JP2002091038A - Electrophotographic photoreceptor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent electrophotographic characteristics, particularly a holding rate by using a charge generating material having an excellent potential holding rate, and to provide a method for manufacturing the photoreceptor by using a coating liquid. SOLUTION: In the electrophotographic photoreceptor having a photosensitive layer on a conductive substrate and containing a pohthalocyanine compound as a photoconductive material in the photosensitive layer, the phthalocyanine compound is prepared by synthesizing from the starting material containing orthophthalodinitrile and controlling the temperature increasing rate for the synthesis to <=2.0 deg.C/minute in the reaction temperature range from -10 to +20 deg.C of the melting point 141 deg.C of the orthophthalodinitrile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor (hereinafter, also simply referred to as "photoreceptor") used for an electrophotographic printer, copier, facsimile, and the like. The present invention relates to an electrophotographic photoreceptor having an excellent retention by improving a method for synthesizing a charge generation material as a conductive material, and a method for producing the same.

[0002]

2. Description of the Related Art Photoreceptors for electrophotography generally have a function of retaining surface charges in a dark place, a function of receiving light to generate charges, and a function of transporting charges generated by receiving light. So-called single-layer type photoreceptor that combines these functions in one layer, a layer that mainly contributes to charge generation, and a layer that contributes to surface charge retention in dark places and charge transport during photoreception And a laminated type photoreceptor in which layers having different functions are laminated.

For example, the Carlson method is applied to image formation by electrophotography using these electrophotographic photosensitive members. Image formation in this method involves charging a photoconductor by corona discharge in a dark place, forming an electrostatic latent image such as a character or a picture of a document on the charged photoconductor surface, and forming the formed static image. The development is performed by developing the electrostatic latent image with toner and transferring and fixing the developed toner image to a support such as paper. After the transfer of the toner image, the photoconductor is subjected to static elimination, removal of residual toner, light neutralization, and the like. Later, it is used again.

Conventionally, as the photosensitive material of the above-described electrophotographic photosensitive member, in addition to a material in which an inorganic photoconductive substance such as selenium, a selenium alloy, zinc oxide or cadmium sulfide is dispersed in a resin binder, An organic photoconductive substance such as poly-N-vinylcarbazole, polyvinylanthracene, a phthalocyanine compound or a bisazo compound is dispersed in a resin binder, or a material obtained by vacuum evaporation is used.

In an electrophotographic application apparatus using such an electrophotographic photosensitive member, digital recording apparatuses such as a laser printer, a laser facsimile, and a digital copying machine have been widely put into practical use with the development of digitization technology in recent years. ing. Many of these devices employ a latent image forming method of irradiating a photoconductor with a semiconductor laser beam. Therefore, in order to reduce the size and cost of the device, a light source having an oscillation wavelength in a long wavelength region of 750 nm or more is used. The photoreceptor used is required to have high sensitivity in a long wavelength region of 750 to 850 nm. Due to the requirement of such photosensitivity characteristics, in recent years, as a photoconductive material, an organic photoconductive substance such as a phthalocyanine compound or a bisazo compound as described above has been used instead of an inorganic pigment which has been widely used in the past. Are increasing.

In particular, phthalocyanine compounds have high sensitivity characteristics up to a relatively long wavelength region and exhibit various photoconductive characteristics depending on the type of central metal and crystal form thereof. Many are adopted. For example, as divalent phthalocyanine,
ε-type copper phthalocyanine, γ-type metal-free phthalocyanine, etc.
Examples of the trivalent or tetravalent metal phthalocyanine include chloroaluminum phthalocyanine, chloroaluminum phthalocyanine chloride, titanyloxyphthalocyanine, chloroindium phthalocyanine, and the like.
Various phthalocyanines containing titanium, tin, lead and the like as group metals are mentioned. In addition, these phthalocyanines are subjected to solvent or solvent vapor treatment, or are subjected to sublimation treatment to increase the sensitivity, introduce various substituents and derivatize, and further perform dimerization or trimerization to achieve longer wavelength and higher wavelength. Methods for increasing sensitivity have been reported.

