
580 4.6 Comparative Example 1 595 B, 3 Furthermore, in order to measure the variation in bright area potential and dark area potential after repeated use, the photoreceptor prepared in this example was exposed to a -5.6 KV" corona. Charger, exposure amount 12twx, AEC exposure optical system,
It was attached to the cylinder of an electrophotographic copying machine equipped with a developer, a transfer charger, 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 (VL) and dark area potential (CVn) are respectively -
The light area potential (vL) and the dark area potential (VD) were measured after being set at around 600V and -100V and used 5000 times.

The results are shown in Table 2.

Table 2 Initial After 5000 cycles vy-ri VL(-v) VD(-ri Wb(-
Example 1 575 100 580 110 Comparative Example i 585 105 615 185 According to the results in Tables 1 and 2, the photoreceptor using the organic photoconductor obtained in the present invention has a high sensitivity and V' during long-term use. It can be seen that the stability of D and VI is also extremely superior to that of the conventional method.

Further, the obtained grating image was an image with many white spots in the case of the photoreceptor of Comparative Example 1, whereas a good image with few defects was obtained with the photoreceptor of Example 1.

Example 2 and Comparative Example 2 In a 500-meter beaker, 80 ml of water and 212 ml of concentrated hydrochloric acid, amine (IQ), (1 (α0 40 mol)) were added, and the mixture was stirred slowly in an ice-water bath to bring the liquid temperature to 2°C. Nitrite 7-f 5.
A solution of 8t (a, 084 mol) dissolved in 1 od of water was heated for 25 minutes while controlling the temperature of solution m within the range of 2 to 7℃.
After the addition was completed, the mixture was further stirred at the same temperature for 30 minutes. The reaction solution was carbon-filtered to obtain a tetrazotized solution.

Next, put 10o (1wt) of water into a 2L beaker and dissolve 29.2f (173 mol) of caustic soda.
α9Of (0,0042 mol) and t322 (α0042
mol) and α96t (00042 mol) were added and dissolved.

Dissimilar coupler 1 2
3 Next, this mixed coupler solution was cooled to 6°C, and while controlling the liquid temperature at 6 to 10°C, the above-mentioned Tetop forming solution was added dropwise with stirring over 30 minutes, then stirred at room temperature for 2 hours, and then left overnight. did. The reaction solution was filtered and washed with water to obtain crude pigment 29.6F.

Next, washing was repeated 5 times with each 500-ON and N-dimethylformamide, and further washed 3 times with each 500-ON MEK, and dried under reduced pressure at 80°C to obtain purified pigment 26.9f.

Next, 4 tons of this purified pigment was dispersed in a sand mill for 10 hours with a solution containing 84 tons of 1,4-dioxane and 2F butyral resin (butyralization degree: 63 moles). On the other hand, for comparison, the pigment of a single composition synthesized without mixing different couplers was similarly dispersed and the dispersibility was compared. The results are shown in FIG.

It can be seen from FIG. 2 that the pigment obtained according to the present invention has extremely excellent dispersibility. The stability of the dispersion was also good despite the fact that it was in a fine particle state, and the average particle size after one month was Q, 12μ.

Next, in order to compare the electrophotographic characteristics, photoreceptors were prepared in exactly the same manner as in Example 1, and the charging characteristics and the potential characteristics during durable use were compared using the same evaluation method. The results are shown in Tables 3 and 4.

Table 3 VD (-v) KM (Auc, aec) Example 2
590 5.1 Comparative Example 2 585
7.8 Table 4 Initial After 5000 cycles Vp (-v) Vp (-v) VD (-v)
V: t, (-v) Example 2 580 95 15
110 Comparative Example 2 590 100 630 18
According to the results in Tables 3 and 4, the photoreceptor using the organic photoconductor obtained in the present invention, as in Example 1, is superior to the conventional ones in terms of sensitivity and stability of VD and VI during long-term use. It can be seen that it is extremely superior to the legal one.

Example 3 In conjunction with Example 1, the heteropolar coupler naphthol A
The dispersibility and electrophotographic properties of the resulting pigments were investigated when the amount of s added was varied.

The results are shown in Table 5.

The same dispersion treatment, photoreceptor preparation, and electrophotographic property evaluation method were performed in exactly the same manner as in Example 1.

According to the results in Table 5, when the amount of the different coupler added is less than 5, the dispersibility is poor and the electrophotographic properties are also poor.
! It can be seen that when j is exceeded, the dispersibility becomes extremely good, and the electrophotographic properties also become extremely good. In terms of images, when the amount added is less than 5 mol (average particle size 0.35μ or more), many image defects such as white spots are observed.
When the amount added is 10 to 50 moles or more, good images with extremely few image defects can be obtained.

Effects of the Invention As described above, according to the present invention, a photoconductive composition (photoconductive azo pigment) with good dispersibility can be obtained, which is excellent as a charge-generating material. I can give it to you.

[Brief explanation of drawings]

FIG. 1 is a graph comparing the dispersibility of pigments according to Example 1 and Comparative Example 1, and FIG. 2 is a graph comparing dispersibility of pigments according to Example 2fiP and Comparative Example 2. Figure 1 Dispersion between trout with evening patterns

Claims (3)

[Claims] (1) A method for producing a photoconductive azo pigment, which comprises coupling a mixed coupler in which a main coupler contains one or more different couplers in an amount of 10 to 50 mol % based on the total amount of couplers, with a diazo component. (2) An organic photoconductor consisting of a photoconductive azo pigment obtained by coupling a mixed coupler in which one or more different couplers are added in 10 to 50 mol% of the total coupler amount to the main coupler with a diazo component. Certain charge-generating materials. (3) The charge generating material according to claim 2, wherein the organic photoconductor made of a photoconductive azo pigment has an average particle size of 0.2 μm or less.