[0007]

As described above, the use of phthalocyanine compounds as a photosensitive material for an electrophotographic photoreceptor is known, and its purification has been variously studied. It has not always been clear how synthesis conditions and the amount of by-produced impurities in the production process of the phthalocyanine compound affect the performance of the photosensitive material and, consequently, the characteristics of the photoreceptor.

Accordingly, an object of the present invention is to clarify such a relationship and to use a charge generating material having an excellent potential holding ratio to provide an electrophotographic photosensitive member having excellent electrophotographic characteristics, particularly, an excellent holding ratio. And a method for producing the same using a coating liquid.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, as a phthalocyanine compound as a photoconductive material used in a photosensitive layer of a photoreceptor,
By using orthophthalonitrile as one of the starting materials and using a phthalocyanine compound synthesized under specific heating conditions, it is possible to obtain a photoreceptor having excellent electrophotographic characteristics, particularly excellent potential holding ratio. And completed the present invention.

That is, in order to solve the above problems, the electrophotographic photoreceptor of the present invention has a photosensitive layer on a conductive substrate,
In the electrophotographic photoreceptor in which the photosensitive layer contains at least a phthalocyanine compound as a photoconductive material, the phthalocyanine compound contains orthophthalodinitrile as a starting material, and at least the melting point of the orthophthalodinitrile is -10 to + 20 ° C. , In particular, a reaction temperature of 131 to 161 ° C, in particular a temperature range of -20 to + 30 ° C.
It is characterized by being synthesized at a synthetic temperature rising rate of 2.0 ° C./min or less at 1 to 171 ° C.

Further, the method of manufacturing an electrophotographic photoreceptor of the present invention includes the step of forming a photosensitive layer by applying a coating solution containing a charge generating material as a photoconductive material on a conductive substrate. In the method for producing a photoreceptor for use in the present invention, as the charge generation material, orthophthalonitrile is used as a starting material and at least the melting point 141 of the orthophthalonitrile is used.
A phthalocyanine compound synthesized using a synthesis temperature increasing rate of 2.0 ° C./min or less in a reaction temperature range of −10 ° C. to + 20 ° C. is used.

[0012]

Embodiments of the present invention will be described below in detail. The electrophotographic photoreceptor includes a so-called negatively charged laminated photoreceptor, a positively charged laminated photoreceptor, and a positively charged single-layer photoreceptor. It includes both a single-layer type and a laminated type, and is not limited to either. Hereinafter, the present invention will be specifically described by taking the negatively charged laminated photoreceptor shown in FIG. 1 as an example, but components, methods, and the like for formation or production of the photoreceptor other than phthalocyanine compounds are appropriately It is possible to select a suitable one.

In the negatively charged laminated photoreceptor shown in FIG. 1, a photosensitive layer 3 is laminated on an undercoat layer 2 formed on a conductive substrate 1, and the photosensitive layer 3 is composed of a charge generation layer 4
It is of a function-separated type formed by laminating a layer having a function separation on the charge transfer layer 5 and the charge transport layer 5. Although not shown, the photosensitive layer 3
It is also possible to further provide a surface protective layer thereon.

The conductive substrate 1 functions not only as an electrode of the photoreceptor but also as a support for the other layers, and may be cylindrical, plate-like or film-like. Alternatively, a conductive material may be applied to a metal such as stainless steel or nickel, or glass or resin.

The undercoat layer 2 is composed of the conductive substrate 1 and the photosensitive layer 3
It can be provided for the purpose of preventing injection of unnecessary charges into the substrate, covering defects on the surface of the substrate, improving the adhesiveness of the photosensitive layer, and the like. The photoreceptor of the present invention is not necessarily required for any of the above types. As a material of the undercoat layer 2, for example, an alcohol-soluble polyamide, a solvent-soluble aromatic polyamide, a thermosetting urethane resin, or the like can be used. As the alcohol-soluble polyamide, nylon 6,
Nylon 8, Nylon 12, Nylon 66, Nylon 6
And N-alkyl-modified or N-alkoxyalkyl-modified nylon, and the like. Specific examples of these compounds include Amiran CM8000 (manufactured by Toray Industries, Inc., 6/66/610 /
12 copolymer nylon), Elbamide 9061 (manufactured by Dupont Japan Co., Ltd., 6/66/612 copolymer nylon), DAIAMID T-170 (manufactured by Daicel-Huls Co., Ltd., nylon 12-based copolymer nylon) and the like. Can be.

In the undercoat layer 2, TiO ₂ , Sn
Inorganic fine powders such as O ₂ , alumina, calcium carbonate, and silica can be used.

The charge generation layer 4 is formed by vacuum-depositing an organic photoconductive material or applying a material in which particles of the organic photoconductive material are dispersed in a resin binder, and receiving light to form a charge. Occurs. It is important for the charge generation layer 4 to have high charge generation efficiency and at the same time to inject the generated charge into the charge transport layer, and it is preferable that the charge generation layer 4 has little electric field dependence and good injection even at a low electric field.

In the present invention, ortho-phthalodinitrile is used as a starting material as a charge-generating substance as a photoconductive material used in the charge-generating layer 4, and the melting point of ortho-phthalodinitrile is -10 to + 20.degree. Especially -2
It is important to use a phthalocyanine compound synthesized at a synthesis temperature rising rate of 2.0 ° C./min or less in a reaction temperature range of 0 to + 30 ° C. The mechanism by which the potential holding ratio of the photoreceptor increases in this manner is not necessarily clear, but can be considered as follows.

That is, in the synthesis of phthalocyanine in which the reaction proceeds by heating, the starting material orthophthalonitrile has a melting point of 141 ° C. of −10 ° C. to + 20 ° C., especially −20 ° C.
In the temperature range of up to + 30 ° C., that is, 131 to 161 ° C., particularly 121 to 171 ° C., a further increase in temperature in the system occurs due to heat generation due to rapid progress of the phthalocyanine production reaction. Therefore, an abnormal reaction of phthalonitrile can be prevented by setting the rate of temperature rise in the synthesis in this temperature range to 2.0 ° C./min or less. It is also useful to temporarily maintain the temperature within a temperature range around the melting point of 141 ° C. of the phthalodinitrile.
If the temperature is rapidly increased within this range, a phthalonitrile multimer as a by-product or an abnormal reaction occurs, and the resulting performance of the phthalocyanine compound as a charge generating material and, consequently, the photoreceptor characteristics are deteriorated.

Examples of the phthalocyanine compound include titanyl oxo phthalocyanine, metal-free phthalocyanine,
Or, the central element is a transition metal selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium, molybdenum, rhodium, cerium, neodymium, samarium, europium and tungsten, or indium, Gallium, aluminum, germanium, tin, antimony,
A phthalocyanine compound which is an element selected from the group consisting of lead, bismuth, silicon and phosphorus is preferred. Also,
The following general formula (1), (Where M is titanium, vanadium, chromium, manganese,
Iron, cobalt, nickel, zirconium, niobium, molybdenum, rhodium, cerium, neodymium, samarium,
Europium, tungsten, indium, gallium,
Aluminum, germanium, tin, antimony, lead,
Bismuth, silicon or phosphorus or oxides thereof,
Represents a hydroxide or a halide, and R ^{1 to} R ¹⁶ are
Each independently a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an ester group, an alkyl group, an aryl group,
(Representing an alkenyl group, an alkoxyl group or a phenoxyl group) can also be suitably used.

The method for producing a phthalocyanine compound from orthophthalodinitrile according to the present invention is known and described, for example, in PHTHALOCYANINES CCLeznoff et al., 1989 (VCH P
ublishers.Inc,) or THE PHTHALOCYANINES FHMo
Ser. et al., 1983 (CRC Press), etc., can be used for production, but none of the references disclose the setting of heating conditions in a specific temperature range according to the present invention.

In the present invention, as the charge generating substance,
It is necessary that at least the phthalocyanine compound according to the present invention described above is contained, but other charge generating substances, for example, various azo, quinone, indigo, cyanine, squarylium, azurenium compounds and the like may be used in combination. It is possible.

Examples of the resin binder for the charge generation layer 4 include polycarbonate, polyester, polyamide, polyurethane, epoxy, polyvinyl butyral, phenoxy,
Polymers and copolymers of silicone and methacrylic acid esters, and halides and cyanoethyl compounds thereof can be used in appropriate combinations.
The amount of the charge generating material used is determined by the amount of the resin binder 100
The amount is usually 10 to 5000 parts by weight, preferably 50 to 1000 parts by weight based on parts by weight.

Since the charge transport layer 5 is laminated on the charge generation layer 4, its thickness is determined by the light absorption coefficient of the charge generation material, and is generally 5 μm or less, preferably 1 μm.
It is as follows. In addition, the charge generation layer 4 can be used with a charge generation substance as a main component and a charge transport substance added thereto.

The charge transport layer 5 comprises a resin binder containing a charge transport material, for example, various hydrazone compounds, styryl compounds, amine compounds, and derivatives thereof.
A coating film made of a material dispersed alone or in an appropriate combination, and has a function of retaining charges of the photoreceptor as an insulator layer in a dark place and transporting charges injected from the charge generation layer 4 when receiving light. . As the resin binder for the charge transport layer 5, polycarbonate, polyester, polystyrene, polymers of methacrylic acid esters, mixed polymers, copolymers, and the like are used, but mechanical, chemical and electrical stability, The compatibility with the charge transport material used other than the adhesion is important. The amount of the charge transporting substance to be used is generally 20 to 500 parts by weight, preferably 30 to 300 parts by weight, based on 100 parts by weight of the resin binder. The thickness of the charge transport layer 5 is preferably in the range of 3 to 50 μm, more preferably 15 to 50 μm, in order to maintain a practically effective surface potential.
40 μm.

The method for producing a photoreceptor of the present invention comprises a step of forming a photosensitive layer by applying a coating solution containing a charge generating material as a photoconductive material on a conductive substrate.
As the charge generating material to be used, any material may be used as long as the phthalocyanine compound according to the present invention described above is used.

Further, the coating liquid in the production method of the present invention can be applied to various coating methods such as a dip coating method or a spray coating method, and is not limited to any one of the coating methods.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples. <Example 1> A polyamide resin (Amilan CM800 manufactured by Toray Industries, Inc.) for forming an undercoat layer
0) 70 parts by weight and methanol (Wako Pure Chemical Industries, Ltd.)
930 parts by weight) was prepared to prepare an undercoat layer coating solution. Next, this undercoat layer coating solution was applied onto an aluminum substrate as a conductive substrate by a dip coating method, to form a 0.5 μm-thick undercoat layer after drying.

Formation of Charge Generating Layer First, a phthalocyanine compound as a charge generating material was produced according to the following procedure. In a reaction vessel, 800 g of orthophthalodinitrile (mp (melting point) = 141 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) and quinoline (Kanto Chemical Co., Ltd.)
1.8 liters) and stirred. Then, under a nitrogen atmosphere, titanium tetrachloride (manufactured by Kishida Chemical Co., Ltd.) 297
g was added dropwise and stirred. After the dropwise addition, the reaction vessel was heated to raise the temperature inside the system, and the temperature was raised by adjusting the rate of temperature rise from 121 to 171 ° C to 0.5 ° C / min. afterwards,
Raise the temperature to 180 ° C, and at 180 ° C for 15 hours,
The mixture was reacted by heating and stirring.

The reaction mixture was allowed to cool to 130 ° C., and then filtered. N-methyl-2-pyrrolidinone (Kanto Chemical Co., Ltd.)
Was washed with 3 liters. This wet cake,
Under nitrogen atmosphere, the mixture was heated and stirred at 1.8 ° C. for 1 hour with 1.8 liters of N-methyl-2-pyrrolidinone. This was filtered and 3 liters of N-methyl-2-pyrrolidinone,
Washing was performed sequentially with 2 liters of acetone (manufactured by Kanto Chemical Co., Ltd.), 2 liters of methanol (manufactured by Kanto Chemical Co., Ltd.), and 4 liters of hot water.

The thus obtained titanyl oxo phthalocyanine wet cake was further heated at 80 ° C. for 1 hour in diluted hydrochloric acid obtained by adding 360 ml of 36% hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) to 4 liters of water. Stirred. This was allowed to cool, filtered, washed with 10 liters of warm water, and dried.

96% sulfuric acid below -5 ° C (Kanto Chemical Co., Ltd.)
200 g of the above dried product was added to 4 kg while cooling and stirring so that the liquid temperature did not exceed -5 ° C. Then-
It was kept at 5 ° C., cooled for 1 hour and stirred. Cool to 35 liters of water and 5 kg of ice so that the liquid temperature does not exceed 10 ° C.
The above-mentioned sulfuric acid solution was added with stirring, cooled for 1 hour, and stirred. This was filtered and washed with 10 liters of warm water.

This was further heated and stirred at 80 ° C. for 1 hour in dilute hydrochloric acid obtained by adding 770 ml of 36% hydrochloric acid to 10 liters of water. This was allowed to cool, filtered, washed with 10 liters of warm water, and dried.

This was combined with 0.5 liter of water and 1.5 liter of o-dichlorobenzene (Kanto Chemical Co., Ltd.)
It was placed in a ball mill containing 6.6 kg of zirconia balls having a diameter of 8 mm and milled for 24 hours. This was taken out with 1.5 l of acetone and 1.5 l of methanol, filtered, washed with 1.5 l of water and dried.

10 parts by weight of the titanyl oxophthalocyanine thus obtained, 10 parts by weight of a vinyl chloride resin (MR-110, manufactured by Zeon Corporation), 686 parts by weight of dichloromethane and 294 parts by weight of 1,2-dichloroethane Were mixed and ultrasonically dispersed to prepare a charge generation layer coating solution. This charge generation layer coating solution was applied onto the undercoat layer by dip coating to form a 0.2 μm-thick dried charge generation layer.

Formation of charge transport layer 4- (diphenylamino) benzaldehyde phenyl (2-thienylmethyl) hydrazone (Fuji Electric Co., Ltd.)
100 parts by weight), 100 parts by weight of polycarbonate resin (manufactured by Teijin Chemicals Ltd., Panlite K-1300), 800 parts by weight of dichloromethane, 1 part by weight of silane coupling agent (KP-340, manufactured by Shin-Etsu Chemical Co., Ltd.) Was mixed with 4 parts by weight of bis (2,4-di-tert-butylphenyl) phenylphosphonite (manufactured by Wako Pure Chemical Industries, Ltd.) to prepare a charge transport layer coating solution. This charge transport layer coating solution is applied on the charge generation layer by a dip coating method,
A charge transporting layer having a thickness of 20 μm after drying was formed to produce a photoconductor for electrophotography.

Example 2 A photoreceptor was manufactured in the same manner as in Example 1 except that the rate of temperature rise at a reaction temperature of 121 to 171 ° C. during the synthesis of titanyloxophthalocyanine was 1.0 ° C./min.

Example 3 A photoreceptor was produced in the same manner as in Example 1 except that the rate of temperature rise at a reaction temperature of 121 to 171 ° C. during synthesis of titanyloxyphthalocyanine was 2.0 ° C./min.

Example 4 The temperature was raised at a reaction temperature of 121 to 160 ° C. at a reaction temperature of 121 ° C./160° C./min during the synthesis of titanyloxyphthalocyanine, and the temperature was raised at 160 ° C. for 1 hour. A photoreceptor was manufactured in the same manner as in Example 1, except that the temperature was raised at a rate of 1.0 ° C./min.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that the rate of temperature rise at the reaction temperature of 121 to 171 ° C. during the synthesis of titanyloxyphthalocyanine was 3.0 ° C./min.

Comparative Example 2 A photoreceptor was produced in the same manner as in Example 1, except that the rate of temperature rise at the reaction temperature of 121 to 171 ° C. during synthesis of titanyloxyphthalocyanine was 5.0 ° C./min.

The electrical characteristics of the photoreceptors obtained in the above Examples and Comparative Examples were measured using an electrostatic recording paper tester (EPA-8200, manufactured by Kawaguchi Electric Works). The photoreceptor was charged to a surface potential of −600 V by a corotron in a dark place, allowed to stand in a dark portion for 5 seconds, and the potential holding ratio (%) during that time was measured. The results obtained are shown in Table 1 below.

[0043]

[Table 1]

As is clear from Table 1, the photoreceptors of the examples all have high retention rates and are good, while the photoreceptors of the comparative examples have low retention rates as compared with the examples. .

[0045]

As described above, according to the present invention, a phthalocyanine compound as a photoconductive material used for a photosensitive layer is synthesized under a specific temperature-raising condition. It has become possible to provide a photoreceptor having excellent characteristics, especially excellent potential holding ratio.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one configuration example of an electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 undercoat layer 3 photosensitive layer 4 charge generation layer 5 charge transport layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Kino 4-181-1, Chikuma, Matsumoto-shi, Nagano Fuji Electric Imaging Devices Co., Ltd. (72) Inventor Teruo Sasaki 1 Tanabe Shinden, Kawasaki-ku, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. (72) Inventor Kenichi Hara 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in Fuji Electric Co., Ltd. (Reference) 2H068 AA19 BA38 BA39 EA04 EA12

Claims (8)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, the photosensitive layer containing at least a phthalocyanine compound as a photoconductive material, wherein the phthalocyanine compound is orthophthalodinitrile as a starting material. Characterized in that at least the orthophthalodinitrile is synthesized at a synthesis temperature rising rate of 2.0 ° C./min or less in a reaction temperature range of −10 ° C. to + 20 ° C. with a melting point of 141 ° C. body. 2. The electrophotographic photoconductor according to claim 1, wherein the reaction temperature range is −20 to + 30 ° C., which is a melting point of 141 ° C. of the orthophthalonitrile. 3. The electrophotographic photoconductor according to claim 1, wherein the phthalocyanine compound is titanyloxophthalocyanine. 4. The electrophotographic photoconductor according to claim 1, wherein the phthalocyanine compound is a metal-free phthalocyanine. 5. The method according to claim 1, wherein the central element of the phthalocyanine compound is titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium, molybdenum,
3. The electrophotographic photoconductor according to claim 1, wherein the photoconductor is a transition metal selected from the group consisting of rhodium, cerium, neodymium, samarium, europium and tungsten. 6. The electrophotographic photoconductor according to claim 1, wherein the central element of the phthalocyanine compound is selected from the group consisting of indium, gallium, aluminum, germanium, tin, antimony, lead, bismuth, silicon and phosphorus. . 7. The phthalocyanine compound represented by the following general formula (1): (Where M is titanium, vanadium, chromium, manganese,
Iron, cobalt, nickel, zirconium, niobium, molybdenum, rhodium, cerium, neodymium, samarium,
Europium, tungsten, indium, gallium,
Aluminum, germanium, tin, antimony, lead,
Bismuth, silicon or phosphorus or oxides thereof,
Represents a hydroxide or a halide, and R ^{1 to} R ¹⁶ are
Each independently a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an ester group, an alkyl group, an aryl group,
An electrophotographic photoconductor according to claim 1 or 2, wherein the alkenyl group, the alkoxyl group or the phenoxyl group is represented. 8. A method for producing a photoconductor for electrophotography, comprising a step of applying a coating solution containing a charge generation material as a photoconductive material on a conductive substrate to form a photosensitive layer, wherein the charge generation material is A phthalocyanine compound which is synthesized using orthophthalodinitrile as a starting material and at least a synthesis rate of 2.0 ° C / min or less in a reaction temperature range of -10 ° C to + 20 ° C with a melting point of 141 ° C of the orthophthalonitrile. A method for producing an electrophotographic photoreceptor, comprising: